RIVETING LIGHT ALLOY STRUCTURES
Document Type:
Collection:
Document Number (FOIA) /ESDN (CREST):
CIA-RDP81-01043R001900110002-3
Release Decision:
RIPPUB
Original Classification:
K
Document Page Count:
441
Document Creation Date:
December 23, 2016
Document Release Date:
April 12, 2013
Sequence Number:
2
Case Number:
Publication Date:
January 1, 1954
Content Type:
REPORT
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Attachment | Size |
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CIA-RDP81-01043R001900110002-3.pdf | 27.88 MB |
Body:
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41 AIR TECHNICAL INTELLIGENCE
TRANSLATION
(Title Unclassified)
RIVETING LIGHT ALLOY STRUCTURES
(Klepka Konstruktsiy Iz Legkikh Splavov)
Source: State Publishing House For The
Defense Industry
Moscow
1954
348 Pages
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V.P.Grigorlyev
and
P.B.Goldovskiy
RIVETING LIGHT ALLOY
STRUCTURES
State Publishing House
for the
Defense Industry
Moscow, 1954
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This book describes the technological processes of riveting metal structures
made from light alloys. The methods and means of mechanization and automation of
these processes are investigated, and data are given on rivets and on the tools used
in riveting.
The content of this book deals chiefly with the basic processes of assembling
and riveting, as applied to the particular requirement of naking hermetically tight
joints, and also with the methods and procedures used in testing as well as with the
selection of auxiliary equipment and instruments.
The book is intended for technical personnel, foremen, maintenance supervisors
LINN
in plants, and may also be used as a manual by students in institutions of higher
learning.
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PREFACE
In the manufacture of various structures from light metal alloys, the basic re-
quirement is that the riveted joints must be inseparable. The wide use of riveting
was adopted particularly in the construction of aircraft. The increase in the speed
of airplanes, the necessity of producing hermetically tight riveted joints and sur-
faces, the required accurate surface finish of the exterior surfaces of the assem-
bled units, all stepped up the requirements made on riveted joints.
The higher quality requirement of riveted joints, and the large extent to which
riveting work is done, necessitates measures to maintain quality and reduce labor
costs. In taking such measures, first consideration should be given to the training
and improvement of the qualifications of the technical personnel, such as foremen,
maintenance supervisors, and riveters; the use of well-built auxiliary equipment,
instruments and tools; the utilization of correct technological processes of assem-
bly'and riveting; a trained labor organization and a good place in which the work is
done.
This book contains data on assembly accessories, riveting tools, rivets, as
well as a study on the construction and methods of utilizing to advantage, riveting
,presses, drilling machines, auxiliary appliances, etc. An important portion of this
'book consists of a description of the technical processes of assembly of riveted
1
- work, both in joining separate parts and in assembling complete units. Data are
given on each of the technical processes, on the equipment and tools used, on the
-
organization of the labor crew, and on the location in the plant where the work is
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done.
The technical processes described in connection with the assembly of riveted
parts are illustrated with graphs, pointing out the' advantages and the deficiencies
of the processes applied; in particular, it is shown that press riveting is super-
ior to percussion riveting, and drilling is better than punching of holes. Compara-
tive data are given on the strength of joints made with different types of rivets,
on the strength of riveted and welded joints, and also on the technical and economic
aspects of standard types of nonseparable joints.
This book is primarily intended for technologists, foremen, maintenance super-
visors, and inspectors in industrial plants. It may also be used as a textbook by
students in the intermediate and in higher technical institutions of learning.
Chapters I, II, III, VII, XI, XII, XIII, and XVII were written by Candidate of
Technical Sciences B.P.Grigorlyev. Chapters IV, V, VI, IX, X, XIV, XV, and XVI were
written by Engineer P.B.Goldovskiy.
The data given in this book are based on the experience and work done by the
authors on the subjects treated, on the prevailing practice in industrial plants,
and on the work done by the Scientific Research Institute. The description of some
of the riveting presses was supplied by the Laboratory Institute. In the preparation
of this book for publication, the descriptions were ma:dein the form presented by a
group of machinery designers, under the leadership of the well-known designer
'V.G.GOrokhov.
The authors wish to express their deep gratitude to Lecturer S.A.Vigdorchik,
who has made many valuable suggestions in reviewing the manuscript of the book, and
to Engineer V.I.Tikhonov for the assistance rendered by him in-editing the book.
iii
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PART I
GEKERAL CONSIDERATIONS ON THE_ ASSEMBLY
OF RIVETED JOINTS
CHAPTER I
PURPOSE AND METHODS OF ASSEMBLY '
In the production of structures from light metal alloys, the assembly of parts
by riveting represents a considerable proportion of the work. For example, in the
manufacture of modern all?metal aircraft, riveting constitutes from 30 to 35% of the
labor involved in the production of the craft. The amount of labor involved in the
assembly of parts by riveting depends on the availability of proper equipment and on
the technical aspects of supervision and the preliminary preparation of the parts.
One of the essential factors in connection with the design and construction of
riveted parts is their classification as major assembled units, and of these units
into tie components, panels, and sections. The advantage of making this classifica?
tion is that it permits using highly mechanized equipment for drilling, counter?
sinking, and riveting, thus simplifying the work of assembly. All this results in a
reduction of labor, less time of assembly and, consequently, in lower cost of pro?
duction.
In Figs .1 and 2 are shown a wing and a fuselage, dismantled into their con?
stituent components as ties or connecting parts, panels, and sections.
Depending on the nature of the parts from which the product is made, we may
divide them into two basic classes of riveted work (Table 1): namely, 1) frames or
tie parts and panels, and 2) assembled units.
The assembly of minor components and of panels represents a comparatively small
amount of assembly work and does not require complicated equipment, It permits the.
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Fig.1 ? Examples of Wing Elements
1, 21 3) Longerons; 4) Wing rib; 5) Top panel; 6) Bottom panel; 7) Tail
section; 8) Flap; 9) Tail fairing; 1&) Aileron; 11) Wing in assembled view
'2
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3
5
10
11
12
/3
$44,d
Fig.2 - Examples of the Members of a Fuselage
;1) Panel lining of the tail section of the fuselage; 2) Frame ribs of the tail sec-
tion; 3) Tail faring; 4) False rib; 5) Tail section in assembled view; 6) Framework
carcass underneath forward section; 7) Bulkhead of the nose section; 8,9) Panels;
10) Rear part of forward section of fuselage; 11) Suction ring; 12) Suction tube;
13) Cockpit; lk) Seat; 15) Minor assemblies; 16) Front section of the fuselage in
assembled view.
4.
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:_juse of highly mechanized means for rivet* and for.the form n atio of the holes by
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.drilling and by dimpling, to form a cavity underneath the rivet head; this makes it
Table 1
Exaktples of Riveted Assembly Work
Riveted '"
components
.
Nomenclature of minor
.,----
units, panels, and
major assemblies
Sketch
,
,
,
Minor
assemblies
and panels
Ribs, bulkheads, long-
erons, and other small
assemblies
40
. 1/
110i:
,
Panel lining of the wing
and fuselage, joined from
several plates or panels
power tools, flaps,
etc.
'
.
ill
:.40r
"I
Major
Assembly
units
'
Front and rear sections
of the fuselage, wing,
tail group, etc.
..... 13
AO=
.
ill ?
.
lip .
.
.a ... . .
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'possible to organize the work on a continUous basis by moving either the workpiece
.or the equipment.
Major assembled units, in a technical and structural sense, represent finished
.prarts of the mainproduct. They are characterized by requiring a comparatively large
..amount of assembly-work and considerable labor, using specialized equipment for
?
drilling holes and for riveting. Such units are of relatively large size and are
characterized by an intricate design.
Depending on the nature of the parts involved in the assembly by riveting, a
distinction is made between the assembly of minor and major units. In the assembly
of major units, individual minor assemblies and panels are joined by means of spe-
cialized rigs, with the result that a larger assembled unit is formed(such as a wing,
center section, fuselage, tail group, hermetically-sealed compartment, and so forth).
The minor and the major assemblies then go to the final assembly, where the
combination of the separate units takes place along with other components, and with
the installation of conduit wiring, instruments, and other necessary parts.
1. Methods of Assembly
Riveting work, by means of whibh separate parts are united with rivets into
minor assemblies and panels, and these assembled as section and major units, may be
reduced to two operations ; namely, the placing of the parts in the proper position
as specified by the drawings, and their joining together by riveting.
Depending, however, on the particular methods of production which prevail in
any one plant, there ray be more operations in addition to the two basic operations
-stated. Such additional operations in actual production, as a rule, deal with the
.lining up and supply of the parts, marking off for drilling, etc. (Fig.3). Much
time is lost in the performance of these operations, and, furthermore, highly ex-
perienced workmen are needed.
The difficulties mentioned can be eliminated by adopting a method of assembly
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whereby the parts to be assembled are prepared, with the holes drilled by means Of
templates in special jigs. The schedule on procedure of assembly by this method is
shown in Fig.4. By this method, the number of operations is reduced to three.
a)
b)
-Or
c)
-10
-4
e)
Fig.3 - Schematic Diagram of Sequence of Operations When Using the Pro-
cedure of Narking Off and Laying Out Work
a) Layout, dimensioning, and marking; b) Supply and arrangement of parts;
c) Arrangement in assembly position and fastening; d) Narking off for
drilling; e) Drilling; f) Riveting
The advantage of assembling by previously drilling the holes in the parts while
still in the fixtures, and using proper templates as guides, lies in the fact that
the parts, when placed together, will fit
accurately. To effect a more perfect
riveted joint, guide holes are drilled
only in one (the inside) mating part, the
number of which must be the same as the
number of rivets in any particular joint,
while in the other mating part (the out-
side) 2-3 holes are drilled, which must
coincide with the 2-3 holes in the inside
piece used as guide holes. Increasing the number of guide holes (above 2-3) is of
no use since this reduces the probability of coincidence of a larger number of hole
in the assembly of the mating parts.
During the assembly of minor and major units in suitable fixtures or jigs, the
a)
b)
c)
Fig.4 - Sequence of Operations When
Assembling from Guide Holes
a). Arrangement in assembly position and
fastening; b) Drilling; c) Riveting
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--parts are arranged in accordance with the guide holes or by means of the holding
- devices-whtdrare a part of such fixtures.
44 The adoption of the method of assembly on the basis of guide holes is quite
--rational; since this procedure requires less assembly equipment, simplifies the con-
c.
Istruction of the equipment, increases the quality of the work, and permits better
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?!utilization of labor. However, this method is not sufficiently precise for the
- correct installation and fitting of linings and assembledcomponents, specified for
4
--the exterior of an aircraft. For this reason, it is customary to adopt a method of
_..assembly of such parts in fixtures, taking as a guide the outline of the exterior
- surface of the lining or the parts of the airframe.
- 2. Characteristics of Assembly Equipment
Depending on the variety of parts and items used, assembly equipment may be
- classified as being of the following types:
1) Equipment for the assembly of minor units and panels;
2) Equipment for the assembly of major units and their sections.
Fixtures or jigs of the first group are of comparatively small size, of simple
- construction, and permit ready access to the workpiece.
Figure 5 shows a typical construction of a fixture for the assembly, drilling,
- and riveting of minor units such as ribs and bulkheads. In order to make the work-
- piece accessible from both sides, the fixtures shown are reversible. The fixture
- is built from standardized units and parts.
In some of the designs the raising and turning of the unit in process of asserr-
'bly is accomplished by means of pneumatic jacks, incorporated in the design of the
-.fixture. A similar type of fixture for drilling holes in rib joints is shown in
Fig.6.
The assembly of the wing panels, center section, fuselage, and other major
units is accomplished in fixtures having a more intricate structure.
8
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Fif.lure 7 shows a fixture for the assemb17 of wing panels. The sheeLs and the
strin7ers are placed. in the fixture and pinned with control rivets, after wUch the
- Tical Construction of a Fixture for Asserbling, Drilling and
Riveting of Airplane Ribs
work of drillire; the holes, countersinking, dimpling, insertion of the rivets and
group riveting is carried out. Then, the riveted panel is returned to the same fix-
ture for installation of the transverse elements which impart stiffness.
Fixtures and jigs of the second group for the assembly of major units and their,
sections have relatively more complicated working parts and are of larger size; they
are also more expensive to build. Some of these fixtures, intended for assembling;
drilling, and riveting of sections of the fuselage and wings of aircraft are shown
in Figs.8,9, and 10. These jigs are used for assemblies of major units from previ-
ously assembled minbr units and panels, installing supplemental elements 'to ihipart
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stiffness; hole drilling, countersinPinf: or limplinr, and riveting.
1 ti
As a means of correct alignment of the parts in the fixtPre, either tLe surface
cortour of t!'e linor asserh17- un::.ts or the
wLich have been -Tevious17
drilled in accordance with a pattern or
template, ray be used.
In alinning the parts in accordance
with the contour of the surface, use is
rade of the 1oldin7 and clamping devices
with which the fixtures are usually pro-
vided, some of which are shown in Fi7s.11
and 12.
The holding devices shown ir
used for the alignment of corponents in
fixtures, are corronly known as braces,
- INpuble-Sided Swininr Fixture
channels, and clarps.
for Drilling Holes in Rib Joints
It is obvious, therefore, that in
order to do a good job of riveting it is necessary to have man:, specialized rigs,
whose construction consumes much time and requires considerable material. The ex-
pense is particularly large when a new type of aircraft is scheduled for production.
For this reason, in the construction 'of assembly jigs standardized parts and com-
ponents are used as much as possible, and these ray be changed around and moved from
one location to another to accommodate the requirements of different desirns of
.structures.
To attain this objective with a vinimum loss of time and at a low cost,
is one of the chief problems facing the machine designer and builder.
The following basic principles must be observed in the development, design and
construction of jigs:
1) Not to use components Made up from parts by welding or riveting, and as far
STAY
10
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Fig.7 - Assembly of a Ming in a Jig
Fig. 8 - TYpical Design of a Jig for Assembling, Drilling, and Riveting of a Fuselage
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FiE.9 - Ji E for the Assembly of FtselaEe Sections
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as possible to use components which may be taken apart by removing and replacing
bolts and nuts. This permits the repeated use of the components in various types of
fixtures for many different purposes.
2) Endeavor to use standard parts whiCh will permit their interchange in differ-
ent types of fixtures for the assembly of light, medium, and heavy-duty units.
3) Make the component parts of the assembly jig from materials of the lowest
cost that will serve the purpose. In particular, make wide use of iron castings and
of plastic materials, which results in lower cost as compared with rolled steel
products.
Assembly jigs built in accordance with these principles from standard castings
are shown in Figs.13, 1/4.1 and also in Figs.5 and 8. ,
The introduction and use of assembly fixtures of standardized construction in
industrial plants permits to accomplish the following:
1) Shorten the time and lower the cost of getting set up for the production of
new models of structures;
2) Reduce the amount of work involved in the project by means of proper design
of the jig;
3) Reduce the amount of work involved in the construction of the fixture.
In order to improve the working conditions in the place where assembling, drill-
ing and riveting is 'done on large units, platforms are provided-for the workmen,
along with compressed air lines (Fig.15) and electric current for extension lights.
Every fixture is provided with valves for connecting the compressed-air hose to the,
various pneumatic tools (such as drills, hammers, portable presses, tapping tools,
etc). Several valves are located at various points of the fixtures, so that the
movements of the workmen will not be hampered by hose lines of greater length than
necessary. Usually in fixtures of large size, compressed air is available at the
upper as well as at the lower levels of the fixture.
Large assembly jigs are provided with working platforms and ladders to permit!,
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Stringer Spar
Fig.11 - Some of the Holding Devices for Mounting to Assembly Fixtures
a) Extension-type clamp; b) Screw-type support; c) Adjustable and re-
versible clamp; d) Swivel clamp
Fig.12 - Several Types of Holders for Mounting to Assembly Fixtures
a) Clamp with lock pin; b) Clamp with eccentric cam lock; c) Remov-
able clamp with eccentric lock; d) Removable brace with lock pin;
e) Collapsible double-flap brace
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- Jig ::ade of Standardized Components for the Assembly of
'ling Center Sections
Fig.14 - Jig Made of Standardized Components for the Assembly of Panel Sections
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Fig.15 - Outline of a Typical Coirpressed-Air Installation on Assembly Jigs
' a) Compressed-air line
Fig.16 - Jig for the Assembly of Wings, Equipped with Platforms to Facilitate
Work on the Higher Levels of the Structure
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4work on the elevated parts of the structure (Fig.16). Figure 17 shows a typical
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design of a movable platform. In this design standard parts are used, which may be
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E
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Fig.l7 - Kovable Working Platform
readily joined together and permit the rapid assembly and disassembly of the plat-
'form, adapting it to the requirements of various fixtures.
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Chapter II
MEANS FOR OBTAINING SURFACE SMOOTHNESS OF MAJOR UNITS
1. Stretching of the Planking
A high degree of surface smoothness is required for the streamlined parts of
aircraft, exposed to the air flaw. Defects in the form of peeling and buckling,
produced by improper work during the technical process of assembly and riveting, de-
crease the aerodynamic quality of aircraft to a considerable degree.
To prevent the development of peeling and buckling of the planking, which may
arise as a result of loose contact with the airframe, special tightening methods are
used during the assembly in fixtures. For sheets of light gage (thickness less
than 0.8 mm), mechanical or thermal stretching of the planking is used, which is
done before drilling the holes and riveting.
The mechanical stretching of the skin of the airframe is accomplished by using
stretchers and rubber buffer strips. The sheets are fastened on one end-to the'-di-r"--
frame, the shock absorbers are placed on the upper surface, and this is followed by
tightening the stretching device. After that the holes are drilled and. the clamps
and braces adjusted, so that the sheets are in intimate contact with the airframe.
An effective method of preventing peeling after riveting, is to stretch the
sheets on the airframe before riveting, by using the thermal method.
In the thermal method of stretching, the sheets are heated in a special elec-
tric heating device to a temperature of 70 - 80?C. On heating, the sheets increase '
in length and width in accordance with the coefficient of expansion. During the
18
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subsequent cooling to ambient temperature, the sheets contract and thus become
stretched tightly on the airframe.
Stretching by means of electrical heating is effected in the following manner:
The prepared sheet is first placed on the airframe and is fastened either on the
Fig.18 - Stretching of the Planking on the Airframe by
Means of Shock Absorbers
upper or lower end with three to four rivets. Then the heating device is installed
and the current turned on. On reaching 80?C (usually in L. - 5 min) the sheet is
tightened on the opposite end with six to seven rivets, thus fixing the sheet in the
proper position. During all the time of fastening the ends of the sheet, it is
necessary to maintain the temperature of the sheet constant, with a variation of not
more than 5?C. Having riveted the sheet on the ends, the heating device is dis-
connected and the sheet allowed to coql to the ambient temperature. Next, the holes
are drilled and dimpled for the rivet heads, and the riveting is done.
When it becomes necessary to dimple the holes for the rivet heads, additional
operations become necessary, namely,
1) After the sheet is cooled, it is removed for the purpose of dimpling by
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2) After stamping of the recesses is completed, the sheet is again installed
on the airframe, during which time it is once more heated electrically in accordance
with the procedure described above.
Heating devices are available in two types: devices with nichrome spiral
elements and devices with bulb panels.
Nichrome spirals wound on
alit eCtigt WU t I IA
a cc& t tgatt.t Oft INC tif C
Mfg Ctlfitt( ft CUM ilf ff
rcit.m"t"".tfl
ttft(11A(taailll
p.
spiral tubes are placed at the focal point of a
reflector (Fig.19). The inside of the
reflector is coated with aluminum, which
has a high coefficient of reflection. The
number of required reflectors is deter-
mined by the size of the sheet to be heat-
ed. All reflectors are mounted on one
panel, so that the shape of the panel must
correspond to the configuration of the
sheet exposed to heating. The heating
panel is fed with alternating current from
transformers at a potential of 20-30 v.
The basic wiring of the electric heating
device is shown in Fig.20. The panel con-
taining the heating device is mounted near the assembly jig.
The panel is moved from one place to another as may be needed, by means of a
suitable movable carriage suspended from a monorail which forms a part of the jig
(Fig.21). The spacing between the panel and the sheet. is regulated by suitable
props.
Measurement of the temperature during heating is done on the opposite side of
the sheet, i.e., from the airframe side, by means of a thermocouple.
It should be noted that in the process of heating, the lower part of the sheets
heats somewhat slower than the middle and upper parts (Fig:22). This is causESTAT
Fig.19 - Interior View of the Device for
Heating the Sheets with Nichrome Spiral
Wire as Heating Elements
20
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1
1
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the fact that the lower section of the sheet is, being cooled by the current of cold '
air from below (according to investigations by A.N.Belikov). In order to eliminate
Fig.20 - Basic Electrical Wiring
Diagram of the Heating Device
a) Heating wires; b) Knife switch;
c) Transformer
this undesirable effect, it is necessary
to take it into consideration in calcula-
ting the design Of the heating device, and
to provide for a higher output of heat
energy for the lower part than for the
upper. Nonuniformity of heating the sheet
may be avoided by regulating the spacing
of the reflectors from the exposed sheets.
When the sheets are heated by means
of bulbs, and not by spiral resistance
elements, the bulbs are arranged in
checkerboard order, thus ensuring uniform
heating of the surface of the sheets.
The thermal method of stretching is
used in parts of the plant for the assem-
bly and riveting of the wing center sec-
tion, stabilizers, tail fin, and Other sections which require thin sheet covering.
The application Of this method has a wider significance in connection with the in-
vestigation of the influence of the temperature factor on the surface, on the mechan-
ical properties of the materials of the skin and airframe, the degree of deformation
of the airframe, and the susceptibility of the materials to intercrystalline corro-
sion. Wider application of the thermal method of stretching is tied in also with
the research work being done on finding more perfect means of' exposure of the com-
ponents to heat, to shorten the time of heating, and also on the development of more
precise technical processes for obtai4ng a higher quality of product at a lower
cost.
21
STAT .
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d
9 I
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A more effective method,
which ensures the required aerodynamic smoothness of
surface, is the assembly from the outline
(of the planking), applying the correct
engineering design principles of compen-
sation.
Fig.21 - Heating Device, Transported
Along the Fixture on a Monorail
2. Means for Temporary Fastening of Parts
After the parts are arranged in the
required position and the sheets are
stretched on, and before the holes are
drilled for riveting, the adjoining parts
are fastened by means of spring clamps,
clamps with hooks, adjustable bolts, screw clamps,-glue, or other means.
Of all available means for temporary fastening, the most widely used and the
e
4`If. ? I.
Pr :'
,
74"Irf i .
::
:4
r i-- 4.--I? --t-
: * ifr: . i 1 e 1 .
-I- -?-:&4.,..R.L*-4.-A.:
:6141.#11s.?..ao.igs.,,,,,,,,,A ;27.4 4.,v 133_ !..x pg, 4: ,
trof Row
roPoitit / 7 13 19 25 31 37 43 2 8 14 ZO 26 .32 38 44
T 8382869090908880 8$8891791929290811
A
9 15 1 7 33 30 ,t?P
82 82 82 84 83 84 83 81
Fig.22 - Temperature at Different Points on the Sheet After Heating for
Four Minutes with Infra-red Rays
22
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STAT
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most effective, is the spring-type fastener, type PF (Fig.23). Assuring a tight
contact of adjoining parts, they can be moved quickly and easily in place and as
quickly and easily removed.
Spring clamps are installed in holes
IV IT
drilled simultaneously through two or more
WWI 'Ic=);"7 parts which are to be joined together.
#
Fig .23 - Spring Clamp of Type PF
The number of clamps required is deter-
mined according to the shape and size of
the parts on which the work is done.
Installation and removal of the
and Its Parts
clamps is done by means of the type K-1
1) Body; 2) Cover; 3) Guide pin;
pullers (Fig.24).
4) Wedge; 5) Spring
Due to the rather low compressive
force of spring clamps of the PF type, it is recommended that they be used only in
clamping sheets which do not exceed 2 mm in total thickness. When the combined
Fig.24 - Installation of a Spring Clamp by Means of Pullers Type K-1
1) Installation of clamp by means of pullers type K-1; 2) Original position '
of clamp; 3) Extended position of the, guide pin and its entry in the hole
(puller in compressed position); 4) Wedge of guide pin in position for fasten-
ing; 5) Working position of clamp with puller in released position
thickness is greater, and also in the case of cambered surfaces, adjustable bolts
and adjustable control rivets are used at a spacing of 150-300 mm. In cases wliffA.T
23
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11,?
'157.1,1102:99=274=1
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CI?
OM.
the parts joined together are not to be taken apart again, the control rivets should
have the finished-size diameter, in accordance with the specifications on the techni-
o 5i o4'4 ?z3 of 3 053 05;
O 0 0 0 0 ? 0
0173 0/03 o84 o73 o 3 3 'on;
o o o o o . o
0183 all 014 i o1.73 o/54 0/73
o o o o o o
oN3 0223 024 o153 024 024
o o o o o o
0343 0283 0264 024 0271 021
0 0 0
0
0
0
C
0
?
0
0 ?
50...1:b..0
?
? ?
? ?
? ?
? ?
? ?
?
? ?
? ?
? ?
?
?
Fig.25 - Outline of the Sequence of Drilling the Holes, Installation
of Clamps, and Riveting by the Terminal Method
- cal drawings.
For the protection of surfaces of the parts, especially of the planking, from
possible damage while installing the adjustable bolts, it is advisable to use washers
rade from nonmetallic naterials.
3. Order of Clamp Installation and Sequence of Drilling Holes and of Riveting
Peeling and buckling of the surface of riveted parts may develop as the result'
of the improper sequence of installing clamps, holders, and control bolts, or of
wrong procedure in drilling holes and in riveting. For this reason, in the execution
STAT
of the mechanical operations it is imperative that the order in which the job is done
24
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in accordance wit.h t.hc. .0 - - ? ?
Fig.26 ? Example of the Sequence of Riveting of Planking by the Terminal Method
:8s 0of 0 51, 00
o \\.0 o / 0
o 2f 0f4 34,
0 . 0 . 0 . 0 g
O 0 0
?I2f 0?1?1 54 :"4
O /0 0 \ o
0/51 NI 013, off ,
? r o r 0 t o t
V 41 41 41 2,1
Fig.27 ? Outline of the Sequence of Drilling of Holes, Installation of STAT
Imps, and Riveting by the Central Method
25
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,
-lis in accordance with the specifications.
-71
In order to ensure smoothness of the surfaces, the installation of the clamps
and holders as well as the riveting opera-
tion should be carried out either by the
"central" or the "terminal" method.
The terminal method (Figs.25 and 26)
of drilling holes, fixing of clamping de-
vices, and riveting is characterized by the
fact that the assigned job is done from the
fastened end or side of the sheet toward
the free end.
The central method (Figs.27 and 28) of
drilling holes, fixing of clamping devices
and riveting, is characterized by the fact
that the operation is carried out from the
center toward the periphery. ,
Riveting by the Central Method
The application of the described me-
thods results in better stretching of the sheets and prevents possible buckling on
the surface of the planking.
Fig.28 - Example of the Sequence of
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?
,
?
CHAPTER III
- ,
CO1TARISON OF RIVETING 'JIM OTTER /TANS OF JOINTING
Structural elements which are intended to be fastened together in assembly jigs
may be joined by means of riveting, welding, or cementing. To evaluate these differ-
ent means of jointing, some of the most important characteristics of each will be
described below.
The wide application of riveting of light metal alloys involves a number of in-
herent disadvantages, among which the following are of importance: increase in
weight of the structure due to the weight of the protruding head of the rivet; weak-
ening of the material being riveted due to the necessary drilling of the rivet holes,
which may betas much as 25%; large number of operations necessary in the preparation
of the materials for jointing, such as. the procurement of rivets, drilling of holes,
and countersinking or stamping of recesses, insertion of the rivets, and the riveting
itself; the objectional noise of the pneumatic riveting hammers; and other disadvan-
tages.
In order to avoid, these disadvantages, efforts are being made as the first step
- to improve the process of riveting, and secondly to replace riveting by other methods
of making permanent joints, such as electric spot or roller welding, cementing,
. soldering, etc.
In the present state of technical development of making nonseparable joints,
only spot and roller welding may be considered as being comparable to riveting. The
introduction of these methods is facilitated by the fact that welded joints calsTAT
27
'a.
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,
-
considered as equivalent to riveted joints with a large number of riveted seams, with
respect to the appearance of the seam itself. and to the character of the welded
spots.
However, in the manufacture of aircraft, spot welding has not been widely a-
dopted, Much is explained by the lack of
reliable analytical and experimental data
on the naterials thus welded, from the
viewpoint of strength and reliability as
well as of the technical perforrance of
the job of welding the joints.
Fundamental properties character-
izing riveted and welded joints, include
relative strength, quality of the surface,
and also technical and economic consider-
b) Humber of Repeated Loads in Thou-
ations.
sands; c) Joints with Rivets of Type 3K;
d) Joints with Rivets of Type 3Y-90?
well known, is determined by the dimen-
e) Spot-Welded Joints
sions and by the mechanical properties of
its molten central core. If the welding time is too short or the current too low,
no molten core may form. The strength of a weld that is thus insufficiently heated
is low. By-comparison, the strength of a riveted joint is determined by the mechan-
ical properties of the material from which it is made and by the quality of riveting.
t0
48
a)a6
44
0
4 8 12 16 20 24
b)
Fig.29 - Performance of Joints at
Cyclic Static Loading
a) Coefficient of Loading Stress;
The strength of a spot weld, as is
Thus, the strength of a spot weld and of a rivet in its original condition, is
a function of the technical process of welding or riveting.
Furthermore, the strength of welded and riveted joints is determined not only
by the strength of the spot welds or of the rivets, but also by the mechanical prop-
erties of the materials being joined, the distribution and arrangement of the points
where the joint is made, the number of points, and also by a series of other csTAT
?
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r ?
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_structional and engineering factors.
_
-
"
Investigations carried out by V.P.Grigortyev on the strength of welded joints
with static, vibration and with cyclic stress loading, show the following;
.1. Under conditions of static and vibration stress, structures of welded and of
riveted joints have equal strength.
2. Under conditions of cyclic static loading, welded joints do not, stand up un-
der service conditions as well as riveted joints (Fig.29).'
3. The slip or displacement in shear, during the transition from the elastic to
the ductile condition, is lower in riveted than in welded joints (Fig.30).
a)
C)
15
I0
0
F
2.5
14-.4..1 +7
,4:1i4.11 -1
Itti
Li
7.5
10
Fig.30 - Slip in Welded and in Riveted Joints
a) Welded joint; b) Riveted joint with rivets of 4 rm and with protruding .
heads; c) Riveted joint with counter-sunk heads having a diameter of 5 mm
and a conical angle of 90?.- The rupture takes place along the dots.
