Expansion peg and connection structure for a vehicle

Abstract

The present application relates to a kind of expansion rivet and connecting structure for vehicle, the expansion rivet, including: sub buckle, sub buckle includes end cap portion and the insertion portion connected to end cap portion, first recess is equipped on the outer circumferential surface of insertion portion;And female buckle, female buckle includes flange portion, multiple elastic sheets, first protruding portion and second protruding portion, flange portion is provided with the through hole of insertion portion insertion, multiple elastic sheets are connected to flange portion and are arranged at intervals around through hole;First protruding portion and second protruding portion are respectively spaced apart and arranged on the inner side of elastic sheet along the axial direction;First protruding portion is matched with first recess, when first protruding portion is arranged in first recess, second protruding portion is in contact with the outer circumferential surface of insertion portion to radially open elastic sheet, so that expansion rivet is in locked state;In locked state, due to the clamping of first protruding portion and first recess, it can prevent sub buckle reverse back, ensure that the impact generated by vibration during the driving of vehicle will not eject sub buckle, so as to prevent the gradual loosening and abnormal sound of expansion rivet due to vibration.

Description

Technical Field

[0001] This invention relates to the field of vehicle parts assembly technology, and in particular to an expansion clip and a connection structure for vehicles. Background Technology

[0002] Expansion clips are commonly used fasteners for connecting automotive exterior trim and underbody protection panels to sheet metal parts. They rely on internal pushing to expand the outer diameter and frictionally lock into the plate holes of the sheet metal parts. They are characterized by easy installation and removal, and are waterproof and shockproof. Most existing expansion clips adopt a split structure, including a slotted outer sleeve and a push-in core pin.

[0003] In the connection between automotive trim parts and sheet metal parts, due to shape and space limitations, it is often necessary to add mounting points at the edges of the sheet metal. However, due to space constraints, bolts cannot be used for tightening, and expansion clips must be used for fixing. However, vibrations generated during actual vehicle operation can easily push the core pin of the expansion clip backwards, causing the expansion clip connection to fail. This is especially true when adapting to thick sheet metal (e.g., sheet metal parts with a thickness of 4mm to 7mm), because the expansion clip needs to penetrate a relatively deep hole to unfold, the constraint force of the expansion clip on the core pin is weaker, making it more prone to retraction and detachment under impact. Summary of the Invention

[0004] To address the issue that existing expansion clips can easily push the core pin out in the opposite direction, an expansion clip and a connection structure for vehicles are provided.

[0005] On one hand, this application provides an expansion clip, comprising: a male clip, the male clip including an end cap and an insertion portion connected to the end cap, the insertion portion having a first groove on its outer peripheral surface; and a female clip, the female clip including a flange, a plurality of spring pieces, a first protrusion and a second protrusion, the flange having a through hole for inserting the insertion portion, the plurality of spring pieces being connected to the flange and spaced apart around the through hole; the first protrusion and the second protrusion being axially spaced apart on the inner side surface of the spring pieces; the first protrusion matching the first groove, when the first protrusion is engaged in the first groove, the second protrusion abuts against the outer peripheral surface of the insertion portion to radially open the spring pieces, so that the expansion clip is in a locked state.

[0006] In one embodiment, the outer peripheral surface of the insertion portion is provided with a second groove that matches the first protrusion, and the second groove is located on the side of the first groove away from the end cap portion.

[0007] In one embodiment, both the second groove and the first groove are annular grooves extending circumferentially along the insertion portion.

[0008] In one embodiment, the outer peripheral surface of the spring is an arc-shaped surface, and multiple springs are gathered to form a sleeve-like structure, and the diameter of the inner hole formed by multiple second protrusions is smaller than the diameter of the insertion part.

[0009] In one embodiment, the second protrusion has a guide surface that extends forward at an angle from the inner side of the spring.

[0010] In one embodiment, the sub-button further includes a guide portion disposed at the front end of the insertion portion, the guide portion having a guide surface, the angle between the guide surface and the axis of the insertion portion being less than or equal to the angle between the guide surface and the axis of the insertion portion.

[0011] In one embodiment, in the pre-assembled state, the outer diameter of the sleeve-shaped structure is less than or equal to 8 mm.

[0012] In one embodiment, the axial distance between the second protrusion and the flange ranges from 4.9 mm to 7.1 mm.

[0013] In one embodiment, the first protrusion has a guide slope on the side facing the flange.

