Self-centering assembly fixture

Abstract

The utility model discloses a self-centering assembly fixture which comprises a positioning seat and a self-centering mechanism, wherein the positioning seat is provided with a target piece placing hole with a waist-shaped cross section; at least one part of the self-centering mechanism is arranged in the positioning seat, the self-centering mechanism comprises four pinnacle centering driven pieces and a disc cam used for driving the four pinnacle centering driven pieces to reciprocate along the axis at the same time, the outer contour of the disc cam is provided with four identical straight edges, and the distance from the midpoint of each straight edge to the center of the disc cam is minimum. And the tip ends of the four pinnacle centering followers are always attached to the outer contour of the disc cam. On the basis of reducing cost and canceling a keyway machining procedure, the concentricity after assembly is ensured to meet the technical requirement, the problem that a clamp is blocked after assembly in the prior art is solved, the assembly difficulty is low, the operation is simple and convenient, and the fatigue feeling of staff in use can be reduced.

Description

Technical Field

[0001] The utility model belongs to the field of tooling fixtures, and in particular relates to a self-centering assembly fixture. Background Art

[0002] A fixture is a part used to fix the object to be processed during the mechanical manufacturing process so that it has the correct position to be processed or inspected.

[0003] During the assembly process of the coupling in the air compressor product, a flat key connection is required to ensure that the concentricity is within the requirement of 0.28mm. Flat key connection is usually used to ensure concentricity. Canceling the flat key connection can effectively save product costs and improve production efficiency, but the existing fixture cannot ensure that the concentricity meets the requirements on the basis of canceling the flat key connection, and the fixture is easily blocked after assembly and cannot be taken out. Utility Model Content

[0004] In order to solve the deficiencies of the prior art, the utility model provides a self-centering assembly fixture, comprising:

[0005] A positioning seat having a target piece placement hole with a waist-shaped cross section;

[0006] The self-centering mechanism, at least a part of which is arranged inside the positioning seat, includes four pointed top centering followers and a disc cam for simultaneously driving the four pointed top centering followers to reciprocate along the axis, the outer contour of the disc cam has four identical straight edges and the distance from the midpoint of each straight edge to the center of the disc cam is the smallest, and the tips of the four pointed top centering followers always fit the outer contour of the disc cam;

[0007] wherein the axis comprises a first axis and a second axis which are arranged perpendicularly to each other, two of the four pointed-top centering followers are symmetrically arranged along the first axis and the remaining two pointed-top centering followers are symmetrically arranged along the second axis; and

[0008] When the self-centering assembly fixture is in a relaxed state, the tips of the four pointed centering followers are respectively in contact with the midpoints of the corresponding straight sides of the disc cam.

[0009] In some embodiments, the positioning seat includes:

[0010] The seat body has a central portion with a protruding shaft hole and a boss hole extending vertically therethrough and a side wall portion with four slide grooves arranged circumferentially therefrom; and

[0011] A placement portion having an annular structure and fixedly connected to the top surface of the seat body portion, an inner area of ​​the placement portion constituting a target piece placement hole of the positioning seat and a side wall thereof having threaded holes and screws connected through the threaded holes, the number of the threaded holes being not less than four and the number of the screws being not less than two;

[0012] Among them, the target part placement hole of the placement part is vertically connected with the protruding shaft hole and the boss hole of the seat body part, the seat body part and the placement part have the same central axis, and the central axis is perpendicular to the plane formed by the first axis and the second axis.

[0013] In some embodiments, the seat body portion comprises:

[0014] The first plate portion has four identical straight side walls and four identical arc side walls, the four straight side walls and the four arc side walls are alternately connected to form an annular side wall, the center of the first plate portion has a protruding shaft hole penetrating from the top surface to the bottom surface, and the center of each straight side wall has a sliding groove that forms a reciprocating sliding structure with a corresponding pointed top centering follower; and

[0015] The second plate portion is located on the bottom surface of the first plate portion and has a boss hole at its center that passes through from the top surface to the bottom surface.

[0016] The first plate portion and the second plate portion are detachable and both the first plate portion and the second plate portion are provided with four arc-shaped holes penetrating the top surface and the bottom surface of the seat main body portion.

