Equal division detector for ball way of inner ring of transmission shaft

Abstract

A clamping device, an orienting device, a contact device and a measuring device are installed on a working table plate, the lower portion of a pull rod of the clamping device is in spiral connection with an expansion sleeve, the outer conical surface of the pull rod is in sliding connection with the inner conical surface of the expansion sleeve, and the front end of a guide rod A of the orienting device is fixedly connected with a steel ball A; a steel ball A is in contact positioning with a ball groove under the action of a spring A. A bolt C of the contact device penetrates through a support B to be fixedly connected with an upper limiting plate, a bolt D penetrates through the support B to be fixedly connected with a lower limiting plate, a steel ball B is located between the upper limiting plate and the lower limiting plate which are opposite to each other, and the steel ball B is in contact with the adjacent ball groove. The measuring device comprises a swing part, a cylindrical ring and a dial indicator. The swing piece is in tangent contact with the steel ball B. A dial indicator is installed on the support D, and a measuring head on the dial indicator is opposite to the swing piece. By using the technology, when the inner ring ball way equal division is measured, the adjustment is convenient, the efficiency is high, and the detection precision of the inner ring ball way equal division can be ensured.

Description

Technical Field

[0001] The invention relates to a measuring instrument for equally dividing a ball track, in particular to a detection instrument for equally dividing a ball track inside a transmission shaft. Background Art

[0002] The drive shaft of the car constant velocity universal joint is composed of a fixed end joint, an intermediate shaft and a movable end joint, wherein the fixed end joint is directly connected to the wheel hub of the car wheel, and the movable end joint is directly connected to the differential of the engine. The power of the engine is transmitted to the wheel through the differential, the movable end joint, the intermediate shaft, the fixed end joint and the wheel hub, thereby driving the wheel to rotate. The fixed end joint is mainly composed of an outer ring, a retainer, a steel ball and an inner ring; the movable end joint is mainly composed of an outer sleeve, a retainer, a steel ball and an inner sleeve. The ball track of the inner ring is matched with the ball track of the outer ring through the steel ball. The ball track of the inner ring is completed by hard milling or grinding. The precision requirement is high. If the equal division accuracy of the ball track of the inner ring is not qualified, it will cause the inner ring track to not meet the technical specification requirements through the steel ball and the outer ring track, which is easy to wear, shorten the service life of the inner ring, and cause jamming and abnormal noise. In the past, the ball lane division of the inner ring was measured by three-coordinate measurement, but the measurement cycle was long and the efficiency was low. The production had to be stopped to wait for the three-coordinate measurement results, and the three-coordinate resources were occupied, which was a great waste. At the same time, a considerable number of companies believed that the ball lane division of the inner ring was guaranteed by program processing. In fact, with the changes in equipment accuracy, the wear and adjustment errors of the fixtures, the wear of the cutting tools, etc., the inner ring ball lane division has out-of-tolerance conditions, and it is a potential defect that is difficult to find. The out-of-tolerance of the ball lane division will directly lead to the assembly of the fixed end section being stuck and making abnormal noises, and the production needs to be stopped to wait for the problem to be solved. A considerable number of companies have experienced this. Therefore, an instrument that can measure the inner ring ball lane division efficiently and conveniently and can ensure the measurement accuracy is urgently needed at the processing site. Summary of the invention

[0003] The purpose of the present invention is to provide a transmission shaft inner ring track equal division detector, using this technology, when measuring the inner ring track equal division, not only is it convenient to adjust, the efficiency is high, but also the detection accuracy of the inner ring track equal division can be guaranteed.

