TECHNOLOGY OF AVIATION INSTRUMENT CONSTRUCTION

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• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP81-01043R002700120001-4
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 136
• Document Creation Date: December 23, 2016
• Document Release Date: January 28, 2014
• Sequence Number: 1
• Publication Date: October 9, 1958
• Content Type: REPORT

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I 1
TECHNOLOGY OF AVIATION INSTRUMENT CONSTRUCTION
(TEKHNOLOG I YA AV I ATS I ONNOGO PRI BOROSTROEN IYA)
BY A. N. GAVRILOV
SOURCE: OBORONGIZ, 1951
PAGES 9-25; 69-74; 190-211; 341-348
.11
?
STAT
UNEDITED AND UNPREPARED FOR PUBLICATION
PREPARED BY
TECHNICAL DOCUMENTS LIAISON OFFICE
MCLTD
WR1GHT-PA1TERSON AIR FORCE BASE, OHIO
STAT
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STAT
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--
1
1
Table .of Contents
6 Chapter_11___Precision_in..Machining
?1
6? 1. General Statements 1
-n
10-1 2. Sources of Production Errors in Machining 2
1971i
3. Methods of Precision Analysis and Computation of the
Technological Processes ' 5
14
__ 4. Conditions and Probabilities of Obtaining Set
16-- Tolerances in the Production of Parts 18
18_- _._
Bibliography 1 26
20_1 1
Chapter V Allowances and Intermediate Dimensions 27
--22_.. 1.
29__
1. General Principles 27
24? I
2. Method for Determining the Amount of Allowance 28
6 261 I
-- 3. Calculation of Intermediate Dimensions 31
.
28-_,
? Bibliography g 1 37
30__
32...1 Chapter XI Parts of Tooth Gearings , 311
341 1. General Principles 38
36d!
1
2. Technology of Executing Typical Parts of Tooth Gearings 41
!
38--3. Analysis for Accuracy in the Production of Toothed
i
40 Gearings 62
1] I
1 Bibliography 69
42___i
I
44-1 Chapter XVIII Technology for the Production of Speciil Parts
46 and Assemb3,y of Gyroscopic Instruments 70
=1
i
_J
48_1 1. General Principles 70
50 2. Characteristics of Some Gyroscopic Instruments 73
__
. 3. Axles and Cups of Bearings 72
52-1
---;
54 4. Rotors so
t
5. The Frames of the Gimbals 85
STAT
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14_
16 ?
_
18 _
20_
22_
24--
?
26.-
28
I
30_
32
34
36
3
40
42
44
46
6.
AsseMbly of_the_Bearing Unit_ _
92
7.
Assembly of the Gyroscope Unit
100
8.
Assembl,y of the Damping Unit 115
9.
Assembly of Gyroscopic Instruments 117
48
50
5
54
56.3
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PRECISION IN MACHINING
16--
18? ?
1. General Statements
20_
22:: Precision in machining is understood to mean the degree of correspondence of
24_ the manufactured part to the theoretical ?iensions, form, and mechanical and physi-
26_ cal properties.
28-- In cases of individual production, dimensional stability and precision of form
It
30_ is obtained by the trial-ass method, and in cases of series and mass production by
32_ the method of automatically obtaining measurements.
34_ In machining a part by the trial-pass method, the worker adjusts the tool "to
36_ dimension" after each pass, and then proceeds to the machining of a snail section of
38-- the part. The dimension obtained is checked, and after this the entire surface is
40_ machined. In precision work, the tool is *adjusted to dimension" after two or three
42_ trial passes. The trial-pass method is not very productive; high4 skilled worn
44 are required for the machining of parts bi this method which, for this reason, is
46 used chiefly in cases of individual produlion.
48 In work done by the automatic method, the necessary dimensions of the part are
50 obtained by a preliminary adjusting of the machine (preliminary tooling), or by the
5 use of suitable tools and devices. As examples of the automatic obtainment of di-
54 sh-inimg-on-automatio-machines-u-on-turret-Iathe
--Work-done-by-the method-of-automaticaa7-ob
L.
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11.6???????....1?16....1
??????????.1..11111111
mensions can be carried out by less skiflid workmen. The use of the automatic meth-
? s the technologist_to_make a mor careful Anal sis of_the canses of Arrora_
in machining, and eonsequently to make a ore careful calculation of the precision
of the technological processes.
10-, . Sources of Production Errors in MaChininic
Discrepancies between the dimensions
14__
its theoretical dimensions and form, which are due to production-technology causes,
16
are referred to as production errors; all discrepancies between the actual techno-
18
logical process and the ideal technologic4l process are referred to as primary
20
errors.
22
Let us examine the basic primary errors.
24 il,2_3eon
Theoreticalerrorsduetotleapproximatemacdiaam. These
and form of the part under machining and
26
28
30
32
errors occur as a result of the conscious
se of an approximate machining diagram:
instead of an exact one, or as a result o the conscious use of a tool with an api.
proximate profile. As an example of theoretical errors we may cite the cutting of
thread on a screw-cutting lathe without the necessary change-gearwheels. As we
34
know, in such a case these gear wheels are replaced by others which permit only the
36
approximate obtainment of the set pitch on the part being threaded. As a second am-
3
ample we may use the cutting of teeth by the generating method. As a result of the
40
finite number of cutting edges, the process of profile forming is interrupted, mmi
42
--for this reason, instead of an involute profile on the gear wheel which is being cut
me obtain a broken straight line which bends into an involute curve. The use of an
46=1 --approximate machining diagram may be justified only in cases where the technological
48
50
ocess is simplified and the set precision is obtained.
Inaccuracies in equipment. Machines n actual use have a lower degree of pre-
,
5
ision in their work as a result of wear. However the degree of inaccuracy in the
% 54
--execution of the machine gives no indication of its influence on the accuracy of the
56
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bitted part. To solve this problem, aTe cial calculation mast be made for each
?Icy of the machine restate in a skew in thei axis of the tap relative to the axis of
__the aperture being threaded, and this, as the analytical calculations by II.N.Udhakov
10 --
-
12 --
e_CaSe ?
For example, in the cutting of thread on a thread-cutting machine, the inaccur
(HAI) have shown, leads to oval. threads.
Inaccuracies in the cutting tool and attachments.
or a profile tool, precision in machining Ls directly dependent upon the precision
of the cutting instrument. Precision in the execution of a nonmeasuring tool (cy
In working with a measuring
16-
18
__drical rrrlling cutters, pass cutters, etc.) has an indirect effect upon precision in
20__
machining. For =ample, when a vri 1 ling cutter is ground incorrectly, its teeth will
22__
--take off a chip of unequal thickness, and this will lead to a change in dimensions
24
and a distortion of the form of the suet+
26
Errors in the execution of attachmentb also have an effect upon precision in
28
30
32
36__
hining. As an example we may use the error which occurs in boring as a result of
eatiraci -in--the- desiol. of.the4ig bearings,, as a result of the distance between th
s of these bearings, and as a result of: other causes.
Wear of the tool. In the process of frorking? a tool wears out. We may estimat
oughly that the wear of a tool is in proportion to the length of the path traveled
the tool blade. Wear also depends upon the material and the geometry of the tool
3
--Avon the material under machining, etc.
42
Deformation of the elastic system machine Part?Tool*. Under the action of the
44
orce of cutting and other forces brought to bear on the machine,-part?tool system, a
46
--deformation
481
50
_.jiere
rigid.
52-
the part
is produced in it; as a result of this, the form and dimensions obtained
are different from those which might have been obtained if the system
564?itigiditralra-techn?1?
54 gical-factor-is-examined-ixrdetatl-in-tha-paper-by-Prof.
????? ??? ? to ? j.kwp ? 4?A AL:2,11_12114111L ?
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4_1is
normal for the surface which is being machined) to the displacement y of the tool
6 I
!blade relative to the part, this displace ent being reckoned in the same direction:
????????=???????INIMUMMIE?611C.211.11.i.. 111022.,=.123-
Th omie rigidity j of the elastic system the usual name for the ratio of the c
ponent_nf_the_force_of cutting_23gthis_component_being_directed-according-to-3dast?
l
12
The rigidity of an elastic system depends upon the rigidity of all its links.
_The rigidity of the part under machining jay in many cases be determined by: calcula,
14
16-1 tions on the basis of the formulas for the material strength. For example, to deter
18
mine the rigidity of a cylinder which is I
__ er center machiming, Prof. A.P.Sokolov-
20
22
24
26
, 28
30
32
34
skiy recommends using the formula for the flexure of a beam freely supported at two
ends.
36 Fig.]. - Types of Load Curves
3
40
Fig.2
The rigidity of the joints of a machine is determined by experimenting. To do
this, the joint of the machine is subjected to a definite force, corresponding in dir.
42
ection and point of application to the stress exerted under the normal operating
44
--conditions .of the machine, and then the deformation of the joint in the direction
46driormil for the surface being machined is measured. On the basis of the data 0)-
48
50
5
4 54
56
ained, the dependence P = f(y) is set up, where P is the load. The experiment -
haws that the rigidity characteristics may differ (Fig.1). In some cases, j =
conat and the characteristic is rectilinear; in other cases, the rigidity falls as
he load is increased (see curve a); finnliy, in still other cases, the rigidity may
STAT
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---,increase with an increase in load (curve ). The total effect of the gaps is char-
acterizecLby the_Mreak,of_the_characteristim", i.e.-,--bythe i1 'placTflflt of the
4?
joint, determined at the smallest points of the diagram under a load equal to zero
__(Fig.2). The "rigidity of the joint" arx1 the "break of the characteristic" are the
6
8?,
__basic values which deter-ne the quality of the assembly of a joint.
10--
Thermal stresses. In the process of working, the operating temperature of the
12--
14-1
machine-part-tool system changes. As a rIsult of this it is difficult to determine
analytical means the effect of the deformation of a part, caused by- the action of
heat, upon precision in production. At the same time, temperature strains may have
18
__a substantial effect upon precision in machining. For this reason, in planning tee
20
_nological processes one must provide for onditions which will weaken the effect of
22_
__temperature on precision in machining.
24?
Internal strains. Internal strains crop up as a result of cast shrinkage,
26_
30
32
34
36
3
40
--And also vibrations
42_1
--ting edge, etc.
uneven plastic deformation, heat treatment (hardening) anil other causes.
The effect of internal strains may be considerably reduced by creating a ratio
al design for the part, by perfecting methods of machining, and by introducing into
the technological process special operations to remove internal strains (ageing, for
example).
Other errors. In this last class belong errors which depend d:trectly upon the
fluctuations in clamping pressure, unevenness of supply, etc.,
in cutting* errors connected with the action of the tool's cut-
-.worker, for example
Methods of Precision Analysis and Computation of the Technological Processes
STAT
For precision computation of the technological processes, two methods are used:
Vibrations in the cutting process are reflected chiefly in the smoothness of the
54 ?eturfacey?This-problent-is--examined -detailed--analysis,
56-1
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1) the calculatorp-analytical and
2-4
experimental-statistic
In the calculatory-analytical method'i the causes of production errors are ex-
, 6
- posed, azxl analytical relationships between the production errors ani their causes
- are established.
10-
12-
14_-
16 ?
18_
20_
22_
24-
26 ?
? 28--
30_
32
34
36
3 a--
-
40_
Fig.3 - Effect of Vertical Dis-
placement of the Center upon the
.Precision of Diametrical Di-
mensions
The calculatory-analytical method is the
prolessive method, since it permits direct in-
tervention in the technological processes.
However at the present time the problem of
the total error can hardly be
dete
solved, in practice, on the basis of analytical
collations alone, since for the time being we
still lack the exhaustive calculatory ant em-
perilental data which would permit us to deter-
mine
the influence exerted by all primary err-
ors upon the precision.
The calculatory-analytical method is used chiefly to analyze the technological
process with a view toward establishing the effect of basic production-technology
factors upon the production errors. To determine the total (resultant) error, the
experimental-statistical method is used.
Let us examine some examples of the use of the experimental-statistical method*
42_
? Example. To determine the effect upon the precision in machining caused by the
44_1
--displacement of the center of rotation of apart due to the action of the tangential
46
component of the force of cut.
48
50
5
- 54
56
If the center of rotation 0 (Fig.3) of a part is displaced by As in a vertical
direction aril occupies position 01, the error of the radius r will be
-examples-are-borrowed-frcer-Bibl.3.
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0
2
4]
? 6
8
10 -
12
14 .-
16 ?
18 _
20-
22 _
24-
26 ?
? 28-
-
? OC=jir* +AO ? r=r(V1+? i)=
ra
I
A 2\ I
I
The expression ()
1+------z7_-1/27 be expanded into a series. If, in this expan-
sion, we restrict ourselves to two terms we obtain
(i+--) =i1+;;.
rt 2
Substituting this into the original
Ar...121
AzI
2r 41
. ?
tion we obtain
1 Example. To determine the effect of the form and dimensions of a blank upon
30_ the Accuracy (precision) of machining the part on an automatic longitudinal lathe.
32 As a result of the action of the components Pz and Py., the center of the rod is
34 displaced from point 0 to point 01 (Fig.4)*
36
It is evident that 001 is equal to half
3
the gap between the rod and the rest bearing.
Z7 I
40 Disregarding the vertical displacement,-
42
44.
46
48
50
Fig.4
we can determine the increase in the radius of
the part by the formula
? cos,.
2
ore z is the gap between the rod and the rest bearing.
If we take Py 0.4P5, then tan. (i) 2.5 and (1) 23 00 ?
5-
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4?\
6 _or_the_diamstral_error_isA
?=1????1
Ar cos 68?.0,185.g
2
8_ The experimental-statistical method is based on the theses of the theory of
10? probabilities. From the point of view of the theory of probabilities an error which
12 occurs in machining is an accidental quantlity which depends upon a large number of
14_ production-technology factors.
16-- If we execute a number of parts under a practical.17 unchanging technological
18_ process, all the measurements of the machined parts will differ. This phenomenon is
20_called. diffusion of measurements.
22_ An error which has no constant numelcal value may be characterized by a distri-
24?bution curve (or by the corresponding Table). Determining the diffusion of errors
26 with the help of distribution curves con-
28 0 S sista in the following: Let us assume that
30 in some established technological process,
32 1 we have machined a number of parts, which
34 we have measured with a universal measuring
36 -70 -60 -50 -40-30 -20 -10 0 #10#20 tool. As a result of the measuring, it is
a)
3 established that the error x is character-
Fig.5 - Distribution Curve
40 ized by a certain combination of numerical
a) Readings of the measuring instru-
42 values which represent its deviations from
ment in microns; b) Frequency
44 the nominal dimensions. Let us write the
46Jresultant deviations in a decreasing order of their absolute values. Then let us
48:]break down the series of deviations into intervals (the smaller these intervals, the
5O_4.e exact the construction of the curve) and Count the number of parts in each in-
.
52jterval. On the basis of the data obtained let us compile a Table according to the
54 -columni--let-us -show-the-intervals-of-the-deviations
56
microns); in -the- second, -the - absolute frequency-mthe.
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ber of deviations in a given interval; ana in the third, the relative frequency Ill-,
absolute-falequency._of_a_measurement_to_the_overall__--
2
4_01
100inutber of measured parts (see Table 1).
61
On the basis of the data of Table 1, let us construct a distribution curve
8
(Fig.5). To do this, let us lay off
the values of the errors along the ex,.
a) is 24 and the absolute or the relative
Ira" I to frequency of a measurement along the
10 --
12--
14_-
16--
18_0
20__
22__
-0
24--
,
26_4
? 28--
30
32
Table 1
b)
?60 ?50 2
?50 ?40 5
?40 ?ao 9
--30 ?20 as
?20 ?10 59
; ?10 0 57
1 0 440 13
0,011
0,027
0,050
0,194
0,328
0,318
0,072
180
1,000
a) Intervals in deviations in microns;
b) Absolute frequency m; c) Relative
340_ frequency d) Total
360_
axis y. The resultant broken line is
transformed into a smooth curve when .
the number of intervals is increased
limitlessly, and this is called the
curve of distribution.
The outstanding Russian mathema,
tician A.ILLyapunov (1857 - 1918) has
demonstrated that, if an independent
quantity is the sum of accidental in-
dependent quantities which are as'num-
--erous as one chooses, this quantity, as soon as certain additional conditions are
38-1
-isatisfied, will follow the law of normal distribution as accurately as one chooses.
The factors which have an effect upon precision in machining on metal-cutting
42_I I
chines, and which are brought out in the' works of N.A.Borodachev
44
_JYakhin (Bib1.5), and other authors, show that the basic condition of larapunovls the
46jem (multiplicity of factors in machining On metal-cutting machines) is satisfied.
48:d
SO
In addition, a great deal of experimental research, whose results have been
stematized in the above-mentioned papers! by N.A.Borodachev, has established the
5
act that the distribution curves of errors (dimensions) in parts under machining,
54
--Ion machine tools, obey the law of normal distribution.
56.4
1
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10-
12-
14_
16
18
20
22
24
26
20
30
32
34
36
3
The equation for the curve of the no distribution law has the fora
where y is the deviation frequency, corresponding to the abscissa N.;
e is the basis of natural logarit (2.7181..0;
n is a constant quantity (3.14..0;
a is the mean-square deviation
a=
Eni(xi?xcpr
L=1
)?
X=3 X =4
x
1-
.Fig.6 - The Effect of 1: upon the Position of the
I
Distribution Curve
40 1
?*here N is the overall number of deviations;
(2.2)
( 2.3)
42__
--
--
46__
48--
50?
52,?
ni is the
xthean is the
A study of
frequency in the ith interval (i = 1,
arithmetic mean of all qrantities
2, 3#000-, kl
..0
x, determined by
k
E niki
1-1
the formula
(2.0
is symmet-
xini+x2n2+... xhnk
X=
man==
ni-t-n2+ nk
N I
the equation of normal distribution shuws that the curve
.54
with respect to the axis passing through the point x= xmart, in which the
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curve maximum is located. The inflection ilvints are located at a distance of t a
2
_..from_the_center.__ On _both sides, __the_ curve asyaptotically-approaches-thot Ards I
4_1
The equation of the curve depends upon thJ two parameters xmeari and a.
When xmean is changed, the curve pre erves its form but moves along the axis I
8 ?4
-i(Fig.6). When a is changed, the curve changes its form (Fig.?). The probability
10-
12-
22
24-
-
26_
Fig.7 - Effect of a upon the Slope
of the llstributiGn Curve
Fig.8 - Probability of Obtaining
Parts with a Deviation of ?Np
28-
that the errors will not differ from the mean value by more than tx0 (Fig.8), is
30
-equal to
32
34
36
3
40
42
4 4_
46-
1
ar-fiTt
+x. (x-Ammi_
e 2.1 dx.
(2.5)
The value of the adduced integral is denoted by I. (z) and is determined by the
elationship
?.
a
_
In Appendix 3 we are giving the numerical values of the adduced integral, as a
48
ction of z. Using this Table, it is easy to determine 4 (z) and, consequently, to
50
etermine the maximum deviation from the mean value.
5
54
A3 an example, let us determine the maximum deviation xo with a probability of
56
0%, it being known that the distribution of errors obeys the law of normal distribu,.
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?I tion, and that a .- 0.02.
2-i I
itaien_4(z).=_0.90, we _find fivra_the_ Tablea_(aee_Appendix_3)_ths.t
4_1 I - ? - - - - -
I ?---i
6 z=----L)=--1,65; xo=za I
a
8 1
I
or 20 It 1.65 x 0.02 = 0.033 nK?
10 ?
When x0 .? ?3a, we have z ... 3 and 1)(z) = 0.997, 1.. e., the probability of ob-
12 ? I
, tabling parts with deviations from the mean value within the Limits of t 30 is 99.73
l4__I I
_ With a probability of practically 100%, we may assume that the maximum deviation of
16? I
___ errors from the mean value is equal to Oa, under the normal law of distribution.
18....,..
The full *field (or base) of diffusionA will be
20_ i P
I
22_ 1 Ap=60. (2.6)
24:1 I
The experimental-statistical method is widely used for analyzing the technolos-
26
:_-ical process. When the technologist wishes to establish the degree of the effect of
20-1 1
_J some factor upon the precision in machining, he makes as accurate a comparison. as
30._i I
possible of the distribution curves constructed on the basis of measuring two groups
32_1 .
__ of parts produced under conditions where the action of the factor of interest here
34_1 ,
was different in both cases, but the remaining conditions were the same. For irk-
36_1 ;
1
c.j at anc e, in a study of the effect of a given type of coolant upon the precision, we
3
1
-nnust produce two groups of parts on the same machine, under the same cutting condi-
4 0....J I
--1 tions, with the same material, etc., changing only the type of coolant. To obtain
42 I 1
.
_
?ia reliable distribution curve we reconmend making approximately 100 to 200 meas-
44_1
1
--Jurings.
46_1
-- The number of parts, which must be measured in order to determine the mean-
square
48-d
?deviation, depends upon the accuracy with which we want to determine this
504
I
. --Ideviation. !
52--
? 54 However, in practice, sufficiently reliable results may be obtained When the
?'number of nwmunnrings is equal to approximately 100.
56
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?
.1????4
From Mathematical statistics it is e4ident that the mean error in determining
a
2-4 1 t
. __Lthe_man-square_deviation_ls_equal_to -1- . ,_rtryl in determining-?ae-aeazi-
4_4 a
- arithmetic deviation, to ?-, where n is the number of measuring'.
6 at
!
Thus, in order to obtain a with an accuracy of ?5% we must measure the follow-
- ing. number of parts:
1 0 -
12-
whencewe obtain n 200.
