Hoisting mechanism for construction of super-thick prestressed laminated slab

Abstract

The invention belongs to the technical field of building construction, and discloses a hoisting mechanism for construction of a super-thick prestressed laminated slab, which comprises a main cable and two groups of transverse plates, a group of lifting hook mechanisms are movably mounted on the transverse plates, and the hoisting mechanism further comprises positioning components which are respectively mounted on the opposite sides of the two groups of transverse plates and are used for positioning the distance between the transverse plates and the edge of the prestressed laminated slab. According to the scheme, the transverse plate is placed on the steel truss of the prestressed laminated slab, the baffle is rotated, the piston rod is pulled, and after the side, facing the piston rod, of the baffle makes contact with the edge of the prestressed laminated slab, the lifting hook mechanism is hung on the steel truss; at the moment, an operator only needs to rotate the baffles on the operator downwards and make contact with the edge of the prestressed laminated slab, the group of transverse slabs can be positioned, the group of transverse slabs and the previous group of transverse slabs are placed at the two ends of the transverse slabs in the symmetrical direction, and the situation that in the hoisting process of the prestressed laminated slab, due to the fact that the positions of all hoisting points are asymmetric is avoided.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, specifically a hoisting mechanism for the construction of ultra-thick prestressed composite slabs. Background Technology

[0002] Ultra-thick prestressed composite slabs are a type of composite component widely used in modern building floor slab construction. They consist of a precast concrete ribbed slab as the base, with pre-drilled holes in the ribs into which transverse non-prestressed reinforcing bars are inserted. A composite layer of concrete is then poured on-site to ultimately form a biaxially oriented floor slab that bears the load collectively. During construction, the prestressed composite slabs are first hoisted one by one to their designed positions, then installed and arranged according to the drawings, and finally, a post-cast concrete layer is poured to form a monolithic floor structure.

[0003] When hoisting prestressed composite slabs, operators typically use four sets of hooks to attach to the truss section above the slab. To ensure the balance of the slab during hoisting, operators must first symmetrically hook the four sets of hooks to the truss reinforcement nodes inside the slab to ensure the slab is level when lifted. However, this method generally relies on the operator's experience, visually estimating the approximate positions of each lifting point. Due to the large size of the slab, relying solely on experience and visual estimation can easily lead to lifting point misalignment. Furthermore, the symmetrical center of the lifting points is difficult to accurately locate when installing the hooks, resulting in problems such as slab tilting and swaying during hoisting. Slab tilting also makes it difficult for subsequent tilted slabs to be accurately placed in the intended installation position, affecting construction efficiency. Therefore, a hoisting mechanism for ultra-thick prestressed composite slab construction has been proposed to solve these problems. Summary of the Invention

[0004] To address the problems mentioned in the background art, the present invention provides a hoisting mechanism for the construction of ultra-thick prestressed composite slabs, which solves the problem of slab tilting or swaying caused by the asymmetry between the positions of various hoisting points during the hoisting process.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a hoisting mechanism for the construction of ultra-thick prestressed composite slabs, comprising a main cable and two sets of horizontal plates, wherein a set of hook mechanisms is movably installed on the horizontal plates, and further comprising: positioning components installed on opposite sides of the two sets of horizontal plates for positioning the distance between the horizontal plates and the edge of the prestressed composite slab; the positioning components include a sleeve hinged to the horizontal plates, wherein a piston rod is movably sleeved inside the sleeve, one end of the piston rod can extend to the outside of the sleeve and is hinged to a baffle through a spring, wherein initially the baffle is parallel to the sleeve due to the spring force; One of the piston rods has an outer periphery that forms a cavity with the sleeve cavity, and the sleeve has an air hole at its tail. The diameter of the piston end of the other piston rod is smaller than that of the piston end of the first piston rod, and the piston end of the piston rod can form cavity two with the cavity of the sleeve, and the head of the sleeve is provided with air hole two. The sleeve is equipped with an oil passage pipe that is connected to the cavity, and the other end of the oil passage pipe is connected to the cavity on another sleeve.

[0006] Preferably, when the positioning component rotates downward, the height of its bottom end can be lower than the height of the bottom of the hook mechanism.