[0004] The technical solution of the present invention is: a transmission shaft inner ring track equal division detector, including a pillar, a worktable, the worktable is fixedly connected to the pillar, a cylindrical guide hole is provided on the worktable, a clamping device, an orientation device, a contact device, and a measuring device are installed on the worktable, the clamping device includes an expansion sleeve, a pull rod, a bolt A, a support block, and a bolt B, the expansion sleeve is slidably connected to the cylindrical guide hole on the worktable, a positioning boss is provided on the expansion sleeve, an inner conical surface is provided in the expansion sleeve, a threaded hole is provided at the lower part of the expansion sleeve, the pull rod is installed in the expansion sleeve, a threaded rod portion A is provided at the lower part of the pull rod, the threaded rod portion A of the pull rod is spirally connected to the threaded hole of the expansion sleeve, and an outer cone is provided on the pull rod The outer conical surface is slidably connected with the inner conical surface, the bolt A passes through the workbench and is fixedly connected with the support block installed in the cylindrical guide hole, the support block contacts the expansion sleeve, and plays a role in adjusting the height of the expansion sleeve, the bolt B passes through the workbench and is threadedly connected with the expansion sleeve, and is used to position the expansion sleeve and the support block close together; the directional device includes a bracket A, a guide rod A, a nut A, a steel ball A, and a spring A, the bracket A is fixedly connected with the workbench, the bracket A is provided with a hole A, the guide rod A is slidably connected with the hole A, the guide rod A is provided with a cylindrical boss A, the tail end of the guide rod A is provided with a threaded rod B, the nut A is spirally connected with the threaded rod B, and the guide The front end of the guide rod A is fixedly connected to the steel ball A, and the spring A is sleeved on the guide rod A and is located between the cylindrical boss A and the bracket A; the contact device includes a bracket B, a bolt C, an upper limiting plate, a pin B, a bolt D, a lower limiting plate, a pin A, a steel ball B, a guide rod B, a nut B, and a spring B. The bracket B is fixedly connected to the workbench, the bolt C passes through the bracket B and is fixedly connected to the upper limiting plate, the pin B is fixedly connected to the bracket B and the upper limiting plate, the bolt D passes through the bracket B and is fixedly connected to the lower limiting plate, the pin A is fixedly connected to the bracket B and the lower limiting plate, the upper limiting plate and the lower limiting plate have the same structure, and the lower limiting plate has a lower bottom surface and a lower limiting inclined surface. The upper limiting plate has an upper bottom surface and an upper limiting inclined surface, the steel ball B is located between the two opposite upper limiting plates and the lower limiting plate, and can slide between the upper and lower limiting plates, the upper limiting inclined surface and the lower limiting inclined surface are used to prevent the steel ball B from falling off, the guide rod B is supported by the bracket B, the bracket B is provided with a hole B, the guide rod B is slidably connected with the hole B, the guide rod B is provided with a cylindrical boss B, the cylindrical boss B is opposite to the steel ball B, the steel ball A and the steel ball B are in the same horizontal plane, the tail end of the guide rod B is provided with a threaded rod C, the nut B is spirally connected with the threaded rod C, and the spring B is sleeved on the guide rod B and is located between the cylindrical boss B and the bracket B;The measuring device comprises a bracket C, a bracket D, a rotating shaft, a swinging member, a cylindrical ring, a support block, a bolt E, a nut C, a spring C, a micrometer, and a screw. The bracket C and the bracket D are respectively fixedly connected to the workbench. The rotating shaft is fixedly mounted on the bracket C. The swinging member is provided with a cylindrical ring. The swinging member is rotatably connected to the rotating shaft through the cylindrical ring. The swinging member is provided with a through groove. The bracket C is fixedly connected to the support block. The bolt E passes through the through groove on the swinging member and is fixedly connected to the support block through a spiral connection with the nut C. The spring C is sleeved on the bolt E and is located between the support block and the swinging member. The function of the spring C is to make the swinging member tangentially contact with the steel ball B by elastic force. The bracket D is provided with a micrometer. The dial gauge rod is fastened to the bracket D (23) by a screw. The micrometer is provided with a probe, and the probe is opposite to the swinging member. ;

