An automatic tolerance adjustment device

Abstract

The present invention provides a tolerance automatic adjustment device, which includes an upper shell, a positioning stud, a locking gasket and an elastic adjusting piece; the upper shell has a hollow cavity structure, and its inner cavity is separated into an installation hole and a first inner cavity by a baffle. The opening end of the installation hole is provided with a protruding outer edge, and positioning ribs are arranged on the outer wall of the upper shell; the elastic adjusting piece is arranged on the outer surface of the positioning rib; the middle part of the positioning stud is provided with a boss matching the first inner cavity, and the boss is inserted into the first inner cavity. The upper shell and the positioning stud are fixed by threaded connection; the locking gasket is arranged in the first inner cavity and moves freely in the axial hole gap formed by the end face of the boss and the baffle of the upper shell. The present invention makes full use of the kinetic energy of bolt rotation and advancement, can automatically eliminate tolerance accumulation, realizes rapid and effective precise positioning and assembly, and solves the defects of multiple processes, high cost, high operation technical difficulty and low work efficiency existing in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of tolerance adjustment devices, and in particular to an automatic tolerance adjustment device. Background Art

[0002] With the rapid development of the automobile industry, the requirements for parts assembly are getting higher and higher. In the process of assembling three or more parts, the accumulation of manufacturing and assembly tolerances leads to the inability to meet the requirements for assembly positioning and final matching. The current solutions are: 1. Reduce manufacturing tolerances, but this will lead to a sharp increase in costs, and it is also impossible to effectively eliminate the accumulated tolerances and achieve the expected positioning and matching; 2. Use adjustment nuts, but manual adjustment is used during the assembly process, which requires extremely high experience and ability of the operating staff, and greatly reduces work efficiency. Summary of the invention

[0003] In view of the defects in the prior art, the purpose of the present invention is to provide an automatic tolerance adjustment device. The present invention fully utilizes the kinetic energy of the rotation and advancement of the bolt, can automatically eliminate tolerance accumulation, and realize fast and effective precise positioning and assembly, thereby solving the defects of the prior art such as many processes, high cost, high operating technical difficulty, and low work efficiency.

[0004] According to one aspect of the present invention, there is provided an automatic tolerance adjustment device, comprising an upper shell (1), a positioning stud (2), a locking washer (3) and an elastic adjustment sheet (4); the upper shell (1) is a hollow cavity structure, and its inner cavity is divided into a mounting hole (14) and a first inner cavity (13) by a baffle (18), the opening end of the mounting hole (14) is provided with a raised outer edge (11), and the outer wall of the upper shell (1) is provided with a positioning rib (12); the elastic adjustment sheet (4) is arranged on the outer surface of the positioning rib (12); the middle part of the positioning stud (2) is provided with a boss (26) matching the first inner cavity (13), the boss (26) is inserted into the first inner cavity (13), and the upper shell (1) and the positioning stud (2) are fixed by threaded connection; the locking washer (3) is arranged in the first inner cavity (13), and moves freely in the shaft hole gap formed by the end face of the boss (26) and the baffle (18) of the upper shell (1). That is, the locking gasket (3) is limited by the end face of the boss (26) and the baffle (18) of the upper shell (1), and moves freely in a plane perpendicular to the axial direction of the positioning stud (2), automatically eliminating the free adjustment of the tolerances in the X and Y directions of the plane where the end face of the positioning stud is located (the plane perpendicular to the positioning stud).

[0005] Preferably, the elastic adjustment sheet (4) is a spring or a spring sheet, which includes an elastic edge (41) and a hole (42), and the elastic edge (41) is provided with a single layer or multiple layers. The elastic adjustment sheet (4) is sleeved on the outer surface of the positioning rib (12) and is constrained by the fixed mechanism and the raised outer edge (11) of the upper shell. The elastic adjustment sheet (4) is compressed by elastic force and moves freely along the axial direction of the upper shell to achieve tolerance adjustment in the coaxial direction with the positioning stud.