[0007] Preferably, the hook mechanism includes a set of rack and pinion sliders slidably mounted on the horizontal plate, with a hook body and a sling respectively mounted at the bottom and top of the rack and pinion sliders, and the hook body can extend to the bottom of the horizontal plate, and the top of the sling can be fixedly connected to the bottom of the main cable.

[0008] Preferably, a gear is rotatably connected to the middle of the horizontal plate; the rack portion of the two sets of rack sliders can mesh with the outer periphery of the gear, so that the two sets of rack sliders on the same horizontal plate can move synchronously in opposite directions or towards each other.

[0009] Preferably, the end of the hook body is provided with a retaining groove; the bottom of the rack slider is hinged with an elastic stop bar, and a spring push rod that can pass through the elastic stop bar in the axial direction is movably sleeved inside the elastic stop bar. In the initial state, the bottom end of the spring push rod is outside the retaining groove. A connecting pressure plate is rotatably connected to the rack slider, and the bottom end of the sling is connected to the rack slider through the connecting pressure plate; The connecting pressure plate and the elastic stop rod are located on both sides of the axis of the connecting pressure plate, and the top of the spring push rod abuts against the bottom of the connecting pressure plate. When the spring push rod moves downward, its bottom end can be inserted into the stop groove.

[0010] Preferably, the horizontal plate has a plurality of limiting groove groups, each group of limiting grooves including a plurality of limiting grooves; a spline shaft located below the sling is fixedly connected to the connecting pressure plate, the two ends of the spline shaft can extend into the rack slider and slide within the rack slider, the part of the spline shaft located within the rack slider is a one-way locking pin, and the one-way locking pin can engage with the limiting groove when it moves upward.

[0011] Preferably, the bottom end of the sling is a column and is fixedly connected to the top of the connecting pressure plate, and an annular groove is provided on the column at the bottom end of the sling; A long plate is provided above the horizontal plate. A set of straight slots are opened on the long plate. The straight slots are fitted around the outer periphery of the annular groove. The thickness of the long plate is less than the height of the annular groove. A square hole is opened in the middle of the long plate. Initially, the outer periphery of the sleeve overlaps with the bottom of the square hole.

[0012] Preferably, a set of limiting columns are fixedly connected to the long plate in a symmetrical direction, and the limiting columns penetrate the horizontal plate vertically and are movably connected to the horizontal plate.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The above solution involves placing the horizontal plate on the steel truss of the prestressed composite slab. By rotating the baffle and pulling the piston rod, the hook mechanism is hung on the steel truss when the side of the baffle facing the piston rod contacts the edge of the prestressed composite slab. At the same time, pulling the piston rod will cause the hydraulic oil in cavity one to be input into cavity two in another sleeve through the oil pipeline, and push the piston rod inside to extend synchronously. At this time, the operator only needs to rotate the baffle on it downward and contact it with the edge of the prestressed composite slab to position the group of horizontal plates and place them symmetrically at both ends of the horizontal plate with the previous group of horizontal plates. This avoids the situation where the prestressed composite slab is asymmetrical between the positions of each lifting point during the hoisting process. The above scheme involves moving two sets of rack and pinion sliders towards each other to the bottom of the steel truss. The steel truss will first push the elastic stop bar to rotate and move past the elastic stop bar into the hook body. During the hoisting process, the sling will first drive the connecting pressure plate to rotate around the axis. At this time, the bottom of the other end of the connecting pressure plate will squeeze the spring top rod downward and make its bottom end lock into the retaining groove. At this time, the steel truss part is between the hook body and the elastic stop bar, which can prevent the steel truss from falling off the hook body during hoisting or lowering. When the hoisting is completed or before hoisting, due to the spring force on the spring top rod, the elastic stop bar is in the state of being disengaged from the retaining groove. At this time, it is convenient for the operator to disassemble the hook body or readjust the hook body's attachment position. In the above scheme, as the connecting pressure plate is rotated upward by the sling, the long plate will be driven upward by the limiting column, thereby causing the square hole to move upward and the sleeve to rotate upward, thus causing the baffle to disengage from the edge of the prestressed composite slab. Subsequently, the baffle is reset under the action of the spring force, which facilitates hoisting and subsequent installation of the prestressed composite slab. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a partial frontal cross-sectional view of the present invention; Figure 3 This is a schematic diagram of the positioning component of the present invention; Figure 4 This is a front cross-sectional view of the positioning component of the present invention; Figure 5 This is a schematic cross-sectional view of the side of the horizontal plate of the present invention; Figure 6 for Figure 5Enlarged view of point A in the middle; Figure 7 This is a partial cross-sectional view of the horizontal plate of the present invention; Figure 8 This is a schematic diagram of the structure of the gear in this invention; Figure 9 This is a schematic diagram of the structure of the long plate component of the present invention.