[0005] The principle of the present invention is: first, mark the inner ring whose inner ring track division value meets the limit sample requirement after three-coordinate measurement, and measure the center of the inner ring track as the inner ring limit sample, record the measured value and follow the inner ring limit sample. The inner ring limit sample is the one where the difference between the maximum and minimum values ​​of the inner ring track division is the same as the difference between the upper and lower limits of the division required by the design. The height of the expansion sleeve is adjusted by bolts A and bolts B so that the center of the inner ring track is on the same horizontal plane as steel balls A and B: the center value of the limit sample track + the distance from the positioning boss to the workbench = the distance from the center of steel ball B to the workbench. The inner hole of the inner ring limit sample is mounted on the expansion sleeve so that the reference surface of the inner ring limit sample is close to the positioning boss. The steel ball A is in contact with the ball track of the inner ring limit sample under the elastic force of spring A, so that the inner ring limit sample is positioned circumferentially. The pull rod is rotated by the inner hexagonal sinker to tighten the inner ring. The steel ball B is in contact with and close to the adjacent ball track of the inner ring limit sample under the elastic force of spring B. The movement of steel ball B between the upper limiting plate and the lower limiting plate is free. The contact between steel ball B and the ball track of the inner ring limit sample is completely sufficient. Steel ball B is in contact with the swinging part, and the swinging part has a rotation axis. With a certain rotation, the micrometer probe in contact with the swinging part produces a certain movement, and the pointer reading of the micrometer shows a certain value. Loosen the pull rod, remove the inner ring limit sample, replace it with another ball channel, tighten the pull rod again, and measure until all ball channels are measured once, record the variation range of the micrometer pointer (the difference between the maximum and minimum values), replace the inner ring to be measured, and measure all the ball channels of the inner ring according to the above method. If the micrometer reading variation is within the variation range of the limit sample (within the design requirements), the inner ring ball channels are equally divided and qualified, otherwise they are unqualified and need to be adjusted.

[0006] The advantages of the present invention are: it can quickly and accurately measure the equal division values ​​of the inner ring track, which is not only highly efficient, but also reliable in measuring results, reduces the scrap rate, and liberates the three coordinates; the instrument eliminates potential invisible quality problems and avoids the occurrence of the phenomenon of stopping production waiting for the problem to be solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a structural schematic diagram of a detection device for equally dividing the inner ring track of a transmission shaft according to the present invention.

[0008] Figure 2 yes Figure 1 Top view of the .

[0009] Figure 3 yes Figure 2 Schematic diagram of the AA section in .

[0010] Figure 4 yes Figure 3 Top view of the middle and lower limiting plates.

[0011] Figure 5 yes Figure 2 B view in the figure.

[0012] Figure 6 yes Figure 5 Top view of the swinging part.

[0013] Figure 7 yes Figure 5 Schematic diagram of the rotating shaft.

[0014] Figure 8 It is a schematic diagram of the structure of the inner ring.

[0015] Fig. 9 yes Figure 8 Schematic diagram of the cross section along the CC direction.

[0016] Fig.10 yes Figure 8 A magnified view of the Nakainai Sphere when it is in contact with the steel ball.

[0017] Fig.11 It is a diagram showing the use status of the transmission shaft inner ring track equal division detector of the present invention.

[0018] In the figure: 1 pillar, 2 workbench, 3 positioning boss, 4 expansion sleeve, 5 inner cone, 6 inner hexagonal sink, 7 pull rod, 8 outer cone, 9 threaded rod A, 10 support block, 11 bolt A, 12 bolt B, 13 cylindrical guide hole, 14 steel ball B, 15 upper limiting plate, 16 bracket B, 17 threaded rod C, 18 bolt C, 19 shaft, 20 swing member, 21 probe, 22 gauge rod, 23 bracket D, 24 screw, 25 hole C, 26 micrometer, 27 bracket C, 28 nut C, 29 support block, 30 spring C, 31 bolt E, 32 trisection groove , 33 steel ball A, 34 guide rod A, 35 cylindrical boss A, 36 spring A, 37 hole A, 38 bracket A, 39 nut A, 40 threaded rod B, 41 lower bottom surface, 42 cylindrical boss B, 43 guide rod B, 44 lower limiting plate, 45 bolt D, 46 hole B, 47 nut B, 48 spring B, 49 pin B, 50 upper bottom surface, 51 upper limiting inclined surface, 52 lower limiting inclined surface, 53 pin A, 54 through groove, 55 cylindrical ring, 56 ball track, 57 ball center of ball track, 58 inner hole, 59 cylindrical expansion hole, 60 reference surface, 61 contact point, 62 top clearance. DETAILED DESCRIPTION

