A fall prevention and shock absorption device for high altitude lifeline system

Abstract

The invention discloses a fall prevention and shock absorption device for a high-altitude lifeline system, which relates to the technical field of lifeline systems and comprises a shock absorber body, wherein the shock absorber body comprises a support member, a connecting member, a traction member, an alarm mechanism, a trigger mechanism and a shock absorption unit, wherein the support member is provided with an active cavity, the connecting member is fixedly connected to the support member, the traction member is movably connected to the support member, comprises a pulling section, a sliding rod and a limiting member, one end of the sliding rod is slidably penetrated in the active cavity and is fixedly connected to the limiting member, the other end of the sliding rod is fixedly connected to the pulling section, the shock absorption unit is slidably penetrated on the sliding rod, the trigger mechanism comprises a first contact piece and a second contact piece, both the first contact piece and the second contact piece are electrically connected to the alarm mechanism, when the impact force is too large, the limiting member sinks into the shock absorption unit, the first contact piece contacts the second contact piece, the alarm mechanism is energized to send an alarm signal, which intuitively reflects the shock absorption failure state of the fall prevention system and reduces the risk of inspection personnel climbing and falling.

Description

Technical Field

[0001] The present invention relates to the technical field of lifeline systems, and more particularly to a fall prevention and shock absorbing device for a high altitude lifeline system. Background Art

[0002] The safety lifeline system is a facility that provides continuous and uninterrupted mobile anchoring support for high-altitude workers within the coverage of the system through steel wire ropes and accessories fixed above the existing building structure. It is used to prevent falls when a fall occurs and ensure the safety of personnel at high altitudes. The safety lifeline system is divided into two categories: the anti-fall horizontal lifeline system and the anti-fall vertical lifeline system. The anti-fall horizontal lifeline system is an anchoring device that ensures the safety of personnel's horizontal movement. It is often installed on roofs, driving tracks, under awnings and other environments. It is also called a horizontal lifeline or horizontal safety line. The anti-fall vertical lifeline system is an anchoring device that ensures the safety of personnel's vertical movement. It is often installed in ladders, towers, deep wells and other environments. It is also called a vertical lifeline, vertical safety line, and vertical ladder protection system.

[0003] The safety lifeline system consists of anchor brackets, horizontal cables, shock absorbers, tensioners and other components. This device is generally permanently fixed to the existing building structure. The system adopts the concept of deformable technology and uses the deformation of the shock absorber to achieve the purpose of shock absorption during the descent process. The force generated during the descent process can be absorbed by components such as cables and shock absorbers, ensuring that one or more people can work safely at high altitudes where falls may occur, providing them with a freer space for activities.

[0004] For example, a Chinese patent with the existing publication number CN103949023A discloses a horizontal lifeline system, which includes a fixed support, an adjusting tensioning device, a lifeline, an intermediate support, an outer corner support, an inner corner support, and a buffer. One end of the fixed support is fixed to the fixed part, and the other end is connected to the buffer. The other end of the buffer is connected to the lifeline. The buffer has pre-tightening, energy absorption, and buffering functions. The elastic element inside it pre-tightens the lifeline system against the reaction force of the lifeline, converts the impact kinetic energy into elastic potential energy, and absorbs and reduces the impact force.

[0005] The existing fall prevention and shock absorption devices, i.e., buffers, on the market do not have any automatic alarm device after a fall occurs or after the buffer shock absorption fails. When the operator continues to use the lifeline without noticing the shock absorption failure, if a fall occurs, it will cause great harm to the human body. Moreover, since most fall prevention devices are installed at high places, the existing lifeline systems or other fall prevention devices on the market require inspectors to reach high places through aerial platforms or other aerial equipment before they can conduct inspections to determine whether the lifeline system can be used normally, which brings safety risks to the inspectors and increases the inspection and maintenance costs. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention aims to propose a fall prevention and shock absorption device for a high altitude lifeline system. By setting an alarm mechanism and a trigger mechanism, when the shock absorption unit produces irreversible deformation, the alarm mechanism is powered on to send an alarm signal to warn the inspection personnel to stop using the fall prevention device, which directly reflects the failure state of the shock absorption of the fall prevention system, reduces the risk of inspection personnel climbing and falling, and reduces the inspection and maintenance cost of the fall prevention system. The specific scheme is as follows:

[0007] A fall prevention and shock absorption device for a high altitude lifeline system comprises a shock absorber body, wherein the shock absorber body comprises a support member, a connecting member, a traction member, an alarm mechanism, a trigger mechanism and a shock absorption unit.