[0014] On the other hand, this application provides a connection structure for a vehicle, comprising: an expansion pin as described above; a first plate having a first through hole; and a second plate having a second through hole, the second plate being stacked on top of the first plate, the second through hole being aligned with the first through hole, the female buckle of the expansion pin being sequentially inserted through the first through hole and the second through hole, and the male buckle of the expansion pin being inserted into the female buckle of the expansion pin, so that the female buckle of the expansion pin expands and clamps the hole wall of the second through hole.

[0015] The expansion clips of this application require no tools during installation; they can be expanded and secured simply by hand pressure. This simplifies installation and removal, and increases maintenance efficiency. Multiple spring clips expand to fit the entire circumference, resulting in more even force distribution, strong vibration resistance, and reduced loosening, ensuring no abnormal noises during vehicle operation. The flange covers the holes, and with the rubber ring, it provides dustproof, waterproof, or sandproof protection against dirt and sand entering the sheet metal holes.

[0016] The expansion clip of this application has a locked state. In the locked state, the insertion part drives the portion of the spring piece that has passed through the sheet metal hole to expand radially outward through the second protrusion, so that the spring piece makes uniform circumferential contact with the hole wall, increasing the effective contact area between the spring piece and the hole wall, thereby providing sufficient expansion locking force. In addition, since the first protrusion engages with the first groove, it can prevent the clip from retracting in the opposite direction, ensuring that the impact generated by vibration during vehicle operation will not push the clip out, thereby preventing the expansion clip from gradually loosening and making abnormal noise due to vibration.

[0017] The expansion clip of this application has a pre-installed state, in which the female and male clips can be pre-fixed, facilitating the transportation of the expansion clip; and when connecting sheet metal parts, the female and male clips can be inserted into the sheet metal hole simultaneously, making the operation more convenient and faster. In addition, the spring clip of the female clip remains closed as a whole, and the outer contour diameter of multiple spring clips is smaller than the diameter of the sheet metal hole, allowing the spring clips to pass through the entire sheet metal hole of the thick sheet metal part with low resistance. Attached Figure Description

[0018] Figure 1 A schematic diagram of a vehicle connection structure provided in one embodiment of this application; Figure 2 A cross-sectional schematic diagram of a vehicle connection structure according to the above embodiments of this application is shown; Figure 3 A schematic diagram of an expansion clip provided for one embodiment of this application; Figure 4 A schematic diagram is shown of the expansion pin in the locked state according to the above embodiments of this application; Figure 5 A cross-sectional schematic diagram of the expansion pin in the locked state according to the above embodiment of this application is shown; Figure 6 As shown Figure 5 A magnified view of part A of the expansion clip shown; Figure 7 A schematic diagram of the expansion clip according to the above embodiments of this application in a pre-installed state is shown; Figure 8 A cross-sectional schematic diagram of the expansion clip according to the above embodiments of this application in a pre-installed state is shown; Figure 9 As shown Figure 8 A magnified view of part B of the expansion pin shown; Figure 10 A cross-sectional schematic diagram of the female buckle of the expansion pin according to the above embodiments of this application is shown; Figure 11 A schematic diagram of the sub-buckle of the expansion pin according to the above embodiment of this application is shown.

[0019] Figure label: 10. Expansion pin; 11. Female buckle; 111. End cap; 112. Insertion part; 113. First groove; 114. Second groove; 115. Guide part; 12. Female buckle; 121. Flange part; 122. Spring piece; 123. Through hole; 124. First protrusion; 125. Second protrusion; 126. Countersunk groove; 20. First plate; 21. First through hole; 30. Second plate; 31. Second through hole. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0025] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0026] Specifically, please refer to Figure 1 and Figure 2 This application provides a vehicle connection structure, which may include a first plate 20, a second plate 30, and an expansion bolt 10. Both the first plate 20 and the second plate 30 can be implemented as sheet metal parts or automotive trim parts, respectively. The first plate 20 has a first through hole 21, and the second plate 30 has a second through hole 31. The second plate 30 is stacked on top of the first plate 20, aligning the second through hole 31 with the first through hole 21. The expansion bolt 10 includes a female buckle 12 and a female buckle 11. The female buckle 12 passes sequentially through the first through hole 21 and the second through hole 31, and the female buckle 11 of the expansion bolt 10 is inserted into the female buckle 12, causing the female buckle 12 to expand and lock into the wall of the second through hole 31.

