An operating platform for welding steel structure net rack

Abstract

The present application relates to the technical fields of welded steel structure net rack, in particular to an operating platform for welded steel structure net rack, which comprises an operating table, the upper end of the operating table is connected with a positioning groove, one end of the positioning groove is provided with a limiting block, the lower end of the limiting block is connected with a spring rod A, the upper end of the operating table is provided with a welding machine, the inside of the positioning groove is provided with a movable plate, one end of the movable plate is connected with a push rod, the present application can make the supporting rod produce knocking on the steel frame when the welding machine moves after each welding, and then produce vibration on the steel frame, the knocking vibration can make the welding part produce slight plastic deformation through external force, so as to release and redistribute the stress of the stress concentration area, thereby reducing the welding residual stress and the risk of structural deformation and cracking caused by residual stress, at the same time, the knocking vibration can refine the grains inside the weld metal, which is helpful to improve the mechanical properties such as strength, toughness and ductility of the weld.

Description

Technical Field

[0001] This invention relates to the field of welded steel structure space frame technology, specifically to an operating platform for welded steel structure space frames. Background Technology

[0002] With the continuous advancement of modern construction technology, steel space frames have been widely used in various large-scale construction projects due to their excellent mechanical properties, good spatial adaptability, and beautiful shape. This has led to an increasing demand for construction technology of steel space frames and has also placed higher requirements on the operating platform during the construction process. For example, plasma welding is a high-efficiency and high-quality welding process with advantages such as concentrated energy, fast welding speed, good weld quality, and small heat-affected zone. It is particularly suitable for some parts of steel space frames that have high requirements for welding quality.

[0003] Traditional welding operation platforms can only position the steel frame to be welded. At the same time, welding generates a lot of fumes, which can affect the health of workers and cause pollution to the surrounding environment. Furthermore, there will be certain stress at the connection between the welded space frame, which may lead to structural deformation and cracking, thus affecting the subsequent use of the steel frame. Summary of the Invention

[0004] This invention causes the support rod to strike the steel frame when the welding machine moves after each weld, thereby generating vibration in the steel frame. The striking vibration can cause slight plastic deformation of the weldment through external force, promoting the release and redistribution of stress in the stress concentration area, thereby reducing welding residual stress and reducing the risk of structural deformation and cracking caused by residual stress. At the same time, the striking vibration can refine the grains inside the weld metal, which helps to improve the mechanical properties of the weld, such as strength, toughness and ductility.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an operating platform for welding steel structure space frames, comprising an operating table, two sets of positioning grooves fixedly connected to the upper surface of the operating table, a limit block provided on one side of each of the two sets of positioning grooves, a spring rod A fixedly connected to the lower end of each limit block, a welding machine provided on the upper surface of the operating table, movable plates provided inside the positioning grooves, two sets of movable plates provided inside the positioning grooves, a push rod fixedly connected to one end of each of the two sets of movable plates, the end of the push rod away from the movable plate extending through the operating table to the outside, a spring provided on the outside of the push rod, one end of the spring fixedly connected to the push rod, the other end fixedly connected to the operating table, a fixed plate connected to one end of the push rod, and an air extraction groove provided inside the operating table. An air extraction pipe is connected to the lower end of the air extraction slot. An air inlet pipe is provided on one side of the fixed plate. One end of the air inlet pipe is connected to a blower. A positioning block is fixedly connected to the upper end of the operating platform. A movable frame is movably connected inside the positioning block. A protrusion is provided at one end of the movable frame. A movable rod is connected to one side of the fixed plate. A fixed frame is fixedly connected to one end of the operating platform. A motor is fixedly connected to the upper end of the fixed frame. A threaded rod is rotatably connected to the output end of the motor. The outer side of the threaded rod is threadedly connected to a welding machine. A pulley A is fixedly connected to the end of the threaded rod away from the motor. A belt is sleeved inside the pulley A. A pulley B is sleeved at the end of the belt away from the pulley A. A bracket is movably connected to one end of the threaded rod. The other end of the bracket is movably connected to pulley B.

[0006] Preferably, two sets of sliding grooves are provided on both sides of the operating table, the welding machine is slidably connected inside the sliding grooves, and the spring rod A extends through the operating table to the lower end.

