Tensioning device for power cable installation

Abstract

This invention relates to the field of cable installation equipment technology, and discloses a tensioning device for power cable installation, including a bracket. A hook is rotatably connected to the top of the bracket, and a sheave is rotatably connected to the inner wall of the bracket. When the sheave rotates, it drives a toothed ring to rotate in the same direction. The toothed ring drives a double-acting screw to rotate through a gear. The double-acting screw drives a sliding frame to slide back and forth along the outer wall of a slide rail through a crescent-shaped guide block. At the same time, the slide rail drives a hollow frame to move back and forth through a tensioning component. The steel cable passing through the inner wall of the hollow frame will also slide back and forth left and right under the action of the hollow frame. The reciprocating movement of the steel cable will provide a lateral force to the side wall, so that when adjacent steel cables are stacked, the lateral force will force the steel cables to align in a single direction, preventing large-angle bending deformation of local steel cables due to mutual compression.

Description

Technical Field

[0001] This invention relates to the field of cable installation equipment technology, specifically a tensioning device for power cable installation. Background Technology

[0002] Power cables are cables made of one or more mutually insulated conductors and an outer insulating protective layer, used to transmit electricity or information from one place to another. During the installation process, cables usually need to be tensioned using a tensioning device to prevent them from failing to straighten during installation. The metal rope inside the tensioning device is mostly made of steel cable. Steel cable has extremely strong tensile strength, but it is not suitable for short-distance, large-angle changes. When the device is winding the rope, a pre-tightening process is required through the twisting lug. At this time, the steel cable will be in a slack state against the outer wall of the reel. When the subsequent tensioning process is carried out by the rocker arm, the steel cable will be in a taut state against the outer wall of the reel. At this time, the longer slack steel cable will be wrapped by the shorter outer steel cable. Some steel cables will bend at a short distance and large angle due to stacking. To address the above problems, the following solutions are proposed. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention provides a tensioning device for power cable installation, including a bracket, a hook rotatably connected to the top of the bracket, a sheave rotatably connected to the inner wall of the bracket, a steel cable fixedly connected to the outer wall of the sheave, a hook 2 placed at the end of the bracket away from the hook 1, and a roller rotatably connected to the inner wall of the hook 2, and further comprising: The collection mechanism is fixedly installed on the side wall of the reel; The pressure applying mechanism is fixedly installed on the inner wall of the support. The limiting mechanism is fixedly installed on the side wall of the pressure applying mechanism; The end of the steel cable away from the reel is fixedly connected to the side wall of the support, and the steel cable will pass through the first roller. When the reel rotates, the steel cable will drive the first roller to move up and down.

[0004] Preferably, the collection institutions include: A limiting component is fixedly installed on the side wall of the reel; A rocking component is fixedly mounted on the side wall of the limiting component; When the rocking component drives the limiting component to rotate, the limiting component will drive the sheave to rotate in one direction and wind up or release the steel cable.

[0005] Preferably, the pressure-applying mechanism includes: The movable component is fixedly installed on the inner wall of the bracket; The transmission assembly is rotatably mounted on the inside of the bracket; When the roller rotates, the transmission component will rotate and drive the moving component to slide back and forth.

[0006] Preferably, the limiting mechanism includes: A tensioning component is fixedly installed on the side wall of the movable component; A clamping component is fixedly disposed at the end of the pulling component away from the moving component; The steel cable will pass through the center of the clamping assembly. Under normal conditions, the pulling assembly will pull the steel cable toward the moving assembly through the clamping assembly.

[0007] Preferably, the limiting component includes a ratchet 1 fixedly connected to the side wall of the spool, a pawl 2 rotatably connected to the outer surface of the bracket, and a spring plate 1 fixedly connected to the side wall of the bracket; The other end of the spring plate is fixedly connected to the side wall of the pawl. Under normal conditions, the spring plate will push the pawl to rotate clockwise and force the end of the pawl to be locked in the tooth groove of the ratchet.