[0006] Preferably, the locking washer (3) is made of manganese steel or stainless steel, the positioning stud (2) is made of nylon 6, nylon 66 or POM, and the hardness of the positioning stud (2) is lower than the hardness of the locking washer (3). The locking washer (3) is an elastic steel material, and the material can be a heat-treated manganese steel series steel (65Mn or 60Si2Mn) or stainless steel series steel (SU304) with a certain hardness and elasticity. The positioning stud (2) needs to have rigidity and toughness, so that the radial convex pattern on the locking washer can be embedded in the end face of the boss of the positioning stud, thereby increasing the friction force when the locking washer and the positioning stud are frictionally locked.

[0007] Preferably, the locking washer (3) is provided with an inner hole (31), and the end surface of the locking washer (3) is provided with radial convex patterns (32). The radial convex patterns (32) on the end surface of the locking washer (3) ensure that the locking washer (3) has sufficient friction force at any position of the end surface of the boss (26) of the positioning stud (2) to lock the positioning stud (2) and effectively prevent the locking washer from moving under vibration and gravity. The radial convex patterns of the locking washer have strong friction force with the end surface of the boss of the positioning stud, which can effectively lock the position and solve the problem that the grid pattern and the straight pattern are prone to offset.

[0008] Preferably, a first thread (15) is provided on the inner wall of the first inner cavity (13), and a plurality of thread stop grooves (17) are provided on the outer wall of the opening end of the first inner cavity (13).

[0009] Preferably, a second inner cavity (21) is provided in the boss (26), and a second thread (22) matching with the first thread (15) is provided on the outer wall of the boss (26).

[0010] Preferably, the outer diameter of the locking gasket (3) is smaller than the diameter of the first inner cavity (13), and larger than the diameters of the mounting hole (14) and the second inner cavity (21), and the diameter of the inner hole (31) is smaller than the diameter of the second inner cavity (21).

[0011] Preferably, the height L of the boss (26) is 1 Less than the depth L of the first inner cavity (13) 2 The thickness L of the locking washer (3) is3 The conditions met are: L 3 <(L 2 -L 1 ), so that the locking washer (3) can move freely in a plane perpendicular to the axial direction of the positioning stud (2).

[0012] Preferably, there are multiple positioning ribs (12), all of which are arranged perpendicular to the wall of the upper shell (1); one end of the positioning rib (12) is fitted and connected to the lower surface of the raised outer edge (11), and the other end is provided with a mechanism stop ladder (16).

[0013] Preferably, a stop card (23) and a positioning tension sheet (24) are provided on the wall of the positioning stud (2), and the stop card (23) and the positioning tension sheet (24) are alternately arranged on the outer ring of the boss (26), and a groove (27) for accommodating the wall of the upper shell (1) is provided between the stop card (23) and the boss (26), and a stop groove (25) is provided on the surface of the groove (27). The structure of the stop card (23) and the positioning tension sheet (24) has an elastic effect, and the device can quickly complete the center adjustment and coaxial positioning of the device and the connecting mechanism by using the stop card (23) and the positioning tension sheet (24). The first thread (15) of the upper shell stops at the stop groove (25) of the positioning stud (2), and is doubly locked with the small thread inclination to prevent loosening.

[0014] Preferably, the upper shell (1) and the positioning stud (2) are both integrally formed structures.

[0015] The working principle of the present invention is:

[0016] (1) The elastic compressive deformation of the elastic adjustment sheet is mainly used to eliminate the tolerance accumulation in the Z direction along the axial advancement direction of the bolt during the installation of the fixed mechanism (the existing tolerance adjustment device either does not adjust the Z-direction tolerance, or performs rigid adjustment in a complex and inefficient manner);

[0017] (2) The locking gasket is freely moved in the shaft hole gap to realize the free adjustment of the tolerance in the X and Y directions of the plane perpendicular to the positioning stud; during the installation process, the guiding force when the bolt is rotated into the nut drives the locking gasket to move to the required position in the X and Y directions in the shaft hole gap; and the pressure when the bolt is tightened presses the locking gasket and generates friction to lock the locking gasket at the XY point position of the shaft hole gap, automatically realizing the tolerance adjustment in the X and Y directions of the plane perpendicular to the positioning stud;

[0018] (3) The radial convex pattern on the end face of the locking washer ensures that the locking washer has sufficient friction at any position on the boss end face of the positioning stud to lock the positioning stud and effectively prevent the locking washer from moving under vibration and gravity (grid patterns and straight patterns are prone to offset); that is:

[0019] a) The locking washer can move freely in the X and Y directions. When the bolt is screwed into the nut during installation, the locking washer is driven by the bolt to move to the required X and Y positions;

[0020] b) When the bolt is used to lock the positioning stud, the torque of the bolt compresses the locking washer, and the radial convex pattern has a small area and a strong pressure, which allows the locking washer to lock the positioning stud;

[0021] c) If straight lines are used, when the direction of the straight lines is consistent with the direction of gravity, there is a risk of parts sliding; if grid lines are used, the texture area leads to small pressure and poor locking effect;

[0022] (4) Due to the different hardness of the locking washer and the positioning stud, the radial convex pattern on the locking washer can be embedded in the boss end face of the positioning stud to increase the friction force when the locking washer and the positioning stud are locked. At the same time, the radial pattern can effectively resist the force generated by long-term temperature changes and vibrations, prevent the locking washer and the positioning stud from shifting their positions, and avoid tolerances in the X and Y directions during use.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The automatic tolerance adjustment device of the present invention can quickly complete the center adjustment and coaxial positioning of the device and the connecting mechanism by using the stop card and the positioning tension plate; realize the tolerance adjustment in the Z direction coaxial with the positioning stud by using the elastic floating compression of the elastic adjustment plate; realize the free adjustment of the tolerance in the X and Y directions of the plane perpendicular to the positioning stud by using the locking gasket to move freely in the shaft hole gap, thereby realizing the tolerance adjustment in the three directions of X / Y / Z; and realize the locking position by using the friction between the radial convex pattern of the locking gasket and the end face of the positioning stud boss, so as to realize the locking of the adjustment position after solving the anti-loosening problem;

[0025] (2) The automatic tolerance adjustment device of the present invention fully utilizes the kinetic energy of the bolt's rotation and advancement, and can automatically eliminate the tolerance accumulation in the three directions of X / Y / Z at one time during the bolt tightening process, thereby achieving fast and effective precise positioning and assembly, and solving the defects of the prior art such as multiple processes, high cost, high operating technical difficulty, and low work efficiency (the traditional method can only adjust one tolerance separately or requires multiple processes to adjust the axial tolerance);

[0026] (3) The automatic tolerance adjustment device involved in the present invention mainly uses the elastic positioning principle, friction locking principle and plastic deformation principle to adjust the tolerance of the two dimensions of the plane; and uses the elastic compression principle to adjust the axial tolerance by elastic floating;

[0027] (4) The automatic tolerance adjustment device of the present invention has a wide range of applications and can achieve the purpose of rapid assembly and rapid adjustment in complex and limited installation environments such as automobiles, aviation, home appliances, ships, doors, etc. It also has high positioning strength and precise positioning, greatly improving work efficiency and reducing production costs and quality costs;

[0028] (5) The automatic tolerance adjustment device of the present invention can transfer the tolerance adjustment work in complex spaces to the adjustment work during the parts development and processing process through early project intervention, and can also carry out targeted development of serialized modular products and flexible batch automatic processing to meet the diverse requirements of customers, greatly improve the development speed and reduce the project development cost;

[0029] (6) The tolerance automatic adjustment device involved in the present invention, the radial convex pattern and the soft and hard matching characteristics of the material effectively prevent the displacement caused by temperature difference changes and vibrations, and extend the service life of the device;

[0030] (7) The automatic tolerance adjustment device of the present invention has a simple structure, ingenious design and remarkable effect;

[0031] (8) The automatic tolerance adjustment device involved in the present invention is easy to process and assemble, has high positioning accuracy, low cost, strong practicality, and is suitable for large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0033] Figure 1 It is a schematic diagram of the structure of the upper shell;

[0034] Figure 2 It is a schematic diagram of the structure of the positioning stud;

[0035] Figure 3 It is a structural schematic diagram of a locking gasket;

[0036] Figure 4 is a schematic diagram of the structure of the elastic adjustment sheet;

[0037] Figure 5 It is a connection diagram of the automatic tolerance adjustment device and the connecting mechanism. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0039] Example

