Inspection of bevel gears. Instruments for measuring gears. Element-by-element control of gears

To ensure work gear transmission With normal conditions lubrication and without jamming, for each type of mating, a guaranteed gap between the teeth is adopted, which in the transmission can be controlled directly with a feeler gauge or indicator. Control of an individual gear is carried out by the length of the common normal or thickness of the tooth.

Length control general normal is shown in Fig. 96. General normal To two tangent gear profiles To main circle thb and passes through the points 1 And 2, naho



dividing on the dividing circle d and belonging to different tooth profiles. Length control common normal does not require the use of an intermediate base and is carried out using measuring instruments that have plane-parallel jaws, for example gear micrometers (Fig. 97), norm-lamps (Fig. 98), etc.

Along the length of the common normal gear wheels determine the lateral clearance in the transmission. The length of the common normal with the tolerance to the tooth body is indicated in the drawing of the gear. IN general case the length of the common normal is determined by the formula

W- /ge-cos a-[l-(gP - 0,5) +2x-iga + z-invtft],

Where z„ - value of the number of teeth in the length of the common normal, rounded to the nearest whole number; G- number of teeth of the measured wheel; X- displacement coefficient of the original contour; a - engagement angle; A- helical gear profile angle, calculated by the formula A/ = tan a/cos p, where J3 is the angle of inclination of the tooth.

In practice, for an engagement angle of a = 20°, the length of the common normal is determined using tables. According to the table 134 determine the length of the common normal of gears with a module of 1 mm. For other modulus values, the table values ​​should be multiplied by the modulus value of the gear being measured. Length of the common normal in helical teeth
Kommersant

Where b- width of the gear wheel; p is the angle of inclination of the tooth.

In this case, the tabular value of the length of the common normal is determined using the given number of teeth: G" = g-L", where TO- coefficient depending on the angle of inclination of the teeth and determined By table 135. Magnitude TO for intermediate values ​​of the angle of inclination is determined by interpolation: for example, for p = 29°48"

/(= 1,462 + 0,042.- = 1,496.


G

v7

G

6
2

4,5122
61
8

7
2
4,5263
62
8

8
2
4,5403
63
8

9
2
4,5543
64
8

10
2
4,5683
65
8

11
2
4,5823
C6

8

12
2
4,5963
67
8

13
2
4,6103
68
8

14
2
4,6243
69
8

15
2
4,6383
70
9

16
2
4,6523
71
9

17
3
7,6184
72
9

18
3
7,6324
73
9

19
3
7,6464
74
9

20
3
7,6605
75
9

21
3
7,6745
76
9

22
3
7,6885
77
9

23
3
7,7025
78
10

24
3
7,7185
79
10

25
3
7,7305
80
10

26
4
10,6966
81
YU

27
4
10,7106
82
YU

28
4
10.7246
83
to

29
4
10.7386
84
10

30
4
10,7526
85
10

31
4
10.7666
86
10

32
4
10.7806
87
11

33
4
10,7946
88
11

34
4
10,8086
89
11

35
O

13.7748
90
11

36
5
13,7888
91
11

37
5
13,8028
92
11

38
5
13,8168
93
11

39
5
33,8308
94
11

40
5
13,8448
95
11

41
5
13,8588
96
12

42
5
13.8728
97
12

43
5
13,8868
98
12

44
6
16.8530
99
12

45
6
16,8669
100
12

46
6
16.8810
101
12

47
6
16,8950
102
12

48
6
16,9090
103
12

49
6
16,9230
104
13

50
6
16,9370
105
13

51
7
16.9510
106
13

52
7
19,9171
107
13

53
7
19,9311
108
13

54
7
19,9451
109
13

55
7
19,9592
BY

13

56
7
19,9732
111
13

57
7
19.9872
112
13

58
7
20,0012
113
14

59
7
20,0152
114
14

60
7
20,0292
115
14

W

22,9953 23,0093 23,0233 23,0373 23,0513 23,0654 23,0794 23,0934 23,1074 26,0735 26,0875 26,1015 26,1155 26,1295 26,4435 26.1575 26,1715 29,1377 29,1517 29,1657 29,1797 29,4937 29,2077 29,2217 29,2357 29,2490 32,2159 32,2299 32.2439 32,2579 32,2719 32,2859 32,2999 32,3139 32,3279 35,2940 35,3080 35,3220 35,3361 35,3501 35,3641 35,3781 35,392! 38,3582 38,3722 38,3862 38,4002 38,4143 38,4283 38,4423 38,4563 38,4703 41,4364 41,4504 41,4644


G

w

116
14
41,4784

117
14
41,4924

118
14
41,5064

119
14
41,5204

120
14
41,5344

121
14
41,5485

122
15
44,5146

123
15
44,5286

124
15
44,5426

125
15
44,5566

126
15
44,5706

127
15
44,5846

128
15
44,5986

129
15
44,6126

130
16
47,5788

131
16
47,5928

132
16
47,6068

133
16
47,6208

134
16
47,6348

135
16
47,6488

136
16
47,6628

137
16
47,6768

138
16
47,6908

139
17
50,6569

140
17
50,6709

141
17
50,6849

142
17
50,6989

143
17
50,7129

144
17
50,7270

145
17
50,7410

146
17
50,7550

147
17
50,7690

148
18
53,7351

149
18
53,7491

150
18
53,7631

151
18
53,7771

152
18
53,7911

153
18
53.8051

154
18
53.8192

155
18
53,8332

156
19
- 56,7993

157
19
56,8133

158
19
55,827."