[0008] Preferably, the rocking assembly includes a fixed post fixedly connected to the side of the ratchet wheel away from the spool, a second ratchet wheel fixedly connected to the outer wall of the fixed post, a rocker arm rotatably connected to the outer wall of the fixed post, and a pawl rotatably connected to the inner wall of the rocker arm. When it is necessary to rotate ratchet one, the worker moves the right-side pawl upwards to ensure that the tip of the pawl is inserted into the groove of ratchet two teeth, and then rotates the rocker arm to rotate ratchet one.

[0009] Preferably, the movable component includes a slide rail fixedly connected to the inner wall of the bracket, and a sliding frame slidably connected to the outer wall of the slide rail. The inner wall of the sliding frame is rotatably connected to a crescent-shaped guide block. When the transmission assembly rotates, the transmission assembly drives the sliding frame to slide along the outer wall of the slide rail through the crescent-shaped guide block.

[0010] Preferably, the transmission assembly includes a gear rotatably connected to the inner wall of the bracket, a gear ring fixedly connected to the outer wall of the reel, and a bidirectional lead screw fixedly connected to the inner wall of the gear rotatably connected. The outer wall of gear one is meshed with the outer side of the gear ring. When the gear ring rotates, it will drive gear one and the double-acting lead screw to rotate in the opposite direction.

[0011] Preferably, the pulling assembly includes a telescopic rod fixedly connected to the side wall of the sliding frame, and a spring is fixedly connected to the inner wall of the telescopic rod; In normal conditions, spring one is in a contracted state.

[0012] Preferably, the clamping assembly includes a hollow frame fixedly connected to the end of the telescopic rod away from the sliding frame, a second roller is rotatably connected to the inner wall of the hollow frame, and an arc-shaped plate is fixedly connected to the top of the second roller. The steel cable will pass through the holes in the hollow frame and contact the outer wall of the second roller. The contact end between the second roller and the hollow frame is in a tight fit, which makes the second roller rotate with a certain resistance.

[0013] The present invention has the following beneficial effects: (1) The present invention utilizes the characteristics of the above-mentioned reel for collecting steel cables. A pressure-applying mechanism and a limiting mechanism are provided inside the equipment. When the reel rotates, it will drive the toothed ring to rotate in the same direction. The toothed ring drives the bidirectional screw to rotate through the gear one. The bidirectional screw drives the sliding frame to slide back and forth along the outer wall of the slide rail one through the crescent-shaped guide block. At the same time, the slide rail one drives the hollow frame to move back and forth through the pulling component. The steel cable passing through the inner wall of the hollow frame will also slide back and forth left and right under the drive of the hollow frame. The reciprocating steel cable will provide the steel cable with a force to move laterally to the side wall. When adjacent steel cables are stacked together, the lateral force will force the steel cables to align in a single direction, preventing the local steel cables from being subjected to large-angle bending deformation over a short distance due to mutual compression.

[0014] (2) The present invention utilizes the feature of the above-mentioned limiting mechanism to neatly arrange the steel cable on the outer wall of the reel. While effectively preventing the steel cable from bending over a short distance, it also avoids the steel cable from being bent for a long time in some areas, which would cause long-term deformation and accumulation of potential energy. When the cable extends outward at the bending position and is in the cable tensioning process, the potential energy accumulated at the bending position is large, which makes it impossible for the bending position to turn straight immediately. Under the tension of the cable's own weight, the bending position slowly turns straight, resulting in a secondary relaxation phenomenon.

[0015] (3) The present invention utilizes the characteristic of the steel cable passing through the inner wall of the hollow frame and sets up a tensioning component inside the equipment. When the equipment is pre-tightened, since the steel cable is in a relaxed state, the spring will drive the telescopic rod to contract. The contracted telescopic rod will drive the hollow frame to move in the direction of the slide rail. When the roller rotates, there is a certain rotational resistance. This allows the steel cable to adhere to the outer wall of the roller when the operator drives the pulley to pre-tighten it by twisting the lug. This prevents the steel cable from being suspended and coiled due to its own rigidity, which would affect the smooth arrangement of the steel cable during subsequent tightening. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a frontal schematic diagram of the overall structure of the present invention; Figure 2 This is a reverse schematic diagram of the overall structure of the present invention; Figure 3 This is a schematic diagram of the internal structure of the overall structure of the present invention; Figure 4 For the present invention Figure 3 Enlarged view of point A in the middle; Figure 5 This is a schematic diagram of the collection mechanism of the present invention; Figure 6 For the present invention Figure 5 Enlarged view of point C in the middle; Figure 7 For the present invention Figure 5 Enlarged view of point B in the middle; Figure 8 This is a cross-sectional schematic diagram of the transmission component of the present invention; Figure 9 For the present invention Figure 8 Enlarged view of point D in the middle; Figure 10 This is a schematic diagram of the overall operation of the device of the present invention.