[0027] More specifically, please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 10 and Figure 11The expansion snag 10 includes a male snag 11 and a female snag 12. The male snag 11 includes an end cap 111 and an insertion portion 112. The insertion portion 112 is connected to the end cap 111, and a first groove 113 is provided on the outer peripheral surface of the insertion portion 112. The female snag 12 includes a flange 121 and a plurality of spring tabs 122. The flange 121 has a through hole 123 for inserting the insertion portion 112. The plurality of spring tabs 122 are respectively connected to the flange 121 and arranged around the through hole 123. A first protrusion 124 and a second protrusion 125 are provided axially spaced on the inner side of each spring tab 122. The first protrusion 124 matches the first groove 113. When the first protrusion 124 is engaged in the first groove 113, the second protrusion 125 abuts against the outer peripheral surface of the insertion portion 112 to radially open the spring tab 122, so that the expansion snag 10 is in a locked state.

[0028] like Figure 2 As shown, when using the expansion clip 10 to fix the first plate 20 and the second plate 30, the spring piece 122 of the female buckle 12 can be inserted sequentially into the first through hole 21 and the second through hole 31, so that the flange part 121 of the female buckle 12 abuts against the first plate 20. Then, press the end cap part 111 of the male buckle 11 and insert the insertion part 112 between the second protrusions 125. The spring piece 122 is pushed radially outward by the second protrusions 125 to clamp the hole wall of the second through hole 31, thereby clamping the first plate 20 and the second plate 30 together.

[0029] Understandably, the expansion clip 10 requires no tools during installation; it expands and secures itself simply by hand pressure, making disassembly and assembly easy and maintenance highly efficient. Multiple spring clips 122 expand to fit the entire circumference, resulting in more even force distribution, strong vibration resistance, and reduced loosening, ensuring no abnormal noises during vehicle operation. The flange 121 conceals the holes, and together with the rubber ring, provides dustproofing, waterproofing, or prevention of mud and sand from entering the sheet metal holes.

[0030] In the locked state, the insertion part 112 drives the portion of the spring piece 122 that has passed through the sheet metal hole to expand radially outward via the second protrusion 125, so that the spring piece 122 makes uniform circumferential contact with the hole wall, increasing the effective contact area between the spring piece 122 and the hole wall, thereby providing sufficient expansion locking force. In addition, since the first protrusion 124 engages with the first groove 113, it can prevent the buckle 11 from retracting in the opposite direction, ensuring that the impact generated by the vibration during vehicle operation will not push the buckle 11 out, thereby preventing the expansion pin 10 from gradually loosening and making abnormal noise due to vibration.

[0031] Alternatively, in some embodiments, such as Figure 7 , Figure 8 and Figure 9As shown, the first protrusion 124 is located between the second protrusion 125 and the end cap 111. The female buckle 12 may include only one first protrusion 124 and one second protrusion 125, wherein the first protrusion 124 and the second protrusion 125 may protrude from the same spring piece 122, or the first protrusion 124 and the second protrusion 125 may protrude from different spring pieces 122. The female buckle 12 may also include multiple first protrusions 124 and multiple second protrusions 125, with each spring piece 122 having a first protrusion 124 and a second protrusion 125 protruding at intervals along the axial direction.

[0032] In the connection between automotive trim parts and sheet metal parts, the expansion clip 10 is subject to limitations imposed by the vehicle's shape and space constraints, making it inconvenient to insert the female clip 12 and the female clip 11 into the sheet metal holes separately. Therefore, in some embodiments, the outer peripheral surface of the insertion part 112 is provided with a second groove 114 that matches the first protrusion 124. The second groove 114 is located on the side of the first groove 113 away from the end cap 111. When the first protrusion 124 is engaged in the second groove 114, the second protrusion 125 is located on the front side of the insertion part 112, putting the expansion clip 10 in a pre-installed state. In this way, in the pre-installed state, the female clip 12 and the female clip 11 can be pre-fixed, facilitating the transportation of the expansion clip 10; and when connecting sheet metal parts, the female clip 12 and the female clip 11 can be inserted into the sheet metal holes simultaneously, making the operation more convenient and faster. In addition, the spring clips 122 of the female buckle 12 remain closed as a whole, and the outer diameter of the multiple spring clips 122 is smaller than the diameter of the sheet metal hole, so that the spring clips 122 can pass through the entire sheet metal hole of the thick sheet metal part with low resistance.