1) Stress in kg/mm2; 2) Slip A in-% of diameter from the spot weld;
3) Strong joint; 4) Extra strong joint; 5) Slip 'A in % of diameter of rivet;
6) Slip A in % of-diameter of rivet
?
29.
STAT
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The low ductility of welded joints causes une4tal strain distribution on the
row of spot welds. The first row, at the extreme edge, absorbs most of the load,
with the result that on stressing the seam or joint with equal or with greater load-
ing of 0.7 Pl, cracks appear in the first row, which leads to a rupture of the joint.
Under similar conditions, when the load is applied on rows of a riveted joint, the
first row of rivets absorbs the stresses and relieves the tension throughout the
sheet. On the whole, a greater amount of work is involved in making joints that are
subjected to stresses on cyclic load ap-
plication.
The quality and condition of the
surface of riveted and of welded joints
is characterized by the extent to which
ITAtt
the heads of the countersunk rivets pro -
ti.ude or by the depression of the spot
,
414, welds in relation to the surface of the
part, and by the degree of warping of a
portion of the joint or of the assembled
-f unit on completion of the joint.
It should be noted that the smooth-
ness of the surface of an assembled unit
Fig.31 - View of Investigated Panel
depends not only on the proper riveting
or welding operation, but also on the accuracy of the contour of the airframe. A
comparatively thin planking will follow the depressions and roughnesses in the air-
frame so that the smoothness of the surface is disrupted on some parts of the assem-
bled unit. Therefore the. quality of the finish of the airframe, the corresponding
supply of separate parts, and the proper execution of the technical process of riv-
eting or welding contribute to the quality of the surface of individual units as
well as of the aircraft as a whole.
30
STAT
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ConSiderable expenditure of labor is involved in meeting the quality require-
ment of surface smoothness in connection with riveting.
In the riveting of structures it is possible to limit the protrusion of the
rivet heads to one tenth of a millimeter, due to the close correspondence of the
dimensions of the head of countersunk rivets with the dimensions of the countersunk
or stamped recesses of the hole. In the case of welding light metal allOys, the
cavities formed by spot welding may vary from 0.05 to 0.3 mm.
For the purpose of investigating the technical economic aspects of riveted and
welded joints on a comparative basis, a study was made of the panel shown in Fig.31,
which was produced by riveting and also by welding. The panel is covered with a
planking Of 1.2 mm thickness of D16T alloy, and a frame consisting of stamped ribs
of the same material. In all, the panel contains 1363 rivets (or spot welds).
The data given in Fig.32 show that the time consumed in making the panel by
welding is less than that needed for riveting. The number of auxiliary units of
equipment used in a working shift to make up these panels was 12 in the case of riv-
eting each unit separately, and 15 in the case of welding. The space occupied by the
welding machine was larger by 15-20% than that required by the riveting press. The
power consumed by the welding machine to weld 100 panels in one shift Was equal to
1300 kw, as compared with-35-46 kw required for riveting by pneumatic riveting ham-
mers or presses. The considerable cost of welding machines and the larger mainte-
nance expense involved result in higher cost of unit production.
These statements yield the following conclusions:
1. In assembled units subjected to static loads, welding may be considered as
being equivalent to riveting.
2. Welded joints are not suitable for use in structures subjected to cyclic
stress loads.
3. The degree of surface smoothness of riveted and of welded joints Should be
# approximately the same.
,
31
STAT
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4. Spot welding results in a higher rate of production than riveting with pneu-
matic hammers or individual press riveting.
a)
b)
Fig.32 - Technical-Economic Aspects in the Manufacture of Panels by
Riveting and Welding
a) Riveting with pneumatic riveting hammers; b) Press riveting (single
units; c) Electric (spot) welding; d) Piecework time for one panel, in
min; e) Machine-work time for one panel, in min; f) Cost of one panel, in
rubles; g) Number of auxiliary equipment to produce 100 panels during one
shift; h) Power required by the machine tools, in kilowatts, to produce
100 panels during one shift
In order to make welding more advantageous economically, it is necessary to re-
duce the power consumption and the size of the welding machines, while further im-
provements and refinements in the technology of wel4ing may permit joints of higher
strength and smoother surface finish of the assembled units.
32
STAT
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.."
PART II
PREPARATION OF THE HOLES AND COUNTERSINKING BEFORE RIVETING.
PLACING OF THE RIVETS
CHAPTER IV
FORKATION OF THE HOLES
1. Method of Producing the Holes
The production of holes is a preliminary operation to riveting. The quality of
the riveted joints depends much on how well the operation of preparing the holes was
carried out. In the performance of this operation the following conditions are nec-
essary: clean inside of the hole (freedom from graininess, burrs, scratches, etc.),
perfect roundness, no skewing, and absence of other defects.
Holes in parts intended for riveting are made by two methods: drilling or
punching.
Punched holes are widely employed in assembly work of sheets, plates, and other
profiles, and are made in special instruments (punching presses) by means of punches
? ;and dies.
Holes rade by punching possess a number of disadvantages, the principal ones
being as follows: buckling of the material, hardening by cold-working, cracking,
torn edges, etc. Cracks and torn edges cause additional stresses in the joint. For,
this reason, the strength of structural elements with punched holes is lower than
:that of the same elements with drilled holes. ' Depending on the material of the
structural elements, the reduction in strength is from 2 to 8% (Table 2).
The strength in fatigue tests of structural elements with punched holes is from
L.
3 to 8% lower than with drilled holes (Fig.33). STAT
33
d
".)
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?
- orreval -034 ???
The difference in the strength of plates with punched and with drilled holes is
particularly noticeable on repeated static loading tests. The strength of a plate
Table 2
Strength of Plates with Holes Made by Different Methods
Strength of plate in %
Method of forming the hole
V95
MA-1
D16T
Drilling to size
100
100
100
Punching to size
88
96
92
Punching holes to 0.75 diameter
followed by drilling to size
100
102
99
with punched holes is 1.5 times less than that of the same plate with drilled holes,
when subjected to repeated static loading. For this reason, the punching of holes to
15
$4 ? 1111 1 I
15
4441/tits PPF40 M 4 Itie Z?Nri.0417
1
a)
- b)
a ....A aies fiL
FI i?tof
c)
Fig.33 - Effect of the Manner in Which the Holes are Made on the
Strength of the Plate in Fatigue Tests
a) Drilled holes; b) Punched, holes; c) Number of cycles
the exact final diameter is not good practice..
?
? 34
STAT
The preliminary punching 'of holes to
';;?,1
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' -re'sx;????
?MT:
e
?
?smaller diameter for use as guide holes or for assembly, should be done in sections
n:la
?
_lof the plant that are properly equipped with punching and stamping equipment. Before
_jthe final assembly of parts, components, or major units, the punched holes are drill-
Jed to size to correspond with the diameter of the rivets used.
Standard equipment is used for punching holes, utilizing punches and dies and
Fig.% - Press for Punching Holes
punch presses. One of these presses is
shown in Fig.34. In setting up the press
for punching, templates or patterns with
markers are used, the distance between the
markers corresponding to the position of the
holes in the part being punched.
The punching of the holes may be done
in devices, such as the one shown in Fig.35,
in which the'frame has the shape of the
letter C.
The holes are made-by the punch (1) and
the mating die (2) (Fig.36), between which
the work to be punched is placed in position.
Drilled holes assure a stronger and
more stable joint, due to the cleanliness and greater precision in the drilling op-
eration.
Depending on the construction of the components and the thickness of the parts
-being riveted, drilling may be done (a) in one, or (b) in two operations:
a) Drilling to final dimensions from the side of the planking or the airframe;
b) Preliminary drilling to a smaller size from the sid of the airframe, fol-
lowed by drilling to exact size from the side of the planking.
Drilling of the holes for riveting from the planking side to finished size is
done by means of templates or in special jigs through guide bushings or according to STAT
35
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r 44
'It,
r
? ? r'.,t
;??;:".-?????
layout marks.
'
, VrIks 4:4-?
%In the constructionof aircraft'the-most widely used method is to drill holes-
withithd aid of templates made of steel.
? ; ? , 4, ?
V ?
14
?? ;
1, ?
i r.it
? se
, ? ?
!
Table 3
Dimensions de abd D when Using Guide Bushings
.
'
?
Sketch
.
Diameter
de of
hole
Nominal
2.7
3.1
3.6
4.1
5.1
6.1
8.1
9.6
10.1
Permissible
deviation
+0.1
+0.15
+0.2
i
,
4
. ,
,
.
Outside
diameter
D
.
,
Nominal
5
6
7
8
10
12
16
18
20 ,
Permissible
, '
=0.2
,
.
-0.3,
.
- ?
B
.
.
?..0
?
."deviation
t
To preserve the templates and prevent wear and tear, the guide holes consist of
hardened steel bushings which are inserted at the proper places in the template, with
( -- the drill passing thrOugh them. These inserted bushings, ,however, may loosen and
A-:-1 Y
..V4 ?
A
, 15. .?
shift, l or even drop out. For this reason it is worthwhile to use patterns without
!%11?
... : t
. ,.
- d,i ,,??? ,1
15 ( :
? a? - ' - . 't .1 A
.
; ?
? ? ?? , i ,, 4 1 11
- . tr
. " _ .?
4 t
, ::,?
,
plates may be done aS liench work
Press
inserted bushings and to rely on special
fittings or bushings placed On the drill
(Fig.37): '
Such special drill bushings are inter-
.9hangeable. Depending on the diameter of
the' drill they have specific dimensions
(1.,. j ? ? ,
, ?
? (Tab10). :
Drilling of holes 'With the aid of tem-
or in special fixtures which permit placing aasTAT
. ,
L {.
.?
r?'
, A t" 19
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?
fastening of the template to the'tpart beinedrilled. Should difficulties be encoun-
tered in applying the template when drilling is done in fixtures, special guides are
Fig.36 - Jig Used on Presses for
Punching Holes
a) Punch; b) Die
30% as compared with
used, which may be laid over the workpiece
or mounted to the part before drilling
(Fig.38). The special guide usually con-
sists of a steel plate in which bushings are
inserted with force fit. After assembly and
fastening of the parts in the fixture, the
special guide is put in place, fastened, and
the holes are drilled (Fig.39).
When drilling in accordance with pre-
liminary prepared guide holes (Fig.40), the
work involved is reduced by approximately
drilling when the holes are merely marked on layout. When a
template is prepared with guide holes for drilling a particular part, it is obvious
Fig.37 - Drilling Holes by a Template
a) Template; b) Bushing; c) Parts being drilled
that it may be used for drilling other similar parts.
Drilling of holes by marking (Fig.41), is used only in exceptional cases, since
it results in a low rate of production, and is justified only in experimental work.
STAT
The laying out of spots can be done as follows:
a) Using a template and 'a center punch;
37
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?
.;
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y
- - _
?
"
- _
? ".? ` ?
Fig.38 - EXamples of Guide Templates
a) Layout; b) Flap, mounted on parts of the fixture
? Fig.39 - Drilling with Guide Templates
a) Guide bushing; b) Plate; c) Part being drilled
Fig.40 - Drilling with Previously Prepared Guide Holes
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(410
b) Using a template and spraying paint in the holes;
c) Using marking and measuring tools (such as an ordinary rule and pencil).
The following procedure is used in marking by means of a template and center
punch: The template is placed on the top of the part to be drilled, the holes are
punch-marked, the template is removed, and the
holes are drilled.
- When the marking is done by means of a tern
plate and application of paint, the placing of
the template is the same as described above, but
instead of using a center punch, the holes are
marked by a colored powder applied by spray gun.
The marking of holes by means of an ordinary rule and pencil is done on alum-
inum alloy parts. The marking of duralumin parts with scribing tools or center
punches is not permitted, since the protective surface film of the metal is destroyed
when it is scratched or punched, and there is a possibility that corrosion may de-
velop.
Drilling of holes for rivets is carried out in either stationary or portable
--drill stands or by pneumatic and electric hand drills.
A'
Fig.41 - Drilling for Narking
2. Cutting Tool
The cutting tool used for drilling holes consists of a spiral drill. Drills
are manufactured of carbon and of high speed steel. In drilling chromium-silicon
_steel alloys, drills with hard-metal tips are used, which permits a cutting speed
twice that of the cutting speed obtained with drills of carbon steel.
The angle 2p shown in the plan view of Fig./,.2 is of great importance and affects
the efficiency of drilling. This angle is chosen to correspond with the require-
ments of the type of material being drilled (Table 4).
Improper grinding of the drill such as unequal bevel of the cutting edge:s-rAf
39-
r
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? _-r.j? ?
a difference in their length, interfere with the correct performance of the drilling
and causes enlargement of the hole (Fig.43). Holes of an enlarged diameter aggravate
Table 4
Significance of the Angle 2T, Depending on the Type of naterial tiorked
ilaterial worked
?
2cp in de7rees
Steel, cast iron, hard bronze-, duralumin
_
116-118
Silumin, babbitt
- 1E1.0
Brass, soft bronze
130
nayinesium, ebonite, celluloid
85-90
the working conditions of riveting and cause breaking of the rivet heads. In addi-
tion, when the holes are larger than neces'sar7 they are not filled with the body of
the rivet, which, in turn, leads to looseness (slipping) of the seam. For this rea-
son, drill grinding should be done by experienced grinders at a centralized location,
with systematic observance of the geometry of the cutting parts of the drill and
cleanliness of the grinding work.
. -The quality of the work done in drilling is affected to a marked degree by
the lack of rigidity of the spindle and the chuck as well as by the wobble of the
drill itself if it is not properly held in the chuck.
Actual practice-as well as experimental investigations show that, to main-
tain the quality of the drilled 'holes, the lack of rigidity of the drill, or its
tendency to wobble in the chuck, must not exceed 0.1 to 0.2 mm. The lower limit
relates to holes up to 10 min, while the upper limit refers to holes of a diameter
-1 above 10 mm.
"
?
Holes for rivets of various sizes are made with drills, whose dimensions are
given in Table 5. STAT
4.04.1.001.MIJIVACIA.M.011.???????
a
110
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-
""-t, 6445409ild&Tt it"
-
1?.
-
(to
This relationship of the diameter of the rivet to the diameter of the drill, as
shown in Table 5, permits proper insertion of the rivets in the holes and assures
Fig.42 - Spiral Drill'
a) Shank; b) Guide face (land); c) Flute; d) Cutting part; e) View indi-
cated by arrow A; f) Flute; g) Cutting edges; h) Nargin; j) Edg%of margin;
k) Rib; 1) Chisel edge; m> Land clearance; n) Lip clearance surface
0
.that, in riveting, the hole will be completely filled with the metal from the Core
u
.;
?
of the rivet. The correct selection of the drill size is therefore of great import-
ance. If the hole is smaller, the rivet will not go in and will have to be forced
in, with damage to the parts being riveted and with an unnecessary loss of working
time.
In places of limited access, where drilling of the holes is difficult with or-
dinary drills, use is made of extra long drills in accordance with Specificationq
STAT
COST 886-41, or special extension and angular types of fittings are used, a descrip-
(.9
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?
^
tion of which is given below.
3. Drilling Machines
. ?
Vertical drill presses of the general-purpose type are used for drilling the
holes along the length of longerons, ribs, and other parts and junctions. Their use
results in a high rate of production and in a
higher quality of work, as compared with pneumatic
hand drills.
For drilling straight-line holes in minor
and major units of an aircraft it is advantageous
to use drill presses equipped with multiple-spindle drill heads. Drilling a number
Fig.43
Table 5
Dimensions of Spiral Drills for Drilling Riveted Holes
(Dimensions are in accordance with Russian Specifications GOST 887-43)
Diameter
of rivet,
d, in mm
Diameter
of drill,
d, in mm
Over-all
length of
drill, LI
in mm
Flute
length,
_.- 10 of
drill in
mm
2.6.
3.0
3.5
4.0
5.0
2.7
3.15
3.6
4.1
5.2
65
70
75
82
95
-35
40
45
50
60
6.0
8.0
9.5
10.0
6.2
8.2
9.7
10.2
105
125
135
140
68 85 95
42
95
STAT
- - -
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-7-
t-
_
of holes at-the same time in group sequence results in an increase of production
several times greater than with single hole drilling.
Technical data on the characteristics of
multiple-spindle drilling machines are given in
Table 6.
Figure 44 show a drill press equipped with
a special four-spindle drill head for drilling
junctions of relatively small size. The head of
the drill stand has a row of gears which impart a
rotary motion to the drills held by the jaw of
the checks. A roller conveyor is attached to the
base of the stand for supporting the workpiece
during the drilling operation and permitting to
- Drill Stand with a
move the work, for drilling the next group of
Four-Spindle Drill Head
holes in a successive manner.
Figure 45 shows a drill stand with a twelve-spindle drill head. The head is
fastened to the stationary part of the stand on the spindle end (1). From the elec-
tric motor the rotary motion is transmitted over the driven tapered block -(2) and
the clutch (3) to the crankshaft (4.) and dog (5). The dog (5) then imparts a rotary
motion to the spindles (7) of the head. In order to prevent dynamic unbalancing,
the dog is provided with a counterweight (6) on the crankshaft. This kind of a head
makes it possible to drill holes in components and in parts at a continuous pace..
In cases where it is inconvenient to move the work over the drill stand table
because of the large size of the workpieces, (such as heavy longerons, wing panels,
and center sections) stands with-drill heads are used that can be moved from one
place to another across the part which is being drilled.
A drill stand of this type is shown in Fig.47, intended for group drilling of
STAT
holes in parts of considerable length. The bedplate (1) carries the carriage v.),
43
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CD
0
CD
CD
-0
CD
(/)
CD
CD
0
CD<
1:31h
7:1
CD
CD
CD
CD
0
0
? ?
C)
7:1
0
-0
CO
(E)
0
0
0
r.)
6.)
a)
Table 6
Drilling Data for Multiple-Spindle Drill Heads
MCA
MC-84
c)
d)
e) 5)
cp h)
i)
11
n)
1)
o)
30
20
4
4
2800
2800
? 40
? 24
18
30
3,2
3,0
650
?
1650 1400
1800
1750
950
1000
25
25
1220
a) Type of drill press; b) Sketch of press; c) Number of spindles; d) Greatest diameter of holes in mm;
e) Number of revolutions of spindle in rpm; f) Maximum torque permitted per spindle in kg-mm;
g) Shortest distance between spindles in rm.; h) Rating of electric motor in kw; i) Maximum permitted
force of feed when working all spindles, in kg; j) Dimensions of sections, in:mm; k) Height; 1) Length;
m) Width; n) Opening in press, in mm; o) Jaw; p) Sweep; q) Twelve-spindle drill-head press;
r) Four-spindle drill head press; s) Four-spindle combination drill and milling head press
CD
0
CD
(D
-0
CD
(/)
CD
(D
0
CD
7:1
(D
(T)
CD
(D
0
0
? ?
C)
7:1
0
-0
CO
(E)
co
r.)
6.)
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???- - ? ??
?
^
C?1 C`l
8
if)
8
1
1830
Lt)
?????
?.
cs3,
el?
It
?????
45
e?-?N
V.1
STAT
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_
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_
which carries the electric motor
(4) is placed on the tracks (5),
and the four-spindle drill head (3). The longeron
which permit regulating the height of the workpiece.
For the purpose of fastening the longeron, the
drill stand is equipped with a number of pneumatic
gripping devices (6), operated by an air valve
connected to the compressed-air system. The dis-
placement of the carriage, together with the
drill head, after one group of holes is drilled
5 to another, is accomplished by means of the hand
wheel (8).
Specialized drill presses of portable or
radial types are used for drilling holes in com-
ponents and major units of large size in contin-
uous production.
Figure 48 shows a stand for drilling the
panels of a wing. The overhead trolley (1) with
the radial drill heads can be moved while in a
perpendicular position in two directions over the
monorail (2) which is attached to the, uprights
(3). The rotary arm (9) with the drill heads can
be rotated about the column (6) through 360?. At
the end of the arm is the electric rotor (7),
which transmits rotary motion to the spindle (1.). The feed of the drill is effected
by means of manual lever (8).
On such stands it is customary to have several radial drill heads, for
Fig.45 - Drill Stand with a
Twelve-Spindle Drill Head
1) Electric motor; 2) Hand
levers for feeding; 3) Body
of the twelve-spindle drill
head; 4) Drill; 5) Workpiece
(edging of a longeron);
6) Table with supporting de-
vice
use by
a corresponding number of drill operators. Drilling is done in accordance with the
marked guide holes in stringers, but templates and patterns may also be used. Fur-
ther improvements in such drill stands should be along the lines of automation for
46
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STAT
Declassified in Part - Sanitized Copy Approved for Release 2013/04/12 : CIA-RDP81-01043R001900110002-3
(it
Fig.46 - Kinematic Diagram of a Twelve-Spindle Drill Head
1) Spindle of drill press; 2) Driven shaft; 3) Clutch; 4) Crankshaft;
5) Block; 6) Counterweight; 7) Spindle
7 1. 2
- ? -4., ,
Fig.47 - Drilling the Border Holes of a Longeron on a Drill Press
with a Movable Multiple-Spindle Drill Head
1) Base; 2) Carriage; 3) Four-spindle drill head; 4) Longeron in which
the holes are drilled; 5) Runways on which the longeron is placed;
6) Pneumatic clamping devices; 7) Hand wheel for relocating the drill
head; 8) Manual feed lever
4-7
STAT
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?
shifting the part being drilled or the drill heads.
Radial drill heads may also be used for. drilling holes directly in parts mounted
in assembly jigs. A suitable arrangement is shown in Fig.49.
The flexible arm, consisting of two steel castings, permits drilling holes over.
the entire area covered by the radius of the arm. When it is necessary to drill
6 rik
holes lengthwise over the entire longeron, the drill head, together with the column
and its base, are shifted to the desired place on runways.
Several radial drill heads are used at the same time for drilling holes in
longerons of considerable length (Fig.50), which are installed on trucks that run on
monorails. Such installations permit to work on large panels of wings, center sec-
tions, and fuselage, longerons of various sizes, ribs, and other major units of an
aircraft.
Considering that the major units of an aircraft consist of separate minor units
and panels in shapes that permit ready access to the part on which work is being
done, the application of group drilling by a crew of drillers is feasible, and the
following advantages are realized:
1) The amount of labor is reduced and the workmanship of the, holes is improved;
2) An assembly line on the principle of continuous production.can be organized,
7 with the riveting also being done by the group method, tlIps improving the entire
A
system of work in the assembly sections of the plant witll'ai.rhythmic output of prod-
uction.
Figure 51 shows a diagram of a stand with which it is possible to assemble,
drill, and countersink panels over the entire surface. The drill heads are so ar-
ranged that the holes can be drilled perpendicularly to the sufface of workpieces.
Rotation of the drills is effected by means of flexible spindles from a common drive
mechanism which is part of the stand.
4ic 4. Manually Operated Mechanical Drilling Tool.
Air
Manually operated hand drills are also widely used on assembly jigs in ai./ST ATt,
? MO,
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(!,
eurmwrarrematzentp.41:csamt.v...?
- Stand for Radial Drill Head for Drilling Large-Size Panels
a - Overall view;.b - Radial drill head
1 - Trolley; 2 - Monorail; 3 - Pedestal; 4 - Spindle; 5 - Radial drill
head; 6 - Column; 7 - Electric motor; 8 - Hand lever; 9 - Bracket
49
STAT
'
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?
+a-
?
_
Fig .49 ? Radial Drill Head for Drilling Holes into Longerons,
Fixed in the Assembly Jig
Fig. 50 ? Aligning of Radial Drill Head for Drilling
' Holes in Longerons
50
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. - - - -I -7,, - -
construction along with other power tools. These are pneumatic and electric drills.
In present day production, pneumatic hand drills are in wider use, which have
the following comparative merits: Pneumatic
2
Fig.51 - Schematic Diagram of a
hand drills are of small size and weight; a
feature of the power drive is that it permits
a gradual and smooth increase in the speed of
the drill, by controlling the pressure on the
lever connected with the air valve. When the
drill is overloaded by excessive feed pressure,
Stand for Assembling, Drilling,
the motion stops and breakage of the drill is
and Riveting Panels
avoided, while in the case of electric hand
1 - ease; 2 - Drill head; 3 ?
drills their windings may burn out and the drill
Panel being worked; h - Rock-
itself may be damaged. It is cheaper to operate
ing cradle bed
pneumatic hand drills than electric, notwith-
standinr7, tnat it is necessary to go to considerable expense in providing auxiliary
equipment of compressors and air distribution lines. Furthermore, pneumatic hand
drills are safer to use than electric drills.
According to tne construction of the 'power drive mechanism, pneumatic hand
drills are of two types: rotary and reciprocating.
Drills wit} rotary motors have the following main advantages over piston-type
motors;
1. The power of rotary motors per unit weight is considerably greater than that-
of piston types. For this reason, for the same power output, the weight of rotary,
motors is considerably less as compared with piston types.
2. The absence of slide valve mechanisms, crankshafts, and connecting rods in ,
rotary motors simplifies their construction ascoMpared with piston-type motors,
thus facilitatinr their manufacture and lowering the cost.
3. The operation of rotary motors is much quieter, due to the absence of recip-
STAT .
51
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de ?
rocating parts, and the mass of the moving parts is well balanced. This is of con-
siderable importance in connection with the drilling and countersinking of holes
which make rigid requirements as to accuracy of the diameter and quality of the sur-
face of the parts worked.
A drawback of rotary motors is that their efficiency is somewhat lower than that
of piston motors, which results in a high consumption of compressed air. However,
the design and construction of rotary motors is being constantly improved', so that
the better grades of such motors have an efficiency almost approaching that of
piston-type motors.
Outside of the condition mentioned; in the selection of a particular type of a
pneumatic drill, it is advisable to give preference to the rotary motor type.
Table 7 gives the technical characteristics of pneumatic hand drills in general
use, in connection with the drilling of light-alloy structural elements.
In drilling holes in parts of aluminum and magnesium alloys and also of mild
steel, drills operated at speeds up to 3500 rpm are used. For drilling in parts of
alloy steel (such as edges of lOngerons, tie components, etc.), use is made of
slow-speed drills at a speed up to 1000 rpm. Pneumatic drills, whose rpm exceeds
3500 and approaches 13,000, are used only in drilling preliminary holes of a smaller
diameter than specified in parts made of mild steel and duralumin.
Figure 52 shows the construction of the pneumatic hand drill type 0-2 for drill-
ing holes. up to 8 mm in diameter, in parts made of aluminum and magnesium alloys.
The hand drill D-2 has a pistol-type grip. with a starting Mechanism, and con-
sists of a motor, reduction gear, and three-jawed chuck. The air hose is connected
to the male coupling (1) for the supply of compressed air from the system. When
pressure is applied to the lever of the cock (3), the air by-passes the check valve
(2) and is admitted to the motor through the channel (4) in the grip handle.
The motor in the hand drill 0-2 is of the rotary type and consists of rotor (6)
to which movable vanes (7) are mounted. The rotor, together with the vanes
52
i5STAT
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I.
Table 7
Technical Characteristics of Pneumatic Drills
. a)
b)
c) -
d)
e)
f)
g)
h)
i)
i)
k) .
D-1
1
,
iln
111:-
.
/125x125
m
,
,
5
i
3500
0.20
.
5
0.3
0.8'
D-10
41143111?%
200x17C
6
13000
0.20
5
0.5
.
1.6
D-2
4110;;;41
235x14C
i
8
2500
0.25
.
5
0.4
2.0
SD -8
.
250x140
8
2000
0.15
.
5
0.6
1.8
D-120CCiti:=11:3441
390x150
15
1200
,0.75
5
0.75
3.5
a) Type of hand drill; b) Job application; c) Sketch; d) Purpose; e) Dimensions of part worked; f) Vaximum
diameter of drill, in mm; g) Revolutions per minute; h) Power, in hp; i) Pressure of compressed air in
atmospheres; j) Air consumption in m3/min; k) Weight in kg; 1) In open places; m) For drilling soft steel
w and nonferrous, alloys; n) For drilling alloy steel; o) In crowded places; p) In places of limited access
?
?
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Declassified in Part - Sanitized Copy Approved for Release 2013/04/12 : CIA-RDP81-01043R001900110002-3
???"'
Table 7 (continued)
"2.---".",-.--,"1=11.1- "" ? 'T ' ?
-?????????-n?--? ?
Cf1
9
CV
tr:
?412
Lt1
C"?
?
?4:
?
0
xr?
LIN
11"
tr?
111
?
0
ix\
C;
cr:
0
0
CV
8
CV
8
141
cr1
z
0
0
-L)
Cr1
0
c?i
CV
to
0
0-,
to
0
r?t
0
0
to
to
cn
54.
to
(r)
STAT
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Declassified in Part - Sanitized Copy Ap roved for Release 2013/04/12 : CIA-RDP81-01043R001900110002-3
? .! ` - ? -
1
/ft,
Gated in the stationary part of the motor, the stator (10), on ball bearings. The
rotor is in an eccentric position with respect to the stator, forming thus a
crescent-shaped chamber (8). From the channel (9), compressed air enters the chamber
(8) between the rotor and stator and exerts a pressure on the vane (7), forcing the
rotor to rotate. As the motor revolves, the compressed air travels along the cham-
ber (8) to the exhaust ports (5), through which it is exhausted into the atmosphere.
Ta.ble 8
Types of Electric Hand Drills and Their Characteristics
b)
C)
d)
.f) i
VD :.5
15
1200
220
4,9
4111;14sA
\
or 120
1
.1 - 111 Aaga.
F0 -8
411"1"1
8
2200 -
220
2.8
47,
or, 120
_Kt_gliiirl-g
FD .9
6
3600220
1.5
'..li77-1t
or 120
a) Type of-hand drill; b) Sketch; c) Maximum diameter of hole, in mm; d) Num-
ber of revolutions per minute in idle running, in rpm; e) Current voltage, in 1
volts; f) Weight in kg
STAT
At an air pressure of 5 atm and higher the motor starts up readily. At some-
55
I
nna-Inecifiarl in Part - Sanitized Copy Approved for Release 2013/04/12 : CIA-RDP81-01043R001900110002-3
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what lower pressures, the drill can be started only by depressing the lever of the
cock to admit air and manually turn the motor by means of the chuck, af:er which the
motor quickly reaches its speed.