[0015] In the diagram: 1. Horizontal plate; 11. Limiting groove; 2. Hook mechanism; 21. Rack and pinion slider; 211. Gear; 212. Connecting pressure plate; 213. Splined shaft; 22. Hook body; 221. Stop groove; 23. Lifting cable; 231. Annular groove; 3. Positioning assembly; 31. Sleeve; 32. Piston rod; 321. Cavity 1; 322. Air hole 1; 323. Cavity 2; 324. Air hole 2; 33. Baffle; 34. Oil passage; 4. Elastic stop bar; 41. Spring push rod; 5. Long plate; 51. Straight groove; 52. Limiting column; 53. Square hole; 6. Main cable. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figures 1 to 9 As shown, the present invention provides a hoisting mechanism for the construction of ultra-thick prestressed composite slabs, including a main cable 6 and two sets of horizontal plates 1, and a set of hook mechanisms 2 are movably installed on the horizontal plates 1. It also includes: positioning components 3 installed on opposite sides of the two sets of horizontal plates 1 to position the distance between the horizontal plates 1 and the edge of the prestressed composite slab; the positioning components 3 include a sleeve 31 hinged to the horizontal plates 1, a piston rod 32 movably sleeved inside the sleeve 31, one end of the piston rod 32 can extend to the outside of the sleeve 31 and is hinged to a baffle 33 by a spring, and initially the baffle 33 is parallel to the sleeve 31 due to the spring force; One of the piston rods 32 has an outer periphery that forms a cavity 321 with the cavity of the sleeve 31, and the sleeve 31 has an air hole 322 at its tail. The diameter of the piston end of the other piston rod 32 is smaller than that of the piston end of the first piston rod 32, and the piston end of the piston rod 32 can form a cavity 323 with the cavity of the sleeve 31, and the head of the sleeve 31 is provided with an air hole 324; an oil passage pipe 34 connected to the cavity 321 is installed on the sleeve 31, and the other end of the oil passage pipe 34 is connected to the cavity 323 on the other sleeve 31; when the positioning assembly 3 rotates downward, the height of its bottom end can be lower than the height of the bottom of the hook mechanism 2; The hook mechanism 2 includes a set of rack and pinion sliders 21 slidably mounted on the horizontal plate 1. The bottom and top of the rack and pinion sliders 21 are respectively equipped with hook bodies 22 and slings 23, and the hook bodies 22 can extend to the bottom of the horizontal plate 1. The top of the slings 23 can be fixedly connected to the bottom of the main cable 6. A gear 211 is rotatably connected to the middle of the horizontal plate 1. The rack parts of the two sets of rack and pinion sliders 21 can mesh with the outer periphery of the gear 211, so that the two sets of rack and pinion sliders 21 on the same horizontal plate 1 can move synchronously in opposite directions or towards each other. Using the above scheme, by placing the horizontal plate 1 on the steel truss of the prestressed composite slab, rotating the baffle 33 and pulling the piston rod 32, when the side of the baffle 33 facing the piston rod 32 contacts the edge of the prestressed composite slab, the hook mechanism 2 is hung on the steel truss. At the same time, pulling the piston rod 32 will cause the hydraulic oil in the cavity 1 321 to be input into the cavity 2 323 in another sleeve 31 through the oil pipe 34, and push the piston rod 32 inside to extend synchronously. At this time, the operator only needs to rotate the baffle 33 on it downward and contact it with the edge of the prestressed composite slab to position the group of horizontal plates 1 and place it symmetrically at both ends of the horizontal plate 1 with the previous group of horizontal plates 1, thus avoiding the asymmetry between the positions of the various lifting points during the hoisting of the prestressed composite slab. After positioning, the operator can push the rack slider 21 and drive it through the gear 211 to make the two sets of rack sliders 21 on the horizontal plate 1 move towards each other or away from each other. When the rack sliders 21 move towards each other, they can drive the two sets of hook bodies 22 to move towards each other to the bottom of the corresponding prestressed composite steel truss section. When the main cable 6 is hung under the steel truss through the sling 23, rack slider 21 and hook body 22, and at this time the two sets of hook bodies 22 have a tendency to move towards each other under the tension of the sling 23, the hoisting process can be made more stable.