[0018] The attached diagram lists the components represented by each number as follows: In the diagram: 1. Collection mechanism; 11. Limiting component; 12. Shaking component; 13. Bracket; 14. Hook 1; 15. Spool; 16. Steel cable; 17. Roller 1; 18. Hook 2; 111. Ratchet 1; 112. Pawl 2; 113. Spring plate 1; 121. Fixed column; 122. Ratchet 2; 123. Rocker arm; 124. Actuating pawl; 2. Pressure applying mechanism; 21. Moving component; 22. Transmission component; 211. Slide rail 1; 212. Sliding frame; 221. Gear 1; 222. Gear ring; 223. Bidirectional lead screw; 3. Limiting mechanism; 31. Pulling component; 32. Clamping component; 311. Telescopic rod; 312. Spring 1; 321. Hollow frame; 322. Roller 2; 323. Arc plate. Detailed Implementation

[0019] 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.

[0020] Example 1, please refer to Figures 1-7 This invention relates to a tensioning device for power cable installation, comprising a bracket 13, a hook 14 rotatably connected to the top of the bracket 13, a sheave 15 rotatably connected to the inner wall of the bracket 13, a steel cable 16 fixedly connected to the outer wall of the sheave 15, a hook 18 placed at the end of the bracket 13 away from the hook 14, and a roller 17 rotatably connected to the inner wall of the hook 18, and further comprising: Collection mechanism 1 is fixedly installed on the side wall of the reel 15; Pressure applying mechanism 2 is fixedly installed on the inner wall of bracket 13; Limiting mechanism 3 is fixedly installed on the side wall of pressure applying mechanism 2; The end of the steel cable 16 away from the spool 15 is fixedly connected to the side wall of the bracket 13, and the steel cable 16 will pass through the roller 17. When the spool 15 rotates, the steel cable 16 will drive the roller 17 to move up and down.

[0021] Collection agency 1 includes: Restriction component 11 is fixedly installed on the side wall of the reel 15; The rocking component 12 is fixedly installed on the side wall of the limiting component 11; When the rocking component 12 drives the limiting component 11 to rotate, the limiting component 11 will drive the spool 15 to rotate in one direction and wind up or release the steel cable 16.

[0022] Pressure mechanism 2 includes: Movable component 21 is fixedly installed on the inner wall of bracket 13; Transmission assembly 22 is rotatably mounted on the inner side of bracket 13; When the roller 15 rotates, the transmission component 22 will rotate and drive the moving component 21 to slide back and forth.

[0023] Limiting mechanism 3 includes: The tensioning component 31 is fixedly installed on the side wall of the movable component 21; Clamping component 32 is fixedly disposed at the end of pulling component 31 away from moving component 21; Among them, the steel cable 16 will pass through the center of the clamping assembly 32, and under normal conditions, the pulling assembly 31 will pull the steel cable 16 towards the moving assembly 21 through the clamping assembly 32.

[0024] Example 2, please refer to Figures 4-10 The present invention is a tensioning device for power cable installation. Based on the first embodiment, the limiting component 11 includes a ratchet 111 fixedly connected to the side wall of the pulley 15, a pawl 112 rotatably connected to the outer surface of the bracket 13, and a spring sheet 113 fixedly connected to the side wall of the bracket 13. By utilizing the aforementioned limiting mechanism 3 to neatly arrange the steel cable 16 on the outer wall of the reel 15, it effectively prevents the steel cable 16 from bending over a short distance. This also avoids the steel cable 16 from being bent in certain areas for extended periods, causing long-term deformation and accumulating potential energy. During the cable tensioning process, the large amount of potential energy accumulated at the bending point prevents the bending point from immediately straightening. Instead, under the subsequent tension of the cable's own weight, the bending point slowly straightens, leading to secondary slack.