159
19
56.8413

160
19
56,8553

161
19
56,8693

162
19
56 8833

163
19
56.8973

164
19
56.9113

165
20
59.8775

166
20
59,8915

167
20
59,9055

168
20
59,9195

169
20
59.9335

170
20
59,9475



Difference

Difference

1,000 1,002 1,004 1,007 1,011 1,016 1.022 1,028 1,036 1.045 1,054 1,065 1,077 1,090 1,104 1,119 1,136 1,154 1,173 1,194 0,002 0,002 0,003 0,004 0,005 0,006 0,006 0,008 0,009 0,009 0,011 0,012 0,013 0.014 0,015 0,017 0,018 0,019 0,021 0,022


21
1,216
0,024
41
2,207
0,096

22
1,240
0,026
42
2,303
0,105

23
1,266
0,027
43
2,408
0,112

24
1,293
0,030
44
2,520
0,121

25
1,323
0,031
45
2,641
0,132

26
1,354
0,034
46
2,773
0,143

27
1,388
0 036
47
2,916
0,155

28
1,424
0,038
48
3.071
0,168

29
1,462
0,042
49
3,239
0,184

30
1,504
0,044
50
3,423
0.200

31
1,548
0,047
51
3,623
0,220

32
1,595
0,051
52
3,843
0,240

33
1,646
0,054
53
4,083
0.264

34
1,700
0,058
54
4,347
0,291

35
1,758
0,062
55
4,638
0,320

36
1,820
0,067
56
4,958
0,354

37
1,887
0,072
57
5,312
0,391

38
1,959
0,077
58
5,703
0,435

39
2.039
0,083
59
6,138
0,485

40
2,119
0,088
60
6,623

In the case when the given number of teeth is not an integer, the additional value of the length of the common normalW is found according to the table. 136.

An example of determining the length of a common normal

Gear parameters: modulem - 4 mm, number of teethz= 23, corner c"-splitting A= 20°, tilt angle teeth R= 29 0 48", displacement coefficientX=0,2.

MeaningTOwe find from the table. 135: TO= 1,486 for P= 29°48". Number of teeth given:z" = Mr. K = 23-1.496 = 34.41. Meaning W = 10,8086 ForG= 34 (according to table 134). Meaning W ■= 0,0057 ForG = 0.41 (according to table 136).

Offset correction: 2-sin RX - 2-0.342-0.2 = 0L368. Amendment V in case of changing the number of teeth ,V girth is 2.9521 (GP - 4 atz - 34, zn =5 at z = 35),

136, Length common normal for the fractional value of a given number teeth (z")


0,00

0,0000 0,0014 0,0028 0,0042 0,0056 0,0070 0,0084 0,0098 0,0112 0,0126 0,0001 0,0015 0,0029 0,0043 0,0057 0,0071 0,0085 0,0099 0,0114 0,0127 0,0003 0,0017 0,0031 0,0045 0,0059 0,0073 0,0087 0,0101 0,0115 0,0129 0,0004 0,0018 0,0032 0,0046 0,0060 0,0074 0,0088 0,0102 0,0116 0,0130 0,0006 0,0020 0,0034 0,0048 0,0061 0,0076 0,0089 0,0104 0,0118 0,0132 0,0007 0,0021 0,0035 0,0049 0,0063 0,0077 0,0091 0,0105 0,0119 0,0133 0,0008 0,0022 0,0036 0,0051 0,0064 0,0079 0,0092 0,0106 0,0120 0,0135 0,0010 0,0024 0,0038 0,0052 0,0066 0,0080 0,0094 0,0108 0,0122 0,0136

OOP 0025 0039 0053 0067 0081 0095 0109 0123 0137 0.0013 0.0027 0.004G 0.0055 0.0069 0.0083 0 0097 0.0Ш 0.0124 0.0139

For a gear wheel t = 1 mm = 55.613 mm.

Control of tooth thickness constant chord Sc (Fig. 99), which is a straight line segment connecting two points of opposite lateral surfaces of a tooth, belonging to the same cylindrical coaxial surface and lines drawn to them from one point of the dividing circle of diameter y. The magnitude of the constant chord Sc in the general case it is determined by the formula

Sc = ^- -ccs2 a + X- sin 2ocj-m,

And the height hc to a constant chord according to the formula /i c = 0.5(d- Sc-tga).

For cylindrical gears with an engagement angle a=20° S c = = 1.38705-m; ft c =0.74758-m.

The thickness of the tooth is measured with an edge caliper (Fig. 99) with a reading on the scales of a ruler, a caliper with micrometric heads (Fig. 100) or a tangential caliper (Fig. 101). The latter are more convenient to use, since the nominal dimensions of the tooth thickness and the position of the measurement line are set with micrometer screws, and the deviation of the tooth thickness is determined using an indicator.

7
=13.9032; for m=4 mmW= 13.9032-4= in most cases carried out By

§ 68. Control of tooth surface roughness

The surface roughness of gear teeth and worm turns depends on the method of their manufacture, and the requirements for roughness are determined by the operating conditions of the gear. Control of the surface roughness of the teeth can be carried out with a double microscope, a profilometer, (a wave meter, and also using reference samples.