[0008] The support member is provided with an active cavity, and the shock absorbing unit, the trigger mechanism and the alarm mechanism are all located in the active cavity;

[0009] The connecting component is used to install and fix the shock absorber body, is located on one side of the support member and is fixedly connected to the support member;

[0010] The traction component is used to drive the shock absorbing unit to reciprocate and extend in the movable cavity, is located on the other side of the support member and is movably connected to the support member, and includes a pulling section, a sliding rod and a limiting member, one end of the sliding rod is slidably arranged in the movable cavity and is fixedly connected to the limiting member, the other end of the sliding rod extends out of the support member and is fixedly connected to the pulling section, and the shock absorbing unit is slidably arranged on the sliding rod;

[0011] The trigger mechanism comprises a first contact piece connected to the limiter and a second contact piece fixedly connected to the shock absorbing unit, and the first contact piece and the second contact piece are both electrically connected to the alarm mechanism;

[0012] When the shock absorbing unit is compressed and the limiting member is located between the shock absorbing unit and the sliding rod, the first contact piece contacts the second contact piece, and the alarm mechanism is powered on to send out an alarm signal.

[0013] Through the above technical solution, during normal operation, when a person falls, a large impact force is generated, and the cable pulls the pulling section to move away from the support member, driving the sliding rod to slide away from the support member. At this time, the shock absorbing unit is compressed to generate elastic potential energy, and the elastic force generated by the shock absorbing unit absorbs part of the impact force, thereby achieving a buffering effect and reducing the damage caused by the impact force to the human body; when the weight of the human body is too large and the height of the human body falling is high, an instantaneous huge impact force will be generated, and the limiter will be sunk between the shock absorbing unit and the sliding rod under the action of the huge impact force, prompting the first contact piece to contact the second contact piece, the circuit is turned on, and the alarm mechanism is energized to send an alarm signal, warning the detection personnel to stop using the anti-fall device, intuitively reflecting the shock absorption failure state of the anti-fall system, and warning the operator that the anti-fall device has a safety risk, thereby increasing the risk warning function of the anti-fall equipment, because the shock absorbing unit is stretched open after the limiter is sunk into the shock absorbing unit, resulting in the failure of the shock absorbing unit, and it is directly replaced, reducing the number of times the inspectors climb up to check and the risk of falling, and reducing the inspection and maintenance costs of the anti-fall system.

[0014] Furthermore, the first contact piece is located on the side of the limiting member facing the shock absorbing unit, the shock absorbing unit is provided with a through hole adapted to the sliding rod, the second contact piece is located between the shock absorbing unit and the sliding rod, and the second contact piece is fixedly connected to the inner wall of the shock absorbing unit at the through hole.

[0015] With the above technical solution, when the limiter extends between the shock absorbing unit and the sliding rod, the first contact piece can directly contact the second contact piece in the through hole, thereby improving the accuracy of conduction between the first contact piece and the second contact piece, thereby improving the accuracy of the alarm.

[0016] Furthermore, the limiting member includes a limiting nut threadedly connected to the sliding rod, the first contact piece is in a circular ring shape, the first contact piece is coaxially arranged with the limiting nut, the first contact piece extends between the shock absorbing unit and the sliding rod, and the first contact piece is integrally connected with a first energized spring piece, and the first energized spring piece is outside the shock absorbing unit.

[0017] Through the above technical solution, the surface area of ​​the first contact piece is increased, thereby increasing the contact area between the first contact piece and the second contact piece, and improving the accuracy of conduction between the two. In addition, the setting of the first energized spring piece is convenient for winding the wire to achieve electrical connection with the alarm mechanism, and the first energized spring piece is located outside to ensure that the limit nut does not affect the compression of the shock absorbing unit when the shock absorbing device works normally.

[0018] Furthermore, the second contact piece is in a circular ring shape, and a second energized elastic piece is integrally connected to the second contact piece, and the second energized elastic piece is located outside the shock absorbing unit.

