A tunnel broken rock support device

Abstract

The present invention discloses a tunnel broken rock support device, and relates to the technical field of tunnel construction. The present invention comprises an arch frame, and a protective net arranged on the outside of the arch frame; the protective net is woven and connected by steel wire A and a "cross"-shaped connecting block A to form a grid structure; the steel wire A comprises a steel wire body, and limit plates arranged at both ends of the steel wire body; the "cross"-shaped connecting block A comprises a base plate A, a protrusion A is arranged on the peripheral side of the base plate A, an external threaded pipe is arranged on the protrusion A, the external threaded pipe is provided with an opening along its length direction, and a bolt is threadedly connected to the outer side of the external threaded pipe. The present invention uses an arch frame and a protective net arranged on the outside of the arch frame, and utilizes the setting of the protective net to increase the protection range as much as possible while keeping the arch frame unchanged, thereby solving the problem that the existing device has a small support range in actual use and only realizes protection of a small range.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a tunnel broken rock support device. Background Art

[0002] Tunnels are engineering structures buried in the ground. They are a form of human use of underground space. Tunnels can be divided into traffic tunnels, hydraulic tunnels, municipal tunnels, and mining tunnels. The structure of a tunnel consists of two parts: the main building and ancillary equipment. The main building consists of a tunnel body and a tunnel portal. The ancillary equipment includes a car shelter, fire-fighting facilities, emergency communications, and drainage facilities. Long tunnels also have special ventilation and lighting equipment. According to the geological conditions of the tunnel: earth tunnels and stone tunnels, there may be the possibility of rock collapse during the construction of the tunnel, which poses certain safety hazards to construction workers and requires relevant protective devices for safety protection.

[0003] For example, CN113653518A discloses a tunnel construction protection device, including a base and a support frame arranged on the base, a moving mechanism is arranged at the bottom of the base, the moving mechanism includes a roller assembly, the roller assembly is arranged on a support rod at the bottom of the support frame, a support seat is slidably connected to the support rod, and a driving mechanism is connected to the base, the driving mechanism can drive the support seat to move up and down along the support rod and has a storage state located above the roller assembly and a support state located below the roller assembly; an arc-shaped top frame is arranged on the top of the support frame, and an arc-shaped telescopic frame is arranged on opposite sides of the arc-shaped top frame; a top frame support assembly is arranged on the support frame, and is used to support the arc-shaped top frame and / or the arc-shaped telescopic frame; however, the device has a small supporting range in actual use and can only achieve protection for a small range. Summary of the invention

[0004] The object of the present invention is to provide a tunnel rock crushing support device, which uses an arch frame and a protective net arranged on the outside of the arch frame to increase the protection range as much as possible while keeping the arch frame unchanged, thereby solving the problem that the existing device has a small support range in actual use and can only achieve protection for a small range.

[0005] To solve the above technical problems, the present invention is achieved through the following technical solutions:

[0006] The present invention discloses a tunnel rock crushing support device, comprising an arch frame and a protective net arranged on the outside of the arch frame; the protective net is woven and connected by steel wires A and a "cross"-shaped connecting block A to form a grid structure; the steel wires A comprise a steel wire body and limit plates arranged at both ends of the steel wire body; the "cross"-shaped connecting block A comprises a base plate A, a protrusion A is arranged on the circumference of the base plate A, an external threaded pipe is arranged on the protrusion A, the external threaded pipe is provided with an opening along its length direction, and bolts are threadedly connected to the outer side of the external threaded pipe; an inverted ""-shaped side plate is respectively arranged on the edge side of the protrusion located on both sides of the external threaded pipe, and the two side plates and the protrusion form a channel A for accommodating the limit plate.

[0007] Furthermore, the "cross"-shaped connecting block A also includes a blocking block A fixed on the base plate and used to limit the limiting plate located in the channel A; the base plate and the blocking block A are provided with a threaded hole A and a threaded hole B in a concentric structure; a fixing bolt is penetrated through the threaded hole B, and the fixing bolt extends into the threaded hole A;

[0008] Four L-shaped positioning blocks are arranged on one side of the blocking block A, and the four L-shaped positioning blocks are respectively clamped on the four corner sides of the base plate.

