Immersed tube foundation bed desilting platform convenient for rapid construction

Abstract

The utility model provides an immersed tube foundation bed desilting platform convenient for rapid construction, which comprises a self-floating platform, a longitudinal moving trolley and a transverse moving trolley, a first moon pool is arranged in the middle of the self-floating platform, the longitudinal moving trolley is arranged in the first moon pool in a sliding manner, the transverse moving trolley is connected with the lower part of the longitudinal moving trolley in a sliding manner, and the moving directions of the transverse moving trolley and the longitudinal moving trolley are vertical. The dredging pipe is arranged in the transverse moving trolley in a penetrating mode and connected with the top of the longitudinal moving trolley through a connecting rope, the adjusting devices are arranged on the two sides of the longitudinal moving trolley in parallel respectively and connected with the adapters through the connecting ropes, the adapters are connected with the self-floating platform through first pull ropes, and the adjusting devices are used for adjusting the fixing positions and tensioning force of the connecting ropes. The dredging platform is compact in structure and simple in design, and stability and smoothness of the dredging platform in the moving process can be greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of underwater engineering construction, in particular to a submerged tube bed dredging platform which is convenient for rapid construction. Background Art

[0002] An immersed tube tunnel is an underwater tunnel built by floating several prefabricated sections to the sea (river) site and installing them one by one in a dredged foundation trench. In order to avoid local high points on the foundation and ensure that the bottom plate of the immersed tube is evenly stressed, a gravel foundation bed with high flatness requirements must be laid in the immersed tube foundation trench. It takes several days from the beginning of laying the foundation bed to installing the pipe section. This time may be further increased due to the leveling, floating progress and other factors. Since the sand content in nearshore waters is usually high, the siltation of the foundation bed will increase under the influence of multiple factors such as water flow velocity, changes in sand content, and water disturbance, and even cause silt accumulation. The deposited silt will have an adverse effect on the construction of the immersed tube and the stress of the structure. In order to prevent silt from affecting the immersed tube tunnel, the silt-accumulated foundation bed must be dredged. Chinese patent document CN 113833044 A records a high-precision environmentally friendly immersed tube bed dredging platform. Since the water surface is a dynamic supporting surface, the dredging platform shakes when it moves and positions on the water surface. In the process of adjusting the dredging head by the winch, the position and height of the pull rope relative to the winch change, so the force direction applied to the longitudinal movement trolley always changes, and the overall movement will be not smooth. There are defects in use and need to be improved. Utility Model Content

[0003] The utility model provides a submerged tube base bed dredging platform which is convenient for rapid construction, and solves the problem that the force direction of the dredging platform always changes during the movement process of adjusting the dredging head, resulting in unsmooth movement.

[0004] In order to solve the above technical problems, the technical solution adopted by the utility model is: a submerged tube base bed dredging platform which is convenient for rapid construction, including a self-floating platform, a longitudinal moving trolley and a transverse moving trolley. A first moon pool is provided in the middle of the self-floating platform, the longitudinal moving trolley is slidably arranged in the first moon pool, the transverse moving trolley and the lower part of the longitudinal moving trolley are slidably connected, the moving directions of the transverse moving trolley and the longitudinal moving trolley are perpendicular, the dredging pipe is passed through the transverse moving trolley, the dredging pipe is connected to the top of the longitudinal moving trolley through a connecting rope, and adjustment devices are respectively provided in parallel on both sides of the longitudinal moving trolley, the adjustment device is connected to the adapter through a connecting rope, the adapter is connected to the self-floating platform through a first pull rope, and the adjustment device is used to adjust the fixed position and tension of the connecting rope.

[0005] In a preferred solution, the self-floating platform includes longitudinal tubes arranged in parallel on both sides of the first moon pool, the two sides of the longitudinal tubes are respectively connected by a plurality of transverse tubes, and the tops of the longitudinal tubes and the transverse tubes are connected by a support plate.

[0006] In a preferred solution, longitudinal winches are respectively provided on both sides of the first moon pool, the longitudinal winches are connected to the first pull rope, and mooring winches are symmetrically provided on both sides of the longitudinal winches, and the mooring winches are used to adjust the position of the self-floating platform and fix it.