[0019] Through the above technical solution, the surface area of ​​the second contact piece is increased, thereby increasing the contact area between the first contact piece and the second contact piece, and improving the accuracy of conduction between the two. In addition, the setting of the second energized spring piece is convenient for winding the wire to achieve electrical connection with the alarm mechanism, and the second energized spring piece is located outside to ensure that the shock absorbing device does not affect the shock absorbing unit when it works normally.

[0020] Furthermore, the end of the first energized elastic piece away from the first contact piece and the end of the second energized elastic piece away from the second contact piece are both arranged close to the alarm mechanism.

[0021] Through the above technical solution, the first energized spring piece, the second energized spring piece and the alarm mechanism are conveniently electrically connected, and the use of conductive wires is reduced, thereby reducing the length of the conductive wires in the active cavity, providing deformation space for the shock absorbing unit, and facilitating normal deformation of the shock absorbing unit.

[0022] Furthermore, the connecting component includes a connecting rod and a first limiting ring, the connecting rod is passed through the supporting member and both ends of the connecting rod extend out of the supporting member, and two first limiting rings are provided and are fixedly connected to both ends of the connecting rod respectively.

[0023] Through the above technical solution, a closed shape is formed between the connecting rod and the support member, which facilitates connecting the support member as a whole with other components on the lifeline system through hooks or other connecting members.

[0024] Furthermore, the support member is provided with a through slot communicating with the movable cavity at the connection rod to form an opening, and the through slot extends to the support member to form two spaced connection gaps.

[0025] Through the above technical solution, it is convenient for a larger hook or cable to extend out from the connecting gap, thereby facilitating installation or disassembly.

[0026] Furthermore, the alarm mechanism includes an audible and visual alarm device, which includes a fixing seat fixedly installed in the movable cavity and a light-emitting member fixedly connected to the fixing seat, and the light-emitting member is arranged toward the opening.

[0027] Through the above technical solution, when an alarm signal is generated, the sound and light alarm device emits a high-decibel alarm sound and simultaneously emits a red light flashing alarm. The light-emitting component is arranged toward the opening, so that the brightness of the light-emitting component can be emitted from the opening at the connecting rod, thereby facilitating the detection personnel to observe the alarm signal.

[0028] Furthermore, the sound and light alarm device is arranged close to the connecting rod.

[0029] Through the above technical solution, the distance between the light-emitting element and the opening is reduced, so that the area where the red light diverges outwards is increased, which better enables the detection personnel to see the alarm signal in time.

[0030] Furthermore, the pulling section is in a "U" shape as a whole, and pins are passed through both ends of the pulling section. Both ends of the pin extend out of the pulling section, and both ends of the pin are fixedly connected to a second limiting ring.

[0031] Through the above technical solution, a closed shape is formed between the pulling section and the pin, which facilitates the connection of the pulling section with the cable on the lifeline system through a hook or other connecting piece.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) By setting an alarm mechanism and a trigger mechanism, when a person falls and generates a huge impact force, the limit nut is easily trapped between the shock absorbing unit and the sliding rod under the huge instantaneous impact force, causing the first contact piece to contact the second contact piece, the circuit is turned on, and the alarm mechanism is energized to send an alarm signal, warning the inspection personnel to stop using the anti-fall device and carry out maintenance, intuitively reflecting the shock absorption failure state of the anti-fall system, and warning the operator that the anti-fall device has a safety risk, thereby increasing the risk warning function of the anti-fall equipment, reducing the risk of climbing and falling of the inspection personnel, and reducing the inspection and maintenance cost of the anti-fall system;

[0034] (2) By setting the first contact piece and the second contact piece in a circular ring shape, the contact area between the first contact piece and the second contact piece is increased, thereby improving the accuracy of conduction between the two. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is an overall schematic diagram of an embodiment of the present invention;

[0036] Figure 2 This is a cross-sectional schematic diagram of the present invention for showing the structure inside the active cavity cut along the central axis of the support member;

[0037] Figure 3 A cross-sectional schematic diagram showing the positional relationship between the sliding rod and the insulating layer;

[0038] Figure 4 A structural schematic diagram showing the positions of the first energized spring piece and the second energized spring piece of the present invention;

[0039] Figure 5 A simplified schematic diagram showing the connection relationship between the sound and light alarm device, wires and trigger mechanism.