16 --
__ In order to obtain the mean,-square deviation with an accuracy of ?10% we must
0,05a=
a
3/ 2 (a -
18
__ measure 50 parts, etc.
20H
22:1
of accuracy and reliability of :mmean arida, obtained as a result of measuring these
In cases where the number of parts is less than 25, we must evaluate the degree
24 D E
. . -*amts. The indicated problem is solved in courses of mathematical statistics in the
,
26 :11following manner:
. 28:iLet the arithmetic mean, obtained on he basis of the measuring of n parts, be
30_1
?equal to xlnean, and let the mean?square deviation be equal to a. Further, let us del
32-_1
fine the accuracy e with which we want to determine the arithmetic mean, and let WI
34:d find the reliability a depending upon the number of measured parts n.
36_1 I
?, The reliability a is equal to the probability that the real arithmetic mean a
38-1
is to be found within the limits of i
4 Og I
I
42?I i zi...?e aAct .N....i-a. I
1
44
46
48
50
? 5
-- I
The accuracy e is determined in accordance with the following formdla (see
1
ib1.6):
e..
prn
Knowing n and e, we can find t1 and, using Table 231%, we can determine a
q 4-1
1*---A-more - -compl ete -Table -is -given -in ImniL.6.
cA-1-
_313?
S TAT
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? '
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0
-
?
.10.111
_Table_2
4-
61
n-1
1
2
3
4
5
6 7
8
Li
10
0
1,000
1,000
1,000
1,000
1,000
1,0G0
1,000
12 0,5
0,705
0,667
0,651
0,643
0,638
0,635
0.632
1
0,500
0,423
0,391
0,374
0,363
0,356
0,351
14
1,5
0,374
0,272
0,231
0,208
0,194
0,184
0,177
16 2
0,295
0,184
0,139
0,116
0,102
0,092
0,086
18 2,5
0,212
0,130
0,083
0,067
0,054
0,047
0,041
2,9
20
224
0,211
0,101
0,063
0,044
0,034
0,027
0,023
2
1 9 1 10
8
1,000 l.000j 1.000
0,631 0,629 0,628
0,347 0,343 0,341
0,172 0,168 0,165
.0,081 0,0770,073
0,037 0,034 0,031
0,020 0.018 0,016
_
Exarmle. Todetermine with an accuracy of 0.50 the reliability of the value of
26
, obtained on the basis of measuring four ;arts.
20 mean
Let ns find
30_
34_
-
3 2_ ern- 0,56-1a-
a - a
=1.
3 6_ According to Table 2 we find that the probability P of values of t1 which are
38-numerically not less than 1, is equal to 0.391 for n - 1. im 3. Consequently, the
40_Hprobability of the opposite inequality will be whatever mist be added to the precel-
42_ trig inequality to make 1, i. e. will be equal to 1 - P:
44_
a=1-0,391=0,609.
Xrra.
46_
-n
48- In evaluating the accuracy aid reliability of a, we must determine the probabil-
.
50-ity of the fact that a will be confined within the limits a - c and 0 + e. This
rerl
-'-'-yrobabil.ity is equal to the difference P1 P2, where P1 and P2 are the probabili-
-54:/ties-determined according to Table 3 and corresponding to the values
56
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?
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re.
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2-
4
6
_
2 (n - 1) a*
X, ma. and
^ (a + ar
I
14-
16-1
18_
20__
24_J
261
2EL-
1
2
4
6
8
10
12
14
Table 3
1
2
3
4
0,3173
0,6065
0,8013
0,9098
0,1514
0,3679
0,5124
0,7358
0,0455
0,1353
0,2615
0,4060
0,0143
0,0498
0,1116
0,1991
0,0047
0,0183
0,0460
0,0916
0,0016
0,0067
0,0186
0,04C4
0,0005
0,0025
0,0074
0,0174
0,0002
0,0009
0,0029
0,0073
(2 7)
- 1) al
.
1
- a),
5
? 6
7
8
0,9626
0,9856
0,9948
0,9982
0,8491
0,9197
0,9598
0,9810
0,5494
0,6767
0,7798
0,8571
0,3062
0,4232
0,5398
0,6472
0,1562
0,2381
0,3326
0,4335
0,0752
0,1247
0,1886
0,2650
0,0348
0,6620
0,16
0,1512
0,0156
0,0296
0,0512
0,0818
30_ Example. To determine with an accuracy of 0.5a the reliability of the value of
3211the mean-square deviation, obtained on the basis of measuring four parts:
34j
36_1
3
40H
-for x2, we calculate
42_
(4- 1)a'
-1,33;
(a+0,501
(4 - 1) at
X2 .12.
2- 0,54:
Further, according to Table 3, for n found
3 and for the values we have fou
44_
46_
P1=0,7871/04 Peg 0,0074,
P=0,7871-0,0074=0,797.
48- By using the stated method we can easily determine the accuracy ani reliabilit
50-of the basic statistical indexes ;lean and a depending upon the number of measured
52::iparts.
54-----1.1 et-us-consider-some examples of the use of the experimental-statistical-methodr
.4-To-determine the amotuit of the total error occurring-in-the- cutting-
S TAT
1Cosk
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0
H 1.4 x 0.3 thread on a aorew-cutting iachins?
result .of. measuring 180 parts,.. jre_ have_established_the ..deviations_trom-tha
2
greatest value of the mean diameter. These deviations are graphically represented
6
_ in Fig.5 and Table 1.
Let us determine the value of the arithmetic mean in accordance with eq. (2.4)
8
10-
22_
2 4?
.
. 76?_
28?.
30_
32_
34--
3 6
3
40
L
_.1
?55 ? 2 ?45 ? 5 ? 35 - 9 ? 25 ? 35 ? 15 - 59? 5 ? 57+5 ? 13
180
_ _11
--14,61.
In order .to determine the mean-square deviation, let us draw up Table 4.
44
DtVidflOrl n?icrons
(xi ?x.)1
?
ni ?
JIMto
?60
?50
2
?40,39
1631,35
3262,70
?50
?40
5
?30,39
923.65
4617,76
?40
?30
9
?20,39
415,75
3741,77
?30
?20
35
?10,39
107,95
3778,25
?20
?10
59
?0,39
0,15
8,97
?10
ST
+9.61
92,35
6263,95
0
+10
13
+19,61
384,55
4999,15
E? ?Tvar=25672,55; aims V 25672,55 .11,95 m;crms.
180
42
Consequently, the greatest deviation from the mean value is equal to 3a ?3 x
44
__x 11.95 ga ?35.85 microns. Assuming that the distribution obeys the law of normal
_:distribution, we can reckon that the total error is equal to 6a, i. e. 71.7 microns.
4 8_1
--Under these conditions, the probability of determining the zone of diffusion (i. e.
?6c) constitutes, as has been shown above, 0.9973, i. e. practically 1004
52?
Example. To determine the percentage of suitable parts in the machining of
?,cylindere with a diameter of 20_00. (Fig.9).
56_1,
? STAT
1
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I
On the basis of measuring it has beeb established that the curve of distribu-
2-1
_ tion_obeys_the_law of normal_distribution'with_a_meau-squaro_devlation_of -er ?
7...1i?
= 0.025 mm, the apex of the curve being displaced 0.03 am from the center of the
6
1
4 I
...: field of tolerance toward the go-side of he gage.
a
The probability ofobtaining suitable parts is
10 I
1
1--_
12
14 ? where
1
16? Zi-
1 I - - xl 0,05+0,03
' ? ...3,2, .
a 0,025
18_x.2,3? j 0,05 ? 0,03
20.
a 0,025 -0,8.
.4. .
1
22_ According to the Table of adduced integrals (Appendix 3) we finl that (ZA) ..,
? I
24? = 0.499, and (ZB) = 0.288, 1
? i
-----------
28 ?_i
26_
_ I
--
30_The probability of obtaining- dimensions
I-
_ !
32_ greater than the measurement of the go-gage
34 (corrected defect) is equal to
'
36 1
' 0,5 ? 4, (?B) =6,51:0,288.0,212.21,21/.. I
1_
??1
/ /4'
A:4 X I
I
40 d -Example. To determine the correctness of
I__
42 setup on the basis of measuring certain test
Fig.9 - Probability of
44
Obtaining Suitable Parts
46_
a) Center of the field of
parts
It is evident that there will be no defect
48? in machining if the arithmetic mean of the en-
tolerance
50-- tire group of machined parts Tinean is to be
52?found within the limits (Fig.10).
54-D
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The problem, consequently-, boils down to judging the position of ;newt on the
2 __basis _of. .measuring _ a_ szoall_number_ of_parti
?
4H I
In the example analyzed above we have shown that if x is reckoned on the
6 i? mean
__!basis of the measuring of four parts, i. t. with a probability equal to 0.609, we
may expect that x will not differ from L more than ?0.50:
10-1 mean mean
If the number of parts is increased to
nine, the probability will rise to 0.83.
Thus, by increasing the number of meas-
ured parts, we raise the probability of ob
12-
14_
L
18_
20_ Fig.10 - Ektreme Positions of the
92-d Curves of Distribution when
statistical methods of analysis it is importan
24-- 8>120
to mow withwhat degree of approximation the
26_1 empirical curve of distribution, charactetizing some technological process, maybe
28
=dtaken for a curve of normal distribution.' This problem is examined in detail in
30_1
specialized literature.
32:]
31-4? Conditions and Probabilities of Obtaining Set Tolerances in the Production of
--Parts
I
Aug :Xean with a given accuracy.
m
In conclusion we should note that in the
36_
Ehking use of the statements set forth above, let us examine the conditions and
38--
:possibility of obtaining set tolerances in the production of parts*.
AU 40
the causes of the errors which are possible in machine operations conducted
42_1
4in accordance with the principle of the automatic obtainment of measurements, are
4
--!.divided into three groups:
46_1 3) those which depend upon the type of machining;
2) errors in the set-up;
50-
3) errors in the basing.
59
To the first group belong errors which occur as a result of fluctuation in the
54
56--j*-Here-weAset-Atrth-the method proposed by Prof.Aaaakhin.
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'mechanical properties of the material, inithe chemical composition, in the amount el
2
910.1orimnce,_ete.
4
A notion of errors in set-up may be obtained from the following example.
811
103
18
Fig.].]. - Setting on
20__
a Plane without Error
22
24-J
. 26-1
in Basing
A.
dolts
-
Fig.12 - Change of Position
of the Curve Of Distribution
Depending upon the Set-up
Fig.13- Setting on
a Plane which Causes
an Error in Basing
Let US assume that we have machined a group of parts with a single rillin cut-
23J ter and without under-tooling the machine:(Fig.11). Hawing measured the machined
-1 30-parts according to the measurement a, let us find the error, which depends upon the
32__type of machining, and let us construct the curve of distribution (Fig.12). Then
34:1
let us effect the set-up a second time, and execute a group of parts. It is evident
36:--1that the curve of distribution of the measurements of the second group of parts will
I I
38-Idiffer by AH from the curve of distribution of the first group of parts (Fig.12),
-1 1
4n---,since it is impossible to accomplish a set-up with complete accuracy.
__I ,
'
421
40ample (Fig.13),
45:1
A conception of an error in the basing may be obtained from the following am-
In milling a ledge (Fig.13) we must keep a measurement L, reckoned from the
48-plane A. It is evident that the accuracy obtained in the measurement I. will depend
56:1upon the accuracy of measurement 114.
Keeping the measurements of all the machined parts within the limits of.toler
A-1
ance-is -possible on3,T on condition-t.hat
56-1_
STAT
1
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?
- - -
Ap+As+Ay 0.5 mm. In aircraft in,.
strunent construction, such a method finds very limited application. Rolling is usea
36:1 1
--for gear wheels with a nodule of 0.3 - 1 mm. This method is still used in the ao-
33?
--ceptance stage. Pressure casting and drawing are also seldomused.
40__
42_
4
Materials.
In instrument construction, gear wheels are usually made of steel, brass,
46 I
ronze, etc. Decisive factors in the choice of material are cost of machining, re-
48_- 1
--,sistance to year, and high corrosion resistance. To reduce wear different materials
50-1 1
. ?,must be used, as far as possible, for a single pair of gearwheels, such as steel 1
52,-1
?and brass, bronze of different types, and the like.
t
1
. 54__i
-1 For low-speed gear transmissions, we generally use L559 brass. This is pre-
56
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0
ferred over steel since brass is &may ?'- chined and subject to little corrosion.
2-4 ? Eli_steel_and.MOLAteel_are_mostly_used_in_making_pinions_anditormas__Be_mse of
4_
_their small dimensions, these parts wear out sooner, and for this reason they must
? 6
be subjected to heat treatment. Bronze ol A10 and AMts9-2 types is used in making
8-i
worm gears where high requirements as to resistance to wear are made. Textolite is
10
12--
'18_
20_
28
30_
32__
34__
36_
3
40
42:1
also used as material for gearwheels.
TV,
0.3
40?
-t1.06
NI ?
Zo7
ru
? cs
445 4778/
a)
Zst 12
m.= 82
......
.... .eeb a x 20'
o
0 ti
b
S '72178 b) ift
o
0' o
I'.;
T
c)
728,
18
a
Drivinl Gear or Pinion
a) Ellipticity of diameter 0.8:8Z.not more than 0.12;
b) Taper 1:50; c) Material U7AV steel red-hot Re 50 - 55
. Technology of Executing Typical Parts of Tooth Gearing.
.
Driving Gears
The technological process of machining driving gears consists of a series of
44:1 --operations: 1) preparatory operations; 2) teeth-cutting operations; 3) heat-
46_1 --treatment operations (these may be omitted); and 4) finishing Operations.
48-4
Let us examine the standard technological process of machining a driving gear
50-1
--(Fig.181). The preliminary operations consist in preparing the bars (straightening
52-n
--And cutting) and turning. The turning is usually done on automatic longitudinal
54-J,
56
--lathes or on turret lathes. In choosing a turret lathe or an automatic turret
-
STAT
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? ?
.........trat-eattaa-ar a
_ichucking machine, and in fixing the sequeUce of stages, the specifications given in
2-4theChayteNxles_aShafte,ust_be_followel,_BincethethiAnk_fnr K driving gear
4-
6
must be treated as an axle.
16 ?
18_
20_
Tooth-cutting is done by the duplicating method (since driving gears usually
have less than 17 teeth).
The disk gear cutter (Fig.182) is used as
the cutting tool in gear-cutting. From the
thelry of meshing of gear wheels we know that,
_ for evert number of teeth, there is a special
_
Fig.182 - Disk Gear Cutter
profile. Thus, in order to obtain the exact
profile in cutting by the duplicating method,
22_4
each number of teeth must have its own cutter. Special cutters are made only in
24:1 cases of large-scale or mass production. Usually we use gangs of 3, 8, 15, or 26
26
:lcutters, each of which is designed to cut a gear 'wheel with a definite number of
28-
30--
32__
34__
1 \
r
/ ?N/
4.
361
/ -
r A ' 4 '7 //.".? . e / . ,
/
r /
36 '
Fig.183 - Schematic Sketch of Milling
381
40
42__
of a Pinion Tooth in Three Passes
Fig.184 - Setting of Cutters on
Arbor in Milling in Three Passes
44:teeth (Table 28).
461 In connection with the necessity of Obtaining a high degree of accuracy and
48?smoothness in the profile of a tooth, the machining must be done in several passes
50:J(in our case, three). Depending upon the type of machine, this may be done in ei-
-d
-- her of the following yam
54 1)-Eadh-pass-is-earried
561-1- three -43 utters-are --set - on -the
out-by a separate
arbor (Fig.14).
cutter (Fig.183).---In-thismethody-1
The first is the usual-sp3.ined-cutter;
STAT
t.t-
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0
the second is near the final profile &mansions:ad form (allowance of
);
4
_igoes into action. After it has cut all the teeth through, the cutter carriage is
6
displaced, and the second cutter is set into working position (a worn cutter maybe
8
__used for the second one).
10?
After the carriage is shiftsd again,
I.
/
I*4-111119
?/./
20_ Fig.185 - Schematic Sketch of a
22:J Pinion Mounted Conically at the
24-- Driving Center
26_.
__Mrs relative to the axis of the part being machined; at the negligible allowances
28--
?left for the smoothing passes, this may lead to the formation of bare spots.
30_1
thethird cutter is in operating positions
2) All the passes are done by a sing-
le cutter. In this method, one cutter is
set on the arbor of the spindle; in the
first pass it is not lowered to the full
depth of the tooth, and only rough cutting
is done. After ail teeth are cut, the
ter is lowered farther into the part.
One shortcoming of the first method is the inaccuracy in the setting of the
32
34
36
3
40
42
?
Fig.186 - Schematic Drawing of Mounting
44_
by the Driving Center, Set in the Dad
46-
- of the Pinion
48--
a) Journal; b) Mod
,r
Fig.187 - Construction of the
Driving Center
a) View from A
50--
52-- A Shortcoming of the second method is the increased wear of the cutter.
54 In recent-timesvindustrial plants have been using special-devices-to-set-the?
.
q4-1
--cutter-accurately-with-respect to the center of the part-being machinedvas-a-reaulti,
STAT
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10
12 A 12-20 1 12-13 1 12 1 12:
14
14-15 2 14 2 14
16 21/2 15-16. 21/2 15.
18 2s/4 16
20 3 17-20 3 17-18 3 17:
31/4 t
22
? 31/2 19-20 31/2 19,
24 33/4 20.
26 21-54 4 21-25 4 21-22 4 2t
28 41/4 22.
41/i 23-25 41/2 23 ?
30? 42/4 24-25
32 5 26-34 5 26-29 5 26-2T
34 5114 28-29. '
36 51/2 30-34 51/2 3O-31?
5$/4 32? 34-
35-54 6 35-41 6 35-3T
40 61/4 38 ?4 t
42 61/2 42-54 61/2 42-46
61/4 47-54.
?
44
C 55 and mace 55-134 55-79 7 58-65
46 71/4
48 ? 71/s 80-134 71/2 b0? 102'
73,14 103-134
50
135 avtd more 8 135 PIA mere 8 135aa more
5 -
54 41,54 of_3 cuttere;_bi Set of .8 cutters; c)Set_of15_ cuttereLdl_Set_of 26
_ter's; e) Cutter; f) Number of teeth on wheel being cut; g) Nosof cutter:
56' -
11/s 1 13 11/2 13.
??? 16111",.....14??? .741 0,9 #1,????????
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..e.?mrxwerakagovortsca.itagg'1
? /V
0
the first method must be considered superior, since it pernits the cutter to operate
2
_for_a_longer_period_without being_resharpenel._
4 Setting and attaching the pinions being machined, is accomplished, with the help
. 6
of two stocks. If the journal of the pinion is sufficiently rigid, the fastening is
8
__dons by the driving center, notched (Fig.185) and set in the headstock. If one of
10
the journals is insufficiently rigid, the driving center is set in the end (Fig.186)?
12--
The construction of the driving center used on gear-cutting machines (of type
14_
--OZPO) is shown in Fig.187. The driving center has a conical aperture with notching.
16--
_The angle of the cone of the notched aperture is 30 - 50?. The number of teeth (of
18_
the notching) is usually 16.
20_-
22:1
24-
26..-..
. 28--
30--
32_
34
36
33:d
ANN 414
40__
42__
?_;..?,#AN
- -1--
Fig.188 - Structure of the Center Inserted in
the Indexing Head
The structure of the center for the tailstock is shown .in Flg.188. After the
1
teeth have been cut, steel pinions (in the majority of cases) are subjected to heat
1
treatment. The heat treatment consists in hardening and subsequent tempering. Hea
1
ing for the hardening is done in a special tube furnace, in a neutral medium. The
neutral medium is prepared by dissociation of ammonia with partial liquefaction of
44?hydrogen.
46_-
48_-
50?
The usual composition for the neutral menu:tie:
1
F12-75e/Wd N2--25?A.
L? ?
1
527 Heating in a gaseous medium (neutral) for pinions of II8A. and 1110A steel. is
--:dontrat-temperatures up to 780 - 800?C, with subsequent quenching-innixai----After
56.-JhAwillime:r-the-narts-are-sdbjected to tempering by heating to-200 =250?4-with =bi-,'
STAT
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0
J sequent quenching in oil (at 30 - /1.0?G). Pinions hardened in this manner have a
2-1 surface,. ani_ are __outwardly &pm ntinguishalle-from_a_surrace_obtained_by_chip.
4
6
10?
14_
16 ?
18_
20_
22_
24-
26?
removing after machining.
28--.
30_
To eliminate roughnesses resulting from tooth:.-cutting, additional finishing
(polishing) is required, which is done oni special tooth-polishing machines or on
clock lathes rigged with special attachm4ts.
Fig.189 - Diagram of Polishing
ofPinion Teeth
Fig.190 - Design of. the Prop for
the Pinion
32_1 The tool for polishing the teeth is a polisher made of wood (boxwood, palm,
34_ basswood) or of soft lead alloys, having a screw thread of the given module on a
36:1 cylindrical surface. The disk revolves at a speed of 15 misec, entraining the pin-
0-1
In addition to rotation, the pinion performs a reciprocating notion at a speed
"Hof 180 - 200 strokes per minute (Fig.189) GOI paste is used as abrasive in polish-
42-21ing. In the process of polishing, the pinion is placed on a prop (Fig.190) which is
1_
4-4-a disk with several grooves cut into its periery, for support. As the grooves
-1
4-4--weari out the disk is turned around. To polish the journals of the pinions, a sl
Q
A -1
-v_?jof hard alloy is used (see Chapter I, "Axles ani Shafts").
50-1 After cutting the tooth, the profile land pitch of the tooth are checked on a
5 Hprojector which enlarges 50 - 100 times. In checking, the pinion is set in the cen-i
54=1 ters-and--1-5-revolvel -by-hand -until the -tooth profile coincides with the
56 -Ithi a-way-wobbling-owl also be-checked.- A special screen is used for-this-,--- on-which-
STAT
t_vri
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-
0
a series of parallel lines is etched at a distance of 1=6 The outer diameter of '
2
the pinion coincides_with_one of_the_lines on_theiscreen.___Wobbling-can-be_determined.
--by turning the pinion.