[0017] In some embodiments, the disc cam further comprises:

[0018] A protruding shaft is arranged at the center of the top surface of the disc cam, and the top end of the protruding shaft passes through the protruding shaft hole of the positioning seat and is connected to the positioning seat; and

[0019] Four identical arc edges, which are alternately connected with the straight edges of the disc cam to form the outer contour of the disc cam;

[0020] The disc cam is confined inside the positioning seat and its bottom surface contacts the upper end surface of the second plate portion. The transition between the arc edge and the straight edge of the disc cam is a rounded corner, and the distance from any point on the arc edge to the center of the disc cam is the maximum distance.

[0021] In some embodiments, each of the apex centering followers further comprises:

[0022] The pointed top moving block has a movable hole that penetrates the top surface and the bottom surface of the pointed top moving block, the cross section of the movable hole is rectangular, the tip of the pointed top moving block has a rounded corner and the outer end opposite to the tip has an arc surface with the same inner diameter as the assembled product, and the remaining side ends of the pointed top moving block are chamfered ends;

[0023] A vertical fixing seat, the top end of which is fixedly connected to the top surface of the positioning seat and the bottom end of which is arranged in the movable hole of the pointed top moving block;

[0024] A guide cross bar is arranged in the movable hole of the pointed top moving block along the corresponding axial direction, one end of the guide cross bar is fixedly connected to the bottom end of the vertical fixing seat and the other end thereof is at a distance from the inner wall corresponding to the movable hole in the pointed top moving block; and

[0025] A spring is sleeved on the guide crossbar, one end of the spring is connected to the inner wall of the movable hole in the pointed moving block and the other end of the spring is connected to the bottom end of the vertical fixed seat;

[0026] Among them, when the self-centering assembly fixture is in a relaxed state, the compression of the spring is zero; when the self-centering assembly fixture is in a clamped state, the compression of the spring is the largest.

[0027] In some embodiments, the positioning seat further includes an internal hole of the positioning seat for limiting the moving direction of the pointed top moving block in the self-centering mechanism.

[0028] In some embodiments, the self-centering assembly fixture includes two anti-rotation fixing parts symmetrically arranged along the first axis or the second axis.

[0029] In some embodiments, the anti-rotation fixing portion includes:

[0030] A transverse fixing seat, one end of which is fixedly arranged on the bottom edge of the positioning seat and the other end of which has a groove penetrating the side of the transverse fixing seat;

[0031] a connecting member, one end of which is embedded in the groove wall portion of the transverse fixing seat and the other end of which is located outside the transverse fixing seat; and

[0032] The anti-rotation unit has one part arranged in the groove of the transverse fixing seat and connected by a connecting piece and the other part located outside the transverse fixing seat. The outer part of the transverse fixing seat is provided with an anti-rotation pad whose surface is close to the outer wall corresponding to the positioning seat.

[0033] In some embodiments, the self-centering assembly fixture includes a handle whose length extends along the central axis direction, and the top boss of the handle passes through the boss hole in the positioning seat and is fixedly connected to the bottom center of the disc cam in the self-centering mechanism, and its bottom is fixedly connected to the handle seat, and the bottom of the handle seat has a hexagonal groove.

[0034] In some embodiments, the self-centering fixture includes at least one anti-rotation pin, and the second plate portion in the positioning seat also has at least one round waist-shaped track groove extending from the top surface to the bottom surface, and the anti-rotation pin passes through the round waist-shaped track groove corresponding to the second plate portion in the positioning seat and is fixedly connected to the disc cam;

[0035] Wherein, when the self-centering fixture is in a relaxed state, the anti-rotation pin is located at one end of the round waist-shaped track groove;

[0036] When the self-centering clamp is in a clamped state, the stop pin is located at the other end of the round waist-shaped track groove; both ends of the round waist-shaped track groove are marked with markings indicating the loose state and clamped state of the self-centering clamp.

[0037] The beneficial effects of the utility model are as follows: using the utility model can ensure that the concentricity is within the requirement of 0.28mm while eliminating the flat key connection during the assembly process of the coupling in the air compressor product, and the employees can easily remove the fixture after assembly without being suffocated. The utility model has a compact structure and low weight, can reduce the fatigue of employees during use, has low assembly difficulty, and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0039] Figure 1 It is a three-dimensional schematic diagram of a self-centering assembly fixture provided in one embodiment of the utility model.

[0040] Figure 2 It is a vertical cross-sectional view of a self-centering assembly fixture provided in one embodiment of the utility model.