In table 137 shows the recommended values ​​of the tooth surface roughness parameters depending on the degree of transmission accuracy.



137. Recommended values ​​of tooth surface roughness (OST 2 N84-1-77)


Cylindrical wheels
Bevel wheels
Worm wheels
Coils of worms

Degree of accuracy
Surface roughness according to GOST 2789-73

wheels
Class
ParameterRa

Class
ParameterRa

Class
ParameterRa

Class
ParameterRa

3 4

6 7 8 9
86 76 66 66
0,40
76
0,80 0,80 1,6

3,2 6,3
96 86 76 76 66 66
0,20

1 ,6
76
0,80

CHAPTER XII. TECHNOLOGICAL PROCESS AND TECHNICAL MEANS OF MECHANIZATION AND AUTOMATION OF GEAR WHEEL PRODUCTION

Rice. 78. Schematic diagram work involutemeters

with replaceable rolling discs

8.7. Control of straightness and direction of the contact line

Control of contact completeness standards consists in the fact that the gear being tested is mated with a measuring one, the side surfaces of the teeth of which are covered with a thin layer of paint (red lead, Turnbull blue, Prussian blue). During mutual single-profile running-in of wheels, traces of paint will remain on the side surfaces of the wheel being tested, in the areas where the profiles meet. These prints are used to judge the quality of the contact line of the gear teeth and the direction of the tooth.

The straightness and direction of the contact line is controlled by a contact meter. The fit of the lateral surfaces of the teeth of the mating wheels must be checked both along the height of the teeth and along their length.

The quality of contact of mating teeth along their length in cylindrical spur wheels is established by monitoring the straightness and parallelism of the direction of the forming teeth to the wheel axis. In helical gears, the fit of the mating surfaces of the teeth along their length is characterized by a helix error (deviation of the tooth direction from the required angle of inclination).

To control the straightness and direction of the contact line of helical cylindrical wheels, contact meters BV-1060 (GOST 5368-58) are used (Fig. 79). These devices are divided into overhead ones, designed to control only the straightness of the contact line without checking the direction of the tooth, and universal contact meters, designed to measure the contact line from straightness and a given direction.

Rice. 79. Straightness control circuit

contact line

The measurement base of the device is the gear rim of the wheel being tested 5, along the cavities of which a support prism 3 attached to the body of the device is installed, having the shape of a straight-sided rack tooth with a profile angle of 40°. The measuring tip of the device 2 with a straight measuring surface is connected to the slide 4 through a spring parallelogram. When measuring the straightness of a tooth, the device slide is moved by means of a rack and pinion gear along the controlled tooth, parallel to the supporting prism, while the non-parallelism of the contact line causes displacement of the tip, recorded by indicator 1.
The diagram for checking the contact line with a universal contact meter is shown in Fig. 40. The gear under test, mounted using a cylindrical mandrel on the center of the device, is turned so that between the wheel axis OO 1 and the direction of movement of the measuring tip in contact with the side surface of the tooth being tested, an angle was formed corresponding to the angle of inclination of the tooth on the main cylinder b 0. In this case, the contact line of the tooth ab will be located parallel to the guide of the base of the device AB, along which the measuring carriage moves (line CD parallel to the wheel axis OO 1, that is, the line of movement of the carriage AB will be located at an angle b 0 to the wheel axle.

Rice. 80. Diagram for checking the contact line

When moving the carriage with the measuring tip along the side surface of the tooth, errors in the direction of the contact line and deviations from straightness will cause the tip to oscillate in a direction perpendicular to the direction of movement of the carriage. These fluctuations are recorded by an indicator or sensor connected to the recorder.

8.8. Tooth direction deviation control

Tooth direction error Fb spur gears can be checked using any testing device that provides the ability to move the measuring unit parallel to the center axis.

The wheel under test is installed with its end face on the plane of plate 2 (Fig. 81) with the tooth cavity resting on the tip 5, mounted on the slider 4. The slider 4 moves along the groove of the bracket 3. The measuring tip 9, which fits into the same tooth cavity, is connected to the rotary lever 7 by means of two leaf springs 8. The springs create rigidity of the tip-lever system in the tangential direction and provide the possibility of some movement of the tip 9 relative to the lever in the axial plane, which reduces the measurement error. Lever 7 is placed on axis 1 in a movable bushing 10, which provides height adjustment of the lever position. The dial indicator is fixed in holder 6 on sleeve 10 and is adjusted to zero using the reference wheel.

Rice. 82. Device with a recorder for monitoring the tooth direction of spur gears

8.9. Monitoring deviations from parallelism and misalignment of shaft axes

Deviations from parallelism and misalignment of the shaft axes are determined in linear units at a length equal to the working width of the gear screw when designing the working axes of the gear wheels onto a plane x(non-parallelism of axes fx) and onto the plane y(axis misalignment fy), passing through one of the axes and perpendicular to the plane in which this axis lies.

8.10. Checking the side clearance standards

The lateral clearance is determined in a section perpendicular to the direction of the teeth, in the plane tangent to the main cylinders.

The standard establishes the smallest guaranteed gap jn min, the value of which does not depend on the degree of accuracy of the wheel, but is determined by the operating conditions of the gear: speed, heating, lubrication.

