A welding device for a crane accessory

Abstract

The utility model relates to welding equipment technical field discloses a kind of welding device of crane fittings, including workbench, the inside rotation connection of workbench has fixed mechanism, the top of workbench is fixedly connected with welding machine, the front side fixed connection of welding machine has fixed ring, the bottom of fixed ring is fixedly connected with dismounting mechanism, the fixed mechanism includes round table, the outside rotation connection of round table in the inside of workbench, the inside fixed connection of round table has electric push rod, the drive end fixed connection of electric push rod has moving rod, the inside of moving rod is rotatably connected with two connecting rods. In the utility model, electric push rod drive rack linkage mechanism, make clamp rod one clamps fittings, motor drives round table rotation angle adjustment, realize fixed and rotating fittings integration operation when welding, reduce labor intensity, improve welding quality and efficiency.

Description

Technical Field

[0001] This utility model relates to the field of welding equipment technology, and in particular to a welding device for crane accessories. Background Technology

[0002] Crane parts welding equipment is a type of welding equipment used for the manufacturing and repair of crane parts. It enables efficient and precise welding operations. The welding equipment is adaptable to various welding processes and is suitable for connecting parts of different materials and specifications. It is widely used in the crane machinery industry and can improve production efficiency and welding quality.

[0003] The crane parts welding device achieves connection by melting metal with electric arc. The device sets welding parameters through a CNC system, and the robotic arm moves the welding torch to the welding position. Current passes through the welding torch and forms an electric arc with the workpiece, generating high temperature to melt the welding wire and base material. At the same time, protective gas or flux isolates the air to prevent oxidation of the molten pool. The weld tracking sensor corrects deviations in real time to ensure uniform forming. After completion, the cooling system quickly cools down the joint to achieve the design strength and realize a stable connection of the parts.

[0004] In the existing technology, some crane component welding devices are prone to displacement during operation due to the impact of electric arc and thermal deformation, resulting in weld position deviation and dimensional deviation. This can easily lead to safety accidents during crane use. At the same time, components may be scrapped due to substandard precision or have their lifespan shortened due to uneven stress after assembly. Therefore, a crane component welding device is proposed to solve the above problems. Utility Model Content

[0005] To overcome the above deficiencies, this utility model provides a welding device for crane accessories, which aims to improve the existing crane accessory welding device. During welding, the accessories are easily affected by electric arc impact and thermal deformation, resulting in displacement, weld offset, dimensional deviation, and thus safety hazards. In addition, the device may cause the scrapping of accessories that do not meet the precision requirements and the shortening of equipment life due to uneven stress after assembly.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A welding device for crane accessories includes a workbench, a fixing mechanism installed inside the workbench, a welding machine fixedly connected to the top of the workbench, a fixing ring fixedly connected to the front side of the welding machine, and a disassembly mechanism installed at the bottom of the fixing ring. The fixing mechanism includes a frustum, the outer side of which is rotatably connected to the inside of the workbench. An electric push rod is fixedly connected inside the frustum, and a moving rod is fixedly connected to the drive end of the electric push rod. Two connecting rods are rotatably connected to the inner side of each moving rod, and two clamping assemblies are installed at the other ends of each of the two connecting rods. A motor is fixedly connected inside the workbench, and a drive wheel is fixedly connected to the drive end of the motor. A belt is sleeved on the outer side of the drive wheel, and a driven shaft is rotatably connected to the other end of the belt. As a further description of the above technical solution: The clamping assembly includes a linkage rod, the inner side of which is rotatably connected to the outer side of the connecting rod. A rotating shaft is fixedly connected inside the linkage rod, and a gear is fixedly connected to the outer side of the rotating shaft. Two sliding columns are slidably connected inside the frustum, and two racks are fixedly connected to the bottom ends of the two sliding columns. The outer side of the gear is meshed with the front side of the rack. A clamping rod is fixedly connected to the top of the two racks, and a placement platform is fixedly connected to the top of the frustum. As a further description of the above technical solution: The disassembly mechanism includes a protective shell, the top of which is fixedly connected to the bottom of the fixing ring. A lever is slidably connected inside the protective shell, and a connecting shaft is fixedly connected to the bottom of the lever. A spring is fixedly connected to the outside of the connecting shaft, and a transmission rod is fixedly connected to the front of the connecting shaft. A driven rod is fixedly connected to the other end of the transmission rod, and two linkage components are installed on the inner side of each driven rod. A limit rod is slidably connected inside the protective shell. As a further description of the above technical solution: The linkage assembly includes a rotating rod, the outer side of which is rotatably connected to the inner side of the driven rod. The other end of the rotating rod is fixedly connected to a central rotating shaft. The outer side of the central rotating shaft is rotatably connected to a C-shaped rod. The other end of the C-shaped rod is rotatably connected to a second fixed shaft. The outer side of the central rotating shaft is rotatably connected to a fixed rod. The other end of the fixed rod is rotatably connected to a second clamping rod. The inside of the second clamping rod is fixedly connected to a first fixed shaft. As a further description of the above technical solution: The outer side of the rotating shaft is rotatably connected to the inside of the frustum, and the inner side of the linkage rod is fixedly connected to the outer side of the gear. As a further description of the above technical solution: The frustum has two sliding grooves inside, and the outer side of the sliding column is slidably connected to the inside of the sliding grooves. The frustum also has two square grooves inside, and the outer side of the clamping rod is slidably connected to the inner side of the square grooves. As a further description of the above technical solution: The other end of the spring is fixedly connected to the bottom end of the lever, and the outer side of the transmission rod is slidably connected to the inside of the protective shell; As a further description of the above technical solution: The outer side of the first fixed shaft is rotatably connected to the inside of the protective shell, the outer side of the second fixed shaft is fixedly connected to the inside of the protective shell, the outer side of the fixed rod is rotatably connected to the inside of the C-shaped rod, and the bottom end of the limiting rod is in contact with the top end of the lever.