At normal pressure of the compressed air in the system (5 atm), the rotor of
the drill develops 12,000 rpm, which is reduced to 2500 rpm by means of the reduc-
tion gear. (11).
In many cases, in place of, or in addition to pneumatic hand drills, electric
hand drills are employed. The technical Characteristics of electric hand drills are
given in Table 8.
An important characteristic of electric hand drills is that they may be used on
jobs and in places where compressed air installations are not available, due to the
lack of air compressor and related equipment.
Figure 53 shows the construction of the electric hand drill FD-8. _The ila.nd
drill is equipped with a universal motor that has a commutator, which may be oper-
ated on either alternating or direct current as available in the power line. The
body of the hand drill consists of three main parts: the upper cover (7), body part
(5), and the lower part (4). Two electromagnetic poles are pressed in the body. The
armature of the motor revolves on two ball bearings. The rotary motion is trans-
mitted from the armature shaft to the drill, which is held in a chuck, through the
reduction gear (2) which ,consists of two gears. The spindle (3) also revolves in
two ball bearings. For the purpose of cooling the windings of the motor, a blower
is mounted on-the motor shaft which sucks in 'air throtigh the ports in the body of
the drill.
Electric current is supplied to the motor through the rubber-insulated three-
wire cable (8). Two of the wires are live, carrying current to the' motor, while the
third is for grounding the drill while in operation.
The choice of the kind of drill used depends on the diameter of the hole, the
nature of the material being worked, and the-accessibility of the work.
56
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STAT
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(f.;
Fig.52 - Pneumatic Hand Drill of Type D-2
a) Vanes are shown in their normal position; b) Cross-section through EE; c) Cross-
section through AB
1 - Air plug; 2 - Valve; 3 - Valve lever handle; 4 - Drill handle; 5 - Exhaust open- ,
incs; 6 - Rotor; 7 - Vanes;
C - Air chamber; 9 - Air channels; 10 - Stator; 11 - Gear
reducer
IJ 5
?.----/mmwomowowNvmwm6w-
peel
" ? ?4 ' 0 -,e. iiililiiiI0
P V,:!I -,
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VI ? = , r
'? r?t a---19" I
it-- \-_, _ p7misim._.eimi.: (sfe,,1
1 ,
7
Fia.53 - Electric :land Drill FD-8
1 - Armature; 2 - Gear reducer; 3 - Spindle; h - Lower
cap; 5 - Body; 6 - Electromagnetic poles; 7 - Top cover;
57
STAT
8 - 3-wire electi-ic cao.Le
-
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-
Lt.*
_
The range of work that may be done with electric hand drills can be increased
considerably by using specialized tools and fittings in the form of extension coup-
lings, angular fittings, and jig bushings which are attached to the body of the hand
? ? so
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' 14,440 :e4tV.
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Fig.54 - Extension Fitting of Type SNP-4, Attached to Band Drill
1 - Lock nut; i - Drill; 3 - Bushing; 4 - Shaft; 5 - Clutch
drill. Extension and angular types of fittings are used for drilling holes in places
which cannot be reached with ordinary pneumatic or electric hand drills, such as
when far-removed or obstructed holes.
Fig.55 - Angular Type Extension Fitting, SNU-5, Attached to Hand Drill
Figure 54 shows an extension fitting of the type SNP-4, attached to the hand
drill. The body of the fitting is rigidlY attached to the front part of the hand
drill. A coupling is screwed on the spindle. The rotation of the spindle is trans-
mitted to the shaft (4) over the coupling (5). The end of the extended shaft car-
ries the bushing (3), which corresponds to the diameter of the drill used. -
For drilling holes in places located close to vertical obstructions, fittings
of the angular extension type are used with the drill. Figure 55 s::ows an angular
STAT
extension fitting of the type SNU-5 for drilling holes at a corner angle of 90?.
58
1
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Fittings of the type SNU-5 are also available for drilling at angles of 450.
The design of angular fittings is similar to that of the extension type, with the
only difference that the rotation of the drill
point at an angle is transmitted from the shaft
over a pair of conical gears or over a universal
joint.
For drilling duralumin, and using simpli-
fied patterns made from thin sheet steel which
are not provided with inserted guide bushings,
Fig.56 - Guiding Device of Type
use is made of guide bushings attached to the
body of the drill tool. One of such attachments
of the type KN-1 is shown in Figs.56 and 57. The housing of this device (5) is put
on the cylindrical part of the hand drill, and has an adapter (4) at its lower end,
in vich the cylinder (3) is held. Inside
this cylinder is the guide bushing (2), held
in its extended position by the coiled spring
(1), so that the drill point is flush with
the bushing. During the drilling operation
the guide bUshing must be inserted in the
holes of the pattern or template, making sure
that the position of the drill is in the
correct position with respect tO the surface
being drilled; then, the power is turned on,
and drilling is started by applying pressure
on the tool. This compresses the spring,
causing the drill point to go through the
guide bushing and properly drilling the hole.
KN-11 Attached on Hand Drill
Fig.57 - Construction of the Guide
1 - Spring; 2 - Guide bushing; 3 - Cyl-
inder; 4 - Adapter; 5 - Housing STAT
.1
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5. Operation of Drill Presses and Rand Drills
The accuracy with which holes are drilled for riveting has an effective influ-
ence on the quality of the work done on the joined seam as a whole. The following
basic factors influence t:.e quality of drill work:
1) Quality of grinding of C'e drill point;
2) Pressure exerted in the drill feed;
3) Diameter and length of the drill;
4) Wobble of the spindle of the drilling tool;
5) Wobble of the chuck;
6) Wobble of the drill in the chuck;
7) Available facilities and skill of the drillers.
The center line of drilled holes must be perpendicular to the plane of the part
worked. To meet this requirement in stacked parts which have a total thickness of
more than 3 mm, special attachments are used on the hand drill (Fig.58).
The attachment device consists of the body (2) which is fitted to the cylindri-
cal portion of the hand drill and made fast with the screw (1). The support bushing
(5) is fitted to the body of the device and is held in its normal position by the
tension of the spring (3). Rubber strips.(6) are cemented to the legs of the bush-
ing in order to protect the surface,Of the parts drilled. When force is applied to
the drill tool, the spring is compressed and the body of the device slides over the
guide bushing with the result that the drill point comes in contact with the surface
of the part worked and the hole is drilled.
. The procedure in drilling holes with a similar attachment is illustrated in
Fig. 59.
The operation of pneumatic and electric hand drills requires much attention and
skill. Before starting the work, the parts to be drilled must be checked for proper
fastening. The part being drilled must be held tight in the assembly fixture or on
the bench. Then the drill is inserted in the chuck up to about 3/4 of the shank STAT
Go
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length, and is tightened by means of a wrench (Fig.60)'. .To verify how well the drill
is held in the chuck, it is tested for wobble at slow speeds by locking and unlocking
the drill in the chuck several times. The causes of wobble and remedies are shown
in Table 9.
Table 9
Causes of Drill Wobble and Remedies
Cause of wobble
_.
Means of eliminating wObble
Drill is crooked
-
Change the drill
Burrs and nicks on the shank
of the drill
Change the drill
Worn out jaws in chuck
_
Change the chuck _
Spindle of drill is tapered
(causing the chuck to wobble)
Replace hand drill
Improper position of drill in
the chuck
Loosen the jaws in the chuck, turn
the drill, and lock it again in place
Having checked and eliminated drill wobbling, the power is turned on, and the
drill is aligned at right angles to the surface of the part worked. At the start of
?
drilling, the operator places his left hand on the body of the hand drill as a sup-
port and bends the index finger of this hand around the drill. The drill point is
thus properly directed,to the center of the hole, which also helps in determining
the required depth 'of the hole (Fig.61).
When holes are drilled in thin sheet plankings, a wooden support must be placed
at the outlet side,of the drill, which protects the sheet from sagging and buckling;
while at the same time protecting the hands of the driller's helper from inj
the drill
? ?
int.
61'
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2
tit
(.4
?
Fig.58 - Attachment on Hand Drill
to Ensure Perpendicularity of the
Holes
1,4 - Screws; 2 - Body; 3 - Spring;
5 - Support bushing; 6 - Rubber
62
?
fib ? ?
lel "41 p.
I
Fig. 59 - Drilling Holes with an Attach-
ment Device to Ensure Perpendicularity
to the Surface of the Part Drilled
Fig.60 - Tightening of tjle, Drill
? 11 STAT
in the Chuck
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f
When drill presses are used, it is advisable to start 'up the press before in-
serting the part to be drilled. Setting the drdll point on the workpiece must be
done careful17, without abrupt jerks or sudden impact, to prevent chipping of tie
drill point which would ruin the surface finish of the raterial. When the hole is
about finis' ed, it is advisable to reduce the feed. If the feed is not reduced, the
drill has a tendency to grip a chip of sufficient size to develop burrs in the metal,
and in some cases also to cause breakage of the drill.
,Ihen drilling deep holes it is advisable from time to time to remove the drill
from the role, without stopping either the drill press or the hand drill, the object
being to remove the accumulated chips. Stopping
the drill press or the hand drill mile the
drill point is still in the hole causes seizing
of the drill in the workpiece and breakage of
,1 Fig.61 - Position of the Hand While
AL'
^
Drilling
the drill.
When drilling deep holes in steel parts a
cooling fluid must be used, which serves at the
same time as a lubricant and a rust preventive.
Table 10 gives suggestions for cooling and lubricating fluids for us in drilling
steel, cast iron, and bronze.
Table 10
Coolants and Lubricants Used in Drilling
,..,_
Materials Drilled
'Recommended- Fluid
,
Carbon steel, alloy steel, tool
steel, and cast steel
Emulsion
Cast iron, bronze
Kerosene; mixture of borax and
water with glycerol
-
AT
In drilling holes into stacks consisting of a combination of steel and duralumin
63
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the drilling should be started from the side of the steel part. In cases when the
hole in one part has to serve as a guide for the hole in the other part, the guide
Fig.62 - Drilling 'Ioles in Steel Tubes with a Pneumatic Hand Drill
Equipped with a Kechanical Feed of the Drill Point
holes should be drilled in the part made of the tougher material. If the material of
both parts is the same, the guide holes should be drilled in the part with the great-
est thickness.
For drilling holes of comparatively large
diameter (up to 32 mm) in steel parts, heavy-
duty hand drills are used which are equipped
with a mechanical feed mechanism, an example of
which is shown in Fig.62. The pneumatic hand
drill shown designed by N.F.Yegorov, has a
Fig.63 - Device for Using Three
Drills Simultaneously for Drill-
ing Holes in Components and Pan-
power rating of 1.4 hp, weighs 4.6 kg, and per-
mits a spindle speed adjustment in the range of
600 to 180 rpm, which is quite important ,when
drilling in metals of various degrees of STAT-
els of Great Length
ness. The availability of a mechanical feed
? 64 i
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I (CI
ce
_
permits shifting the drill smoothly and evenly from one place to another and removing
the drill from the workpiece quickly after the hole is drilled. The clamp which
serves as a support for the hand drill and to absorb the thrust of the mechanical
feed, also absorbs the torsional moment which always develops on the spindle when a
drill tool is in operation, since the body of the hand tool is clamped to the part
drilled.
The rate of production in the assembly sections of a plant can be increased
56
11
A.)
s.
44i. low
-
- A Two-Spindle Attachment
a) View of the reduction gear, with cover plate removed
1 - Pneumatic hand drill; 2 - Chuck; 3 - Oil cup; 4 - Body of attachment;
- Drill point; 6 - Holding pin; 7 - Driven shaft; 8 - Collar; 9 - Drive
gear; 10 - Intermediate idling gear; 11 - Working gears
considerably by using mechanical contrivances to allow simultaneous use of several ?
hand drills. .
Figure 63 shows a device for the installation of three hand drills, for ussTAT
drilling holes into longerons and panels of large length. When combined with means
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rIk.?
?
of support and with provisions for shifting the drills from one place to another, the
use of such a device results in a considerable increase of production and more effi-
cient utilization of labor. All three drills are started at the same time by open-
ing a valve connected with the compressed-air main line. A foot paddle is provided
for feeding the drill points into the work-piece.
Another means of increasing labor output when working with hand drills is to use
multispindle attachments fastened to the body of the hand drill.
The attachment shown in Fig.64 is used for simultaneous drilling of two rivet
.oles and for holding parts together during assembly by means of bolts and wing nuts.
This attachment is mounted to the body of the 'rand drill (1) by means of the collar
(8) and the driven shaft (7) which is locked in the chuck (2) of the hand drill.
The gear (9) is attached to the shaft (7), and rotation is transmitted to the work-
ing gears (11) over the intermediate gear (10). Lubrication of the gears is effected
through oil cups (3). The adoption of this attachment facilitates putting the wing
nuts on the bolts, as well as slipping the nuts over the extension pin (6).
66
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C.&
CHAPTER V
FORMATION OF RECESSES UNDER THE HEADS OF FLUSH RIVETS
1. Means for Forming Recesses
The formation of recesses under the heads of rivets for flush riveting is done
1
by countersinking and dimpling.
Countei.sinking is done when the thickness Si of the exterior part, such as the
skin, is equal or more than the height h of the inserted head of the rivet (Fig.65a).
If, however, the thickness 61 of the planking is less than the height h of the in-
serted rivet head, and the total thickness of the stack of joined pieces S is not
greater than the diameter of the rivet, dimpling is used (Fig.65b).
ecis
N
JobS
e
a)
1
Fig.65 - Methods of Forming Recesses
a - Countersinking; b - Dimpling; c - Countersinking and dimpling
Countersinking of the inner part, such as the airframe, and stamping of the
outer part, such as the skin or planking, is done whenever the thickness 62 of the
airframe does not permit a dimpling operation and when the thickness 61 of the
planking is less than the height of the head of the inserted rivet (Fig.65c). STAT
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2. Countersinking
The quality of the work in flush-riveting depends basically on the geometric
correspondence of the contour of the rivet head with the contour of the recess. Con-
sequently, the operation of countersinking is one of the most important processes in
the art of flush-riveting. The accuracy with which this is done influences the de-
gree of smoothness of the surfaces and the strength of the flush-riveted joint.
The quality of countersinking work depends basically on the following factors:
1. Design and geometry of the cutting edge of the countersink;
2. Design of the countersink attachment;
3. Wobble of the countersink and the pilot pin;
L. Dimensions of the drilled hole;
5. Skill of the operator.
Countersinking is done by two methods: simultaneously with or independently of
drilling.
Countersinking while drilling may be done
by laying-out with a pencil, by laying-out and
center-punching, and by using guide holes
(Fig.66). Drilling and countersinking in the
same operation, according to guide holes, re-
sult in a considerable reduction of labor, in
Fig,66 - Methods of Countersinking
a - Countersinking done simultane-
ously with drilling on layout;
b - Countersinking done simultane-
ouSly with drilling through guide
holes; c - Countersinking of a
pre-drilled hole with a pilot
point
bination of drill4and.countersink or
an increase in production, and in an improve-
ment in the quality of the work done.
Countersinking Tools and Attachments. Tools
with pilot stems are used for countersinking
holes which have been previously drilled
(Fig,67a). Such tools may be an integral com-
a countersink attachment on the drill. The
STAT1
of a countersink attachment on the drill (Fig.67b) appears to be more rational than
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the use of a combination drill and countersink.tool, since in the first instance, if
the drill breaks, which is usually more frequent than breakage of the countersink,
the drill may be changed and the work continued with the same countersink.
In selecting a countersink, the di-
mensions and type of rivets used on any
one job should be taken into consideration,
along with the material of the part on
which work is done. Countersinking tools
must have a diameter somewhat larger than
the diameter Of the rivet heads.
Countersinks with three cutting edges
a)
are used for making recesses in duralumin
Fig.67 - Shapes of Countersinks
and in steel, while countersinks with only
a - Countersink with a pilot stem;
two cutting edges are used for parts made
b - Drill with countersink attachment
of magnesium alloys.
The cutting edges of the countersinks must be ground to a sharp edge and the
grooves must be polished. When working with dull cutting edges the surface of the
recess becomes filled with metal filings, while
the .cut chips of metal adhere to the working sur-
faces of the countersink, thus interfering with
proper performance of the operation. Grinding of
the cutting edge of countersinks is done in cen-
tralized workshops.
Wobbling Of the working part of the counter-
sink should not exceed 0.02-0.03 mm to prevent
wrong dimensioning of-the diameter of the recess.
The amount of wobble in a countersink is determined by an indicating device,
the tip of which is brought in contact with the surface of the driven shaft oiSTAT
Fig.68 - Schematic Diagram for
Checking a Countersink with 'a
Wobble Indicator
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_
y
countersink (Fig.68).
Adjustable attachments on the body of pneumatic hand drills or on countersinking
and drilling presses are used for determining the correct depth of the recess to
match the shape of the specified rivet head.
Countersinking attachments must meet the following basic requirements:
1) The wobble of the countersink, when installed in the attachment device, mist
not exceed 0.02-0.03 mm;
2) The attachments must be provided with adjustable supports for regulating the
depth of the recesses with an accuracy up to 0.02 mm;
3) The attachments must have an accessory mechanism for the disposal of chips
while it is in operation, and the thrust support which comes in contact with the work
must not damage the surface of the part worked;
4.) The attachments should be of relatively small size and weight;
5) The thrust support should be of such construction that it will not obstruct
the visual range of the recess;
6) After the attachment is installed and adjusted for the depth of the recess,
it must be able to make a recess that will be properly filled by the rivet head;
7) The body of the attachment must be permanently and tightly attached either
to the body of the hand drill or the countersinking and drilling press.;
Various types of countersink attachments are used for riveting of light alloy
structures, and these may be grouped as follows according to their design and appli-
cation:
a) Attachments fastened on hand drills or drill and countersink presses pro-
vided with chip-discharge means;
b) Attachments fastened to the body of hand drills and presses without a
blower for chip discharge;
c) Attachments fastened to the chuck of the hand drill or press;
d) Attachments fastened to the spindle or*shank of the drill in hand drills
STAT
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or drill and countersink presses.
The type ZN-2 attachment (Fig.69) ensure accuracy of depth of the recess to
+0.03 mm. The body of the attachment (1) is slipped ovel:- the cylindrical part of the
hand drill D-2, and the spindle of the attach-
ment thus becomes fitted to the spindle of the
hand drill. Rotation of the countersink (6) is
transmitted from the drive shaft (4) over the
tapered bushing (7). The depth of the recess
is limited by the thrust support (5), which is
shown together with the spring (9) in the ex-
tended position. The adjustment for the speci-
fied depth of countersinking is effected by the
sleeve (3), which is regulated and held in place
by the screw (10). After adjusting for the re-
quired depth setting, the ring (2) is fitted and
permanently sealed in position with the seal
(13).
Fig.69 - Countersink Attachment
of Type ZN-2
a) Cross-section through AA
1 - Body; 2 - Ring; 3 - Bushing;
4)- Drive shaft; 5 Thrust sup-
port; 6 - Countersink; 7 - Bush-
ing; 8 - Grooves; 9 - Spring;
10 - Screw; 11 - Tubing; 12 - Hol-
low collar; 13 - Seal
The surface of the thrust support is
chromium-plated and polished in order to protect'
the surfaces of the parts being countersunk from
damAge. A hollow collar (12), together with
rubber tubing and packing is provided for the
removal of the chips formed in the countersink-
ing operation. In operation of the hand drill,
the exhausted air from the blower in the drill
goes from the exhaust ports into the hollow '
collar (12), into the tubing (11), from which ,
STAT
the air current is directed to the space Len
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? .????.
the body of the attachment and the thrust, and thence through the grooves (8) into
the hole being
The loose
countersunk, thus blowing away the chips.
coupling of the drive eliminates the possibility of transmitting any
wobble of the hand drill spindle to the counter-
sink.
Fig.70 - Countersinking Attach-
ment of Type ZN-1
1 - Pneumatic hand drill; 2 - Body
of attachment; 3 - Screw for
mounting the ,attachment to the
hand drill; 4 - Spindle; 5 - In-
terchangeable'countersink;
.6 - Tripod; 7 - Adjustable prop;
8 - Ball rest of fabric laminate
to prevent damage to the surface
of the workpiece
Figure 70 shows a countersinking attachment
of the type ZN-1. The body of the attachment
(2) is fitted to the hand drill, while the spin-
dle (0 is mounted to the tapered spindle of the
hand drill. The threaded end of the body car-
ries the thrust support (7) with its locknut,
for adjusting the depth of the recess. The body
is slipped into a tripod (6), with the three
equidistant screwed-in legs at the same distance
from the center.
The tripod is used for aligning the hand
drill with the attachment perpendicularly to the
surface of the part, Bakelite or similar lam
inated balls (8) are fitted into the ends of
the legs to prevent damage to the plated sur-
face. The attachment is supported on the tripod
by means of a spring, shown in its extended
position.
The use of this attachment has certain
drawbacks. The countersink is rigidly connec-
ted with the spindle of the hand drill over the
reducing bushing and thus is subject to any wobble of the drill spindle. Also the
absence of an air blower in this device causes the chips to fall in the space 111-Wren
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ra-p-1
t
1 1
the panels being dimpled. An obvious advantage of this device is its simplicity of
design and its correct position with respect to the outer surface of the lining or
other part being worked.
Fig.71 - Countersinking At-
tachment Inserted in the
Chuck of a Hand Drill or Drill
1 - Countersink with pilot
stem; 2 - Bushing; 3 - Spring;
4 - Thrust ball bearings;
5 - Support nut; 6 - Lock nut
Figure 71 shows an attachment mounted to the
chuck of a hand drill or of a drill and countersink-
ing press. It consists of the countersink (1) with
a pilot stem. The bushing (2) is fitted to the
countersink over the thrust ball bearing (4). The
spring (3) is within the bushing (2). The lock nut
(6) is used for fixing the countersink in its ad-
justed position. Regulation of the depth of the
recess is obtained by screwing in the countersink
or screwing out the support nut (5).
Countersinking with the aid of this attachment
is performed in the following manner; After adjust-
ing the device for the specified depth of the recess,
the shank of the countersink is inserted in the
hand-drill chuck, and the power is turned on. The 1
hand drill is, held in the right hand while the bush-
ing is held in the left hand with which the pilot
stem of the countersink is inserted into the drilled
hole. As pressure is applied on the hand drill the hole is countersunk to specifi-
cations.
This attachment is simple in construction but, at the same time, is not a
sensitive device; for this reason, its use is limited to countersinking in parts for
which a high degree of surface smoothness is not required. Since this attachment is
inserted directly into the chuck of the hand drill or drill press, it is obvious
that any wobble will be transmitted to the countersink. The body of the attachment
STAT
73
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1.4
Ara.7.7.?,,zr
must be held by hand while in operation to prevent'the support from scratching the
surface of the part worked. The advantage of this device is its light weight and
small size, which *facilitates the work.
Figure 72 shows an attachment mounted directly to the spindle of a hand drill
or a drill-countersink press (countersink chuck). This device permits an accuracy
of ?0.04 mm, and its small size and weight contribute to better utilization of labor.
Of all described countersinking attachments
used for flush-riveting work, preference should
be given to the types ZN-2 and ZN-1, which give
greater accuracy of work. These attachments are
for use in places where a high degree of smooth-
ness of the riveted joint is necessary (wings,
center sections, etc.). IA spots where the
technical spebifications do not require a high
degree of smoothness, it is rational to use the
attachments shown in Figs .71 and 72.
As already stated, before countersinking is
started, the attachments used should be adjusted
for the specified depth of the recess and flied
Fig.72 - Countersinking Attach-
ment Nbunted Directly to the
Spindle of Hand Drills or Drill
Presses (Countersinking Chuck)
in that position
to prevent misalignment.
The adjusting of the attachments is done by mounting on a test rig with cali-
brated recesses, and is further checked by countersinking not less than five holes
in specimens which must be the same as the material of the parts to be countersunk.
The mounting on the test rig is carried out in the following sequence
(cf. Fig.73):
1,) Place the support of the attachment so that the countersink fits the cali-
brated recesses, which are of dimensions corresponding to the minimum dimensions of
the heads of the rivets to be used (Fig.73a);
74.
STAT:
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I.
"?-?
2) Countersink not less than five recesses in specimens (Fig.73b);
3) Measure the depth of the recess with a calibrated rivet and an indicating
instrument. (Complete data on the dimensions of calibrated rivets are given in
Table 11). .
In case inaccuracies of the setting are revealed, the necessary corrections in
the setup are made, followed by repeat countersinking tests and measurements of the
recess dimensions. The setting .of a countersinking attachment is considered correct
only if, after inserting the calibrated rivets into the recessed holes, the rivet
heads protrude by not more than the minimum height permitted by the design specifi-
cations for the finished structure.
Cf
Fig.73 - Sequence for Adjustingend Checking Countersinking Attachments
a - Position of support in a calibrated recess; b - Sample of countersinking
of not less than five holes; c - Checking the depth of the recess
When the countersinking attachments are fully tested; they must be sealed with
lead seals. Only sealed attachments may be issued to the workmen.
It is forbidden to work with attachments with broken seals (since this indicates
tampering with the setting) which may lead to imperfect countersinking (that is, ex-
cess or inadequate countersinking of the recesses).
Depth of Countersinking. The depth of the
face quality of the work done in flush-riveting
sinking leads to protrusion of the rivet heads,
0
recesses greatly influences the sur-
of joints. Insufficient counter-
while excessive countersinking re-
Investigations haSTATve
sults in a depression of the rivet heads below the surface.
75
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CD
0
(D
h:
CD
CD
CD
0
0
CN
-
.-,,t,vctleir=
01'57
,
-t
Table 11
Dimensions of Calibrated Rivets in mm
a)
ce
90?+ 10
1200+ 10
b)
. a
4
h
d
D
h
c)
d)
c)
d)
c)
d)
c)
d)
c)
d)
c)
d)
? ?
F.tIrt
2,6 ,
3
3,5
4
2,6
3
3,5
4
.
-
.
:4,6,_
5,2
6,1
i
1,1
1,2'
1,4.
1,6
,
2,6
3
3,5
4
5,35
6,10
6,90
7,80
0,9
1,0
1,1
1,2
11
'1,
5
6
.8
9,5
10
5
6
8
9,5
10
-I 0,02
.
?
8,8
,19,6
1'4,2
16,8
17,7
-0,05
'
,
2
2,4
3,2
3,8
4
'- 0,01
5
6
-
-
-
+0,02
-
9.5?
11,50
-
-
-
-0,05
1,4
1,7
_
-
-
?
-0,01
Notes: 1 - The material for the rivets is a brand of steel of the type U-12-11.
._
0.) 2 - Heat treatment: quenching and annealing Rc = 56-64.
H
>
--I' a) Sketch;. b) Diameter of rivet; c) Minimum dimension; d) Tolerance; e) Nominal dimension
0
CD
0
CD
-o
n-
(/)
CD
0
CD
CD
7:1
(T)
CD
0
CA)
0
Declassified in Part - Sanitized Copy Approved for Release 2013/04/12 : CIA-RDP81-01043R001900110002-3
("-
shown that these defects are due principally to a variation in fit or the noncoinci-
.
dence of the rivet heads withthe recesses.
The curve slope (Fig.74) indicates that, if the holes are not sufficiently
countersunk, i.e., if the height of the rivet head is more than the depth of the
recess, then the left part of the experimental curve approaches the theoretical
curve. The observed discrepancy between the experimental and theoretical curves is
explained by the fact that, after the riveting is completed, the rivet head becomes
upset under the pressure, but still protrudes over the surface of the planking.
Q3
?
?
\
. 7f 1
2
I
1-1
.11 .
0.
se
if
?
\
- ? b)
1 l i I I
0.1
\
0,3
0,2
e)
0.1
-til -0.2
5)
- 0.3-
- Correlation of Protrusion of Rivet Heads and Depth of Countersunk Recess
a) Theoretical curve; b) Experimental curve; c) Protrusion of the rivet head, Ah;
d) Depression of the rivet head; e) Difference between height of rivet head and
depth of countersink recess (h1 - h2), in mm; f) Difference between depth of recess
and height of rivet head (h2 - h1), in mm
The opposite characteristic of the curve segments occurs when the depth of the
recess is greater than the height of the rivet heads, i.e., when the recess is ex-
cessively countersunk. In such cases, the experimental curve deviatesfrom
- STAT
77
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1 ?
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the theoretical curve. This is explained by the fact that, in the process of rivet-
ing, the rivet head abuts the flat surface of the set die so that, after riveting,
the top of the rivet head is only sliertly below the surface of the planking, while
in some cases it is either flush with the surface or protrudes slightly.
In cases where the depth of the recess is significantly greater than the height
of the rivet head, (e.g., over 0.1 mm), the rivet head does not fill the recess ade-
quately, leaving a clearance between the surface of the recess and the rivet head
(Fig.75). This reduces the strength of the joint when subjected to stresses and .
lowers the corrosion resistance of the seam.
The strength .of flush-riveted joints with various depths of countersunk recesses
was investigated on specimens in shear and tensile test with static, vibration, and
repeated static loading.
Table 12 and Fig.76 show that, in shear with static loading, the strength of
the joint increases as the depth of the repess is increased. This is due to the fact
that the cross-sectional area under shear is increased because of the conical shape
of the rivet head which penetrates into the mating sheet. Macrographs of the speci-
mens are shown in Fis.75.
Another characteristic of the curve in the graph is shown in that portion of it
where the depth of the recess is less than the height of the rivet head, that is,
when the countersinking is insufficient. In such cases, since the stem of the rivet
is of uniform area in shear, the failure load or the ultimate strength is nearly
constant, regardless of the depth of the countersunk recess. This is shown in
Table 12.
Tension tests with static loads on specimens, as shown in Table 13 and Fig.??,
have demonstrated that as the depth of the recesses is increased, the strength of
the joint is lowered. The reduction in the strength of the joint, corresponding to
the increase in the depth of-the recess, is due to the fact that the area of intimate
contact of the conical surface of the rivet with the material of the rivetedSTAT:, is
78
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I N -
?
Table. 12
Strength of Joints in Shear as a Function of Depth of the Countersunk Recess
a)
b)
bV=1,5 min
22,0 mm
1 rnni
c )
mutat,
\ his
Iin Keinnnt
in % ppilcors .
in Kt,
d)
0,3
0,2
0,1
1815- 20,6 93 1960
1815 20,6 93 1937
1900 21,6 97 1947
0
1958 22,3 100 1860
f
0,1
0,15
0,2
0,3
1583 22,5 101 1832
2010 22,9 103
2226 25,3 114 1885
2291 26,1 117 1830
T ? ultimate shear strength of rivets
1.?
retI
c1/4
22,3_
105,3
22,0
104,0
22,1
104,6
21,1 100
20,8
98
21,4
101
20,8
98
a) Deviation of depth of recess from normal, in mm; b) Characteristics of joint;
c) Strength; d) Depth of recess 19ps than normal by; e) Recesses made to normal di?
mensions; f) Depth of recesses greater than normal by
79
STAT
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?
less.