Guaranteed lateral clearance in the gear is ensured during the manufacture of gears by additionally shifting the gear cutting tool to the center of the wheel being cut by an amount EHS(Fig. 84 a)

8.11. Control of the displacement of the original contour

To determine the displacement of the initial contour of the ring gear of cylindrical spur and helical gears, tangential gear gauges are used. The principle of measuring this parameter using gear gauges is based on the properties of the engagement of the gear with the rack of the original contour. In this regard, the measuring planes of the tangential gear gauge are made in the form of a supporting prism with an angle of 2a, that is, 40°, formed by jaws 1 and 3 (Fig. 83).

Rice. 83. Circuit for measuring the displacement of the source

contour with a tangential gear gauge

The measurement base for tangential gear gauges is usually the circle of the lugs of the wheel being tested, relative to which the position of the original contour is determined.

To determine the magnitude of the radial displacement of the original contour, the tangential gear gauge is equipped with indicator 2, the axis of the rod of which is the bisector of the prism angle. Since the side surfaces of the tangential gear gauge represent the profile of a gear rack, when the gear gauge is applied (after preliminary installation according to the sample) to the tooth of the wheel being tested, the contact points will be located on the engagement lines in exactly the same way as when the rack and wheel are engaged without backlash (Fig. 84, a, b).

Rice. 84. Tangential gear gauge GOST 4446-59:

a) measurement scheme; b) general form; c) tuning diagram

The tangential gear gauge (Fig. 84, c) consists of a body 4, to which a collet 5 is attached for installing an indicator 6 with an extended tip 8. The measuring jaws 1 and 2 of the device are driven by a common screw 3 with right-hand and left-hand threads. This makes it possible to move both jaws in opposite directions at the same time. The jaws are moved by turning the screw head. In the desired position, the jaws are fixed with stoppers.

A tangential gear gauge is a relative measuring device. Preliminary installation of the tangential gear gauge is carried out according to installation sample 7, which is usually used as calibrated rollers of a certain diameter.

When installing a tangential gear gauge along a roller, the diameter required for this dp roller is determined by the formula

, mm,

Where kp– coefficient depending on .

For = 20° k= 1.2037. In this case dp = 1,2037m.

The diameter of the installation roller depends only on the module and the angle of the initial contour, but does not depend on the number of teeth of the wheel being tested.

8.12. Tooth thickness control

Control of tooth thickness deviations along a constant chord Sc and tooth height to constant chord hc carried out with a tangential gear gauge (Fig. 84, b). In this case, the jaws of the tangential gear gauge are adjusted to the nominal size of the tooth thickness along a constant chord, and the recording device is set to the zero mark.

The shift of the indicator arrow during tooth measurement from zero to the right (plus) indicates a decrease in thickness S of the tooth being tested DS(Fig. 85, a) and, conversely, a shift of the indicator arrow from zero to the left (minus) indicates an increase in the thickness of the tooth (Fig. 85, b). When the indicator needle is set to the zero division, the checked tooth thickness is equal to the nominal value (Fig. 85, c).

When measuring the corrected gears with a tangential gear gauge, you can determine the displacement coefficient of the original contour:

Where Dh– deviation of tooth height from a constant chord;

m– module.

When measuring corrected gear wheels with angular correction using a tangential gear gauge, it is adjusted using installation samples (rollers or measuring wheels) intended for measuring uncorrected gear wheels, but the gear gauge readings should be corrected (the amount of reduction in the radius of the circle of the gear protrusions), by which the gear gauge readings needs to be reduced.

When measuring wheels with height correction, no correction is introduced, since for wheels with height correction the radius of the circle of the protrusions changes by an amount equal to the shift of the original contour of the cutting tool, since .

Rice. 85. Indications of a tangential gear gauge:

a – when measuring thinned teeth;

b – when measuring thickened teeth;

c – when measuring normal theoretically accurate teeth

8.13. Monitoring the parameters of bevel gears

The kinematic error of bevel gears can be determined using single-profile instruments, the operating principle of which is the same as that of single-profile instruments for checking this indicator for cylindrical gears. IN in this case The instantaneous transmission ratios and movements of the driven link of the gear pair are continuously compared with those of a transmission with precise friction cones. The disadvantage of devices operating according to this scheme is the need to have precise cones for each pair of controlled wheels in accordance with their gear ratio.

8.14. Monitoring the accumulated circular pitch error

bevel wheels

The accumulated error in the circumferential pitch of bevel wheels is the difference in circumferential pitches and the maximum deviations of this parameter can be determined using a special device (Fig. 86).

The gear wheel 1 being tested is installed on the support ring 2 and centered on it. For ease of rotation, a separator with balls is installed on the upper part of the support ring. During the measurement process, tips 3 and 5 are adjusted so that they do not touch the same sides of two adjacent teeth of wheel 1 approximately in the middle part along the length of the tooth. The uniformity of the circumferential pitch is established by turning the gear sequentially from one pair of teeth to another, carried out by cam 4. The difference in any circumferential steps is equal to the difference in the reading of the indicator associated with the movable tip 5.

Checking the bevel gear shaft on this device is carried out when secured in the centers.

Rice. 86. Device for measuring a conical circular ball

gear wheels

Monitoring the circumferential pitch error of bevel gears essentially replaces the control of the main pitch of engagement, which cannot be checked for these wheels due to the fact that the side surface of the tooth of bevel gears is not an involute.

8.15. Monitoring the axial movement of bevel gears

The axial movement of bevel gears in tight mesh can be detected using two-profile instruments (Fig. 87).