[0019] The present invention is a detection instrument for equally dividing the inner ring track of a car constant velocity universal joint transmission shaft. Figure 1-10The embodiment of the present invention is described as follows: the transmission shaft inner ring track equal division detector comprises a pillar 1 and a work table 2, the work table 2 is equipped with a clamping device, an orienting device, a contact device and a measuring device, the work table 2 is fixedly connected to the pillar 1, the work table 2 is provided with a cylindrical guide hole 13, the clamping device comprises an expansion sleeve 4, a pull rod 7, a bolt A11, a support block 10 and a bolt B12, the expansion sleeve 4 is slidably connected with the cylindrical guide hole 13 on the work table 2, the expansion sleeve 4 is provided with a positioning boss 3, the expansion sleeve 4 is provided with an inner conical surface 5, the lower part of the expansion sleeve 4 is provided with a threaded hole, the expansion sleeve 4 is equipped with a pull rod 7, the lower part of the pull rod 7 is provided with a threaded rod portion A9, the threaded rod portion A9 of the pull rod 7 is spirally connected with the threaded hole of the expansion sleeve 4, the pull rod 7 is provided with an outer conical surface 8, the inner conical surface 5 and the outer conical surface 8 are slidably connected, the bolt A11 passes through the work table 2 and is installed on the cylindrical guide The support block 10 in the hole 13 is fixedly connected, and the support block 10 contacts the expansion sleeve 4, which plays a role in adjusting the height position of the expansion sleeve 4. The bolt B12 passes through the hole at the bottom of the workbench 2 and is threadedly connected to the expansion sleeve 4, which is used to position the expansion sleeve 4 and the support block 10 close together; the orientation device includes a bracket A38, a guide rod A34, a nut A39, a steel ball A33, and a spring A36. The bracket A38 is fixedly connected to the workbench 2, and the bracket A38 is provided with a hole A37. The guide rod A34 is slidably connected to the hole A37. A cylindrical boss A35 is provided on the guide rod A34. A threaded rod B40 is provided at the tail end of the guide rod A34. The nut A39 is spirally connected to the threaded rod B40. The front end of the guide rod A34 is fixedly connected to the steel ball A33. The spring A36 is sleeved on the guide rod A34 and is located between the cylindrical boss A35 and the bracket A38;The contact device includes a bracket B16, a bolt C18, an upper limiting plate 15, a pin B49, a bolt D45, a lower limiting plate 44, a pin A53, a steel ball B14, a guide rod B43, a nut B47, and a spring B48. The bracket B16 is fixedly connected to the workbench 2, the bolt C18 passes through the bracket B16 and is fixedly connected to the upper limiting plate 15, the pin B49 is fixedly connected to the bracket B16 and the upper limiting plate 15, the bolt D45 passes through the bracket B16 and is fixedly connected to the lower limiting plate 44, the pin A53 is fixedly connected to the bracket B16 and the lower limiting plate 44, the upper limiting plate 15 and the lower limiting plate 44 have the same structure, and the lower limiting plate 44 has The lower bottom surface 41 and the lower limiting inclined surface 52, the upper limiting plate 15 has an upper bottom surface 50 and an upper limiting inclined surface 51, the steel ball B14 is located between the two opposite upper limiting plates 15 and the lower limiting plate 44, and can slide between the upper and lower limiting plates, the upper limiting inclined surface 51 and the lower limiting inclined surface 52 are used to prevent the steel ball B14 from falling off, the guide rod B43 is supported by the bracket B16, the bracket B16 is provided with a hole B46, the guide rod B43 is slidably connected with the hole B46, the guide rod B43 is provided with a cylindrical boss B42, the cylindrical boss B42 is opposite to the steel ball B14, the steel ball A33 and the steel ball B14 are in the same horizontal plane, and the tail end of the guide rod B43 A threaded rod C17 is provided, the nut B47 is spirally connected to the threaded rod C17, the spring B48 is sleeved on the guide rod B43 and is located between the cylindrical boss B42 and the bracket B16; the measuring device includes a bracket C27, a bracket D23, a rotating shaft 19, a swinging member 20, a cylindrical ring 55, a support block 29, a bolt E31, a nut C28, a spring C30, a micrometer 26, and a screw 24. The bracket C27 and the bracket D23 are respectively fixedly connected to the workbench 2, the rotating shaft 19 is fixedly mounted on the bracket C27, and the swinging member 20 is provided with a cylindrical ring 55, and the swinging member 20 is rotatably connected to the workbench 2 through the cylindrical ring 55. On the rotating shaft 19, a through slot 54 is provided on the swinging member 20, the bracket C27 is fixedly connected with the support block 29, the bolt E31 passes through the through slot 54 on the swinging member 20 and the support block 29 and is spirally connected with the nut C28, the spring C30 is sleeved on the bolt E31 and is located between the support block 29 and the swinging member 20, and its function is to make the swinging member 20 and the steel ball B14 tangentially contact by elastic force, the bracket D23 is equipped with a micrometer 26, the dial gauge rod 22 is located in the hole C25 on the bracket D, the screw 24 on the hole C25 is spirally connected with the bracket D23 and fixes the dial gauge rod 22 to the bracket D23, and the micrometer 26 is provided with a probe 21, and the probe 21 is opposite to the swinging member 20. ;