[0009] Furthermore, the arch frame includes a plurality of arch frame units arranged in gaps; the arch frame unit includes two first columns located on one side, and a second column located on the other side, and the two first columns and the second column are distributed in an isosceles triangle; at least one telescopic rod is connected between the two first columns, and an arch bracket is connected between the tops of the first column and the second column; the arch bracket includes an arch bracket body, and fixing columns arranged at both ends of the arch bracket body; mounting blocks for mounting the arch bracket are arranged on the tops of the first column and the second column, and the mounting blocks are provided with sockets for inserting the fixing columns, and a locking bolt A is also arranged on one side of the mounting block.

[0010] Furthermore, the telescopic rod includes an inner sleeve and an outer sleeve which are movably connected to each other, and a locking bolt B is provided at the end of the outer sleeve; the ends of the inner sleeve and the outer sleeve are respectively connected to a fixing sleeve which is sleeved on the first column, and a locking bolt C is provided on the fixing sleeve; a vertically arranged baffle rod is also fixed on the telescopic rod located at the top, and an L-shaped mounting plate is provided on one side of the baffle rod, and a fastening bolt A is provided on the L-shaped mounting plate.

[0011] Furthermore, a protective rod is provided at the top of the arch frame; the protective rod includes a metal rod body, which is arranged in a fixing sleeve of the arch support, and a locking bolt D is provided on the fixing sleeve. A rod sleeve is rotatably provided on the fixing sleeve for the metal rod body to pass through and fix the metal rod body, and a tightening bolt E is provided on the rod sleeve.

[0012] Furthermore, a plurality of horizontally arranged cross bars are connected between two adjacent arch frame units; a vertically arranged blocking bar is also fixed on the cross bar at the top; a mounting structure for mounting the cross bar is provided on the first column and the second column; the mounting structure comprises a set of column sleeves provided on the first column or the second column, a U-shaped card plate for accommodating the cross bar is provided on the outer side of the column sleeve, an L-shaped movable plate is movably penetrated through the outermost top of the U-shaped card plate, and a threaded through hole is provided on the top of the L-shaped movable plate; a fixing bolt is provided on the end of the L-shaped movable plate, and a fixing blind hole cooperating with the fixing bolt is provided on one side of the U-shaped card plate; a fastening bolt is provided on the column sleeve;

[0013] During installation, a fixing bolt B is installed in the threaded through hole, and the fixing bolt B passes through the threaded through hole and abuts against the cross bar; and the protection bars on two adjacent arch frame units are staggered.

[0014] Furthermore, a "cross"-shaped connecting block B connected to the protective net is fixed on the first column and the second column, and the "cross"-shaped connecting block B includes a base plate B, and a protrusion B is arranged on the peripheral side of the base plate B. A groove for the entire steel wire body to pass through is opened on the upper surface of the protrusion B, and a socket is arranged at the end of the protrusion B, and a plug plate is arranged on the socket.

[0015] Furthermore, the upper surface of the protrusion B is higher than the upper surface of the substrate B; and a protrusion is provided on the side of the protrusion close to the substrate B; a mounting hole is provided on the upper surface of the substrate B, and a blocking column is installed in conjunction with the mounting hole, and a plug column inserted into the mounting hole is provided on the blocking column, and the protrusion, the blocking column, the substrate B and the protrusion B form a channel B for accommodating the limit plate.

[0016] Furthermore, it also includes a fixing frame for fixing the "cross" shaped connecting block B to the first column and / or the second column; the fixing frame includes a top plate, on which a fixing bolt C is arranged, and the surrounding side of the top plate is provided with supporting legs that abut against the four corner sides of the "cross" shaped connecting block B, and the ends of the supporting legs are provided with mounting plates, and the mounting bolts are arranged on the mounting plate.

[0017] Furthermore, a slat is provided at the end of the plug board, an L-shaped rod A is provided at both ends of the slat, or an L-shaped rod B is provided at both ends, and a protruding block is provided at the end of the L-shaped rod A to limit the L-shaped rod B; the support leg is an L-shaped structure and is clamped on the block.