In this case, the controlled wheel is mated with the measuring one, in which the thickness of the tooth must be increased by the amount of the average thinning provided for the wheel under test; in this case, strict coincidence of the vertices of the initial cones is necessary, since in this case the teeth will touch along their entire length, that is, there will be their full longitudinal contact is ensured.

Rice. 87. Checking the axial movement of conical

gear wheels in a dense two-profile

engagement on the intercentromere

To be able to control bevel wheels on two-profile instruments (Fig. 87), they are accompanied by a special bracket 5, mounted on the installation carriage of the device 6. The bracket has a vertical carriage 2 with a horizontal mandrel 1. The movement of the carriage 2 is carried out by a handwheel 3. Having achieved the movement of the measuring carriage 8 tightly wheel alignment, determine the oscillation of this carriage when the wheels rotate per wheel revolution and when the measured wheel is rotated by one tooth. The axial movement of one of the mating wheels in tight engagement is associated with the fluctuation of the measuring center angle by the following relationship:

,

where is the angle of the pitch cone of a gear or wheel (see Fig. 63).

8.16. Control of gear radial runout

bevel wheel crown

The radial runout of the bevel wheel gear is controlled by bevel gauges (Fig. 88). The device consists of a base 6, on which a plate 8 is hinged. A mandrel 4 is fixed to the base of the device, on which the bevel wheel being tested is fixed. A tip 3 connected to a recording device 5 is inserted into the depressions between the teeth along the average diameter of the bevel wheel (that is, in the middle of the width of the tooth). The position of the tip 3 can be adjusted by the location of the plate and rack and pinion gear located in guide 2 (dovetail-shaped).

As a measuring tip, to control runout, conical and ball tips are used, similar to those used to control cylindrical gears.

Rice. 88. Run-out gauge for bevel gears

To control the radial runout of the ring gear of bevel wheels, a special device is used (Fig. 89).

The device consists of a body 1, made in the form of a rectangular strip with a groove and a base prism. A movable frame 3 is installed on the rectangular bar of the case, in which the holder 2 is fixed, which fits into the groove of the case 1. The dial indicator is fixed in a holder. The holder 6 is fixed on the axis of the holder 2, so that it is possible to install the holder at the required angle of inclination D. Position of the holder fixed with screw 4.

Rice. 89. Device for controlling radial

runout of the ring gear of bevel wheels

The device is equipped with a set of replaceable tips 7, the dimensions of which are calculated depending on the wheel module. When checking runout, the device is based on the diameter and supporting end of the wheel being tested, and the measuring tip is alternately inserted into the tooth cavities. The bevel gear is mounted on a mandrel and mounted on the centers.

8.17. Checking the measuring side clearance of bevel wheels

The control of the measuring lateral clearance of bevel wheels is carried out on control and rolling machines when the controlled wheel 2 is mated with the measuring wheel 1.

The measuring lateral gap is determined using a dial indicator 3 mounted on the machine body. When the drive wheel is stationary, turn the driven wheel in both directions, determining the maximum deviation using the indicator (Fig. 90).

Gear designation.

  • 8 - 7 - 6 - Va GOST 1643 - 81.
  • 8 - degree of kinematic accuracy.
  • 7 is the standard for smooth operation.
  • 6 - norm of tooth contact.

B - type of pairing.

a - type of tolerance for lateral clearance.

  • 12 degrees of accuracy 1,2,3,4,5,6,7,8,9,10,11,12. 12 is the roughest.
  • 6 types of pairing. A, B, C, D, E, H.

Figure 23


Figure 24 Basic parameters of the tooth.

d - pitch circle - a circle that is the basis for determining the elements of the teeth and their sizes.

Circumferential tooth thickness- the distance between opposite tooth profiles along the arc of the concentric (pitch, initial) circle of the gear.

Tooth thickness along the chord (width of the cavity along the chord)- chord length between unlike tooth profiles along the pitch circle.

Figure 25

The thickness of the tooth is controlled by a caliper gauge. By vertical rod set aside the specified tooth height. And we measure the thickness of the tooth using a horizontal rod.

Basic step.

Figure 26 Basic pitch measurement diagram.

The main pitch of the gear is controlled by a main pitch pedometer.

From the end length measures we collect a block equal to the size of the main step. We set the pedometer to 0. We bring the fixed sponge of the pedometer to the tooth profile, and with the movable sponge we roll the profile of another tooth, shaking it, we find the greatest deviation from 0.

The main pitch can be checked on a microscope by centering the gear. Then, working with only one microscrew and turning the table, we bring the tooth profile head to the crosshair of the eyepiece head and take the first measurement. Then, working only with the same microscrew, we bring the next tooth to the crosshair until it touches and take the 2nd measurement. The difference between these measurements is the value of the main step.

The main pitch difference is determined by measuring all the main pitches of one gear.

Profile tooth

Figure 27 Scheme for measuring tooth profile

The error of the tooth profile is controlled on an involute meter by running along the active profile of the tooth involute.

Length of the common normal.

Figure 28

The length of the common normal is controlled by a gear micrometer, normal gauge. with the number of teeth specified in technical conditions. Using a gear micrometer we measure the actual length of the common normal. When checking with a standard gauge, we set the gauge block to 0, measure the part and look at the deviation from the length of the general normal.