[0007] This utility model has the following beneficial effects: 1. In this utility model, an electric push rod drives a moving rod, which in turn drives a connecting rod and a linkage rod to rotate, causing the gears to mesh with the rack and pinion to move left and right. When the two racks move towards each other, a clamping rod fixes the accessory, and the motor drives the drive wheel and driven shaft to rotate, causing the frustum to rotate, thereby adjusting the angle of the accessory. This allows the fixed accessory to rotate simultaneously during welding, enabling welding to be performed in conjunction with the welding machine, reducing labor intensity, improving efficiency, avoiding welding dead angles, and ensuring weld quality.

[0008] 2. In this utility model, after removing the limiting rod, the lever is moved to drive the connecting shaft to compress the spring and drive the transmission rod, so that the driven rod drives the central rotating shaft to move through the rotating rod. The central rotating shaft drives the C-shaped rod to rotate around the second fixed shaft. At the same time, the fixed rod drives the second clamping rod to rotate around the first fixed shaft, so that the second clamping rod opens. After the air nozzle is inserted, the lever is released, the spring returns to its original position, and the second clamping rod clamps the air nozzle. Finally, the limiting rod is inserted back to fix it. This allows for quick disassembly of the air nozzle, shortens maintenance time, reduces operating difficulty, and improves production efficiency. Attached Figure Description

[0009] Figure 1 This is a three-dimensional schematic diagram of a welding device for a crane accessory proposed in this utility model; Figure 2 This is a schematic diagram of the structure of a frustum of a welding device for a crane accessory proposed in this utility model; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 for Figure 1 Enlarged view of point B in the middle; Figure 5 This is a schematic diagram of the protective shell of a welding device for a crane accessory proposed in this utility model.

[0010] Legend: 1. Worktable; 2. Fixing mechanism; 21. Frustum; 22. Electric push rod; 23. Moving rod; 24. Connecting rod; 25. Clamping assembly; 251. Linkage rod; 252. Rotating shaft; 253. Gear; 254. Sliding column; 255. Rack; 256. Slide groove; 257. Clamping rod one; 258. Square slot; 259. Placement platform; 26. Motor; 27. Drive wheel; 28. Belt; 29. 1. Driven shaft; 3. Welding machine; 4. Fixing ring; 5. Disassembly mechanism; 51. Protective shell; 52. Lever; 53. Connecting shaft; 54. Spring; 55. Transmission rod; 56. Driven rod; 57. Linkage assembly; 571. Rotating rod; 572. Central shaft; 573. C-shaped rod; 574. Fixing rod; 575. Fixing shaft one; 576. Fixing shaft two; 577. Clamping rod two; 58. Limiting rod. Detailed Implementation