It should be noted that seams in which the rivet heads protrude above the sur-..
face of the planking are deformed less when subjected to static loads (Fig.76).
'?
Fig.75 - Eacrograph of Specimens Used for Investigating the Effect of Recess
Depth on the Quality of Riveted Joints
1 - Depth of recess less than normal dimensions by 0.1 mm
2 -
same by 0.2 mM
3 - same by 0.3 mm
4 - Countersunk recess made to normal dimensions
5 - Depth of recess greater than'. normal dimensions by 0.1 mm
6 - same by 0.15 nml
7 - same by 0.2 _mm
8- same by 0.3 mm
a) Depth of recess less than height of rivet head; b) Depth of recess equal to
height of rivet head; t) Depth of recess greater than height of rivet htiAT
80
"
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? ,t.*
VI'Mlata" -
:1
1
a
-
of
, :For example, on stressing the seam to a tension of o* = 6 kg/mm2, the slip which
takes place in the parts joined, as a function of the depth of the countersunk re-
cess, is as follows:
a) 1.3% of the diameter of the rivets, in seams where the depth of the recess
is less than the height of the rivet heads;
b) 2.1% of the diameter of the rivets, in seams where the depth of the recess
is the same as the height of the rivet heads;
c) 4.4% of the diameter of the rivets, in seams where the depth of the recess
is greater by 0.2 mm than the height of the rivet heads;
d) 15% of the diameter of the rivets, in seams where the recess is greater by
0.3 mm than the height of the rivet heads.
The results of the vibration tests, as given in Table 14, show that joints in
which the countersunk.recesses were made smaller than the specified normal dimen-
sions, have a higher fatigue strength under all test conditions. On the other hand,
joints in which the recesses were made'-larger than the required normal dimensions,
have a lower fatigue strength under all test conditions. However, where the recesses
are either over-countersunk or under-countersunk by 0.1 mm,- and also in joints where
the depth of the recesses is the same as the height of the rivet heads (since here
the recesses were made to the specified dimensions), the fatigue limit remains con-
stant at the value of unit stress o = 4.7 kg/mm2. Compared with the case when the
recesses are made to specified dimensions, joints made with over-countersunk recesses
by 0.2 mm, have their strength lowered by 4%, while the strength of joints in which
the recesses are under-countersunk by 0.2 mm, is higher by 10%.
This may be explained by the fact that the rupture of the plates under Nibra-
tion loads takes place in the weakened cross section of the specimens along the first
'The tensile stress cy was determined as the ratio of total load applied at the joint
to the area F of the entire cross section of the specimen sheets tested.
81
STAT
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11-%1
-
Table 13
Strength of Joints in Tension as a Function of Depth of Countersinking
120
?1 76u-
a)
5)
q)
11)
b)
wirn
B2=2,0 mmn
Bi=b2=2nlm
c)
d)
e)
in 94
d)
e)
In
0,3
1368
18,2
112
1970
26,1
110,6
0,2
1330
17,6
109
1900
25,2
106,8
0,1
1280
17,0
105
1820
24,1
102,1
1223
16,2
.100
1780
:23,6
100
0,1
1166
15,4
95
1755
23,2
98,3 s
0,15
1140
15,1
93
6,2
1080
14,3
88
1740
21,8
92,3
0,3
1033
14,3
88
1660
22
93,2
a) Amount of deviation of the depth of the recess from:normal, in mm;
b) Characteristics of the joint; c) Strength; d) Pf-ailure in kg; e) in
kg/mm2; f) Depth of recess less than normal by; g) Recesses made to normal
dimensions; h) Depth of recess greater than normal by; i) o = ultimate ten?
STAT
sue strength of the riveted joint with the rivets in tension
82
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(D
Oh
(D
(T)
(D
n.)
0
n.)
0
-o
co
0
0
0
:0
0
k.t3
...
i
I
12,5 15
g5
??
115
c>?
1
; ,,,,?14
a)
105
4 ?i
.......
?Al
WO
...
J4-310-4
li
.
.9
40
111P 4 ?
/
-
i 111 i
?...."....1
,..
_
L.....I
'6
E i
ft I
?
c)
?
Fig.76 - Effect of Depth of Countersunk Recess on Strength of the Joint. Thickness d, of the Counter-
sunk Plate Less than Height h of the Inserted Rivet Head (The Rivets in the Joint are Subjected to
Shearing Action)
c.f)
>
Hai Strength in %; b) Rating; c) Depth of recess greater than specified normal; d) Depth of recess
less than specified normal
(D
0
(D
-0
n-
(D
0
(D
1:31h
7:1
(D
(T)
(D
0
0.)
0
. .
0
7:1
-0
CO
0
0)
0
0
co
0
0
0
0
0
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?. it
120
115
1
110
10S
f20
u,
..),
111111111
t
111111111
1. ?
r
gaillEgV
I
-
-
mrti 003
C,2 0/
0,1
d)
mm
Fig.77 ? Effect of Depth of Countersunk Recesses on Strength of the Joint with
the Rivets Subjected to Stress in Tension, and with the Height of the Rivet
Heads Greater than the Thickness El of the Upper Plate
a) Strength in %; b) Rating; c) Depth of recess greater than specified normal;
d). Depth of
6K9finni2/4 ts,
13
12 ?
/f
10
9
8
7
4
3
2
recess less than specified normal
??.
ZS 5 75 10 12.5(5 17420 22,5 25 2Z5 30 32 5 35- 37.5
Slip or dispLacementof plates td);n% of diameter of rivets
(d)
Fig:78 ? Deformation of the Joint as a Function of the Depth of the Countersunk
Recess Under the Inserted Rivet Heads
a Recess under inserted rivet head, 0.1 mm below specification
Recess under inserted rivet head, 0.2 mm below specification
Recess under inserted rivet head, 0.3 mm below specification
o Recess made to specified normal dimensions
ip Recess under inserted rivet head, 0.2 mm above specification
411. Recess under inserted rivet head, 0.3 mm above specification
o',..2.(F is the area of the entire cross section of the plate)
c?
. 84
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,
?\?4
1.?
STAT
4Allesese,
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4"
Table 14
Strength of Joints with the Rivets under Shearing Stress
(The tests were carried out under conditions of vibration loading)
Deviation of the
depth of recess from
specified normal
Depth of recess
less than spec-
ified normal
Recesses made to
normal specified
dimensions
Depth of recess
greater than
specified normal
in mm
0.2
0.1
0.1
(.2
Fatigue point of the
seam as unit stress
c'w sh , in kg/mm2
5.2
4.7
4.7
L.7
4.5
in %
110
100
1 100
I
100
96
Note: The'vibration tests were made on the basis of 107 cycles.
4147Par
Aohm
6.5
6.0
5.5
5.0
4.5
+tq
3Y-92-4
110 4 10 81 ior z of . toe 07
a). ,
Fig.79 ? Fatigue Strength of the Joint as'a Function of the Depth of' Countersunk
Recess, with the Rivets Subjected to Shear and the Plate to Tension Stresses
- Recess made to specified normal dimensions'
a - Recess made less than normal by 0.1 mm
- Recess made less than normal by 6.2 mm
4 ? Recess made greater than normal by 0.1 mm
? - Recess made greater than normal by 0.2 mm
a) Number of cycles. d = (F is the area of the entire cross-section of the
plate, in mm2) STAT
85
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?
'
.t
row of rivets, along the line of the three holes in the plate 51. Also to the ex-
tent that the depth of the recesses is made greater, the area of contact between the
rivets and the plate in the first row becomes less, which contributes to the lowering
of the fatigue 6trength of the joint.
4
Table 15
Strength of Joints on Tests with Rivets in Tension
Deviation of the
depth of recess from
specified normal
Depth of recess
less than spec-
ified normal
Recesses rade to
, norral specified
dimensions
Depth of recess
greater than
specified normal
in mm
0.2
0.1
0.1
0.2
Fatigue point of the
seam as unit stress
d G) sh) in kg/11.1112
4.5
4.5
4.5
4.5
4.5
in %
100
100
100
100
100
Note: The tests were made on the basis of 5 to 105 vibration cycles.
The indicated results are confirmed by tests with the rivets in tension on
vibrational loads (Table 15 and Fig.80). Under the conditions of these tests, the
strength of the joint decreases at the higher rates of loading as the depth of the
recesses is increased, but the fatigue limit does not change.
In this manner, the tests made in shear and in tension with vibration loads
show that a variation in the depth of the recesses, within the limits of 0.1 mm,
does not affect the fatigue strength of the joint. A deviation from the tolerance
given in the, direction of over-countersinking (+) leads to a lowering of the strength
of riveted joints.
On the basis of the results obtained on the specimens in shear and in tension
under repeated static loads, made with various depth of the recesses, Table 16 shows
that in the ease of testing the specimens in shear, their strength remains stAvt,
86
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?
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Table 16
Humber of Repetitions of Load on Specimens Tested in Shear and in Tension with
Various Depth of Countersunk Recesses
a)
c)
e)
d)
Gum :9,1 KgPilm
a111in=0,91 %Omni,
0,2
i)
? 10117
11872
9580
10529
0,1
g)
h)
0,1
;)
;)
i)
9495
9410
9790
9565
11330
1.0892
11189
11137
Ipoo
12700
11542 ?
formen 13 K
,3 XleilMmnt2
mm
366
349
325
346
431
285
331
349
434
311
380
426
407 '
454
429
0,2
14302
15914
11816
14010
524
438
515
492
a) Deviation of the depth of recess from normal dimensions, in mm; b) Kind of test;
c) Shear; d) Tension; e) Stress in specimens; f) Depth of recess greater .Ehan speci-
fied normal dimensions by mm; g) Depth of recess made to normal dimensions; h) Depth
of recess less than normal dimensions by; i) Average value
STAT
87
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unchanged, regardless of the depth of the recess. Some increase in strength is ob-
served in specimens in which the inserted flush rivet heads protrude above the sur-
face of the plate.
When subjecting the rivets in a joint to a tensile strain, under repeated static
loads, their strength increases to the extent to which the depth of the countersink-
ing of the recesses is reduced.
The following conclusions may be derived from what was stated above:
1. In order to obtain the required degree of surface smOothness and strength in
flush-riveted joints, the shape and dimensions of the recesses must correspond to
the shape and form of the inserted heads of the rivets used in making the joint.
2. Protrusion of the rivet heads in flush-riveting over the surface of the
sheet lining contributes to an increase in strength of the joint under all types of
load application (with static, vibration, and cyclic loads).
3. Joints in which the recess underneath the inserted rivet heads has a depth
exceeding the specified normal dimensions by 0.1 mm and more, have a lower strength
under all types of load. An exception is the case where the thickness of the upper
countersunk plate is less than the inserted rivet heads, when tested in shear on
static loading.
, 4. The deformation of joints in which the inserted heads of the flush-type
rivets protrude above the surface or are flush with the surface, is considerably
less than the deformation which takes place in joints where the inserted rivet heads
are depressed relative to the surface of the planking.
For these reasons, it is necessary in the process of countersinking recesses
to check systematically the quality of the work and the accuracy of the recesses.
In case there Is a deviation from the technical instructions and specifications that
are in effect governing the countersinking of recesses in any given major unit or ?
component, further work should be discontinued until the defects and causes of the
deviation from specifications have been eliminated. STAT
88
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A
?
4CIP
11"\i
4
si7
??- ?
The material from which it is made and the cleanliness of the surface of the
pilot stem of the countersinking tool has a considerable effect on the quality of
the countersunk recesses. Proper quality of work and a reduction in the deviation
Fig.80 - Fatigue Strength of Joints as a Function of the Depth of Countersunk
Recesses (with the Rivets Subjected to Elongation in Tension; Plate Thickness
are 51 = 1.5 mm, 52 = 2.0 mm)
O - Recess made to specified normal
a - Recess made less than specified normal by 0.1 mm
o - Recess made lest than specified normal by 0.2 mm
- Recess made greater than specified normal by 0.1 mm
? - Recess made greater than specified normal by 0.2 mm
(f3 is the area of a cross section of the rivet stem in mm2. n is
nf3
a) 6 max
the number of rivets in the seam).
from correct dimensions is obtained by making the pilot stems from steel tempered
at red heat and well polished, and of the same diameter as that of the drill used
for the hole.
In countersinking recesses, it often becomes necessary for the workman a +he
STAT
inspector to check the depth of the recess. The checking is usually done by visual
89
1
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? .^
.a.
inspection of the fit of the rivet or by using indicating instruments. In such
cases, the inspection of the rivet must be followed by pushing it out from the oppo-
site side, i.e., from the side of the airframe, which involves a loss of production
time since two workmen are needed to perform this operation. At the suggestion of
Engineer M.V.Feofanov, a device known as a vacuum extractor (Fig.81) was adopted at
one of the industrial plants for the purpose of removing the rivet from the side of
the planking after inspection Of the recess. This device
2 consists of a cap (1) which is screwed into the body (2).
The tube (3) is held in the extended position by the coil
spring (4). The screw (7) fits into the lower part of the
tube (3), with its head in the center of the piston (6)
which, on the upper part, carries the washer (5). The pis-
ton fits and slides in the tube (8), which has a rubber
gasket (9) at its lower end.
As shown in Fig.821 this device is used in the follow-
Fig.81 - Vacuum Ex-
ing manner: The vacuum extractor is placed on the surface
tractor for Rivets
of the planking over the place where the fit of the rivet
1 - Cap; 2 - Body;
with the recess is being checked. Pressing down by hand on
3 - Tube; 4 Spring;
the cap (1) causes the movable mechanism to move down;
5 - :lasher; 6 - Piston;
while the air under the piston is expelled through the ,
7 - Screw; 8 - Tube;
clearance between the screw (7) and the piton to the at-
9 - Rubber gasket
mosphere. As shown in Fig.821 after the piston is in its
lowest position and the pressure on the is removed, the action of the spring
rapidly returns the piston to its upper position, while the head of the screw (7)
closes the clearance passage for air, thus creating a vacuum in the chamber under-
neath. Due to the difference in pressure acting on the head of the inserted rivet
and on its stem, the rivet is expelled and is caught inside the chamber of the
STAT
tube (9). A hermetical seal be-areen the planking and the device is provided by the
90
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rubber ring (8).
3. Dimpling
The recesses under heads of flush rivets may also be made by dimpling. Dimpling
can be done individually on each sheet or part of the joint or on two or three parts
a - Vacuum extractor
a)
Fig.82 - Vacuum Extractor
installed on the planking surface, with the movable mechanism
in its extreme low position; b - Instant of eXpulsion of the rivet from the recess
1
%%'S'
Aeodr< ? ? 'ow
,V471!..1 r
. II
?VA
N.N.VOC N.N.N.N.N.,,#,eAele.0117
I
4)
VoWle
Fig.83 - Methods of Dimpling Recesses
a - Dimpling with a punch and die; b - Dimpling with the rivet head
1) Punch; 2) Die
at the same time, depending on their thickness. Multiple dimpling of recesses in a
stack of several parts increases the labor productivity and eliminates the necessity
of spending time in making the recesses coincide during assembly of the parts.
Dimpling of recesses in parts made of alloy V95 is done by preheating the area
STAT
91
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2
j Recesses may be dimpled by two methods, namely: 1) with a punch and die;
.12) using the rivet head itself (Fig.83). Depending on the method used in dimpling
0\
t
in which the recess is made.
1 t'
recesses, the tools used can be classified into the following three groups (Fig.84):
1) Devices working on the principle of crimping the holes;
2) Devices working on the principle of drawing dies;
3) Devices working on the principle of crimping the holes and using a chisel
blade.
Dimpling the recesses with the above devices is done on presses or with pneu-
matically operated hammers.
GJ
a)
- Types of Tools for Dimpling Recesses
a - Tool working on the principle of crimping the holes; b - Tool working on the
principle of drawing dies; c - Tool working on the principle of primping the holes
with use of a chisel blade
Below, the requirements for recesses for flush riveting made on dimpling tools
and machines are given:
1) Preservation of the original aerodynamic smoothness of the surface of the
parts dimpled;
2) Obtaining precise recesses with an even and smooth transition from the
surface of the part worked; STAT
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"
'
"
i
. 3) Absence of cracks and torn edges in the dimpled recesses;
4) Feasibility of dimpling recesses in sheets of various thickness, either
separately or in a stack of two or three at a time.
'411en working with the tools of the first group, as shown in Fig.851 the recesses
are obtained by radial flexure or bending of the material. The effect of the bend-
in E is manifest not only in the area of the recess but also in the adjoining portions
Table 17
Diameter of Drilled ,Eales for Dimpling Recesses with Tools of the First Group
Diameter of rivets, in mm
. 2.6
5.0
4
5.0
Diameter of holes drilled
before dimpling of recesses,
in mm
2.1
2.7
3.6
4.1
of the material, -b.-us producing a cambering of the material.
. ,
In this case, during the first stages of dimpling, the sheet is deformed over a
y
tait
C)
,
Fig.85 - Schematic Diagram of Procedure in Dimpling Recesses with
Tools of the First Group
a - Aligning the part with the pilot stem of the punch; b - Holding the part in
place; c - Initial stage of dimpling by crimping the hole; Last stage of the
dimpling process
STAT
radius larger than the radius of the die. On further application of pressure in
dimpling, the radius becomes smaller, and in the last stage it becomes equal to the
93
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ueclassified in Part - Sanitized Cop
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,
ti
?
radius of the die. On completion of the dimpling, the radial stresses in t e bent
area produce considerable elastic deformation of t..e material in the recess, in-
creasing the angle of the protruding material by 3 to 4? in the area of the recess.
1:ost of the deformation is on the convex side of the recessed hole, which con-
tributes to the development of radial cracks (Fig.86). The presence of cracks a-
round the hole depends also on the quality of the work. Special attention must be
given to the presence of burrs which arc the principal cause of development of
cracks. For this reason, it is necessary to remove all burrs after drilling. The
drilling of the holes must be done from the inside of the
part, i.e., from the side on which C.e protruded portion of
the recess will appear. This precaution results in reduc-
ing the number of burrs at the outlet point of the drill.
Dimpling of recesses with the described tools is done
Fig.86 - Cracks on
by pre-drilling the holes to a diameter corresponding to
the Convex Side of
that of the rivets (Table 17).
the Recess
Work with the tool shown in Fig.85 is done in the fol-
lowing sequence: The tapered pilot stem of the punch is placed into the pre-drilled
hole; from the opposite side, the mating die is placed in position (Fig.85a), after
a)
Fig.87 -'Schematic of the Procedure Used in Dimpling with Tools of the Second Group
a - Placing the part to be stamped over the pilot stem of the punch; b
stage of dimpling (pressing the part tightly against the hole); c - Drawing of the
material; d - Finishing operation of the process
b)
94
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>
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'
ri-t*
?
417L-s,
"
*a*
-
a?-;
dwhich the pneumatic hammer or press is started up. During the first stage of opera-
-
tion, the hammer or the press tool tightly presses on the part being stamped, as
shown in Fig. 85b, and finally the punch is brought into action and the dimpling of
the recess is completed to the required dimensions (see Fig.85c,d).
It is either possible to dimple each part separately or both mating parts to-
gether. It is feasible to dimple the stack of mating parts at the same time, but it
is not recommended to dimple the parts separately, since this will result in a lower
production output and a poorer surface smoothness. In individual dimpling, the parts
ktr.
Fig.88 - Schematic Diagram of Dimpling with Tools Provided with Rubber Sup-
port Sleeves
a - Placing the part to be dimpled over the pilot stem of the punch; b - Applica-
tion of pressure around the hole of the material; c - Drawing of the naterial;
d - Finishing stage of the drawing process
are assembled in mating stacks and the holes are drilled to the final dimensions,
whereas in simultaneous dimpling the holes are drilled ,immediately after .the dimp-
ling.
Before any work on dimpling is started, the working parts of the punch and dies
must be checked for proper function by dimpling sample' recesses in some specimens.
The described group of tools for dimpling does not fully meet the quality-re-
\
virements of recess raking and has the following drawbacks: STAT
1) Buckling of the material after dimpling;
2) Presence of burrs around the holes, resulting in the formation of radial
95
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4,
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ct-
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,
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4
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cracks after dimpling;
,30 Wron dimensions of the recess, in some cases.
The drawbacks mentioned are partially eliminated when using tools of the sec,.
group, shown in Fi'Y.87.
:1111111111
11111111111111 =MC
Fig.89 - Tool Set for
Dimpling
1 - Punch; Uolding
plunger; 3 - Die;
4 - Spring; 5 - Washer
with stem
In this case, radial cracks arc eliminated by holding the
part tightly in place by the plunger. During the first
stage of dimpling, the material is being pressed into t:e
area around the hole, and as the plunger moves further,
drawing of the material takes place. Elastic dcforration
is therefore less than in the case of dimpling with tools
of the first ;Troup.
To reduce elastic deformation and buckling of the
planking raterial around the recess, the pressure during
the initial stages of dimpling is absorbed b7 a rubber
sleeve or support around the plunger (Fig.88). The tools
shown are operated on the same principle as drawing dies.
The third group includes tools working on the principle
of crimping the holes by embossing. The tool shown in
Fig.89 consists of a punch (1) and die (3), whose hole car-
ries the plunger (2), held In extended position by the
spring (4), which rests.on.the masher (5). The dimensions
of the tapered part of the punch correspond to the dimensions of the rivet head. The
pilot stem of the plunger is chamfered at an angle of 2? to facilitate the release
of the part after the recess is formed. The working- surface of the punch in contact
with the raterial is rade concave and that of the mating die is made convex for the
purpose of avoiding the bulging out of material in the area around the recess.
r of the conical part of the recess of the mating die is the
h,(1), it is possible to use one set of tools for sisTATn-
dimpling of recesses in sheets having a thickness from 0.5-1n11i.
F-1S-10032/1T?
96
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The plunger with the pilot stem ensures a tight hold of the material at tie
ed:es of the hole, during the entire travel of the plunger. The initial tension
the spring on the plunper may vary from 60 to 80 kg.
As the punch approaches the die (Fig.90), the sheet not only is bent and dra%n,
but is also upset, being coined under pressure and flowing between the working parts
Fig.90 - Schematic Diagram of Procedure in Dimpling With Tools of the
Third Group
a - Placement of the workpiece on the pilot stem; b Beginning of the process -
contact of plunger and die with the, material; c - Crimping and coining under
pressure of the material in the'area of the hole; d - Finishing stage of the
process = the material is upset in accordance with the contour of die .and plunger
of the punch and die. Due to the effect of coining, the resultant recess has a
sharp and well-defined transition line to the surface of the sheet.
Table 18
Diameter of Holes in Dimpling With Tools of the Third Group
(See Fig.89)
Diameter of rivet stem, in mm
2.6"
3.0
3.5
4.0
5.0
Diameter of holes under the pilot
stem of the punch, in mm
2.4
2.7
3.1
3.6
STAT
1 4.5
. The washer (5) with its stem (Fig.89) serves the purpose of adjusting the a-
97i!
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mount of compression on the spring. The degree of spring pressure required depen'
on the kind of material worked, its thickness, dimensions, and the type of rivet.:
Table 19
Dimensions Of the Working Parts of the Dies Used in Tools of the Third Groul
(See Fig.89)
Sketch
Diameter of
rivets,
in mm
_
'Dimensions in nm
DM
dm ?
.
d
P
'-eie
ar"?'
01/
?s_nal
'4111
fldb.
rAV
/41111111111?
d
d
4-m
2.6
3.0
3.5
4.0
5.0
5.7+0.025
6.5+0.030
7.3+0.030
8.2+0.030
9.9+0.030
3.6+0.025
3.9+0.025
4.4+0.025
5.2+0.025
6.1+0.030
2.1;.+0.02
2.7+0.02
3.1+0.025
3.6+0.025
4.5+0.025
used. The correctness of the amount of spring pressure is judged visually from the
appearance of the recesses obtained in preliminary tests (Fig.91). The dimpling with
the described tools is done on holes which have been pre-drilled, whose diameters
must correspond to the diameters of the rivets used (Tab1e.18).
Complete dimensions of the working parts of the tools - punch and die - for
dimpling in power presses are given in Tables 19 and 20. .
Coining enables satisfactory smoothness of surface, but the sharp line of trans-
ition of the surface of the recess to the surface of the planking causes a concentra-
tion of stresses, which lowers the-strength of the joint as compared with joints
made with recesses which have been stamped out with a smooth and even transition
line. The force required for stamping recesses in sheets of 0.6 to 0.8 nm in uhich-
ness are given in Table 21.
98
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Dimpling of recesses, utilizing the rivet heads may be done by the following
two methods:
1) Simultaneously with riveting;
2) 3eparately, i.e., at first the recesses are dimpled with the rivet heacr,
followed by upsetting the rivet with other tools.
.Then dimpling simultaneously with riveting on power presses, the tool shown in
Fig.92 is employed. This tool consists of the set die (1) which has a smooth sur-
Table 20
Dirensions of the working Parts of Punches Used in Tools of the Third Group
(See Fig.69)
--"
face, and the body (4), wAch accorniodates 4 punch. The buffer sleeve (2) is actu-
ated by the sprinc (3), and serves for holdin3 the part being dimpled.
T. c work in using this device is done in the following order: holes are pre-
driile0 in the piece which is tLen placed in the power press in such a way that the
steL of t:.0 rivet fits into the hole of the buffer sleeve., with the rivet head a-
-:ainst the set (lie. The press is started up, causin- the flat surfaceto
of 4F1(7;VPe
'-'escenr1 and t111.5 starm out the recess to the s'spe of tl,c rivet head.
In dirlplinn bv the second nethod in power presses, Sip]er devices, aS sliown
99
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in Fig.93, are used. The procedure of work with such tools is carried out in the
following sequence: As in the previous case, holes are drilled in the piece to be
dimpled, to the diameter of the rivets
used, the rivets are inserted, and the
piece is placed in the power press in such
a manner that the stem of the rivet fits
into the removable die which must have a
Table 21
Force Required for Dimpling on
Power Presses
Diameter of
rivets, in mm
Dimpling force,
in kg
2.6
1900
3.0
2400
3.5
3000
4.0
3800
5.0
5300
the parts are moved to another
conical hole of the same shape as the in-
serted rivet head. As the press is started
up, the flat surface of the set die de-
scends, thus stamping out the recess. After
power press which is provided with a mechanism
for riveting, and t'le riveting operation is performed on the entire piece worked.
4. Countersinking the Inner Sheet and Dimpling the Outer
By this method (see Fig.65c), the fornation of the recesses underneath the
heads of flush rivets is carried out on each of the mating parts separate17. In the
parts of the airframe which are of greater thickness, the recesses are countersunk
while in the thinner skin the recesses are dimpled. Since the countersunk recesses
are completely filled by the rivet heads as well as by the material of the outer
sheet, using the tools of tlie first group for dimpling (see Fic.85).will ,cause the
recesses to be countersunk deeper than in conventional countersinking, bfr 0.461, -
where 51 is the thickness of the outer sheet being dimpled.
To obtain greater surface smoothness of the planking at the edges of the coun-
tersunk recess, these edges are chamfered to a depth from 0.3 to 0.5 mm. In that
case, the dimpled recess in the planking will fill the countersunk recess in :riocr
airframe corpletely.
taper angle of 1500.
The chamfering is done with a countersinking tool, having a
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9) for diipling the planking, the depth of the cOUn-
0. .4
ilici,iififrime depends ?n the type and diameter of the. rivets. used .
The process of dimpling and counter-
sinking recesses and the use of toai-hnd
instruments in connection with this opera-
tion, does not differ from the process
described above.
, ,Fig.91 - Determination of Correct
' Spring Pressure in Tools Used for
Dimpling by Visual Inspection of
ReceiSes Ehde in Test Specimens
- Insufficient spring pressure;
5. Dimpling in Ehgnesium'AlloY Parts
The magnesium alloys of specification
MA-1 and MA-8, used in structures, have
only a limited dimensional stability at
dimpling.
b - Correct spring pressure; c
!Ex?
cessive spring Pressure
1is done cold in magnesium alloy parts.
Such defects weaken the riveted joint and disrupt the surface smoothness. For thi
*ion, magnesium alloy parts are stamped by pre-heating the area of the metal.
":-The pre-heating of the stressed area can be done by resistance heating or by
contact heating.
- In resistance' heating (Fig.94), an electric current is passed through the
stressed area of the Sheet from oppositely placed electrodes which function as the
source of heat. One electrode is connected-to the conical 'section of the punch and
the,other to the mating die; when these come together and make contact with the
STAT
edges of the drilled hole, an electric current of considerable magnitude pass..
thiTiiigh the resistance offered by the metal. The greatest resistance is-in the area
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. .
?
"'m""74-VN4Egggr"
w'ere the edges of tie hole are in coqtact with t:.e punch, which results in heu:
this area of t:e sheet to te highest temperature.
The temperature to which t'e
should be heated depends on tl-e t7-pe? of rateri,_'.
For dimplinr parts of :a-1 alloy a temperat
of 325 - 375?C is required, while dirpling of
parts of 1i-8 alloy (annealed), requires rai3in;
the terperature to 30C - 350?C. In dimpling by
the electric resistance method of heating, a
transformer with a power rating of 10 - 15 kw is
required, which permits pre-heating the parts by
bringing them to the required temperature within
0.5 - 1 sec.
The process of dimpling by the electric re-
sistance method is carried out in the following
Fic.92 - Device for Dimpling
Simultaneously with Riveting
in Power Presses
1 - Set die; 2 - Buffer;
3 - Spring; 4 - Body
sequence:
1. The parts to be dimpled are placed between the punch and the die which are
integral with the mechanism of the power press. Then the part is placed on
the pilot stem of the punch, through the hole;
2. The part is tightened under pressure between the punch and die and the area
of the metal to be deformed is heated;
3. The recess is dimpled;
4. The punch and die are retracted to their original open position.
Then, the recesses are dimpled over, the entire part worked.'