[0020] The inner ring usually has six or eight ball tracks 56, which are composed of arcs or straight lines + arcs. The inner ring is provided with an inner hole 58 and a reference surface 60. The end of the inner hole 58 is provided with a cylindrical expansion hole 59, and one side is the reference surface 60; the cross-section of the inner ring track 56 is elliptical. When the steel ball A33 or the steel ball B14 contacts the inner ring track 56, there are two contact points 61 with the ellipse. There is a gap between the steel ball and the ellipse of the inner ring track 56, which is usually called a top gap 62. The cross-section of the inner ring track 56 adopts an elliptical shape for the following purposes: first, the steel ball has two contact points 61 with the elliptical inner ring track 56, which is more stable and wear-resistant; second, the top gap 62 between the steel ball and the elliptical inner ring track 56 can facilitate the entry of grease, making the lubrication more sufficient and wear-resistant.

[0021] The working process of the present invention is as follows: first, mark the inner ring whose inner ring track is equally divided after three-coordinate measurement and meets the requirements of the limit sample, and measure the center of the inner ring track as the inner ring limit sample, record the measured value and follow the inner ring limit sample, and adjust the height of the expansion sleeve 4 through bolts A11 and bolts B12 so that the center of the ball track of the inner ring limit sample is on the same horizontal plane as the steel ball A33 and the steel ball B14 (the center value of the ball track of the limit sample + the distance from the positioning boss 3 to the workbench 2 = the distance from the center of the steel ball B14 to the workbench Distance), the inner hole 58 of the inner ring limit sample is mounted on the expansion sleeve 4, so that the reference surface 60 of the inner ring limit sample is close to the positioning boss 3, and the steel ball A33 is in contact with the ball track of the inner ring limit sample under the elastic force of the spring A36, so that the inner ring limit sample is circumferentially positioned, and the pull rod 7 is rotated by the inner hexagonal sink 6 to tighten the inner ring. Under the elastic force of the spring B48, the cylindrical boss B42 pushes the steel ball B14 to contact and close to the adjacent ball track of the inner ring limit sample. Since the steel ball B14 is on the upper bottom surface of the upper limiting plate 15 50 and the lower bottom surface 41 of the lower limit plate 44 are sliding, that is, the steel ball B14 is free when it contacts the inner ring track in the horizontal plane, and the contact between the steel ball B14 and the inner ring limit sample track is completely sufficient. When the steel ball B14 contacts the swing member 20, the swing member 20 rotates around the rotation axis 19 to a certain extent, and the probe 21 of the micrometer 26 in contact with the swing member 20 moves to a certain extent. The pointer reading of the micrometer 26 shows a certain value. Note this value, loosen the pull rod 7, remove the inner ring limit sample, and replace it with the inner ring Another adjacent ballway of the limit sample is positioned circumferentially, and then the pull rod 7 is rotated to tighten the inner ring and measure until all the ballways of the inner ring limit sample are measured, and the variation range (difference between the maximum and minimum values) of the pointer of the micrometer 26 during the measurement of each ballway 56 is recorded. According to the above method, the inner ring to be measured is replaced, and all the ballways 56 of the inner ring are measured. If the reading variation of the micrometer 26 is within the variation range of the limit sample (within the design requirement range), the inner ring ballway is qualified, otherwise it is unqualified and needs to be adjusted. The limit sample is that the difference between the maximum and minimum values ​​of the ballway of the inner ring is the same as the difference between the upper limit value and the lower limit value of the equal division required by the design.