[0025] The rocking assembly 12 includes a fixed post 121 fixedly connected to the side of the ratchet 111 away from the spool 15, a ratchet 122 fixedly connected to the outer wall of the fixed post 121, a rocker arm 123 rotatably connected to the outer wall of the fixed post 121, and a pawl 124 rotatably connected to the inner wall of the rocker arm 123. Before use, first connect hook 14 and hook 2 18 to the external wire clamp. Then, the worker pre-tightens the wire by twisting the lug on the side wall of the fixing post 121. After pre-tightening, when the worker needs to rotate ratchet 111, the worker moves the right-side pawl 124 upward to ensure that the tip of the pawl 124 is inserted into the tooth groove of ratchet 2 122. Then, the worker rotates the rocker arm 123 to drive ratchet 111 to rotate. Ratchet 111 will drive the wire wheel 15 to perform the wire winding process on the steel cable 16. During this process, the end of pawl 2 112 is locked in the tooth groove of ratchet 111 and restricts the reverse rotation of ratchet 111.

[0026] The movable component 21 includes a slide rail 211 fixedly connected to the inner wall of the bracket 13, and a sliding frame 212 slidably connected to the outer wall of the slide rail 211. The inner wall of the sliding frame 212 is rotatably connected to a crescent-shaped guide block. When the transmission assembly 22 rotates, the transmission assembly 22 drives the sliding frame 212 to slide along the outer wall of the slide rail 211 through the crescent-shaped guide block.

[0027] The transmission assembly 22 includes a gear 221 rotatably connected to the inner wall of the bracket 13, a gear ring 222 fixedly connected to the outer wall of the reel 15, and a bidirectional lead screw 223 fixedly connected to the inner wall of the gear 221. The outer wall of gear 221 meshes with the outer side of gear ring 222. When gear ring 222 rotates, it will drive gear 221 and bidirectional lead screw 223 to rotate in the opposite direction.

[0028] The tensioning assembly 31 includes a telescopic rod 311 fixedly connected to the side wall of the sliding frame 212, and a spring 312 fixedly connected to the inner wall of the telescopic rod 311. Taking advantage of the fact that the steel cable 16 passes through the inner wall of the hollow frame 321, a tensioning assembly 31 is installed inside the equipment. When the equipment is pre-tensioned, since the steel cable 16 is in a slack state, the spring 312 will cause the telescopic rod 311 to contract. The contracted telescopic rod 311 will then move the hollow frame 321 towards the slide rail 211, causing the equipment to... Figure 10 The state of the roller 322 and the rotational resistance of the roller 322 make the steel cable 16 adhere to the outer wall of the roller 15 when the operator uses the twisting lug to pre-tighten the wire wheel 15. This prevents the steel cable 16 from being suspended and coiled due to its own rigidity, which would affect the smooth arrangement of the steel cable 16 during subsequent tightening.

[0029] The clamping assembly 32 includes a hollow frame 321 fixedly connected to the end of the telescopic rod 311 away from the sliding frame 212. A second roller 322 is rotatably connected to the inner wall of the hollow frame 321, and an arc plate 323 is fixedly connected to the top of the second roller 322. Utilizing the characteristics of the reel 15 in collecting steel cable 16, a pressure applying mechanism 2 and a limiting mechanism 3 are provided inside the equipment. When the reel 15 rotates, it drives the toothed ring 222 to rotate in the same direction. The toothed ring 222 drives the bidirectional lead screw 223 to rotate through the gear 221. The bidirectional lead screw 223 drives the sliding frame 212 to slide back and forth along the outer wall of the slide rail 211 through the crescent-shaped guide block. At the same time, the slide rail 211 drives the hollow frame 321 to move back and forth simultaneously through the pulling component 31. The steel cable 16 passing through the inner wall of the hollow frame 321 will also slide back and forth left and right under the drive of the hollow frame 321. The reciprocating movement of the steel cable 16 will provide a force for lateral movement towards the side wall. When adjacent steel cables 16 are stacked together, the lateral force will force the steel cables 16 to align in a single direction, preventing large-angle bending deformation of the local steel cables 16 due to mutual compression.