Pre-heating of the sheet by the contact method (Fig.95) is accomplished by the
transfer of heat from a previously heated device. The intensity of the heat trSTAT
fer from the device to the sheet depends on the temperature differential and on the
area of the sbrfaces in contact, the material of the device, the pressure existing
102
I
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between the heated part of the device and the sheet, and on the thicknesl-, or
sl:eet. The plunger an0 the die in that case are rade with a wider area of ccr'
Fig.93 - Dimpling With the Rivet Eead
a - Starting position; b - Dimpled recess
When pre-heating by the contact method, the temperature of the punc:i and the
die material must be higher by 20 - 30?C than the temperature of the area if the re-
cess were dimpled by the resistance metnod. Under
these conditions the heating is done within
8 - 15 sec.
The process of dimpling when pre-heating by
the contact method is carried out in the follow-
ing sequence:
1) The heating device is brought to the
required temperature in special heating
equipment;
.2) The part to be dimpled is so aligned
that the pilot stem of the punch fits into
the previously drilled hole;
The part is held tight between the punch and die, and the area of deforma-
'STAT
Fig.% - Schematic Diagram of
Heating Parts by the Electric
Resistance Method
1 - Punch; 2 - Transformer;
3 - Potentiometer; 4 - Power
line; 5 - Switch box; 6 - Die
tion of the sheet is thus pre-heated;
4) The recess is dimpled;
5) The pinch and die are retracted to the original positidn and recesses are
the entire. piece.
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Sketch; b) Section through a - a; c) Section through a - a; d) Conical angle cc ; e) Rivet diameter
7m; f) Thickness of; g) Dimensions in mm; h) Die; i) Punch; j) Tolerance on D1; k) Tolerance on d1;
1)-Tolerance pn_Do; m)-Tolerance on do
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? - _
of the Working Parts of Dies and Punches for Dimpling with Heating by the
a) Sketch; b) Conical angle ce; c) Rivet diameter in mm; d) Thickness of stamped sheet stack; e) Di-.
mm; f) Die;,g) Punch; h) Tolerance on d1; j) Tolerance on Do; k) Tol-
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- 4Tere.4,445?4Wk4:40:17-62."7,--
? - .4 -4,
The accuracy and cleanliness with which the punch and die are prepared infi.-
ences the quality of the dimpled recess to a considerable degree. Tables 22 and
give data on the shapes and dimensions of the working parts of the tools used for
Fig.95 - Schematic Diagram of
Pre-heating Parts by the Con-
tact Method
1 - Punch; 2 - Heat transfer de-
vices; 3 - Regulating control
dimpling of various types and dimensions an
by different methods of heating.
Before any work is started on dimpling of
parts, it is necessary to make sure that all
equipment is in good working order. This in-
cludes all tools, instruments, fixtures, the
equipment which serves as a supply of heat to
the punch and die, from which the heat is
transferred to the material worked, as well as
the performance condition of the regulating
instruments. The adjusting of the equipment is
box; 4 - Die; 5 - Thermocouple;
done by dimpling specimens of the same material
6 - Power line
and of the same thickness as the part on which
the dimpling is to be performed. After checking the accuracy of the test recesses
by .means of calibrated rivets and making certain that there are no cracks on their
,
surfaces, the dimpling operation can be started.
Dimpling of recesses under the rivet heads by pre-heating, in accordance with
the technical procedure outlined above, can be applied to other materials which have
a limited ability to withstand changes in shape at normal room temperature.
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72:1:4;7
. TYPES OF RIVETS IN USE AND THEIR MANUFACTURE
1. Types of Rivets
Depending on the degree of ease of access to the place of riveting, various
types of rivets are used. For riveting in open places of structures, where it is
possible to approach the work from two sides, rivets with solid shanks are used
(Fig.96), which represent approximately 97% of the total number of rivets used on
- ?Types of Rivets with Solid Stems
STAT
4. - Flush type,
a = 1200; 5 - Double cone, a = 1200/1640; 6 - Flat head with high shearing strength;
7 - Blind rivet; 8 - Flush type, a = 120?, with high shearing strength; 9 - Sleeve
,
for rivets with high shearing strength; 10 - Plano-convex type
. .
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K
w
?
_
_Lconventional structures of light alloys. The rivets shown in Fig. 97 are used for
--riiiting in enclosed portions of the structures, i.e., where it is impossible to I::
7:
rivets with solid shanks and where the riveting is done from one side only.
;Depending on the fit of rivets in certain structures, rivets with various shalt,
? ,
_Jof heads are used, known as protruding and as flush types. The'protrudingtype in
28--
Fig.97 - Rivet Types foxj Riveting From One Side
1 - Mandrel with hollow round-head rivet; 2 - Mandrel with hollow flush-head rivet;
30-
-
32_
3 4__
3 - Tubular rivet with flat head; 4 - Tubular rivet with flush head; 5 - Explosive
Rivets
36__
38--,cludes rivets with semicircular, piano-convex, and flat heads. Such rivets are used
40 or joining parts of the airframe which are not exposed to the air flow.
42111Flush-type rivets are subdivided into rivets with a cone angle of the recessed
44IIJ1ad of a = 900, rivets with a cone angle of the recessed head of a = 120?, and riv-
46 s with two cone angles of the head of a = 120?/164?.
48 -Flush rivets are used in the following manner:
STAT
50 1) Rivets with heads having a cone angle.of a = 90? in countersunk recesses;
A-
2) Rivets with heads having a cone angle of a = 1206 in countersunk and
54
impled-reeesses;
56J ? )-Rivets-vith-heads7having-two angles a = 1200/1640 only in dimpled recesses.
. t
--T110
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Standardized Code Designations of Rivets with Shanks
2006A50:
2024A 50-
2000A50
2013A50
2020A50
2030A50
2007A%
2025A50
2001A 50
2014A50
2021A50
2031,A50
a) Type of rivet; b) Standard code designations; c) Aluminum alloys; d) Steel; e) 15A and 10 cold-hardened;
f) Copper M2; g) Half-round head; h) Plano-convex head; i) Flat head; j) Flush type a' = 90?; k) Flush
:type a= 1200; 1) Double conical head a = 120?/164(); m) Flat head with high shear strength; n) Flush type
, with high wear strength, a = 90o; o) Flush type with high shear strength, a = 120o; p) Rivet sleeve with
_
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Flush rivets are used principally in riveting the streamlined surfaces of air-
craft. exposed to the airflow, such as in joining the skin to the fuselage frame.
Roughness of the outer surface of high-speed aircraft increases the drag. For
this reason, one of the fundamental conditions determining the quality of the outer
surface of the aircraft, is the use of high-precision flush rivets; 65 - 70% of ti-Le
total number of rivets used in the construction of aircraft is of this type.
The use of flush rivets in conjunction with accurate holes and recesses result
in a seam of high-quality workmanship.
Rivets used in the construction of aircraft are standardized. The standards are
differentiated by a definite letter and number code, classifying the rivets by the
type of heads, kind of material, diameter, and length (Table 24). For example, the
designation 2006 A50-4-18 is decoded as follows:
1) The number 2006 signifies a round-head rivet, made from material V65;
2) The letter A signifies its use in aircraft manufacture;
3) The number 50 is the year of issue of the standard (1950 in the given case);
4) The figure 4 refers to the rivet diameter;
5) The figure 18 refers to the rivet length.
2. Materials for Rivets and Their Identification Marks
? The material for rivets, is wire of aluminum alloys and of various kinds of
steel, manufactured in accordance with the technical specifications in Table 25.
The chemical composition and mechanical properties of rivets manufactured from
the materials listed, are given in Tables 26 and 27.
Rivets made from V65 and D18 alloys are used in riveting strong joints (such as
the skin of the airframe, parts of longerons, ribs, tie components, and major units).
Rivets made from these alloys are characterized by the fact that they can be used
for riveting right after their aging period, and that throughout their entire storage
period no re ted h treating is required. This property is quite important since
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49,
40'
Wrisulta.,in, simplification and in lowerLg the cost of production.
, .
vets-of ANts alloy are used principally for riveting welded containers and
Rivets of ANg5 materials are normally' .used for joining parts consisting of
ignsium alloys.
-Rivets .made from steel of specification 15, 10 (cold-hardened), 20GA and
?
-= 1M18N9T,'which possess high strength, are used in joining steel components and mixed
26?
U 3?-
32_
8 4_,
36:
401
427.]
_structures, i.e., structures in which aluminum alloys and steel are used in combipa-
.44_1
-1
-A Rivets of material 30KhGSA which possess high shear strength are used in struc-
SIWT
high shearing forces, such as in longerons, heavy ribs, etc. Riv-i
ilaterial
I
Identification marks
of material
Technical specifi-
cations for wire
Aluminum alloys
Steel
'
' Copper ,
V65
D18, AMts,
15A (select)
10 cola
30KhGS(1
1Kh18149T
M2
Amg5
20GA
-hardened
(aalT)
I
265 .ANTU-49
349 SMTU
ChMTU 100
ChMTU 285 .
MPTU 2333-49
MPTU 2320-49
.
GUST 770-41 ,
--itures subjected to
Hets having high shear strength may replace bolts, since they are lighter in weight,
and more economical in production work. In applications where the
subjected to tension stresses, it is not recommended to use rivets
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Chemical Composition and Mechanical Properties of Aluminum Alloy for Rivets
a).Type-of material; b) Chemical pamposition of alloy in %; c) Physical properties; d) Not more than;
e) Total other ingredients; f) Ultimate unit stress in tension ab, in kg/mm2; g) Relative elonga-
tion in %, 610; h) Stress in shear T, in kg/nmi2; i) Remainder
Chemical Composition and Mechanical Properties of Steel for Rivets
a)
b)
d)
C -
Si
Mn
P
S
Cr
Ni
Ti
e)
f)
.
...
g)
c)
15A (5elect)
0,15-0,20
0,17-0,37
0,35-0,65
0,035
0,035
0,20
0,30
?
45-60
3
34
20A
0,18-0,26
0,17-0,37
.
1,30-1,60
0,035
0,035
0,020
0,30
?
?
19
47-55
30XGSA
0,27-0,32
.
0,90-1,20
0,80-1,10
0,030
0,030
0,80-1,10
0,40
?
125
10
0 510
72
1X18N9T (Yarit ).
>0,14
,
> 1,0
> 1,5
.0,035
0,03
17-20
8,11
0,8
?
?
.
> 44
Chemical composition of alloy in %; c) Not more than; d) Physical properties;
in tension ab, in kg/mm2; Relative elongation 6 in % (/ = 100 mm);
ar zap.
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. 44,F.14;=ZA164,,C,,
_ Jo-
- 12--
t
a
--
r's?
.4".%
e's
se??
?-?
e'??
t.
..upou
11.
ng I having a high shear strength.
TO facilitate a material identifi-
cation of the rivets, the rivet heads
4.).5 have definite marks. The marking is
214 done during the heading operation, in
V
the form of a coded design which may be
rx
raised or indented dots and rectangles.
? It
Table 28 shows the marks specified as
,.
standard for rivets.
c
? 7:$ 1
These identification narks permit
o i
?-.. !!! .
?9 i selection of the proper type of rivet at
0,?.
O,X any stage of production, beginning with
V
Ag pt. the heading of the rivets, and channel-
!
'A Vi Ki ing the rivets to the proper job. Flush-
0-PC.)
O 1
1. type rivets have marks depressed in the
?r"-)
0 0 head, since they are used for riveting
TH
H the fuselage skin for which rigid re?
quirements as to surface smoothness are
H ?rt
0 made. These markings are an aid in the
-P
ctjcj
4-1
inspection of the rivets during their
O -
'0
manufacture as well as of the entire
i?j? ti
al 0 riveted joint.
A distinguishing feature of the'
most widely Used V65 alloys of aluminum
47) and 15A of steel is the absence cSTATT
stamped marks.
? +3
All above statements refer to riv-
MrCil
ets with solid shanks. Rivets intended
"aD
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?-;
'13 ?
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-
-
AA.17rZI.V.
-
?
to,
L. -
for riveting from one side only and rivets subjected to alternating stresses, as wp
as other types, will be investigated in detail in the appropriate Sections of this
book.
3. Established Rivet Requirements
.Rivets must meet the corresponding requirements as set forth by the technical
specifications 53ATU-5l.
As to exterior appearance, rivets must have a clean and smooth surface, without
cracks, scratches, flakes, blisters, beads, and rough surface stains which is an in-
dication of incipient corrosion.
In dimensions and tolerances rivets must meet the requirements corresponding to
the riveting job specifications. The shanks of the rivets must be straight or of
circular cross section.
Bright spots are allowed on the rivet heads which are due to incomplete contact
with the punch head during upsetting, provided they do not affect the minimum dimen-
sions. Slight fins, which are caused in upsetting and are not fully removed in ro-
tary polishing with an abrasive, are tolerated provided they do not affect the dimen-
sions of the rivets within the specified limits. In addition, the following defects
are tolerated:
'a) Insignificant hollow depressions and traces of marks of the upsetting dies,
provided they are' within the limit of one half of the allowed variations in
the specified dimensions;
b) Deviations from the perpendicular of the face and the seating surface of
the head, as well as of the flat end of' the shank by 30/ with respect to the
shank axis; STAT
c) Out-of-round of the shank, within the limits of permissible deviation of
the diameter. .
117
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:1-17 . - - ?
4. Manufacture of Rivets and Their Heat Treatment
Rivets used in the assembly of light alloy sheets are made by the cold upsett,ng
process from wire stock. The diameter of the wire is somewhat smaller than that of
Table 29
Die with Inserts of Hard Alloy for Heading Flush Rivets on Automatic Machine 52VA
? Old_ans
a.
,
f)
I
d1
ct,
e)
cl)
h)
q)
h)
1
90n+ io
2,6
? 3
3,5
4
2,59
2,99
.3,49
3,99
+0,03
4,6
5,2
6,1
7,0
14
20
5
6
4,99
5,99
+0,05
8,8
10,5
26
120? 4 1,5?
2,6
3
3,5
4.
2,59 '
2,99
3,49
3,99
?
'
+ 0,03
5,35
6,1
6,9
7,8
?
+0,06
14
20
5
4,99
+0,05
9,5
26
a) From both sides; A)) Insert; c) Body; d) Hole; e) Specified diameter ofts
d, in mm; 0 Dimensions, in mm; g) Specified; h) Allowed deviatiOn
the fabricated rivet. This is done for the purpose of facilitating the entry of the
wire into the openings of the upsetting dies.. The surface of the wire must be ;bright
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A
tfi
46r?ela,
"".
'
--
and-iust show no traces of oxidation. The-r
appearance of apparently insiOificant
-
a
langitudinal on_steel _wir_e_and. more_
F
64_
12
1 4L
16
ase
432
424,
0,1"
a) A
\Ill I
e)
0 8 11 24
c)
32 48 82 SO
18 'Fig.98 - Wear .of Dies of Material
20 Kh1214 and in Dies with Hard-Alloy
22 Inserts, as a Function of Working
24-- Time
:a) Wear area A; b) Amount of wear in
26HS the area A, in amq c) Work time of
3OII dies, in hours; d) For die Kh12M;
32 e) For die of hard alloy
icUlar1y_ on chromium-molybdenum wire,
is one of the causes of the development of
4
34
36
3
.40
'42
44
heading machines are
tions of the rivets,
--duction.
cracks during the further cold-working in
the riveting operations.
Fthdamental factors which determine
he quality of fabricated rivets are as
follows:
1) Quality and size of the wire used
in heading the rivets;
2) Qrplity and accuracy of the work
in preparing the heading tools;
3) Accuracy of the automatic heading
machine;
4) Technical procedure in the further
work on the rivets.
The dies and punches of automatic
the basic tools whicli determine the dimensions and configura-
so that special emphasis should be placed on their correct pro-
Higher stability to resist wear. and maintain dimensions of the rivets is at-
tained if the dies are made with inserts df hard-metal alloys. A general view and
practical dimensions of a die of this type are given in Table 29.
48=1 .Tests made on dies fitted with inserts of hard alloys have shown that they have
46_1 .
--greater durability than dies made of Khl2M steel, (Fig.98). For example, in STAT
50-
52--
54
-hour period of work, the amount of wear in the area A of the die was as follows: ?
For the die fitted with hard-alloy inserts,
For the die made of Kh12M steel
0.02 nun
0.34 mra
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- - -
? - ? ? ? -
!
-.--
m
IKTIIEWA
I MtRU
*
1
8
12 16 20 24 28 32 36 40 44 4.6 5(
0
-,
,
, I , ,
Fig.99 - Wear of Dies with Hard-Alloy Inserts in Heading Rivets
a) Wear in mm; b) Wear on hole diameter dm; c) Wear on height of recess under
rivet head hm; d) Wear on diameter of recess under rivet head Dm
Fig.100 - Automatic Rivet-Heading Machine
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^
4.1
II.
ref-
-
This shows that dies fitted with hard-petal alloys have almost 17 times as much
service life as similar dies made of Kh12M steel.
Figure 99 shows characteristic curves for the wear of dies in heading machines.
The curves indicate that during the working time when the dimension dm increases, the
Fig.101 - Formation of the Head Of Fig.102 - Formation of the Rivet Head
the Rivet on Single-Stroke Automatic on Two-Stroke Automatic Headers
Headers a - Wire stock installed in the die;
a - Wire stock installed in the die; b - One third of the height h upset;
b - Upset head c - Upset head
dimensions Dm and hm decrease. An analysis of these curves shows that in dies with
hard-alloy inserts, their wear has no significant effect on the dimensions of the
rivets for all practical purposes, since
Fig.103 - Position of the. Rivets Be-
tween the Punch and Die at the Finish-
ing Stage in the Heading Operation
this wear is only 0.05 mm. Such dies are
usually removed from service because of
splitting or cracking of the hard-alloy
insert. The material used for making the
inserts in the dies is the hard alloy VK8
or VK10 of specification GOST 3882-47.
STAT
The rivets are manufactured oil
cial automatic heading 'machines (Fig.100).
Automatic headers are classed according to the number of strokes, as single-
stroke and two-stroke machines. The operating principle is the same in single-
stroke and in two-stroke machines. The difference consists in that single-stroke
121
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7.,
ang.
,
8?
, ?
-10,?.
'
2 ?
4,4
- 16 77-,
'18 _
- ? 22
24--
__chine is operating correctly, keeping the Imechanism lubricated, and changing the
26_
_punch and die tools as necessary.
28-
30 Determination of Precision Characteristics of Automatic Heading Machines
(412'
????._..1?,..-- ? ?
machines have one. punch which heads the rivet in one stroke (Fig.101). Two-stroke
machines have_two punches, one for the_preliminary and the other for the_f_inishing
operation. The preliminary punch aligns the stock in the die and at the same time
-
heads the shank by 1/3 of the usual iie h to form the head; -then the finishing
punch, by a second stroke, gives the head
its proper shape (Fig.102). The rivet
heads have a more correct outline when made on the two-stroke automatic headers than
on the single-stroke machines.
The position of the rivets between the punch and die at the end of the heading
operation, is shown in Fig.103. -
The heading operation in both the single- and the two-stroke automatic machines
is carried out automatically throughout. The supervsing operator is charged only
with the initial setting up of the wire in the machine, with checking that the ma-
The accuracy of the rivets manufactured on automatic headers is checked during
34_
1
36_ Form 1
Form for Ehtering the Results of Measurements in Determining the Preci-
40__
42-
44
46
,48]
521
sion Characteristics of Rivets on Automatic Headers
Xi
in
Xillt
Xi ? X
(Xi ? gr
(Xi ? -;V)tM
?
_
?
'
Total
- 1 mn
I Xim
13 (Xi ? Xrni
STAT;
(41bi4?ttheir-operation by numerous-(usually-fron 150 to 300) measurements with micrometer
indicating_dnstruments .to determine an deviation from the control caliber. The
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:r
?
"taw
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.7.4t-I V
711
tehr- -
772.1-171V:74.
_ ?
_
measurements are made on rivets from one coil of wire made on one die. The micro-
meter is set to the zero point on the first rivet produced, and measurements of sub-
sequent rivets will then indicate the deviation relative to the first rivet. The re-
sults of the measurements are entered on Form No.l.
The following symbols are used in Form No.1:
X- - Deviation in the measurements of the rivet head relative to the calibrated
specimen, in mm;
in - Frequency of deviations;
Xim
X-
m - Arithmetic mean for the experimental group, in mm;
,I
(X-X ) - Deviation from the arithmetic mean.
After entering in the Table the measurements and making the proper calculations,
the error is determined by the method of least squares, from the formula
1 =
VS(Xr--5-0t m
m
?
The magnitude of 6aindicates the scattering of the results of the actual mea-
surements.
Investigation* on determining the precision of the automatic header in the man-
ufacture of flush-type rivets (Table 30, Fig.104), show that it is possible to ob-
tain rivets with much closer tolerances (with respect to deviations Ah of the heads
of the rivets from the calibrated control) than required by the established standards
for rivets.
Inspection of Rivets by the Statistical Method
In view of the fact that a considerable quantity of rivets is used in the pro-
duction of aircraft, and that the manufacture of rivets proceeds in accordancnHh
'a systematic sequence, to definite specifications on a large scale, it is obvious
that the adoption of the statistical method of inspection is quite rational. This
* Investigation made by Ehgineer Bayemanov
123
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1
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EurAtt
MEP
-
I
--
C
Table 30
&le of Recording the Precision of Automatic Headers
xi
a)
c)
t.
-0,004 //// 4 ?5 -0,0175 -0,00700.000049 0,000245
-0,003 / 1.
-0,002 ///1/// 7 11 -0,0165 -0, C050 0,000025 0,000275
-0,001 1111 4
0 101111111Y 14 25 0,0375 -0,0030 0,000009 0,000225
+0,001 /////////// 11
+0,002 ///////MW//////////////// .28 40 0,1000 -0,00100,000001 0,000040
+0.003 //////////// 12
J-0.004 ///////////////////// 21
+0,005 //////// 8
+0,006 //Mifili/////// 17
+0,007 ///////
? +0,008 //MN
+0,009 ///
+0,010 IN
+0,611 I
40 Total
15012 =0,53551 1E0,00550
1 29 0,1300 0;0010 0,000001 0.000029
24 0,1560 0,0030101mo 0,000216
38 11
0,0935 0,00,50
0,000025
0,000275
1 5 0,05251 0,007+,(000491 0,006245
4
Xim 0,5355
-0,0035;
m 150
a 3= V 2 m
VI-Em
0,0031;
? 150
61 0,019.
a) Marks; b) Frequency; c) Total measurements.in groups; d) Total
1 _method contributes to the quality of the product, reduces rejects, and result:STATI
5
-
_ reduction of labor in the inspection of the rivets.
Essentially, the statistical method of inspection of rivets during their pro- !
,cess.of_manufacture_consists_in_rating the_rivets_on the basis of measurementS_Pf-__
their parameters-on-a-selected-smallf-numb?r- (usualay-10-to-15-rivets-)-frca-the-1-arge
\
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---------.
?'?,--In-audh?cases, the method of statistial analysis is applied to the_character-
t ?
stids...of? a main number of selected samples, after which a relation is established
_ ,
Fig.104 ? Practical and Theoretical Dispersion Curves, Characterizing the
Quality of an Automatic Rivet Header
Number of measurements; b) Practical dispersion curve; c) Theoretical disTAT
?
persion curve; d) Measurement intervals
output,of the machine over the same interval Of time, all of which will possess the
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NMI Mi MO MEW c
=I ME In MI= =I MI= =I MI
NMI MIN MIME NM MIMI MEM=
WI MINIM =MEI= MI MLA IM
IMO WI MIIIIIPIs ri
Full WI IA MINIM r%
111111rM INA LAMA Ell MN MIME IA
MN MIME= MI IIMIIIMIrm ion mi
IMMO MI MI =ILA
MINN NM
MINIMMIIMI no ma NE MIN MINIINW.7."?a
?
1111?11-1?111111-----
MI NM? --111111? EMIL Ye
1111111=11IM NM MEM MIME IIIII
MIN I= =I EMI NM
MINIM NMI MIMI= INN MIME =I
MI NMI EMI =MIMI MI
MI MOM ME =I MIN INN OM
INN IMMI MI= NMI 1E1 IIMI ION
OM NM MI MIMI MIN NM =MIMI
INN Ell MI I= MINIM =MEMO
Eli MIN liim 11111111111111 lila
In OM nu PM ME
MIMI= rirsrIlry LA LA re
ry rum hdl LAI La IA INN LA
ass LA LA MIMI MI EMI INN MO=
In NIB NM MI MEI MI IIIIII MIN
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IINIM wig imam Ma aim vi.r,
lila NM I= IM IN =MIEN
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;? r
a) Statistical inspection chart; b) Section No.; c) Equipment; d) Type No.; e) Part; f) Name; g) Rivet;
h) For measurements; i) Technician; j) Code; k) Number of rivets in selected group; 1) Working period for
selection; m) ACOlster; n) Rivet diameter; o) Height of head; p) Sketch; q) Example; r) Fins; s) Skewing
of head; t) Cleiness; u) Cold-hardening; v) Cross section; w) Time in hours; x) Diameter of head;
y) Rivet lei.tbh; z) Inspection foreman; aa) Inspector; bb) Female assistant; cc) Repair workman
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?
A record of the correct procedure of rivet manufacture is kept on special sta-
tistical records or charts (Form No.2).
The data on these statistical inspection charts are worked out in the technical
section of the rivet manufacturing plants, thus maintaining a continuous record on
the quality of production. The upper and lower tolerance limits are shown on these
charts in heavy lines,
and the inspection data are entered between the lines. The
decision as to whether or not the rivet
Fig.105 - Measurement of the Devia-
tion of Rivets from specified Size
in a Calibrated Gage, Using an In-
dicator
1 - Master gage; 2 - Indicator
dial; 3 - Pedestal support of
indicator
a) The dial of the indicating in-
strument is set at uzeron
where xl, x2, x3 ..., xn
n is the number of
output is in accordance with quality specifi-
cations is based on the inspections of a
few selected rivets on any one run of the
machine.
The checking of the dimensions of the
rivets is done by the inspection department
with conventional measuring instruments,
such as micrometers for diameters of the
shanks and the heads, and slide calipers for
measuring the length. A special indicating
device is used for determining the height
deviation of the rivet head from the speci-
fied dimensions (Fig.105). The dimensions
of the working parts of the gage used in
,rivet inspection are given in Table 31.
After all dimensioning of the parame-
ters of the rivets is done, the arithmetic
mean of the selected group of rivets is de-
STAT
termined by the formula
? A-x2?x24- +x?
x
IZ
are the measurements of the rivets in the group;
rivets in the selected group.
1.27'
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rr,,t
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STAT
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....11.11W.
_ ? "
k
,
Table 32
Common Defects During Manufacture of Rivets and Remedies
_
I
Type of defect
Cause of defect
Remedy
Flat surface of head
skewed with respect to
rivet axis
Punch of finish heading
installed crooked
Install punch so that the
working surface is in con-
tact with the die surface
without clearance and prop-
erly aligned
Cracks in the rivet head
Wire not sufficiently
ductile
Check the chemical composi -
tion of the wire and make
several mechanical tests
1. Rivet head of ellipt-
ical shape
2. Lines on the flat sur-
face of the head
Flat surface of punch
has tool marks which
interfere with the flow
of metal during the
heading process
Finish and polish the flat
surface of the punch
Rivet shank has longi-
tudinal lines and traces
of annular grooves
1. Longitudinal scratches
on the wire
2. Traces of tool marks on
the inner surface of the
bushings
3. Excessive feed-roller
pressure on the wire
1. Change the coil of wire
2. Change the bushings
3. Reduce pressure on stock
feed rollers
Incomplete rivet head
1. Insufficient movement
of the guide block
2. Insufficient outlet of
mire for the formation of
a full head
1. Increase the stroke of
the reciprocating movement
of the guide block
2. Increase the length of
the wire feed
I. Wire stock does not
enter into the die
opening
2. Rivet shank is bent
1. Diameter of stock is
greater than die hole
2. Diameter of wire is
less than die hole
Change to the wire type
Fin on head not removed
in drum polishing, al-
though the punch is ad-
justed correctly
1. The setting of the
wire stroke limiter at
the intake side of the
die not adjusted prop-
erly
2. Cutting edges of the
knife have become dull
1. Adjust the setting for
proper feed of stock
2. Change the cutoff knife
STAT
.
1
Insufficient length of
rivet
Insufficient length of
stock fed to machine
1
Adjust the setting for pro1-1
er feed of stock I
--
129
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?????
_
Type of defect
?
Cause of. defect .
.
_ JlermAY___
_
Uneven length of rivets
after upsetting
. .
,
Slipping_of_the.wire__ _
takes place at cutoff
1
point 1
.
___1.. Inc_rease the brakipg
force of the stock-feed
mechanism
2. Increase gripping force
on wire stock
-
Rivet head displaced
with respect to center
line of shank
Improper position of
punch in the finish
heading stage
Adjust position of punch
with respect to center of
die
Fin formed on head
exceeds allowed size
Surplus of stock for
formation of the head
Adjust feed mechanism of
wire
The arithmetic mean is entered on the statistical inspection chart. If the
mean figure SE is within the limits of tolerance, the machine output is correct. If
the mean figure is outside the upper or lower tolerance inspection limits, (U.T.I.L.
or L.T.I.L.), but is within the set allowable upper and lower limits (A.U.L. or
A.L.L.), the inspector must give a warning signal to readjust the exit mechanism of
the heading machine. In the first and second
Fig.106 - Schematic Sketch of
a Polishing Drum
1 - V - belt; 2 - Electric
motor; 3 - Polishing drum
1
cases mentioned, the rivets are segregated and are
counted as acceptable.
If, however, the average figure is outside
the allowable upper or lower tolerance limits, the
inspector must immediately order readjustment of
the header mechanism. In that case, the rivets
produced between the two check periods are seg-
regated from the regular machine output and are
set apart for sorting as "suitable" and "scrap".
STAT
In addition to inspecting the rivets by their parameter measurements, a visual
inspection of the exterior appearance is also made, and the results observed are
entered in the statistical inspection chart (see Form .No.2).
130
A q
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"
As stated above, as soon as deviations
2
,jpaljnspection chart occur, further work on
,- the defects are eliminated. In such oases,
_
:treasons for the deviation and determine
'
from the standards shown on the stati:
the heading machines is stopped until
the maintenance workman must define th',
remedy. Table 32 lists common defects
8
_. which arise in the process of rivet heading, together with the remedies. FollowinE
10--
the heading operation, the
12-n
land to anodizing.
14__
16 _RotaryDrum Polishing
rivets are subjected to drum polishing, to heat treatment,
18_
Drum polishing and cleaning is one of the important operations, and has a marked
influence on the quality of the rivets. In this process, any fins and burrs remain-
ing on the rivets after heading, are removed. The removal of the burrs and fins is
effected by rolling the rivets in special drums filled with abrasive particles or
2
22
24-
-
26
_Jsawdust. Figure 106 gives an outline of a mill in which the rivets are polished in
28--
__rotary drums with mood shavings, using the following process:
30_1
322] number of rivets and shavings should not exceed one third of the volume of the drum.
