Connecting mechanism and connecting piece

Abstract

The utility model discloses a connecting mechanism and a connecting piece. The connecting mechanism comprises a first plate; a second plate; the connecting piece comprises a flange head part, a shoulder part and a riveting part, the outer diameter of the flange head part is larger than that of the shoulder part, the outer diameter of the shoulder part is larger than that of the riveting part, and the connecting piece can be connected with the first plate through the riveting part; the second plate is provided with a first mounting position through which the shoulder part can penetrate but the flange head part cannot penetrate, so that the connecting piece riveted with the first plate can be detachably connected with the second plate through the flange head part and the shoulder part. The connecting piece has the advantages that after the connecting piece is riveted to the first plate, an I-shaped structure is provided together, the connecting piece and the second plate can be quickly mounted and dismounted, and the dismounted plate can be reused; the mounting modes of the connecting piece are diversified, and the connecting piece can be suitable for plates of various models, thicknesses and hardness.

Description

Technical Field

[0001] The utility model relates to a connecting device, in particular to a connecting mechanism and a connecting piece. Background Art

[0002] The description in this section merely provides background information related to the disclosure of the present utility model and does not constitute prior art.

[0003] In the prior art, connection devices such as riveted nuts and riveted screws are usually used to achieve fixed connection between two plates.

[0004] Currently, there is a need for a connecting device that can realize the rapid disassembly and assembly of two plates at the same time, has a variety of product installation methods, and is suitable for plates of different models and thicknesses.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present invention. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide a connecting mechanism and a connecting piece to address the deficiencies of the prior art, which can achieve rapid disassembly and assembly, diversify product installation methods, and are more widely applicable to plates of various models and thicknesses.

[0007] The embodiment of the present application discloses a connection mechanism, including:

[0008] First Plate;

[0009] Second plate;

[0010] A connecting piece, the connecting piece comprising a flange head, a shoulder and a riveted portion arranged in sequence from top to bottom along the axial direction, the outer diameter of the flange head is greater than the outer diameter of the shoulder, the outer diameter of the shoulder is greater than the outer diameter of the riveted portion, and the connecting piece can be connected to the first plate through the riveted portion;

[0011] The second plate is provided with a first installation position through which the shoulder can pass but not through which the flange head can pass, so that the connecting piece that has been riveted to the first plate can be detachably connected to the second plate through the flange head and the shoulder.

[0012] Furthermore, in the above-mentioned connecting mechanism, the second plate is also provided with a second mounting position, the diameter of the first mounting position is larger than the outer diameter of the shoulder and smaller than the outer diameter of the flange head, the diameter of the second mounting position is larger than the outer diameter of the flange head, and the second mounting position is connected to the first mounting position so that the shoulder can switch between the first mounting position and the second mounting position.

[0013] Furthermore, in the above-mentioned connecting mechanism, the second plate is provided with a non-closed first installation position, the diameter of the first installation position is larger than the outer diameter of the shoulder and smaller than the diameter of the flange head, and the shoulder is embedded in the first installation position from the side end of the second plate.

[0014] Furthermore, in the above-mentioned connecting mechanism, a plurality of tooth portions are provided between the bottom of the shoulder portion and the end surface of the riveted portion.

[0015] Furthermore, in the above-mentioned connecting mechanism, the internal structure of the riveted part is solid, a through hole or a countersunk hole.

[0016] Furthermore, in the above-mentioned connecting mechanism, the outer wall of the riveted portion is provided with a threaded portion connected to the first plate material.

[0017] Furthermore, in the above-mentioned connecting mechanism, the riveting part includes a replacement head, a material receiving groove and a supporting handle which are arranged in sequence from top to bottom along the axial direction, the diameter of the supporting handle is larger than the diameter of the material receiving groove and smaller than the diameter of the replacement head, part of the material of the first plate flows into the material receiving groove through the extrusion of the replacement head, and the bottom of the first plate is flush with the bottom of the supporting handle.