[0040] Figure numerals: 1. Support member; 01. Movable cavity; 02. Through groove; 03. Connecting gap; 2. Connecting member; 21. Connecting rod; 22. First limiting ring; 3. Traction member; 31. Pulling section; 32. Sliding rod; 33. Limiting member; 4. Sound and light alarm device; 41. Fixed seat; 42. Light-emitting member; 5. Trigger mechanism; 51. First contact piece; 52. Second contact piece; 6. Shock-absorbing unit; 7. Insulating layer; 8. Pin; 9. Second limiting ring; 10. First energized spring piece; 11. Second energized spring piece. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0042] Combination Figure 1 and Figure 2 A fall prevention and shock absorption device for a high altitude lifeline system comprises a shock absorber body, the shock absorber body comprises a support 1, a connecting component 2, a traction component 3, an alarm mechanism, a trigger mechanism 5 and a shock absorbing unit 6, the support 1 is provided with an active cavity 01, the shock absorbing unit 6, the trigger mechanism 5 and the alarm mechanism are all in the active cavity 01, the connecting component 2 is used to install and fix the shock absorber body, the connecting component 2 is located on one side of the support 1 and is fixedly connected to the support 1, the traction component 3 is used to drive the shock absorbing unit 6 to reciprocate and extend in the active cavity 01, the traction component 3 is located on the other side of the support 1 and is movably connected to the support 1, in the lifeline system, the traction component 3 is connected to the cable in the lifeline system, when a person falls, the impact force generated during the fall pulls the cable, driving the shock absorbing unit 6 to be compressed, the elastic potential energy generated by the shock absorbing unit 6 absorbs part of the impact force, and achieves a buffering effect, according to the European standard EN795-C, the impact force generated during the fall is reduced to less than 6000N, protecting the safety of the human body.

[0043] like Figure 2 As shown, in this embodiment, the support member 1 is sleeve-shaped as a whole, and the movable cavity 01 is opened inside the support member 1 along the central axis of the support member 1. The traction component 3 includes a pulling section 31, a sliding rod 32 and a limiting member 33. The sliding rod 32 is configured as a bolt, and the end of the sliding rod 32 without a head is slidably penetrated into the movable cavity 01 on a bottom wall of the support member 1, and this end of the sliding rod 32 is fixedly connected to the limiting member 33. In this embodiment, the limiting member 33 is configured as a limiting nut threadedly connected to the sliding rod 32. The sliding rod 32 is made of metal material, and the outer wall of the sliding rod 32 is covered with an insulating layer 7 (such as Figure 3 As shown), the insulating layer 7 is set to be a thin layer of rubber or similar insulating material.

[0044] The other end of the sliding rod 32 extends out of the support member 1 and is fixedly connected to the pulling section 31. Specifically, the pulling section 31 is in a "U" shape as a whole. Pins 8 are passed through both ends of the pulling section 31. Both ends of the pin 8 extend out of the pulling section 31. Both ends of the pin 8 are fixedly connected with a second limiting ring 9. The second limiting ring 9 prevents the pin 8 from separating from the pulling section 31. A sliding hole is provided on the side of the pulling section 31 away from the pin 8. The size of the sliding hole is smaller than the size of the head of the sliding rod 32. The end of the sliding rod 32 with the head slides in the sliding hole and the head of the bolt can abut against the surface of the pulling section 31.

[0045] Combination Figure 1 and Figure 2 The connecting component 2 includes a connecting rod 21 and a first limiting ring 22. The connecting rod 21 is passed through the support member 1 and both ends of the connecting rod 21 extend out of the support member 1. Two first limiting rings 22 are provided and are respectively fixedly connected to both ends of the connecting rod 21. The first limiting rings 22 prevent the connecting rod 21 from being separated from the connecting rod 21. The support member 1 is provided with a through groove 02 connected to the movable cavity 01 at the connecting rod 21 to form an opening. The through groove 02 extends to the support member 1 to form a connecting slit 03 that is convenient for hanging a hook. Two connecting slits 03 are respectively provided on the support member 1, and the two connecting slits 03 are evenly spaced to connect the support member 1 as a whole with other components on the lifeline system through a hook or other connecting member.