By rotating the drum for about 25 to 40 min, the fins and burrs are removed from the
ivets. The time required for the polishing operation depends on the size and shape
34
36
3
The rivets, together with the oak shavings, are charged into the drum. The
--of the rivets, the nature of the adhesions, the rivet material, their contour, shape
?40d
42
44
of the drum in the mill, number of revolutions, condition of the inner surface of
the drum, and the species of the wood from which the shavings or sawdust is produced.
-When a large quantity of rivets has to be polished, the milling installation con-
46
DsiSts of a number of revolving drums mounted to a common drive shaft.
48
:1 After the rivets are polished, they are screened, separating them from t'sTA-rw-
50-1
-Jdust. The rivets are washed in a kerosene bath to remove any adhering dirt and
5
54
ease and are then immersed in another bath of water, maintained at a temperature
--of 50 - 60?C. Then, they are dried by centrifuging.
-- ?
f.:
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'
1
--
Heat-Treating
TT. 'irm
.7C-???=4-1?... wan ?I?die
?.? ?
.0ga
'IBM
After passing the polishing operation, the rivets are forwarded to the heat-
treating department. Quenching and tempering, together with natural aging, repre-
sent the final operations in the heat-treating process of duralumin rivets. This in-
creases the physical properties of the rivets to their maximum. The schedule fol-
lowed in heat-treating the rivets is given in Table 33.
Table 33
Heat-Treating Schedule for Rivets of Aluminum Alloys
118
V65
c)
495-503? C
515-520? C
0 2-5 film ?20 wan . 0 2-5 mrrt ?30 mfr,.
0 6-10 mm-30 min. 0 6-10 mm-40 min ?
n)
20? 309 C
d)
o)
50? C
4 weeks
3 weeks
r)
o)
10 weeks
3)
II
???
a) Heat-treating schedule; b) Type of rivet material; c) Quenching; d) Aging; STAT
e) Fluid; f) Heating temperature; g) Soaking time; h) Cooling fluid; i) Cooling tem-
perature; j) Temperature; k) Holding time; 1)'Potassium nitrate; m) Min; n) Circula-
ting water; o) Room; p) Weeks; q) C2nditions and time limit for use of rivets in
structures; r) When quenched and aged, without time limit, but not earlier than four
weeks after quenching; s)-When-quenched and aged, without time limit, but
than three weeks by artificial aging or 10 weeks by natural aging
? '132
A
?4
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Rivets made from alloy of AMi5 and AMts brands are used in the tempered cOndi:
tion. The tempering is done fram a temperature of 3.50 to 400?C, maintained for
_Table 34
Schedule for Heat-Treating of Steel Rivets
Type of rivet
material
.
Quenching
medium '
;
Heating tem-
perature, ?C
Drawing tern-
perature, ?C
15A
.
-
-
650
20GA
Oil 1
880
650-680
The heat treatment of steel rivets is, done in accordance with the specifications
for steel rivets 56ATU-48, as per schedule shown in Table 34.
Table 35
Protective Coatings for Rivets of Various Type of Material
' Designation of
rivet material
Condition of rivets
before coating
Protective
coatings
V65
Quenchedd-and naturally aged
at elevated temperature
Anodizing -
?
D18
1
Quenched and naturally aged
Anodizing
.
AMts
1
. Not heat-treated _
Without coating
AMg5
AnnealedI
Anodizing STAT.,
Steel 10
Steel 15A
1
After annealing
F
Galvanizing and
passivating
20GA; 30KhMA;
30KhGSA
After quen1.ching and
annealing
--
Galvanizing and
passivating
- - 1Kh18N9T-(EcYalT)
_Without-coating?
? M2
-Annealed- .
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+KT,
.?_
cir* I,
?
-For steel rivets made from 115A materfal, normalizing or quenchingand anriealing
94 i
- kuma be substituted for the procedure given.in_Table_34.
4' i
----.\ ;Rivets of SalT material are used in the annealed or tempered state. Previously
.-
- :
6_
OEM.
20_
arid gieaer duCiilitys-liach facilitates
the riveting operation in structures.
Protective Coatings
After the rivets are heat-treated, they are given a protective coating. The
type of coating depends on the material of the rivets, in accordance with the sche-
matic given in Table 35.
Physical Tests on Rivets
-94:
After heat-treating and depositing a protective coating on them, the rivets are
26 1
_subjected to physical tests on shear and on riveting. Rivets made from any material
lc. ,
--1 __ are subjected to tests on resistance to shear,
0.0t30_,1
1,5thil,Ild 13
v., with the exception of rivets from AMts and M2
' .....,
fn i ?I- 1 Cf
+
?,T i i I ?et
1 CS
I materials. Rivets with high shear strength,
_
I
5 made from material 30KhGSA which are heat-
3.6-1
75;;----
Fig.107 - Dimensional Tolerance
and Dimensions of the Clinched
Head, in Testing for Riveting ,
Properties
treated, are tested for hardness.
The results of the tests must meet the
standard specifications given in Tables 26 and
27. For shear tests it is customary to pick
10 rivets from each batch (weight of batch, 10
kg).and if unsatisfactory results are obtained
.STAT
.on more than two rivets out of ten, then a further test is made on 20 rivets pieAuu
but of the batch. If the results of the repeated test are unsatisfactory on more
- than two rivets, the batch is scrapped.
Tests. on the riveting properties are made on rivets of all types of material,
134
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5
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Tr-rrisr -
'
sr t:
_
to+
with the exception of those possessing high shear strength. The testing of riveting
properties is done on power presses in plates of material 30KhGSA, in which the
holes must be of such a diameter that the rivets will fit snugly. The allowed mater-
Fig.108 - Drawer for Rivets
ial in the length of the rivet shank, 1.2 d, must be used up only for the formation
of the clinching head of the rivet (Fig.107).
After the riveting, the clinching head must be free of cracks and chips, and in
planview the shape of the head must be round. When defects in the clinched head
occur in as little as one rivet out of 20 inspected rivets, the batch is 'rejected and
scrapped.
The finished rivets are forwarded to the warehouse section of the plant, to-
gether with inspection rating charts for each batch of rivets.
5. Working Arrangement for Riveting
In the departments where assembly work is done by riveting, the rivets are
stored in special racks. Each rack is equipped with a number of drawers0.all of
which must be of the same size and somewhat larger in number than there are riveting
places in a particular section of the plant. Each drawer should have a number, which
S '
refers to a particular riveting place. The drawer (Fig.108) has four compartmTATu.,
to have a maximum number of rivets of various sizes for particular applications
handy; but, as a rule, these should not exceed four.
The supply of rivets in the drawers is carried out in the following sequence:
135
I
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,
:??z
?
0000,
I.
r.-711:a sum r oz. caw
C
???
"7t"-..;
After checking on the requirements of each riveting place as to type, material,
'
._ sizes, and number of rivets needed, the_stockrolmnjuanagem_aorts_the_rivets_in the
drawers. He then distributes the filled drawers to the riveting places, making sure
that there will be enough rivets for one full shift. With this system, interruption
of work due to lack of rivets is eliminated.
136
STAT
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-
-4:74
I.
2
-14_-
16-
PART III_
ja316DSHOF RIVETING, FLQUIPMENT AND TOOLS USED
CHAPTER VII
CLASSIFICATION OF METHOW AND PROCEDURES IN RIVETING
1. Riveting Process
Depending on the method used for dim
)
2.7:12:1111 _
the procedures followed in riveting
practice may be grouped as A, B, C, and D processes.
24--
Riveting by the A process is characterized by the fact that the recesses in the
26__
materials to be joined are made by dimpling with a punch and die, so that the rivet
28_
34j
36_I
Fig.109 - Schematic of the Riveting Procedure by Process A
- Preliminary drilling of holes; b - Dimpling of recesses; c - Drilling of holes
, 40_1
to final dimensions; d - Fitting of rivets; e - Heading
4-4 ead fits into the' recess and is flush with the surface of the parts. The technical
- 46 procedure of riveting by the A process (Fig.109) consists of the following steps:
48 1. The planking is placed on the airframe, holes are drilled for holding tIsTAT
ssemblyin position, and the holding dev4ces are installed at 150 to 300 mm spacing.
52--4The tools used in these operations are drill presses or hand drills, clamping de-
/1:46 41/ZeZ
S\%' g1.N.N.NN
a)
c
oz.
TM'
K 3
ITTY
054__Tices-y-and-wrenches-for-tightening-theclapps.
561-----2les-are drilled-to preliminary size in the mating parts, using templates
1
33:7_
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-
, - -
_
.of
or. guide holes, either in a drill press or with hand drills.
3. The recesses are dimpled either separately in each part or simultaneously on
both mating parts by means of a punch and die, using a power press or a pneumatic
hammer.
4. The holes are again drilled to final dimensions, corresponding to the size
of rivets used.
5. Rivets are inserted in the dimpled recesses.
6. The riveting is performed by fitting the smooth surface of the punch and die
into a pneumatic hammer or into a suitable power press.
Fig.110 - Schematic of the Riveting Procedure by Process B
a - Drilling of holes; b - Insertion of rivets; c - Dimpling of recesses; d - Heading
Riveting by the B process is done 'by using the rivet head for dimpling the re-
cess under the' rivet head for flush riveting. The technical procedure of the B pro-
cess (Fig.110) consists of the following steps:
1. As in the A process, the skin is placed on the airframe, holes are drilled
for the clamping devices, and the holders are fixed in place.
2. Holes are drilled in the mating parts to a'size corresponding to the diameter
of the rivet, using templates, drill jigs, or the guide holes previously drilled in
one of the parts.
3. The rivets are inserted in the holes.
STAT
4. The recess is dimpled in the skin and airframe, using the rivet head itself;
in this operation the proper die and the smooth end of the punch are used, mounted
to the power, press or pneumatic hammer.
5. The riveting is done in a power press or with a pneumatic hammer.
138
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I
Riveting by the C process is done by forming the recess for the flush rivet heac
by a combination of two operations: dimpling of the recesses in the skin and coun-
tersinking of the recesses in the airframe. The technical procedure of riveting by
MUM ELIE2
a)
/ A
inswirr
vw
, A.A
\
Fig.111 - Schematic of the Riveting Procedure by Process C
a - Drilling the hole and countersinking the recess in the airframe; b - Placing the
skin on the airframe and drilling the holes in the skin; c - Inserting the rivet in
the hole; d - Dimpling the recess; e - Heading
the C process (Fig.111) consists of the following steps:
1. Holes are first drilled in the airframe and are then countersunk. In some
cases, the drilling and the countersinking is done at the same time.
2. The skin is placed on the airframe, holes are drilled for the holding de-
vices, and these are fixed in place.
3. Holes are drilled in the planking through the holes in the airframe.
4. The recesses in the skin are either dimpled by using the rivet head itself
or with the aid of a punch and die.
5. The rivets are inserted into the holes.
6. The riveting operation is performed.
Riveting by the D process is done by countersinking the recess for flush rivet-
ing in ,the planking. The technical procedure of riveting by the D process (Fig.112)
consists of the following steps:
1. The planking is placed on the airframe, holes are drilled for the holding
devices, and these are fixed in place.
2. Holes are drilled in the skin, following the guide holes in the airframe.
STAT
139
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3. The recesses for the rivet heads are countersunk in the planking.
4.,The rivets are inserted.
\
5. The riveting operation is performed.
_1 I
Flush riveting by the A, B, C, and D processes can be done in power presses or
with pneumatic hammers, using special jigs, tools, instruments, and equipment as
described below.
The data on establishing tolerance limits for riveting with the A, B, Cs and D
processes are given in Chapter V on "Methods of Forming Recesses".
Comparison of Characteristics of Riveting Processes
The basic characteristics determining the quality of work and the rate of pro-
duction by a given process are governed by the following factors:
a) Smoothness of surface of flush-riveted seam;
b) Strength of the joint;
c) Volume of work output.
Surface smoothness of riveted seams is characterized by the degree to which the
flush rivet heads protrude above the surface of the parts (planking).
To obtain the required degree of smoothness in flush-riveted seams when riveted
by any process, the geometry of the recess must be correlated to the geometry of the
WW1 ined?AI:
.N.M.1.% .N.W.Ir
a)
?ZIMP.1,11 I V./WV
'NOM" al ONNXII
tiff Mee"
306.N.N10:11.10NXVI
V
IMOIM
?
Fig.112 - Schematic of the Riveting Procedure by Process D
a - Drilling the holes; b - Countersinking the recesses; c - Insertion of rivetsTAT
d - Heading
flush-type rivets. This requirement can be met by using countersinking tools whioh
are so adjusted that the depth of the recess is correct, that carefully machined
140
Ite.ser...esteeorat.r.cmgereara=.
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---- ? 'r*-:? ? =,
6
punches and dies are used .for dimpling, that highly mechanized drilling and power
press equipment is available, and that the rivets are accurate.
Other conditions being equal, riveting by the D process gives better surface
smoothness than other methods. For this reason, in the production of structures with
relatively thick planking, this process is chiefly used in connection with flush
riveting. When using the A, B, or C process in which the recesses are formed by
dimpling, better results are obtained if the dimpling is done on power presses rather
than with pneumatic hammers. This is explained by the fact that, in the dimpling,
the harmer and the prop ray be unsteady and subject to change of relative position,
causing indentation marks on the skin surface and incorrect shape of the recess.
The strength of the joint is affected to a considerable degree by the riveting
process used.
Tests with static loads on joints have shown (Table 36) that specimens with
countersunk recesses, and riveted by the D process have a strength lower by 20% than
similar joints with dimpled recesses (A process), regardless of the combination of
'different materials in the seam.
' .The results of vibration tests [with n = 2000 cycles per minute, with the spec-
imens pre-tressed so that (7mean = O. 33 Gfaii (Fig.113), the basis of the tests being
equivalent to 107 cycles], have shown that joints made with countersunk recesses
(riveted by the D process) have a lower fatigue strength under all load conditions
4
than similar joints riveted by the A process. The decrease in strength in the fa-
tigue limit is 23%. For example, the yield point for joints made with dimpled re-
,
4 A
cesSes was owd = 6.2 kg/mm2, and for joints with countersunk recesses the yield
Point was owd = 4.8 kg/mm2.
In testing joints under repeated static loads, the number of load cycles re-STAT
sulting in failure of the joint by rupture, was taken as the reference point.
The ultimate load for the joint is
? a isiz. Kglinm
141
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-
where K is the load coefficient;
fail is the eltimate stress in kg/m- at which the joint fails.
The lower limit load represents 0.1 of the upper limit load, i.e.,
orain=---0.1 a /MX.
In the procedure of the above tests, the load coefficient was taken as 0.5. The
Table 36
Significance of Tensile Strength 6 in kg/mm2 of Joints in Relation to the
Riveting Process Used
?
Characteristic of the sheet stack
Riveting process
A
Manner of formin
g recesses
Countersinking
Dimpling with
punch and die
61 = 0.8 mm of MA8
62 = 1.0 mm of MA8
Rivet type ZU - 120? x 3 of AMg5
61 = 0. mm of MA8
62 = 1.0 mm of D16T -
Rivet type ZU - 120? x 3 of
Ame,5
11.25
11.40
13.35
13.14.5
STAT
(a = F ; where F is the cross-sectional area of the sheet over its width, in mm2)
142
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1?rs- , p
load cycle fluctuated within 8 -16 ayclei per minute.
- 2 The test results on Jointa, under repleated loading,__(Table.37) _indicate that .
" 4
6
10
-
1
-
?
19
?
14?
the strength of the joints, when riveted by the A process, is higher than in similar
????????I
16
24
in joints consisting of a combination of sheets of MA8 and D16AT materials. Here
_,the reduction in the joints riveted by the D process amounts to 35%.
in
For evaluating the strength of jots; riveted by the C process, a comparison
---
v.- le
I _
Fig.113 - Manner of Stressing in Teats with, (a) Vibration and (b) with
Repeated Static Loading
:points riveted by the D process. A particularly noticeable difference is observed
.was made with similar joints riveted by the D process, and with joints in which the
I
- rivets had protruding heads.
As indicated in Table 38, joints riveted by the C process have a
greater
strength in shear under static loads. In the C process, the recesses in the mating
parts are made by countersinking and by dimpling.
It is of interest that seams riveted by the C process are more rugged and de-
form less when stressed by static loads (Fig.114). For example, at a stress in the
, .
--seam of a = 10 kg/mm2, the slip in seams riveted by various processes is as follows:
a) 0.8% of the rivet diameter in seams riveted by the C process;
b) 4.3% of the rivet diameter in seams riveted by the D process;
c) 1.5% of the rivet diameter in seams with protruding rivet head.
In this manner, the slip in joints riveted by the D process is 4 - 6 times
-
--greater than in similar joints riveted by the C process.
-
143
STAT
, ?
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Tests with vibrational loads (at ashear = 0.33 afnii) show that the strength
is greater in joints riveted by the C process, in which the recesses are dimpled and
Table 37
Number of Repeated Loadings in Rupture Tests of Joints
Riveted by the A and D Processes
Riveting method
D
A
Load coefficient
Characteristics of the sheet stack
a
K = max = 0.5
?fail
amax = 5.6 k g/mm2
amax = 6.6 kg/mm2
amin = 0.6 kg/mm2
amin = 0.6 kg/mm2
5 8 mm of NA8
1 = 0 ?
5167
7828
52 = 1.0 mm of MA8
6825
6800
Rivets type ZU ? 1200 x 3 of ANg5
6818
6525
Average value
, 6270
7050
61 = 0.8 mm of NA8
6738
10951
62 = 1.0 mm of D16AT
8624
10774
Rivets type ZU ? 1200 x 3 of AMg5
6552
11115
Average value
7300
10950
countersunk, than in joints riveted by the D process, in which the recesses are
countersunk only (Fig.115). The reduction in strength in joints with countersunk
STAT
recesses is 30% and in joints with protruding rivet heads, 20%.
Thus, the strength of joints made by various riveting processes can be summar?
ized as follows:
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?:.lot-7,r1
_
1) The application of the riveting process C results in the greatest strength
when testing the joints by all described tests. 2) Next in order are joints riveted
Table 38
Strength of Riveted Joints as Related to the Riveting Process
Flush-Riveting Process
D
Countersinking
. C
Countersinking
and dimpling
Joints with
protruding
rivet heads
P in kg
1540
2260
1850
Strength
in kg/mm2
e
/1
17.7
100
26.0
146.7
21.3
120
Coefficient
of strength
= P
P
of the seam
P/
0.4
0.6
0.45
Note: 1. Sheets are of D16AT material; rivets of D18 material. 2. P is the
load in kg at which the sheet ruptures over its entire width.
by the A process with protruding rivet heads, resulting in almost the same strength .
joint. 3) Finally, joints riveted by the D process, in which the recesses are
' countersunk, have the least strength.
STAT
The output rate with these riveting processes depends not only on the particu-
lar process used but also on_the_degree of nechAni7ation available, such_as_equip,...
'ment, toolso_instruments4 and fixtures used for drilling, countersinking,_dimpling,-,
145_
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???
'.:as'.--Imivetingpropir.--:.For, example, other conations being equal, greater
uciisinAzay,bibtitineci by the rivet pro.Ceis A and by using_power pressesfqr '
18
24
4
_
?
?
?
?
?
,
.
?
,
?
f
. .
s
?
I
?
? I
''
?
V
?
;.
? ?
I
?
?
?
?
I
ft
.
:
?
Ilbol
?
10 2 '
. ,
?
?
?
1
,,,
?
0
'4
at
.
? ?
0 ?
? 4 li
?+ '
. .
i
ci- ? . .
A- . ??
P
d'17-( r- a) J
2 , 4 Il N N 20 ZI 24
FiA.114 - Effect of Riveting Process on the Slip in Joints
(Plates of.DI6AT; Rivets of D18)
a) F - Cross-sectional area of the sheet; b) Slip of the sheet in % of the
rivet diameter
dimpling, stationary drill presses for drilling and countersinking the recesses, and
power presses for group riveting. Then follows riveting by the 'D process; finally,
, ?the most laborious is the C process since it requires two operations: countersink-
ing and dimpling.
4:1
Methods of Forming the Clinched Rivet Heads
-
3?
I
Regardless of what particular method is used in flush-riveting operations, th(STAT
" -"heading at the tail end of the rivet shank is done with power presses or pneumatic
3.
rt,
4 -c
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- - - - - - -
-
? _I -
_?
When riveting with pneumatic hammers, depending from which side the hammer is
applied relative to the head of the rivet that fits into the recess, the operation
7151) is known either as direct or as reverse.
In the direct method, the blows of the hammer are directed on the shank end of
6
13
12
11
10
8
7
10 120
1
I
i
1
-Tr
--
...........
?MIN
IMO
latilll
Illis
up
1
II
hi. 1111111111
111111
111
0-
.111111116..
3y-Izo? .
A --.?
11111111
?RI
.
I
?
T-7-t-
- 4
Si.-
.111
al
I
liii
0 .10 4.10 810 10 2.10k 4J08.10410L . .
c)
Fig.115 - Effect of Process Used in Forming Recesses on the Fatigue Strength
of Joints (Sheets of D16AT, Rivets of D18; Tests Were
Carried Out at Gshear = 0.33 Gfail)
a) Without rupture; b) (F - is the cross-sectional area of the sheet);
c) Number of cycles to failure
the rivet, while a heavy prop is pressed against the flush rivet head (Fig.116).
Riveting by this method with flush-type rivets is carried out in the following se-
quence (Fig.117).
1. The rivet is fitted into the drilled hole and the countersunk recess.
2. A heavy prop support is placed against the flush rivet head.
3. A tightening device is installed on the side of the rivet shank, ththsTAT
squeezing the parts to be joined.
4. The capping tool which fits into the pneumatic hammer is placed in contact,
347
--
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Fig.116 ? Riveting by the Direct Method
Fig.117 ? Outline of Riveting Flush?Type Rivets by the Direct Method
a ? Drilling holes; b ? Countersinking recesses; c ? Inserting rivets;
d ? Squeezing sheets together; e ? Riveting
1) Prop; 2) Squeezing; 3) Blows; 4) Riveting punch
Fig.118 ? Bending of Rivet Shank
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with the protruding shank and the heading is done by pressing the lever which! ,
turns on the compressed air thst_pperates the hammer.
-characteristic disadvantage of this method of riveting is the tendency to
? - The reverse method, of riveting consists in directing the hammer blows on the
?
, .
40
`, ? head .of the flush-type rivet, so that heac.ing is produced by the transmitted blows
^ ? - 42_
of the shank against the prop (Fig.119).
44
The riveting of protruding heads is carried out by this method as follows:
46
1. The rivets are inserted in the drilled holes.
"2. The punch end of the pneumatic hammer is placed in
50-4
-Jhead, while a prop is placed against the outlet end of the
? ? 52_
" ? ? side.
54
56d
3. As pressure is applied on the staiting lever, the hammer blows fall on the
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?
- - - -
...J rivet head with the result that the end of the shank becomes upset as it impinges
..against the prop.
When rivets with flush-type heads are riveted by the reverse method,
are formed under the rivet heads (see Fig.112).
Characteristic disadvantages of
Fig.120 - Riveting Rivets with Pro-
truding Heads by the Reverse Method
recesses
riveting flush-type rivets by this Method are
as follows:
1. Occurrence of cavities in the
planking around some rivets: These cavi-
ties cause buckling of the surface of the
planking (Fig.121a).
2. Depressions over the surface of
the entire riveted seam (Fig.121b), which
is observed more generally on multiple row
seams with a short distance between the
a - Drilling holes; b - Inserting ri-
vets; c - Riveting; d - Riveted joint
1) Squeezing; 2) Blows; 3) Prop;
4) Clinched head
rows and between the rivets in the row, as
for example, along the rids, where butt
joints of the skin may occur, etc.
This is explained by the fact that
any blows directed on the rivet head are transmitted to the outer surface of the
planking, resulting in depressions. Such depressions are often observed in struc-
tures in which the airframe is not sufficiently rigid.
When riveting is done on power presses, the concept of udirectu and "reverse"
riveting methods does not exist, since then the number of operations and the quality
,of work no longer depends on the relative position of the working parts of the tools
with respect to the original and the clinched heads of the rivets.
An evaluation of the quality of joints, produced by various riveting methods, .
was made by subjecting them to static, vibrational, and repeated static loads. The
results of the tests on joints with static loads showed that there is some tendency
150
STAT
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toward an increase in strength (by 2 to 3%) w;:en the riveting is done in power
presses. Tests on similar joints with vibrational (Fig.122) and with repeated static
a)
Fig.121 - Characteristic -)efects in Riveting Flush-Type Rivets
by the Reverse 1:ethod
a - Cavities in the area of the rivetheads; b - Depressions in the
surface of the sl-in along the riveted seam
loads (Table 39), showed that the method used in riveting has no influence on the
strenEth of the joints when tested under such Joadina conditions. However, for
Table 39
Load Cycles to Failure in Tests on Joints Pror!uced with
Various Rivetinrr Eethods
(see Fig.122)
Riveting rethod
Load coefficient
K = emax
Gfail
0.7
0.5
rmax = 8'9 kg/nn2
cmin = 0.89 It/ mm2
Gmax = 6.h kj/mm2
?max= 0.64 1i:/mm2
Power press
Direct blow
Reverse blow
7700
7890
/780
29,700
26,380 STAT.
30,910
robe: 1. Sheets of V95AT; rivets of V65 material. 2. The load cycles shown
in the Tab]e, are the average of three tests
151
_
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smoothness of the outer surface and production output, preference should be given to
power-press riveting. The application of the direct riveting method can be consid-
ered rational only when there is n1 possibility of using power-press riveting. The
Ebar
6.5
6.0
5,5
5.0
4,5
? 4,01
mmi
0
I
I 3Y-90?i61
2111 4 10' 810'105 2W
c)
4 1005105107
Fig.122 - Effect of Riveting Method on the Fatigue Strength of Joints
(Sheets of V95ATI Rivets of V65; Test Carried Out at ushear
r tr Without rupture
? - Press riveting
A - Direct blows
o - Reverse blows
a) Sheets V95AT; b) (F is the cross-sectional area over the entire sheet
c) Number of ccles to rupture
= 0.33 Gfall)
?
application of the reverse method of riveting is permissible only where power-press
riveting or hammer riveting by the direct method is impossible.
Dimension of Clinched Rivet Heads
STAT
In ordinary riveting (with protruding rivet heads) as well as in flush riveting
(rivet heads flush with the surface), in the majority of cases the rivets are headed
to a flat shape, the dimensions of which are shown in Table 40.
152
4.
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,4
r4
c.tAt4,4*"-.-t
(f.
The lower limit for the diameter of the clinching head is s'et to preserve a
certain strength of the joint; the upper limit is set to minimize deformation of the
ble 40
Dimensions of Clinching Rivet Head, in mm
a) .
1'9 2,6
3
3,5
4
5
6
8
9,5
10
c)?
d)
e) ?
3,9
4,5
5,25
6
7,5
8,7
11,6
I13,8 14,5
+0,251
+0,3
+0,4
?0,5
+0,8
+1
1,1
1,2
1,4
1,6
2 2,41
3,2
3,81 4
a) Specified rivet diameter d; b) Sketch; c) Diameter of clinching head D;
d) Tolerance in D; e) Lowest tolerance of height h
joined parts in riveting.
At the established correlations of the rivet diameter, drill diameter, and
length of shank allowed for heading of the rivet, the outside diameter of the
clinched rivet head D.will be equal to 1.5 2.-0.1 of the diameter of the rivet shank,
D---=(1,5?0,1)d.
STAT
The above correlation applies to rivets with a diameter of 5 mm. For diameters
larger than 5 mm, the head is determined by the relation
D.(1,45?0,1)d.
The height of the head is set by the lower limit, which assures equal shear
strength of the head and bearing strength of the shank. Regardless of the rivet
diameter, the height of the head will be h = 0.4 d.
153
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The dimensions of the head are greatly influenced by the overall length of the
rivet, which depends on the grip of the parts being riveted and on the diameter of
the drilled hole, corresponding to the diameter of the rivet.
. In forming the rivet shank by upsetting, part of the material is. intended for
filling the clearance between the surface of the shank and the walls of the hole,
and another part for the heading.
The volume of the rivet shank required for filling the annular space between
the walls of the hole and the shank'is determined by the relation
v (d0 ? s,
4
where d is the specified diameter of the rivet;
do the greatest allowable diameter of the hole;
S is the thickness of the stack being riveted.
The volume of the rivet shank necessary for heading is determined by the re-
lation
72
V = ? 0h,
4 -
where D is the greatest allowable diameter of the clinching head of the rivet;
h is the smallest allowable height of the clinching head of the rivet.
Aside from the above relatiOns, other factors must be considered in calculating
the length of rivets.
Table 41 containe data on the selection of rivets, of lengths correspondiSTAT
the grip, of riveted parts and also to the diameter of the rivets. , The lengths shown
in this Table will give clinching heads of dimensions corresponding to those in
Table 40.
To determine the rivet length from Table 41, matching the corresponding grip
of the parts, a straightedge is placed on the divisions -of the scale of the nomogram
which indicates the grip; the figures in the columns at right angles which intersect
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:?
'6.Ye I ?
I VA
tx.446
laaf?MgIMIA,
the strairiltedge line then will give the length of the rivet for the correspondinr
rivet diameter.
For example, for riveting a.stack of sheets of a thickness of S = 8 mm, the
lengths of the rivets shoilld be as follows:
For d = 2.6 mm L = 12 mm
For d = 3.0 mm L = 13 mm
For d = 4.0 mm L = 14 mm
For d = 8.0 mm L = 17 nun
The tolerance for the rivet, length depends on their length (from ? 0.2 to
0.4 mm). A deviation of ? 0.2 applies to rivets whose length ,does not exceed
10 mm; a tolerance of ? 0.4 mm applies to rivets whose length does not exceed 30 mm.
If the length of the rivets is properly selected for any particular grip, the
holes will be properly filled, the head will be of the correct form, and the re-
quired strength of the joint will be met.
The riveting of stacks of great thickness with rivets of large diameter pre-
sents considerable difficulties. For the heading, relatively great forces are
needed, requiring special powerful equipment. Furthermore, during the process of
riveting with large-diameter rivets, the stack of sheets, is subject to considerable
deformation, distorting the original shape of the parts.