6
I:d The outer diameter of the pinion is hecked by special calipers (Fig.191). The
8
--no-go side of the gage dno is distinguished fromithe go side dgo by a special cut-
10--
i
--out. After the journals have been polishil, they are checked for out-of-round with
_
the help of an indicator with special jaws Fig.192).
1 Out-of-round is determined in the fol-
iowing manner: By pushing the button (1),
the moving bit (2) is pushed aside. The
pinion journal is inserted in the gap
I
formed between the moving bit (2) and the
;
Atationary bit (3). Then the button (1) is
zeleased, and the reading of the indicator
i
is noted. By rotating the pinion, any de-
indicating out-of-round of the journal, will be noted.
12-
14-
16 ?
18_
20_
22_
32
LAlit INFAm'im's
Fig.191 - Ring Gage for Checking
the Outer Diameter of a Pinion >?
@
-]
--flection of the pointer,
34__
36?Sectors
3
40
--tor gear of the type shown in Fig.193.
--not only of the production of sectors
46:imaterial. Notching the blank is done
48--ening. This is followed by trimming,
Let us examine the standard technological process for the production of a sec-
. I
This technological process is characteristic
1
or racks but also of gearwheels made of Sheet
1
on eccentric presses with subsequent straight-
countersinking the aperture, and turning the
is riot
always. done). Cutting the teeth is
liomsomoletsnmachines or by the indexing
50---isector on the outer diameter (turning
:usually done by the rol 1 ig method on
5.17method on OZFO type machines. 1
56-1 Cutting the teeth by the rolling method has the following advantages:
STAT
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-
0
-- 1) Greater accuracy. This is explaiieci. by the fact that in the case of invo-
2--
, ....,imte_gearing the_eutter_has arectilinear profilejthe_form-of-a-trapezium-with-an--
4_
-
?angle of a = 200, Fig.194). A form such as this is easy to produce and easy to
? 6
10-
20_
22:
24-
26-
-
28--
30-
32_
34_
36_
?
7.
Fig.192 - Control Device for
Checking Out-of-Round the
Pinion Journal
Fig.193 - Sector
a) Along entire circumference; b) Coun-
tersink to02+?*25; c) Involute gearing
a = 200 d) Bccentricitys62.5 A3; e) Re
ative to the center, not more than 0.01
38-icheck. In addition, 1,ihen teeth are cut by the rolling method, errors in the indem-
-1
40--ing mechanism of the machine have no effect on the accuracy of the angle. On the
42?basis of research done by S.T.Tarasov (of the NVTU imeni Bauman), it has been estab-
44--1--lished that in cutting a tooth by the duplicating method, the thickness of the tooth
A6--!may be maintained with a tolerance of 0.02 mm, and in cutting by the rolling method,
48-xith a tolerance of 0.01 =L.
_
50= 2) Considerable increase in productivity. The machine time in working with the
_
1
52--duplicating method is determined by the formula
t
? 54Ls Ls 1
lim == 4- s--- -F Ts .4,1 -i- .
suk olk
re
( 3.1. 1)
STAT
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?
- -_
0
where Tm is the time for machining one pais, in min;
2
L 13 ths_length_ of_the cutter _pass equaL_to_the _leagth-of-a-tooth-plus-thie-
10-
12 ?
14
16 ?
18_
20_
92_
24=-1
26
28
30
32
34
36
38,
40_
42
cut and the run (rated length), 4.nIsm;
z is the number of teeth of the se tor (or wheel);
sm is the feed per power stroke, in =fain;
sox is the speed of backward action Tf the table, in mmizain;
T is the time needed for one turn of the sector (or wheel), in =tn.;
k is the number of wheels (sectors) s1nzaltaneous3y set on the chucks (with
the ends of the wheels touching).
The depth of cut is computed by the
Fig.194 - Worm Cutter
for=.1a
y cos cp t (d ?t), (11.2)
where y is the cut, in mm;
d is the diameter of the cutter,
in um;
t is the cutting depth, in zmz;
is the angle of inclination of the tooth, in degrees.
In a case where a straight tooth is being cut, cp 0.
Machining time when working with the rolling method is determined by the
formula
T =Lz ?
44_
m sni
46_
?where ; is the machine time for one pass, in Adz;
50-
52-
? (11-3)
L is the length of the cutter pass,1 equal to the length of a tooth plus the
cut and the run (rated length), in am;
z is the number of teeth on the entire circumference;
56:4
s is the feed for one turn of the cutter, in ay
STAT'
a-ba-
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?
0
6
n is the number of turns of the cutter, per minute;
_Lis the ?number of_cutter_settini54
The extent of the cut is computed by the formdla
22_
-r
24-
26_
y =-- cos ; (d? t) + 1,5 tg p (nt t),
where t is the depth of milling, in nig
23--
,
30__
32
34_
36_
3
40
42
44_
46.,
48 _-
50_
521
--1
(11-4)
d is the diameter of the cutter, in nsi;
0 is the angle of the cutter setting, in degrees;
m is the nodule of the wheel being cut, in mmi;
s is the number of teeth of the loolheel being cut.
In work done by the rolling method, greater productivity is reached, i.
Fig. 195 - Design of a
Sector Whose Teeth Can,-
not Be Cut by the Roll-
ing Method
a> R (Fig.195);
e?,
less time is spent on the return stroke and on turn-
ing the part in the process of cutting the teeth.
3) as.s.12221sid. To cut a wheel of a
definite rloodule, only one worm cutter is required,
regard1es1 of the number of teeth of the wheel.
Despite the obvious advantages of the rolling
method, the duplicating method must be employed in
some cases of instrument construction, for examPle:
a) In cutting ratchet wheels;
to) In cutting sectors (rolling method nay be
uneconomical because of excessive idle motion);
c) Ii cutting teeth in special parts, where
1
d) In cutting wheels with a small nuMber-of teeth. .
Inspection of the sector after tooth cutting consists in checking the profile
on a projector !ind measuring the outside radius of the segment by means of special
(Fig.1960).
56
STAT
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HCylindrical Gear Wheels
41 Let us examine the technological pro ess for the production of the wheel de-
6 ipicted_in_Fi.g.19_7_.___Machining_the b1s'*j a lathe,_w_eparatory_tn cutting nf the
10--
12_ on machines operating on the rolling method.
14-- d In tooth cutting, the blank of the wheel is
16? sq in the arbor and clamped by a nut or by
18_
th running center. To secure the necessary
Fig.196 - Gage for Measuring
ac uracy in the tooth cutting, the technolog-
the Outer Radius of a Sector
22_ ical process must be so laid out that the pr
24?paratory operations, which precede the cutting, assure a sufficient degree of amen:-
?
26racy in the basing surfaces (in our case, the apertures and ends). As a rule the
28_iaperture must be machined to 2rx1 class accuracy. Arbors for gear-cutting machines
32 ihrosiOPOB
2
34__
36__
teeth, is usually done on turret lathes or
automatic lathes. The tooth cutting is done
Fig.197 .
.1N
,,,,,460441111
:=MOnsiEr
01011111
L__. 8
Fig.198 - Installation of .(Adjustable)
46?are prepared on the go side of the operating gage, to assure seating of the blank
48?with a minimum of clearance.
50:] In view of the high requirements for accuracy in the gear, a set of arbors is
52-used. For example, if the gear wheel has a 6A aperture, three arbors are made,
their-working-part s -having- the- dimensions;
56-1
1
STAT
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0 6-cool; II? 0 6,007-cool; III ? 0 6,012-coev
4
?
6 ____Zor_this the_blanks_ into which_ teeth_will_be_ cut_niutrt_be_al=angecLintogroups_b____
8: forehand.
10 The accuracy of the gear cutting is also increased by the use of built-in ar-
--
bores (Fig.198). The base of the arbor (1 is immovably fastened to the table of the
14_ machine. With the help of four bolts, th transition collar (2) is screwed to the
16?base. The bolts pass through the apertur s in the transition collar with a clear-
18_,ance, which permits the collar (2) to be displaced relative to the base (1). The
20_ collar position is checked with the help of the usual indicator gage.
IM i NM
r4
? Fig.199 - Diagram of Running-in
Fig.200 - Diagram of Generating
of Teeth on the Blank with Three
Standard Wheels
a) Blank
467 In cases where the above measures do not lead to the desired results, an addi-
48?itional operation is required, involving the machining of the aperture after the
50?teeth have been cut. For this, we must provide a tolerance for machining the aper-
52---iture, and must machine it in a special device.
547-1--The- technology-for machiring of wheels-with screw teeth differs--3ittlir-from--1
56_ t C4 -of-wheels with straight teeth.---In- cases-where the-teeth--are--cut
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0
???
- lath a disk gear cutter by the inde3cing 1Inthod, the cutter is selected for a fictitil
2,
__Dua_ranober_of leeth_in_accordance_with_the-forzula
4
6
COS 11 2
1.1 5
8--
_where s is the number of teeth of the wheel. being cut;
10,
zi is the fictitious number of teeth
12?
_ cc is the angle of inclination of th teeth.
14_
If the teeth are being cut by the rolling method with a worm cutter, the angle
16,
of inclination of the cutter axis is de-
18_
fined as the algebraic sum of the angle of
20_
inclination of the cutter helix and the
22_
angle of inclination of a tooth relative
24
to the axis of the gear wheel, 1. e., when
26
the direction of the helixes (on the wheel
28
? and on the cutter) is the same, the angles
30 Fig.201 - of
are added up; when it is different, the
32
angle of inclination of the cutter helix
34
is deducted from the angle of inclination
36
Diagram of Generating
Teeth in the Blank with One
Standard Wheel
a) Blank; b) Standard
of the wheel tooth.
3
In some cases, finishing operations are applied after cutting the teeth, in or-
40
_der to increase accuracy and smoothness.
42
Let us examine the basic finishing operations used in the execution of cylin-
44
?drical toothed wheels.
46:
Running-in. This method consists in placing two coupled gear wheels in a specit-
48
sqal device and making them revolve (Fig.199). With this method, no noticeable im-
?
?i)rovement in the quality of the tooth profile and smoothness is observed. This meth:-
52-
--3d does not provide for interchangeability of the parts of tooth gearing'.
54
6 Generating. The generating method is distinguished from running-in by the fact
5
STAT
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-Ithat, in this case, the generating of the gear wheel which is being machined is done
2-A
?with_three_tempered_standard_wheels,_executed_with_the_greatest_accuracy4Eig.200),-
6-1
tile standard (Fig.201). Under the influence of the pressure created between the
8-1
_ standard and the blank (the gear wheel being machined), in the process of their ro-
? _tation, the gear wheel is machined. This methodis suitable only for non-dry gear
10-
12-1
wheels. The surface of the teeth after machining is noticeably improved.
14 -I
or else with a standard wheel and two idler wheels which force the gear wheel a
16 -
18_
2 0_
22_
24-1
26 7
28-
30
34d Shaving. To increase productivity and to obtain better quality in finishing
36_ithe teeth, shaving is used.
3c-1 The essence of finishing the teeth of non-dry gear wheels by shaving consists
40_1n scraping off a hair-thin chip from the aide surface of the tooth with the help of
42_2a special tool (the shaver) which is designed in the form of a rack (Fig.202) or in
44-Jithe form of a toothed wheel (Fig.203). For finishing straight-toothed gear wheels,
4 g.;_ia rack with oblique teeth is used (Fig.204); for machining helical-toothed wheels,
48_Ithe teeth on the rack are straight. This is necessary to amplify the slipping mo-
50-ftion of the teeth and to secure uniform war of the teeth. The rack executes a re-
-
52---1
jciprocating notion which revolves the wheel being machined, and the wheel is drawn
54 --ionte-the-rack--auider-some- pressure.-- The wheel, during this process,--is-gradual.17
56- shifted-along- its -axil -(for uniform wear of the rack). - As a result of the -intere
Fig.202 - Diagram of the Rack
Shaver
Fig.203 - Diagram of the Wheel
Shaver
S TAT
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STAT
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0 ,
:sified slipping
2:4
_i_Scrape_thin _ chi
4_1
ing is the compl
motion of the coupled t
e
eth
the cutting notches of the tool. will
..1ps_oft_the_tooth_ surface being_machined.___The_basio_dramback-of--shaT
ex design of the tool (this shaver).
6
8
10
12-
14
16 --
18__
20__
22__
24-_
2.__
The "Romnomolets" factory produces mkchinos
Fig.204 - Diagram
of Operation of
the Rack Shaver
_
Fig.205 - Diagram
of Operation of
the Wheel Shaver
in which the cutting tool is a
.shaver representing a toothed
wheel with transverse notches.
In this case, the axes of the
wheel being machined and of the
shaver intersect (Fig.205). The
process of cutting is analogous
to that described above. The
shaver revolves, while the wheel
being machined moves .horizontally
(axial motion) and vertically to
28?
_to insure its being drawn toward the shaver. As practice has shown, shaving done by
30_1 this method can assure good surface finish and can provide the necessary accuracy:
32:]8 microns in the profile, 8 microns in the pitch, 5 microns in the eccentricity.
34:1
For shaving fine-module wheels, a sp4Scial machine design is in existence, in
36:]
_which the axis of the round shaver and the axis of the wheel being machined are
3
--placed parallel to each other in a horizontal plane. The ZSh-1 machine (of NII ESP
40_1 and NATI design) belongs to this type (see Bib1.1).
427q
IAERIng. The lapping method consists of machining the gear wheels by means of
44_4artificial intensified wear of the teeth, with the help of a lap (usually made of
46_4
_fine-grain cast iron) and an abrasive.
48?
On "Komsomolets" machines (model 573) lapping is done in the following manner
50-
--(Fig.206). The two laps (1) and (2) have helical teeth which, in touching the
52-1
?.straight teeth of the wheel being machined (4), created a worm-type transmission
54 1
--114hich is conducive to uniformamear, profile-,wise, of the teeth. The wheel revolves
56 i
-45-
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?
0
in engagement with three laps; the axes o the first two laps intersect in space
2-4rith theLaxis_ot_the_wheel,_while.the axis_of_the third 12p43)_ia_patasile.1 to it
4
6
10
12-
14
16 ?
18_-
20-
22_
The Wheel being machined, in addition to rotating, has a reciprocating notion. The
24_
laps are entrained toward the wheel under
Fig.206 - Diagram of Tooth Lapping
on a rKonsonoleteLtype Machine
some pressure.
11
Fig.207 - Diagram. of Tooth
Lapping
? 26__ In other machines (Fig.207), slaw revolution of the lap and of the toothed
?
23 wheel and rapid reciprocating motion of the lap (up and down) and of the wheel in a
30 radial direction are used.
32 According to the data of experiments conducted in the ENI, lapping assures
34 the following accuracy:
36 in wobbling 0.01 - 0.03 nm
3 in pitch 0.01 mm
40 in profile 0.005 - 0.010 am
4/__ After lapping, the side surface is highly polished, with a mirror-like sheen;
44?its quality is much superior to that of a ground surface. One drawback of lapping
46:dis the presence of abrasive grains on the surface of the teeth, which cannot be re-
48=Jmnved by washing and which cause premature wear of the teeth.
50-1 Grinding. The tooth-grinding method, in spite of many advantages (formation of
5=la theoretically correct profile with great accuracy, high-quality surface finish),
54:14-not-used-in-aircraft-instrument construction in view of the- fact
dp56_ umber-of-parts-of-aircraft instruments are made of nonferrous metals.--In-additiony
I STAT
1 I
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....??????? 1.4.1141......0%11....????????????
0 .
because of the small modules and the Rmali bulk of the gearwheels, this method is
2
melatirely_unproductive
6-1
8
10--
12--
14_-
16--
18__
22:1
24:]
26:d
28:1
30__
32_-
34
36
3
40
4
Rolling of gearwheels. Recently, w have started using a new method for pro-
:1 ducing cylindrical gearwheels, namely a Tolling process (Fig.208).
The blanks of the wheels being machined (1) are placed on the arbor a few at a
Fig.208 - Diagram
for
1
Tooth Production
by the Rolling Method
time, and the arbor is mounted to the
centers of a moving chuck (2). The
index plate (3) is set on the same
arbor. When the chuck is moved hori-
zontally, the index plate engages the
operating shafts (4), which, on fUr-
ther travel of the chuck, come into
contact with the blank and perform
the rolling process. The operating
shafts are gearwheels with a correct-
ed tooth profile and are equipped
with a tapered intake at one end.
The shafts .are forced to rotate
in one and the same direction and are
spaced at a definite distance, corre-
sponding to the dimensions of the
?wheel being machined.
44:d The tooth-rolling method cin be used in producing gear wheels with a module of
461
- 1 mm, including gearwheels of brass, bronze, hard aluminum, and steel. In
48:d the latter case, the blanks must be heated to t = 600 - 700?C.
50
Thetooth-rolling method assures high productivity.
52--
56-1
STAT
?
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
of teeth is analogous to the production o
6 414Lanke for_cylindrical-gear_wheels. eacutt%ng is done_on,gear--planerig-17-the-----
8:d rolling method. On a machine of such
10 . type, gear planing is done by two.
121 - _ ters (Fig.209), simultaneously on bot
?
14J sides. The wheel being cut is coa-
1 i
,_ _
16- - - 1 stantly engaged with an imaginary flat
" Fig.209 - Cutter for Cutting Teeth
18_ wheel and, executing a rotary motion
on a Bevel Wheel
20_ about the axis of the flat wheel, si-
--
22 ? 7mu1taneous1y rotates about its own axis. In this way, for each double ruing of the
? 24:1_ "awing bolster", the tooth is machined on'both sides (Fig.210). The time for ma-
26
Position 1 Positiors 4
Position 2 Position 5
CZZO
Position Positton!
--4chining the wheel is equal to the number of teeth of the wheel, multiplied by the
52--1
54?tiro for one double swing of the "swing bolster" of the machine.
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0
module wheel is 2 - 10 sea.
2
I In evel_wheels,_as_in_gearEheels, the chief_elementa_determiziii3g-tli&-quality-
4
of the gearing are pitch, profile, and concentricity of the teeth.
6
81 In large-scale production, checking he gear wheel, meehingwith standard
_wheels, is done on a special device (Figail). The arbor (2) whose center is pro-
10
_vided with teeth forming a rack, is set in the body of the device (1). The rack
12
meshes with a gearwheel (4) which, through the rotation of
14
the flyWheel (5) r ses or lowers the arbor (2) and the stand-
16
ard gearwheel (3) The gear wheel (8) which is being
18
checked is mounted on the shaft (7) in the stand (6). Hold
20
the wheel (3) with one hand, we turn the wheel (8).. The dif-
*22
ference in the readings of the indicator dial (9) shows the
24
amount of play in the side.
' 26
There are Gaviria" other instruments in existence for
28 Fig.212
checking bevel wheels (Bib1.2).
30
32 Worm Gears (Fig.212)
34
36
3
40
Blanks for tooth cutting are wnally prepared on turret or turning lathes.
Gear cutting is done on gear-cuttingmadhineswhiCh operate on the rolling
principle.
Unlike the hobbing cutters used for cutting cylindrical gears, the profile of
42......4
?.the
--the hobbing cutter used for cutting worm gears must accurately correspond to the
44:i I
profile and dimensions of the worm, which must be coupled with the worm gear with
46_1 1
--allowance for additional play at the top of the thread. For this reason the outside
48:i I
so_Idiameter of the hobbing cutter is 0.32 module larger than the outside diameter of
!
--Ithe worm. In this way, the overall height of the cutter tooth will be equal to
52--
54
7.16 module. When the tooth has this height, the cutter will also remove a chip
from the tops of thelrormwheel teeth. This is done to keep the periPhery of the
S TAT
?59?
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2
:I wcamlvhsel strictly concentric with its o4.461wi1 circumference. This method is also
_often_used_for_the_parts discussed_above__ rdnionst_sectors,_geara)
4_
The machine time in cutting worm gears is computed in accordance with the
6
_formals
8
12-
14-
16 ?
18_
20_
22_
24
26_,
T_ =3mx
- sill'
(13..6)
where Tm is the machine time, in min;
in is the module of the wheel being cut;
z is the number of teeth of the wheel being cut;
? is the radial transmission, blunt, for one revolution of the wheel;
n is the rpm of the cutter;
i is the number of settings.
. .
. -
- .'4. ? ?%
? . t , . ?
\1 \7
?
I
30_1 I % % '
i 1
--
s
I
ii 1
/
the cutter, which in this case depends on .
/
N.,: .. ,e,#-
the different curvature in the radii of the
36:: 1 I
outside and inside diameters of the hobbing
38__ Fig.213 - Diagram of the Notching
71
cutter (Fig.213), makes up 25% of the height
40__ by a Hobbing Cutter i
1
of the tooth. Consequently, the length of
42:: 1
the cutter path, counting the notching, is equal to 2.7 174 In addition, after the
44:1 1
i
--cutter has penetrated to the rated depth, when the radial transmission is discon-
46.d i
--nected, the worm gear being machined must be rotated through one or two full turns;
48:d I
then, the cutter path can be assumed as equal to--3 7/4
50? i
After gear cutting, the worm gears are checked for wobble and meshing. The
,
--accuracy of meshing is checked on special devices, by coupling the gear with a model,
. 54
The cutter path during the machining of
a worm gear is determined from the following
data: The normal height of a tooth is equal
to 2.166 in; the amount of notching done by
?worm.
56
STAT
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-
-iNoncircular Gear Irleels
2 --
.._...
6 ::::ittethreen_parallel_ axea_witturarlable _ gear_ratio. Until neoently.?_no_sufficiently.
32.1liable aid simple methods for cutting teeth into noncircular wheels were available,
101 which greatly interfered with their widespread use in instrument construction. By
nw, several methods for cutting noncircular gear wheels have been worked out
1411 (Bib1.3). Let us examine the method of cutting noncircular wheels on the Linotype"
16 -----Imachine (Fig.2:14). This method is used. for producing wheels with a smal1. module and
1
18=-1 short tooth lengths. The ring cutter (5); rotated by an electric motor, is used as
I
2011the tool. The noncircular former (1) and ;the plane former (2) are linked by a steel
22=band. By means of the handle (7), the noncircular former can rotate about its
Noncircular (cylindrical) gear wheeLi are used for transmitting rotary motion
24? axis 0202 and, together with the cleat (8), about the axis 00.