[0018] Furthermore, in the above-mentioned connection mechanism, the cross-sectional area of ​​the shoulder is larger than the cross-sectional area of ​​the replacement head, and a limiting surface is provided at one end of the shoulder close to the replacement head, and the limiting surface abuts against the upper end surface of the first plate.

[0019] Furthermore, in the above-mentioned connecting mechanism, the cross-sectional area of ​​the replacement head is consistent with that of the shoulder.

[0020] An embodiment of the present application also discloses a connecting piece, comprising a flange head, a shoulder and a riveted portion arranged in sequence along the axial direction, wherein the outer diameter of the flange head is greater than the outer diameter of the shoulder, and the outer diameter of the shoulder is greater than the outer diameter of the riveted portion.

[0021] Furthermore, in the above-mentioned connecting piece, a plurality of toothed portions are provided between the bottom of the shoulder portion and the end surface of the riveted portion.

[0022] Furthermore, in the above-mentioned connecting piece, the internal structure of the riveted part is solid, a through hole or a countersunk hole.

[0023] Furthermore, in the above-mentioned connecting piece, the outer wall of the riveted portion is provided with a threaded portion.

[0024] Furthermore, in the above-mentioned connecting piece, the riveted portion includes a replacement head, a material receiving groove and a support handle which are arranged in sequence from top to bottom along the axial direction, the diameter of the support handle is larger than the diameter of the material receiving groove and smaller than the diameter of the replacement head, part of the material of the first plate flows into the material receiving groove through the extrusion of the replacement head, and the bottom of the first plate is flush with the bottom of the support handle.

[0025] Furthermore, in the above-mentioned connecting member, the cross-sectional area of ​​the shoulder is larger than the cross-sectional area of ​​the replacement head, and a limiting surface is provided at one end of the shoulder close to the replacement head, and the limiting surface abuts against the upper end surface of the first plate.

[0026] Furthermore, in the above-mentioned connecting piece, the cross-sectional area of ​​the replacement head is consistent with that of the shoulder.

[0027] In summary, the above structure adopted in the embodiment of the utility model has the following advantages:

[0028] 1. The connection mechanism and the connection member described in the utility model, after the connection member is riveted to the first plate, jointly provide an I-shaped structure to achieve rapid installation and removal with the second plate;

[0029] 2. The connector described in the utility model has diversified installation methods and can be applied to plates of various models, thicknesses and hardnesses;

[0030] 3. After the connecting piece described in the utility model is installed and disassembled with the second plate, the second plate can be reused.

[0031] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and description and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 is a schematic diagram of a connection mechanism in an embodiment of the present application;

[0034] Figure 2 In the embodiment of this application Figure 1 A top view of

[0035] Figure 3 is another schematic diagram of the second plate in the embodiment of the present application;

[0036] Figures 4 to 9 is a cross-sectional view of a connection between a connecting member and a first plate in multiple embodiments of the present application;

[0037] Fig.10 and Fig.11 1 is a three-dimensional schematic diagram and a half-section schematic diagram of the connecting member in the first embodiment of the present application;

[0038] Fig.12 and Fig.13 is a three-dimensional schematic diagram and a half-section schematic diagram of the connecting member in the second embodiment of the present application;

[0039] Fig.14 and Fig.15 It is a three-dimensional schematic diagram and a half-section schematic diagram of the connecting member in the third embodiment of the present application;

[0040] Fig.16 and Fig.17 1 is a three-dimensional schematic diagram and a half-section schematic diagram of the connecting member in the fourth embodiment of the present application;

[0041] Fig.18 and Fig.19 It is a three-dimensional schematic diagram and a half-section schematic diagram of the connecting member in the fifth embodiment of the present application;

[0042] Fig. 20 and Fig.21 It is a three-dimensional schematic diagram and a half-section schematic diagram of the connecting piece in Example 6 of the present application.

[0043] The figure marks of the above drawings are: 10, flange head; 20, shoulder; 30, riveting part; 31, replacement head; 32, material storage groove; 33, support handle; 40, inner hole; 50, flower tooth part; 60, limiting surface; 70, first plate; 80, second plate; 81, first installation position; 82, second installation position. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this specification.