[0030] A specific application of this embodiment is as follows: Before use, hook 14 and hook 2 18 are connected to the external wire clamp. Then, the worker pre-tightens the wire by twisting the lug on the side wall of the fixing post 121. After pre-tightening, when the worker needs to rotate ratchet 111, the worker moves the right-side pawl 124 upward to ensure that the tip of the pawl 124 is inserted into the tooth groove of ratchet 2 122. Then, the worker rotates the rocker arm 123 to drive ratchet 111 to rotate. Ratchet 111 will drive the wire wheel 15 to perform the wire winding process on the steel cable 16. During this process, the end of pawl 2 112 is locked in the tooth groove of ratchet 111 and restricts the reverse rotation of ratchet 111. Utilizing the characteristics of the reel 15 in collecting steel cable 16, a pressure applying mechanism 2 and a limiting mechanism 3 are provided inside the equipment. When the reel 15 rotates, it drives the toothed ring 222 to rotate in the same direction. The toothed ring 222 drives the bidirectional lead screw 223 to rotate through the gear 221. The bidirectional lead screw 223 drives the sliding frame 212 to slide back and forth along the outer wall of the slide rail 211 through the crescent-shaped guide block. At the same time, the slide rail 211 drives the hollow frame 321 to move back and forth simultaneously through the pulling component 31. The steel cable 16 passing through the inner wall of the hollow frame 321 will also slide back and forth left and right under the drive of the hollow frame 321. The reciprocating movement of the steel cable 16 will provide a force for lateral movement towards the side wall. When adjacent steel cables 16 are stacked together, the lateral force will force the steel cables 16 to align in a single direction, preventing large-angle bending deformation of the local steel cables 16 due to mutual compression.

[0031] By utilizing the aforementioned limiting mechanism 3 to neatly arrange the steel cable 16 on the outer wall of the reel 15, it effectively prevents the steel cable 16 from bending over a short distance. This also avoids the steel cable 16 from being bent in certain areas for extended periods, causing long-term deformation and accumulating potential energy. During the cable tensioning process, the large amount of potential energy accumulated at the bending point prevents the bending point from immediately straightening. Instead, under the subsequent tension of the cable's own weight, the bending point slowly straightens, leading to secondary slack.

[0032] Taking advantage of the fact that the steel cable 16 passes through the inner wall of the hollow frame 321, a tensioning assembly 31 is installed inside the equipment. When the equipment is pre-tensioned, since the steel cable 16 is in a slack state, the spring 312 will cause the telescopic rod 311 to contract. The contracted telescopic rod 311 will then move the hollow frame 321 towards the slide rail 211, causing the equipment to... Figure 10The state of the roller 322 and the rotational resistance of the roller 322 make the steel cable 16 adhere to the outer wall of the roller 15 when the operator uses the twisting lug to pre-tighten the wire wheel 15. This prevents the steel cable 16 from being suspended and coiled due to its own rigidity, which would affect the smooth arrangement of the steel cable 16 during subsequent tightening.

[0033] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A tensioning device for power cable installation, comprising a bracket (13), a hook I (14) is rotatably connected to the top of the bracket (13), a wire wheel (15) is rotatably connected to the inner wall of the bracket (13), a steel cable (16) is fixedly connected to the outer wall of the wire wheel (15), a hook II (18) is placed at the end of the bracket (13) away from the hook I (14), a roller I (17) is rotatably connected to the inner wall of the hook II (18), characterized in that, Also includes: A collection mechanism (1) is fixedly installed on the side wall of the reel (15); A pressure applying mechanism (2) is fixedly installed on the inner wall of the bracket (13); A limiting mechanism (3) is fixedly installed on the side wall of the pressure applying mechanism (2); The end of the steel cable (16) away from the spool (15) is fixedly connected to the side wall of the bracket (13), and the steel cable (16) will pass through the roller (17). When the spool (15) rotates, the steel cable (16) will drive the roller (17) to move up and down.

2. The tensioning device for power cable installation according to claim 1, characterized in that: The collection mechanism (1) includes: A limiting component (11) is fixedly disposed on the side wall of the reel (15); A rocking assembly (12) is fixedly disposed on the side wall of the limiting assembly (11); When the rocking component (12) drives the limiting component (11) to rotate, the limiting component (11) will drive the spool (15) to rotate in one direction and wind up or release the steel cable (16).