26
42
44
46
48-1
Fig.214 - Diagram of Machine for Gutting Teeth into
Noncircular Gear Wheels
When the former (1) rotates, the steel tape unwinds, and the plane former (2)
vet; in the direction of the axis of the ring cutter (5). The counterpoise (9) en-
5 50
? --sures continuous contact of the formers (1) and (2). When the plane former (2) is
2-1
--moving, it entrains the axis 05 of the pantograph (3). The stationary axis 0.3 of
54
56-1the pantograph is mounted to the hollow shaft (6).
STAT
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-1 Men the former (2) is moving, by means of the axis 04 of the pantograph, the
2-/
'Ax:Lal_displacements are_transmitted_to_the_shaft_(10)_of-the-ring-cutter.--The-rata-
4_4
-J, of displacement of this shaft to that of re plane former (2) is at the same ratio
6i
_ as the rates of displacement of the pantograrhts arms 0304 and 0305. The former (i)
8--
- is designed in accordance with the curve transformed according to the ratio of the
10-
- wheel to the centroid (4). The transformed curve is obtained from the centroid, on
12-
_ multiplying the radii by the constant quantity M. The axes of the blank (4) and the
14_
- former (2) are linked by a band and disks of different diameters. Consequently,
16 --I
_when the former (1) rotates about the axis 02, the blank (4) rotates about the axis
18_
_ 01 with the same angular velocity. At the same time, the blank (4.) rotates about
20_
the axis 0, together with the cleat (8), so that
22_
24-
001
? 26_
28-- The relative motion of the former (1) consists in rolling along the plane of
30- the former (2). The relative motion of the wheel being cut must be a rolling motion
32_ dueto its centroid, along the genetrix of the dividing cylinder of the ring cutter.
34.1
3. Analysis for Accuracy in the Production of Toothed Gearings
36
3 8 Let us examine the basic errors in the production of toothed gearings.
40
--Eccentricity in the Teeth
42__
44_1 The error of eccentricity causes the gear wheel to rotate, in production, about
4.-one center while the mechanism works about another center whose distance from the
48ifirst one is the amount of eccentricity. In addition to angular error, eccentricity
5?-lin the wheel causes a pu.lsating noise with periodically decreasing and increasing
52-
-
intensity. This phenomenon is most typical of high-speed gear transmissions (for
54 - example-i-gear-transmission- of a tachometer).
56
?
Eccentricity-in gear is by the fo31owing techno1ogica3.--factors:-
?
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12
?amount of eccentricity produced by the presence of play between the fitting diameter
__of the arbor and the aperture in the vb.ee
16--
Given:
18__
a) Wobble in the arbor or the driving centers on which the gear wheel (pinion'
in_being cut;
b) Play between the fitting diameter of the arbor and the aperture in the
wriuma;
c) Deformation of the machine - part - tool flexible system, etc.
10
E5crermole. In cutting a gear wheel on an arbor, determine the maximum possible
20_
22
It is quite obvious that the maximum amount of eccentricity is equal to one
daft =2,8_0.004;
dit.2 8+0,01.
1-
24
__Aalf the play:
26 I
2
-- here e is the eccentricity;
32
34
36
3
40
42.: ie diminished by:
44 a) More rigid tolerance along the inside diameter of the wheel blank;
46 11) Using a set of arbors;
48
smag
emAxisc 2
max is the the maximum amount of play;
2,810-2,796
epnax= .0,007.
1 2
It is evident from the example that the amount of eccentricity in the teeth can
50
c) More rigid tolerance for the production of arbors.
Wobble
52--
???=1M1
54- The-error-of--end-wobble of teeth results from the fact that-the axis-of-t
56--iperture-at-Whose-base-the teeth are-cut is not perpendicular-to-the support-face
STAT
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the arbor. This skewing may be the resui4 of inaccuracies in the production of the
2
wheel_ana_arbor_blankaa.
4
6 43rofile _Error
8
In addition to angular error in the wheel, a profile error in the cutter teeth
10
causes rapid wear and rough transmission. The basic technological causes of profile
12
error are:
14
a) Theoretical errors inherent in the tooth cutting method;
16
b) Inaccuracy in execution of the cutter profile;
18
c) Wobble in the cutter;
20
d) NOnradial front face, etc.
Let us examine some of these errors in more detail.
In cutting with a module cutter, an error in profile may be caused by the fact
__that the cutter number does not correspond to the number of teeth on the wheel being
cut. This error may be classified as theoretical, since it is the result of the in-
tentional use of an approximated scheme o) machining.
For calculating the maximum tooth-profile error when a set of cutters is used,
22_
28-
30_
32_,
34:1 --it is convenient to use the data worked out by Cand. of Tech. Sci. V.A.Shilihkar
36
Since, as a rule, only pinions with up to 20 or 22 teeth are cut by the dupli-
3
40
--eating method, we have given the values of coefficients up to that number.
42
44
46_
48--
50-
52--
-iformula
56-1
x
12
13
14
15
16
17
18
19
20
21
22
Ar
0
18
35
55
70
84
97
110
122
133
142
The greatest profile error Ar (in microns) is determined according to the
AT=iT _AT
Si
-4-
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0
2
???????!??????????.....????????????????????
1 where m is the wheel module, in mm;
4-
6J
8
10
12 ?
fthe tdbdlar_coeficient.correspamibagto_lLnuthber_ofteet_o_the-kheel
being cut;
Ar is the tabular coefficient corres nding to the number of teeth for which
'2
the cutter is accurately profiled
An error due to inaccuracy in the nodule cutter profile is copied in full (wit
a reversed sign) on the teeth of the wheel being cut.
In first approximation, we can estimate that the probable total error Arin the,
profile will be equal to
?._
I
1/0 1
i A z==911-Fm r , (I1.8)
I
?where Ofi is the tolerance for the profil; of the cutter teeth.
24-- I
_ Ifs must note that irradiality in the front face will cause an additional error
I
.26_
_in the involute section of the tooth profile.
28--
In cutting teeth with a habing cutter, theoretical errors result frouLthe fact
30--
__that the cutter-profiling process is interrupted. As a result, the profile of the
32:itooth, in the *end face, represents a broken line which osculates the theoretical in-
,
34_1
-Jvolute curve.
36
The nuthber of straight-line sections is equal to (Bib1.5)
3
1 40 I sk
I X '
I: !
42
44?where e is the duration of meshing;
46.71 k is the number of cutter teeth;
48-- zi is the number of cutter settings.
50? The length of these sections (Fig.215) is equal to P111, where Piz the radius of
52:Turvature at a given point of the ideal profile.
'
:1 -1
54-1-----The-limiting-value-is determined (Fig.216)-as-followsl
56 -----
STAT
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14 --
16 ?
18__
22_-
24
26
28
30
32
34
36
involute curve remains constant, i. e., P
negligible error.
= const. This assumption results in a
Expmading the value cos ---V
into a series, and restricting the calculation to
2
the zero and first members of the series, we will obtain
Fig.215 Fig.216
40 a) Theoretical profile; b) Actual
42 profile
44
Substituting the value of the cosine into the formula for the height of the
46
ridge, we will obtain
48
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0
21
4
6 'Then,
8
10
'VP
-
UtS?
p.
2 eV
(31.9)
12 The maximum error will be along the ircumference of the protusions. The value
__ I
16 1 Ms
I pa= 7', tg a,==--- cos ci4 tig so
I 2
14 is
18
20 where the subscript a is the point of the
22 protusions.
24 Consequently,
26
28-
30
profile lying on the circumference of the
0.21m
Ye ? ?4te cos aal tg se
32
In turn,
lo ? 114
COS2e-
COS at=
R
?
s+
34
-
1
36
In the above equations, z is the number of teeth of the wheel being milled;
38-1
-1 a is the profile angle of the initial contour.
40_
44_
Wobble in the module and hobbing cutter also leads to distortion in the profile
of the gear.
In the rolling method, as a result of wobble, the axis of rotation of the hobb-
--ing cutter will intersect the axis of its base cylinder. In this case, if there are
=To other inaccuracies in the tool, the cutting faces will be displaced from their
50
?correct position on the gearing line. Depending on the angle of rotation of the
52--
--cutter, these displacements vary in accordance with the sine law. The extent of
54
--displacement (Af) is determined by the formula
STAT'
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sm.m1
4_
Alf= t1 sin adsin
6 ___wheretii_ilit_the_paranel-ditsplacement_of_.he Amds nfthe_baseLcylinder re1Atimoto__
8:d
10-
22_
the axis of rotation of the cutter;
(pi is the angle of rotation of the iutter.
The displacement of the cutter varies within the limits
tf,= ? sin ea and -- L singe
Consequently, the error in profile is equal to the algebraic difference
Ltfinax frnvr2Lthn crii. _J (11.11)
An error in the forming of teeth is caused by incorrect setting of the cutter
26-1_ and by ervi wobble of the cutter.
28-- The correct setting of the cutter depends to a large extent on the experience
30__ of the adjuster. End wobble of the cutter depends chiefly on the accuracy of the
39__ cutter construction. For first-class hobbing cutters, the end wobble must not ax-
34--coed 0.005 Unli
36_
--Pitch Error
Pitch error is mostly caused by kinematic inaccuracies in. the machine. The ac-
42_I curacy of a machine working on the duplicating principle is determined by the scat,.
I
44 iracy of execution of the angular pitch of a dividing disk, by the concentricity of
I
46.--lit s fit on the spindle, and also by the wobble of the front drive center.
I
48__ The accuracy in manufacturing the dividing disk should be such that the total
..._, i
5a71 error in the wheel being cut will be within the limits of 5 min on the full revoln,.
7.] 1
5,11 jtion of the wheel, and that the error in the individual pitch lies within the limitsi
i
-1I i
perate on the rolling principle, the greatest-inaccuracies ?
1 STATI
_ASIR_
I
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are of the kinematic type which cause a alsruption in the correlation of the magni-
4.12:2201WA=CRIP
2
J...tude_of_inotion,...or_rate of. _motion,of theicomponent links of It Treirhinn t * a
4_1
lack of coordination of the reciprocal movements of the parts of a machine. In the
rolling method, the angular inaccuracy is 30 - 500.
8-1
Inaccuracies which depend on the rigidity of the machine have large magn.itudes.
HSpecial research (e. g., see Bib1.5) has been devoted to establishing analytical de-
1 0
12
pendences which express the effect of inaccuracy in individual parts of a machine on
14
the accuracy of execution of the wheels being cut. We must note that, in the roll-
16
ling method, any inaccuracy in the cutter profile causes a quite definite error in
18
the pitch of the wheel being cut.
20
From Fig.23.6 it follows that the error in pitch of the wheel being cut will be
22_
24?
.
26-
28-
30
equal to
Ate-- nm [cos ad? cos (ad ? Acta)J entLted sin ed .
In conclusion, let us note that .in this Section on3y some basic technological
causes of production error in machining w44e discussed. In addition, the technolog-
32_
__Jail process of assembly causes several other, no less important errors. These
34_H --pwoblems are examined below*.
36
3
40_1
42_
?2.
BIBLIOGRAPHI
Bozlov, N.P. - Fine-Module Gear Transmissions. Oborongie (1949)
Pimkin, N.V. - Measuring of Gear Wheels. ONTI (1935)
3. Litvin, F.L. - Noncircular Gear Wheeli. Mashgiz (1950)
46.-
-11.? Shishkov, V.A. - The Gear Cutter Catalog. EMS (1944)
48
? --5.
50?
System of Regulating Gear Wheels.. STAMEN (1943)
Tayts, B.A. - Inaccuracies in Gear Milling by the Generating Method, and the
? 54 -46--See -Chapter-XVII - Technology of the -Production -of Specia3: and-Assembly-of
56 _ Trt etruments -with-Flexible-Pickup- Elements.
69
S TAT
1
r?1
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J.,?;???
8 ?4
14--
16--
20_
_1. General Principles .
22?
CHAPTE2 XVIII
1
TECHNOLOGY FOR THE PRODUCTION OF SPECIAL PARTS AND
ASSEMBLY OF GYROSCOPIC INSTRUMENTS
24? The most widespread gyroscopic aircraft instruments include the gyro turn irk-
96_dicator, the gyro horizon, the directional gyro and the gyromagnetic compass.
28? Gyroscopic Instruments operate under difficult conditions; vibrations reach 80
30_ cycles, with an amplitude of up to 0.15 i4; when the aircraft is laneing, the in-
32_istruments are subject to considerable impacts and jars; the temperature range at
34-1which an instrument must operate extends from +50 to -60?C.
36
40_
42_
44_,
--12. Characteristics of Some Gyroscopic Instruments
46..
The following requirements apply to gyroscopic instruments:
a) Accuracy of readings in rectilinear flight;
ti) Stability in maneuvers of the aircraft;
c) Reliability in constant use.
48_ The basic part of all gyroscopic instruments is a rapidly rotating rotor mount-
50--ed on gimbals. Rotation of the rotor is accomplidhed pneumatically or electrically.
51 Pneumatic gyro instruments operate at a pressure variation of 40 - 50 =fig
? 54:21(gyro-turnindicator)-and 80-- 90 mai Hg (gyro 'romagnetic
?Depending-upon-what instrument-is being,ased,-the-air-consumptdon----
STAT
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varies within considerably wide limits. or example, in some series-produced instru
2
Jments_the_air _1
_consumption_is8 -__20 ltrimin_for_the_gyro_turn-indicator,-
4_1
- 60.1tr/min for the gyromagnetic compiss, and 60 - 65 ltrimin for the gyro
?
6
81_1horizon.
The moment of inertia of the gyro rotor for each of these instruments is as fol*
10--
J = 0.6 gm*cm-see2 for the gyro turn indicator; J = 0.7 gm,.cm-sec2 for the di-
12_
rectional gyro; J = 0.9 gincm-see2 for th gyro horizon, and Ji1gm-cm-sec2 for the
14__
__gyromignetic compass.
16--
The rate of rotation of the gyro rotor is n = 6000 - 8000 rpm for the gyro turn
18_1
__indicator; n = 10,000 - 12,000 rpm for the directional gyro and the gyromagnetic c
20__d
pass; and n 10,000 - 15,000 rpm for the gyro horizon. In electric gyroscopic in
22_4
--Istruments the rotor speed is as high as 2.3,000 or 23,500 rpm.
24.1
There are high requirements as to quality oethe bearings of gyroscopic instm-
26__
_.-ments. The moment of friction in the beatings of the gimbals of a gyro horizon =At
20-1 --not exceed 0.3 - 0.5 gm-cm; in the directional gyro it must not exceed
___ 0.2 - 0.3 goi-cm-
32__
The dead angle in the instruments (gyro turn indicator, gyro horizon and gyro-
34__
?magnetic compass) must not exceed ?3.0.
36HThe rotor of gyroscopic instruments must be statically and dynamically well .
3
balanced.
40
The axes of the gimbal assembly must intersect in one point at a 90? angle.
42
The individual units of gyroscopic instruacnts must be balanced in relation to
44:1
--the axes of rotation of the instruments.
45_
The housings and air ducts must be airtight.
48?
In the case of electric gyroscopic instruments, special attention is given to
50-1
? --the insulation resistance and to the reliability of current feed.
52-7
5471 Accuracy of operation of gyroscopic instruments is largely determined by the
56?quality of production of the gimbal assembly (coaxiality of the gimbal parts, mini-
STAT
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-
--Imum friction in the supports, and balance of units and parts relative to the axis o
irotatioU).___In_the_follow-ing,..we_will_examine_the_technological_processes_for-making
2
4_j
6the basic parts and units and for assembling the gyroscopic instruments.
8d3. Axles and Cups of Bearings
??????
10?
Accuracy of instrument readings and mechanical strength of the instrument de-
pend to a large extent on the quality of manufacture axles and cups of the bearings.
14
_]At overloads, the forces of inertia are absorbed directly by the instrument axles
16--
__and ball bearings; for this reason, higher requirements as to resistance apply to
12-
18
20__
22_
24__
these parts.
Tables 44 and 45 show several types of axles and cups for bearings of gyro-
scopic instruments as well as the corresponding requirements.
The basic indexes of the quality of axles and cups are:
26_
1) Accuracy of dimensions;
28_
2) Correctness of geometric form;
30_
3) Smoothness of working and fitting surfaces;
32_
4) Mechanical strength;
34-
5) Basic structure of the material.
36
Brand ShKh15 steel is used as material for axles and cups.
3
The basic structure of ShKh15 steel must be fine-grain pearlite, with evenly
40
__distributed fine carbides. The structure must be uniform. When the structure is
42_1 irregular, the mechanical strength of the working surface after heat-treatment will
44_
--vary, resulting in rapid wear of the axles and cups. The permissible content of
nonmetal elements and carbide liquations is indicated in the technological specifi-
48_1
'cations. Carbide particles possess great hardness and brittleness (800 Brinell
50 1
_tunits). In the process of machining, the carbides may bloom to the working surface;
52-1
--like nonmetal elements, carbides stain easily, and like them, create centers of de-
54
-Jstruction in the working surface and increase friction. At uniform structure, the
56 t
1
STAT
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--------------
4:
6
10 ?
12
14_
16 ?
18 _
20_
22_
24?
_
26
28-
30-
-
32.?
_
34_
36_
3
Rasic_Requirearnts
40
42
44
46
48:
50-
52-
541
Ground thread
1. Wobble in the thread relative to
the surface d not more than 0.05 nin
2. Out-of-round of d, not more than
0.04 En
3. End wobble, not more than 0.01 m
_
cvs iwwW
Ground thread
1. Wobble in the cone relative to
the thread, not more than 0.05
2. Out-of-true of the cone, not more
than 0.02
13. Tight thread
W5/7R47NOV
vim 8
? 1. Cone wobble relative to D, not
more than 0.01 nin
2. Out-of-true of cone, not more
than 0.003 mm
W5 /w WW1 /
vciv
Vil4i112
1. Wobble of the ball race R relative
to D, not more than 0.02
2. Out-of-round of the profile of the
ball race, not more than 0.003 mm
_
STAT
?73-
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_or--
44
Iv
8-
10
12
14
16 ?
18 _
20
22
24
Basic
II
vq5/ wv8pcw/2/
cl 1. End wobble ab relative to D, not
mor than 0.015 nn
2. Cone wobble relative to D, not sore
thrill 0.02
3. Out-of-true of the cone, not xtrwe
than 0.02 NU
46?
cP75/ vixl,www
Cup
cv.7 AvvRivvcrga/
1. Wobble of the surface d relative
to the surface D, not more than 0.0032 ma
2. End wobble ab relative to d, not
morel than 0.01 ma
Table 145
Basic Requirements
1. Wobble of the surface d relative
to the surface D, not more than 0.03 ma
2. Out-of-round of surface d, not
more than 0.06 ma
3. End wobble oh relative to the aids
of the part, not more than 0.015 ma
STAT
)1 1
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ws /v778, cv771Z/
24--
-
" 26-,
28 --
30_-
1. Wobble of the surface .d relative
to D, not more than 0.006 ma
2. Out-of-round of the surface d,
not more than 0.003 nza
3. Outer end wobble relative to D,
not more than 0.01mm
4. Side wobble of the surface d, not
more than 0.025 nu
5. Taper of the surface D, not more
than 0.003 ma
1. Wobble of the surface d relative
to the cone, not more than 0.015 met
2. Out-of-round of the surface d,
not more than 0.005 in
3. End wobble oh relative to the
cone, not moi.e than 0.02 11111
4. Side wobble of the surface d, not
ri than 0.01 Da
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0
4_
Tab12_45
Cup
Ba.sio_Re quirement8
17
1. Wobble of the surface d relative
to D not more than 0.01 xmi
2. Out-of-round of d, not more than
18_ 3. End wobble relative to D, not
20- mere than 0.01am
22_
24-hardness of the axles and cups should. be 62? 65 R.0.
26_ The temperature of heating for hardening of ShKh 15 steel is 825 - 840?C, and
28 -Hquenching is done in oil. After.hardening, the steel must be tempered to eldndn te
30_ internalstresses. The best procedure foT tempering is heating to 150?C with aging
32for 2- /Flora.
34_ To obtain stable dimensions and to eliminate waste due to deformation of axles
36 andcups, artificial aging at a temperature of 125 - 130?C, with holding for 10 bra
3 is used.
40 In electric gyro instruments, bearings with inner races are used; for this r
42 son axles for these instruments differ somewhat from axles for pneumatic instrumental.
44 Table 46 lists several types of axle l for electric gyroscopic instruments. Thel
46-basic distinction between these axles and !the axles examined above (see Table 44)
1
43-lies in the fact that they do not touch the bearing balls but are joined to its in,.
5t]ternal ring. This group of axles is made'fromEn4 steel and is not subjected to
1
5:lheat treatment. In electric gyroscopic instruments, the frames have thin walls,
1
54-jdue-to-the-absence-of-air ducts; for this reasons-fixation of-the-axlesi-except-fori
a6
r-----ls-done--also-by-the-ends.- In this connection, the base-ends-of-the-4--
i STAT
.????.d
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??????????????111110
0
OM.
2?
111??????11
8-
10
12?
Axles of___Electric InstrNments
Basic Requirements
24?
_
26?
34
36
3
40
42
44
1. Wobble of the surface D relative
to I, not more than 0.005 BEI
2. RA wobble AA relative to the
axle, not more than 0.01 =
1. Wobble of the surface D relative
to 11, not more than 0.005 ma
2. Wobble of d2 relative to di., not
more than 0.1 Bit
3. Wobble of the cone relative to
d not more than 0.01 me
10
4. End wobble AA relative to the
axle, not more than 0.01 us
,0,,ezzt.
