Fabricated building outer wall connecting structure

Abstract

The utility model provides an assembly type building outer wall connecting structure which comprises a floor slab, a lower outer wall plate, a top connecting plate and lower connecting angle steel. The lower external wall panel is arranged below the floor slab, the upper end of the lower external wall panel abuts against the lower surface of the floor slab and is provided with a lower pre-embedded connecting piece, and one end of the lower pre-embedded connecting piece extends out of the side, away from the building external facade, of the lower external wall panel; the top connecting plate is connected with one end, extending out of the lower external wall panel, of the lower embedded connecting piece; the lower connecting angle steel is provided with a first fixing plate and a second fixing plate which are arranged in a right-angle crossing mode, the first fixing plate is used for being fixedly connected with the embedded fixing piece, and the second fixing plate is used for being fixedly connected with the top connecting plate. According to the utility model, the lower pre-embedded connecting piece is pre-embedded in the lower external wall panel, so that a certain wall thickness can be reserved between the lower pre-embedded connecting piece made of a metal material and the external facade of the building, the cold bridge effect at the position is weakened, and the overall thermal insulation and waterproof performance of the composite external wall panel is further ensured.

Description

Technical Field

[0001] This utility model belongs to the field of prefabricated building technology, specifically relating to a prefabricated building exterior wall connection structure. Background Technology

[0002] Prefabricated buildings refer to buildings constructed by prefabricating building components and accessories (such as floor slabs, wall panels, stairs, balconies, etc.) in a factory, then transporting them to the construction site for assembly. Compared with traditional construction methods, prefabricated buildings have advantages such as shorter construction cycles, lower noise, energy conservation, and environmental friendliness, and have been widely used. Precast exterior wall panels are a type of component in prefabricated buildings, installed as exterior walls on the building facade. Precast exterior wall panels not only fulfill the load-bearing and partitioning functions of conventional wall panels, but also provide insulation and waterproofing, preventing rainwater from seeping into the interior through the joints. Achieving excellent waterproofing and insulation performance depends not only on the material properties and structural design of the precast exterior wall panels themselves, but also on their overall construction and construction techniques.

[0003] In existing technologies, when connecting precast exterior wall panels to floor slabs, holes are typically pre-drilled at the ends of the precast exterior wall panels. Metal connectors (such as hook bolts and flat bolts) are then inserted into these holes to connect with the embedded parts in the floor slab. The exposed side of the metal connector is then filled with insulating mortar. This connection method results in the location of the metal connector becoming a weak point in the building envelope system, leading to poor thermal insulation and waterproofing. Utility Model Content

[0004] This utility model provides a prefabricated building exterior wall connection structure, which aims to improve the thermal insulation and waterproofing performance at the connection points between prefabricated exterior wall panels and floor slabs.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is: to provide a prefabricated building exterior wall connection structure, comprising:

[0006] The floor slab is horizontally arranged and has a lower embedded fastener at one end adjacent to the building facade, the lower embedded fastener protruding from the lower surface of the floor slab;

[0007] The lower exterior wall panel is located below the floor slab. The upper end of the lower exterior wall panel abuts against the lower surface of the floor slab. The lower exterior wall panel is provided with a lower embedded connector. One end of the lower embedded connector extends out of the lower exterior wall panel on the side away from the building facade.

[0008] The top connecting plate is flat and is connected to one end of the lower pre-embedded connector that extends out of the lower outer wall panel; and

[0009] The lower connecting angle steel has a first fixing plate and a second fixing plate arranged at right angles to each other. The first fixing plate is used to fix the lower pre-embedded fixing member, and the second fixing plate is used to fix the top connecting plate.

[0010] In one possible implementation, the lower pre-embedded connector has an external thread at one end extending from the lower outer wall panel, the top connecting plate has a connecting hole, and the lower pre-embedded connector passes through the connecting hole at one end extending from the lower outer wall panel and is threaded with a nut.