[0045] The following is an explanation of the implementation of the utility model through specific specific embodiments. Those skilled in the art can understand the advantages and effects of the utility model from the contents disclosed in this specification. The utility model can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed in various ways based on different viewpoints and applications without deviating from the concept of the utility model. In addition, the drawings of the utility model are only simple schematic illustrations and are not depicted according to actual dimensions. It is stated in advance. The following implementation methods will further explain the relevant technical contents of the utility model in detail, but the disclosed contents are not intended to limit the scope of protection of the utility model.

[0046] It should be understood that, although the terms "first", "second", "third", etc. may be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are mainly used to distinguish one component from another component, or one signal from another signal. In addition, the term "or" used herein may include any one or more combinations of the associated listed items depending on the actual situation.

[0047] Reference Figures 1 to 21 As shown, the embodiment of the present application discloses a connection mechanism, including:

[0048] A first plate 70;

[0049] A second plate 80;

[0050] A connecting piece, the connecting piece comprises a flange head 10, a shoulder 20 and a rivet portion 30 arranged in sequence from top to bottom along the axial direction, the outer diameter of the flange head 10 is greater than the outer diameter of the shoulder 20, the outer diameter of the shoulder 20 is greater than the outer diameter of the rivet portion 30, and the connecting piece can be connected to the first plate 70 through the rivet portion 30;

[0051] The second plate 80 is provided with a first installation position 81 through which the shoulder 20 can pass but not through which the flange head 10 can pass, so that the connecting piece that has been riveted to the first plate 70 can be detachably connected to the second plate 80 through the flange head 10 and the shoulder 20.

[0052] Specifically, refer to Figure 2In this embodiment, the second plate 80 is also provided with a second mounting position 82, the diameter of the first mounting position 81 is larger than the outer diameter of the shoulder 20 and smaller than the outer diameter of the flange head 10, the diameter of the second mounting position 82 is larger than the outer diameter of the flange head 10, and the second mounting position 82 is connected to the first mounting position 81, so that the shoulder 20 can be switched between the first mounting position 81 and the second mounting position 82, the first mounting position 81 and the second mounting position 82 can form a gourd-like shape, when connected or disassembled with the second plate 80, the shoulder 20 and the flange head 10 can pass through or out of the second mounting position 82, and the diameter of the flange head 10 is larger than the first mounting position 81, and the diameter of the first mounting position 81 is larger than the shoulder 20, so the flange head 10 cannot enter the first mounting position 81, but the shoulder 20 can enter the first mounting position 81.

[0053] Specifically, in this embodiment, the second plate 80 is provided with a non-closed first mounting position 81, the diameter of the first mounting position 81 is larger than the outer diameter of the shoulder 20 and smaller than the diameter of the flange head 10, and the shoulder 20 is embedded in the first mounting position 81 from the side end of the second plate 80. A single-side opening hole, a horn hole or other openings with a similar structure having the first mounting position 81 can be provided in the second plate 80, and the shoulder 20 can be directly inserted into the first mounting position 81 laterally to achieve rapid installation of the connector and the second plate 80. The shoulder 20 passes through the first mounting position 81 in the reverse direction to achieve rapid disassembly from the second plate 80, which can effectively and conveniently perform later maintenance, and the disassembled plate can be reused.

[0054] In this embodiment, the first plate 70 can be a metal plate, or other similar non-metallic plate that can undergo plastic deformation, and the second plate 80 is a replaceable plate for quick connection. The first plate 70 can be provided with through holes, waist-shaped holes, star-shaped holes, fish-eye holes, etc. to cooperate with the connector for installation, or it can be directly installed with the connector without openings; the connection method between the connector and the first plate 70 can be flanging, expansion riveting, self-locking, interference fit, rotary riveting, welding, and adhesive bonding. After the connector is connected to the first plate 70 to form an "I"-shaped structure, it can be quickly matched with the second plate 80 for connection or disassembly.