[0011] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0012] Reference Figures 1 to 3 This utility model provides an embodiment of a welding device for crane accessories, including a workbench 1. The workbench 1 is the foundation of the entire device, providing a platform for the installation and support of all other components, ensuring the stability of the entire device during operation. A fixing mechanism 2 is installed inside the workbench 1. The core function of the fixing mechanism 2 is to firmly fix the crane accessories to be welded, preventing displacement of the accessories during welding and ensuring the accuracy of the welding position.

[0013] A welding machine 3 is fixedly connected to the top of the workbench 1. The welding machine 3 is the core equipment for welding operations, generating the energy required for welding and processing the fixed crane accessories. A fixing ring 4 is fixedly connected to the front of the welding machine 3. The fixing ring 4 is used to connect subsequent components to the welding machine 3, providing a stable installation position for the subsequent components. A disassembly mechanism 5 is installed at the bottom of the fixing ring 4. The disassembly mechanism 5 facilitates the disassembly and replacement of the air nozzle, making the maintenance and repair of the device easier.

[0014] The fixing mechanism 2 includes a frustum 21, the outer side of which is rotatably connected to the inside of the worktable 1. The frustum 21 forms the main frame of the fixing mechanism 2, providing a mounting base for other components. An electric push rod 22 is fixedly connected inside the frustum 21. The electric push rod 22 acts as a power source, driving the moving rod 23 through its extension and retraction, which in turn drives the subsequent connecting rod 24 and clamping assembly 25 to clamp or release the parts. The driving end of the electric push rod 22 is fixedly connected to the moving rod 23, which transmits power, transferring the driving force of the electric push rod 22 to the connecting rod 24, enabling the connecting rod 24 to move along a specific trajectory.

[0015] Two connecting rods 24 are rotatably connected to the inner side of the moving rod 23. The connecting rods 24 connect the moving rod 23 and the clamping assembly 25, converting the linear motion of the moving rod 23 into the motion form required by the clamping assembly 25, realizing the transmission of force and the change of motion direction. Two clamping assemblies 25 are installed at the other end of each connecting rod 24. The clamping assemblies 25 are in direct contact with the crane accessories and clamp and fix the accessories through their own action.

[0016] A motor 26 is fixedly connected inside the worktable 1. The motor 26 provides power for the rotation of the frustum 21 and is the driving source for the rotation of the frustum 21. A drive wheel 27 is fixedly connected to the drive end of the motor 26. The drive wheel 27 rotates under the drive of the motor 26 and transmits power to the driven shaft 29 through a belt 28. A belt 28 is fitted on the outer side of the drive wheel 27, connecting the drive wheel 27 and the driven shaft 29, and playing the role of transmitting power so that the power of the motor 26 can be transmitted to the driven shaft 29, thereby driving the frustum 21 to rotate. The other end of the belt 28 is rotatably connected to the driven shaft 29, which rotates under the drive of the belt 28, thereby driving the frustum 21 to rotate.

[0017] The clamping assembly 25 includes a linkage rod 251, the inner side of which is rotatably connected to the outer side of the connecting rod 24, connecting the connecting rod 24 and the gear 253, transmitting the motion of the connecting rod 24 to the gear 253, causing the gear 253 to rotate. A rotating shaft 252 is fixedly connected inside the linkage rod 251, providing rotational support for the gear 253 and ensuring stable rotation of the gear 253. The gear 253 is fixedly connected to the outer side of the rotating shaft 252, and the gear 253 drives the rack 255 to perform linear motion through its own rotation, realizing power transmission and motion mode conversion.

[0018] The frustum 21 has two sliding pins 254 slidably connected inside, which are fixedly connected to the rack 255. Their sliding within the groove 256 guides and restricts the movement of the rack 255, ensuring that the rack 255 can only move linearly in a specific direction, thus improving the stability of the movement. The bottom ends of the two sliding pins 254 are fixedly connected to two racks 255. Driven by the gear 253, the racks 255 move linearly, thereby driving the clamping rod 257 to move.