[0011] In one possible implementation, the connecting hole is an oblong hole arranged in a horizontal or vertical direction.

[0012] In one possible implementation, the lower embedded fastener includes:

[0013] The third fixing plate is flat and horizontally positioned on the floor slab, protruding from the lower surface of the floor slab; and

[0014] The fixing foot has one end connected to the third fixing plate and the other end embedded in the floor slab. There are multiple fixing feet, which are spaced apart in the horizontal plane.

[0015] In one possible implementation, the floor slab has an upper embedded fastener at one end adjacent to the building facade, the upper embedded fastener protruding from the upper surface of the floor slab; the prefabricated building exterior wall connection structure further includes:

[0016] An upper exterior wall panel is provided above the floor slab, with the lower end of the upper exterior wall panel abutting against the upper surface of the floor slab. An upper pre-embedded connector is provided inside the upper exterior wall panel, with one end of the upper pre-embedded connector extending out of the side of the upper exterior wall panel away from the building facade.

[0017] The root connecting plate is flat and is connected to one end of the upper pre-embedded connector that extends out of the upper outer wall panel; and

[0018] The upper connecting angle steel has a fourth fixing plate and a fifth fixing plate arranged at right angles to each other. The fourth fixing plate is used to fix the upper pre-embedded fixing member, and the fifth fixing plate is used to fix the root connecting plate.

[0019] In one possible implementation, both the upper and lower outer wall panels have an internal insulation sandwich layer.

[0020] In one possible implementation, both the upper and lower outer wall panels have embedded reinforcing bars. One end of the upper embedded connector, housed within the upper outer wall panel, is connected to the embedded reinforcing bars within the upper outer wall panel. The other end of the lower embedded connector, housed within the lower outer wall panel, is connected to the embedded reinforcing bars within the lower outer wall panel.

[0021] In one possible implementation, both the upper embedded connector and the lower embedded connector include:

[0022] An embedded rod, in rod shape, has one end housed within the corresponding upper or lower exterior wall panel, and the other end passing through the corresponding upper or lower exterior wall panel on the side facing away from the building facade; and

[0023] An anchor head, in the shape of a rod, is located within the corresponding upper or lower outer wall panel. The middle part of the anchor head is connected to the embedded rod, and the length direction of the anchor head is perpendicular to the length direction of the embedded rod.

[0024] In one possible implementation, multiple anchor heads are spaced apart along the length of the embedded rod.

[0025] In one possible implementation, the lower outer wall panel has a receiving groove on the side facing away from the building facade, and the top connecting plate and the second fixing plate are respectively housed in the receiving groove, the depth of the receiving groove being greater than or equal to the sum of the thicknesses of the top connecting plate and the second fixing plate.

[0026] Compared with the prior art, the beneficial effects of the prefabricated building exterior wall connection structure provided by this utility model are:

[0027] This utility model provides a prefabricated building exterior wall connection structure including a floor slab, a lower exterior wall panel, a top connecting plate, and a lower connecting angle steel. The lower surface of the floor slab has a protruding lower embedded fixing component, and the inner side of the lower exterior wall panel has a protruding lower embedded connector. The top connecting plate is fixedly connected to the lower embedded connector as a whole. When assembling the floor slab and lower exterior wall panel, the lower exterior wall is hoisted into place, and then the lower embedded fixing component and the top connecting plate are connected as a whole using the lower connecting angle steel, thus completing the assembly of the floor slab and lower exterior wall. The lower embedded connector, top connecting plate, and lower connecting angle steel are all located on the inner side of the building, away from the building facade, eliminating the need for pre-drilled holes in the lower exterior wall panel. The lower embedded connector does not protrude from the facade, resulting in better insulation and waterproofing. It also reduces the workload of repairing and sealing joints at the facade. The structure is simple, easy to construct, and performs well, meeting current construction requirements for prefabricated buildings. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0031] Figure 1 This is a schematic diagram of a prefabricated building exterior wall connection structure provided in an embodiment of this application;

[0032] Figure 2 for Figure 1 Enlarged view of part A in the middle;

[0033] Figure 3 This is a structural schematic diagram of the lower embedded connector;

[0034] Figure 4 This is a structural diagram of the top connecting plate;

[0035] Figure 5 This is a schematic diagram of the root connection plate.