[0041] Figure 3 It is a schematic plan cross-sectional view of a self-centering assembly fixture provided in one embodiment of the utility model.

[0042] Figure 4 The utility model is provided in one embodiment of the self-centering assembly fixture bottom surface structure schematic diagram.

[0043] Figure 5 It is a schematic diagram of the working state of the self-centering assembly fixture provided in one embodiment of the utility model.

[0044] Figure 6 It is a cross-sectional view of the working state of the self-centering assembly fixture provided in one embodiment of the utility model. DETAILED DESCRIPTION

[0045] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0046] like Figure 1 and Figure 2 As shown, in one embodiment, the self-centering assembly fixture includes: a positioning seat 10 and a self-centering mechanism 20.

[0047] The positioning seat 10 has a target part placement hole 103, and the cross section of the target part placement hole 103 is waist-shaped. The target part placement hole 103 of the positioning seat 10 is used to place the target part. In one embodiment, the target part includes a coupling.

[0048] like Figure 1 and Figure 2 As shown, in one embodiment, the positioning seat 10 includes a seat body portion 101 and a placement portion 102. The middle portion of the seat body portion 101 has a vertically penetrating protruding shaft hole 1011 and a boss hole 1012, and the side wall portion has four slide grooves 1013 that are arranged together in a circumferential direction. The protruding shaft hole 1011 and the boss hole 1012 of the seat body portion 101 are used to install the protruding shaft 202c of the disc cam 202 and the top boss of the handle 60, respectively. Each slide groove 1013 of the seat body portion 101 and each pointed top centering follower 201 constitute a reciprocating sliding structure; the placement portion 102 has an annular structure and is fixedly connected to the top surface of the seat body portion 101. The inner area of ​​the placement portion 102 constitutes the target part placement hole 103 of the positioning seat 10 and its side wall has a threaded hole 1021 and a screw 1022 connected through the threaded hole. The number of the threaded holes 1021 is not less than four and the number of the screws 1022 is not less than two. As shown Figure 2 As shown, in one embodiment, the screw 1022 is a hexagon socket head screw.

[0049] Among them, the target part placement hole 103 of the placement part 102 is vertically connected with the protruding shaft hole 1011 and the boss hole 1012 of the seat main body part 101; the seat main body part 101 and the placement part 102 have the same central axis 40, and the central axis 40 is perpendicular to the plane formed by the first axis 30a and the second axis 30b.

[0050] like Figure 1-Figure 3 As shown, in one embodiment, the seat body part 101 includes a first plate part 1014 and a second plate part 1015, and the first plate part 1014 and the second plate part 1015 are detachable. The first plate part 1014 has four identical straight side walls 1014a and four identical arc side walls 1014b, and the four straight side walls 1014a and the four arc side walls 1014b are alternately connected to form an annular side wall; the center of the first plate part 1014 has a protruding shaft hole 1011 that passes through from the top surface to the bottom surface; the center of each straight side wall 1014a of the first plate part 1014 has a slide groove 1013 for each pointed centering follower 201 to slide back and forth; the first plate part 1014 and the second plate part 1015 are connected to each other by a plurality of channels 1014a and 1015 ... The second plate 1015 has four arc holes 1016 that penetrate the top and bottom surfaces of the seat body 101, and the overlapping positions have the effect of reducing weight and facilitating observation. Each arc hole 1016 is located between the outer periphery of the placement part 102 and the outer periphery of the first plate 1014 and is aligned with the corresponding arc side wall 1014b of the first plate 1014; the second plate 1015 is located on the bottom surface of the first plate 1014 and has a boss hole 1012 that penetrates from the top to the bottom surface at its center. Figure 4As shown, in one embodiment, the second plate portion 1015 has at least one rounded track groove 1017 penetrating from the top surface to the bottom surface.

[0051] like Figure 2 As shown, in one embodiment, in order to ensure that the pointed top centering follower 201 of the self-centering mechanism 20 moves along the axis, the positioning seat 10 also includes an internal hole 104 of the positioning seat that limits the movement direction of the pointed top moving block 2011 in the self-centering mechanism 20.