Figure 29 Gear micrometer

Figure 30 Indicator normal gauge

Radial runout of the ring gear.


Figure 31

The radial runout of the ring gear is controlled at a radius close to the pitch circle. We select the spherical insert so that the sphere of the insert touches the tooth profile approximately at the diameter of the pitch circle.

The direction of the tooth can be checked using an involute meter VG-450 Karl-Zeiss, a beat gauge, a measuring machine, or a surface plate. We fix the gear with its base surface into a prism, and install this prism with an emphasis on another prism. We set the measuring head to zero on the tooth profile, moving the prism with the gear we find the difference in readings - this is the deviation of the tooth direction. The direction of the gear tooth is controlled from both sides, each tooth.

Size according to rollers (balls) M.

The distance between the surfaces of two cylindrical rollers (balls) along the common normal to the surfaces touching the main lateral surfaces of the teeth, while in the end section the symmetry axis of the depressions in which the rollers (balls) lie constitutes angles equal to 180° and 180°, respectively, for even and an odd number of teeth.

Goal of the work

Study the principle of operation and structure of gear gauges and master the technique of measuring the dimensions of gear elements with a caliper and a micrometric gear gauge.

Material support

1) Vernier gauge type ___________, No. ___________, factory ___________, with measurement limits ____________ mm, vernier scale division value ________ mm, measurement error __________ mm.

2) Vernier caliper type ___________, No. ___________, factory ___________, with measurement limits ____________ mm, vernier scale division value ________ mm, measurement error __________ mm.

3) Micrometric gear gauge type ___________, No. ___________ factory ___________, with measurement limits _____________ mm, drum scale division ________ mm, measurement error __________ mm.

4) Gears.

1. Theoretical provisions

1.1. General information about gears and methods of their inspection

A gear wheel is a rather complex product. Its quality is largely determined by the accuracy of a number of parameters, depending on the technical condition of gear-processing equipment, the level of technology, the quality of the cutting tool and the quality of control and measurement operations of gear-processing production.

The accuracy requirements for most parameters of gears are not the same and depend mainly on the specific purpose of the wheels and the transmission as a whole. For machine tool speed boxes and precision instruments, particularly high demands are placed on parameters characterizing the accuracy of motion transmission, i.e. kinematic accuracy. In high-speed transmissions, the parameters that determine smooth operation, which reduces noise, vibration and wear. For power transmissions, it is important to strictly adhere to the parameters that affect the conditions tooth contact. In order to compensate for some manufacturing errors, real gears have a gap between the non-functioning surfaces of the profiles, which is called side clearance. The significance of this gap is especially large for gears operating under conditions of large temperature fluctuations and in reversing mechanisms.

In GOST 1643 – 81 “Cylindrical gear transmissions. Tolerances" all requirements for ensuring the accuracy of gear parameters are divided into four groups, which are called accuracy standards. GOST provides norms of kinematic accuracy, norms of smoothness, norms of tooth contact and norms of lateral clearance. In the first three groups, tolerances for specific parameters are established depending on the degree of accuracy. There are 12 degrees of accuracy in total. However, the standard specifies the values ​​of parameters only from 3rd to 12th, and the most accurate, 1st and 2nd degrees, are left as reserves.

In the manufacture of gears, their quality is ensured by both a high level of final (acceptance) control and other organizational and preventive measures - preventive, technological and active types of control.

At final control establish whether the accuracy of the manufacture of gears corresponds to the operating conditions of the transmission.

Preventive control consists of checking the condition of technological equipment: machines, fixtures, cutting tools. It must be carried out before the production of gears begins.

Technological control consists of element-by-element control of gears. It allows you to establish the accuracy of individual elements of technological equipment and, if necessary, take timely measures to eliminate defects.

Active control is that one or more parameters are measured during processing. Using the measurement results, the technological process is controlled, for example, the processing process is interrupted when the required size is reached.

Preventive, process and active control must precede final (acceptance) control.

1.2. Element-by-element control of gears

The devices used for element-by-element (differentiated) control are divided by design into overhead (H) and machine-mounted (C).

The first to be checked are, as a rule, large-sized parts that are difficult to install on machine tools. However, due to the fact that the base for overhead devices is the circle of the wheel protrusions, and not the operational base (wheel hole or gear shaft), their error is greater than that of machine tools.

Element-by-element control consists of checking the compliance of the values ​​of individual parameters with the requirements of the standard. The data obtained from differentiated control of gears allows for prompt adjustment of process equipment to prevent possible defects.

Checking the radial runout of the ring gear, which characterizes part of its kinematic error, is carried out using special devices called beat gauges. The schematic diagram of the measurement is shown in Fig. 1, A.

Rice. 1. Schemes for measuring the radial runout of gear rings:

A principled; b) in workshop conditions; V internal gear wheels

Measuring tip 2 , made in the form of a truncated cone with an apex angle of 40°, is inserted into the cavity of the gear wheel 7 . From the measuring head 3 take readings. Then, moving the carriage 4 and turning the gear wheel, insert the measuring tip into each subsequent depression. The radial runout value is taken equal to the difference between the largest and smallest readings of the head per revolution. The device also allows you to control bevel gears.

In workshop conditions, control of the radial runout of the ring gear 7 (Fig. 1, b) can be carried out using control centers 5 And 9 , calibrated roller 10 , stand 11 with measuring head 8 and mandrel 6 . To do this, the gear is put on a mandrel and installed in the centers using center holes. A roller is sequentially placed in the wheel depressions and a reading is taken on the head scale. The value of radial runout is determined in the same way as on a bienimer.