[0018] like Figure 2 , Figure 5 and Figure 6 As shown, a retaining groove 221 is provided at the end of the hook body 22; an elastic stop bar 4 is hinged to the bottom of the rack slider 21, and a spring push bar 41 that can pass through the elastic stop bar 4 in the axial direction is movably sleeved inside the elastic stop bar 4. In the initial state, the bottom end of the spring push bar 41 is outside the retaining groove 221; a connecting pressure plate 212 is rotatably connected to the rack slider 21, and the bottom end of the sling 23 is connected to the rack slider 21 through the connecting pressure plate 212; The connecting pressure plate 212 and the elastic stop bar 4 are located on both sides of the axis of the connecting pressure plate 212, and the top of the spring push rod 41 abuts against the bottom of the connecting pressure plate 212. When the spring push rod 41 moves downward, its bottom end can be inserted into the stop groove 221. Using the above scheme, when the two sets of rack and pinion sliders 21 move towards each other to the bottom of the steel truss, the steel truss will first push the elastic stop bar 4 to rotate and move past the elastic stop bar 4 into the hook body 22. During the hoisting process, the sling 23 will first drive the connecting pressure plate 212 to rotate around the axis. At this time, the bottom of the other end of the connecting pressure plate 212 will squeeze the spring top rod 41 downward and make its bottom end stuck in the stop groove 221. At this time, the steel truss part is between the hook body 22 and the elastic stop bar 4, which can prevent the steel truss from falling off the hook body 22 during the hoisting or lowering process. When the hoisting is completed or before the hoisting is completed, due to the spring force on the spring top rod 41, the elastic stop rod 4 is in the state of being disengaged from the stop groove 221. At this time, it is convenient for the operator to disassemble the hook body 22 or readjust the hook body 22's attachment position.

[0019] like Figures 5-7 As shown, the horizontal plate 1 has several sets of limiting grooves, and each set of limiting grooves includes several limiting grooves 11. A spline shaft 213 located below the sling 23 is fixedly connected to the connecting pressure plate 212. Both ends of the spline shaft 213 can extend into the rack slider 21 and slide within the rack slider 21. The part of the spline shaft 213 located within the rack slider 21 is a one-way locking pin, and the one-way locking pin can be engaged in the limiting groove 11 when it moves upward. Using the above scheme, when the hook body 22 hooks the steel truss and lifts it up, the connecting pressure plate 212 will rotate around the axis, and one end of the spline shaft 213 will tilt upward. At this time, the end of the spline shaft 213 will slide in the rack slider 21, and the one-way locking pin at its top will be locked into the limiting groove 11. At this time, the relative position of the rack slider 21 and the horizontal plate 1 is locked, which further improves the stability of the hook body 22 during the lifting process.