[0033] Alternatively, in some embodiments, such as Figure 11 As shown, both the second groove 114 and the first groove 113 are annular grooves extending circumferentially along the insertion portion 112. Thus, when the first protrusion 124 is engaged in the second groove 114 or the first groove 113, the male buckle 11 and the female buckle 12 can rotate freely. In the pre-installed state, this facilitates adjusting the orientation of the end cap 111 according to the actual space. In the locked state, when the vehicle vibrates, the male buckle 11 and the female buckle 12 can release the torsional stress generated by the vibration through relative rotation, preventing the spring clip 122 from fatigue cracking due to long-term torque, and improving the durability of the expansion pin 10.

[0034] Optionally, in some embodiments, the outer peripheral surface of the spring piece 122 is an arc-shaped surface, and multiple spring pieces 122 together form a sleeve-like structure. In this way, the outer contour of the sleeve-like structure formed by the spring pieces 122 fits more closely to the wall of the circular sheet metal hole, which can increase the circumferential contact area, so that the expansion locking force is evenly distributed along the hole wall, avoiding local deformation or loosening caused by stress concentration.

[0035] Optionally, in some embodiments, the female latch 12 includes at least three spring tabs 122, each spring tab 122 being evenly distributed circumferentially around the through hole 123. In this way, after the three spring tabs 122 are unfolded, they form multi-point uniform support along the wall of the sheet metal hole, and the expansion locking force is centrally symmetrically distributed in the circumferential direction. The three spring tabs 122 are mutually balanced, which can maintain a more stable locking state.

[0036] Optionally, in some embodiments, the diameter of the inner hole formed by the plurality of second protrusions 125 is smaller than the diameter of the insertion portion 112. In this way, when the insertion portion 112 is inserted between the second protrusions 125, it can compress each spring piece 122 through the second protrusions 125, causing each spring piece 122 to expand radially outward.

[0037] Optionally, in some embodiments, the second protrusion 125 has a guide surface that extends forward at an angle from the inner side of the spring tab 122. Thus, the radial distance between the guide surface and the axis of the insertion portion 112 gradually decreases from the end near the flange portion 121 to the end away from the flange portion 121. When the snap fastener 11 is inserted, the outer peripheral surface of the insertion portion 112 slides gradually along the guide surface, causing the second protrusion 125 to be smoothly pushed open. The contact pressure between the spring tab 122 and the hole wall continuously increases from zero, and the expansion locking force increases synchronously and gradually, making the insertion of the snap fastener 11 easier.

[0038] Alternatively, in some embodiments, such as Figure 8 and Figure 11 As shown, the buckle 11 also includes a guide portion 115 disposed at the front end of the insertion portion 112. The guide portion 115 has a guide surface, and the angle between the guide surface and the axis of the insertion portion 112 is less than or equal to the angle between the guide surface and the axis of the insertion portion 112. In other words, the slope of the guide surface is less than or equal to the slope of the guide surface. During insertion, the guide portion 115 first enters between the second protrusions 125, and then the outer peripheral surface of the insertion portion 112 disengages from the guide surface, so that the second protrusions 125 are smoothly lifted up. This avoids the insertion portion 112 from being unable to insert between multiple second protrusions 125 due to the front end directly impacting the second protrusions 125, and prevents the buckle 11 from getting stuck.

[0039] Optionally, in some embodiments, in the pre-installed state, the outer diameter of the sleeve-like structure formed by the multiple spring clips 122 is less than or equal to 8 mm. In this way, the expansion pin 10 can fit the sheet metal hole of the sheet metal part with a diameter of 8±0.1 mm. During the insertion process, the spring clips 122 form a clearance fit or a slight transition fit with the hole wall, which reduces the insertion resistance and avoids unexpected frictional expansion.

[0040] Alternatively, in some embodiments, such as Figure 8As shown, the axial distance T between the second protrusion 125 and the flange 121 ranges from 4.9 mm to 7.1 mm. The portion of the spring clip 122 located between the second protrusion 125 and the flange 121 is used to pass through the sheet metal hole, so that the expansion bolt 10 can be adapted to connect sheet metal parts with a total thickness of 4.9 mm to 7.1 mm.

[0041] Alternatively, in some embodiments, such as Figure 10 As shown, one of the spring pieces 122 has two first protrusions 124. In the circumferential direction, a second protrusion 125 is located in the middle of the spring piece 122. The two first protrusions 124 are symmetrically arranged on both sides of the second protrusion 125 along the axial direction. In this way, the second protrusion 125 is located in the middle of the spring piece 122, so that the spring piece 122 is lifted and the point of action of the expansion is located in the middle of the spring piece 122. The spring piece 122 can produce uniform deformation, thereby more uniformly fitting with the hole wall of the sheet metal hole, making the connection between the expansion pin 10 and the sheet metal part more secure.