[0055] Specifically, refer to Figure 5 In this embodiment, based on the above structure, a plurality of toothed portions 50 may be provided between the bottom of the shoulder portion 20 and the end surface of the riveted portion 30. When connected with the first plate 70, the toothed portions 50 may play a guiding and reinforcing role. In addition, Figure 4 and Figure 5 The connection method between the riveted portion 30 and the first plate 70 is flanging or expansion riveting.

[0056] Specifically, in this embodiment or other embodiments, the internal structure of the riveted portion 30 may be solid, through-hole or countersunk, as shown in FIG. Figure 4 and Figure 5 , the riveting portion 30 is provided with an inner hole 40; Figure 6 The riveted portion 30 is a solid structure, and the riveted portion 30 is connected to the first plate 70 by cold heading and flanging.

[0057] Specifically, refer to Figure 7 In another embodiment, the outer wall of the riveted portion 30 is provided with a threaded portion connected to the first plate 70, and part of the material of the first plate 70 is squeezed along the texture of the threaded portion and flows into the threaded portion, thereby realizing a self-locking connection structure between the threaded portion and the first plate 70.

[0058] Specifically, refer to Figure 8 In another embodiment, the riveted portion 30 includes a replacement head 31, a material receiving groove 32 and a support handle 33 which are sequentially arranged from top to bottom along the axial direction. The diameter of the support handle 33 is larger than the diameter of the material receiving groove 32 and smaller than the diameter of the replacement head 31. The cross-sectional area of ​​the shoulder 20 is larger than the cross-sectional area of ​​the replacement head 31. A limiting surface 60 is provided at one end of the shoulder 20 close to the replacement head 31, and the limiting surface 60 abuts against the upper end surface of the first plate 70. Part of the material of the first plate 70 flows into the material receiving groove 32 through the extrusion of the replacement head 31. The bottom of the first plate 70 is flush with the bottom of the support handle 33. The first plate 70 is connected to the riveted portion 30 in a self-locking manner.

[0059] Specifically, refer to Fig. 9 In another embodiment, the riveted portion 30 includes a replacement head 31, a material receiving groove 32 and a support handle 33 which are sequentially arranged from top to bottom along the axial direction. The diameter of the support handle 33 is larger than the diameter of the material receiving groove 32 and smaller than the diameter of the replacement head 31. The cross-sectional area of ​​the replacement head 31 is consistent with the shoulder 20. Part of the material of the first plate 70 flows into the material receiving groove 32 through the extrusion of the replacement head 31. The bottom of the first plate 70 is flush with the bottom of the support handle 33. The first plate 70 is connected to the riveted portion 30 in a self-locking manner.

[0060] In particular, the above-mentioned connection mechanism can be applied to the connection of the first plate 70 or the second plate 80 alone.

[0061] In summary, compared with the prior art, the connecting mechanism in the embodiment of the present application has the following advantages: the connecting mechanism and the connecting member, after the connecting member is riveted to the first plate, jointly provide an I-shaped structure to achieve rapid installation and disassembly with the second plate; the installation method of the connecting member is diversified, and can be applicable to plates of various models, thicknesses, and hardnesses; after the connecting member and the second plate are installed and disassembled, the second plate can be reused.

[0062] Reference Figures 10 to 21 The present application also discloses a connector. The present invention is described in detail below through specific embodiments:

[0063] Embodiment 1

[0064] Reference Fig.10 and Fig.11 In this embodiment, the connecting member includes a flange head 10, a shoulder 20 and a riveted portion 30 which are arranged in sequence along the axial direction. The outer diameter of the flange head 10 is greater than the outer diameter of the shoulder 20, and the outer diameter of the shoulder 20 is greater than the outer diameter of the riveted portion 30. In this embodiment, an inner hole 40 is provided inside the riveted portion 30.

[0065] Embodiment 2

[0066] Reference Fig.12 and Fig.13 In this embodiment, the connecting piece includes a flange head 10, a shoulder 20 and a riveted portion 30 which are sequentially arranged along the axial direction. The outer diameter of the flange head 10 is greater than the outer diameter of the shoulder 20, and the outer diameter of the shoulder 20 is greater than the outer diameter of the riveted portion 30. In this embodiment, an inner hole 40 is provided inside the riveted portion 30, and a plurality of tooth portions 50 are provided between the bottom of the shoulder 20 and the end face of the riveted portion 30. When connected with the plate, the tooth portion 50 can play a guiding and reinforcing role.