[0046] The shock absorbing unit 6 is made of elastic material, such as elastic polyurethane, and is cylindrical in shape. The shock absorbing unit 6 is provided with a through hole along its central axis to match the sliding rod 32. The maximum outer diameter of the above-mentioned limiter 33, i.e., the limit nut, is greater than the inner diameter of the through hole. The shock absorbing unit 6 is slidably arranged on the sliding rod 32, so that the shock absorbing unit 6 abuts against the limiter 33 and the inner wall of the support member 1 respectively.

[0047] like Figure 4 As shown, the trigger mechanism 5 includes a first contact piece 51 connected to the limit nut and a second contact piece 52 fixedly connected to the shock absorbing unit 6, and the first contact piece 51 and the second contact piece 52 are both electrically connected to the alarm mechanism. Specifically, the first contact piece 51 is annular, and the first contact piece 51 is located on the side of the limit nut facing the shock absorbing unit 6, and the first contact piece 51 is coaxially arranged with the limit nut. The first contact piece 51 extends between the shock absorbing unit 6 and the sliding rod 32, and the first energized spring piece 10 is integrally connected to the first contact piece 51, and the first energized spring piece 10 is very thin, and the first energized spring piece 10 is located outside the shock absorbing unit 6. The second contact piece 52 is also annular, and the second contact piece 52 is located between the shock absorbing unit 6 and the sliding rod 32, and the second contact piece 52 is fixedly connected to the inner wall of the shock absorbing unit 6 at the through hole. The second contact piece 52 is integrally connected to the second energized spring piece 11, and the second energized spring piece 11 is located outside the shock absorbing unit 6, and the second energized spring piece 11 is very thin.

[0048] Preferably, in this embodiment, when the shock absorbing unit 6 is not compressed, that is, when the shock absorbing unit 6 is respectively in contact with the limiting nut and the inner wall of the support member 1, it is set to the initial state, the first contact piece 51 extends between the shock absorbing unit 6 and the sliding rod 32, the second contact piece 52 is in the through hole, and the second contact piece 52 is at the end position of the shock absorbing unit 6, away from the limiting nut.

[0049] The first contact piece 51 and the second contact piece 52 are made of copper with good conductivity, and the surfaces of the first contact piece 51 and the second contact piece 52 are plated with a layer of silver to improve their conductivity. The first energizing spring piece 10 and the second energizing spring piece 11 are also made of copper, which is thin and easy to deform.

[0050] like Figure 2 As shown, the alarm mechanism includes an audible and visual alarm device 4, which includes a fixing seat 41 fixedly installed in the active cavity 01 and a light-emitting member 42 fixedly connected to the fixing seat 41. The audible and visual alarm device 4 is arranged close to the connecting rod 21, and the light-emitting member 42 is arranged toward the opening, so that the brightness of the light-emitting member 42 can be emitted from the opening at the connecting rod 21, thereby facilitating the detection personnel to see the alarm signal in time. Figure 5 As shown, in this embodiment, the sound and light alarm device 4 can adopt a flashing electronic alarm such as the VEXG brand model BJ-3. The sound and light alarm device 4 is electrically connected to two conductive wires. The end of the first energized spring 10 away from the first contact piece 51 and the end of the second energized spring 11 away from the second contact piece 52 are both arranged close to the sound and light alarm device 4, and the ends of the two conductive wires away from the sound and light alarm device 4 are respectively wound around the first energized spring 10 and the second energized spring 11.

[0051] When a person falls and an impact force is generated, the cable pulls the pulling section 31 to move, causing the sliding rod 32 to slide away from the support member 1, compressing the limit nut and the shock absorbing unit 6 between the support member 1. When the weight of the human body is too large and the height of the human body falling is high, an instantaneous huge impact force will be generated. Under the action of the huge instantaneous impact force, the limit nut is easily trapped from the through hole between the shock absorbing unit 6 and the sliding rod 32. When the limit nut gradually sinks into the through hole, the first contact piece 51 contacts the second contact piece 52, the circuit is turned on, and the sound and light alarm device 4 is energized to send out an alarm signal, that is, a high-decibel alarm sound is emitted, and a red light flashing alarm is emitted at the same time, warning the inspection personnel to stop using the shock absorbing device for maintenance.