[0018] The present invention has the following beneficial effects:

[0019] The present invention uses an arch frame and a protective net arranged outside the arch frame, and utilizes the setting of the protective net to increase the protection range as much as possible while keeping the arch frame unchanged, thereby solving the problem that the existing device has a small supporting range in actual use and can only achieve protection for a small range.

[0020] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 Schematic diagram of the arch frame unit structure of the present invention Figure 1 ;

[0023] Figure 2 for Figure 1 A partial enlarged view of the middle part;

[0024] Figure 3 Schematic diagram of the arch frame unit structure of the present invention Figure 2 ;

[0025] Figure 4 for Figure 3 A partial enlarged view of point B in the middle;

[0026] Figure 5 This is a schematic diagram of the structure of the protective net of the present invention;

[0027] Figure 6 The structure of the "cross" shaped connection block A of the present invention is shown in FIG. Figure 1 ;

[0028] Figure 7 The structure of the "cross" shaped connection block A of the present invention is shown in FIG. Figure 2 ;

[0029] Figure 8 It is a schematic diagram of the steel wire structure of the present invention;

[0030] Fig. 9 This is a schematic diagram of the arch frame structure of the present invention;

[0031] Fig.10 This is a schematic diagram of the structure of the protection rod of the present invention;

[0032] Fig.11 It is a schematic diagram of the installation structure of the present invention;

[0033] Fig.12 This is a structural schematic diagram of a "cross" shaped connecting block B of the present invention;

[0034] Fig.13 For the present invention Fig.12 A partial enlarged view of point C in the middle;

[0035] Fig.14 For the present invention Fig.12 The main view;

[0036] Fig.15 For the present invention Fig.14 sectional view of . DETAILED DESCRIPTION

[0037] like Figure 1-15 A tunnel rock support device, comprising an arch frame and a protective net arranged outside the arch frame; the protective net is woven and connected by steel wires 4 and a "cross"-shaped connecting block A2 to form a grid structure; the steel wire 4 comprises a steel wire body 40 and limit plates 41 arranged at both ends of the steel wire body 40; the "cross"-shaped connecting block A2 comprises a base plate A20, a convex portion A21 is arranged on the circumference of the base plate A20, an external threaded tube 22 is arranged on the convex portion A21, the external threaded tube 22 is provided with an opening 221 along its length direction, and the outer side surface of the external threaded tube 22 is threadedly connected with Bolt 222; an inverted ""-shaped side plate 23 is respectively arranged on the edge side of the protrusion 21 on both sides of the external threaded tube 22, and the two side plates 23 and the protrusion 21 form a channel A for accommodating the limit plate 41; in actual operation, the arch frame is first arranged and fixed according to needs; and then the protective net is laid on the outside of the arch frame; in the present invention, the "cross"-shaped connecting block A2 of the steel wire 4 is used to weave and connect the grid-like structure protective net, which is convenient for winding and laying in actual use; and because the length of a single steel wire 4 is relatively short, it is convenient to bend the protective net when in use.

[0038] like Figure 6-7 The "cross"-shaped connecting block A2 also includes a blocking block A24 fixed on the base plate 20 and used to limit the limit plate 41 located in the channel A; the base plate 20 and the blocking block A24 are provided with a threaded hole A201 and a threaded hole B in a concentric structure; a fixing bolt 25 is penetrated through the threaded hole B, and the fixing bolt 25 extends into the threaded hole A201; four L-shaped positioning blocks 26 are provided on one side of the blocking block A24, and the four L-shaped positioning blocks 26 are respectively clamped on the four corner sides of the base plate 20; the setting of the blocking block A24 is used to facilitate the limiting of the limit plate 41 located in the channel A, so as to prevent the limit plate 41 from slipping out of the channel A during use.