46
48
R B
50
5
54
56
1. Wobble of the surface d relative
1
o iz2, not more than 0.02 am _-
2. Wobble of d3 relative to d2' not
more than 0.04 =
3. End wobble AA and BB relative to
the axle, not more than 0.02 me
4. Part surfaces in contact with
wires must be coated with a layer of BF-4
-adhesive
STAT
r-ff
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1
? 0
-iaxles must be strictly perpendicular to tile geometric axis of the part. Since the
2--
?.?working_surfaces_of these_axles..do_not_foia.racewaya_for_the ballet.r_ammmdiat_lower___
41
_Jrequiremnts for smoothness in machining apply to them. Some axles have apertures
? 6
_for current leads. In this case, the axle surfaces in contact with the current
8--
_leads, are coated with a layer of BF-4 adhesive, for better insulation.
10--
12. Machining the Axle of the Gyro Rotor for Pneumatic Gyro Instruments
14]
The axle of a gyro rotor is turned ork turret lathes or on automatic horizontal
16--
lathes. After turning, the rotor is subjected to heat-treatment and then to grind-
_ ing. The grinding must be done with special 'care; rough grain, burns, ellipticity,
18_
20_
?
and conicity are not permissible.
22?
-'3.97
zh4
a)
28?
.
30
32
34
36
3
40
?5-0
b)
35C5
-4-
5,5-oil
Fig.347 - Axle of the Gyro Rotor
a)
a) Dull to R0.2; b) Finish to a glasslike surface
42__ In grinding the cylindrical surface of an axle on a base of honed cones, the
44--center of the back face must not touch the part at points of the raceway, which
4night result in damage to the parts.
48? Grinding the ends may be done on a circular grinding machine, or on a surface
5?--Igrinding machine. In the latter case, the process is considerably more productive
-1
52.7.1and no special devices are required.
54 1 To-obtain-the-required surface smoothness of an axle-cone, ipilishinvis-used. 1
c-
----1Polishing-does -not-eliminate the inaccuracies in geometric form-which-had-occurred?I
? STAT
_241_
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h)I
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0
- _ - - - - -
- - - -
in the previous machining process but on.1,4 improves the smoothness of the surface.
polilhing_the axles_is.dons on a drillingLachinspecial 121p (Fig..340.--
2
4_The lap is made of brass; the working surfaces of the lap are clad, with a layer of
6
8-J
10 -
12-
14_
16--
18_
20_
22::
24--
26_-
28_-
3
1 In polishing an axle, wobbling of th machine spindle must be avoided; the ma,
chine table must be perpendicular to the spindle. A recipro-
cating motion, witlin the limits of elasticity of the split
end,- is transmitted to the lap; at this, the rotational -speed
of the spindle is equal to 1400 - 1600 rpm. The polishing is
done with GOI pasJ. After polishing, the surface should cor
respond to, -N71177 12. Checking the surface is done on a
Linnick microinterferometer. With it, the following defects
can be discovered:1
a) Scratches produced by dirt dropping into the paste;
b) NOnuniforrmidth of polishing in the raceway,
caused by noncoaxiality and skew of the lap;
c) asessive undulation as a resat of using a burnt,
I
hardened abrasive.
I
After the final machining the parts should be lubricated
with nonacid oil to protect them from corrosion.
Fig.348 - Lap for
the Gyro Rotor
Axle
40
42__ chining the Bearing Cup
44:1 Bearing cups are rolled (Fig.349) on turning or automatic turret lathes. Grind
46=1
--Ing the ends may be done on a lapping machine or on surface-grinding machines. For
48
--grinding along the outside diameter, centerless grinding machines are used, while
50--
-in
ternal grinding of the raceway is done on a special spherical grinding machine.
5
In grinding the raceway, the bearing cup is clamped in a special diaphragm
54_7_
56..Jh
uck, shown in Fig.350.
-79-
S TAT,
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0
2
6
8
10
_bosses_(3).,_to_which_three_clamping
The flange of the chuck:body (1) car ies the diaphragm (2) with three soldered
???
cams_ 5Lare_fastened_w1th_the_serzws_44)._By?
means of the rod (6) passing through the hollow
spindle of the stock, the diaphragm
can be bent; in this position, the cams
separate (see the lower projection in
Fig.350), and the part to be machined can
be easily inserted into the chuck. When
the rod is pulled back, the diaphragm straightens, the cams make contact and clamp
.
12=1 _the cup being machined. The working surfaces of the cams of this chuck are ground
14_
16--
__way with respect to the outside diameter.
18_
after the chuck is placed on the machine, Which results in concentricity of the race.
20_
22_-
24--
26 ?
28--
30?
Fig.349 - Thei Bearing Cup
32 a) Polish; b) Finish to a glasslike surface; c) Facet 0.2 x 45?;
34 d) DUI1 to R = 0 1 02; 4Maximum. end wobble relative to 016G
-*--0.
36 mmst be 0.01 ?
3
The raceways in a bearing cup are polished on a lathe with the special lap ii-
40
_Ilustrated in Fig.351. A tinned lap and 601 - 120' emery powder are used for prelim.
42_1
polishing; machine oil is used as tlie lubricating fluid.
44_
46_
--The profile of the raceway is checked from an impression, taken by pouring a fusible
48-1
?alloy into the raceway; the checking is chine on a projector which enlarges 100 times,
50:1
A palm lap and GOI paste are used for burnishing, with kerosene as lubricant.
Rotors
54
56
The rotor is one of the basic parts of gyroscopic instruments. In producing
STAT
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0
the rotor, extra care is required, since even insignificant imperfection in its bal
2
_ance_ge.nemates an_imuxiliary centrifugal..firce_which_places_a_heavy_loson he
4
bearings.
6
???? ?
10-
12
14
' 26?
_
28-
30_
32_
34
36
3 The material for the rotor must be uniform, without blowholes (a condition nec-
40 essary for good balance), sufficiently tough to withstand the considerable centri-
421 fugal forces which develop at high rotational speeds, and resistant to corrosion; it
44_-mmat have a rather high specific gravity, to *obtain a high moment of inertia despite
46:Ismall dimensions.
48? Rotors are usually made of I959-1 brass, aluminium-nickel bronze, and stainless,
50? steel (the latter is rarely used, since it is difficult to machine).
52--
Technological Process for Rotor Manufacture
54.
567-1--4,559-I-steei-is -used in- manufacturing rotors (Fig.352)7,--- The blan1c7for -the-ro=i
Fig.350 - Diaphragm Chuck for
the Bearing Cup
Fig.351 - Lap for Polishing
the Bearing Cup
?
STAT
?
'
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STAT
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reM/VaiMalaliM4LIS
4-
6_
tor is obtained by drop-forging.
To_eliminate_internal_stresseswhicILmay_stbsequently_eause_marpdng-ofthe-rol.-
tor and lead to destruction of its balance, the forged blank is subjected to anneal-
and then to etching and washing.
10-- 244 C1178MPV877.5.77.30
49- ,
43
8?
?M?1?1.
24--
26?
. 28--
30__
3
40
c:?
441
65R
0-43
Fig.352- The Rotor Viewed from the Axle
Machining the rotor on a lathe consists of three stages and is done to obtain
minimum wobble of the outside diameter with respect to the inside diameter. In the
first stage, the basic Allowance is removed, and the aperture is drilled. In
ing, the rotor blank is clamped in the usual three-cam Chuck. In the second stage
of machining, in order to obtain high concentricity, the part is clamped in special
42_1
44:1 --bored simultaneously with the external rolling, which ensures its concentricity.
To obtain the necessary accuracy and optimum surface smoothness of the ap-
cams which are fastened on the usual cams of the chuck and are bored in situ.
Clamping in such cams does not deform the part to be machined. The aperture is
46.,
4 8.-
--erture, the aperture is reamed. To
50_1
?the reamer is fastened in the chuck
52-1
--and fed to the reamer. After this,
54
prevent the reamer from breaking the aperture,
of the machine, while the rotor is held by hand
the minim= allowance is ground off the external,
56_1
---,surface. The rolling is done on a precision lathe.
In this case, the rotor is na-
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0
-Ichined in one operation. The rotor is moilnted to a smooth arbor. To prevent wobble
e_arbor,_itAmustbe_bored.on_the_spoLConcentricity-in
4__
_tor is checked in the centers with an indicator gage. After the final lathing, the
6
.holes are milled on a vertical milling machine, with a special cutter. In mounting
8-1
_the rotor to the arbor, the same base is used as in lathing, which process ensures
10-
concentricity in the distribution of the holes. The holes must have the same dimen-
12
_4sions in depth and pitch, in order to avolivibrationsof the rotor when it is ?per-
14_J
ating in the instrument. To obtain holes of the same dimensions, the cutter must
16
rotatefor three to five seconds without feed after the feed has stopped. In mill-
18_
20_
22_
ing the holes, burrs are formed which are removed by rolling on the same machine and
in the same arbor as in the final lathing.
After this, the remaining negligible burrs of the holes are removed with a
24--
:lscraper. This completes the machining of:the rotor.
26
In transporting rotors, extreme care'is required since even small scratches are
28:1
--difficult to smoothen, due to the fact that the allowances removed in the last lath-
30_1
operation are negligible. For this reason, special packings with a separate
32_1
compartment for each part should be provided for storing and transporting rotors.-
34_
After press-fitting the axle, the rotor maybe nonconcentric relative to the
36_
---wornkig taper of the axle. For this reason, the rotor is again bored along the en-
38H
-tire surface, after press-fitting of the axle.
40:1 42- Technology of the Rotor Construction
44
The above-described rotor is being replaced at present by a more perfect de-
--sign in which the rotor is integral with its axle (Fig.353). The ends of this axle
1
-Jhave cut-outs into which, during assembly, a ball is inserted which replaces the
50-
--taper ends and raceway of the steel axle in the design of the first variant.
52--
54
56inological advantages: Assembly is simplified, since a spherical support is less
_?43_
Such a rotor design results in great accuracy of balance and has several tech-
STAT
5.2,
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
-116401....?????????
--sensitive to skews; repair is simplified, I since all that is required is exchange of
Ihe_ball; in mAchining, expensive_operatT nit lor-machining-the-taPer-ends-J3t-the-r?`
4-4
_ttor axle are eliminated. Thus, this kind of rotor is more economical to produce.
6
10
12 ?
14 _
16 ?
18 _
20_
92 _
2 --
4_1
26_1
28
30
32
34
36
40
The technological process of manufac uring a rotor of the second variant does
not differ in principle from manufacturing a rotor of the first variant; it is just
that machining an aperture for the stee
axle is replaced by machining the cone.
flanges. The basing in the final lath-
ing is also simplified, since instead
of a specially prepared arbor for each
. part, the machining is done in the cen-
ters. Producing a rotor of the second
variant is more economical, since there
_
(V.VC49, W4.'73)
254
Fig.353 - The Rotor with Axle
their form is changed.
42:]
--heads
44d
--42 teeth are mounted to the spindl
46_1
--the spindle by the index pin (5).
48--
The new form of
is no need for a steel akle, for assem-
bling it with the axle, or for boring
the rotor after it has been shrink-
fitted to the axle.
To increase the rotor efficiency,
the number of holes in the second vari-
ant is increased from 24 to 42, and
the holes requires the use of special index
1
(Fig..354). The index plate (2) with 42 divisions, and the worm wheel (3) with
1
e (1) of the head.
The index pin (5) is moved away from the index.
handle1(7). When the lever (6) rotates, the
50:: I ,
--sliding bar (8) and the pawl (9) start moving; as soon as the index pin (5) is no
plate (2) by the lever (6) and the
The housing (4) is mounted to
52?
--longer engaged with the index plate, the worm wheel turns the spindle one division.
54
'When pressure is released from the
5 handle, the spring (10) returns the sliding
6a
1,
STAT
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0
? bar (8) and the pawl to their original po ition and at the same time, through the
2
__.1.elmm_6L-acte_sma_this_indexpin45)--,--forcing_it_against_thm 4ndex_plato. nur4
__this, the housing (4) of the index pin re s on the stop (11).
6
The feed in this device is supplied lifting the handle (7). This causes the
housing (4) of the index pin, together will the spindle (since this is connected
8-n
_with it through the pin) to move away frol the stop (11). and drop by the required
10--
12--
- angle, until the adjustable stop screw ( ) rests against the stop (13).
14_
16?
.34 Fig.354 - Index Head for Milling the Holes of a Rotor
36
3
??????
54
The Frames of the Gimbals
The frames of gyroscopic instruments must satisfy rigid requirements with re-
spect to accuracy in the execution of the bores and in their distribution. Check
tests must be made, after the frame has been machined, to determine Whether
56-1
a) the two opposite bores are c
al;
b) the two intersecting axes are located in one plane;
1
c) the two axes intersect at an angle of 900;
1
d) the base ends are perpendicular to the basic axes of the frame (especi
in-the case-of electric gyroscopic instruments).
In machining-the-frames le pneumatic instruments, -we-must-provide-for-hermetie-
STAT
t
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
???
?..
-- sealing of the internal air ducts, and th re mast be no blowholes or brittle spots
4__
6?
8-
10
in the_material. This_is obtained_by pecepaning_the_bmnk_a_the_fmnes IT chill.,
casting or pressure-casting. (The frames
of electric gyroscopic instruments need
92
24
* 26
28
30
32
34
36 . Fig.3551- Frame
not satisfy any requirements as to hermet
c seal.)
3
p.
0
Alnnininmalloy is used in the production of the frames. AL6 and A108 alloys
- are used for chill-casting; brand AL3 alloy is used for pressure-casting. let us
42 I
__study the typical example of a technological process for producing the frames of the
40
44_
- ro horizon (Fig.355).
46_
The blank of the frame is chill-cast, after which the cast gates are cut off.
48-
--Aging is used to eliminate internal stresses. Internal stresses may cause warping
sol
--of the frame and loss of the accuracy attained in machining.
52--
After aging, the bores are subjected to preliminary drilling,which Allows bor-
54
6
--lingwith a smaller set of instruments. Subsequent operations are: sandblasting,
5
STAT
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0
? washing in gasoline, drying, and sealing the air duct with special gaskets. The
2-
-_gaskets_are_set_in_methanolic_adhesive._ Thi ais tollowed_by_caul1ing_the-duct_bead1-
4_1 ? and drying for 24 hrs. After completion, the frames are checked for hermetic seal
6
under a pressure of 200 mca Hg.
8
One of the basic stages in machining a frame is the preparation of the base
10-
- plane, in reference to which the holes will be bored. In machining the base plane,
12--
_ the frame clamped in the device mast not undergo elastic deformations, since it mar
14_
_ later straighten on removal of the clamping force, resulting in warping of the cor-
16?
- rectly machined base plane. Fixation and clamping to an uneven plane will eause the
18_
- same phenomena in the boring of holes.
2 0_
After preparing the base plane, the basic bores of the frame are made at a 900
.22_
_ angle. If the frame is subjected to elastic deformation under clamping, then even.
24?
i- n accurately executed bores the accuracy 'will be canceled as a result of warping of
26_the part after it is taken from the devicI.
28?
Let us show on a typical example the linaccuracies which may occur when the
30?
_frame is clamped incorrectly. In a device for milling a frame, the supporting aur-
32
faces AA of the frame and the direction of action of the clamping force P are shown
34L_
__schematically in Fig.356.
36
If we consider the frame as a beam supported freely at two points, the angle of
3
--rotation of the walls, in which the apertures are bored under the action of the ap-
40_
_plied load, may be determined from the formula'
42_
4 4_-
46-
48_1there P is the clamping force;
PL'
radians,
16E1
50? L is the distance between the supports;
52-- E is the modulus of elasticity;
O..,
54? I-ie-the -moment-of- inertia-of -the- section.
The-numerical value-of this error may be judged from the following-example:
561
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0 -
1 For simplicity of calculation, let us assume that the cross sections of the
2
. aflexihia_malls of_the frame_are rectangularizmard_h_n_25_,mm_in-each-wall,-
4?i6
making in all, b = 12 smand h = 25 mm. The clamping force is P = 200 kg; the die-
?tance between the supports is L = 100 mm. The modulus of elasticity for aluminum is
8-1
_itaken as equal to E ..., 72 x 104 kg/cm2. Under these conditions,
10
12
14
16
18 whisili corresponds to 0.001 x 3438 m 3.438
20
22
1,2.2,53 _1,56 cnt4;
12 12
PL' 200.10'
16E1 ? 16.72.104.1,56-0,001 radiaht,
24
26_
. 28
30
32
36
3
40
42
44_s
46-
Is 3.4 min.
Fig.1356
a) Frame clamped on the device; b) Frame taken off the device
48__ A skew of 3.4 min in a length of 50 =will be 0.05 mm, while the permissible
50?skew is 0.03 mm in a length of 50 mm.
52-- Such an error in machining the bores in frames cannot be Allowed; consequently,
54?in-devices for-preparing the base plane and boring the- apertures-,---roments-of-flemirei
56=lfrom-the-clamping-forces-must be prevented fram acting on the trante-i?lhis-can-be
STAT
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avoided if the action of the clamping forte is directed against the supports.
ring the_holes_in_the_frame_is_dammian a nniversal_rming rmcbine_or on an
aggregate machine. In machining on a mining machine, the frame is attached to the
6 i
table, and the replacement tools are inseited in the spindle of the machine. For
8 1
?undercutting the ends, a special arbor with knives is used. For boring the aper-
10-1
.J tures we use a special chuck inserted in the spindle of the machine and carrying the
12
Hboring cutter. This chuck provides for movement of the cutter in a radial direction
14?
_with the help of a micrometer screw. For preliminary machining of blind holes we
16--
__use special end xn117n which, unlike drills, do not lead off the aperture; this is
18
20
22
24
' 26
28
30
32
34
36
3
important to obtain an even allowance for
40
42__
44_-
467-
48_?
final boring.
Fig.357 - Diagram of an Aggregate Machine for Boring
1
Apertures in a Frame
Machining apertures in the frame of the gimbals on an aggregate machine is more
". 52-
-productive than on a milling machine. A diagram of such a machine is shown in
54
-,Fig.357. The machining is done in two operations from two settings. Advance of the
56
LI1
STAT
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?
0
tool is produced by each s Inn e in turn, since this operation is done by hand by a
2-4
minee worlosr
44
Fixation of the frame in the second setting is done in accordance with the pre-
bored apertures. Apertures in the frame Of the gimbals may also be bored on semi-
RJ
automatic machine groups, in this case feed for the power heads is supplied automat-
10--
ically. Correct distribution of the ape ures is checked on special devices. The
12?
device simplest in design is the following: A special large frame with accurately
placed apertures is prepared; the frame ti be checked is placed inside this frame;
14_
16--
__through four pairs of apertures in both fames, plugs are inserted; if the apertures
18?
__of these frames coincide these plugs should drop in readily. If a plug does' not
__pass through a certain pair of apertures, the frame is rejected. A device of this
22_
--type cannot check the distribution of the apertures within any definite tolerances,
24--
--since this will be affected by the tolerances of the apertures themselves, by inac-
.
26-
--curacy in the distribution of the apertur4s, and by elasticity of the frame. This
28_
--
method is not objective, since the plugs may be inserted with varying degrees of ef-
30_
--fort. The most perfect method of checking the distribution of apertures in the
__frame is with an indicator gage. To do this, we insert into the apertures of the
" frame special plugs with center apertures which are strictly concentric with the fit-
--ting diameters. There is a set of such plugs, down to 0.005 mm, for every aperture,
33--
--which simplifies selection of the plugs adcording to the diameter of the aperture,
which
may vary within the limits of 'the tolerance. The selected plugs are, inserted
42
into the apertures in a tight fit. The coaxiality of two opposite apertures is
44:1
--checked by setting the frame, with the inserted plugs, on the centers (Fig.351)*
46_
48--
Checking the perpendicularity of the ma's apertures is done on vertical centers
50--
CFig.359)*
Correct distribution of axle apertures in one plane is checked in the foliating
52-- 1
54--manner: Four plugs with the same size necks are inserted into the frame. The gen-
56 eratrixes of the necks of these plugs should lie in one Plane; this is checked on a
STAT
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Oa ???????? .10..????
1161.1.40,34144l*
.0
special plate, with which the necks of th4 plugs, with their generatrixes, should
2
coincide-
4_1
6-1 The correct distribution of aperturei in a frame should be checked with great
care, but should be checked only once.' en repeated measurements are taken, the
8
?plugs must be reinserted into the aperturls. Measuring two or three times may bring
10--
_the dimensions outside the limits of the tolerance, since the frame material is Pla
12?
tic so that the size of the aperture may easily enlarge.
14_
24?
' 26
28
30
_
-
32 Fig.358 ? Diagram for Checking the Fig.359 ? Diagram for Checking
34 Coaxiality of Frames on Horizontal . the Perpendicularity of Axial
36 Centers Frames on Vertical Centers
3
?
Subssqgent operations are: turning the bead to scale, which is done on the base
40
--of the bored apertures; drilling the apertures; threading; and milling the recess in
42 1
:ithe air duct from the bored aperture end. Threading for a center screw Is done by
44-
--hand, with a special tap having a guide which moves through a collar inserted in the
46
:ipposite aperture.
48_
--, After the final machining, the frame should be carefully cleaned of chip and
50? 1
2-1
7?washed in kerosene. No trace of chip or dirt mast remain in the air ducts of the
5
--frames. In the process of operating an instrument, a chip may fail out of a duct
54 I
--and drop into the bearings, which will disrupt normal operation, cause additional
56 I
1 ?
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0
2
-
friction, and eaay failure.
Tn ths_procese_of_inacbining_and_in_ storing the_f_ralass_prior_to "b1y, th
4_1
_Ashould be kept in special packings to prolect them from scratches and dust.
? 6
6. Assembly of the Bearing Unit
10--
12-
14:1
16_i
18_
20_
22_
24.-
26
The ball bearings of gyroscopic inst
they are subject to vibration and impacts
speed (up to 23,500 rpm); the temperature
sons, the bearings must meet rigid requir
sions, surface finish, hardness, minimum
guaranteed period, resistance to corrosio
speeds.