[0036] Explanation of reference numerals in the attached figures:

[0037] 10. Floor slab; 11. Lower embedded fastener; 111. Third fixing plate; 112. Fixing foot; 12. Upper embedded fastener; 20. Lower exterior wall panel; 21. Lower embedded connector; 211. Embedded rod; 212. Anchor head; 22. Insulation sandwich layer; 23. Receiving groove; 30. Top connecting plate; 31. Connecting hole; 40. Lower connecting angle steel; 41. First fixing plate; 42. Second fixing plate; 50. Upper exterior wall panel; 51. Upper embedded connector; 60. Root connecting plate; 70. Upper connecting angle steel. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0040] For ease of description, spatial relative terms may be used in the text to describe the relative position or movement of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "front," "back," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure undergoes a positional flip, orientation change, or change of motion, these directional indications will change accordingly. For instance, an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0041] Please refer to the following: Figures 1 to 5 The following describes a prefabricated building exterior wall connection structure provided by an embodiment of this utility model.

[0042] Please see Figure 1 and Figure 2This utility model provides a prefabricated building exterior wall connection structure, including a floor slab 10, a lower exterior wall panel 20, a top connecting plate 30, and a lower connecting angle steel 40. The floor slab 10 is horizontally arranged, and a lower pre-embedded fixing member 11 is provided at one end adjacent to the building facade. The lower pre-embedded fixing member 11 protrudes from the lower surface of the floor slab 10. The lower exterior wall panel 20 is located below the floor slab 10, and the upper end of the lower exterior wall panel 20 abuts against the lower surface of the floor slab 10. A lower pre-embedded connecting angle steel 40 is provided inside the lower exterior wall panel 20. The lower pre-embedded connector 21 extends out of the lower outer wall panel 20 on the side away from the building facade; the top connecting plate 30 is flat and is connected to the end of the lower pre-embedded connector 21 that extends out of the lower outer wall panel 20; the lower connecting angle steel 40 has a first fixing plate 41 and a second fixing plate 42 that are arranged at right angles to each other. The first fixing plate 41 is used to fix and connect with the lower pre-embedded fixing member 11, and the second fixing plate 42 is used to fix and connect with the top connecting plate 30.

[0043] Compared with the prior art, the beneficial effects of the prefabricated building exterior wall connection structure provided by this utility model are:

[0044] The prefabricated building exterior wall connection structure provided by this utility model includes a floor slab 10, a lower exterior wall panel 20, a top connecting plate 30, and a lower connecting angle steel 40. The lower surface of the floor slab 10 is provided with a protruding lower embedded fixing member 11, and the inner side of the lower exterior wall panel 20 is provided with a protruding lower embedded connecting member 21. The top connecting plate 30 is fixedly connected to the lower embedded connecting member 21 as a whole. When assembling the floor slab 10 and the lower exterior wall panel 20, the lower exterior wall is hoisted into place, and then the lower embedded fixing member 11 and the top connecting plate 30 are connected as a whole through the lower connecting angle steel 40, thus completing the assembly of the floor slab 10 and the lower exterior wall. The lower embedded connector 21, the top connecting plate 30, and the lower connecting angle steel 40 are all located on the inside of the building, away from the building facade. There is no need to reserve holes in the lower exterior wall panel 20, and the lower embedded connector 21 will not protrude from the facade. The insulation and waterproofing effects are better, and the workload of repairing and sealing the joints of the facade is reduced. The structure is simple, the construction is convenient, and the use effect is good, which meets the current construction needs of prefabricated buildings.