[0019] The outer side of gear 253 is meshing with the front side of rack 255. Clamping rods 257 are fixedly connected to the top of both racks 255. Clamping rods 257 directly contact the crane parts and move closer to or further away from the parts under the action of the racks 255, completing the clamping or releasing action. A placement platform 259 is fixedly connected to the top of the frustum 21. The placement platform 259 is used to place the crane parts to be welded, providing a stable base for the parts and working with the clamping rods 257 to fix the parts in place.

[0020] Reference Figure 1 , Figure 4 , Figure 5 The disassembly mechanism 5 includes a protective shell 51, the top of which is fixedly connected to the bottom of the fixing ring 4. The protective shell 51 serves as the external protection and support structure for the disassembly mechanism 5, providing installation space and protection for the internal components. A lever 52 is slidably connected inside the protective shell 51. The lever 52 is the operating component of the disassembly mechanism 5; it drives the subsequent components, such as the connecting shaft 53, to move through external force, and is the starting component for transmitting external operating force.

[0021] A connecting shaft 53 is fixedly connected to the bottom end of the lever 52, connecting the lever 52 and the transmission rod 55, transmitting the movement of the lever 52 to the transmission rod 55. It also serves as the mounting carrier for the spring 54, providing a support point for the spring 54. A spring 54 is fixedly connected to the outer side of the connecting shaft 53. The spring 54 has an elastic return function; when the lever 52 moves under external force, the spring 54 generates elastic force, causing the lever 52 and related components to return to their initial position when the external force is removed, ensuring the disassembly mechanism 5 can be reused. A transmission rod 55 is fixedly connected to the front side of the connecting shaft 53, connecting the connecting shaft 53 and the driven rod 56, transmitting the movement of the connecting shaft 53 to the driven rod 56, thus serving as an intermediate transmission mechanism.

[0022] The other end of the transmission rod 55 is fixedly connected to a driven rod 56. The driven rod 56 receives the motion transmitted by the transmission rod 55 and transmits it to the linkage assembly 57, causing the linkage assembly 57 to move. Two linkage assemblies 57 are installed on the inner side of each driven rod 56. Through the cooperation of internal components, they clamp or release the target component, realizing the disassembly function. A limit rod 58 is slidably connected inside the protective shell 51. The surface of the limit rod 58 has a large friction force. When it is installed inside the protective shell 51, it prevents the lever 52 from moving, ensuring the stability of the device during operation.

[0023] The linkage assembly 57 includes a rotating rod 571, the outer side of which is rotatably connected to the inner side of the driven rod 56. The rotating rod 571 connects the driven rod 56 and the central shaft 572, transmitting the movement of the driven rod 56 to the central shaft 572, causing the central shaft 572 to rotate or move accordingly. The other end of the rotating rod 571 is fixedly connected to the central shaft 572, which provides connection and rotational support for the rotating rod 571, the C-shaped rod 573, and the fixed rod 574. This allows the movement of the rotating rod 571 to drive the C-shaped rod 573 and the fixed rod 574, serving as the pivot for the linkage of all components within the linkage assembly 57.

[0024] A C-shaped rod 573 is rotatably connected to the outer side of the central shaft 572. Driven by the central shaft 572, the C-shaped rod 573 rotates around the second fixed shaft 576, simultaneously driving the fixed rod 574 to move. Through its shape and motion trajectory, it provides a reasonable space and transmission path for the movement of the fixed rod 574 and the second clamping rod 577. The other end of the C-shaped rod 573 is rotatably connected to the second fixed shaft 576. The second fixed shaft 576 provides a fulcrum for the rotation of the C-shaped rod 573, ensuring that the C-shaped rod 573 can rotate stably around it, and serves as the reference point for the movement of the C-shaped rod 573.

[0025] A fixed rod 574 is rotatably connected to the outer side of the central shaft 572. The fixed rod 574 connects the central shaft 572 and the second clamping rod 577, transmitting the movement of the central shaft 572 to the second clamping rod 577, causing the second clamping rod 577 to rotate around the first fixed shaft 575, thus achieving clamping or releasing actions. The other end of the fixed rod 574 is rotatably connected to the second clamping rod 577, which directly contacts the air nozzle. The second clamping rod 577 achieves clamping or releasing of the target component through rotation around the first fixed shaft 575, and is a key component in the linkage assembly 57 for performing disassembly actions. The first fixed shaft 575 is fixedly connected internally to the second clamping rod 577, providing a fulcrum for rotation and ensuring stable rotation of the second clamping rod 577.