[0052] At least a part of the self-centering mechanism 20 is arranged inside the positioning seat 10, and the self-centering mechanism 20 includes four pointed top centering followers 201 and a disc cam 202 for simultaneously driving the four pointed top centering followers 201 to reciprocate along the axis 30. The outer contour of the disc cam 202 has four identical straight edges 202a, and the distance from the midpoint of each straight edge 202a to the center of the disc cam 202 is the smallest (that is, this distance is the base circle radius of the disc cam 202), and the tips 2011b of the four pointed top centering followers 201 always fit the outer contour of the disc cam 202;

[0053] Wherein, the axis 30 includes a first axis 30a and a second axis 30b which are arranged perpendicularly to each other, two of the four pointed-top centering followers 201 are symmetrically arranged along the first axis 30a and the remaining two pointed-top centering followers 201 are symmetrically arranged along the second axis 30b; when the self-centering assembly fixture is in a relaxed state, the tips 2011b of the four pointed-top centering followers 201 respectively contact the midpoints of the corresponding straight edges 202a of the disc cam 202.

[0054] like Figure 1-Figure 3 As shown, in one embodiment, the center of the top surface of the disc cam 202 has a protruding shaft 202c, and the top end of the protruding shaft 202c of the disc cam 202 passes through the protruding shaft hole 1011 of the first plate portion 1014 and is connected to the first plate portion 1014; the disc cam 202 is defined inside the positioning seat 10 and its bottom surface is in contact with the upper end surface of the second plate portion 1015; the outer contour of the disc cam 202 also has four identical arc edges 202b, and the straight edges 202a and arc edges 202b of the disc cam 202 are alternately connected to form the outer contour of the disc cam 202;

[0055] The transition between the straight edge 202a and the arc edge 202b of the disc cam 202 is a rounded corner, and the distance from any point on the arc edge 202b to the center of the disc cam 202 is the maximum distance.

[0056] like Figure 2-Figure 3 As shown, in one embodiment, each of the top centering follower 201 includes a top moving block 2011 , a vertical fixing seat 2012 , a guide cross bar 2013 and a spring 2014 .

[0057] The pointed top moving block 2011 has a movable hole 2011a that penetrates the top surface and the bottom surface of the pointed top moving block 2011. In one embodiment, the cross section of the movable hole 2011a of the pointed top moving block 2011 is rectangular. In one embodiment, in order to make the self-centering mechanism 20 more accurately centered, the tip 2011b of the pointed moving block 2011 has rounded corners, thereby reducing the contact area between the pointed moving block 2011 and the outer contour of the disc cam 202 in the self-centering mechanism 20 and reducing useless work; the outer end 2011c of the pointed moving block 2011 opposite to the tip 2011b has an arc surface with the same inner diameter as the assembled product (for example, an air compressor), thereby increasing the contact area between the pointed moving block 2011 and the inner diameter of the product and improving friction; the remaining side ends 2011d on the pointed moving block 2011 are chamfered ends, that is, the pointed moving block 2011 has an angle at the cross section of the chamfered end, thereby better preventing the pointed moving block 2011 from deviating from the direction when making reciprocating motion along the corresponding axis 30.

[0058] The top end of the vertical fixing seat 2012 is fixedly connected to the top surface of the first plate portion 1014 in the positioning seat 10 and the bottom end thereof is disposed in the movable hole 2011 a of the pointed top moving block 2011 .

[0059] The guide cross bar 2013 is arranged in the movable hole 2011a of the pointed top moving block 2011 along the corresponding axis 30 direction, one end of the guide cross bar 2013 is fixedly connected to the bottom end of the vertical fixing seat 2012 and the other end thereof has a distance from the inner wall corresponding to the movable hole 2011a of the pointed top moving block 2011.

[0060] The spring 2014 is sleeved on the guide cross bar 2013, one end of the spring 2014 is connected to the inner wall of the movable hole 2011a in the pointed moving block 2011 and the other end is connected to the bottom end of the vertical fixing seat 2012; in another embodiment, because the other end of the guide cross bar 2013 has a radial protrusion, the other end of the spring 2014 is connected to the radial protrusion;

[0061] Among them, when the self-centering assembly fixture is in a relaxed state, the compression amount of the spring 2014 is zero; when the self-centering assembly fixture is in a clamped state, the compression amount of the spring 2014 is maximum.