[0042] Alternatively, in some embodiments, such as Figure 9 As shown, the first protrusion 124 has a guide slope on the side facing the flange 121. This guide slope can play a guiding role. When the snap fastener 11 is inserted, the outer peripheral surface of the insertion part 112 slides smoothly over the first protrusion 124 along the guide slope. When the snap fastener 11 is pushed from the pre-installed state to the locked state, the first protrusion 124 slides smoothly out of the groove of the second groove 114 under the guidance of the guide slope, which reduces the sliding resistance between the first protrusion 124 and the edge of the groove and eliminates the jamming caused by the first protrusion 124 and the second groove 114.

[0043] Alternatively, in some embodiments, such as Figure 3 and Figure 10 As shown, the flange portion 121 has a recessed groove 126, and a through hole 123 is formed at the bottom of the groove 126. The diameter of the groove 126 is greater than or equal to the diameter of the end cap portion 111. In the locked state, the end cap portion 111 is located within the groove 126. This eliminates the interference in the assembly space caused by the protrusion of the end cap portion 111 and avoids scratching surrounding parts in a confined space.

[0044] Optionally, in some embodiments, both the male buckle 11 and the female buckle 12 are made of nylon material. Nylon material has good corrosion resistance and electrical insulation, and will not produce electrochemical corrosion when in contact with body sheet metal parts, avoiding the common problems of rust and hole enlargement caused by rust on sheet metal holes in metal fasteners. At the same time, the density of nylon material is significantly lower than that of metal, which is beneficial to the lightweight design of the whole vehicle. Moreover, nylon can be integrally molded by injection molding, which has high processing efficiency and low mold cost, so that the expansion bolt 10 has both excellent weather resistance and economy while having sufficient structural strength.

[0045] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0046] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An expansion clip, characterized in that, include: The sub-buckle includes an end cap and an insertion portion connected to the end cap, wherein a first groove is provided on the outer peripheral surface of the insertion portion; and The female fastener includes a flange portion, multiple spring clips, a first protrusion, and a second protrusion. The flange portion has a through hole for inserting the insertion part. The multiple spring clips are connected to the flange portion and arranged at intervals around the through hole. The first protrusion and the second protrusion are respectively spaced out on the inner side of the spring clip along the axial direction. The first protrusion matches the first groove. When the first protrusion is engaged in the first groove, the second protrusion abuts against the outer peripheral surface of the insertion part to radially open the spring clip, so that the expansion pin is in a locked state.

2. The expansion clip according to claim 1, characterized in that, The outer peripheral surface of the insertion part is provided with a second groove that matches the first protrusion, and the second groove is located on the side of the first groove away from the end cap.

3. The expansion clip according to claim 2, characterized in that, Both the second groove and the first groove are annular grooves extending circumferentially along the insertion portion.

4. The expansion clip according to any one of claims 1 to 3, characterized in that, The outer peripheral surface of the spring is an arc-shaped surface, and multiple springs together form a sleeve-like structure. The diameter of the inner hole formed by multiple second protrusions is smaller than the diameter of the insertion part.

5. The expansion clip according to any one of claims 1 to 3, characterized in that, The second protrusion has a guide surface that extends forward at an angle from the inner side of the spring piece.

6. The expansion clip according to claim 5, characterized in that, The sub-button also includes a guide portion disposed at the front end of the insertion portion. The guide portion has a guide surface, and the angle between the guide surface and the axis of the insertion portion is less than or equal to the angle between the guide surface and the axis of the insertion portion.

7. The expansion clip according to claim 4, characterized in that, The outer diameter of the sleeve-shaped structure is less than or equal to 8 mm.

8. The expansion clip according to any one of claims 1 to 3, characterized in that, The axial distance between the second protrusion and the flange ranges from 4.9 mm to 7.1 mm.

9. The expansion clip according to any one of claims 1 to 3, characterized in that, The first protrusion has a guide slope on the side facing the flange.

10. A connection structure for a vehicle, characterized in that, include: The expansion pin as described in any one of claims 1 to 9; A first plate, wherein the first plate has a first through hole; as well as The second plate has a second through hole. The second plate is stacked on top of the first plate. The second through hole is aligned with the first through hole. The female buckle of the expansion pin is sequentially inserted into the first through hole and the second through hole. The male buckle of the expansion pin is inserted into the female buckle of the expansion pin so that the female buckle of the expansion pin expands and locks the hole wall of the second through hole.

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