To measure the radial runout of the inner ring gear of a wheel 13 (Fig. 1, V), use a tip 12 spherical shape. Radial processing errors can be detected using spherical tips and rollers only with the most favorable diameter.

Radial runout of the ring gear occurs due to the variability of the distance between the gear and the tool processing it. To reduce this error, it is necessary to check and eliminate the radial runout of the workpiece on the mandrel before installing it on the gear cutting machine. Radial runout of the cutting tool is observed much less frequently.

Fluctuation of the length of the common normal W controlled by instruments that have two parallel measuring surfaces and a device for measuring the distance between them.

The length of the common normal can be measured using the absolute method using micrometric gear gauges of the MZ type (Fig. 2, A) with a division value of 0.01 mm and measurement ranges of 0...25; 25...50; 50...75 and 75...100 mm.

Rice. 2. Micrometric tooth gauge ( A), normal gauge ( b), spherical tips ( V) and limit caliber ( G) to control the length of the common normal

Measuring the length of the general normal (as well as its vibrations) by comparison is carried out using a normal meter (Fig. 2, b), which has two measuring jaws - the base 5 and mobile 1 . The latter is connected by a transmission mechanism to the measuring head 2 . Base jaw with split sleeve 3 mounted in the required position on the rod 4 when setting the device to zero using the gauge block. Movable sponge 1 retracted with a arrestor. The jaws cover a row of teeth, then the measuring jaw is released and the deviation of the length of the common normal from the nominal value is read from the scale.

Using spherical measuring tips (Fig. 2, V), you can measure the length of the common normal by direct estimation or determine its deviation from the nominal value by comparison. Universal gear measuring instruments are used as measuring instruments.

In conditions of large-scale and mass production, control of the length of the general normal is carried out using limit gauges (Fig. 2, G).

The meshing pitch (main pitch) is measured by determining the distance between two parallel planes tangent to the two working surfaces of the same name of adjacent gear teeth. In the example under consideration, measurements using a clip-on pedometer are parallel to the planes in which the measuring tips lie 1 And 4 (Fig. 3, A).

Distance P measured along the line ah-ah. Movable measuring tip 1 via linkage 2 connected to the measuring head 3 . Tip 4 motionless and basic. Before measurement, the device is set to zero using a special device. During the measurement process, the device is rocked relative to the support tip. 5 . The deviation of the engagement pitch value from the nominal value is taken as the minimum reading on the head scale 3 .

Control of step uniformity consists in determining deviations of the actual step from the average value. For this purpose, overhead devices are used. The gear pitch must be measured at a constant diameter. For this purpose, the device is equipped with special adjustable support tips. 7 And 10 (Fig. 3, b), with the help of which it is based on the cylindrical surface of the teeth. The device has two measuring tips - movable 6 and motionless 11 . The movable tip transmits pitch deviations through a linkage 8 to the measuring head 9 . Before measurement, the device is set to zero at one of the pitches of the gear being tested. The device allows you to measure both the difference between adjacent pitches and the accumulated error of gear pitches. Overhead pedometer (Fig. 3, V), except for the mounting stop 13 , resting on the cylindrical surface of the teeth, is equipped with two more stops 12 , basing the device on the end surface of the gear wheel. The pedometer has movable and fixed flat tips 14 . The measurement is carried out in the same sequence.

Rice. 3. Schemes for measuring the pitch of engagement ( A) and control of its uniformity ( b) using a clip-on pedometer ( V)

Uneven pitch affects the smooth operation of the wheel. Typically, this error occurs due to the inaccuracy of the tool used when machining wheels using the rolling method, or due to inaccurate adjustment of the machine's dividing chain when machining using the dividing method.

Measuring the tooth profile error is carried out with special devices - involute meters. The measurement is based on the principle of continuous comparison of the model involute reproduced by the device with the actual profile of the measured wheel. According to the method of reproducing an exemplary involute, devices are divided into individual disk and universal.

The individual disk involute meter (Fig. 4) has a replaceable disk 4 , the size of which is equal to the diameter of the main circle of the wheel being tested.

The wheel being tested is mounted on the same axle as the disk. 3 . The disk is pressed against the working surface of the ruler by springs 2 mounted on the carriage 7 . When moving the carriage with a screw 1 a ruler in contact with the disk will rotate it around its axis without slipping. In this case, any point on the disk moves relative to the corresponding point on the surface of the ruler along an involute. Measuring tip of the lever 6 is in the plane of the working surface of the ruler. If the actual tooth profile differs from the involute, then the tip is deflected, and using the measuring head 8 The tooth profile error is recorded. Scale 9 helps to quickly return the measuring tip to its original position and set it along the diameter of the main circle; it also monitors the movement of the carriage. Using a scale 5 evaluate the rotation angle of the wheel being tested. To control the next tooth, turn the wheel by one angular step, and the carriage, using the scale 9 , move to the original position. To measure the profile on the other side of the tooth, the wheel being tested is turned over on a mandrel. The main disadvantage of the device is the need to have its own disc for each controlled wheel, different from the previous one being tested. Therefore, an individual disk involute meter is used only in large-scale and mass production conditions.