[0039] like Figure 1-3The arch frame includes an arch frame unit 1 with a plurality of gaps therebetween; the arch frame unit 1 includes two first columns 11 located on one side and a second column 12 located on the other side, and the two first columns 11 and the second column 12 are distributed in an isosceles triangle; at least one telescopic rod 13 is connected between the two first columns 11, and an arch bracket 14 is connected between the tops of the first column 11 and the second column 12; the arch bracket 14 includes an arch bracket body 141, and fixed columns 142 arranged at both ends of the arch bracket body 141; the tops of the first column 11 and the second column 12 are both provided with mounting blocks 15 for mounting the arch bracket 14, and the mounting blocks 15 are provided with jacks 151 for inserting the fixed columns 142, and a locking bolt A is also arranged on one side of the mounting block 15; the arrangement of the three columns ensures the stability of the basic structure of the arch frame unit 1, and facilitates the installation and placement of the arch frame unit 1 during installation.

[0040] like Figure 1-3 and 10; the telescopic rod 13 comprises an inner sleeve 131 and an outer sleeve 132 which are movably sleeved with each other, and a locking bolt B133 is arranged at the end of the outer sleeve 132; the ends of the inner sleeve 131 and the outer sleeve 132 are respectively connected with a fixing sleeve 134 sleeved on the first column 11, and a locking bolt C135 is arranged on the fixing sleeve 134; a vertically arranged blocking rod 5 is also fixed on the telescopic rod 13 located at the top, and an L-shaped mounting card plate 51 is arranged on one side of the blocking rod 5, and a fixing bolt A52 is arranged on the L-shaped mounting card plate 51; a protective rod 3 is arranged on the top of the arch frame; the protective rod 3 comprises a metal rod body 31, a fixing sleeve 32 arranged on the arch bracket 14, a locking bolt D321 is arranged on the fixing sleeve 32, and a rod sleeve 33 for the metal rod body 31 to pass through and fix the metal rod body 31 is rotatably arranged on the fixing sleeve 32, and a tightening bolt E331 is arranged on the rod sleeve 33;

[0041] like Fig. 9 and 11 ; A number of horizontally arranged cross bars 6 are connected between two adjacent arch frame units 1; a vertically arranged blocking rod 5 is also fixed on the cross bar 6 located at the top; a mounting structure for mounting the cross bar 6 is provided on the first column 11 and the second column 12; the mounting structure includes a column sleeve 61 arranged on the first column 11 or the second column 12, a U-shaped card plate 62 for accommodating the cross bar 6 is provided on the outer side of the column sleeve 61, an L-shaped movable plate 63 is movably penetrated through the outermost top of the U-shaped card plate 62, and a threaded through hole is provided on the top of the L-shaped movable plate 63; a fixing bolt 631 is provided at the end of the L-shaped movable plate 63, and a fixing blind hole matched with the fixing bolt 631 is provided on one side of the U-shaped card plate 62; a fastening bolt 611 is provided on the column sleeve 61; during installation, a fixing bolt B632 is installed at the threaded through hole, and the fixing bolt B632 passes through the threaded through hole and abuts against the cross bar 6; and the protective rods 3 on the two adjacent arch frame units 1 are staggered.

[0042] By setting a protective structure 1 composed of a protective rod 3 on the top of the arch frame, and a protective structure 2 composed of a blocking rod 5 and a cross bar 6 on both sides, basic all-round protection is achieved as a whole, and the protection effect is improved. At the same time, the installation and disassembly of the protective rod 3 and the cross bar 6 are facilitated by the setting of a fixing sleeve, an installation structure, etc.

[0043] like Figure 12-15 The first column 11 and the second column 12 are also fixed with a "cross" shaped connection block B7 connected to the protective net. The "cross" shaped connection block B7 includes a base plate B70, and a protrusion B71 is provided on the peripheral side of the base plate B70. A groove 72 for the steel wire body 40 to pass through as a whole is opened on the upper surface of the protrusion B71. A socket 711 is provided at the end of the protrusion B71. A plug plate 73 is provided on the socket 711. The upper surface of the protrusion B71 is higher than the base plate B7. 0; and a flange 74 is provided on the side of the protrusion 71 close to the substrate B70; a mounting hole 701 is provided on the upper surface of the substrate B70, and a blocking column 75 is installed in conjunction with the mounting hole 701, and a plug column 751 is provided on the blocking column 75 for inserting into the mounting hole 701, and the flange 74, the blocking column 85, the substrate B70 and the protrusion B71 form a channel B for accommodating the limit plate 41; the setting of the "cross" shaped connecting block B7 facilitates the installation of the protective net that plays a protective role.