[0007] Preferably, a rack A is fixedly connected to the outer side of one set of push rods, a gear A is provided on the outer side of the suction pipe, and a rotating shaft A is fixedly connected to the side of the gear A near the suction pipe. One end of the rotating shaft A extends through the suction pipe and into the interior to connect with a valve. The gear A and the rack A are located on the same plane and mesh with each other. The suction groove is embedded in the upper surface of the operating table. One end of the suction pipe is connected to the suction groove, and the other end is connected to the exhaust fan.

[0008] Preferably, another set of push rods is fixedly connected to a rack B on the outside, and a gear B is provided on the outside of the air intake pipe. A rotating shaft B is provided at one end of the gear B near the air intake pipe. The rotating shaft B extends through the air intake pipe and into the interior to connect with a valve. The gear B rotates through the rack B. One end of the air intake pipe is connected to a hot air blower, and the other end is connected to a blower trough. The blower trough is fixedly connected to the surface of the operating table.

[0009] Preferably, the movable rod is movably connected to the center of one side of the fixed plate, and a snap-fit ​​groove is provided at the axis of the movable rod.

[0010] Preferably, a connecting rod is fixedly connected to the side of the pulley B near the fixed plate. The end of the connecting rod near the movable rod is a snap-fit ​​rod. The snap-fit ​​rod matches the snap-fit ​​groove at the center of the movable rod shaft, and the snap-fit ​​rod and the snap-fit ​​groove are located on the same plane.

[0011] Preferably, one end of the movable frame is provided with two sets of support rods, the two sets of support rods are located at the upper end of the positioning groove, the other end of the movable frame is fixedly connected with two sets of connecting plates, the protrusion is located at the center of the two sets of connecting plates, and two sets of spring rods B are fixedly connected to both sides of the protrusion, the other end of the two sets of spring rods B is fixedly connected to their respective connecting plates.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: After gear A rotates, the valve inside the exhaust pipe will be opened, so that the exhaust fan can draw air through the exhaust pipe. The exhaust pipe will quickly collect the fumes generated during welding through the exhaust groove, thereby preventing the fumes from spreading in the workshop and preventing workers from inhaling dust, thus protecting the health and safety of workers and reducing environmental pollution.

[0013] This invention automatically opens a valve when the steel frame is fixed, thereby preheating the steel frame before welding. This prevents some high-strength steels from developing hardened structures during the welding cooling process, which can lead to reduced toughness, increased brittleness, and increased susceptibility to cracking. Furthermore, proper preheating can make the metal structure of the welded joint more uniform and reduce welding defects such as porosity and slag inclusions.

[0014] This invention causes the support rod to strike the steel frame when the welding machine moves after each weld, thereby generating vibration in the steel frame. The striking vibration can cause slight plastic deformation of the weldment through external force, promoting the release and redistribution of stress in the stress concentration area, thereby reducing welding residual stress and reducing the risk of structural deformation and cracking caused by residual stress. At the same time, the striking vibration can refine the grains inside the weld metal, which helps to improve the mechanical properties of the weld, such as strength, toughness and ductility. Attached Figure Description

[0015] Figure 1 This is one of the overall structural schematic diagrams of the present invention.

[0016] Figure 2 The second schematic diagram shows the overall structure of the present invention.

[0017] Figure 3 The third schematic diagram shows the overall structure of the present invention.

[0018] Figure 4 This is one of the structural diagrams of the present invention.

[0019] Figure 5 This is a partial structural diagram of the present invention.

[0020] Figure 6 This is one of the partial structural cross-sectional views of the present invention.

[0021] Figure 7 This is a second partial structural cross-sectional view of the present invention.

[0022] Figure 8 This is an enlarged view of the structure at point A of the present invention.

[0023] Figure 9 This is an enlarged view of the structure at point B of the present invention.