Rivets of a special type with centrally located holes in the shank end are used
for certain riveting operations, with the purpose of reducing the work. Data on the
design and dimensions of such rivets, together with the special tools requistmsre
given in Tables 42 and 43.
The force required for heading such rivets is considerably less than the force
required for heading ordinary rivets with solid shanks. The strength of such rivet
seams, based on static shear and tension tests, compares well with the strength of
joints rade With ordinary rivets having solid shanks.
.\
A distinctive feature of this riveting process lies in the fact that, after t2c
155
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!?., ?
.. .
11
Ps''''' .'
47:
4 6 S
'
.. - , . .. .
?
0
-
Table 41
Data for Selecting Proper Rivet Length for Various Diameters,
Depending on the Thickness of the Stack Being Riveted
d ai mimezzlizzaizastammiaman
2 28 3 3 5 4 6
ma ..??? inn Rim IMO ....
2 INI "I WMWill WM Ill
Mu iv. wiron. WI NMI
3 fas ma" Ma mill Ina Ma IP/III
4 inii111:111gini mar IF II IN
5
6- ifid sz V119 MEI Fa rpm
7 la raill.,.../lia 10,111?. Farina, ff/.1 m., ,. .1.11
8 viii a" um lug 2
9Ll ti..... mL.1 Mifa I fNik/l .1KL_..A. iawnloAE11us Wilaigaw
11 wrii mi Ill mil 11111ffillilltki
12 nomilffil rug ilit1111:1?Fu
13 iblila witiit1111Fillield griLi
14 WA la EPlita 'MOM
15win plait)en
f 7
16 IN SIMEIWIIIMIS
1 g
18
DDDQD303,
2
DD 82
,,,,, 28 30 rfl rn
21
n Mull 30
30 inglal
minim
JO21
36
23
24
25
26
27
8
29
30
31
2
3
34
35
6
37
156
STAT
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dom.
gz'Aik?
-
-
.4,;;;Astelss
-=?-rag-A7.
it, a
"B.O.
holes are drilled in the sheet stack, the edges of the hole are chamfered at the
spots ,where the rivet shank is Leaded (Fig.123). This prevents cracks and reduces
Table 42
Dimensions of Rivets and Dies for Heading, with Depressed Head
Ir/
2.3?50?
8
jr,
44V/
A)
C)
b)
16 I 20
22
24
It
dl
hi
K1
? 1,4
0,32
0,4
0,6
0,6
1,4
0,35
0,32
?1,j6
0,18
22,5
5
6,5
9,5
9,5
22,5
5,5
5
18,5
-3
2.8
6,5
8
12
12
28
7
6:5
23 ?
3,5
31
7
9
13
13
31
7,5
7
25,5
4
33,5
7,5
9;5
14,5
14,5
33,5
.8,5
7,5
29
4,5
a) Symbol; b) Dimension in terms of rivet diameter d; c) Dimension of rivet
and die; d) Rivet diameter d, in mm
STAT
the force required for riveting.
When the riveting is done properly, the rivets will fit snugly fit into the
holes in the sheet stack, while. the dimensions of the heads becomes as follows:
a) For a head with a. depression in the center (see Fig.123a);
D = 1.40 d
h = 0.35-d
-
157
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'se
?
b) For an annular head (see Fig.123b),
D = 1.51 d
h = 0.37 d
4. Fillinp of Holes with the Rivet Shank
The riveted joints in light-alloy structures are subject to high static and
considerable alternating stresses which may lead to premature loosening of their
Table 43
Dimensions of Rivets and Dies for the Formation of Annular Heads
a)
b)
c)
d)
16
-20
22
24
D
1,6
25,5
32
35
38,5
d1
h
' ,
?
?
4,5
9
4,5
12,5
5
- 14
5.5.
15
B
1,51
24
30
33
36
H
0,37
6 .
7,5
8
9
H1
0,31
5
6
7
7,5
R
0,37
?
6
7,5
8
9
c
?
1
?
1,5
1
1,5
K
0,31
5
q
7
7,5
STAT
a) Symbol; b) Dimension of rivet and die, in mm; c) Dimension in terms of
rivet diameter; d) Rivet diameter d, in mm
- joints and their destruction. For this reason, the extent to which the holes are
filled with the rivet shank in joints of light alloys is one of the fundamental con-
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ditions determininr, their strength. This basic requirement is met by the proper
relation of dimensions of the rivets and the corresponding holes, together with the
Fig.123 - Filling the Hole with the Rivet Shank
application of the proper method of cold-riveting.
A comparison of cold-riveting of light metals with hot-riveting of sheet iron
shows that the holes are filled better in the first case. Figure 124 gives compara-
Fig.124 - Filling of the Hole with the Rivet Shank
a - Cold-riveting of light alloys; b) Hot-riveting of sheet iron
1) Original rivet head; 2) Driven head
tive data. forillustrating the extent to which the holes are filled in cold ,and in
,hot riveting practice.
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111
? -.4*7-1;400,
In cold-riveting it is observed that not only is the loJe onr/Jetel- fj3],, ,
there is some increase in the diameter of the hole; i.e.,
cl,=(1,02-1,08)4
where de is the diameter of the rivet after riveting.
do is the diameter of the hole under the rivet.
In hot-riveting, the rivet shank does not completely
clearance exists between the rivet shank and the walls of
dc= (0,9-0:98)
fill the hole,
i.e., a
the hole; in that case,
The peculiarities noted are explained by the manner in which the rivet shank is
deformed. In cold-riveting, the hole starts first being filled because of the in-
crease in the shank diameter followed by the heading.
In riveting light alloys, the increase in the rivet-shank diameter is not uni-
form over the thickness of the stack. The shank acquires a conical shape of 2 - 5%
taper, with the apex of the cone in the direction of the original rivet head.
The increase in the shank diameter during riveting is accompanied by deforma-
tion and toughening of the sheet material, which is sufficiently significant to in-
crease the hardness.
Figure 125 gives a space diagram representing the hardness at different Points
of the joint. This diagram shows that the increase in hardness of the shank mater-
ial amounts to 3 ? 5%, while the hardness of the material in the upset head
35% over the original. The hardness increases evenly from one area to the next,
without skips, and without stress-concentration peaks which would cause premature
failure of the joint under load.
The nature of the distribution of hardness and of toughness remains alike, re-
gardless of the particular riveting method (whether by poWer press or hammering) or
of the type of rivets used (Fig.126). In the sheet area in contact with the rivet
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1 -
'shank, a certain cold-hardeninp: exists, which is evidence that the rivet is under
some tension. For this reason, when riveting parts of different materials or of the
same raterial but different thicknesses, the driven head should, if possible, be on
ffi.11.1.011.74.5f
I40
ao
100
eo
Fig.125 - Hardness of the Rivet and Sheet Material at Various Points of the
Joint (Press Riveting)
1) Sheets of D16T; 5.= 2.5.mm; S = 5 mm; ?) Rivet type ZU-120? x 5 of DlaP;
3) Cross section through B; JO Points of hardness measured along the axis x-x;
5) Cross section through 1; 6) Points of hardness measured along the axis 7-7
the side of the harder material; if the hardness is the same in the riveted parts,
then it should be on.the side of the thicker sheet.
It has been established that the dispersion of hardness in rivets when the
riveting is done in power presses is less than when done by hammering. Hammer ri-
veting does not ensure that the holes are completely filled throughout the thickness
.of the stack. It is especially difficult to obtain uniform filling of the holes
with hammer riveting of stacks having a thickness of S = (2.5 to 3)d, or more. In
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-4111Kalipm....
-414Pliiiriiiir ? ..iamr?
411111lNIIMPdmr'' deurAIN.~.41111111"wrAgasp441111mr
Ii i
? .41111141CAMpv
II
11
li i
1 11 I ,I
II I
I. II li
II
II I, II
II II II ii
1
1 ti II
I II
I II .11
IF 1 II
I II
Il-
1 II
II I!, II
I I
1)
e 17 34
2)
3)
Di117; N5 twn; S?51>mi
IF)
INN
b c e)fin,
7
:03
Fig.126 ? Hardness of the Rivet and the Sheet Material at Various Points of the
Joint (Hammer Riveting)
1) Cross section through e; 2) Points of hardness measured along the axis x?x; 3) Sheets of D16T;
cf)
6 = 2.5 mm; S = 5 rm;--14) Rivets of type 855115; 5) Hammer riveting; 6) Cross section through 0;
-
7) Points of hardness
measured along the axis y-y
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g
'cases where power press riveting is not possible, this often. requires the use of
bolts or of rivets having a high shear strenrth.
The
nents is
degree to which filling of the
illustrated diagranatically in
116'0
214
2120
2
2080
a) 2?6?
2
20
12.3
00 '04% ?
1380
108%
hole affects the strength of structural ele-
Fig.127. The diagram shows that the strength
of the strip in which the holes are filled
is 4 - 8% higher than the strength of simi-
lar strips in which the holes have no ri-
vets. This may be explained as follows:
During the riveting the rivet shank
increases in diameter, exerting a pressure
on the walls of the hole, deforming the
sheet first within the elastic limit and
then plastically beyond. Thus the rivet
shank in the hole is under stress whose
magnitude changes in proportion to the el-
ongation of the strips. For example, the
strength of a strip whose holes are corr7.
pletely filled with rivets having half-
round heads, is highe in comparison with
a similar strip in which the holes are also
filled but with rivets having a flat head.
The increase in strength of the strip where
STAT
the holes are filled with rivets having,
half-round heads is due to the greater
tightness (wedging against the walls of
hole) than that Which is present with flat heads.
The explanationgiven is confirmed by the results obtained on tests with vibra-
tional loads. The graphs in Fig.128 indicate that the strength of the strip in which
Fig.127 - Strength of Specimen
Strips as Related to the Degree
to 'Jhich the Holes Are Filled
1 - Strip with drilled holes;
2 - Strip with drilled holes exposed
to view; 3 - Strip with clenched ri-
vets (flat head) with filed-off heads;
4 - Strip with'clenched rivets;
5 - Strip with clenched rivets (half-
round heads) with filed-off heads;
6 - Strip with clenched rivets,
a) Load at rupture in kg; b) Factors
under investigation
the
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Fig.128 - Fatigue Strength of Strips with Riveted and with Open Holes
(Sheets of D16T; Rivets of D18 Material)
a) Humber of cycles to failure
PA'y
/600
......
.0...../1
\ ....,
\
N......??
N'No.
Zr
44
. 'Age
? ?? ? ? ?,????
a)
N
? 106?11,06?1 AO,
\
kl,
.. .. ?'.,
? " N
N7
is
4t
b)
?_ .
On ,IMID OEM
_ ?
_ ?. I I
. . ?
I ?
Fig.129 - Strength of Joints in Shear Tests as a, Function of the Hole Diameter
a) Hole diameter d; b) Rivets in shear; c) Rupture of sheets
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the hole is filled, is higher under all t7pes of loading than in a similar strip in
"which the holes are open.
All above statements indicate that, in order to obtain a high quality of work-
manship in riveted joints, the holes must be well filled by the rivet shank, which
is attained by the follcwing practice:
1) Use of press riveting and 'lamer riveting by the direct method;
2) Selection of correct rivet length, corresponding to the thiclmess of the
stack being riveted;
3) Adherence to correct technical riveting procedure (drilling, countersinking
and riveting proper).
It should be noted that in drilling the holes for rivets, the diameter of the
holes is in some cases too large, which ma: be due to improper grinding of the drill
50
40
JO
10
ID
?
a .
?
V,,,M,
WN
WW,
WMMMMMWC .___,
onfoi?A do .
N A 167
i - 0.8
? i
. 1
? - c) 11.= Of
?
d
? - ) d 3?? ow
u?
. e
I,
. A- "'I
11 I
t
FiE.130 Diagram of "Stress Warping - Slip" as a Function of Fit
a) Dowel pin and fixture of steel; b) Sheet D16T; c) Tightness dc/do = 1.06;
d) Clearance dc/d0 =. 0.81; e) Slip Al in of diameter of dowel pin (dc)
and to wobble of the chuck. The hole diameter in such cases is larger than the al-
lowed tolerances. It was proved by experimental investigations that the *static
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'strength of joints in shear increases to a certain amount as the diameter of the hold
is increased, and then drops abruptly (Fig.129). The filling of enlarged holes is
done at the expense of the material allowed in the shank for the formation of the
clenched head. As a result, the heading is not completed, which leads to premature
rrpture of the joint when the rivets are subjected to tension.
The degree to which the holes are filled has a considerable effect on the stress
in shear, which increases as the hole becomes more tightly filled (Fig.130).
A tir;htly filled hole increases the ultimate point of elastic deformation in
shearshear; thus, the elastic deformation causing slip in the joint is lowered un-
der static loads.
As seen from Fig.1300 in cases where dc/do = 1.06, which take place in ri-
veted joints, the ultimate stress a shear las a higher value, in which case the elas-
tic deformation is at a minimum value.
The last conditions further confirm the necessity of carr:-ing out the technical
process of rivetinp in such a manner that the holes in the stack of sheets are
tightly filled with the shanl of the rivet.
5. Flush Riveting from Two Sides
In certain structures, surface smoothness on both sides of the seam is required
i.e., from the side of the rivet and from the side of the clenched head. In such
cases, the rivet heads are made flush on both sides.
Depending on the construction of the assembled units, two-sided flush rivSTAT
is done as follows:
1) By countersinking recesses in the skin, under the rivet and under the
clenched head (Fig.131a)
- 2) Countersinking recesses in the airframe (in the thickest portion) and dim-
recesses in the skin for the rivet-clenched heads (Fig.131b)
3) Countersinking in the outer skin under the rivet and in the airframe under
166
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-
?
the
clenched head, and dimplinr recesses under the clenched head in the planking
while rivetinz (Fic.131c).
Rcr:ardlcss of the method used in making the rivets flush on both sides, drilling
of the rivet holes in the planking is done, in the case of the end stringer (air-
-frame), through the guide holes perpendicularly along its chord.
The countersinking of recesses under the rivets and clenched heads is done per-
Table 44
Dimensions of Holes in Rivet Shanks for Two-Sided Flush Riveting, in mm
Rivet diameter d
2.6
3.0
3.5
4.0
Hole diameter d1
2.3 '
2.7
3.2
3.7
Depth of hole h
0.7
1.0
pendicularly to the surface of the skin at each point (Fig.132). The pilot stem of
- the countersinking tool for this purpose is made short; with a spherical end.
Table 11.5
Allowance for Heading
STAT
Diameter of rivet, in mm
2.6
3.0
3.5
Allowance for the clenched
head, in mm
1.3
1.5
1.75
2.0 '
The countersink is made with a cutting tip whose shape depends on the thickness
of the sheet being countersunk and the type of rivets used, being as follows:
1) For countersinking recesses under the rivet, the angle of the cutting point
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L?
s1-1,faq?. ...:'-'f,Fr. -4'1 '.'" V.,'jLe ?-,4,
-f,,,e.,,54.04,4?1_,,,_taty?,r-ii;
-VAT*
'.-11 ?
\
bl cl
Fig.131 - Methods of Performing Two-Sided Flush Riveting
a - Countersinking recesses in the skin; b - Countersinking recesses in the air-
frame and dimpling recesses in the skin for the rivet and the clenched heads;
c - Countersinking of the outer skin for the rivet and of the airframe for the
clenched heads
Fig.132 - Aligning of the Countersink for Two-Sided Flush Riveting
a)
c)
04"
STAT
Fig.133 - Riveting of Skin Over the End Stringer with Alternate Position of
the Original and the Clenched Heads in the Countersunk Recesses of the Skin
a) Clenched head; b) End stringer; c) Section through a - a; d) Original head
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4 ,
is made equal to the angle of the rivet head;
2) For clenched heads in the case of thick plankings the cutting point of the
countersink is made to an angle of a = 900;
3) For clenched heads in the case of thin plankings the cutting point of the
countersink is made to an angle of a = 1200.
The rivets to be used may be of a type corresponding to specification 2022A50,
with the shanks finished in accordance with Table 44.
The allowance for the heading is assumed as equal to 0.8 of the rivet diameter;
in case rivets of the type listed in Table 04. are used, the allowance for the head-
ing is taken as outlined in Table 45.
The upper and lower plankings are joined along the stringer with one or two
rows of rivets in flush riveting. For this reason, the original and the clenched
rivet heads must be arranged along the lower and upper skin in a definite sequence,
as shown in Fig.133.
The riveting is performed by pneumatic hammers for the direct method, and the
reverse method is used in exceptional cases.
169
STAT
, F:
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_
CE:LPIM VIII
PRY.F.33 RIVETING, AIT:aLIARY TOOLS AND DIJIPI"EITT
3. General Considerations
Depending on their operating characteristics, tools used for riveting can be
subdivided into two classes; namely: hammer and press types.
The most widely used tools based on hammer action are hand-operated pneumatic
hammers. Their advantage consists in that they possess a wide ranEe of application
under most situations, particularly when the riveting is done in assembly fixtures.
Their disadvantage is that it is difficult to obtain a high degree of surface
smoothness, that their operation is noisy, and that the rate of productive output
is comparatively low.- A more precise method of rivetitnr: is to employ power-press
equipment, by means of,which most of present-day riveting of light-alloy structures
is done.
In this country, a great deal of work on press riveting and on the development
of technical processes of assembly by riveting was accomplished by the Enrineers
STAT
V.G.Corekhov, K.P.Kolobayev, L.I.Rokhlin, r.I.Slesarev, V.V.Bakulin,
and others.
A desirable characteristic of press riveting-is that the for:ration of the
clenched rivet head is done by uniform pressure on the rivet shank. The basic ad-
vantage of press riveting over hammer riveting are as follows:
1) Facilitating the work of riveters due to reduction in noise.
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-
2) Increase in production output, attained full utilization of the power of
the equipment, the adoption of group riveting procedure, and the elimination of
helpers.
3) Improvement in the quality of surface smoothness of the riveted parts.
4) Higher strength of the riveted joints, obtained by tighter and more uniform
filling of the holes by the rivet shank.
5) Greater uniformity in the quality of the riveted joints, since individual
peculiarities of the workmen are absent.
The advantages of press riveting, whether done singly or by the group method,
Table 46
Economic Aspects of Riveting with Pneumatic Hammers and of Single and
Group Riveting on Presses
Economic factors
Press group
riveting
Type of equipment
Single press
riveting
_
Pneumatic
hammer
Average output in a shift per
unit of equipment in number
of rivets
16,000
4000
3200
Approximate cost to rivet
1000 rivets, including power,
labor cost and amortization
of equipment, (in rubles)
, 4
.
12
' 13 .
Note: Computations are based on rivets of 4 mm diameter and a press with a
power of 25 tons;
STAT
over hammer riveting, as far as the economic technical aspects are concerned, are
illustrated in Table 46.
It is seen from the Table that, in single riveting, the production costs and
the output are approximately alike for hammer and for press riveting. Group rivet-
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,
411t,
ing on presses is considerable rore econoLical.
The practical experience of leading plants into which press riveting was intro-
duced confirm its great effectiveness. For example, with a press of 70 tons there
was a saving of 61 man-hours on one job of group riveting (planking of a wing) as
compared with hammer riveting. In another plant, as a result of changing over to
press riveting of 140 assembly units, the amount of labor involved was reduced to
one half.
The increase in the volume of work output with press riveting is
connected with
the necessity of separating major units into their constituent components, such as
minor units and panels, and the installation of more highly mechanized equipment,
tools, and instruments. If a methodical procedure in the handling of panels in
structures is developed, it is possible to bring up the percentage of press riveting
to 70 - 80%.
The advantages of press riveting show particularly in structures where, in addi-
tion to the requirements of higher strength of the riveted seams, greater surface
smoothness of the riveted joints is required. It has been established by investi-
gations that press riveting, either single or group, contributes' to the improvement
in.surface smoothness, as compared with hammer riveting. It is to be noted, how-
ever, that the quality of flush-riveted joints depends not only on the tools and
equipment used in riveting, but also on how well the geometry of the recesses agrees
with that of the rivets, on the quality of work in drilling and countersinking, and
on the qualifications of the workers. All of these factors have to be taken into
consideration. STAT
As compared with hammer riveting, press riveting results in considerably less
drawing of the material, and for this reason there is less distortion in the shape
of the joints which is the cause of cavities, swelling, indentations, and other de-
fects associated with hammer riveting.
When riveting with pneumatic hammers, the sheets are first squeezed together
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,
ana.acr..?=s,
before the riveting operation; due to the springiness of the material there may be
voids between the parts so that the frictional contact between the sheets is not
perfectly uniform, which may cause dis-
8000 tortion in the shape of the riveted
?i?
I.?.
d46,
r---
1-
I .._.,d..
-6mm
p-
1 ? dr5mm
. -----
1.1.5: :
d=4mm
cl.3mili
cl.'2,6mm
1
1
?- ,
mm
Fig.134 - Curves Showing the Rela-
tion Between the Applied Force and
the Diameter of Duralumin Rivets
with Flat Clenched Heads
a) Force in kg; b) Upset rivet por-
tion in mm
effected while the stack of sheets is
squeezed together firmly, with the ad-
joining parts in close contact and held
by greater frictional forces than in the
ease of hammer riveting.
While the work in press riveting is
facilitated by the methodical handling
of the constituent parts of major assem-
bly units, there are also other require-
ments the compliance with which may re-
quirements are the following:
1) The panels should preferably have similar curvatures and as far as possible
have only lon7itudinal eler:ents of rigidity that petmit free access to the place
.of riveting.
2) It is desirable that the riveted seams are made in accordance with staSTAT-
ized'practice throughout and that the number of different types and sizes of rivets
is held down to a minimum.
3) Rivets with flat headi in place of rivets with half-round heads should be
used for inside component members of the airframe.
4) .Components with concealed riveted joints should be limited in number as far
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t
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? as possible.
? Compliance with these requirements will enable to change over almost entirely
from hammer to press riveting of major and minor assembly units.
2. Classification of Riveting Presses
According to the manner of their utilization, riveting presses may be classed
as follows:
- 1) Stationary type for group riveting;
2) Stationar:- type for single riveting;
3) Portable type for single riveting.
The range of application of one type or another is determined by the volume of
riveting work, the dimensions of the assembled units, ease of access to the place
of riveting done, and by other structural and technical characteristics of the parts
being riveted.
Riveting presses may be classed according to the power requirement and the re-
* thod of utilization as follows:
1) Lever-type pneumatic;
2) Direct pneumatic;
3) Hydraulic;
4)
Pneumatic-hydraulic.
The operating principle of pneumatic lever-type presses consists in transmitting
the air pressure exerted on a piston head to the die through a system of levers,
with the result that a comparatively low force on the piston head is converted
STAT
with
larger force acting on the die.
On a majority of presses of this type, the increase in the force acting on the
die corresponds to the inherent requirements of the riveting work, the force being
greater when the heading is more pronounced, as indicated by the curves in Fig.134.
This also increases the efficiency of the press. Such presses are built with a
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1im
4
????
????
???
???
quidk return motion, which contributes to a greater work output by reducing the
machine operation time.
In terms of kinematics, the action of the most widely used lever-type pneumatic
presses is based on the principles A, B, or C.
Presses 0 eratinc*. Accordin? to Princi le A (Fig.135) are simple in design. The
mechanism of such presses consists of a system of levers of-the 1st or the 2nd
order. The following relations apply to
Fig.135 - Kinematic Diagram of the
Lever-Type Pneumatic Press, Opera-
ting on the Principle A
and the force Q, i.e.,
presses of this type:
1. At a constant force Q, exerted on
the piston head, the force P exerted on the,
die is directly proportional to the arms a
and b. Usually such presses are built to
fixed dimensions of the arms, so that there
is a direct relation between the stress P
D2d,
Q=
4
where p is the pressure of the available ,compressed air (5 kg/cm2);
nM is the mechanical efficiency, equal to 0.9 - 0.95;
D is the diameter of the pneumatic cylinder, in cm.
2. The motion of the die under the stress P and of the piston under the force Q
is inversely proportional to the arms a and b, whence the distance traveled by the
die is
"kt
a
STAT
where x is the travel of the piston in cm.
Figure 136 gives a curve for the relation between the force acting on the die
and its tr'avel. The travel is indicated by the straight line DC,-while the work
175.
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t*"
C.
?
performed by the die in one cycle of operation is indicated by the shape of the
ABCD. The curve AC represents the actual force required to upset the flat head in
duralumin rivets (see Fig.134). The cross-hatched triangle ABC is the part of use-
ful work utilized in upsetting the head, while the area of the triangle ADC repre-
sents the lost work.
The ratio of useful work performed to the total work done by the press is de-
2000B
MOO
12
80
6
I
Me V JV e ,z
r r dir
A
8.
49,5" 1 15 2 2,5 3 5 4
Fig.136 - Diagram of the Pressing Process on the Principle A
a) Stress PI in kg; b) Travel of set die, in mm
fined as the coefficient of efficiency ilk of the riveting process.
Usually presses operating on this principle have a comparatively low efficiency,
nk = 0.4 - 0.5. This is due to the fact that the force P acting on the set die,
which is equivalent to the force required for upsetting the rivet, acts during the
entire travel, while actually this force is needed only at the end of the stroke.
Presses Operated According to Principle B (Fig.137) have a more coMplicated
system of levers. The relationship between the force P on the die and the force Q
on the piston, in presses Operated according to principle B, is expressed mathemat-
.
ically by the formula
p-1(2,1-ftgatur
tgp- tga
The travel of the die is determined by
ya cos ?b cos 0.
176
STAT
sr/
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?
-
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The fOrce P on the die and its travel may be represented graphically by the
shape of curve (1) in Fig.138. The work performed by the press during the working
strohe is represented by the hatched area. The actual work needed for the rivet .
Fig.137 - Kinematic Diagram of Lever-
pe Pneumatic Presses Operating on
Principle B
3000
a) 2000
f000
Fig.138 - Diagram of the Stroke in Press
Riveting, Accordinp to Principle B
a) Force P in kg; b) Travel of die in mm
heading is represented by the cross-hatched area under the curve (2).
The coefficient of efficiency of the riveting process when presses of this type
are used, is nk = 0.5 - 0.6. In cases where such presses are utilized in riveting
Fig.139 - Kinematic Diagram of Lever-
Type Pneumatic Presses, Operating on
Principle C
30003/4
ai 2000
moo
b)
Fig.140 - Diagram of Press RivetilSTAT
According to Principle C
a) Force P in hg; b) Travel of set
die, in mm
work, using rivets of a smaller diameter than that for which the press is intended,
177
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trim:
???
?
will be still less, since'the area under the curve (2) is correspondingly reduced:
Presses Operated Accordinc, to Principle C (Fig.139) are in much wider use. The
relation between the force P and the force Q in presses operated in accordance with
principle C is expressed mathematically by the formula
P.1-2- (a x
b tg a /i )1
71s.
For practical calculations, the travel of the die can be determined from the
change in the angle of the lever by the formula
y = tg (cc? ,
where ainitial is the angle of the lever at the beginning of the stroke;
aend is angle of the lever at the end of the stroke.
The work diagram of press riveting according to the principle C is: represented
in Fig.11.0, where curve (1) shows the force P on the die as a function of its travel,
and curve (2) represents the force necess-
ary for upsetting duralumin rivets.
The coefficient of efficiency in ri-
veting with presses of group C is suffi-
ciently high, with nk = 0.7 - 0.8. -
The basic operating principle of
pneuMatic presses consists in utilizing
directly the energy of compressed air,
whose pressure is transmitted thro
F
Fig.141 - Simplified Power Diagram
for Pneumatic Press
In presses of this type
ugSTAT
series of pistons onto a plunger that holds
the die (Fig.141).
71,11411
P =Q Pnllbo
178
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..z.:.?f -4: Z' 4z, '
?
r
if
; ?
411.
'TO
'where Du is the diameter of the piston inside the cylinder, in cm;
p is the pressure of the compressed air in the system, in kg/cm2;
n is the number of pistons, in the cylinder.
The force acting on the set die is constant, and is independent of its travel.
The diagram of the process of press riveting is
the same as for presses operating according to
principle A (see Fig.136).
The operating principle of hydraulic
presses consists in the conversion of compara-
tively low oil pressure into high hydraulic '
pressure by passing it from the main oil line
through an intensifier, the pressure being 1;
transmitted through a cylinder in the press to
the set die. Figure 142 shows a simplified
Fig.142 - Simplified Kinematic
Diagram of the Hydraulic Press
diagram of the principle on which such presses operate. In the utilization of
presses in this group the relation between the forces P and Q is expressed mathemat-
ically by the formula
d2
Psle d2
In the diagram shown for the press, du and dn have constant values, and conse-
quently the force P is constant throughout the working stroke and is directly re-
lated to the pressure of the oil which goes from the main oil system into the
booster.
STAT
The same diagram applies alo to presses which combine pneumatic and hydraulic'
operation, having in the same unit pneumatic and hydraulic cylinders. A combination
of this sort makes it possible-to convert low compressed-air pressure into high
pressure in the hydraulic cylinder, which is transmitted through a mechanical system
to the set die of the press.
179
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C_1
-r _
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.4111W1-
Pneumatic, hydraulic, and Pneumatic-hydraulic presses may be used for riveting '
stacks of variable gage without re-adjustment for the thickness of the stack, for the
reason that such presses possess the characteristic that the force is the same, re-
Table 47
Force in kg, Required for the Formation of Flat Clenched Rivet Heads
Rivet.material
Diameter of rivet, in mm '
2.6
3
3.5
4
5
6
8
9
10
Aluminum alloys
D18, D16, and
V65
700
950
1500
2000
?
3000
5000
8000
10000
12500
Steel 15A
1000
1300
2200
2500
5000
6000
10000
13000
16000
Note: 1. The forces indicated are in round figures.
2. For the formation of half-round clenched rivet heads, the riveting forces
are 2.2 times greater than those given in this Table.
gardless of the position of the actuating power piston in the cylinder.
A very important cohdition that determines the suitability of a.press for a.
variety of riveting work, is its' maneuverability, which is determined by the size
and weight of the press.
Figure 143 shows comparative sizes of power cylinders used in pneumatic, hy-
draulic, and pneumatic-hydraulic presses, which develop a force on the die necessary
STAT
for riveting duralumin rivets of 6 mm in diameter. The diagram indicates that hy-
draulic presses are of smaller size as well as of lesser weight, This fact should
be given particular consideration in connection with any prbject involving portable
presses.
? Presses of the required capacity are selected on the basis of the force needed'
for formation of the clenched rivet head (Table 47).