3. A tensioning device for power cable installation according to claim 2, characterized in that: The pressure application mechanism (2) includes: A movable component (21) is fixedly disposed on the inner wall of the bracket (13); A transmission assembly (22) is rotatably disposed on the inner side of the bracket (13); When the roller (15) rotates, the transmission component (22) will rotate and drive the moving component (21) to slide back and forth.

4. A tensioning device for power cable installation according to claim 3, characterized in that: The limiting mechanism (3) includes: A tensioning component (31) is fixedly disposed on the side wall of the movable component (21); A clamping assembly (32) is fixedly disposed at the end of the pulling assembly (31) away from the moving assembly (21); Among them, the steel cable (16) will pass through the center of the clamping assembly (32), and under normal conditions, the pulling assembly (31) will pull the steel cable (16) towards the moving assembly (21) through the clamping assembly (32).

5. A tensioning device for power cable installation according to claim 4, characterized in that: The limiting component (11) includes a ratchet (111) fixedly connected to the side wall of the reel (15), a pawl (112) rotatably connected to the outer surface of the bracket (13), and a spring plate (113) fixedly connected to the side wall of the bracket (13). The other end of the spring plate 1 (113) is fixedly connected to the side wall of the pawl 2 (112). Under normal conditions, the spring plate 1 (113) will push the pawl 2 (112) to rotate clockwise and force the end of the pawl 2 (112) to be locked in the tooth groove of the ratchet 1 (111).

6. A tensioning device for power cable installation according to claim 5, characterized in that: The rocking assembly (12) includes a fixed post (121) fixedly connected to the side of ratchet one (111) away from the spool (15), a ratchet two (122) fixedly connected to the outer wall of the fixed post (121), a rocker arm (123) rotatably connected to the outer wall of the fixed post (121), and a pawl (124) rotatably connected to the inner wall of the rocker arm (123). When it is necessary to rotate ratchet one (111), the worker moves the right-side pawl (124) upward to ensure that the tip of the pawl (124) is inserted into the tooth groove of ratchet two (122), and then rotates the rocker arm (123) to drive ratchet one (111) to rotate.

7. A tensioning device for power cable installation according to claim 4, characterized in that: The movable component (21) includes a slide rail (211) fixedly connected to the inner wall of the bracket (13), and a sliding frame (212) slidably connected to the outer wall of the slide rail (211). Among them, a crescent-shaped guide block is rotatably connected to the inner wall of the sliding frame (212). When the transmission component (22) rotates, the transmission component (22) drives the sliding frame (212) to slide along the outer wall of the slide rail (211) through the crescent-shaped guide block.

8. A tensioning device for power cable installation according to claim 4, characterized in that: The transmission assembly (22) includes a gear (221) rotatably connected to the inner wall of the bracket (13), a gear ring (222) fixedly connected to the outer wall of the spool (15), and a bidirectional lead screw (223) fixedly connected to the inner wall of the gear (221). Among them, the outer wall of gear one (221) is meshed with the outer side of the gear ring (222). When the gear ring (222) rotates, it will drive gear one (221) and the double-acting screw (223) to rotate in the opposite direction.

9. A tensioning device for power cable installation according to claim 8, characterized in that: The pulling assembly (31) includes a telescopic rod (311) fixedly connected to the side wall of the sliding frame (212), and a spring (312) is fixedly connected to the inner wall of the telescopic rod (311). Under normal conditions, spring 1 (312) is in a contracted state.

10. A tensioning device for power cable installation according to claim 9, characterized in that: The clamping assembly (32) includes a hollow frame (321) fixedly connected to one end of the telescopic rod (311) away from the sliding frame (212), and a roller (322) is rotatably connected to the inner wall of the hollow frame (321), and an arc plate (323) is fixedly connected to the top of the roller (322). Among them, the steel cable (16) will pass through the hole of the hollow frame (321) and contact the outer wall of the roller (322). The contact end of the roller (322) and the hollow frame (321) is in a tight fit, so that there is a certain resistance when the roller (322) rotates.

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