[0045] This utility model optimizes the existing connection method between composite exterior wall panels and the main structure. By pre-embedding a lower pre-embedded connector 21 in the lower exterior wall panel 20, a certain insulation layer thickness can be reserved between the metal lower pre-embedded connector 21 and the building facade, effectively reducing the cold bridge effect at this location, thereby ensuring the overall insulation and waterproof performance of the composite exterior wall panel.

[0046] The floor slab 10 can be a precast component or a cast-in-place concrete component. The lower exterior wall panel 20 and the upper exterior wall panel 50 (hereinafter referred to as the upper exterior wall panel) can have the same or different structures. Depending on the needs, holes for installing windows can be provided on the lower exterior wall panel 20 and the upper exterior wall panel 50. The lower exterior wall panel 20 and the upper exterior wall panel 50 can be precast concrete components or precast lightweight concrete components, and can have internal insulation layers, waterproof layers, fireproof layers, etc.

[0047] The lower embedded fastener 11, the lower embedded connector 21, and the top connecting plate 30 can all be steel plate-shaped components used to connect with the lower embedded connector 21. The top connecting plate 30 and the second fixing plate 42, and the first fixing plate 41 and the lower embedded fastener 11 can all be welded together on-site during splicing construction.

[0048] As needed, multiple lower embedded fasteners 11 can be installed on the floor slab 10 along the extension direction of the exterior facade, and multiple lower embedded connectors 21 can also be installed on the lower exterior wall panel 20. The lower embedded fasteners 11 and lower embedded connectors 21 are connected as a whole by the top connecting plate 30 and the lower connecting angle steel 40. There are no specific restrictions on the quantity, size, and spacing of the above-mentioned parts, as long as the connection is firm. If the length of the lower embedded connector 21 extending out of the wall is too long, the excess length can be cut off.

[0049] In some possible embodiments, the lower pre-embedded connector 21 has an external thread at one end extending from the lower outer wall panel 20, and the top connecting plate 30 has a connecting hole 31. The lower pre-embedded connector 21 is inserted into the connecting hole 31 at one end extending from the lower outer wall panel 20 and is threaded with a nut. Tightening the nut can connect the lower pre-embedded connector 21 and the top connecting plate 30 into one unit.

[0050] Please see Figure 4 and Figure 5 In some possible embodiments, the connecting hole 31 is an oblong hole arranged in the horizontal or vertical direction, which can finely adjust the relative position of the pre-embedded connector 21 and the top connecting plate 30 during installation.

[0051] Please see Figure 2 In some possible embodiments, the lower embedded fastener 11 includes a third fixing plate 111 and a fixing foot 112. The third fixing plate 111 is flat and is horizontally disposed on the floor slab 10, protruding from the lower surface of the floor slab 10; one end of the fixing foot 112 is connected to the third fixing plate 111, and the other end is embedded in the floor slab 10. There are multiple fixing feet 112, which are spaced apart in the horizontal plane.

[0052] Please see Figure 1In some possible embodiments, the floor slab 10 is provided with an upper pre-embedded fastener 12 at one end adjacent to the building facade, and the upper pre-embedded fastener 12 protrudes from the upper surface of the floor slab 10; the prefabricated building exterior wall connection structure also includes an upper exterior wall panel 50, a root connecting plate 60, and an upper connecting angle steel 70. The upper exterior wall panel 50 is located above the floor slab 10, and the lower end of the upper exterior wall panel 50 abuts against the upper surface of the floor slab 10. An upper pre-embedded connector 51 is provided inside the upper exterior wall panel 50, and one end of the upper pre-embedded connector 51 extends out of the upper exterior wall panel 50 on the side away from the building facade; the root connecting plate 60 is flat and is connected to the end of the upper pre-embedded connector 51 that extends out of the upper exterior wall panel 50; the upper connecting angle steel 70 has a fourth fixing plate and a fifth fixing plate arranged at right angles to each other. The fourth fixing plate is used to fix the upper pre-embedded fastener 12, and the fifth fixing plate is used to fix the root connecting plate 60.