[0062] Specifically, when the self-centering assembly fixture begins to clamp, the disc cam 202 rotates around the protruding shaft 202c. Because the tip 2011b of the pointed top moving block 2011 always fits the outer contour of the disc cam 202, when the disc cam 202 rotates, the distance from the contact point between the tip 2011b of the pointed top moving block 2011 and the outer contour of the disc cam 202 and the midpoint of the disc cam 202 becomes larger. Therefore, when the disc cam 202 rotates, it also drives the four pointed top moving blocks 2011 to fit and move outward along the corresponding axis. The spring 2014 in the movable hole 2011a of the pointed top moving block 2011 begins to be compressed by the moving pointed top moving block 2011; the self-centering assembly fixture When the tool is in a clamped state, the pointed moving block 2011 passes through the slide groove 1013 of the first plate portion 1014 and the outer end 2011c of the pointed moving block 2011 contacts the inner wall of the assembled product, and the compression of the spring 2014 is the largest. At this time, the difference between the distance from the contact point between the tip 2011b of the pointed moving block 2011 and the outer contour of the disc cam 202 to the center of the disc cam 202 and the base circle radius is the moving distance of the pointed moving block 2011; when the self-centering assembly returns to a relaxed state, the disc cam 202 returns to its initial position, the spring 2014 returns to a relaxed state, and the rebound force of the spring 2014 drives the pointed moving block 2011 to return to its initial position.

[0063] like Figure 1-Figure 2 As shown, in one embodiment, in order to fix the position of the assembled product to prevent rotation, the self-centering assembly fixture further includes two anti-rotation fixing parts 50 symmetrically arranged along the first axis 30a or the second axis 30b.

[0064] In one embodiment, the anti-rotation fixing part 50 includes a transverse fixing seat 501, a connecting member 502 and an anti-rotation unit 503. One end of the transverse fixing seat 501 is fixedly arranged on the bottom edge of the positioning seat 10 by threaded connection, and the other end thereof has a groove 5011 that penetrates the side of the transverse fixing seat 501; one end of the connecting member 502 is embedded in the groove wall part of the transverse fixing seat 501 and the other end is located outside the transverse fixing seat 501. In one embodiment, the connecting member 502 is a screw; a part of the anti-rotation unit 503 is arranged in the groove 5011 of the transverse fixing seat 501 and connected by the connecting member 502, and a part thereof is located outside the transverse fixing seat 501, and an anti-rotation pad 5031 is arranged on the outside portion, and the surface of the anti-rotation pad 5031 is close to the corresponding outer wall of the positioning seat 10.

[0065] Specifically, the anti-rotation unit 503 rotates around the connecting piece 502 so that one end thereof provided with the anti-rotation pad 5031 is located on both sides of the outer box of the assembled product, and the two anti-rotation pads 5031 are squeezed with the outer box of the product, so that the anti-rotation unit 503 clamps the outer box of the assembled product and maintains a stable position.

[0066] like Figure 1-Figure 2 As shown, in one embodiment, in order to use the clamp more simply and conveniently, the clamp also includes a handle 60 whose length extends along the direction of the central axis 40, and the top boss of the handle 60 passes through the boss hole 1012 of the second plate portion 1015 in the positioning seat 10 and is fixedly connected to the bottom center of the disc cam 202 in the self-centering mechanism 20, and the bottom is fixedly connected to the handle seat 601 by a threaded connection, and the bottom of the handle seat 601 has a hexagonal groove.

[0067] Specifically, the staff holds the handle 60 and pushes the self-centering fixture into the box of the assembled product, inserts a hexagonal wrench or a pneumatic wrench into the hexagonal groove of the handle seat 601 to drive the handle 60 to rotate, thereby driving the disc cam 202 to rotate around the protruding shaft 202c.

[0068] like Figure 4 As shown, in one embodiment, in order to allow the staff to easily identify the working state of the assembly fixture, the self-centering fixture further includes at least one stop pin 70, each stop pin 70 passes through the round waist-shaped track groove 1017 corresponding to the second plate portion 1015 in the positioning seat 10 and is fixedly connected to the disc cam 202. When the self-centering fixture is in a relaxed state, the stop pin 70 is located at one end of the round waist-shaped track groove 1017; when the self-centering fixture is in a clamped state, the stop pin 70 is located at the other end of the round waist-shaped track groove 1017; both ends of the round waist-shaped track groove 1017 are marked with marks indicating the relaxed state and clamped state of the fixture.