180
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t?1
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t,;;
The design of riveting presses must fully meet the following basic reauirementsi
1) Provide a high-rate of production by increasing the number of working
strokes per unit time;
2) Permit operation of the press without re-adjustment whenever the thickness
of the stack or of the diameter of the rivet is changed;
3) Permit smooth travel of the plunger;
4) Ensure unhampered movement of the parts being riveted in the working area
of the press;
5) Permit operation of automatic straightening and relocation of panels and
assembly units of large size in group steps, (when using automatic straight-
ening and supporting devices);
6) Permit automatic riveting operation and servicing of the press b7 one
workman.
The domestic industry is manufacturing a series of riveting presses of original
STAT
Fig.1/0 - Comparative Sizes of Power Cylinder Units Developing
Pressures up to 6000 kg
a - Power unit of pneumatic presses; b - Power unit of hydraulic presses;
c - Power unit of pneumatic-hydraulic presses
design, Which, because of their high productivity and simplicity of maintenance, are
181
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'
I
G.
aaRtue.i.gt.
'used successfully for riveting of light alloy structures.
Presses for Group Riveting
A feature of presses for group riveting is that they have solid housings, which
- permits the application of high pressure by the plunger on the supporting prop
Fig.14.4 - Press Equipment for Group Riveting of Various Assembly
Units and Panels
through a group of rivets. According to their capacity they are subdivided into the
following types (Fig.144):
1. Presses of type KP-6021 for riveting panels of large size with a large
spread of the riveted seams;
2. Presses of type KP-501 and KP-503, for riveting components such as girders,
panels of intermediate size, and other assemblies;
3. Presses of types KP-403 and KP-405, for riveting comparatively small as-
sembly units such as ribs, frames, small girders, etc.
Technical characteristics of these presses arc given in Table 48.
STAT
182
E.?
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?-Z000 1-0061-00?1701-0-1-8dCl-V10 /,'O/O eseeiej ..104 panaiddv /Woo Pez!4!ue3 -1-led LI! Pe!PsseloaCI
Table !Le
Technical Characteristics of Presses for Group Riveting
a)
b)
c)
ci)
e)
f)
q)
h)
j)
k)
EEEEE
0
rim)
n)
43)
p)
E
E
EEE
,
ea
?11
16
CO
CO
N13-602
--
36
22
16
8
70000
3-74
200
450
1700
150
300
4600
2300
28000
.6700
3250
--.
KP-510
32
24
14
10
6
48000
10 -
100
--
--
--
1200
500
2260
'2670
690
--
KP-501A
28
15
10
7
4
3000012-20
35
430
1400
115
70
1050
600
2500
2360
930
0.13
KP-503
26
12
8
--
3
25000
5--14
16
500-
1400
175
125
1200
1000
2700
2450
700
0,22
111P-403
12
6
4
3,
1
1200012--24
16
490
1300
175
125
750
1000
1800
2400
500
0,13
KP-405
12
6
4
3
1
1200015--30
16
216
150
200
-
300
-590
2700
2450
700
0,05
Irl-vc-
tt. I
a
a.) Type of press; b) Number of duralumin rivets being riveted in one stroke of the press; c) Force on
plunger, in kg; d) Number of working strokes per minute; e) Working travel of the lower plunger, in Elm;
f) Greatest distance between the contact surfaces of the dies, in mm; g) Greatest distance from floor to
the center line of riveting; h) Auxiliary travel of the lower die to the center line of riveting, in ma;
1) Travel of upper die to center line of riveting, in mm; j) Opening ot press, in mm; k) Overall dimen-
sions, in mm; I) 04rhang,- 1; m).Jaw opening, h; n) Length; o) Height; p) Width; a)-Consumption of air
during one working cycle, in m3
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184
ho
?ri
04 CO
H
2 a)
ta)
5.
0
4_, 0
a)
0
0
?ri
43
cr) Pi
(i)
a)
7:$
4-4 cd
0
0
0 ?H
?ri 43
43
F-i
4) .4)
tt)
_ 0
0
C-)
? ;-t
I 0
cl
t.0
P7-1.r1
STAT
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?-Z000 1-0061-001?1701-0-1-8dCll-V10 ii'oio eseeiej -104 penalddV MOO PeZWUeS - 4-led u! PeWsseloaCI
r
???????;6-.
17
16
15
?
I 1111161111
17
41t,
SI
Ii
13
-16
(Fig.145 - continued)
1 - Housing;
2 - Lower plunger;
3 - Riveting tool;
4 - Hydraulic cylinders;
5 - Hydraulic drive;
6 - Riveter seat;
7 - Carriage;
8 - Detecting mechanism;
9 - AutoEatic mechanism for the
formation of the clenched
rivet heads;
10 - Electric motor;
11 - Oil reservoir;
12 - Upper plunger;
13 - Feeler gage;
- Pneumatic motor;
15 - Vertical rolls;,
16 - Control wheel;
17 - Roller. chains;
18 - Electro-pneumatic starting
device;
19 - Compressed air line;
20 - Automatic lubricator;
21.- Electric appliances;
22 - Tension device for the elec-
trical wiring of the upper
head;
3 - Control for the trolleys;
2k - Frame for bracinF the part
being riveted;
25 - Fart being riveted (a panel)
1
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_
Fig.146 - Kinematic Diagram of Press KP-602
1 - Drive for hoisting mechanisms; 2 - Control panel; 3 - Carriage drive; 1. - Cable for carriage;
5 - Hydraulic system; 6 - Lower die; 7 - Upper die; 8 - Drive for hoisting mechanism; 9 - Drive for hori-
zontal change of position of the heads
a) From ?1,e main line; b) From the valve of main manual control; c) From the main line
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?
Tress Kr-6o2.
_
The parts to be riveted are delivered to the press with the rivets installed,
and the following operations are performed on the press automatically:
1) The surface of the workpiece is aligned perpendicularly to the axis of the
rivet heads;
2) In successive steps, the upper and lower die blocks for group riveting
approach the workpiece, the stack is squeezed together, the clenched rivet
heads are formed, and the die blocks are returned to the original position;
3) The workpiece is conveyed for other group operations.
The operation of the IT-602 press is controlled by electric microswitches and
relays. The riveting of stacks of varying thickness, with rivets of different di-
areter, is performed without additional adjustment of the press.
The press (Figs.145 and 146) consists of the following components: the housing,
lower and upper riveting heads, mechanism for horizontal shifting of the rivet heads,
compressed air system, detecting mechanism, mechanism for the formation of the
clenched rivet heads, mechanism for automatic withdrawal of the plungers in the low-
er head, a tightening device, riveting tools and the supporting mechanism.
The housing (1) (see Fig.145) is the basic element of the press, on which are
mounted all the principal components and which serves at the same time as a support
for the carriage on which the parts to be riveted are laid out and positioned proper-
ly for riveting. The housing consists of a steel frame made of two vertical cast
steel colunns.united at the top and bottom by two girders. Each girder serves aq a
STAT
support and guide for the riveting heads.
There are openings in the sides of the columns for providing access to the
mechanisms and apparatus located inside the housing. The top of the housing is pro-
vided-with a removable cover. The foundation of the housing is below the floor
op. level.
The Lower Riveting. Head functions as the power unit for the formation of the
187
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r-
5
P
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,
-a,
'clenched rivet heads. The riveting head consists of the plunger (2), carrying the
riveting die block (3), four hydraulic cylinders (4), the hydraulic line (5) and a
control panel with a seat (6) for the operator. The entire mechanism of the lower
riveting head is mounted'on the carriage (7), which shifts it along guide rails in
the opening in the press from one column to another.
The plunger carries the detector mechanism (8) in guide grooves of rectangular
crops section for the riveting tool, the automatic mechanism (9) for heading the ri-
vets to the correct height, and an automatic mechanism for withdrawal of the plunger
from the workpiece.
The working and the return stroke of the plunger is effected by oil pressure
from two pumps operated by an electric motor (10). The oil reservoir (11) of the
hydraulic system has a capacity of 340 liters. All elements of the hydraulic system
are mounted on the carriage of the lower riveting head and are moved along with it.
The control panel is located in front of the riveter. The upper part of the
panel carries the operating controls of the press, such as pushbuttons for starting,
manual controls, and signal light.
The Upper Riveting Head with the upper riveting dies takes up the force exerted
by the lower riveting head. The plunger (12) of the upper head is lowered and raised
by means of a reversible pneumatic motor with the aid of a lead screw which trans-
mits the motion to the nut on the plunger. The pneumatic motor is.operated by two
. valves, providing rotation of the shaft of the motor to the right and to the left.
Four feelers (13) are fixed on the upper head, which serve to-start up the me-
chanism that levels the surfaces-of the parts being riveted before the rivetinSTAT
eration. A mechanism is located on the upper head for autonatic stopping of the
travel of the plunger. As the riveting tools come into contact with the surface of
the work being riveted and with the supporting props, the corresponding microswitches
are actuated. One micros-witch siops the plunger in its extreme upper position, while
another limits the withdrawal of the plunger during the interval when the work is
188
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-
- 'being lined up for another series of group riveting. The upper riveting die fits in-
to a groove in the plunger. The upper head is mounted on a trolley which moves a-
long the upper guide rails of the housing.
The Horizontal Alignment Mechanism for the rivet heads consists in the synchro-
nous alignment of the upper and lower riveting heads along the opening of the press.
This mechanism consists of a reversible pneumatic motor (14) installed on a bracket
on the right half of the press and the vertical shafts (15) with two sprockets (16),
which transmit the motion through a system of intermediate sprockets and roller
chains (17), and bring the upper and lower carriages of the riveting heads into a-
lignment.
The Pneumatic System of the Press provides raising and lowering of the upper
riveting head, drives the horizontal alignment mechanism for the rivet heads, and
operates the carriages and the four hoists for the automatic setting up and alignment
of parts to be riveted. The pneumatic system consists of seven reversible pneumatic
motors of the same type, electric and pneumatic starting controls (18), air supply
lines, and devices for operation and servicing of the pneumatic-system. The pneu-
matic system is supplied with compressed air at a pressure of 5 atm from the main
line. The air is supplied to the components of the horizontal alignment mechanism
for the rivet heads and to the carriages-through' pipes, and to the upper head and
, the hoists through fle4ble rubber hose.
The most important components of the pneumatic system are the drive of the up-
per head and the horizontal alignment mechanisms of the carriages. The piping sys-
tem includes an inlet valve, gage, settling tank, and an automatic lubricator. STAT
The special reversible pneumatic motor shown in Fig.147 is of the piston type
,and of flange construction. . It consists of a revolving cylinder block (1) and a
stationary distribution valve (2). The reciprocating. motion of the pistons is trans-
formed into rotary motion of the main shaft (3) by means of the rocking disk (4).
The planetary gear reducer (6) reduces the number of revolutions of the power take-
189
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($
C._
N?? P MOM 17 =? 7
qk f,,,mwt.4114.1111WOIVIOMMIVIVOAKIIIIVW,I,IANIVARMINIIV, I=I:z
ii- ---
II
.1"."
WIPLAOMIN
4c7
4. \ ?
6.117)61
-;111
I p p = n.
irip :
4z. .? ? I A s . ' 4 - .0. d din Mild.' d
I,
? N V di0 ,=.4.: ''''\\\\-' ' +=:,ii - lmE .--. 1 M qr.:740.- 1- - .?. ,
. =._,._.
mu ,,:r1r1.111
mhum& ws. N? ??11?411?440W 11.11 ' .1k111111
v , 11.4-11.11111,,,
o a .1N\ ' VAX 1 OW ob 4,degs
?
j 1A81-: 71)
?.: ,,... , , r ..
; ' 4
I II'
'011 ?
I .../ 1 li!1;4
,1/41??? t :....? ' s , . ss s V ;,/,......40:072 / V,
s 'Vs A \ \..,\.Z.g.., \ r 1115 ? A
"\Ai
:1:AWAIWIZOWZIWAW//,',WAI?WIWWWW.407/10.1"/"AlM/ZAIWeeo. ,. Z Pea4 ?AC*
Fig.147 - Reversible Pneumatic Motor
1 - Block with cylinders; 2 - Distributing valve; 3 - Main shaft;
4. - Rocking disk; 5 - Driven shaft; 6 - Planetary reducer
Fig.148 - Electro-Pneumatic
Starting Device
1 - Body; 2,3 - Valves; 4 - Electromagnet;
- Connecting fittings; 6 - Holes for
fastening the electro-pneumatic device
190
STAT
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ze-r,
?
Table 49
Outline of the Technical Process of Riveting on the Press KP-602 in the
Automatic Cycle
No. of
opera?
tion
Type of operation
Sketch
1
Initial position of the workpiece
The frame with the workpiece is
fastened on the hoist; feelers of
the press do not come in contact
with the work
111111
I pa:
I it
.
=Am
man.
ifilLrii
;Ma
51
I
,
?
2
,
Alignment of the workpiece
a) Workpiece brought to the feelers;
automatic alignment is begun
s
b) The workpiece is aligned
Impulse is given for lowering the
upper die block
niiIIIII
V'ml
emps
12:1
.lamm
"wwW.
?
main
.
'
III
V
? stI ill
Ill
III
1
? e
11111111l
.
is.-4111
I
STAT
.E.47. ? ?
dl .... ..
.eiva
.ii.
icor
.......
-1r
Mt III
iiiir
Elk
S.
191
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No. of
opera-
tion
Type of operation
Sketch
3
Lowering the upper die block
Tnavel of the upper die block ceases
as it comes in contact with the
workpiece; An impulse is given for
raising the lower die block
?
..- J11111,
.
INN !
Alimmm;
1V1NE;
II
szt_13L
pa
II
?
4
Raising the lower die block
a) Contact of the workpiece with the
web of the die block, starting up
the automatic heading mechanism
b) Contact of the rivet with the
surface of the die block, stopping
movement of the microswitch
c) Finish of the press operation,
impulse given for withdrawal of the
die blocks to the position set
during the adjustment
111
11111111
ill
4116,4
.....
1.16.rAmILI
Ili
Withdrawal of the die blocks from
the workpiece
.
Raising the upper and lowering the
lower die blocks, with an impulse
given at the end of the travel for
shifting the workpiece
Oa
.
1011111
-wog
Ailfi
f
o
st--m?lo
Nimilm?
0-0.qii
AM
?
STAT
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^
- ?
No. of
opera-
tion
.
Type of operation
Sketch
6
Shifting of the workpiece in group
riveting
a) Sliding the die block over the
profile of the workpiece produces
a displacement of the die block
with respect to the plunger, which
actuates a mechanism to bring later-
ally in riveting position another.
series of rivets
b) As the shifting of the workpiece
stops on the supporting props in
group riveting, no more rivets are
presented for riveting; the center
lines of the die and plunger meet;
an impulse is given for alignment
of the workpiece and for lowering
of the upper die
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110 off shaft. The reversal of rotation of the pneumatic motor is done by means of two
sets of electric-pneumatic starting devices.
The electromagnetic starting device (Fig.148) consists of the body (1), with
'a horizontally operated Valve (2) and a vertically operated valve. (3)., The elec-
tromagnet (4) is attached to the body, and when the current is on, the valve (3) is
lifted. The connection fittings (5) are screwed into the 'body and serve for tight-
ening the tube conduits. The electro -pneumatic starting device is attached to the
body of the press through the holes (6).
STAT
.The press has an automatic mechanism for heading the rivets to the required
height, regardless what the diameter of the rivet shank may be. This mechanism is
located in the upper part of the plunger of the lower riveting head. A description
of the construction and operation of this mechanism is carried out in the specifi-
cations for the power riveting unit KSA -403.
193 ?
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(71
II-, ? - . - - . -
The press operates according to the following three cycles:
1. The Automatic Cycle provides full automatic riveting 'of one seam, regardless
of its location on the workpiece. The riveting, the alignment of the work for group
riveting, and also the straightening of the parts is done automatically by pressing.
a button on the central control panel. The job of the operator in this case is to
oversee the operation of the press and the quality of the riveting work.
An outline of the technical process of riveting on the press KP -602 with the
automatic cycle is given in Table 49.
2. The' Semiautomatic Cycle is employed for riveting parts that do not have ex-
tensive seams and also in cases where the shape and the size of the piece does not
permit automatic alignment for group riveting. The riveting heads are brought into
proper position and withdrawn from it automatically in the semiautomatic cycle, but
the alignment of the work for group riveting is done by the operator by manipulating
the main manual control of the press.
3. The Manual Cycle is an auxiliary aid, arid is usually resorted to in adjus-
ting and checking the operation of the various mechanisms of the press while it is
being set up and tested. In that case, the riveting heads are brought into proper
position and withdrawn from it separately by pressing the proper button on the con-
trol panel. The manual control, is used for checking the mechanism which feeds and
'withdraws the parts to be riveted at the feelers of the press; to check the cor-
rectness of the stroke of the upper and lower riveting tools, and other operations.
Riveting itself is not permitted during the manual cycle, since the workpiece
may be damaged for the reason that, in the manual cycle, the alignment of the press
is not tied in with the riveting heads.
STAT
.The use of KP -602 preeses in combination with equipment for group drilling of
holes and countersinking recesses under the rivet heads reduces the labor consider-
ably, results in a better quality of riveting work, improves working conditians,
and leads to building up a high concept of organization in connection with assembly
194
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3,1,1
P.
-s
(-0
'work by the riveting method.
Lever-Moe Press KP-501A
The press KP-501A (see Fig.144) operates on the principle B, and has a charac-
teristic curve of operation similar to that shown in Fig.138. This press has an
automatic mechanism for withdrawal of the plunger by 70 mm, which permits to do ri-
veting work on components with protruding elements on their surface. The construc-
tion of the parts to which the riveting tools are attached is such that changing
and tightening of the upper and lower riveting die blocks can be done quickly, and
they may also be turned in a horizontal plane through 360? and set in position with
a graduated dial as a guide to an accuracy of 10. This permits to do riveting work
to join parts in a lengthwise as well as in a lateral direction. A kinematic dia-
gram of the operation of this press is shown in Fig.149.
The press consists of the following basic components: housing, lower plunger,
group of pistons, upper plunger, pneumatic system, lubricating systems, mechanisms
for the control of operation, and riveting tools.
The Housing is a rigid casting holding all mechanical parts of the press which
are accessible throti4h door openings. The lower plunger performs the riveting op-
eration, and its up-and-down motion is effected by the action of a group of pistons,
a pneumatic system, and a system of levers.
The Piston Group consists of two pistons inside cylinders which operate alter-
nately on the same connecting rod. The large piston is connected to the rod by
means of a spherical joint coupling and is actuated by air, supplied at the concave
part of the coupling. The maximum stroke of the lower plunger, equal to 35 inm/S.!CAT
regulated by the change in the stroke of the large cylinder, using a worm gear pair.
The Upper Plunger functions as supporting prop in riveting. Its up-and-down
stroke within the limits of 95 mm is effected by means of a nut which can be moved
by hand, using a hand wheel or operated by the pneumatic drive. The operation by
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'v4 7
-
ets
hand is used in setting up of the upper tools for a particular thickness of the
stack. Regulation is effected by means of a dial with a graduated scale. Automatic
shifting of the upper plunger comprises an overall distance of 70 mm, while in the
case of manual adjustment for thickness of the stack, the distance is within the
limits of 25 mm.
The drive for the upper plunger consists of a pneumatic cylinder block with
three pistons. One of the pistons marries a rack coupled with a gear whose purpose
is to shift the upper plunger by means of a chain and sprocket drive.
The Pneumatic System of the press consists of a mechanism for distribution of
the compressed air, and is composed of six valves for the air cylinders and a start-
ing valve, an air intake for stabilizing the air pressure distributed to the working
parts and acting as an oil separator, as well as an automatic lubricator for injec-
ting atomized oil into the air lines, to ensure proper operation of pneumatically
operated machinery.
The Oil System consists of a pneumatic pump which sucks oil from the oil res-
ervoir through a filter located within it, and supplies oil under pressure to the
oil pipe system.
The Operating Controls of the press are mounted on a separate portable panel.
The control panel contains, in suitable position, manual controls, starting and
stopping switches, and a pressure gage. The lower part-of the column, which holds
the panel, carries a foot pedal in a conveniently located place for foot operation
of the press. Flexible hoses connected with the manometers and 'valves, deliver
compressed air to the press mechanism.
The operation of the pressis indicated in the kinematic diagram (see FigSTAT.
Before the parts to be riveted are placed in the press for group riveting be-
tween the dies, the upper and lower plungers must be retracted to their extreme up-
per and lower positions. Valves (1) and (2) located on the control panel and shown
in the diagram, are used for this purpose.
196 1
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.?
Compressed air from the main line goes into the oil separator and from there
through the receiver and the automatic oiler, over the piping (3) and the valve (1),
via the valves (4) and (5) and the piping (6) into the chamber of the cylinder of
the control device. This causes the piston to which a rack is attached to move to
the extreme right position, with the motion transmitted by a chain drive turning
a nut which shifts the position of the upper plunger upward.
At the same time air is supplied through the piping (7), (8), and (9) into the
chamber in which the rod is connected to the working piston, with the result that
the sleeve with the spring is moved to the right, thus releasing the balls. The
rod moves to the right and carries the lower plunger to its extreme low position.
While in this position, the parts to be riveted are inserted in the opening of the
press, and by means of valve (1) the closing in of the plungers takes place i.e.,
the upper plunger is lowered and the lower plunger raised (in this case, the valve
(1) is in the "forward" position).
The air from the uncoupling chamber of the rod and from the exhaust chamber
(110 operating the withdrawal of the tool is exhausted to the atmosphere through the
valve (1). At the same time, air from the pipe (3) through the valve (1) and the
pipes (10) and (11) enters the chamber which regulates the preliminary position of
the tool and shifts the piston with the rack to the left, thus causing the upper
plunger to move downward. Simultaneously, through the piping (10), the upper out-
let of the valve (12), and the piping (13) air enters the chamber for shifting the
tool forward, with the result that the rod is shifted toward the left, permitting
entrY of the ball into its groove.
The air from the chamber, shifting the tool forward, enters the valve (12)
STAT
through the piping (14), causing a downward displacement of the valve; this con- .
nects the inlet chamber, which shifts the tool of the lower cylinder forward, with
the atmosphere; a connection is also made between the compressed-air piping (10)
and the starting valve (15).
, ? ?
197
'7,
ft
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? -
(co
Fig.14.9 - Kinematic Diagram of Press KP-501A for Group Riveting
1, 2, 27 - Valves; 3, 6 - 11, 13, 14, 17, 18, 20, 21, 23 - 26, 28, 29 -.Pipe-
lines; 4, 5, 12, 16, 19, 22 - Valves; 15 - Starting valve
a) Sprocket gear; b) Exhaust chamber for retraction of tool at each working STAT
stroke; c) Exhaust chamber for complete retraction of tool; d) Inlet chamber for
shifting tool forward at each working stroke; e) Chamber for shifting tool to a
preliminary position; f) Motorcycle chain; g) Drive for upper plunger; h) Coun-
terweight; i) Control panel; j) Upper plunger; k) Riveting tool; 1) Tool holder;
m) Lower plunger; n) Pneumatic system; o) Lubricating system; p) Piston group;
q) Uncoupling chamber; 0 Reverse stroke chamber; s) Chamber for tool retraction;
t) Chamber for shifting tool forward; u) Automatic oiler; v) Receiver; w) Coke;
x) Chamber for working stroke; y) From the main line; z) Control; aa) Felt
r
198
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Ig
t. A
.Fig.150 ? Power Riveting Unit KSA ?403
1 ? Plunger; 2 ? Piston block; 3 - Reversible pneumatic motor; 4 - Clutch; STAT
5,6 ? Gear wheels; 7 - Threaded nut; 8 ? Piston; 9 - Dial; 10,21' ? Coupling
rods; 11,24 ? Levers; 12,15,26,27 ? Microswitches; 13 ? Punch; -14 ? Pickup;
16,18,19 ? Bushings; 17,20 ? Springs; 22,25 ? Push rods; 23 ? Stud
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In this position, the press is ready for regular riveting.
To carry out group riveting, pressure is applied to the pedal, thus opening the
valve (15) and permitting air to flow through the outlet opening in valve (16) into
the piping (17) and thence, through the channels in the rod of the upper cylinder,
into the chamber which controls the forward travel of the tool.
The piston with the rack is shifted to the left, and the upper cylinder is low-
ered by 7 mm by means of chain and nut. As sufficient air pressure is built up in
the piping (17) for forcing out the check ball in the slide valve (16), the latter
is shifted downward. The compressed air in the piping (18) enters the upper opening
of the valve (19), goes through the piping (20) and then into the chamber controlling
the working stroke, thereby shifting the working piston to the extreme left position
and at the same tine shifting the lower plunger upward.
When sufficient air pressure, with reference to the line pressure, is built up
in the chamber of the working stroke, the air goes through the piping (21) into the
valve (22), shifting it to the right; this provides a supply of compressed air to
the upper valve surface, shifting the latter downward, with the result that the
chamber of the working stroke becomes open to the atmosphere. Compressed air through
the piping (23), (24) and (25) enters into the reverse stroke chamber, returning the
working piston to its original position. At the same time; through the piping (26)
air enters into the chamber controlling retraction of the tool, at the same time
moving the piston with the rack to the right and shifting the upper plunger upward
by 7 mm.
If it becomes necessary to hold the lower plunger in its extreme upper posi-
tionl(as in setting up the press), the cock (27) must be set into the position STAT
"setting up". In that case, depressing the pedal of the press connected with the
piping (28), opposes the shifting of valve (22) to the right for the duration of the
automatic cycle.
When retraction of both plungers is not required, as in the case of riveting
200
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?,.
panels with sMall and tough protruding elements), it is possible to retract either
the upper or the lower plunger only. For this, the cock (2) is placed in the posi-
tion "upper" lor the position "lower". This causes the valve (5) to shift to the ex-
-
V_
treme left (closing the pipeline (7) and permitting only the upper plunger to oper-
ate) or to the extreme right position (closing the pipeline (29) and permitting only
the lower plunger to operate).
The compressed air is supplied to the operating mechanism in a definite sequence
over butterfly valves.
The prels is started for operation in the following manner: The main valve is
opened for admission of compressed air to the control elements. When the pressure
gage on the control panel indicates an air pressure not lower than J. atm the handle
of the cock (1) is turned to the position "supply". In that position, the upper
plunger descends and the lower plunger rises. To avoid a deviation of the lower
plunger from its extreme upper position on application of pressure to the pedal, the
cock (27) must be turned to "setting up".
Next, the press is adjusted for the thickness of the stack being riveted and to
the height of the clenched heads, by means of the hand-wheel which controls the
raising or lowering of the upper plunger. The distance to which the plunger is
raised or lowered is determined by the indications on a dial with 0.2 mm divisions.
One full-scale deflection 'of the pointer over the dial represent 12 mm.
Pres1 s KP-- l-/0aF.__2?ndicP-/ 0
,
These pneumatic presses (see Fig.1)4) represent a particular group of semiauto-
matic presses for group riveting of components of the type of girders, medium-si
STAT
panels, etc. In design, these presses consist essentially of a combination of sepa-
_
rate self-contained assembled units; namely, a power riveting unit, ,a support unit,
automatic control elements, and other components. The use of.such self-contained ?
units permits the erection of special-purpose presses in an economical manner.
201
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? At4.?=t,
Power Riveting Unit KSA-403
This unit (Fig.150)
develops a force required for the working stroke in rivet-
ing. The working stroke of the plunger
Fig.151 - Press '0-405 for
-Group Riveting
1 - C-frame; .2 - Pedestal; 3 - Plunger;
4 - Tool holders; 5- Dies; 6 - Oper-
ating pedal; 7 7 Electric device with
_pneumatic motor; 8 - Mechanism for set-
ting the retraction distance of plun-
ger;, 9 - Cock for air inlet; 10 - Air
cleaner; 11 - Automatic oiler;
12 - Piping for supply of air from the
compressedrair system
(14) on the microswitch (15) located on
controls the stopping of the
(1) is produced from the piston block (2),
while the auxiliary stroke is effected by
the reversible pneumatic motor (3) through
the clutch M, the gears (5) and (6) and
the threaded nut (7), which transmits the
motion to the plunger. The travel of the
plunger is 16 mm. The return of the pis-
ton block (2) is effected by means of the
piston (8).
The distance of retraction of the
lower die block from the
ed is regulated by means
On turning the dial, the
part being rivet-
of the dial (9).
cam at its lower
part acts on the lever (11) through the
ball-ahd rod (10), which in turn transmits
an impulse to the microswitch (12). The
microswitch actuates the electro-pneumatic
starting device, which controls the motion
of the pneumatic motor of the power unit.
The operation of the mechanism for
rivet heading to the specified height pro-
STAT
ceeds as follows: As the plunger is
raised upward, the pressure platen of the
punch (13) act through the pickup device
the body of the power unit. The microswitch
pneumatic motor and turns on the power during the work-
202
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-
s
ing stroke of the plunger from the piston block. As the plunger is in motion, the
bushing (16) makes up to three revolutions before the die comes in contact with the
shank of the rivet. On further movement of the plunger, the clearance is better de-
fined, with the result that the sizing (17) becomes compressed. The bushing (18) is
locked under the action of the bushing (19) and the spring (20), and' heading of the
rivets is done as the plunger moves farther.
The deformation of the rivet shank continues until the time when rod (21),en-
trained by the plunger, no longer is in contact with the beveled face of the bushing
(16). This causes the rod (21) to stop and hold down the push rod (22), which has a
drilled recess into which the stud (23) is 'fitted. On further upward movement of
the plunger, the stud (23) is forced out by the bevel edge on the push rod (22) and
thus actuates the lever (24). The lever, over the push rod (25), trips the micro-
switch (26) which prevents further raising of the plunger and starts the rapid with-
drawal of the plunger from the workpiece. At the same time, under the action of the
piston (8) which controls the reverse stroke, the piston block is returned to its
41, original position, and all the operating Chambers in the block are opened for ex-
haust to the atmosphere.
The press KP-405 (Fig.151) incorporates the basic operating principles of the
described power unit KSA-403. In the design of this press, provision was made for
changing the C-shaped frame from one size of opening to another, to comply with the
riveting specifications for parts which require a large overhang of the frame.
Presses of the type KP-4.03 and KP -503 utilize the power units KSA-403 and
KSA-503, which do not much differ in design; in addition they comprise the support-
? ing units KPA -403 and KPA -503. These supporting units (KPA) absorb the riveting
STAT
forces and make it possible to shift the upper die blocks vertically within the
limits of the available space to the workpiece, thus facilitating the adjustment of
the upper parts of the press.
it. The presses KP -403 and KP -503 operate on the automatic cycle, which consists in
203
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