[0053] In this embodiment, the upper embedded fastener 12 and the lower embedded fastener 11 have the same structure, the root connecting plate 60 and the top connecting plate 30 have the same structure, the upper embedded connector 51 and the lower embedded connector 21 have the same structure, and the upper connecting angle steel 70 and the lower connecting angle steel 40 have the same structure. The difference is that the upper outer wall panel 50 is installed above the floor slab 10 and abuts against the upper surface of the floor slab 10.

[0054] Please see Figure 1 In some possible embodiments, both the upper outer wall panel 50 and the lower outer wall panel 20 have an insulation sandwich layer 22 inside. The insulation sandwich layer 22 is disposed inside the upper outer wall panel 50 or the lower outer wall panel 20 to form a sandwich. Compared with the method of placing the insulation layer on the outside, it will not fall off during later use.

[0055] In some possible embodiments, both the upper outer wall panel 50 and the lower outer wall panel 20 have pre-embedded reinforcing bars. One end of the upper pre-embedded connector 51, housed in the upper outer wall panel 50, is connected to the pre-embedded reinforcing bars in the upper outer wall panel 50. The other end of the lower pre-embedded connector 21, housed in the lower outer wall panel 20, is connected to the pre-embedded reinforcing bars in the lower outer wall panel 20. Specifically, welding connections, wire binding connections, etc., can be used.

[0056] Please see Figure 3 In some possible embodiments, both the upper embedded connector 51 and the lower embedded connector 21 include an embedded rod 211 and an anchor head 212. The embedded rod 211 is rod-shaped, with one end of the embedded rod 211 housed within the corresponding upper outer wall panel 50 or lower outer wall panel 20, and the other end of the embedded rod 211 passing through the side of the corresponding upper outer wall panel 50 or lower outer wall panel 20 away from the building facade. The anchor head 212 is rod-shaped and is located within the corresponding upper outer wall panel 50 or lower outer wall panel 20. The middle part of the anchor head 212 is connected to the embedded rod 211, and the length direction of the anchor head 212 is perpendicular to the length direction of the embedded rod 211, which can improve the connection strength.

[0057] Please see Figure 3 In some possible embodiments, multiple anchor heads 212 are spaced apart along the length of the pre-embedded rod 211, and the multiple anchor heads 212 are not parallel to each other, which can improve the anchoring force.

[0058] Please see Figure 2 In some possible embodiments, the lower outer wall panel 20 has a receiving groove 23 on the side away from the building facade, and the top connecting plate 30 and the second fixing plate 42 are respectively housed in the receiving groove 23. The depth of the receiving groove 23 is greater than or equal to the sum of the thicknesses of the top connecting plate 30 and the second fixing plate 42, so that the wall surface is flush.

[0059] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0060] The above description describes specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A prefabricated building exterior wall connection structure, characterized in that, include: Floor slab (10), the floor slab (10) is horizontally arranged and has a lower pre-embedded fastener (11) at one end adjacent to the building facade, the lower pre-embedded fastener (11) protruding from the lower surface of the floor slab (10); The lower exterior wall panel (20) is located below the floor slab (10). The upper end of the lower exterior wall panel (20) abuts against the lower surface of the floor slab (10). The lower exterior wall panel (20) is provided with a lower embedded connector (21). One end of the lower embedded connector (21) extends out of the lower exterior wall panel (20) on the side away from the building facade. The top connecting plate (30) is flat and is connected to one end of the lower pre-embedded connector (21) that extends out of the lower outer wall panel (20); and The lower connecting angle steel (40) has a first fixing plate (41) and a second fixing plate (42) arranged at right angles to each other. The first fixing plate (41) is used to fix the lower pre-embedded fixing member (11), and the second fixing plate (42) is used to fix the top connecting plate (30).