[0007] In the preferred solution, two longitudinal tracks are provided in parallel on the inner side of the first moon pool. The longitudinal moving trolley includes a base, which is slidably connected to the longitudinal tracks through rollers. The transverse moving trolley is slidably connected to the base. The transverse moving trolley is used to adjust the position of the dredging pipe. A second moon pool is provided through the base, and the dredging pipe is provided in the second moon pool.

[0008] In the preferred solution, a gantry is provided on the upper side of the base, a hanging beam is provided on the gantry, a lifting hoist is slidably connected to the hanging beam, the lifting hoist is connected to the dredging pipe through a second pull rope, a dredging head is provided at the lower part of the dredging pipe, and a detachable mud discharge pipe is provided at the upper part of the dredging pipe.

[0009] In the preferred scheme, the adjustment device includes a T-shaped plate and a movable plate, the T-shaped plate is connected to the base, a bolt is rotatably provided on the movable plate, the bolt is passed through the movable plate, the bolt and the T-shaped plate are threadedly connected, a guide rod is provided at the lower part of the movable plate, the guide rod is passed through the T-shaped plate, a locking ring is provided on the outer side of the movable plate, and the connecting rope is connected through a hook and the locking ring.

[0010] In the preferred embodiment, a first threaded hole and a first through hole are penetrated on the T-shaped plate, a third through hole is penetrated on the bolt, an axial rod is inserted in the third through hole, and at least two nuts are provided on the bolt. The movable plate includes a vertical plate and a C-shaped plate, the C-shaped plate and the base are slidably connected, a second through hole is penetrated on the vertical plate, the guide rod is fixedly arranged on a side of the vertical plate close to the T-shaped plate, a second threaded hole is provided on the upper side of the locking ring, and a screw for limiting the hook is provided in the second threaded hole.

[0011] In a preferred embodiment, the adapter includes two mounting plates arranged in parallel, the two mounting plates are connected by a cylinder, a ring groove is provided in the middle of the cylinder, a rounded corner is provided between the ring groove and the cylinder, and a mark is also provided on the outside of the mounting plate, and the connecting rope and the first pull rope are respectively wrapped around the ring groove.

[0012] In the preferred scheme, a follower pulley and an adaptive pulley are sequentially provided on the side of the longitudinal winch facing the longitudinal transport trolley, the follower pulley is provided with a first roller, the adaptive pulley is provided with two second rollers, a constraint channel is formed between the two second rollers, the first pull rope is passed through the constraint channel, and the first pull rope is attached to the lower part of the first roller.

[0013] In a preferred solution, two third threaded holes and a fourth threaded hole are parallelly arranged on the support plate, the follower pulley comprises a first bracket, the first roller is rotatably arranged on the first bracket, a disc is arranged at the lower part of the first bracket, a waist-shaped groove is penetrated on the disc, and the waist-shaped groove is connected to the third threaded hole through a locking pin;

[0014] The adaptive pulley includes a second bracket and a base plate. The second roller is rotatably arranged on the second bracket. A through hole is penetrated on the base plate. A screw is passed through the through hole. The screw is threadedly connected to the fourth threaded hole. Two springs are sleeved on the screw. The two springs are respectively located on both sides of the base plate. The screw is connected to the base plate through a locking sleeve.

[0015] The beneficial effects of the utility model are as follows: by arranging an adjustment device on the longitudinal movement trolley, it is ensured that during the initial installation, the connecting ropes on both sides of the longitudinal movement trolley are symmetrically stressed and have stable tension, so that the installation position of the adapter is on the moving axis of the longitudinal movement trolley, the overall force is balanced, and the movement is smoother. At the same time, in order to further adjust the direction of the first pull rope to be relatively stable, a follower pulley and an adaptive pulley are installed on the support plate of the self-floating platform. The direction of the first pull rope is adjusted by the follower pulley, and the first pull rope is controlled in the height direction by the adaptive pulley. The overall control is more precise, thereby ensuring that the longitudinal movement of the trolley is smoother and has good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The utility model is further described below in conjunction with the accompanying drawings and embodiments:

[0017] Figure 1 It is a top view schematic diagram of the utility model;

[0018] Figure 2 It is a front view schematic diagram of the utility model;

[0019] Figure 3 It is a right side schematic diagram of the utility model;

[0020] Figure 4 It is a schematic diagram of the structure of the adjustment device installation adapter of the utility model;