[0052] The anti-fall shock absorbing device in this embodiment can be used not only for shock absorbing alarm of safety lifeline, but also for shock absorbing alarm of other devices such as anti-fall safety anchor point, anti-fall brake, anti-fall self-locking device, etc.

[0053] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A fall prevention and shock absorption device for a high altitude lifeline system, comprising a shock absorber body, characterized in that: The shock absorber body comprises a support member (1), a connecting member (2), a traction member (3), an alarm mechanism, a trigger mechanism (5) and a shock absorbing unit (6). The support member (1) is provided with an active cavity (01), and the shock absorbing unit (6), the trigger mechanism (5) and the alarm mechanism are all located in the active cavity (01); The connecting component (2) is used to install and fix the shock absorber body, is located on one side of the support member (1) and is fixedly connected to the support member (1); The traction component (3) is used to drive the shock absorbing unit (6) to reciprocate and extend in the movable cavity (01), is located on the other side of the support member (1) and is movably connected to the support member (1), and comprises a pulling section (31), a sliding rod (32) and a limiting member (33); one end of the sliding rod (32) is slidably inserted into the movable cavity (01) and is fixedly connected to the limiting member (33); the other end of the sliding rod (32) extends out of the support member (1) and is fixedly connected to the pulling section (31); the shock absorbing unit (6) is slidably inserted into the sliding rod (32); The trigger mechanism (5) comprises a first contact piece (51) connected to the limiter (33) and a second contact piece (52) fixedly connected to the shock absorbing unit (6), and the first contact piece (51) and the second contact piece (52) are both electrically connected to the alarm mechanism; When the shock absorbing unit (6) is compressed and the limiting member (33) is located between the shock absorbing unit (6) and the sliding rod (32), the first contact piece (51) contacts the second contact piece (52), and the alarm mechanism is powered on to send out an alarm signal; The first contact piece (51) is located on the side of the limiting member (33) facing the shock absorbing unit (6), the shock absorbing unit (6) is provided with a through hole adapted to the sliding rod (32), the second contact piece (52) is located between the shock absorbing unit (6) and the sliding rod (32), and the second contact piece (52) is fixedly connected to the inner wall of the shock absorbing unit (6) at the through hole; The limiting member (33) comprises a limiting nut threadedly connected to the sliding rod (32); the first contact piece (51) is annular; the first contact piece (51) and the limiting nut are coaxially arranged; the first contact piece (51) extends between the shock absorbing unit (6) and the sliding rod (32); the first contact piece (51) is integrally connected with a first energized spring piece (10); the first energized spring piece (10) is located outside the shock absorbing unit (6); The second contact piece (52) is in the shape of a ring, and a second energized elastic piece (11) is integrally connected to the second contact piece (52), and the second energized elastic piece (11) is located outside the shock absorbing unit (6); The end of the first energized elastic sheet (10) away from the first contact sheet (51) and the end of the second energized elastic sheet (11) away from the second contact sheet (52) are both arranged close to the alarm mechanism; The connecting component (2) comprises a connecting rod (21) and a first limiting ring (22); the connecting rod (21) is passed through the supporting member (1) and both ends of the connecting rod (21) extend out of the supporting member (1); two first limiting rings (22) are provided and are respectively fixedly connected to both ends of the connecting rod (21); The support member (1) is provided with a through groove (02) communicating with the active cavity (01) at the connection rod (21) to form an opening, and the through groove (02) extends to the support member (1) to form two spaced connection slits (03); The alarm mechanism comprises an audible and visual alarm device (4), the audible and visual alarm device (4) comprising a fixing seat (41) fixedly mounted in the active cavity (01) and a light emitting member (42) fixedly connected to the fixing seat (41), the light emitting member (42) being arranged toward the opening; The sound and light alarm device (4) is arranged close to the connecting rod (21); The pulling section (31) is in a "U" shape as a whole, and pins (8) are inserted through both ends of the pulling section (31). Both ends of the pin (8) extend out of the pulling section (31), and both ends of the pin (8) are fixedly connected to a second limiting ring (9).

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