[0020] like Figure 2 and Figures 6-9 As shown, the bottom end of the sling 23 is a column and is fixedly connected to the top of the connecting pressure plate 212. An annular groove 231 is provided on the column at the bottom end of the sling 23. A long plate 5 is provided above the horizontal plate 1. A set of straight slots 51 are provided on the long plate 5. The straight slots 51 are fitted around the outer periphery of the annular groove 231. The thickness of the long plate 5 is less than the height of the annular groove 231. A square hole 53 is provided in the middle of the long plate 5. Initially, the outer periphery of the sleeve 31 overlaps with the bottom of the square hole 53. A set of limiting columns 52 are fixedly connected to the long plate 5 in a symmetrical direction. The limiting columns 52 penetrate the horizontal plate 1 vertically and are movably connected to the horizontal plate 1. Using the above scheme, as the connecting pressure plate 212 is rotated upward by the sling 23, the long plate 5 will be driven upward by the limiting column 52, thereby causing the square hole 53 to move upward and the sleeve 31 to rotate upward, thereby causing the baffle 33 to disengage from the edge of the prestressed composite slab. Then the baffle 33 will be reset under the action of the spring force, which facilitates hoisting and subsequent installation of the prestressed composite slab.

[0021] Working principle and usage process of this invention: During positioning, the operator first places the horizontal plate 1 on the steel truss of the prestressed composite slab. Then, by rotating the baffle 33 and pulling the piston rod 32, when the side of the baffle 33 facing the piston rod 32 contacts the edge of the prestressed composite slab, the hook mechanism 2 is hung on the steel truss. At the same time, when the piston rod 32 is pulled, the hydraulic oil in the first cavity 321 will be input into the second cavity 323 in another sleeve 31 through the oil pipe 34, and push the piston rod 32 inside to extend synchronously. At this time, the operator only needs to rotate the baffle 33 on it downward and contact it with the edge of the prestressed composite slab to position the horizontal plate 1 and place it symmetrically at both ends of the horizontal plate 1 with the previous horizontal plate 1, which is convenient for subsequent hoisting. After positioning, the operator can push the rack slider 21 and drive it through the gear 211 to make the two sets of rack sliders 21 on the horizontal plate 1 move towards each other or away from each other. When the rack sliders 21 move towards each other, they can drive the two sets of hook bodies 22 to move towards each other to the bottom of the corresponding prestressed composite steel truss part. When the main cable 6 is hung under the steel truss through the sling 23, rack slider 21 and hook body 22, and at this time the two sets of hook bodies 22 have a tendency to move towards each other under the tension of the sling 23, the hoisting process can be more stable. When the two sets of rack and pinion sliders 21 move towards each other to the bottom of the steel truss, the steel truss will first push the elastic stop bar 4 to rotate and move past the elastic stop bar 4 into the hook body 22. During the hoisting process, the sling 23 will first drive the connecting pressure plate 212 to rotate around the axis. At this time, the bottom of the other end of the connecting pressure plate 212 will squeeze the spring top rod 41 downward and make its bottom end stuck in the retaining groove 221. At this time, the steel truss part is between the hook body 22 and the elastic stop bar 4, which can prevent the steel truss from falling off the hook body 22 during hoisting or lowering. When the hoisting is completed or before hoisting, due to the spring force on the spring top rod 41, the elastic stop bar 4 is in the state of being disengaged from the retaining groove 221. At this time, it is convenient for the operator to disassemble the hook body 22 or readjust the hook body 22's attachment position. During the upward rotation of the connecting pressure plate 212 driven by the sling 23, the long plate 5 will be driven upward by the limiting column 52, thereby causing the square hole 53 to move upward and the sleeve 31 to rotate upward, thereby causing the baffle 33 to disengage from the edge of the prestressed composite slab. Subsequently, the baffle 33 will be reset under the action of the spring force, which facilitates hoisting and subsequent installation of the prestressed composite slab.

[0022] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0023] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A hoisting mechanism for the construction of an ultra-thick prestressed composite slab, comprising a main cable (6) and two groups of cross plates (1), and a group of hook mechanisms (2) movably installed on the cross plates (1), characterized in that, Also include: Respectively installed on the two groups of transverse plate (1) opposite side for positioning transverse plate (1) and prestressed composite plate edge distance positioning assembly (3); The positioning assembly (3) includes a sleeve piece (31) hinged to the transverse plate (1), a piston rod (32) movably sleeved in the sleeve piece (31), one end of the piston rod (32) can extend to the outside of the sleeve piece (31) and is hinged with a baffle (33) through a spring, the baffle (33) is parallel to the sleeve piece (31) at the beginning; One of the piston rod (32) and the sleeve piece (31) cavity forms cavity one (321), and the sleeve piece (31) tail is provided with air hole one (322); The diameter of the piston end of the other piston rod (32) is smaller than that of the piston end of the previous piston rod (32), and the piston end of the piston rod (32) can form cavity two (323) with the cavity of the sleeve piece (31), and the sleeve piece (31) head is provided with air hole two (324); The sleeve piece (31) is provided with an oil channel (34) in communication with the cavity one (321), and the other end of the oil channel (34) is in communication with the cavity two (323) of the other sleeve piece (31).