Claims

1. Transmission shaft inner ring track equal division detector, characterized by: The invention comprises a support (1) and a workbench (2), wherein the workbench (2) is fixedly connected to the support (1), a cylindrical guide hole (13) is provided on the workbench (2), a clamping device, an orientation device, a contact device and a measuring device are installed on the workbench (2), the clamping device comprises an expansion sleeve (4), a pull rod (7), a bolt A (11), a support block (10) and a bolt B (12), the expansion sleeve (4) is slidably connected to the cylindrical guide hole (13) on the workbench (2), a positioning boss (3) is provided on the expansion sleeve (4), an inner conical surface (5) is provided in the expansion sleeve (4), a threaded hole is provided at the lower part of the expansion sleeve (4), the pull rod (7) is installed in the expansion sleeve (4), a threaded rod portion A (9) is provided at the lower part of the pull rod (7), and the thread of the pull rod (7) is fixed to the expansion sleeve (4). The threaded rod portion A (9) is spirally connected to the threaded hole of the expansion sleeve (4), the pull rod (7) is provided with an outer conical surface (8), the inner conical surface (5) is slidably connected to the outer conical surface (8), the bolt A (11) passes through the workbench (2) and is fixedly connected to the support block (10) installed in the cylindrical guide hole (13), the support block (10) is in contact with the expansion sleeve (4), the bolt B (12) passes through the workbench (2) and is threadedly connected to the expansion sleeve (4), the orientation device includes a bracket A (38), a guide rod A (34), a nut A (39), a steel ball A (33), and a spring A (36), the bracket A (38) is fixedly connected to the workbench (2), the bracket A (38) is provided with a hole A (37), the guide rod A (34) and the hole A (37) are connected to each other. ) is slidably connected, a cylindrical boss A (35) is provided on the guide rod A (34), a threaded rod B (40) is provided at the rear end of the guide rod A (34), the nut A (39) is spirally connected to the threaded rod B (40), the front end of the guide rod A (34) is fixedly connected to the steel ball A (33), the spring A (36) is sleeved on the guide rod A (34) and is located between the cylindrical boss A (35) and the bracket A (38); the contact device includes a bracket B (16), a bolt C (18), an upper limiting plate (15), a pin B (49), a bolt D (45), a lower limiting plate (44), a pin A (53), a steel ball B (14), a guide rod B (43), a nut B (47), a spring B (48), the bracket B (16) is fixedly connected to the workbench (2), the bolt C (18) passes through the bracket B (16) and is fixedly connected to the upper limiting plate (15), the pin B (49) is fixedly connected to the bracket B (16) and the upper limiting plate (15), the bolt D (45) passes through the bracket B (16) and is fixedly connected to the lower limiting plate (44), the pin A (53) is fixedly connected to the bracket B (16) and the lower limiting plate (44), the upper limiting plate (15) and the lower limiting plate (44) have the same structure, the lower limiting plate (44) has a lower bottom surface (41) and a lower limiting inclined surface (52), the upper limiting plate (15) has an upper bottom surface (50) and an upper limiting inclined surface (51), the steel ball B (14) is located between the upper limiting plate (15) and the lower limiting plate (44), Guide rod B (43) is supported by a bracket B (16), and a hole B (46) is provided on the bracket B (16). Guide rod B (43) is slidably connected with the hole B (46), a cylindrical boss B (42) is provided on the guide rod B (43), the cylindrical boss B (42) is opposite to the steel ball B (14), a threaded rod C (17) is provided at the tail end of the guide rod B (43), the nut B (47) is spirally connected with the threaded rod C (17), the spring B (48) is sleeved on the guide rod B (43) and is located between the cylindrical boss B (42) and the bracket B (16); the measuring device comprises a bracket C (27), a bracket D (23), a rotating shaft (19), a swinging member (20), a cylindrical ring (55), a support block (29), a bolt E (31), a nut C (28), a spring C (30), a micrometer (2 6), screw (24), the bracket C (27) and the bracket D (23) are respectively fixedly connected to the workbench (2), the rotating shaft (19) is fixedly mounted on the bracket C (27), the swing member (20) is provided with a cylindrical ring (55), the swing member (20) is rotatably connected to the rotating shaft (19) through the cylindrical ring (55), the swing member (20) is provided with a through groove (54), the bracket C (27) is fixedly connected to the support block (29), the bolt E (31) passes through the through groove (54) on the swing member (20), and is fixedly connected to the support block (29) through a spiral connection with the nut C (28), the spring C (30) is sleeved on the bolt E (31) and is located between the support block (29) and the swing member (20), Micrometer The dial gauge rod (22) of the micrometer (26) is fastened on the bracket D (23) by a screw (24), and a probe (21) is arranged on the micrometer (26), and the probe (21) is opposite to the swinging member (20).

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