[0069] Specifically, Figure 5 and Figure 6As shown, in an embodiment suitable for the assembly of air compressor couplings, the front end of the housing positioning shaft of the air compressor is a large chamfer, so that the clamp can be better guided and centered when it is placed. During operation, the coupling is manually placed in the placement part 102, and the handle 60 is held to push the self-centering clamp and the coupling as a whole into the housing. The anti-rotation unit 503 is rotated to clamp the self-centering clamp to the housing. A hexagonal wrench or pneumatic wrench is inserted into the hexagonal groove of the handle seat 601 to drive the handle 60 to rotate, thereby driving the disc cam 202 to rotate around the protruding shaft 202c. The self-centering assembly clamp is in a clamped state, the pointed moving block 2011 passes through the slide groove 1013 of the first plate portion 1014 and the outer end 2011c of the pointed moving block 2011 contacts the inner wall of the assembled product, the compression amount of the spring 2014 is the largest, and the disc cam 202 drives the stop pin to rotate. The stop pin is located on the round waist-shaped track on the second plate portion 1015 in the positioning seat 10. The end of the groove 1017 is marked with the clamping mark. At this time, the coupling, the fixture, and the box body become a whole. After the staff confirms the clamping through the stop pin, they insert the bolt from the back of the box body to tighten the coupling and the crankshaft, and then insert the hexagonal wrench or pneumatic wrench into the hexagonal groove of the handle seat 601 and rotate it in the opposite direction, so that the handle 60 and the disc cam 202 also rotate in the opposite direction, and the pointed moving block 2011 returns to the initial position under the action of the rebound force of the spring 2014. The self-centering assembly fixture returns to the relaxed state, and the stop pin 70 also returns to the end of the round waist-shaped trajectory groove 1017 on the second plate portion 1015 of the positioning seat 10 marked with the relaxation mark, and the anti-rotation unit 503 is rotated in the opposite direction again, and the handle 60 is held to take out the self-centering assembly fixture.

[0070] The above description is merely a preferred embodiment of one or more embodiments of the present specification and is not intended to limit one or more embodiments of the present specification. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of the present specification shall be included in the scope of protection of one or more embodiments of the present specification.

Claims

1. A self-centering assembly fixture, characterized in that: include: A positioning seat having a target piece placement hole with a waist-shaped cross section; The self-centering mechanism, at least a part of which is arranged inside the positioning seat, comprises four pointed top centering followers and a disc cam for simultaneously driving the four pointed top centering followers to reciprocate along the axis, the outer contour of the disc cam has four identical straight edges and the distance from the midpoint of each straight edge to the center of the disc cam is the smallest, and the tips of the four pointed top centering followers always fit the outer contour of the disc cam; The axis includes a first axis and a second axis that are arranged perpendicularly to each other, two of the four pointed-top centering followers are symmetrically arranged along the first axis and the remaining two pointed-top centering followers are symmetrically arranged along the second axis; as well as When the self-centering assembly fixture is in a relaxed state, the tips of the four pointed-top centering followers are in contact with the midpoints of the corresponding straight edges of the disc-shaped cam respectively.

2. The self-centering assembly fixture according to claim 1, characterized in that: The positioning seat comprises: The seat body has a central portion with a protruding shaft hole and a boss hole extending vertically therethrough and a side wall portion with four slide grooves arranged circumferentially therefrom; and A placement portion having an annular structure and fixedly connected to the top surface of the seat body portion, wherein the inner area of ​​the placement portion constitutes a target piece placement hole of the positioning seat and the side wall thereof has threaded holes and screws connected through the threaded holes, wherein the number of the threaded holes is not less than four and the number of the screws is not less than two; Among them, the target part placement hole of the placement part is vertically connected with the protruding shaft hole and the boss hole of the seat body part, and the seat body part and the placement part have the same central axis, which is perpendicular to the plane formed by the first axis and the second axis.

3. The self-centering assembly fixture according to claim 2, characterized in that: The seat body part comprises: The first plate portion has four identical straight-edge side walls and four identical arc-edge side walls, the four straight-edge side walls are alternately connected with the four arc-edge side walls to form an annular side wall, the center of the first plate portion has a protruding shaft hole penetrating from the top surface to the bottom surface, and the center of each straight-edge side wall has a sliding groove that forms a reciprocating sliding structure with the corresponding pointed centering follower; and A second plate portion, located on the bottom surface of the first plate portion and having a boss hole extending from the top surface to the bottom surface at the center thereof; The first plate portion and the second plate portion are detachable and both the first plate portion and the second plate portion have four arc-shaped holes penetrating the top surface and the bottom surface of the seat body portion.