In small-scale and individual production, it is more advisable to use universal devices with a constant rolling disk, involute cam or other devices that ensure the reproduction of the theoretical involute. The use of inductive sensors instead of a measuring head allows profile deviations to be recorded on a diagram.

Rice. 4. Individual disk involute meter

Large wheels (straight and helical) are measured with overhead involute gauges.

1.3. Purpose and design of the caliper and

tangential gear gauge

One of the main indicators that determine the lateral clearance of a pair of cylindrical wheels is tooth thickness along the chord, measured with tooth gauges. By design, these devices are divided into overhead and machine-mounted ones, and according to the principle of operation - into caliper gauges and indicator-micrometric tooth gauges.

Vernier gauge(Fig. 5, A) has two scales – 5 And 1 : the first is for measuring thickness S tooth using a vernier 4 , and the second - for setting the device jaws to the required height h from the top of the teeth. Before measuring, stop 3 set according to vernier 2 to a size equal to the height h, and secured in this position. Then spread the measuring jaws and, after installing the device, focusing on the outer surface, measure the tooth thickness along the chord, counting its full value directly on the scale 5 and vernier 4 . The disadvantages of the vernier gauge are the low accuracy of reading along the vernier, rapid wear of the measuring jaws, and the influence on the measurement accuracy of the error in positioning the device along the circumference of the protrusions.

The counting method is similar to the method for taking the result using a barbell instrument, but the division value of the main scale (on the barbell) is 0.5 mm.

Tangential tooth gauge type NC (Fig. 5, b) control the thickness of the tooth by the displacement of the original contour. The reference base for measurements is the circumference of the protrusions. Measuring surfaces of two jaws 11 make up a double engagement angle of 40. The axis of the measuring rod bisects this angle. The measuring jaws are moved in the housing guides 6 screw 10 , having sections with both right-hand and left-hand threads. This ensures symmetrical installation of the jaws relative to the axis of the measuring rod of the head 9 . The jaws are secured with locking screws 7 . The spherical measuring tip is attached to the head rod with a clamp 8 .

Before measurement, the device is adjusted to size using a reference roller, the diameter of which is 1.2036 m, Where m– module of the wheel being tested. The tooth gauge is placed on the roller, then moved with a screw 10 sponges 11 , bring the measuring tip into contact with the roller and create a preload of the tip by one or two turns of the arrow. After this, the scale is set to zero. During inspection, measuring jaws, reproducing the side profile of the cavity of the original rack, are placed on the tooth 12 and by the deviation of the indicator, the displacement of the actual initial contour relative to the nominal position is judged.

Rice. 5. Dental gauges:

A vernier gauge; b tangential gear gauge


2. Work order

1. Study the design, principle of operation of caliper gauges and micrometric tooth gauges of the MZ type.

2. Determine and record in the report the metrological characteristics of the caliper and micrometric gear gauges.

3. Draw a diagram for measuring the thickness of a gear tooth and measuring the length of the common normal of a gear.

4. Determine half the height of the tooth h according to the formula

h = ,

Where D max – diameter of the tops of the wheel teeth; D min – diameter of the wheel dimples.

5. Measure the thickness of ten teeth of each gear.

6. Measure the length of the common normal of the gears with a micrometric gear gauge.

7. Enter the measurement results into tables (Tables 1, 2).

Table 1. Results of measuring tooth thickness along the chord

Dimensions, mm

gear wheel 1

gear wheel 2

Table 2. Results of measuring the length of the common normal

8. Define a module m gears according to the formula

Where D d– diameter of the pitch circle of the gear wheel; z– number of teeth.

The diameter of the pitch circle is calculated as

D d = .

9. Determine the lateral clearance of the gear teeth 1 And 2 and compare with the standards of GOST 1643 - 81.

10. Finalize the report, which should end with conclusions on the work.

3. Contents of the laboratory report

1. Number, name, purpose, material support of laboratory work.

2. Purpose and design of the measuring instruments in question.

3. Scheme for measuring the thickness of the tooth along the chord and the length of the common normal of the gears.

4. Table with measurement results (see tables 1, 2).

5. Conclusion laboratory work.

4. Instructions for preparing the report

The laboratory report is completed on standard sheets of white A4 paper (210 x 297 mm) with a standard frame. Requirements for drawing a frame: left indent 20 mm; top, right and bottom – 5 mm. The first page is designed as a title page. At the bottom of each subsequent sheet, a corner stamp is drawn to indicate the sheet number. When writing an explanatory note on a computer, it is allowed not to create a frame. The font used is Times New Roman, size 14, line spacing 1.5.

Control questions

1. What refers to the metrological characteristics of measuring instruments?

2. What methods are used in measurement processes?

3. What are the main parts of a caliper and micrometric gear and what are they intended for?

4. What is the measurement technique with a caliper and micrometric gear?

5. What accuracy standards for gears are established by the standard?

6. List the main types of control of gears.

7. By what means and how are deviations and the length of the common normal measured?

8. What instruments and how can you check the indicators that determine the lateral clearance in the gearing?

Bibliography

1. Makhanko A.M. Control of machine tools and metalwork. – M.: graduate School, 2000. – 286 p.

2. Ganevsky G.M., Goldin V.E. Tolerances, fits and technical measurements in mechanical engineering. – M.: Higher School, 1998. – 305 p.

3. GOST 1643 – 81. Cylindrical gear transmissions. Tolerances.

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