[0021] Figure 5 yes Figure 4 A top view schematic diagram of

[0022] Figure 6 yes Figure 4 A front view schematic diagram of

[0023] Figure 7 yes Figure 4 Schematic diagram of the explosion structure Figure 1 ;

[0024] Figure 8 yes Figure 4 Schematic diagram of the explosion structure Figure 2 ;

[0025] Fig. 9 yes Figure 8 A magnified schematic diagram of point A;

[0026] Fig.10 yes Figure 8 An enlarged schematic diagram of point B;

[0027] Fig.11 yes Figure 8 An enlarged schematic diagram of point C;

[0028] Fig.12 yes Figure 8 Schematic diagram of the adapter;

[0029] Fig.13 yes Figure 8 Schematic diagram of the adaptive scroll wheel.

[0030] In the figure: self-floating platform 1; longitudinal tube 101; transverse tube 102; first moon pool 103; support plate 104; third threaded hole 105; fourth threaded hole 106; mooring winch 2; longitudinal track 3; adjustment device 4; T-plate 401; moving plate 402; first threaded hole 403; first through hole 404; bolt 405; shaft rod 406; nut 407; vertical plate 408; C-plate 409; second through hole 410; guide rod 411; locking ring 412; second threaded hole 413; screw 414; third through hole 415; adapter 5; mounting plate 501; cylinder 502; annular groove 503; fillet 504; mark 505; connecting rope 6; longitudinal winch Car 7; longitudinal moving trolley 8; roller 801; base 802; second moon pool 803; gantry 804; lifting beam 805; lifting hoist 9; transverse moving trolley 10; generator set 11; air compressor unit 12; dredging pipe 13; dredging head 14; mud discharge pipe 15; hook 16; follow-up pulley 17; first bracket 1701; first roller 1702; disc 1703; waist groove 1704; locking pin 1705; adaptive pulley 18; second bracket 1801; bottom plate 1802; second roller 1803; screw 1804; spring 1805; locking sleeve 1806; through hole 1807; constraint channel 1808; first pull rope 19; second pull rope 20. DETAILED DESCRIPTION

[0031] like Figure 1-6A submerged tube bed dredging platform which is convenient for rapid construction is disclosed, comprising a self-floating platform 1, a longitudinal moving trolley 8 and a transverse moving trolley 10. A first moon pool 103 is provided in the middle of the self-floating platform 1. The longitudinal moving trolley 8 is slidably arranged in the first moon pool 103. The transverse moving trolley 10 is slidably connected to the lower part of the longitudinal moving trolley 8. The moving directions of the transverse moving trolley 10 and the longitudinal moving trolley 8 are perpendicular. A dredging pipe 13 is passed through the transverse moving trolley 10. The dredging pipe 13 is connected to the top of the longitudinal moving trolley 8 through a connecting rope 6. Adjustment devices 4 are respectively provided in parallel on both sides of the longitudinal moving trolley 8. The adjustment device 4 is connected to the adapter 5 through the connecting rope 6. The adapter 5 is connected to the self-floating platform 1 through a first pull rope 19. The adjustment device 4 is used to adjust the fixed position and tension of the connecting rope 6. A generator set 11 and an air compressor set 12 are also provided on the self-floating platform 1. The generator set 11 provides power supply for the mooring winch 2, the longitudinal winch 7, the hoisting hoist 9 and the transverse trolley 10 and other electrical components. The air compressor set 12 cooperates with the dredging head 14 on the dredging pipe 13 to clean the silt on the riverbed through negative pressure. By arranging the adjustment device 4 on the longitudinal trolley 8, during installation, the position of the connecting rope 6 can be changed by changing the position of the adjustment device 4 to ensure a good fixing effect. At the same time, the tension is appropriate, and the force of the connecting rope 6 on both sides is symmetrical, which is convenient for moving on the self-floating platform 1 more smoothly. The adapter 5 is used as a locking component for the connecting rope 6 on both sides. When it is installed, it can be closer to the moving center axis of the longitudinal trolley 8. The overall force conversion is more reasonable, which reduces the possibility of failure and breakage during use and prolongs the service life.

[0032] In a preferred solution, the self-floating platform 1 includes longitudinal tubes 101 arranged in parallel on both sides of the first moon pool 103, the two sides of the longitudinal tubes 101 are respectively connected by a plurality of transverse tubes 102, and the tops of the longitudinal tubes 101 and the transverse tubes 102 are connected by a support plate 104. This structure has good overall rigidity, convenient manufacturing and installation, reasonable weight control, and stable buoyancy.