Two types of bearings are distinguished in gyroscopic instruments.
Bearings which provide for free rotation of the rotor relative to the principal
? ents operate under difficult conditions;
the rotor rotates at a high rotational
varies from +50 to -60?C. For these rest,
ments as to accuracy of geometric dimenr.
;riction, failure-free operation over a
1, and smooth running at high rotational
28
axis of the gyroscope are called principal supports, while those which provide for
?free rotation of the gimbal suspension are called suspension supports. The rotor
32_1
macs, resting on the principal supports, rotates at an angular velocity which is
34=1 1
many times greater than the rotational speed of the outer and inner frames of the
36
38-- ?
This constitutes the basic difference between@the principal supports and the
40_1
_J suspension supports.
42_j
1 In setting the bearings in the instrument, proper clearance must be maintained.
44:1 large clearance in the bearings leads to a shift in the center of gravity, which
46
:Icauses precession. A small clearance causes an increase in friction. The moment of
48-1 1
--friction in the principal bearings has an effect only on the power consumed in ro-
-Jtating the rotor, while the moments of friction in the suspension bearings of a gyro-
52? 1
--,scope cause precession of its axis.
54
-j
56
Let us examine the effect on the. stability of a gyroscope having a weight P and
STAT
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Declassified in Part - Sanitized Co .y Ap roved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
a horizontal axis, by a shift of its cent r of gravity along each axis of coordinate
A shirt of the center_of_gravity:_along_th rtical-axis-produces_no_noment.---Con---
versely, a shift of the center of gravity along the horizontal axis, perpendicular
to the principal axis of the gyroscope, generates a noment relative to the principal
8
axis - a moment which will be absorbed by the outer ring of the gyroscope. In dis-
10-4
placing the center of gravity along the p5incipal axis of the gyroscope, directed
12
horizontally, a noment equal to ?Pc and eIrresponding to the axial clearance tc in
the principal supports is produced; this causes a precession with an angular veloc-
ity of
20?)
22:
, Pc
w -r
? P2
(32.1)
From this we may conclude that an axial clearance in the suspension supports of
24--
-,a gyroscope with a horizontal axis of rotation, from this point of view, is imper-
261
-Jmissible. However, for proper assembly stich a clearance is necessary; therefore, i
28
=dshould be reduced to the minimum possibleisize, which is determined chiefly by the
30_
--correlation between the temperature coefficients of linear expansion of the rotor
32_-
body and axle. The principal supports of a gyroscope should have maximum accuracy,
34:1 36since the rotor rotates at high speed. When the shape of the principal bearings is
:]--distorted (skew, ellipticity, etc.), even an ideally balanced rotor will cause
38--
ic forces which may lead to failure of the instrument.
Thus the following requirements apply to the supports of a gyroscope:
42__
a) Principal supports:
44_
1) accuracy in execution;
2) minimum permissible axial clearance.
48?
b) Suspension supports:
50--
1) accuracy in execution;
52-
2) minimum friction.
54
Ball bearings used in gyroscopic instruments are divided into three types ac-
56
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
? . .
-J
2?
cording to their design:
1) Radial (builtin)_bearingsicUaLA. metal ieparator4
2) Magnetic (dismountable) bearing with a metal or a. textolite separator;
3) "Thrust" bearings without inner ring and separator (the tapered axle which
enters the bearing, or the ball which replaces this axles directly touch the
balls of the bearing itself).
14? Radial and magnetic ball bearings ar7 widely used in electric gyroscopic in-
struments since; despite the fact that they have the same bulk as "thrust" bearings,
161
0
_2they have a considerably larger inside dipmRter. This permits their use on hollow
18_1
- shafts of comparatively large diameter - axles or shafts accomodating current feeds.
Magnetic ball bearings may be taken apart-and washed before final assembly of
22_
__the instrument, and in the process of use; this is their advantage over radial ball
24-1
bearings. For the principal supports we use ball bearings with a textolite separa-
' 261
__Aor, which ensures best lubrication; this is very important under conditions of higl
28-d ? --speed rotation. For the gimbal supports, where it is important that. friction be
30-1
--kept to a minimum, bearings with a metal 4eparator are used.
32dThe technology for producing the individual parts of a "step" bearing (axles
34_1 --,and bearing cups) was examined above.
36_1
Balls for "thrust" ball bearings are obtained ready-made from the factories.
38-1
40
42_1
ShKh 6 steel (OST 3426) serves as the material for the bails.
The dimensions and out-of-round of the bails are checked on a vertical tele-
--scope caliper. The surface smoothness is checked expediently on a microinterfero-
44H
--meter. Pits, scratches, burrs, protuberances,
--cannot be allowed. ?
48:i
blowholes, and traces of corrosion
The bails should have no uneven tempering or burnt spots. The hardness of the
--balls should be within the limits of 61 - 65 Rt. The quality of the balls is largo-
52-1
- responsible for the service life. In storage, the balls should be lubricated
1
56_4
STAT
--with acid-free grease after Iveliminarywashing, and should be packed in boxes lined.
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0
?
with oiled paper.
ch_do_not_satisfy the spec ic_reviremorits_anci_which_haTe_an_Rnew-
ance are subjected to additional machinin honing on a lapping machine.
6
le ? ? h s . . ?
10--
The assembled bearing should provide smooth and even running, without jerks and
12-
-lstarts, for the rotor and the gimbal ring. The bearings should cause no vibration
14_
__of the gyro assembly and should not set up much noise in operation. The smooth run-
16--
__ning of the bearings is checked separately as well as in the gyro assembly. The
18_-
28
30
32
34
36
3
40
42
46_
48_
52?
Fig.360
sion supports of
0.3 - 0.5 gm-cm;
0.5 - 0.7 gm-cm;
bearing is calibrated with a standard gage in-
serteol in a special frame together with the ro-
tor. :In the bearings the rotor should rotate
1
smoothly and noiselessly. Poor quality of the
bearing balls is determined by a characteristic
sound caused by uneverarunning; when this is
discovered the balls must be replaced.
Minimum Friction
The moment of friction causes precession or
1
sets up a zone of stagnation. For the suspen-
1
pneumatic instruments, the moment of friction should not exceed
1
for the suspension supports of electric gyroscopic instruments,
and for principal supports, 0.6 - 0.9 gm-am.
of a "thrust" ball bearing there should be clearances
the balls of the bearing. In these bearings, the sum of
1
balls, when the 'latter are in contact with the raceway, is
For normal operation
along the raceway between
the intervals between-the
-icalled the total clearance.-
56
The total clearance may be determined from the geometric dimensions of the
S TAT
r
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
bearing. The schematic distribution of the bal.ls is shcran in Fig.360.
the_interrelation_of_the valueri?
41
6
8
10
12
14
16
18
20 Since
22
24
S, the total clearance between the balls in the bearing;
We Dust find
It, the radius of the bearing-cup rfceweiy;
r, the radius of a ball;
n, the number of balls.
From Fig.360 it follows that
then
? 26
a r r
sin ? = or a ;
2 R- r =2 arc sin R - r
(n - 1) cc =2 (n - 1) arc sin Rr- r.?
1 0
cp. 2T: -2 (n -1)arcsin
28 -r
30 or
32
34
36
3 Since
40
42*
44
46
then
r '
-1-.1c-(n-1)arc sin R -r.
2
( R r) sin --L= (R?r sin [1r -(n-1) arc sin r
2 2 R - r
=(R-- r) sin [(n - 1) arcsin
R - r
a= S+2r,
S= 2(R - r) sin [(n - 1) arc sin R r ri 2r
48 or
:? L_ S 2 f(R ? r) sin [(n - 1) arc sinR -2:-] .
- r
54 1?By-thi-s-forre1la..-1(e-may alio,- in selective assembly, determine the-dimenzions-of
--the-balls-f-or-&-given-radius -of the bearing-cup raceway-or,- on-the-other-hanirde;---1
(18.2)
1 STAT
?6-
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0
2
4
? ,
11.0.11,11,11.1?11.40W.M.
termine the radius of the raceway for a given dimension of the balls, when the val-
e
mes_of_S_arealso-givem
The amount of clearance is measured with a clearance gage.
The total clearance between the balls dernds upon the dimensions of the balls
?and the diameter of the bearing-cup raceway. When the dimension chain is computed
10--
we may find that full interchangeability cannot be Obtained in assembly. To provide
12?
_1
for the required clearances, selective asrmlAy should be used.
14
Before being set in the bearing, thitballs are strted4hito groups. he balls
16-1 in a single bearing should be of the sameLize, lith permissible deviations of
18_
0.002 aza.
20_
Asleeseardh has shown, the moment of friction in bearings increases during a
22
--period of 25 - 50 hrs after the instrument starts to operate. If, after this period
24--
-the bearing is taken apart and washed, the moment of friction returns to its origin-
2830
process a thin chip is removed; this fouls the bearing. For this reason, the bear-
32
al value and does not increase during the subsequent operation of the instrument.
This is explained by the fact that the bails run,-in to the raceway, during which
34
36
3
40
--Fig.361*,
42_1
?essary to
inga should be subjected to running-in before they are set in the instrument.
Checking the Moment of Friction in Bail Bearings
The moment of friction in "thrust" bearings is checked on the setup depicted in
by a method of checking the moment of displacement, i. e., the moment nee-
'
displace the lever which is set on the bearing.
The setup consists of a pedestal (1) on which the teaPing (2) which is being
?checked is set. In the bearing is set an axle (3), to which is attached a lever (4)
48:i
50:d
44_
On one end, the lever carries a cup (5) which is acted upon by a stream of air; on
the other end is a counterpoise (6), to maintain equilibrium. The stream of air is
52--
54
released from the mains by gradually opening the valve (7), until the pressure of
56 --141.-The---setup-wae-proposed-by -Eng A .Kondratyuk.
STAT
sgt.
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
28-- Fig.361 ? Schematic Drawing of the Setup for Checking the Moment of
30__ Friction in Thrust Bearinga. Constructed by Eng. S.A.Kondratyuk
32__
34__
40
42
44
46
.48
50
59
54
56
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
10
12
14
the air issuing from the nozzle (9) overc mes the moment of friction and makes the
er.441..rotate,At_that_noment,a_c ation_is_made_from_a_water_gagm (8), Welk
? II ?I
is calibrated directly in units of the moment of friction.
16-
18_
20......
22_
24--
' 26--
--ing balances the moment set up
28-J ,reversed by means of the lever
30_J
--both directions.
The moment of friction in built-in b
is checked on the setup depicted in
Fig.362. This method of checking has beelt adopted in ball-bearing factories and is
Icalled checking by the angle of deviation
The setup consists of an electric mol'or with :reduction gear, which rotates the
'
spindle (1) at a speed of 20 rpm. By meas of ca change-over mandrel, the bearing (2
is fitted tightly onto the spindle by meals of the internal ring. By means of the
spring-filled lathe dog (3), the pointer
A) With the weight (5) is fitted to the
outer ring of the ball bearing. The poin er moves across the scale (6) which is
divided into degrees. As the spindle is made totrotate, the .pointer and weight are
entrained by the outer ring of the bearing until the moment of friction in the bear-
32
by the weight. The rotation of the -spindle may be
(7), which 'permits checking the moment of friction in
If we know the magnitude of the weight G, the radius r at which it is placed,
34
and the angle of deviation a calculated from the pointer position on the scale, it
is easy to determine the moment of friction
36
3
40
42-
0
44_1Lubrication of the Bearings
46_4
Mfr=Gr sLx.
(18.3)
When the rotor bearings are insufficiently lubricated, its operating surfaces
481
rapidly, and when operating in a humid medium, corrosion takes place. When the
50
lubrication is excessive, the number of revolutions of the urokheel is reduced
-"whenever the instrument operates at low temperatures (freezing weather), due to a
54
5
56-sharp rise in the viscosity of the oil (the lubricant thickens ani increases the
STAT
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0
2
oial_types otioil_areused_for_lubricating_the_bearingspertiftc_grav=
ity of the oil is 0.868 - 0.875. The poux! point is -57?C. When t = 50?C, the via-
4
8
10
12
The felt stuffing boxes, installed into the bearings are soaked to saturation
14:]__with oil.
16?
18_ As research has shown, lubrication ol ball bearings in the supports of the gim-
bal suspension increases the friction, especially at low temperatures. For this
20_
reason, the use of lubricants for the supports of the gimbals is justified only by
22_
the necessity of protecting the supports from corrosion.
24--
A ball bearing installed in an instrument should be demagnetized, since magnet-
26_ic forces will increase the friction.
26dBall bearings which have been lubricated with oil should be kept in closed jars.
30_
Before assembly, all parts of the bearing are washed in gasoline and re-lubricated.
32_
The service life of the bearings of gyroscopic instruments is about
34_
_320 - 350 hrs.
36__
?
cosily is equal to 1.5 Ehgler.
The oil should be clean and transparint. Two or three drops of oil from&
snail eye-dropper are put on each bearing.
32-7. Assembly of the Gyroscope Unit
40__
Let us discuss the assembly of the gyroscope unit, using the assembly of a gyro
42
__horizon as example (Fig.363).
44_
The process of assembly starts with assembling the housing of the rotor (1)
46_
with plugs which close off the apertures in the external wall, apertures which are
481 --necessary for the nozzle cut-outs.
50?
The plugs are set into nitrocellulose adhesive; the adhesive must be prevented
52--
--from flowing into the nozzle apertures. A check is made by measuring the air con-
54
-1sumption; the amount of air, according to technical specifications, is between 49 and
56
--1
STAT
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?
0
? 55 ltrimin on the unit when there is a prtssure variation of 90 mm Hg. In checking,
2?
he_housing is clamped endwise_to_a_rubber &asket.__The_p1ngs_ars-Isa3ie&-on--th,e--?ut--
.
4-
6
8-
22_
24-
-
? 26-
28-
30-
32_
34___
36_
3
5 1! 11 17 7 )7 A9
40 Fig.363 - Overall View of a Gyro Horizon
42 1 - Rotor housing; 2 - Cover; 3,4 - Axles; 5 - Rotor; 6 - Step bearing;
44 7 - Balancing screw; 8 - Cover; 9 - Spring washer; 10 - Bearing cup;
46 U - Gaskets; 12 - Telt washer; 13 !- Housing of stabilizer; 14 - Shut-
48 ters; 15 - Shutter axles; 16 - Gaskets; 17 - Weight; 18 - Frame;
1
50 19 - Axle; 20 - Bearing cup; 21 - Axle screw; 22- Scale; 23 - 0askets;
5 24 - Frame Plug
54 ' ----1
1
56
side and cleaned underneath, together with the rotor housing. The next step is lap-,
i
STAT
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o?ml.??????.......?????????IPI.????????
^
0
2 ping the lower end of the housing on a special cast-Iron, rotating disk, and lapping
_the_upper_end_on_a-cast-iron_plate.__Aftel_this,the_hon wning_unit_is_washed_in-gaso
4:d
line and dried.
6
8:J
Assembling the rotor housing (1) will the cover (2) is done by the selective
Inethod. The cover should go into the housing without agy play, and should closely
10--
adjoin the ends. If a clear gap is detected between the ends, additional lapping is
12_ 1
necessary.. Once they are selected, the Tor housing and the cover are narked, the
screws are backed off, and filed from the out-
side in. The air consumption is checked under
the sr conditions as in the preceding opera-
tion., Press fitting of the axle (3) of the ro-
tor housing is done on a special device. Before
26 press fitting, the aperture and the air duet
-.--
mist be carefully cleaned and blown out with come-
pressed air. The strength of the shrink fit is
checked on a special device by applying a torque
18__
20--
22::
24--
28-
34_
Fig.364 - Device for Checking
of 25 kg-cm; the mall should not revolve under
the Strength of the Shrink Fit
this force.
36 of the Rotor Mae Housing
The device for checking the strength of
3
--press fitting (Fig.364) consists of two levers (1) and (2),hinge-joined.by means of
40_
?a spring (3). The collar (4) of the device has an aperture bywhidh it is centered
42__
--along the axle. The collar contains joint pins (5) which drop into theaperturesof
44_
the axle for passage of air; by these the device is connected with the axle. The
46?
--long lever (2) sits freely on the collar, while the short lever (1) is rigidly con
50 ?nected with the collar. In. checking, the long lever pivots to the support (6); it
--
--stretches the spring (3) and through the short lever sets up the necessary torque
on the collar.
54-
56
The accuracy of the press fit is checked with an indicator gage, by turning the
STAT I
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--rotor housing on the base of the cone of he axle and the opposite aperture under
2--
the_bexciTIg. The_ indicator_ gage, placed_ along the di asnetter_e_the_axlel?shoulsi_not-
4_1 show a deviation of more than 0.015 mm. If this is not the case, straightening is
6
required, with a subsequent check of the torque. The air consumption is checked un-
8
__flier the same conditions as in the preceding operations.
10--
Shrink fitting the axle (4) to the rotor (5) (Fig.363) is done on a hand press;
then the rotor is rolled on all sides in Trder to eliminate any eccentricity which
14_1
__might occur in the process of press fitting. The operation is done in the back cenr.
16
_4ters which are generously lubricated with grease. After the rotor has been machinedr
181
__the cones are checked through a magnifying glass which enlarges thirty times; after
_this we proceed to balancing of the rotor
22_
24 Balancingthe Rotor
26___
In the production of the rotor, some eccentricity relative to the axis of ro-
28?
__tation is unavoidable; in assembling the rotor with the axle, this eccentricity may
3??increase still more, as a result of the eccentricity of the axle. itself.
32_1
34:1 nanic reactions in the bearings and leads to early failure of the latter.
36
Apart from eccentricity, nonuniformity of the material also causes unbalance of
3
the rotor.
When the rotational speed is high, an unbalanced rotor causes considerable dy-
40_
When the rotor rotates, unbalance will cause vibration. Apart from improper
42___
--balance of the rotor itself, vibration may result from axial and radial wobble of
44_1 --the bearings, gaps, different diameters of the bails, a skew in the bearing cups,
--inaccuracy and roughness of the working surfaces, and the like. Axial wobble of the
48-1 --supports causes a reciprocating motion of the rotor along its axis; this sets up dy-
50-1
--namic reactions in an axial direction.
52--
Radial wobble causes dynamic reactions, just as a statically unbalanced rotor
54
? --does. Radial gaps lead to a shift in the center of gravity.
.4
-103
STAT
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2:1 Different dimensions of the balls and inaccuracy of the working surfaces (out-
ofet_t- rue gra/1117 At% raceways of_the_bearinglonpaLanri gain formation_on_the_working___
surfaces of the rotor axle) lead to a shilt of the geometric axis of the rotor and
6
cause dynamic reactions. Dynamic reactions may also result from a deformation in
8.-_
the rotor axle, a defect in the power supply for the gyroscope unit, a change in t
10-4
_J
perature conditions, and wear of the supports during operation.
12
14
Thegreatest dynamic reactions caus4 by improper balance of the rotor vary, in
the selected radial direction, in accordance with a harmonic law. This basic dynam-
16--
_ic reaction is superposed by oscillations' differing in amplitude,and
frequency, a
18
20_
phase, which produced by the numerous calls mentioned above.
Balancing is divided into static balancing and dynamic balancing. Static bal-
22_ 1
? ancing is present when the rotor is not rotating; its aim is to bring the rotor into
24_ I
r
indifferent equilibrium, relative to its axis of rotation. Static balancing is pre-
26_ 1
I
_sent in devices with bearings into which the rotor is set. The bearings may be ball
28_ I
?bearings (the same kind as in the instrument) or knife bearings, which are used for
' 30_
1
?a rotor with a pressed-steel axle.
32_ 1
To determine unbalance in static balance, the rotor is inserted in the bearings
34_ 1
?of the device, and the working clearances of these bearings are checked. An unbal-
36_1 1 ?
?anced rotor will tip downward with that part of the rim on which there is an excess
38--
40 of material. For correction, a small plasticine ball is pressed on the upper part
_ 1
?of the rim. The size of the ball is selected from calculations intended to bring
42
1
--the rotor into a state of indifferent equilibrium.
44_
46_ After this, a hole is drilled into the rim of the gyrowheel in a spot opposite
--the place where the ball was added. The hole is so calculated that the reduction in
48_1 --(the moment of force due to the weight of the removed material corresponds to the mo-
50_1 1
--ment set up by the weight of the plasticine ball. Then, after the ball has been re-
. 52--
--moved, the rotor is again placed into the device, and the balancing is checked; if
54
56--there is insufficient equilibrium, the balanf.ing is rechecked. It is important to
58
STAT
31.9
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Olt
0
have as few holes as possible on the rim cf the rotor, since they increase the air
2
loruon_the_rotor.
4
6
8-
10-
12
14
__ment of unbalance Munb< 0.3 gm-cm. Let 1us determine what eccentricity e the no-
16
ment of uhbalance ITEL1 correspond to if the weight of the gyraaheel is pi= 500 gm,
_
18
20
Alw= (74? w4whce e (3'3 0 0006 an. ; (18.4)
22 G =500=
24 Nhen the rotor is rotating at a speed of 15,000 rpm, a dynamic load P will re-
, 26 main on the bearings of the rotor. This load may be determined by the following
25 formula:
Static balancing cannot fully eliminate unbalance of the rotor due to the mo-
ment of friction Iffr in the bearings of the device, because of this, it is impossi-
to define the moment developed by unbalance of the rotor Munb < Mfr.
Let us assume that the moment of friction Mfr'in the bearings in which the ro-
tor was balp_nced is equal to 0.3 gm-cm.
s does not alloa determination of the
? 30
32
34 For our example we will obtain
36
P:4?Q2e.
_ ________ _ J
- - --
500
P.?? 1570' ? 0,006= 753 gm ?