[0067] Embodiment 3

[0068] Reference Fig.14 and Fig.15 In this embodiment, the connecting member includes a flange head 10, a shoulder 20 and a riveted portion 30 arranged in sequence along the axial direction. The outer diameter of the flange head 10 is greater than the outer diameter of the shoulder 20, and the outer diameter of the shoulder 20 is greater than the outer diameter of the riveted portion 30. In this embodiment, the internal structure of the riveted portion 30 is solid.

[0069] Embodiment 4

[0070] Reference Fig.16 and Fig.17In this embodiment, the connecting member includes a flange head 10, a shoulder 20 and a riveted portion 30 arranged in sequence along the axial direction. The outer diameter of the flange head 10 is greater than the outer diameter of the shoulder 20, and the outer diameter of the shoulder 20 is greater than the outer diameter of the riveted portion 30. In this embodiment, the internal structure of the riveted portion 30 is solid, and the outer wall of the riveted portion 30 is provided with a threaded portion.

[0071] Embodiment 5

[0072] Reference Fig.18 and 19 In this embodiment, the connecting member includes a flange head 10, a shoulder 20 and a riveted portion 30 which are sequentially arranged along the axial direction, the outer diameter of the flange head 10 is greater than the outer diameter of the shoulder 20, the outer diameter of the shoulder 20 is greater than the outer diameter of the riveted portion 30, wherein the riveted portion 30 includes a replacement head 31, a material receiving groove 32 and a support handle 33 which are sequentially arranged from top to bottom along the axial direction, the diameter of the support handle 33 is greater than the diameter of the material receiving groove 32 and smaller than the diameter of the replacement head 31, and the replacement head 31 can extrude part of the plate connected thereto into the material receiving groove 32.

[0073] Specifically, in this embodiment, the cross-sectional area of ​​the shoulder 20 is larger than the cross-sectional area of ​​the replacement head 31 , and a limiting surface 60 is provided at one end of the shoulder 20 close to the replacement head 31 , and the limiting surface 60 can abut against the upper end surface of the connecting plate.

[0074] Embodiment 6

[0075] Reference Fig. 20 and Fig.21 In this embodiment, the connecting member includes a flange head 10, a shoulder 20 and a riveted portion 30 which are sequentially arranged along the axial direction, the outer diameter of the flange head 10 is greater than the outer diameter of the shoulder 20, the outer diameter of the shoulder 20 is greater than the outer diameter of the riveted portion 30, wherein the riveted portion 30 includes a replacement head 31, a material receiving groove 32 and a support handle 33 which are sequentially arranged from top to bottom along the axial direction, the diameter of the support handle 33 is greater than the diameter of the material receiving groove 32 and smaller than the diameter of the replacement head 31, the replacement head 31 can extrude part of the plate connected thereto into the material receiving groove 32, and the cross-sectional area of ​​the replacement head 31 is consistent with that of the shoulder 20.

[0076] In the present application, the flange head of the connector can be a curved head shape, and the various structures of the riveted part diversify its installation methods. In addition, the material characteristics of the connector include aluminum, copper, carbon steel, stainless steel and other non-ferrous metal materials.

[0077] The contents disclosed above are only preferred feasible embodiments of the present utility model, and are not intended to limit the scope of the patent application of the present utility model. Therefore, all equivalent technical changes made using the contents of the specification and drawings of the present utility model are included in the scope of the patent application of the present utility model.

[0078] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present application can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld devices or portable devices, tablet devices, multi-processor systems, microprocessor-based systems, set-top boxes, programmable electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, etc.

[0079] Although the present application has been described through embodiments, those skilled in the art will appreciate that there are many modifications and changes to the present application without departing from the spirit of the present application. It is intended that the attached embodiments include these modifications and changes without departing from the present application.