[0033] In the preferred solution, longitudinal winches 7 are respectively provided on both sides of the first moon pool 103, and the longitudinal winches 7 are connected to the first pull rope 19. Mooring winches 2 are symmetrically provided on both sides of the longitudinal winch 7, and the mooring winches 2 are used to adjust the position and fix the self-floating platform 1. The dredging pipe 13 can be adjusted in both the horizontal and vertical directions by the longitudinal trolley 8 and the transverse trolley 10, so that the overall dredging work can be completed efficiently.

[0034] In the preferred solution, two longitudinal tracks 3 are arranged in parallel inside the first moon pool 103, the longitudinal moving trolley 8 comprises a base 802, the base 802 is slidably connected to the longitudinal track 3 via a roller 801, the transverse moving trolley 10 is slidably connected to the base 802, the transverse moving trolley 10 is used to adjust the position of the dredging pipe 13, the base 802 is penetrated by a second moon pool 803, and the dredging pipe 13 is arranged in the second moon pool 803. With this structure, the overall fixing is convenient, the operation is simple, the first moon pool 103 can be fully covered, the dredging is orderly, and the dredging effect is good.

[0035] In the preferred solution, a door frame 804 is provided on the upper side of the base 802, a hanging beam 805 is provided on the door frame 804, a lifting hoist 9 is slidably connected to the hanging beam 805, the lifting hoist 9 is connected to the dredging pipe 13 through the second pull rope 20, a dredging head 14 is provided at the lower part of the dredging pipe 13, and a sludge discharge pipe 15 is detachably provided at the upper part of the dredging pipe 13. With this structure, the dredging head 13 can be adjusted in the height direction, and installation and disassembly are convenient.

[0036] like Figure 7-10 In the preferred solution, the adjustment device 4 includes a T-shaped plate 401 and a movable plate 402, the T-shaped plate 401 is connected to the base 802, a bolt 405 is rotatably provided on the movable plate 402, the bolt 405 is inserted into the movable plate 402, the bolt 405 is threadedly connected to the T-shaped plate 401, a guide rod 411 is provided at the lower part of the movable plate 402, the guide rod 411 is inserted on the T-shaped plate 401, a locking ring 412 is provided on the outer side of the movable plate 402, and the connecting rope 6 is connected to the locking ring 412 through the hook 16. With this structure, the position of the movable plate 402 can be changed by the bolt 405, so that the connecting rope 6 is driven to move by the locking ring 412 and the hook 16, ensuring that the directions of the connecting ropes 6 on both sides are symmetrical and the tension is stable.

[0037] In the preferred solution, the T-shaped plate 401 is provided with a first threaded hole 403 and a first through hole 404, the bolt 405 is provided with a third through hole 415, the third through hole 415 is inserted with a shaft 406, and the bolt 405 is provided with at least two nuts 407, the movable plate 402 includes a vertical plate 408 and a C-shaped plate 409, the C-shaped plate 409 is slidably connected to the base 802, the vertical plate 408 is provided with a second through hole 410, the guide rod 411 is fixedly arranged on the side of the vertical plate 408 close to the T-shaped plate 401, the upper side of the locking ring 412 is provided with a second threaded hole 413, and the second threaded hole 413 is provided with a screw 414 for limiting the hook 16. With this structure, the installation and disassembly are convenient, the movable plate 402 is more fully attached to the bottom plate 802, the moving precision is high, the locking quality is better, and the screw 414 can also prevent the hook 16 from easily falling off and sliding out of the locking ring 412, and the overall safety protection effect is better.

[0038] like Fig.12In the preferred solution, the adapter 5 includes two parallel mounting plates 501, the two mounting plates 501 are connected by a cylinder 502, an annular groove 503 is provided in the middle of the cylinder 502, a fillet 504 is provided between the annular groove 503 and the cylinder 502, a mark 505 is also provided on the outer side of the mounting plate 501, and the connecting rope 6 and the first pull rope 19 are respectively wound on the annular groove 503. When in use, the connecting rope 6 and the first pull rope 19 fit on the annular groove 503, and they are slidably connected to the slide groove 503, so that the angle can be finely adjusted within a certain range, and the overall force is more sufficient.