3 *-981 --- -
I
40 In addition, by means of static balancing, we can balance the rotor relative to
42_ ts axle only in such away that the centers of gravity of the two halves of the ro-
1
44_ or will generate the sane moment with respect to the axis of rotation, but will be
46 ocated in different cross sections of theirotor. In this case, during the rotation
48_ moment is generated in the plane of the axis of rotation, and this too will cause
18.5)
U.
50-1
5
ynamic reactions in the bearings.
Dynamic balancing, real-Ned while the rotor is rotating, permits us to balance
54-- t-dynamicallIc--In-additiono-as a more sensitive-method-i-dynamic balancing-allows
56- spotting-of--unbalance-whi-ch --cannot- be detected - in-static-balancing-because -of-th
I
STAT
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
0
presence of a moment of friction in the b arings.
2-1 Statio_balancing_is_done 'before
4ding and eliminating coarse inequilibrium.
6
10 ?
12?
_
14_
16 ?
18_
20_
92__
24 --
. 26:d
28?
? 30_-
32_
34_
36
c._bp1 pncl ng_and-is-necessary_for_detect,
Dynamic balancing maybe done on ham devices or in special setups.
Secii.on AB
_
Fig.365 - Devil for Balancing
The device for balancing (Fig.365) consists of a frame (1) whose apertures con-
tain two rods (2) on a single axis. The rods maybe moved in an axial direction;
3 this is necessary for setting the rotor and for regulating the clearance between the
rotor axle and the bearings (3). After regulating, the rods are fixed by means of
40:i the lathe dog (4) and the screw (5). The rod has knockout die (6) for removing the
42_1
?bearing when it is to be exchanged. When in operation, the device is placed in the
44_1 hands of the operator. The rotor in the device is made to rotate by an air jet or
46=1 ?by mechanical means.
43_
At first the rotor picks up a slight speed; this is then increased to the speed
50--
--required by the technical conditions. If, at law speeds, the device begins to vi-
52--
--brate violently in the hands of the operator, the rotor is stopped, since a further
54
--increase in speed may lead to destruction of the bearings. After the rotor is start-
STAT
?1.06
:Pi ?
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ed, the operator, holding the device in hand, will feel the vibration. Then the
2
_motor_is_stopped_and a_plasticine ball_is_pressed_on_the (via of_the yhPA, rim where
4_,
__the greatest vibration occurs.
6
10-
12
14_
16-
18_
20
22
24
- 26
28
30
?
If, on re-starting the rotor, the vi ration increases, the ball is moved along
the rim until a place is found where the ball will produce the least vibration. At
the same time the size of the ball is selected, i. e., the quantity of plasticine
which will produce the least vibration. 1 nen the desired results are obtained on r
one end of the rim, the entire process is repeated in the same sequence on the other
end of the rim. If, in balancing, an increase in vibration of the device at the op-
posite end of the rotor is observed, plaJicine balls must be placed on both ends.
When the vibrations are no longer felt,
the rotor is removed from the device.
Then, on the opposite end, in a direction
/0 11 diametrically opposite to the ball, a
hole is drilled, just as in static balanc
ing. Finally the rotor is checked at a
speed somewhat exceeding the operating
speed. .
Such balancing of the rotor is based
32 Fig.366 - Special Device for Pro-
34__ tecting the Bearings from. Falling
36 Chip in Drilling
3
1on the subjective evaluation by .the operator and depends to a large extent upon his
40_
-Jexperience and his ability to detect insignificant vibrations. In addition, the pr
42:d 1
1cedure is laborious, since the balls are pasted on by guesswork at first, the place
44_ i
Rselected for attaching the ball can be defined as "incorrect" only after the rotor
46 ,
--has been started. .
48_
50
If their axles are elliptical or if they have unevenly milled holes, some ro-
52---
--tors do not, in general, yield to balancing. For this reason the axles of a rotors
,
54 ?as well as the rotor itself, rust satisfy stiff requirements as to accuracy in their
56 --execution.
-147-
S TAT
311"
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In balancing a rotor, smoothness of he bearings is highly important. After
_.......several_rotors_have_been_balanced, the b ings_are..washed_ and-lubricated-with oil.-
4:1
The axle cones are rubbed with cottonwasle, then with tissue paper. Clamping the
6
axles when regulating the clearance is no allowed. After balancing, the cones of
8
the rotor axle are examined and polished.
To eliminate the possibility of chip dropping into the bearing, a special do-
vice is used with the drilling machine; i consists of a fixture, an oil filter, and
a vacuum pump. A diagram of such an sr,-
rangement is shown in Fig.366.
K The end of the spindle of the drill-
ing machine is mounted to hollow casing (1
of the fixture, in which the movable ea-
22_
24--
- 26--
28?
Fig.367 - Special Setup for
30_ Static and Dynamic Balancing
32_
;
1
. lar (2) slides. The drill (3), attached
to the spindle of the machine, passes
through the inside of the collar. The
spring (4) forces the collar against the
--rotor, thus reducing the excess clearance. Through the socket (5), a hose is con-
34? 1
nected to the hollow cylinder; the other end is connected with the receiving stud (6
36=1 I
--of the oil filter (10). The air, passing 'throughthe chamber (8) with its oil and
3 i
40 strainers (9), is cleaned of chips and dust. The vacuum pump (11) is connected to
--the outlet tube (7) of the oil filter. The vacuum pump is started simnitaneously
42_1 1
with the machine, and all the chip and metal dust is sucked from under the drill in-.
44_ 1
-1
1to the oil filter. For static and dynamic balancing, a special setup is used; a di-
46._.
--agram
48 of it is shown in Fig.367. The setup consists of a frame (1) which is able to
-1
--rotate on a pivot about the axis 0X.
50-1
In the vertical position, i. e., in a position of equilibrium, the frame is
52--
54?fixed by two springs (2). The lower end of the frame is connected with a mirror (5)
56?through a lever (3) and a rod (4). Turning of the frame about the axis OX causes
-108-
STAT
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the mirror to turn. When an unbalanced. rotor rotates, it will set up a moment about
2
he aids OX, a moment_which_will_change_in_vallte ansi direction with-a_period_equal--
? to the period of rotation of the rotor. it the same time it will cause swinging of
4
6 i
the frame, and consequently of the mirror A ray of light incident on the mirror
8
from the lamp (6) will be reflected from i
.1t and, in the form of a pinpoint of light,
10--
? 16 ?
18_
20_
' 22_
24-
26......
28
30
32
34_ Fig.368 - Diagram. of the Setup for
36 Balancing the Gyroscope Rotors by
3
40
the Method of Acad. A.N.Krylov
will fall on the frosted-glass scale (7).
When the mirror oscillAtes, the light spot
will change into a line. For high sensi-
tivity of the setup, the period of oscil-
illations of the swing system should coin-
cide with the period of rotation of the
rotor, so that the phenomenon of resonance
.occurs.
To determine the dynamic unbalance,
the rotor is fastened in the frame in the
position (a) since, in this position, the
moment of the forces of imbalance acts on
Ithe springs alternately in both directions
To determine the static unbalance,
'the rotor is attached in the frame in the
position (b); in this position, the dynamic unbalance will not be noticeable. The
42 --balPncing principle is the -same as in the Iposition (a). It is impossible to define
44-1--Ithe spots which have an excess or a deficiency of mass on this setup. The device is
46_1
u? seful only for determining the amount of unbalance from the length of the diffuse
48
track of the light spot. At present, balancing machines are used which permit not
?only a determination of the amount of equilibrium, but also the spots which have an
52?
excess or a deficiency of mass.
54_1
56-1
58d
STAT
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Setup for Balancin,c a Rotor b the DirecttMeasurin Method
This method of balancing rotors was first reported by Academician A.N.Krylov in
The setup for balancing the rotor is shown schematically in Fig.368. The end
ioJ face of the rotor (1) is marked with two black dots (2) staggered at a 900 angle.
12_ Oscillations due to reactions in the supports are transmitted through the flexible
14_ system to the pickups (3). In the pickup, whose principle of action is based on
16_ the excitation of an electromotive force in the turns of the coil, an emf is induced
18_when the permanent magnet in this coil is shifted. The frequency of this emf is
20= equal to the oscillation frequency of the supports, and its amplitude is proportion
22_a1 to the amount of the reactions.
24_ Across the integrating circuit (4) and the amplifier (5), the emf induced in
26? the pickup is fed to the vertical scanning disks (6) of the oscillograph tube (6a).
28 To determine the oscillations of the supports from the time or from the angular po-
_, 1
30._.sition of the rotor cat, voltage from the Ipecial generator (8) is supplied to the
32 ?lhorizontal scanning disks (7) of the oscillograph tube. On the screen of the ?soil-
;
34 lograph tube we will obtain a sinusoidal curve whose amplitude will characterize the
361 amount of unbalance. The sinusoid is obtained on filtering the component oscilla,-
3
tions of higher harmonics.
40_ The position of the unbalance is determined in the following manner: A ray of
42_11ght, reflected from the end face of the rotor with its black marks (2), is direct
44 onto the photoelectric ell (9). The light oscillations, transformed into electric
46-1signals, pass through the electronic amplifier (10) onto the screen (11) of the os-
48_
cillosgaph tube.
50:: These signals will stop the flow of electrons (a) at? the instant when one of
? 52--the black mark enters the field of the photocell.
541 Ln-this-.way-,-for-ono turn of the rotor, the screen of the osciilograph-will,---1
5 6have_a_sinusoida.1--curve-with two
_1151 STAT
Tows,.
137
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0
10
16-d
The housing of the step bearing (6) (Fig.363) should move in the aperture with-
out friction produced by the spring washer. The fit of the step-bearing housing in
the rotor case corresponds, according to the blueprint, to a sliding fit of Class 2
__accuracy. The aperture has a tolerance of +0.023 mm; the shaft has a tolerance of
-0.014 mm. The maximum clearance possible is 0.037 mm, but according to technical
specifications it is limited to wlthin 0.02 mm. The 0.02 ma clearance ray-be ob-
tained in two ways.
When the first method is used, the manufacturing accuracy is considerably in,
The position of the gaps on the curv4 characterizes the distribution of the
on. the rotor_and the_direction of_the_unbalance.
The ordinates yl and y2 will coincide with the components of unbalance along di
aneters drawn through the marks on the ends of the rotor.
The direct measuring method 4.3 thelmost nearly perfect and the most progressive
Qt,
method, in comparison with all others.
6
Assembling the Rotor Case and the Step-Bearing Hous
181
20_
22_
24
. 26_
98--
30-
32_
creased as a result of the fact that the class of accuracy of the fit is raised; haw-
34
ever, this makes production considerably more expensive and requires more accurate
36:1 _,equipment. With a method such as this, machining the parts becomes uneconomical and
38-1
?even unfeasible with tha equipment we now have.
40_
The second method retains the greater tolerance as economically acceptable for
42_
production, but in this case selective assembly must be used. Selective assembly
44
y be done by direct selection or by preliminary sorting of the parts into groups.
46
In subsequent operations, the balancing screw (7) is screwed into the rotor
48? 1
case with shellac and
fitted and the spring
? 52?
is safetied with the nut (8); then the guide pin is shrink,-
gasket (9), lubricated with oil, is inserted (Fig,363).
? Checking the quality of the assembly is done by exerting finger pressure on the
54_
?
?housing of the step bearing; under the effect of the spring, the housing Should move56
-21.1 STAT
?S'..tc%
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Declassified in Part- Sanitized Cop Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
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-without rubbing.
2?
? 4: IttEle Bearings
6
8
The bearing is taken apart and washa-.?Then a check is made to see if the be
ing cup (10) (Fig.363) goes into the aperture.
10-1 .
Igo into the aperture to 2. of its length. If the above conditions are observed
121] 3 4
and the cup does not fit into the apertur, , it is reamed to the necessary size. Aft-
14:1 er this, the gasket impregnated. with EVP oil is put it its socket. Press-fitting
16-4
the cup may be done by hand, with light bloas by swatch hammers or else on a press.
Under hand pressure, the cup should
18_
After this, the press fit of the cup is checked for end wobble. Permissible
wobble is 0.015 mm. After scavenging the cup with dry filtered air, we proceed to
22_
_assembling and lubricating the bearing. o keep the bearing from becoming fouled in
24_
__the process of assembly, tissue paper Is placed under the washer of the bearing.
26-
Press-fitting of all the other bearings is done by the same method. In press
28--
__fitting the upper bearing, it is impermissible to increase the diameter of the haus-
30
ding of the step bearing. This housing should move freely; the permissible clearance
32
is not more than 0.02m.
34
36 Final Assembly of the 0yro Unit
3
The gaskets (Fig.363) and the elastic washer (9) are placed into the cover (2)
40
41.
of the housing. Then the felt washers (12), impregnated with oil, are set in the
42__ 1
--housing of the step bearing (6); after this, the step bearing is set in the cover of
44__It 1
-- he housing. A gasket, lubricated with oil, is also put on each bearing. After
46_1 1
__this, the rotor (5) with its axle (4) is inserted in the housing (1). The axial
48-d 1
__clearance is regulated by the gaskets (il), and is set within the limits of 0.04 -
50-1 1
--0.07 mm. The amount of clearance is stipulated, on the one band, by the requirement
52--
-
54 i
_-_of keeping the shift in center of gravity to a minimum and on the other hand by the
56
-41ecessity of assuring normal operation of the instrument at subzero temperatures.
STAT
34-1
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2
IThe amount of axial clearance is checked
n a special device vrith an indicator gage.
dhematic sketch_of_the_device_i3_given4n_Fig.369.___The_rotor (1) is liftedlv___
4
means of the counterpoise (2) which acts In the rotor over the lever (3). The coun-
6 t
....iterpoise is lowered and raised, so that the axial clearance can be determined from
8
10-
12-.
14__
16--
18__
20__
22_-
24--
- 26--
28--
30__
32
34
36
i 3
Fig.369c- Device for Checking Axial Clearance
observation of the pointer. After the axmal clearance agrees with the technical
specifications for the unit, the following points are checked:
a.. Air consumption, which should be within the limits of 46 - 54 ltr/min it a
pressure of 90 mm Hg.
2. Operation of the rotor when the jet is small. Instead of the usual (Tres=
sure of 80 - 90 mm Hg, we establish a (pressure of 10 mm Hg and check the wear of the
40
--rotor at each hole. By this method, the bearing and the quality of balancing are
44_-
46_4
48:
50?
_
52-
regulated.
3. Smoothness of rotation of the rotor. The rotor is run for 4 ? 5 min; at a
pressure of 80 mm Hg it should run smoothly, without impact or vibrations.
4. The rotor run-out, regulated by checking the rotor travel at inertia. The
rotor is run for 5 min at a pressure of 70 mmHg. Technical conditions have estab-
--lished the inertia run?out of a rotor at a temperature of 18 ? 20oC as lasting not
54
56
less than 8 min and not more than 22 min. An upper limit is set because a high run-
STAT
4
4,5-41
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0
--iout means a large clearance. The normal inertia travel of a rotor at subzero tern-
2--
After inspection, the rotor is disaslembled, and the working parts of the bear-
6_,
_!ings are examined under a magnifying glass. A slight rolling of the balls along the
8--
--raceways is allowed. In checking the rotor, it is measured with a standard caliper.
10--
_A rotor 'which meets all requirements is r -assembled and is checked a second time in
12?
___Jthe same sequence (on the first four poin s).
14_
16_. Measuringthe Rotational Speed of the Rotor
18--
The rotational speed of the rotor can be measured with a stroboscope (Fig.370).
20_
_The stroboscope is a disk (3) which revolves rapidly at constant speed, its rotation
22_
al speed can be measured with a tachometer (4). A mark (2), in the form of a spiral
24
? 26
n rpm
28
30
32
34
isir rpm
36
Fig.370 - Stroboscope
3
40 is made on the rotor (1). If the rotor rotates evenly at n revolutions per minute,
42 then while observing the rotor through the slots in the rotating disk, the rotation-
speed of the disk can be so regulated that the mark on the rotor will seem sta,
4611itionary. Evidently, this will be the case only if the rpm of the rotor is equal to
A ?1
-5--or a multiple of the frequency of its appearance in the slots in the stroboscope
50 disk.
52--
If the number of slots is P, we will
have the relation
54
n=kNP,
(18.6)
56-1
cnA
STAT
1
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--where N is the rpm of the stroboscope disi;
2?
Ras any_whole_number_indicating_houll_revolutions_the_rotor-has-com---
__ pleted in the time between two consecutive appearances in the slots of the
6 _
8
10
12
14
the rotor again seem stationary under observation through the slots. This will oc-
stroboscope disk.-
It is clear that, by merely calculating N, it is impossible to determine the
number of revolutions n of the rotor, since the value of k is unknown. For this rea-
son, the rotational speed of the disk is increased or diminish?d until the marks on
16
cur when the number k is decreased or increased by one unit. After defining, from
18
20
22
24
26
28
' 30
32_1
34_
36_
the tachometer pointer, the corresponding
obtain
Excluding k from.these
ence
rotational speed Ni of the disk we wifl
n(k-1)NiP.
two equations, we will obtain
_ ,
n n
= g-
N
PNNI
n= N -N?
(18.7)
(18.8)
38--8. Assembly of the Damping Unit
40-d
The faces of the stabilizer housing (13) (Fig.363) on which the flaps (14) will
42
- e installed should be lapped for greater surface smoothness and evenness. To ob-
44_1
__tain a good hermetic seal, the upper end of the housing is also lapped. The flaps
46.1
_Jare weighed and paired; according to technical specifications the difference in
?weight in one pair should not exceed 20 mg,. Different weights lead to the displace-
50_I
- ent c2 the center of gravity of the pair of flaps, making it impossible to install
--the flaps gy-metricall7 along the openings.. Assembling the flap axles (15) with the
- ousing is done by the fitting method, since it is important that a small radial
56
? 5
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clearance of 0.05 to 0.03 = is left, Tcfai+ is difficult to obtain by the full inter-
2
chnngety_methoda__The aperture_irLI.Wdamper_bousing_is_reawd-until the_moper-
4:j surface smoothness and the required clearice are obtained. The clearance is checked
6 I.
Iby setting the axis of a flap in the apertAire. Assembling the flaps with their axis
8--
is done in the following manner: The flay) is shrink-fitted on one end of the axle.
10--
In doing this, bending of the axle must be avoid-
12
ed. The end of the axle should protrude 1 - 2=
14
16 from thr flap. Then the gasket (16), 0.13 ma in
thickners, is put on; after this, the axle is in-
troduced into the aperture in the housing. On the
other side the same kind of gasket is put ?nand
the second shutter is shrinki4itted. Plates of
0.13 =thickness are placed under the ends of th
flaps. !The flaps are levelled and the required
axial clearance (0.01. - 0.025 ma0 is established.
18
20
92
24
26
28
30 _
32
Fig.371
?
Th p clearance between the flap and the hous-
ing should be preserved along the entire length
34
f the flap, no matter what position the damper is in. Then the overlap of the flap
36
ver the openings is checked. When the damper housing is suspended in a horizontal
3
-- lane, the flaps should half overlap the openings. After the flaps are installed,
40
hey are soldered to the axle. The strength of the soldering is checked for torque
42_1
?which, according to the technical specifications, should be not less than 1 kg-am.
--After final assembly of the unit, the overlap of the openings, the radial and axial
46__
--alearances, and the clearances and friction in the flap supports are all checked ac-
48_1
ording to the technical specifications.
50
Accuracy in the vertical installation of the flap determines the accuracy of the
strument operation. Friction in a flap axis of rotation causes an angle of stag-
56 t As is seen in Fig.371, the flap misses reaching the vertical by an angle
?
5
54
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-1j6- STAT
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_at which the moment of the force of gravity Pt sin a balances the moment of fric-
8,
1 0
16
18
20_
22_
P1 sin a= Pr or sin a a :.--- I (18.9)
(Since the angle is smAll, we treat sin a as equal to a). Consequently, the angle
of stagnation due to friction in the flap axle will be expressed as
--1
? (18.10)
where I.' is the coefficient of friction in the axis of rotation of the flap;
r is the radius of the aperture in the flap;
I is the distance between the centell of gravity and the axis of rotation of
the flap.
24_
The dimensions r and / are indicated by the designer so that the technologist
26_
can reduce the angle of stagnation of the flap, chiefly by decreasing the coefficien
28
of friction. ?, which depends on the smoothness of machining of the friction surfaces
' 30
To reduce the force of friction F in assembly, the necessary clearance should be es-
32_
?tablithed not only in the radial direction but also in the axial direction. In ad-
34_
_dition, we must see to it that the aperture and the mac: of the flaps are correct in
36
form, so that there is contact along the largest possible surface area. If, in as-
3
seMbly, the axle of the flaps is bent, incorrect positioning of the axle in the bear
40
-Jing and rubbing at various points will result.
42_
44_9. AsseMb4 of Gyroscopic Instruments
?
4d
Let us examine the general problem of assembly, as before, with the assembly of
48=1 --a single gyroscopic instrument, namely the gyro horizon (Fig.363), as typical
--example.
1
52--
1
54
. 50_-
56
-u7-
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--r.neinPt1BaleiDr
4__ Balancing a gyro unit is done to indifferent equilibrium within the limits of
6the_angle_of_suing_of_2the_pmdullmatlaps._ The balancing_is_done_in_two_ste n (thn
L,
10-
12-
14__.
22
24
? 26
28
30
32
34
36
3
first in the vertical plane and the second in the horizontal).
L_ _
Fig.372 - Device for Balancing the Gyro Unit in the
Vertical Plane
40 By balancing in the vertical plane, the center of gravity of the unit is shift-
1
42_ edto the vertical plane which passes thr9ugh the axis of rotation of the rotor cas-
-11
44-iing. This operation is done on a special. device (Fig.372) in which the gyro unit is
40placed in the bearing. The bearing (1) ij connected with the axle of the rotor cas-
i
48:ding, and the bearing of this casing is connected with the axle (2). Rotation in the
50:ibearings should be regulated to compensate axial novement of the rod (3), so as to
1
52=Jjensure free rotation of the gyro unit without noticeable radial play. After this
c,-1
-pgiEUMA'aigi7the-rod-is fastened by means of the nut (4). The regulating-screws-0)-
56-Icheck-the-device-so-that-the axis of rotation of the gyro unit--is horizontal.