2. The hoisting mechanism for super-thick prestressed composite slab construction according to claim 1, characterized in that: When the positioning assembly (3) rotates downward, the height of the bottom end can be lower than the height of the bottom of the hook mechanism (2).

3. The hoisting mechanism for super-thick prestressed composite slab construction according to claim 1, characterized in that: The hook mechanism (2) includes a group of rack sliders (21) slidingly installed on the transverse plate (1), the bottom and top of the rack slider (21) are respectively provided with a hook body (22) and a sling (23), and the hook body (22) can extend below the transverse plate (1), and the top end of the sling (23) can be fixedly connected with the bottom of the main cable (6).

4. The hoisting mechanism for super-thick prestressed composite slab construction according to claim 3, characterized in that: The middle part of the transverse plate (1) is rotatably connected with a gear (211); The rack part of the two groups of rack sliders (21) can engage with the outer periphery of the gear (211), so that the two groups of rack sliders (21) on the same transverse plate (1) can move synchronously away from or towards each other.

5. The hoisting mechanism for super-thick prestressed composite slab construction according to claim 4, characterized in that: The end of the hook body (22) is provided with a blocking groove (221); The bottom of the rack slider (21) is hinged with an elastic stop rod (4), the elastic stop rod (4) is movably sleeved with a spring push rod (41) which can penetrate the elastic stop rod (4) in the axial direction, and the bottom end of the spring push rod (41) is outside the blocking groove (221) in the initial state; The rack slider (21) is rotatably connected with a connecting pressing plate (212), and the bottom end of the sling (23) is connected with the rack slider (21) through the connecting pressing plate (212); The connecting pressing plate (212) and the elastic stop rod (4) are respectively located on both sides of the axis of the connecting pressing plate (212), and the top of the spring push rod (41) abuts against the bottom of the connecting pressing plate (212), and the bottom end of the spring push rod (41) can be clamped into the blocking groove (221) when it goes down.

6. The hoisting mechanism for super-thick prestressed composite slab construction according to claim 5, characterized in that: A plurality of limiting groove groups are formed on the transverse plate (1), each limiting groove group includes a plurality of limiting grooves (11). The connecting pressing plate (212) is fixedly connected with a spline shaft (213) below the sling (23), two ends of the spline shaft (213) can extend into the rack slider (21) and can slide in the rack slider (21), the part of the spline shaft (213) in the rack slider (21) is a one-way catch, and the one-way catch can be clamped into the limiting groove (11) when ascending.

7. The hoisting mechanism for super-thick prestressed composite slab construction according to claim 5, characterized in that: The bottom end of the sling (23) is a column and is fixedly connected with the top of the connecting pressing plate (212), and an annular groove (231) is formed in the column at the bottom end of the sling (23). A long plate piece (5) is arranged above the horizontal plate (1), a group of straight slots (51) are formed in the long plate piece (5), the straight slots (51) are sleeved outside the annular groove (231), the thickness of the long plate piece (5) is less than the height of the annular groove (231), a square hole (53) is formed in the middle of the long plate piece (5), and the outer periphery of the sleeve piece (31) is initially overlapped with the bottom of the square hole (53).

8. The hoisting mechanism for super-thick prestressed composite slab construction according to claim 7, characterized in that: A group of limiting column bodies (52) are fixedly connected in a symmetrical direction on the long plate piece (5), the limiting column bodies (52) vertically penetrate the horizontal plate (1) and are movably connected with the horizontal plate (1).

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