[0039] like Fig.11 and 13 In the preferred solution, the longitudinal winch 7 is provided with a follower pulley 17 and an adaptive pulley 18 in sequence on the side facing the longitudinal trolley 8, the follower pulley 17 is provided with a first roller 1702, the adaptive pulley 18 is provided with two second rollers 1803, a constraint channel 1808 is formed between the two second rollers 1803, the first pull rope 19 is passed through the constraint channel 1808, and the first pull rope 19 is attached to the lower part of the first roller 1702. With this structure, the direction of the first pull rope 19 is adjusted by the follower pulley 17, and the first pull rope 19 is controlled in the height direction by the adaptive pulley 18, and the overall control is more precise, thereby ensuring that the longitudinal trolley moves more smoothly. When the first pull rope 19 drives the longitudinal trolley 8 to move, the adapter 8 can move along the central axis of the longitudinal trolley 8 and the force is stable.

[0040] In a preferred embodiment, two third threaded holes 105 and a fourth threaded hole 106 are parallelly arranged on the support plate 104, the follower pulley 17 includes a first bracket 1701, a first roller 1702 is rotatably arranged on the first bracket 1701, a disc 1703 is arranged at the lower part of the first bracket 1701, a waist groove 1704 is penetrated on the disc 1703, and the waist groove 1704 is connected to the third threaded hole 105 through a locking pin 1705;

[0041] The adaptive pulley 18 includes a second bracket 1801 and a bottom plate 1802, a second roller 1803 is rotatably arranged on the second bracket 1801, a through hole 1807 is penetrated on the bottom plate 1802, a screw 1804 is passed through the through hole 1807, the screw 1804 is threadedly connected with the fourth threaded hole 106, two springs 1805 are sleeved on the screw 1804, the two springs 1805 are respectively located on both sides of the bottom plate 1802, and the screw 1804 is connected to the bottom plate 1802 through a locking sleeve 1806. With this structure, the overall installation and disassembly is convenient and the use effect is good. Arc grooves are arranged on the first roller 1702 and the second roller 1803, and the first pull rope 19 fits in the arc groove, so that the overall restraint effect is better.

[0042] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A submerged tube bed desilting platform that is easy to construct quickly, characterized by: The invention comprises a self-floating platform (1), a longitudinal moving trolley (8) and a transverse moving trolley (10). A first moon pool (103) is provided in the middle of the self-floating platform (1). The longitudinal moving trolley (8) is slidably arranged in the first moon pool (103). The transverse moving trolley (10) is slidably connected to the lower part of the longitudinal moving trolley (8). The moving directions of the transverse moving trolley (10) and the longitudinal moving trolley (8) are perpendicular. A dredging pipe (13) is passed through the transverse moving trolley (10). The dredging pipe (13) is connected to the top of the longitudinal moving trolley (8) through a connecting rope (6). Adjustment devices (4) are respectively provided in parallel on both sides of the longitudinal moving trolley (8). The adjustment device (4) is connected to an adapter (5) through a connecting rope (6). The adapter (5) is connected to the self-floating platform (1) through a first pull rope (19). The adjustment device (4) is used to adjust the fixing position and tension of the connecting rope (6).

2. According to claim 1, a submerged tube bed desilting platform that is convenient for rapid construction is characterized by: The self-floating platform (1) comprises longitudinal pipes (101) arranged in parallel on both sides of a first moon pool (103), the two sides of the longitudinal pipes (101) are respectively connected by a plurality of transverse pipes (102), and the tops of the longitudinal pipes (101) and the transverse pipes (102) are connected by a support plate (104).

3. According to claim 2, a submerged tube bed desilting platform that is convenient for rapid construction is characterized by: A longitudinal winch (7) is provided on both sides of the first moon pool (103), the longitudinal winch (7) is connected to the first pull rope (19), and mooring winches (2) are symmetrically provided on both sides of the longitudinal winch (7), and the mooring winches (2) are used to adjust the position of the self-floating platform (1) and fix it.

4. According to claim 1, a submerged tube bed desilting platform that is convenient for rapid construction is characterized by: Two longitudinal tracks (3) are arranged in parallel on the inner side of the first moon pool (103); the longitudinal moving trolley (8) comprises a base (802); the base (802) is slidably connected to the longitudinal tracks (3) via rollers (801); the transverse moving trolley (10) is slidably connected to the base (802); the transverse moving trolley (10) is used to adjust the position of the dredging pipe (13); a second moon pool (803) is arranged through the base (802); and the dredging pipe (13) is arranged in the second moon pool (803).