[0044] like Figure 12-15 ; Also includes a fixing frame for fixing the "cross" shaped connecting block B7 to the first column 11 and / or the second column 12; The fixing frame includes a top plate 8, on which a fixing bolt C81 is provided, and the peripheral side of the top plate 8 is provided with a leg 82 that abuts against the four corners of the "cross" shaped connecting block B7, and a mounting plate 83 is provided at the end of the leg 82, and a mounting bolt 84 is provided on the mounting plate 83; A strip 76 is provided at the end of the plug plate 73, and an L-shaped rod body A77 is provided at both ends of the strip 76, or an L-shaped rod body B78 is provided at both ends, L The end of the L-shaped rod body A77 is provided with a protruding bump 771 that limits the L-shaped rod body B78; the support leg 82 is an L-shaped structure and is clamped on the bump 771; through the mutual cooperation between the L-shaped rod body B78 and the L-shaped rod body A77, and the coordinated setting of the support leg 82, it is convenient to limit the plug plate 73 after the plug plate 73 is inserted into the socket 711 to prevent it from slipping out; at the same time, by setting the mounting bolts 84 on the mounting plate 83, it is convenient to fix the "cross"-shaped connecting block B7 to the first column 11 and / or the second column 12.

[0045] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0046] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A tunnel broken rock support device, characterized in that: It includes an arch frame and a protective net arranged outside the arch frame; The protective net is formed by weaving and connecting steel wires (4) and "cross"-shaped connecting blocks A (2) to form a grid-like structure; the steel wires (4) include a steel wire body (40) and limit plates (41) arranged at both ends of the steel wire body (40); The "X"-shaped connecting block A (2) comprises a base plate A (20), a protrusion A (21) is arranged on the circumferential side of the base plate A (20), an external threaded tube (22) is arranged on the protrusion A (21), an opening (221) is arranged along the length direction of the external threaded tube (22), and a bolt (222) is threadedly connected to the outer side surface of the external threaded tube (22); an inverted """-shaped side plate (23) is respectively arranged on the edge side of the protrusion A (21) on both sides of the external threaded tube (22), and the two side plates (23) and the protrusion A (21) form a channel A for accommodating a limit plate (41); The "cross"-shaped connecting block A (2) further comprises a blocking block A (24) fixed on the base plate A (20) and used for limiting the position of the limiting plate (41) located in the channel A; the base plate A (20) and the blocking block A (24) are provided with a threaded hole A (201) and a threaded hole B in a concentric structure; a fixing bolt (25) is provided through the threaded hole B, and the fixing bolt (25) extends into the threaded hole A (201); Four L-shaped positioning blocks (26) are arranged on one side of the blocking block A (24), and the four L-shaped positioning blocks (26) are respectively clamped on the four corner sides of the base plate A (20); The arch frame comprises a plurality of arch frame units (1) arranged at intervals; the arch frame unit (1) comprises two first columns (11) located on one side, and a second column (12) located on the other side, the two first columns (11) and the second column (12) being distributed in an isosceles triangle; At least one telescopic rod (13) is connected between the two first columns (11); an arch support (14) is connected between the tops of the first column (11) and the second column (12); the arch support (14) comprises an arch support body (141) and fixing columns (142) arranged at both ends of the arch support body (141); Wherein, a mounting block (15) for mounting an arch support (14) is disposed at the top of each of the first column (11) and the second column (12); a socket (151) for inserting a fixing column (142) is disposed on the mounting block (15); a locking bolt A is also disposed on one side of the mounting block (15); a protective rod (3) is disposed at the top of the arch support; the protective rod (3) comprises a metal rod body (31), which is disposed on a fixing sleeve (32) of the arch support (14); a locking bolt D (321) is disposed on the fixing sleeve (32); a rod sleeve (33) for the metal rod body (31) to pass through and fix the metal rod body (31) is rotatably disposed on the fixing sleeve (32); a locking bolt E (331) is disposed on the rod sleeve (33); A plurality of horizontally arranged cross bars (6) are connected between two adjacent arch frame units (1); a vertically arranged blocking bar (5) is also fixed on the cross bar (6) located at the top; and a mounting structure for mounting the cross bar (6) is provided on the first column (11) and the second column (12); The mounting structure comprises a column sleeve (61) arranged on the first column (11) or the second column (12); a U-shaped cardboard (62) for accommodating the crossbar (6) is arranged on the outer side of the column sleeve (61); an L-shaped movable plate (63) is movably penetrated through the outermost top of the U-shaped cardboard (62); a threaded through hole is arranged on the top of the L-shaped movable plate (63); a fixing bolt (631) is arranged at the end of the L-shaped movable plate (63); a fixing blind hole cooperating with the fixing bolt (631) is arranged on one side of the U-shaped cardboard (62); a fastening bolt (611) is arranged on the column sleeve (61); During installation, a fixing bolt B (632) is installed in the threaded through hole, and the fixing bolt B (632) passes through the threaded through hole and abuts against the cross bar (6); Furthermore, the protection rods (3) on two adjacent arch frame units (1) are arranged in a staggered manner.