[0026] Reference Figure 1 , Figure 3 , Figure 5The outer side of the rotating shaft 252 is rotatably connected to the inside of the frustum 21. The rotating shaft 252 provides stable support for the gear 253, ensuring its stability during movement. The inner side of the linkage rod 251 is fixedly connected to the outer side of the gear 253. Two sliding grooves 256 are formed inside the frustum 21. The outer side of the sliding column 254 is slidably connected to the inside of the sliding grooves 256, which provide guidance for the sliding column 254, allowing it to slide along a preset direction. Two square slots 258 are formed inside the frustum 21. The outer side of the clamping rod 257 is slidably connected to the inner side of the square slots 258, which restrict the movement direction of the clamping rod 257. Through the coordinated action of the sliding column 254 and the clamping rod 257, the rack 255 is prevented from shifting during movement.

[0027] The other end of spring 54 is fixedly connected to the bottom end of lever 52. Lever 52 and protective shell 51 work together to stretch and compress spring 54, allowing spring 54 to use its elastic potential energy to reset its connected components. The outer side of transmission rod 55 is slidably connected to the inside of protective shell 51. The outer side of fixed shaft 575 is rotatably connected to the inside of protective shell 51, providing stable rotational support for clamping rod 577. The outer side of fixed shaft 576 is fixedly connected to the inside of protective shell 51, allowing C-shaped rod 573 to rotate using it as a fulcrum. The outer side of fixed rod 574 is rotatably connected to the inside of C-shaped rod 573, and the bottom end of limiting rod 58 contacts the top end of lever 52.

[0028] Working principle: When the electric push rod 22 is activated, it begins to move, driving the movable rod 23 fixedly connected to its drive end. The movement of the movable rod 23 causes the two connecting rods 24 to rotate. The movement of the connecting rods 24 causes the linkage rod 251 to rotate around the rotating shaft 252 as a fulcrum, allowing the gear 253 to drive the meshing rack 255 to move left and right. When the two racks 255 move towards each other, the clamping rod 257 moves along with them, thus fixing the parts. The motor 26 is activated, driving the drive wheel 27 to rotate. The drive wheel 27 transmits its motion to the driven shaft 29 via the belt 28, causing the driven shaft 29 to drive the frustum 21 to rotate. This allows the device to fix the parts during welding and adjust their direction and angle easily without moving them, reducing labor intensity, improving welding efficiency, achieving all-around welding of parts, avoiding welding dead angles, and ensuring weld quality.

[0029] Remove the limiting rod 58 and move the lever 52. The lever 52 receives external force and begins to move, driving the connecting shaft 53 to move. The movement of the connecting shaft 53 causes the spring 54 to undergo elastic deformation and store elastic potential energy. At the same time, the movement of the connecting shaft 53 drives the transmission rod 55 to move, which in turn causes the driven rod 56 to move. The movement of the driven rod 56 is transmitted to the central shaft 572 through the rotating rod 571, causing the central shaft 572 to simultaneously drive the C-shaped rod 573 and the fixed rod 574 to move. During the movement, the C-shaped rod 573 rotates around the fixed shaft 576 as the fulcrum, while the fixed rod 574 drives the clamping rod. Rotating around the fixed shaft 575 as a fulcrum, clamping rod 577 opens, allowing the air nozzle to be inserted into the inner side of clamping rod 577. Releasing lever 52 releases the force on spring 54, releasing elastic potential energy and causing a series of components to return to their original positions, clamping the air nozzle clamping rod 577. Finally, limiting rod 58 is returned to fix the movement state of the components, enabling convenient disassembly of the air nozzle, shortening downtime for maintenance, reducing the impact on the overall welding progress, and improving production efficiency. Simultaneously, the convenient disassembly device simplifies the air nozzle replacement process, reducing the difficulty and labor intensity for workers.