STAT
_118.
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To obtain the necessary balance, email pieces of lead are cut off the balancing
eights...which are fastened_on_both_sides_of_the-rotor_casing41)
? 4d
gyroscope assembly is brought to a position at Which the pendulum flaps (14) half
6
overlap the slots in the damper housing (13).
8--
Balancing in the horizontal plane is done after the gyro unit has been balanced
10--
_in the vertical plane, 1. e., when the center of gravity is already located in the
12-
14_
16?
_
18_
20_
22_
24?
vertical plane which passes through the axis of rotation of the rotor casing, but
may still be located above or below this axis. This balancing must make the center
1
of gravity coincide with the axis of rotation of the rotor casing. The gyro unit
should be located in an indifferent position within the limits of the angle of swing
of the pendulum flaps. The operation is done on the same device, by moving the
1
weight (17) (fig.363) along the balancing screw (7) until the gyro unit, within the
1
limits of the angle of swing of the pendulum flaps, will remain in any of the preset
26
dpositions.
28?
? 30-
32_,
In the process of balancing, the gyroscope asseMbly may occupy various
positions.
1. The gyroscope assembly remains in the extreme position of inclination when
__it is tilted to one side, and returns from such inclination, moving to a horizontal
36_1
_-position, when it is tilted to the opposite side.
38-1 Reason: One weight, attached on one side, is heavier than the opposite one.
40
As a remedy, this part of the weight is cut off.
42 1
2. The gyroscope assembly remains in the extreme positions of inclination and
. 44
_flaDves to these positions when the angles if deviation from the vertical are small.
46?
Reason: The center of gravity is located above the axis of rotation; the balp.
48--
--ancing washers - the weight (17) (Fig.363) - are too high. The weight must be low-
50H 1
?ered or, if this is not enough, the number of washers must be reduced.
? 52--
54-
-or near-vertical position.
.56
3. The gyroscope
asseMbly leaves the inclined position
and occupies a vertical
581
9
STAT
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Reason: The center of gravity is .lo ated *below the axis of rotation. The bal-
2
__Encing_mehers_(17)_must_be_ra.isecLor_tho r Timber increased-
The balancing is considered complete as soon as the gyroscope aggregate remains
6
in any preset position, within the limits of the angle of swing of the pendulum
8
_ flaps.
10?
_ After the weight is balanced, the ac
12--
18._
20_
22_
. 26_
28--
30_-
32_
34__
38--
coated with black spirit varnish.
Assembling the Frame with the Parts
40_
42_
44
46_
ew heads and the balancing washers are
i
The axle (19) and the bearing cup (2?) are press-fitted in the frame (la), and
the weights are screwed in. The conditio s for shrink-fitting are the same as in
,
Fig.373 - Device for Balancing the Gimbal Unit in the
Vertical Plane
48?
-
501--the preceding units. After the frame has been assembled with all parts, it is bal.,-
-1
527:lanced on the device shown in Fig.373. In design, this device is analogous to the
54?idevice-depicted-in-Fig.372,- except -that it is somewhat larger in size and has-a--duct
4-1
----in-the-rod-for-supplying- air in process of regulating.---(A description of -the
58
_120. STAT
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lregulating process is given below.) The ocess of balancing the frame consists in
2
_bringing_it_to_a_atateof _indifferent_eq
?41
6
YEAS.
10-
-
12-
14_
16-
18_
20_
22_
24.-
. 26_
28-
_
30_
32_
34___
tion; this is done by cutting down the b
nt tn fhe Alfig of rota,
Assemblingthe e
cing weights.
38--
In assembly, the friction and clearances in the axles of the gimbals should be
such that, when. the gyroscope unit is in el to the limit operating angle, the num-
ber of free semioscillations of the gyros ops unit will not be less than four and
not more than seven. For this, the frame is set in a horizontal position. A lower
number of oscillations signifies that the clearance is too small, i. e., the axle
screw (21) (Fig.363) has been firmly tigh ened. If, in checking, it is found that
the clearance is normal but the number of oscillations is less than four, this sig-
nifies that the moment of friction is too high. The pitching scale (22) is mounted
40
42
44_
46.-
48-
50-
52-
54
in such a way that the zero division of t e scale coincides with the center of the
axis of the immature airplane.
Balancing the Gimbal Unit
Balancing the gimbal unit consists in bringing it to a state of indifferent in,-
equilibrium about the axis of rotation of the frame, within the limits of the angle
of suing of the pendulum flaps of the da4er. The balancing is done by shifting the
gyroscope unit along its axis of rotation Changing the total thickness of the gas-
kets (23) (Fig.363) under the frame plug 124).
For the balancing, a device (Fig.373) with ball beari s which have normal
operating clearances is used.
The frame and the gyroscope unit are given different angles of inclination,
while observing the behavior of the unit.
When the device is tapped with a wooden
mallet, a correctly balanced unit will not alter the position it has been given
56--within the limits of the angle of swing of the pendulum flaps.
41
STAT
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When the unit rotates spontaneously,
the direction of this rotation must be de-
tarmined_trom_the_angle of_deviatinn;_thid
and increasing the total thickness of the
6
_JdemonstrAtes thet necPnsity__of-decreasing-
gaskets under the frame plug.
8?Regulating the Instrument
?????..11
10?
Regulating an instrument consists in checking the correct assembly of a sensi.12
-
14--
16--
18__
20__
22__
24--
. 26__
28--
' 30--
--vation, the amount by which the airplane image misses reaching normal position is
32__
established. The error is determined for each individual case.
34
3. The -speed at which the gyro leaves the displaced state can be checked no
36
sooner than 8 miri after it has started operating. The gyroscope unit is deflected
3
by an angle of 300 upward and downward, and then to the right and to the left. The
42 time it takes for the miniature airplane to right itself from any 300 deflection
should not exceed 6 min. The difference 1 time required for it to right itself up-
-ward and downward, or to the right and le)t, should not exceed 2min.
44--
46--
tive part of the instrument and dete g whether its characteristics correspond
to the technical conditions.
In checking, the following technical requirements and conditions must be ob-
served:
1. The time it takes for the niniat e airplane to right itself should be not
more than 2.5 min at normal temperature.
2. The instrument angle of stagnation should not exceed +1 mu at normal tem-
perature. A check is made no sooner than 5 min after the feed has been connected by
tilting the gyroscope to the right, to th
left, upward, and downward; in this obse
40
48-
For regulating an instrument, a device (Fig.373) mounted on a rotary table is
--used. The horizontal position of the axis xx is checked with a level. Air at a
50--
--pressure of 90 pm Hg.is supplied to the device through the aperture in the rod. A
sighting frame, in reference to which the displacement of the aircraft image is ob-r
54
56-iserVed, 2?
is set on the rotary table. The failure of the instrument to correspond to
58:]
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
8?,
1 0 ....???????
.??????11
the tolerances and the technical conditimiswill show up during the original start?
f_the_gyroscope_as_3iell_a-s_irLthe checking process.__Defects
and assembly of the units (not discovered at the proper time and detected only when
ted by regulating.
the gyroscope was operating) must be e
Checking Stagnation in the Instrument
12
Frictionin the gimbal bearing and
14--
the axles of the pendulous vanes will
__have an effect upon stagnation in the ins1rument. Let us examine the angle of stag-
16?
nation due to friction in the gimbal bear
18_
The moment of friction Mfr in the
20_
__opposite to that of the notion, and recov
22_
__the correcting moment Mcor and the momen
24--
r
__the rate of precession returns to zero:
26
L_ 28
' 30
gs.
al bearings always acts in a direction
rywill take place in the rotor axle until
of friction Mfr are in equilibrium aid
a) ? 41,orr Mir _a
/.2
32 The restoring moment of the air jet, which depends on the extent to which the
34 aperture is open, is directly proportional to the angle of aperture of the flaps
36
3
40
if
Mcorr =?a0
1
(18.12)
42 here H0is the maximum restoring moment of the jet when the aperture is Daly open;
?
ao is the angle of deviation of thelflap, corresponding to a fully open
44
46_
48-..-
50
. 52-
54
56
aperture;
a is the angle of deviation of the
of the aperture.
Stagnation will occur when
flap, depending on the degree of opening
Mo
Mcorr--Mjr= ?cto CCI
- - -
113 STAT
wl,s1C
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whence
2
? 4
?
6
1
Mo
ao.
Consequently, the angle of stagnation due to friction in the bearings can be
8 ? '
expressed by
10
12 avt..
14
16 The angle of stagnation due to frict'on in the axles of the flaps was deter-
18 mined by examining the assembly of the da4per housing. It is expressed by
(18.14).
20
22
24 Let us determine the value of the
--
e of stagnation, proceeding.fronLthe
? 26 lowing quantities. Friction in the giMbal bearings Nil. = 0.4 gm-cm.
28 The maximum restoring moment is No = 3.5 gm-cm.
? 30 The angle of deviation of the flap, orresponding to a fully open aperture is
' 0
32 o
= 2.5..
34 The coefficient of friction in the axis of rotation of the flap is ti Er 0.1.
36 The radius of a flap axle is r = 0.5 mm.
3: The distance between the center of gravity of a flap and its axis of rotation
40 is 1= 7.5=6
42
44 at =Aall ?.92-12 5=0,29?.
M00? 3.5
46 __ 0,1 0,5
a , = 7 - 7,5 0,0067 rad = 0,38?.
48
II
51 Sts +CI it.. =0,29+0,38=0,67?.
50
The rotor axle may miss reaching the ertical by this angle. This corresponds
, 5
o the linear value of 0.42 mm on the AGP scale for a 1 =tolerance for the angle
54
56 of stagnation.
58
124
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.-Chec1dngho Instrument for Return of the !Cvroscoje from a Di
L
4.....]
. , It is generally known that the time it takes to return from a 300 tilt should
6-It e_b.etween the_limit_s26_min.__The.!difference_in_tirae_required_f_the_mi ni Om
821.ture airplane to right itself upward and downward or to the right and left, should
1
mamma*
not exceed 2 min.
12__ The rate of precession ia depends upon the correcting moment M
corr
14reaction of the air jets
16--
18__
1
20__ The reaction of the air jets varies Thin the limits of a 2.50 angle from the
22__vertical position to full opening of the aperture. Beyond the limits of this angle,
24--the correcting moment will preserve a constant value so that the rate of precession
26 _will also be constant and the angle of righting in this interval will be expressed
Af corr
=
/0
set up by the
(18.15)
28-
-
30_-
32?
by the formula
M corr I.
--= ? ?
12
(18.16)
34__ A different righting time t at the same angle of tilt, Which is 30?, will sig..
36:-_nify that there are differenttestOring mOiments ticorr. This may be expressed by the
3:-lre1ation5hip
40
42
44
46
48
50
MCOIT1
12 MCOrru
1:-
(18.17)
It is necessary that t1 t2, within !the limits of the tolerance.
A different rate of precession ie explained by different moments of the reac-
ive jets; these may occur as a result of liuneven distribution of the nozzles, dif-
ferent size nozzles, surface roughness, different clearances between the damper
5
ousing and the flaps, and the like. 1
54
56-1 When the parts are accurately executed and the assembling is correctly done,
.58-1
_115_ STAT
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the difference in the time it takes the grroscope to right itself after a tilt lies
2
--wi.thin_the_tolerances stipulated in-the technical cpecifications.--In-some-casesy--
-where the difference in the time it takes the gyroscope to right itself does not lie
8-1
-- can be used under workshop conditions. If the rate of precession co.2 on one end ex-
10?
within the ii Tni ts of the tolerance, the following method of el iminating this defect
ceeds the rate of precession wi on the other end to the same extent as the differ-
1211
- ence in the time of precession exceeds 2min, then the rate of precession can be
14_
compensated by adding a weight to the frame; the weight is so calculated that, as a
16?
result of the moment of inevilibrium, it will equalize the rates of precession.
22L_.
24-
26-
-
20?
. --
30_
Muorr 1
--nain and will set up a precession
-1 32
Rather than adding a weights however, this amount is cut off from the opposite side.
0
The moments VL
-uorr 1 and Ncorr 2 set up the rates of precession W]and (.412; since
(di is less thanw2, .4:14corr 2. Tilhen the weight on the frame is cut to the
extent of P, the frame is unbalanced to the extent of the moment Pt which is added
to Moorr 1?
As the axle of the gyroscope approaches the vertical, this moment PI will re-
a?mini ture airplane will be tilted
34d
sion are equalized, another error
36
3
solder will change the position of the flap and will return the aircraft image to a
40 0
horizontal position. But in this case the system becomes unbalanced. Because of
42
44
46
48
50
5
. 54
56
which will incline the axis of the gyroscope; the
through an angle of a. Once the rates of preces-
will occur, *tilt of the miniature airplane.
This tilt is eliminated by soldering tth on the flaps. The small. weight of this
this, inertia errors will occur when the 4irplane goes into a turn. Such a method
of eliminating this defect cannot be considered correct. To avoid the possibility
of a defect involving the difference in the time it takes the gyroscope to right it-
self, the required accuracy in the executIon of parts and in assembly must be strict
ly maintained.
STAT
1
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
2
Errors Due to Thequllibrium in the Gimbal Rings
? 12_
,
If the center of gravity of a frame (or of a rotor casing) is shifted and a mo-
ment_o_f_unbalanceAnb_acting about _the_axll e_is__Dreat_ed,__tb.e_rptor_capi ne (nr thoN
frame) must be made to precess until the correcting moment Mcorr, increasing as a
result of this inclination, compares with,the moment of unbalance Hb.
As a result, the unbal Puce in the frame will cause the casing to deflect
14_1through an angle 13, which is determined from the condition of unbalance
16?
18_ Midair= Mo rr
c
20_1
22_
24:
26
28--
30_
or
whence
Pi= if an.
-
0
By analogy, if the casing is unbalanced to the extent of limb, the frame will
32_
_ deviate by an angle of.
34
36
3
If one of the moments 14'unb 1 or Hunb ;2 is greater than Ho, there can be no
40
equilibrium and the rotor will be "blocked", since the correcting moment will not be
42
_able to equalize the moment of unbalance and the precession will not
44_
cease.
46?,Errors Due to Oscillation of the Pendulou Vanes
48?
The period of natural oscillation of
the flaps is
50?
52--
_
T =
(18.20)
mga
56
5d
STAT
????????????
140
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
0
?vhereI is the moment of the pend um inertia relative to the axis
3
mass _or. _the. shank;
2?,
44.
6
of swing;
a =Iff. is the distance between the center of gravity and the axis of
Wing;
1 is the length of a flap.
Taking 1 = 20 and substituting the numerical values, we will obtain
T. 27c iuf
^
mit _ 2ir V 2/ _ 2it V 2.2
?0,23 sec.
3mg ?1 3g 3.981
2
?
Under the action of the correcting mOment, the rotor axle will oscillate just
18__
__as the flap does, with the sans period of 0.23 sec.
20I T
-7
__ IetusfindtheamplitudeoftheseescillationsT=6)-011 the supposition
22_
24:11
that one aperture is fully open in the first half of the period and that the rate of
-_precession is constantwo = const = 6?/min. Substituting the numerical values, we
26-
-will get
30_
I
In comparison with the
34__
--the error is insignificant;
36
3
40
42_
44
46
48
50
5
54
aperture will be partially
ate of precession will be
rrors Due to Leaka
I I
0?2 0115?.
2 6
j.
0
1nm:tolerance for the oscillation of the aircraft image
in reality it be still smaller since, aefirst, the
open and since, in calculating, we have assumed that the
at the maximum Lor the entire time.
The assembled instrument should be hermetically sealed; this ensures reliabil-
ty in operation. Jets of air which penetrate inside the instrument when the her-
etic seal is not tight will set up noments of external forces which wiU cancel the
ccuracy of the instrument readings. The Lrmetic seal is checked by producing a
ssure of 500 um water column in the instrument, after which the hose is clamped
ff. The time it takes for the pressure to drop to zero should be not less than
56 '
58
STAT
1
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:at
Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
?20 sec.
Bernetic_seal_is ensured. by,_
a) Using castings without blowholes or cracks;
b) Care in machining the contact faces of the parts;
c) Lubricating the spots where the parts are joined, with a special lubricant;
d) Installing some parts with gaskets or adhesives.
14 Dimensional Analysis
16--
In view of the complexity of
gyroscopic instruments, special emphasis must be
planning the processes of their assembly; such an
analysis permits a more correct solution of
the problems of selecting the most rational
methods of .assembly.
! All this can be demonstrated on the exp..
amPle of dimensional analysis during final
assembly of .che gyro horizon; this is done to
obtain the correct positioning of the lathe
dog relative to the prong; byHmeans of these,
40
49
44
46
48
50
J 5
54
56
Fig.374
this position
is determined
ted to the miniature airplane.
I To do this, we must determine the posi-
till of the cylindrical tip of the lathe dog
relative to the thickness of the prong end;
by the two dimensions a and 0 (Fig.374).
The dimensions a and 0 are
the terminal links in the two dimensional chains.
Let us make an analysis of the tolerances for a concrete example (Table 47).
The calculation to maximum and minium is
.....s.asa.....g."????.???????????.?????????? ?????????.%
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STAT
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_Table 17
Computation Data
-1
1011 12
14
16 -
16_
20._.
22D
24_1
261
nq
30-1
3a:3
40
42
44
a)
b)
d)
Frame
with
gaskets
4,5
41,5
-0,08
-0,2
4,5
41.5
4.42
41,3
4,46
41,4
0,04
0,1
Plate
0,6
138
+0,2
-0,12
0,8
138
0,(6
1,68
(0,7
1,74
9,1 I
11,06 '
Gear.
2,5
0,7
-0,03
-0,09
+0,1
2,4?
0,8
2,41
0,7
2.44
0,75
0,03
-9,05
Prong
1,8
0,3
?0,2
-0,04
2
0,3
1,6
0426
1,8
0,28
0,2
0,02
lathe dog
19
7
3
-0,28
+0,36
?0,5
19
(7,36
3,5
18,72
2,5
18,86
7,18
3
0,14_
0,18
0,5
Rotor casing
33,3
3,5
-.0,17
+0,16
33,3
3,66
33,13
3,5
33,215
3,58
0,085 1
0,08
a) Name; b) Dimensions; c) Conventional sign; d) Nominal; e) Tolerance;
f) Limit dimensions; g) max.; h) min.; 1) Mean size; j) Half tolerance
u
_130_
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
0
4
??????14
10-
12_
?
24-
26 _
28-
30
32
34.
36
3
40
p==g+k-s+p-l-b-t-x-d-Fm-c-fy-r;
=41,5 +45-0,6 +1,8+2,47-0,7-1,6-33,13 +
+ 3,66 18,72 +7,36-.2,5 -4,04;
p 41,3 + 4,42 -0,8 + 1,68 + 2,41 -0,8-1,2-
-33,33 + 3,5-19 + 7-3,5=0,91.
Thus the tolerance for f3 - 60 a. 3013
will be
33,3 -3,5 + 19-41,3 -4,42 +0,8-1,68 -
-2,41 + 0,8 + 2-0,26 = 2,3.3; ?
2.i.= 33,13-3,66 + 18,72 - 41,5 - 4,5 +0,6 -1,8 -
-2,47 + 0,7 + 1,6 -0,3 = 0,52.
Consequently, the tolerance for a - 151 z. 1.81.
I
Let us define the tolerances by another method of dimensional analysis, a meth-
od based on the theory of probabilities i
[ coording to eq.(16.12)].
When no data are available t3n the scattering of*he dimensions, it can be as-
sumed that the -scattering follows the law tofequal probability, according to which
In this case,
a,=0; k = 1,73.
42
44 --1- 15.11,73261= (60,8- 58,325) ? 1,73 V.0,3842 =2,475 4- 1,075.
1,4. The tolerance for - 2,15.
46
48 =(55,325-53,9)?1,73 V0,1022 = 1,425 4- 0,555;
50 2 = 1,98; a ? 0,87. The tottioncejor a - t. = 1,11.
5 As the analysis of tolerances shows, at tolerances of 60 > 3.33 and% > 1.81
54 --the-a.ssemblone by the method-of--full-interchangeability7-abIDavid
56-fronr-the-calculai ti0irtcrilla7d=n3rand-mi-nitffrfriri-
S TAT
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/01/28: CIA-RDP81-01043R002700120001-4
t.
At tolerances of /50 = 2.5 and 6 T5
a = 1-,?ihe assembling cannot be done by the
2 -1.method_of_fr, 1 int erchpn8eshi 11 _case done_by_the method of
?partial interchangeability, which is based on making use of the theory of probabil-
6
8Rities (1. e., for a small percentage the .W.erances of the closing links will go be-
_ yond the required limits So 2.5 and 6a 1.5).
10?
At tolerances of 6 1.5 and oct 4--? 015 in the practical example, the dimension-
12?
_ al chains cannot be solved by either the method of full interchangeability or the
_ method of partial interchangeability, sincle the percentage of tejects will be con-
14_
siderable. In such a case the dimensional analysis can be done by other methods (by
?
18_ l
16?
_matching, by selective assembly, by fittirg, etc.).
20_ In this Chapter, we have emamiexamined.thcl technology for producing special parts
22_
? and the assembly of pneumatic gyroscopic instruments. As far as basic parts and
24-1 ?vnits are concerned, the technology for electric gyroscopic instruments is analogous
26 _-
- to the above-described assembly, with the exception of the electric motor, the
cor-
28-
- mechanism, the current feeds, and some other special parts and units.
30?
_
From the point of view of technology, the manufacture of electric motors is of
32_
___,extreme significance and interest. This problem is examined 34 the next Chapter.
34_
36_
? 38-
40._
42_
46_
48?.
. 50?
ss 52-
54
56
58-
9 STAT
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