[0040] This embodiment provides a tolerance automatic adjustment device, the structure of which is detailed in the attached Figure 1-4 As shown: it includes an upper shell 1, a positioning stud 2, a locking gasket 3 and an elastic adjustment sheet 4; the upper shell 1 is a hollow cavity structure, and its inner cavity is divided into a mounting hole 14 and a first inner cavity 13 by a baffle 18, the open end of the mounting hole 14 is provided with a raised outer edge 11, and a positioning rib 12 is provided on the outer wall of the upper shell 1; the elastic adjustment sheet 4 is arranged on the outer surface of the positioning rib 12; a boss 26 matching the first inner cavity 13 is provided in the middle part of the positioning stud 2, the boss 26 is inserted into the first inner cavity 13, and the upper shell 1 is fixed to the positioning stud 2 by a threaded connection; the locking gasket 3 is arranged in the first inner cavity 13, and moves freely in the axial hole gap formed by the end face of the boss 26 and the baffle 18 of the upper shell 1. That is, the locking gasket 3 is limited by the end face of the boss 26 and the baffle 18 of the upper shell 1, and moves freely in a plane perpendicular to the axial direction of the positioning stud 2, automatically eliminating the free adjustment of the X-direction and Y-direction tolerances of the plane where the end face of the positioning stud is located (the plane perpendicular to the positioning stud).

[0041] Furthermore, the elastic adjustment piece 4 is a spring or a spring sheet, which includes an elastic edge 41 and a hole 42, and the elastic edge 41 is provided with a single layer or multiple layers. The elastic adjustment piece 4 is sleeved on the outer surface of the positioning rib 12 and is constrained by the fixed mechanism and the raised outer edge 11 of the upper shell. The elastic adjustment piece 4 is compressed by elastic force and moves freely along the axial direction of the upper shell to achieve tolerance adjustment in the coaxial direction with the positioning stud.

[0042] Furthermore, the locking washer 3 is made of manganese steel or stainless steel, the positioning stud 2 is made of nylon 6, nylon 66 or POM, and the hardness of the positioning stud 2 is lower than the hardness of the locking washer 3. The locking washer 3 is an elastic steel material, and the material can be a heat-treated manganese steel series steel (65Mn or 60Si2Mn) or stainless steel series steel (SU304) with a certain hardness and elasticity. The positioning stud 2 needs to have rigidity and toughness, so that the radial convex pattern on the locking washer can be embedded in the end face of the boss of the positioning stud, increasing the friction force when the locking washer and the positioning stud are frictionally locked.

[0043] Furthermore, the locking washer 3 is provided with an inner hole 31, and the end surface of the locking washer 3 is provided with a radial convex pattern 32. The radial convex pattern 32 on the end surface of the locking washer 3 enables the locking washer 3 to have sufficient friction at any position of the end surface of the boss 26 of the positioning stud 2 to lock the positioning stud 2 and effectively prevent the locking washer from moving under vibration and gravity. The radial convex pattern of the locking washer has strong friction with the end surface of the positioning stud boss, which can effectively lock the position and solve the problem that the grid pattern and the straight pattern are prone to offset.

[0044] Furthermore, a first thread 15 is provided on the inner wall of the first inner cavity 13 , and a plurality of thread stop grooves 17 are provided on the outer wall of the opening end of the first inner cavity 13 .

[0045] Furthermore, a second inner cavity 21 is provided in the boss 26 , and a second thread 22 matching with the first thread 15 is provided on the outer wall of the boss 26 .

[0046] Furthermore, the outer diameter of the locking washer 3 is smaller than the diameter of the first inner cavity 13 , and larger than the diameters of the mounting hole 14 and the second inner cavity 21 , and the diameter of the inner hole 31 is smaller than the diameter of the second inner cavity 21 .

[0047] Furthermore, the height L of the boss 26 is 1 Less than the depth L of the first inner cavity 13 2 , the thickness L of the locking gasket 3 3 The conditions met are: L 3 <(L 2 -L 1 ), so that the locking washer 3 can move freely in a plane perpendicular to the axial direction of the positioning stud 2.

[0048] Furthermore, there are multiple positioning ribs 12, and all are vertically arranged with the wall of the upper shell 1, one end of the positioning rib 12 is fitted and connected with the lower surface of the raised outer edge 11, and the other end is provided with a mechanism stop step 16.