[0030] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A welding device for crane accessories, comprising a workbench (1), characterized in that: The workbench (1) is equipped with a fixing mechanism (2), a welding machine (3) is fixedly connected to the top of the workbench (1), a fixing ring (4) is fixedly connected to the front side of the welding machine (3), and a disassembly mechanism (5) is installed at the bottom of the fixing ring (4). The fixing mechanism (2) includes a frustum (21), the outer side of which is rotatably connected to the inside of the workbench (1). An electric push rod (22) is fixedly connected inside the frustum (21). A moving rod (23) is fixedly connected to the driving end of the electric push rod (22). Two connecting rods (24) are rotatably connected to the inner side of the moving rod (23). Two clamping assemblies (25) are installed at the other end of the two connecting rods (24). A motor (26) is fixedly connected inside the workbench (1). A drive wheel (27) is fixedly connected to the driving end of the motor (26). A belt (28) is sleeved on the outer side of the drive wheel (27). A driven shaft (29) is rotatably connected to the other end of the belt (28).

2. The welding device for crane accessories according to claim 1, characterized in that: The clamping assembly (25) includes a linkage rod (251), the inner side of which is rotatably connected to the outer side of the connecting rod (24). A rotating shaft (252) is fixedly connected inside the linkage rod (251), and a gear (253) is fixedly connected to the outer side of the rotating shaft (252). Two sliding columns (254) are slidably connected inside the frustum (21). Two racks (255) are fixedly connected to the bottom ends of the two sliding columns (254). The outer side of the gear (253) is meshed with the front side of the rack (255). A clamping rod (257) is fixedly connected to the top of the two racks (255). A placement platform (259) is fixedly connected to the top of the frustum (21).

3. The welding device for crane accessories according to claim 1, characterized in that: The disassembly mechanism (5) includes a protective shell (51), the top of which is fixedly connected to the bottom of the fixed ring (4). A lever (52) is slidably connected inside the protective shell (51). A connecting shaft (53) is fixedly connected to the bottom of the lever (52). A spring (54) is fixedly connected to the outside of the connecting shaft (53). A transmission rod (55) is fixedly connected to the front of the connecting shaft (53). A driven rod (56) is fixedly connected to the other end of the transmission rod (55). Two linkage components (57) are installed on the inner side of the driven rod (56). A limit rod (58) is slidably connected inside the protective shell (51).

4. The welding device for crane accessories according to claim 3, characterized in that: The linkage assembly (57) includes a rotating rod (571), the outer side of which is rotatably connected to the inner side of the driven rod (56). The other end of the rotating rod (571) is fixedly connected to a central shaft (572). The outer side of the central shaft (572) is rotatably connected to a C-shaped rod (573). The other end of the C-shaped rod (573) is rotatably connected to a fixed shaft two (576). The outer side of the central shaft (572) is rotatably connected to a fixed rod (574). The other end of the fixed rod (574) is rotatably connected to a clamping rod two (577). The inside of the clamping rod two (577) is fixedly connected to a fixed shaft one (575).

5. The welding device for crane accessories according to claim 2, characterized in that: The outer side of the rotating shaft (252) is rotatably connected to the inside of the frustum (21), and the inner side of the linkage rod (251) is fixedly connected to the outer side of the gear (253).

6. The welding device for crane accessories according to claim 2, characterized in that: The inner side of the truncated cone (21) has two sliding grooves (256), and the outer side of the sliding column (254) is slidably connected to the inner side of the sliding groove (256). The inner side of the truncated cone (21) has two square grooves (258), and the outer side of the clamping rod (257) is slidably connected to the inner side of the square groove (258).

7. The welding device for crane accessories according to claim 3, characterized in that: The other end of the spring (54) is fixedly connected to the bottom end of the lever (52), and the outer side of the transmission rod (55) is slidably connected to the inside of the protective shell (51).

8. The welding device for crane accessories according to claim 4, characterized in that: The outer side of the first fixed shaft (575) is rotatably connected to the inside of the protective shell (51), the outer side of the second fixed shaft (576) is fixedly connected to the inside of the protective shell (51), the outer side of the fixed rod (574) is rotatably connected to the inside of the C-shaped rod (573), and the bottom end of the limiting rod (58) is in contact with the top end of the lever (52).

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