[0024] In the diagram: 1. Operating table; 2. Slide groove; 3. Positioning groove; 4. Limit block; 5. Spring rod A; 6. Welding machine; 7. Movable plate; 8. Push rod; 9. Spring; 10. Rack A; 11. Gear A; 12. Suction pipe; 13. Suction groove; 14. Rack B; 15. Gear B; 16. Inlet pipe; 17. Blowing groove; 18. Positioning block; 19. Movable frame; 20. Spring rod B; 21. Protrusion; 22. Fixed plate; 23. Movable rod; 24. Fixed frame; 25. Motor; 26. Threaded rod; 27. Pulley A; 28. Belt; 29. ​​Pulley B; 30. Connecting rod. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] This invention provides an operating platform for welding steel structure space frames, including an operating table 1. Two sets of positioning grooves 3 are fixedly connected to the upper surface of the operating table 1. Each set of positioning grooves 3 has a limit block 4 on one side. A spring rod A5 is fixedly connected to the lower end of the limit block 4. A welding machine 6 is installed on the upper end of the operating table 1. Movable plates 7 are installed inside the positioning grooves 3. Two sets of movable plates 7 are installed inside the positioning grooves 3. A push rod 8 is fixedly connected to one end of each set of movable plates 7. The end of the push rod 8 away from the movable plate 7 extends through the operating table 1 to the outside. A spring 9 is installed on the outside of the push rod 8. One end of the spring 9 is fixedly connected to the push rod 8, and the other end is fixedly connected to the operating table 1. A fixed plate 22 is connected to one end of the push rod 8. An air extraction groove 13 is installed inside the operating table 1. An air extraction pipe 12 is connected to the lower end of the air extraction groove 13. The fixed plate 22... An air inlet pipe 16 is provided on the side, and one end of the air inlet pipe 16 is connected to a blower trough 17. A positioning block 18 is fixedly connected to the upper end of the operating table 1. A movable frame 19 is movably connected inside the positioning block 18. A protrusion 21 is provided at one end of the movable frame 19. A movable rod 23 is connected to one side of the fixed plate 22. A fixed frame 24 is fixedly connected to one end of the operating table 1. A motor 25 is fixedly connected to the upper end of the fixed frame 24. A threaded rod 26 is rotatably connected to the output end of the motor 25. The outer side of the threaded rod 26 is threadedly connected to the welding machine 6. A pulley A27 is fixedly connected to the end of the threaded rod 26 away from the motor 25. A belt 28 is sleeved inside the pulley A27. A pulley B29 is sleeved at the end of the belt 28 away from the pulley A27. A bracket is movably connected to one end of the threaded rod 26. The other end of the bracket is movably connected to the pulley B29.

[0027] In an optional embodiment, two sets of sliding grooves 2 are provided on both sides of the operating table 1. The welding machine 6 is slidably connected inside the sliding grooves 2. Two sets of positioning grooves 3 are fixedly connected to the upper surface of the operating table 1. Each of the two sets of positioning grooves 3 is provided with a limit block 4 on one side of the motor 25. A spring rod A5 is fixedly connected to the lower end of the limit block 4. The spring rod A5 extends through the operating table 1 to the lower end. Before welding, the worker pushes the steel frame into the positioning groove 3. The end of the limit block 4 near the outside is inclined. When the limit block 4 contacts the steel frame, the limit block 4 will retract downward by the force of the spring rod A5. As the steel frame gradually and completely enters the positioning groove 3, the limit block 4 will move upward again by the force of the spring rod A5, thereby limiting the steel frame inside the positioning groove 3 and preventing the steel frame from deviating during welding. After the steel frame is fixed, the remaining steel frame is placed between the two sets of steel frames for welding.

[0028] In an optional embodiment, two sets of sliding grooves 2 are provided on both sides of the operating table 1. The welding machine 6 is slidably connected inside the sliding groove 2. The spring rod A5 extends through the operating table 1 to the lower end. As described above, when the steel frame gradually enters the positioning groove 3, the steel frame will contact the movable plate 7, and the movable plate 7 will gradually move backward as the steel frame moves. At the same time as the movable plate 7 moves, it will simultaneously drive the push rod 8 to move to the other end. After welding is completed, when the steel frame is removed from the positioning groove 3, the squeezing force of the steel frame on the movable plate 7 is canceled, and the movable plate 7 will automatically reset through the elastic force applied by the spring 9 to the push rod 8.