[0049] Furthermore, a stop card 23 and a positioning tension sheet 24 are provided on the wall of the positioning stud 2. The stop card 23 and the positioning tension sheet 24 are alternately arranged on the outer ring of the boss 26, and a groove 27 for accommodating the wall of the upper shell 1 is provided between the boss 26, and a stop groove 25 is provided on the surface of the groove 27. The structure of the stop card 23 and the positioning tension sheet 24 has an elastic effect. The device can quickly complete the center adjustment and coaxial positioning of the device and the connecting mechanism by using the stop card 23 and the positioning tension sheet 24. The first thread 15 of the upper shell stops at the stop groove 25 of the positioning stud 2, and is doubly locked with the small thread inclination to prevent loosening.

[0050] Furthermore, the upper shell 1 and the positioning studs 2 are both integrally formed structures.

[0051] The installation and adjustment process of the automatic tolerance adjustment device and the fixed mechanism is as follows (such as the installation of a car door handle). The structure is detailed in the attached Figure 5 As shown:

[0052] Step 1: The positioning stud 2 in the automatic tolerance adjustment device passes through the first mounting hole 51 of the first fixed mechanism 5 (door handle), the stop card 23 is buckled in the first mounting hole 51, and pops up to limit the first fixed mechanism 5 from retreating, the first mounting hole 51 of the first fixed mechanism 5 is limited between the elastic edge 41 of the elastic adjustment sheet 4 and the stop card 23, and at the same time, the positioning tensioning sheet 24 of the positioning stud 2 is tightened for coaxial positioning;

[0053] Step 2: The mounting matching device 52 of the first fixed mechanism 5 is pushed into and pre-positioned in the second mounting hole of the second fixed mechanism 7 (door outer sheet metal), and then the bolt 6 is sequentially passed through the mounting hole 14 of the upper shell 1, the inner hole 31 of the locking washer 3, the second inner cavity 21 of the positioning stud 2, and the third mounting hole 81 of the third fixed mechanism 8 (door inner sheet metal), and connected and locked with the mounting nut 9. An elastic body 54 is provided at the connection between the first fixed mechanism 5 and the second fixed mechanism 7. The elastic body 54 is elastic foam, sealant, or other elastic objects, and its function is sealing and shock absorption, wherein:

[0054] 1) The elastic body 54 and the elastic adjustment sheet 4 are mutually supported by force. The thickness of the elastic body 54 decreases with the increase of pressure, and increases with the decrease of pressure. The total source of force comes from the axial distance of the bolt 6. When the axial distance is large, the compression of the elastic adjustment sheet 4 is small, the elastic force is small, and the thickness of the elastic body 54 is large; when the axial distance is small, the compression of the elastic adjustment sheet 4 is large, the elastic force is large, and the thickness of the elastic body 54 is small, thereby achieving the tolerance adjustment in the axial Z direction. The two elastic bodies (elastic adjustment sheet 4 and elastic body 54) can well achieve dynamic balance, adjust force, reduce shock and prevent noise, and the effect is optimal.

[0055] 2) If the elastic body 54 is replaced with a rigid object, its function is only to seal, and the tolerance adjustment in the axial Z direction is entirely borne by the deformation of the elastic adjustment sheet 4 to achieve the tolerance adjustment in the axial Z direction. When there is only one elastic body (elastic adjustment sheet 4), although the elastic adjustment sheet 4 adjusts the tolerance, it is not as good as the solution with two elastic bodies in terms of vibration reduction and noise prevention.

[0056] 3) Whether the elastomer 54 is an elastomer depends on the actual application and is not within the functional scope of this product.

[0057] During the locking process, the locking gasket 3 can move freely in the axial hole gap formed by the end face of the boss 26 of the positioning stud 2 and the baffle 18 of the upper shell 1, automatically eliminating the two axial tolerances of the plane where the end face of the positioning stud 2 is located (the X direction and the Y direction of the plane perpendicular to the positioning stud, that is, the front and back left and right directions of the axial hole gap), until the radial convex pattern 32 of the locking gasket 3 presses the end face of the boss 26 of the positioning stud 2, and the friction force limits the locking gasket 3 on the end face of the boss 26 of the positioning stud 2. The distance between the stop card 23 of the positioning stud 2 and the lower end face of the positioning stud 2 is preset to be less than the theoretical distance for installing the first fixed mechanism 5 under no force. During the process of locking the bolt 6, the elastic edge 41 of the elastic adjustment sheet 4 presses the first fixed mechanism 5 to automatically position and closely cooperate with the second fixed mechanism 7, completing the cumulative elimination of tolerances in the coaxial direction with the positioning stud (axial Z direction, that is, the up and down direction along the axial direction of the positioning stud). Thus, the cumulative elimination of tolerances in three directions is finally achieved.