Claims

1. A connecting mechanism, characterized in that: include: First Plate; Second plate; A connecting piece, the connecting piece comprising a flange head, a shoulder and a riveted portion arranged in sequence from top to bottom along the axial direction, the outer diameter of the flange head is greater than the outer diameter of the shoulder, the outer diameter of the shoulder is greater than the outer diameter of the riveted portion, and the connecting piece can be connected to the first plate through the riveted portion; The second plate is provided with a first installation position through which the shoulder can pass but not through which the flange head can pass, so that the connecting piece that has been riveted to the first plate can be detachably connected to the second plate through the flange head and the shoulder.

2. The connection mechanism according to claim 1, characterized in that: The second plate is also provided with a second mounting position, the diameter of the first mounting position is larger than the outer diameter of the shoulder and smaller than the outer diameter of the flange head, the diameter of the second mounting position is larger than the outer diameter of the flange head, and the second mounting position is connected to the first mounting position so that the shoulder can switch between the first mounting position and the second mounting position.

3. The connection mechanism according to claim 1, characterized in that: The second plate is provided with a non-closed first installation position, the diameter of the first installation position is larger than the outer diameter of the shoulder and smaller than the diameter of the flange head, and the shoulder is embedded in the first installation position from the side end of the second plate.

4. The connection mechanism according to claim 2 or 3, characterized in that: A plurality of tooth portions are arranged between the bottom of the shoulder portion and the end surface of the riveting portion.

5. The connection mechanism according to claim 2 or 3, characterized in that: The internal structure of the riveted part is solid, a through hole or a countersunk hole.

6. The connection mechanism according to claim 2 or 3, characterized in that: The outer wall of the riveted portion is provided with a threaded portion connected to the first plate.

7. The connection mechanism according to claim 2 or 3, characterized in that: The riveting portion includes a replacement head, a material receiving groove and a support handle which are arranged in sequence from top to bottom along the axial direction. The diameter of the support handle is larger than the diameter of the material receiving groove and smaller than the diameter of the replacement head. Part of the material of the first plate flows into the material receiving groove through the extrusion of the replacement head, and the bottom of the first plate is flush with the bottom of the support handle.

8. The connection mechanism according to claim 7, characterized in that: The cross-sectional area of ​​the shoulder is larger than the cross-sectional area of ​​the replacement head. A limiting surface is provided at one end of the shoulder close to the replacement head, and the limiting surface abuts against the upper end surface of the first plate.

9. The connection mechanism according to claim 7, characterized in that: The cross-sectional area of ​​the replacement head is consistent with that of the shoulder.

10. A connecting piece, characterized in that: It includes a flange head, a shoulder and a riveted portion which are sequentially arranged along the axial direction, the outer diameter of the flange head is larger than the outer diameter of the shoulder, the outer diameter of the shoulder is larger than the outer diameter of the riveted portion, and the riveted portion is used to connect with the first plate.

11. The connecting piece according to claim 10, characterized in that: A plurality of tooth portions are arranged between the bottom of the shoulder portion and the end surface of the riveting portion.

12. The connecting piece according to claim 10, characterized in that: The internal structure of the riveted part is solid, a through hole or a countersunk hole.

13. The connecting piece according to claim 10, characterized in that: The outer wall of the riveting part is provided with a threaded part.

14. The connecting piece according to claim 10, characterized in that: The riveting portion includes a replacement head, a material receiving groove and a support handle which are arranged in sequence from top to bottom along the axial direction. The diameter of the support handle is larger than the diameter of the material receiving groove and smaller than the diameter of the replacement head. Part of the material of the first plate flows into the material receiving groove through the extrusion of the replacement head, and the bottom of the first plate is flush with the bottom of the support handle.

15. The connecting piece according to claim 14, characterized in that The cross-sectional area of ​​the shoulder is larger than the cross-sectional area of ​​the replacement head. A limiting surface is provided at one end of the shoulder close to the replacement head, and the limiting surface abuts against the upper end surface of the first plate.

16. The connecting piece according to claim 14, characterized in that The cross-sectional area of ​​the replacement head is consistent with that of the shoulder.

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