4. The self-centering assembly fixture according to claim 3, characterized in that: The disc cam also includes: A protruding shaft, arranged at the center of the top surface of the disc cam, the top end of the protruding shaft passes through the protruding shaft hole of the positioning seat and is connected to the positioning seat; and Four identical arc edges, the arc edges are alternately connected with the straight edges of the disc cam to form the outer contour of the disc cam; Wherein, the disc cam is confined inside the positioning seat and its bottom surface contacts the upper end surface of the second plate portion, the transition between the arc edge and the straight edge of the disc cam is a rounded corner, and the distance from any point on the arc edge to the center of the disc cam is the maximum distance.

5. The self-centering assembly fixture according to claim 1, characterized in that: Each of the pointed top centering followers also includes: A pointed top moving block, having a movable hole penetrating the top surface and the bottom surface of the pointed top moving block, wherein the cross section of the movable hole is rectangular, the tip of the pointed top moving block is rounded, and the outer end thereof opposite to the tip has an arc surface having the same inner diameter as the assembled product, and the remaining side ends of the pointed top moving block are chamfered ends; A vertical fixing seat, the top end of which is fixedly connected to the top surface of the positioning seat and the bottom end of which is arranged in the movable hole of the pointed top moving block; A guide cross bar is arranged in the movable hole of the pointed top moving block along the corresponding axial direction, one end of the guide cross bar is fixedly connected to the bottom end of the vertical fixing seat and the other end thereof is at a distance from the inner wall corresponding to the movable hole in the pointed top moving block; and A spring, sleeved on the guide cross bar, one end of the spring is connected to the inner wall of the movable hole in the pointed top moving block and the other end is connected to the bottom end of the vertical fixing seat; Wherein, when the self-centering assembly fixture is in a relaxed state, the compression amount of the spring is zero; when the self-centering assembly fixture is in a clamped state, the compression amount of the spring is maximum.

6. The self-centering assembly fixture according to claim 5, characterized in that: The positioning seat also includes an internal hole of the positioning seat for limiting the moving direction of the pointed top moving block in the self-centering mechanism.

7. The self-centering assembly fixture according to claim 1, characterized in that: The self-centering assembly fixture includes two anti-rotation fixing parts symmetrically arranged along the first axis or the second axis.

8. The self-centering assembly fixture according to claim 7, characterized in that: The anti-rotation fixing part comprises: A transverse fixing seat, one end of which is fixedly arranged on the bottom edge of the positioning seat and the other end of which has a groove penetrating the side of the transverse fixing seat; a connecting member, one end of which is embedded in the groove wall portion of the transverse fixing seat and the other end of which is located outside the transverse fixing seat; and The anti-rotation unit has one part arranged in the groove of the transverse fixing seat and connected through the connecting piece and the other part located on the outside of the transverse fixing seat, and an anti-rotation pad is arranged on the outer part of the transverse fixing seat with its surface close to the outer wall corresponding to the positioning seat.

9. The self-centering assembly fixture according to claim 1, characterized in that: The self-centering assembly fixture includes a handle whose length extends along the central axis direction. The top boss of the handle passes through the boss hole in the positioning seat and is fixedly connected to the bottom center of the disc cam in the self-centering mechanism, and its bottom is fixedly connected to the handle seat. The bottom of the handle seat has a hexagonal groove.

10. The self-centering assembly fixture according to claim 3, characterized in that: The self-centering assembly fixture includes at least one anti-rotation pin, and the second plate portion in the positioning seat also has at least one round waist-shaped track groove that runs through the top surface and the bottom surface, and the anti-rotation pin passes through the round waist-shaped track groove corresponding to the second plate portion in the positioning seat and is fixedly connected to the disc cam; Wherein, when the self-centering assembly fixture is in a relaxed state, the anti-rotation pin is located at one end of the round waist-shaped track groove; When the self-centering assembly fixture is in a clamped state, the stop pin is located at the other end of the round waist-shaped track groove; both ends of the round waist-shaped track groove are marked with markings indicating the loose state and clamped state of the self-centering assembly fixture.

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