[0029] In an optional embodiment, a rack A10 is fixedly connected to the outside of the push rod 8, and a gear A11 is provided on the outside of the suction pipe 12. A rotating shaft A is fixedly connected to the side of the gear A11 near the suction pipe 12. One end of the rotating shaft A extends through the suction pipe 12 and connects to the valve. The gear A11 and the rack A10 are located on the same plane and mesh with each other. The suction groove 13 is embedded in the upper surface of the operating table 1. One end of the suction pipe 12 is connected to the suction groove 13, and the other end is connected to the exhaust fan. As described above, when the push rod 8 moves towards... When the device moves outward, it will synchronously drive the rack A10 to move. When the rack A10 moves, it will come into contact with the gear A11, thereby driving the gear A11 to rotate. After the gear A11 rotates, it will open the valve inside the exhaust pipe 12, so that the exhaust fan can draw air through the exhaust pipe 12. The exhaust pipe 12 will quickly collect the fumes generated during welding through the exhaust groove 13, thereby preventing the fumes from spreading in the workshop and preventing workers from inhaling the dust, thus protecting the health and safety of the workers and reducing environmental pollution.

[0030] In an optional embodiment, a rack B14 is fixedly connected to the outer side of another set of push rods 8, and a gear B15 is provided on the outer side of the air intake pipe 16. A rotating shaft B is provided at one end of the gear B15 near the air intake pipe 16. The rotating shaft B extends through the air intake pipe 16 and connects to the valve inside. The gear B15 rotates via the rack B14. One end of the air intake pipe 16 is connected to a hot air blower, and the other end is connected to an air duct 17. The air duct 17 is fixedly connected to the upper surface of the operating table 1. When the push rod 8 is pushed out, it simultaneously drives the rack B14 automatically. When the rack B14 is automatic, it will... The gear B15 is rotated, thereby opening the valve inside the air intake pipe 16. After the valve is opened, the air intake pipe 16 will transport the hot air generated by the hot air blower and then release it through the air duct 17. Because the air duct 17 is located at a low position, the hot air will preheat the steel frame before welding. This prevents some high-strength steels from developing hardened structures during the welding cooling process, which would reduce the toughness of the weldment, increase its brittleness, and make it prone to cracking. In addition, proper preheating can make the metal structure of the welded joint more uniform and reduce the generation of welding defects such as porosity and slag inclusions.

[0031] In an optional embodiment, the movable rod 23 is movably connected to the center of one side of the fixed plate 22. A snap-fit ​​groove is provided at the axis of the movable rod 23. When the push rod 8 is pushed out, it will push the fixed plate 22 to move synchronously. After the fixed plate 22 moves, it will drive the movable rod 23 to move synchronously. After the movable rod 23 moves, the movable rod 23 will be located on the same plane as the protrusion 21.

[0032] When the welding machine 6 needs to be moved, the threaded rod 26 is driven to rotate by the motor 25. When the threaded rod 26 rotates, it will drive the welding machine 6 to move. The inner diameter of its pulley B29 is smaller than the outer diameter of the pulley A27. When the threaded rod 26 rotates, it will synchronously drive the pulley A27 to rotate. When the pulley A27 rotates, it will drive the pulley B29 to rotate synchronously through the belt 28. The rotation speed of the pulley B29 is greater than that of the pulley A27.

[0033] In an optional embodiment, a connecting rod 30 is fixedly connected to the side of the pulley B29 near the fixed plate 22. The end of the connecting rod 30 near the movable rod 23 is a snap-fit ​​rod. The snap-fit ​​rod matches the snap-fit ​​groove at the axis of the movable rod 23, and the snap-fit ​​rod and the snap-fit ​​groove are located on the same plane. As described above, when the fixed plate 22 drives the movable rod 23 to move to one side, the axis of the movable rod 23 will snap into the connecting rod 30, so that when the pulley B29 rotates, it will synchronously drive the movable rod 23 to rotate.