2. A tunnel broken rock support device according to claim 1, characterized in that: The telescopic rod (13) comprises an inner sleeve (131) and an outer sleeve (132) which are movably sleeved with each other, and a locking bolt B (133) is arranged at the end of the outer sleeve (132); the ends of the inner sleeve (131) and the outer sleeve (132) are respectively connected to a fixing sleeve (134) sleeved on the first column (11), and a locking bolt C (135) is arranged on the fixing sleeve (134); A vertically arranged blocking rod (5) is also fixed on the telescopic rod (13) at the top, an L-shaped mounting plate (51) is arranged on one side of the blocking rod (5), and a fastening bolt A (52) is arranged on the L-shaped mounting plate (51).

3. A tunnel broken rock support device according to claim 1, characterized in that: A "cross" shaped connection block B (7) connected to the protective net is also fixed on the first column (11) and the second column (12), and the "cross" shaped connection block B (7) comprises a base plate B (70), a convex portion B (71) is arranged on the peripheral side of the base plate B (70), a groove (72) for the steel wire body (40) to pass through as a whole is opened on the upper surface of the convex portion B (71), a socket (711) is arranged at the end of the convex portion B (71), and a plug plate (73) is arranged on the socket (711).

4. A tunnel broken rock support device according to claim 3, characterized in that: The upper surface of the protrusion B (71) is higher than the upper surface of the substrate B (70); and a protrusion (74) is provided on the side of the protrusion B (71) close to the substrate B (70); a mounting hole (701) is provided on the upper surface of the substrate B (70), and a blocking column (75) is installed in conjunction with the mounting hole (701), and the blocking column (75) is provided with an insert column (751) inserted into the mounting hole (701), and the protrusion (74), the blocking column (75), the substrate B (70) and the protrusion B (71) form a channel B for accommodating the limiting plate (41).

5. A tunnel broken rock support device according to claim 3 or 4, characterized in that: It also includes a fixing frame for fixing the "cross" shaped connecting block B (7) to the first column (11) and / or the second column (12); The fixing frame comprises a top plate (8), a fixing bolt C (81) is arranged on the top plate (8), a supporting leg (82) is arranged on the circumference of the top plate (8) and abuts against four corners of a "cross"-shaped connecting block B (7), a mounting plate (83) is arranged at the end of the supporting leg (82), and a mounting bolt (84) is arranged on the mounting plate (83).

6. A tunnel broken rock support device according to claim 5, characterized in that: A slat (76) is arranged at the end of the plug plate (73); an L-shaped rod A (77) is arranged at both ends of the slat (76); or an L-shaped rod B (78) is arranged at both ends; and a protruding block (771) is arranged at the end of the L-shaped rod A (77) to limit the L-shaped rod B (78); and the supporting leg (82) is of an L-shaped structure and is clamped on the protruding block (771).

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