5. According to claim 4, a submerged tube bed desilting platform that is convenient for rapid construction is characterized by: A door frame (804) is provided on the upper side of the base (802), a hanging beam (805) is provided on the door frame (804), a lifting hoist (9) is slidably connected to the hanging beam (805), the lifting hoist (9) is connected to the dredging pipe (13) via a second pull rope (20), a dredging head (14) is provided at the lower part of the dredging pipe (13), and a sludge discharge pipe (15) is detachably provided at the upper part of the dredging pipe (13).

6. The immersed tube bed desilting platform for rapid construction according to claim 4 is characterized by: The adjustment device (4) comprises a T-shaped plate (401) and a movable plate (402), wherein the T-shaped plate (401) is connected to a base (802), a bolt (405) is rotatably provided on the movable plate (402), the bolt (405) is inserted into the movable plate (402), the bolt (405) and the T-shaped plate (401) are threadedly connected, a guide rod (411) is provided at the lower part of the movable plate (402), the guide rod (411) is inserted into the T-shaped plate (401), a locking ring (412) is provided on the outer side of the movable plate (402), and a connecting rope (6) is connected to the locking ring (412) via a hook (16).

7. The immersed tube bed desilting platform for rapid construction according to claim 6 is characterized by: The T-shaped plate (401) is provided with a first threaded hole (403) and a first through hole (404) through it, the bolt (405) is provided with a third through hole (415) through it, a shaft (406) is inserted into the third through hole (415), and at least two nuts (407) are provided on the bolt (405). The movable plate (402) comprises a vertical plate (408) and a C-shaped plate (409), the C-shaped plate (409) and the base (802) are slidably connected, a second through hole (410) is provided through it on the vertical plate (408), a guide rod (411) is fixedly arranged on a side of the vertical plate (408) close to the T-shaped plate (401), a second threaded hole (413) is provided on the upper side of the locking ring (412), and a screw (414) for limiting the hook (16) is provided in the second threaded hole (413).

8. The immersed tube bed desilting platform for rapid construction according to claim 1 is characterized by: The adapter (5) comprises two mounting plates (501) arranged in parallel, the two mounting plates (501) being connected via a cylinder (502), a ring groove (503) being provided in the middle of the cylinder (502), a fillet (504) being provided between the ring groove (503) and the cylinder (502), a mark (505) being provided on the outer side of the mounting plates (501), and a connecting rope (6) and a first pull rope (19) being respectively wound around the ring groove (503).

9. The immersed tube bed desilting platform for rapid construction according to claim 3 is characterized by: A follower pulley (17) and an adaptive pulley (18) are sequentially arranged on the side of the longitudinal moving winch (7) facing the longitudinal moving trolley (8); a first roller (1702) is arranged on the follower pulley (17); two second rollers (1803) are arranged on the adaptive pulley (18); a constraint channel (1808) is formed between the two second rollers (1803); a first pull rope (19) is passed through the constraint channel (1808); and the first pull rope (19) is attached to the lower part of the first roller (1702).

10. The immersed tube bed desilting platform for rapid construction according to claim 9, characterized in that: Two third threaded holes (105) and a fourth threaded hole (106) are arranged in parallel on the support plate (104); the follower pulley (17) comprises a first bracket (1701); a first roller (1702) is rotatably arranged on the first bracket (1701); a disc (1703) is arranged at the lower part of the first bracket (1701); a waist-shaped groove (1704) is penetrated through the disc (1703); and the waist-shaped groove (1704) is connected to the third threaded hole (105) via a locking pin (1705); The adaptive pulley (18) comprises a second bracket (1801) and a bottom plate (1802); a second roller (1803) is rotatably arranged on the second bracket (1801); a through hole (1807) is provided through the bottom plate (1802); a screw rod (1804) is provided through the through hole (1807); the screw rod (1804) is threadedly connected to a fourth threaded hole (106); two springs (1805) are sleeved on the screw rod (1804); the two springs (1805) are respectively located on two sides of the bottom plate (1802); and the screw rod (1804) is connected to the bottom plate (1802) via a locking sleeve (1806).

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