[0034] In an optional embodiment, one end of the movable frame 19 is provided with two sets of support rods, which are located at the upper end of the positioning groove 3. The other end of the movable frame 19 is fixedly connected to two sets of connecting plates. The protrusion 21 is located at the center of the two sets of connecting plates. Two sets of spring rods B20 are fixedly connected to both sides of the protrusion 21. The other ends of the two sets of spring rods B20 are fixedly connected to their respective connecting plates. As described above, when the movable rod 23 rotates, it will contact the protrusion 21, thereby causing the protrusion 21 to drive the movable frame 19 to move downward a certain distance. After the movable frame 19 can no longer move, as the movable frame 19 continues to rotate, the protrusion 21 will flip due to the force of the two sets of spring rods B20, thereby causing the movable rod 23 to disengage from the protrusion 21. After the protrusion 21 flips, it will... The spring rod B20 resets the support rod. Since the support rod is located at the upper end of the two sets of steel frames and is fixedly connected to the movable frame 19, when the protrusion 21 is squeezed, the two sets of support rods will move upward synchronously through the movable frame 19. After the movable rod 23 is disengaged from the protrusion 21, the support rod will automatically descend under gravity, thereby striking the steel frame and causing it to vibrate. The striking vibration can cause the weldment to undergo slight plastic deformation through external force, which promotes the release and redistribution of stress in the stress concentration area, thereby reducing the residual stress of welding and reducing the risk of structural deformation and cracking caused by residual stress. At the same time, the striking vibration can refine the grains inside the weld metal, which helps to improve the mechanical properties of the weld, such as strength, toughness and ductility.

[0035] Working principle: Before welding, the worker pushes the steel frame into the positioning groove 3. The end of the limiting block 4 near the outside is inclined. When the limiting block 4 comes into contact with the steel frame, the limiting block 4 will retract downward by the force of the spring rod A5. As the steel frame gradually and completely enters the positioning groove 3, the limiting block 4 will move upward again by the force of the spring rod A5, thereby limiting the steel frame inside the positioning groove 3. After the steel frame is fixed, the remaining steel frame is placed between the two sets of steel frames for welding.

[0036] As the steel frame gradually enters the positioning groove 3, it will come into contact with the movable plate 7. As the steel frame moves, the movable plate 7 will gradually move backward. At the same time as the movable plate 7 moves, it will simultaneously drive the push rod 8 to move to the other end. When the push rod 8 moves outward, it will simultaneously drive the rack A10 to move. When the rack A10 moves, it will come into contact with the gear A11. As a result, the rack A10 will drive the gear A11 to rotate. After the gear A11 rotates, it will open the valve inside the exhaust pipe 12, so that the exhaust fan can draw air through the exhaust pipe 12.

[0037] As push rod 8 is pushed out, it will simultaneously drive rack B14 to rotate automatically. When rack B14 rotates automatically, it will drive gear B15 to rotate, thereby opening the valve inside air intake pipe 16. After the valve is opened, air intake pipe 16 will transport the hot air generated by hot air blower and release it through air duct 17. When the hot air is released, it will preheat the steel frame before welding. When push rod 8 is pushed out, it will simultaneously push fixed plate 22 to move.

[0038] After the fixed plate 22 moves, it will drive the movable rod 23 to move synchronously. After the movable rod 23 moves, the movable rod 23 will be on the same plane as the protrusion 21. When the fixed plate 22 drives the movable rod 23 to move to one side, the axis of the movable rod 23 will be engaged with the connecting rod 30.

[0039] When the welding machine 6 needs to be moved, the threaded rod 26 is driven to rotate by the motor 25. The rotation of the threaded rod 26 drives the welding machine 6 to move. Simultaneously, the rotation of the threaded rod 26 drives the pulley A27 to rotate. The rotation of pulley A27, in turn, drives the pulley B29 to rotate synchronously via the belt 28. When the movable rod 23 rotates, it contacts the protrusion 21, causing the protrusion 21 to move the movable frame 19 downwards a certain distance. After the movable frame 19 can no longer move, it continues to move downwards. As the frame 19 continues to rotate, the protrusion 21 will flip under the force of the two sets of spring rods B20, thereby causing the movable rod 23 to disengage from the protrusion 21. After the protrusion 21 flips, it will reset again through the spring rods B20. Since the support rod is located at the upper end of the two sets of steel frames and is fixedly connected to the movable frame 19, when the protrusion 21 is squeezed, it will drive the two sets of support rods to move upward synchronously through the movable frame 19. After the movable rod 23 disengages from the protrusion 21, the support rod will automatically descend under gravity, thereby striking the steel frame.