[0058] When the first fixed mechanism 5 is forced to compress the elastic adjustment piece 4 and retreat, the mechanism stop step 16 in the upper shell 1 clamps the edge 53 of the first fixed mechanism 5, restricting the first fixed mechanism 5 within a reasonable working range, ensuring that the elastic adjustment piece 4 works within a safe compression range, and ensuring the safe operation of the first fixed mechanism 5.

[0059] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. An automatic tolerance adjustment device, characterized in that, It includes an upper shell (1), a positioning stud (2), a locking gasket (3) and an elastic adjusting piece (4); the upper shell (1) has a hollow cavity structure, and its inner cavity is divided into a mounting hole (14) and a first inner cavity (13) by a baffle (18). A raised outer edge (11) is provided at the open end of the mounting hole (14), and a positioning rib (12) is provided on the outer wall of the upper shell (1); the elastic adjusting piece (4) is arranged on the outer surface of the positioning rib (12); a boss (26) matching the first inner cavity (13) is provided in the middle of the positioning stud (2), the boss (26) is inserted into the first inner cavity (13), and the upper shell (1) and the positioning stud (2) are fixed by threaded connection; the locking gasket (3) is arranged in the first inner cavity (13) and moves freely in the axial hole gap formed by the end face of the boss (26) and the baffle (18) of the upper shell (1); the locking gasket (3) is provided with an inner hole (31), wherein the height L of the boss (26) 1 is less than the depth L of the first inner cavity (13) 2 , and the thickness L of the locking gasket (3) 3 satisfies the condition: L 3 < (L 2 - L 1 ).

2. The automatic tolerance adjustment device according to claim 1, characterized in that, The elastic adjusting piece (4) is a spring or a spring piece, which includes an elastic edge (41) and an intermediate hole (42), and the elastic edge (41) is provided with one layer or multiple layers.

3. The automatic tolerance adjustment device according to claim 1, characterized in that, The locking gasket (3) is made of manganese steel type steel or stainless steel type steel, the positioning stud (2) is made of nylon 6, nylon 66 or POM, and the hardness of the positioning stud (2) is lower than that of the locking gasket (3).

4. The automatic tolerance adjustment device according to claim 1, characterized in that, The end face of the locking gasket (3) is provided with radial convex lines (32).

5. The automatic tolerance adjustment device according to claim 4, characterized in that, The inner wall of the first inner cavity (13) is provided with a first thread (15), and the outer wall of the open end of the first inner cavity (13) is provided with a plurality of thread stop grooves (17).

6. The automatic tolerance adjustment device according to claim 5, characterized in that, A second inner cavity (21) is provided in the boss (26), and a second thread (22) matching the first thread (15) is provided on the outer wall of the boss (26).

7. The automatic tolerance adjustment device according to claim 6, characterized in that, The outer diameter of the locking gasket (3) is smaller than the diameter of the first inner cavity (13), and larger than the diameters of the mounting hole (14) and the second inner cavity (21), and the diameter of the inner hole (31) is smaller than the diameter of the second inner cavity (21).

8. The automatic tolerance adjustment device according to claim 1, characterized in that, A plurality of positioning ribs (12) are provided, and they are all perpendicular to the wall of the upper shell (1). One end of the positioning rib (12) is attached to the lower surface of the outer edge of the protrusion (11), and the other end is provided with a mechanism stop step (16).

9. The automatic tolerance adjustment device according to claim 1, characterized in that, A stop card (23) and a positioning tensioning piece (24) are provided on the wall of the positioning stud (2). The stop card (23) and the positioning tensioning piece (24) are alternately arranged on the outer ring of the boss (26), and there is a groove (27) for accommodating the wall of the upper shell (1) between them. The surface of the groove (27) is provided with a stop groove (25).

Images