2. The prefabricated building exterior wall connection structure according to claim 1, characterized in that, The lower pre-embedded connector (21) has an external thread at one end extending from the lower outer wall panel (20), and the top connecting plate (30) has a connecting hole (31). The lower pre-embedded connector (21) extends from the lower outer wall panel (20) through the connecting hole (31) and is threaded with a nut.

3. The prefabricated building exterior wall connection structure according to claim 2, characterized in that, The connecting hole (31) is an oblong hole arranged in the horizontal or vertical direction.

4. The prefabricated building exterior wall connection structure according to claim 1, characterized in that, The lower embedded fastener (11) includes: The third fixing plate (111) is flat and is horizontally disposed on the floor slab (10), protruding from the lower surface of the floor slab (10); and The fixing foot (112) is connected at one end to the third fixing plate (111) and the other end is embedded in the floor slab (10). There are multiple fixing feet (112), and the multiple fixing feet (112) are spaced apart in the horizontal plane.

5. The prefabricated building exterior wall connection structure according to claim 1, characterized in that, The floor slab (10) is provided with an upper embedded fastener (12) at one end adjacent to the building facade, and the upper embedded fastener (12) protrudes from the upper surface of the floor slab (10); The prefabricated building exterior wall connection structure also includes: The upper exterior wall panel (50) is located above the floor slab (10). The lower end of the upper exterior wall panel (50) abuts against the upper surface of the floor slab (10). An upper pre-embedded connector (51) is provided in the upper exterior wall panel (50). One end of the upper pre-embedded connector (51) extends out of the upper exterior wall panel (50) on the side away from the building facade. The root connecting plate (60) is flat and is connected to one end of the upper pre-embedded connector (51) that extends out of the upper outer wall panel (50); and The upper connecting angle steel (70) has a fourth fixing plate and a fifth fixing plate arranged at right angles to each other. The fourth fixing plate is used to fix the upper pre-embedded fixing member (12), and the fifth fixing plate is used to fix the root connecting plate (60).

6. The prefabricated building exterior wall connection structure according to claim 5, characterized in that, Both the upper outer wall panel (50) and the lower outer wall panel (20) have an internal thermal insulation sandwich layer (22).

7. A prefabricated building exterior wall connection structure according to claim 5, characterized in that, Both the upper outer wall panel (50) and the lower outer wall panel (20) have embedded steel bars. One end of the upper embedded connector (51) is housed in the upper outer wall panel (50) and connected to the embedded steel bars in the upper outer wall panel (50). One end of the lower embedded connector (21) is housed in the lower outer wall panel (20) and connected to the embedded steel bars in the lower outer wall panel (20).

8. A prefabricated building exterior wall connection structure according to claim 5, characterized in that, Both the upper embedded connector (51) and the lower embedded connector (21) include: An embedded rod (211) is rod-shaped, one end of which is housed within the corresponding upper outer wall panel (50) or lower outer wall panel (20), and the other end of which passes through the corresponding upper outer wall panel (50) or lower outer wall panel (20) on the side facing away from the building facade; and Anchor head (212) is rod-shaped and is located in the corresponding upper outer wall panel (50) or lower outer wall panel (20). The middle part of the anchor head (212) is connected to the embedded rod (211). The length direction of the anchor head (212) is perpendicular to the length direction of the embedded rod (211).

9. A prefabricated building exterior wall connection structure according to claim 8, characterized in that, The anchor head (212) is provided in multiple intervals along the length direction of the pre-embedded rod (211).

10. A prefabricated building exterior wall connection structure according to claim 1, characterized in that, The lower outer wall panel (20) has a receiving groove (23) on the side away from the building facade. The top connecting plate (30) and the second fixing plate (42) are respectively housed in the receiving groove (23). The depth of the receiving groove (23) is greater than or equal to the sum of the thicknesses of the top connecting plate (30) and the second fixing plate (42).

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