[0040] 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 kind of operating platform for welding steel structure net rack, including operating table (1), it is characterized in that, Two groups of positioning grooves (3) are fixedly connected to the upper surface of the operating table (1), and a limiting block (4) is arranged on one side of each of the two groups of positioning grooves (3). A spring rod A (5) is fixedly connected to the lower end of the limiting block (4). A welding machine (6) is arranged at the upper end of the operating table (1). A movable plate (7) is arranged in the positioning groove (3). The two groups of movable plates (7) are arranged in the positioning groove (3). A push rod (8) is fixedly connected to one end of each of the two groups of movable plates (7). The push rod (8) extends to the outside through the operating table (1) away from the movable plate (7). A spring (9) is arranged on the outside of the push rod (8). One end of the spring (9) is fixedly connected to the push rod (8), and the other end is fixedly connected to the operating table (1). A fixed plate (22) is connected to one end of the push rod (8). An air extraction groove (13) is arranged in the operating table (1). An air extraction pipe (12) is connected to the lower end of the air extraction groove (13). An air inlet pipe (16) is arranged on one side of the fixed plate (22). One end of the air inlet pipe (16) is connected to a blowing groove (17). A positioning block (18) is fixedly connected to the upper end of the operating table (1). The positioning block (18) is movably connected to a movable frame (19). The movable frame (19) is provided with a protruding block (21) at one end. An operating rod (23) is connected to one side of the fixed plate (22). A fixed frame (24) is fixedly connected to one end of the operating table (1). A motor (25) is fixedly connected to the upper end of the fixed frame (24). A threaded rod (26) is rotatably connected to the output end of the motor (25). The threaded rod (26) is screw-connected with the welding machine (6) on the outside. A belt pulley A (27) is fixedly connected to the end of the threaded rod (26) away from the motor (25). A belt (28) is sleeved in the belt pulley A (27). A belt pulley B (29) is sleeved at the end of the belt (28) away from the belt pulley A (27). The threaded rod (26) is movably connected to a support. The other end of the support is movably connected to the belt pulley B (29).

2. The operating platform for welded steel structure space truss according to claim 1, characterized in that, Two groups of sliding grooves (2) are formed on the two sides of the operating table (1). The welding machine (6) is slidingly connected in the sliding groove (2). The spring rod A (5) extends to the lower end through the operating table (1).

3. The operating platform for welded steel structure space truss according to claim 1, characterized in that, One end of the threaded rod (26) is movably connected to a support. The other end of the support is movably connected to the belt pulley B (29).

4. The operating platform for welded steel structure space truss according to claim 1, characterized in that, Another group of said push rod (8) outside fixed connection has a rack B (14), the air inlet pipe (16) outside is provided with gear B (15), the gear B (15) is close to the one end of air inlet pipe (16) is provided with rotating shaft B, the rotating shaft B extends through air inlet pipe (16) to inside and is connected with valve, the gear B (15) is rotated through rack B (14), the air inlet pipe (16) one end is connected with hot air machine, the other end is connected with blowing groove (17), the blowing groove (17) is fixedly connected on the upper surface of operation table (1).

5. The operating platform for welded steel structure space truss according to claim 1, characterized in that, The movable rod (23) is movably connected at the center of one side of the fixed plate (22), and the movable rod (23) is provided with a clamping groove at the shaft center.

6. The operating platform for welded steel structure space truss according to claim 1, characterized in that, The pulley B (29) is fixedly connected with a connecting rod (30) on one side close to the fixed plate (22), one end of the connecting rod (30) close to the movable rod (23) is a clamping rod, the clamping rod is matched with the clamping groove at the shaft center of the movable rod (23), and the clamping rod and the clamping groove are located in the same plane.

7. The operating platform for welded steel structure space truss according to claim 1, characterized in that, The movable frame (19) is provided with two groups of supporting rods at one end, and the two groups of supporting rods are located at the upper end of the positioning groove (3). The movable frame (19) is fixedly connected with two groups of connecting plates at the other end. The protrusion (21) is located at the center of the two groups of connecting plates. The protrusion (21) is fixedly connected with two groups of spring rods B (20) on both sides. The other end of the two groups of spring rods B (20) is fixedly connected with the corresponding connecting plate.

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