Unit a repair large component horizontal adjustment support system

Abstract

A large component horizontal adjustment support system for unit A repair, comprising a hydraulic support device, the hydraulic support device comprising a support pier, a hydraulic jack, a pressure bearing disc, a pressure sensor and a displacement sensor, the hydraulic jack being arranged on the support pier, the pressure sensor being arranged on a piston column of the hydraulic jack through an angle adjustment mechanism, and the pressure bearing disc being connected with a measuring end of the pressure sensor; an electronic level, the electronic level being arranged on the large maintenance component. The height of the pressure bearing disc of each hydraulic support device is adjusted through a control device, and in the case that the pressure bearing disc of each hydraulic support device is forced and the force deviation is within a threshold range, the large maintenance component is adjusted to a horizontal state according to a measurement signal fed back to the control device by the electronic level, so that the horizontal support precision of the large maintenance component during the unit A repair process can be greatly improved.

Description

Technical Field

[0001] This utility model belongs to the technical field of hydroelectric generator set maintenance equipment, and relates to a horizontal adjustment support system for large components of generator set A-level maintenance. Background Technology

[0002] Unit A overhaul is a comprehensive disassembly and inspection of all components of a hydroelectric generator set. This includes cleaning internal scale, oil, and dust, lubricating and rust-preventing key components, conducting comprehensive testing and adjustments to the equipment's performance, and replacing aging or severely damaged components based on the equipment's condition and operating years to improve its reliability and lifespan.

[0003] During unit A-level overhaul, large components require support platforms. For example, utility model CN218428193U discloses an intelligent support platform for hydroelectric machinery maintenance. This platform includes a main body with reinforcing triangular supports fixed on both sides for auxiliary support. An adjustable-height lifting mechanism is embedded within the main body. A movable support plate for placing hydroelectric machinery is mounted externally to the lifting mechanism. A steering mechanism for adjusting the angle is fixedly installed at the bottom of the main body. During hydroelectric machinery maintenance, the machinery is placed on the support plate, and the height of the support plate can be adjusted using the lifting mechanism, while the angle of the support plate can be adjusted using the steering mechanism.

[0004] During unit A-level overhaul, there are high requirements for the levelness of support for large components. However, the aforementioned intelligent support platform for hydroelectric machinery maintenance only has simple height and angle adjustment functions. Due to the unevenness of the ground or foundation settlement at the maintenance site, and the fact that the shape and structure of large components are often complex with uneven weight distribution, the aforementioned intelligent support platform for hydroelectric machinery maintenance may deform or sink to varying degrees when supporting large components due to uneven load distribution. At the same time, the support plate itself may have some unevenness or deformation, making it difficult for the aforementioned intelligent support platform for hydroelectric machinery maintenance to meet the required levelness of support for large components. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a horizontal adjustment support system for large components of unit A overhaul, including a hydraulic support device, an electronic level, a hydraulic pump station, and control equipment; the hydraulic support device includes a support block, a hydraulic jack, a pressure plate, a pressure sensor, and a displacement sensor; the body of the hydraulic jack is fixed on the support block; the body of the pressure sensor is mounted on the piston column of the hydraulic jack through an angle adjustment mechanism; the pressure plate is connected to the measuring end of the pressure sensor; and the displacement sensor is used to monitor the displacement value of the piston column of the hydraulic jack. An electronic level, which is mounted on a large maintenance component; Hydraulic pump station, which is connected to the hydraulic jack; The control device is electrically connected to the hydraulic pump station, pressure sensor, displacement sensor and electronic level.

[0006] The angle adjustment mechanism includes a support plate. The piston rod end of the hydraulic jack is provided with an arc-shaped groove. The bottom of the support plate is provided with an arc-shaped boss corresponding to the arc-shaped groove. The arc-shaped boss is placed in the arc-shaped groove. The piston rod of the hydraulic jack is provided with a limiting member for limiting the separation of the support plate from the piston rod of the hydraulic jack. The body of the pressure sensor is fixed on the support plate.

[0007] The hydraulic support device also includes a movable wheel, which is mounted on the support and can be raised and lowered relative to the support. When the movable wheel moves down to contact the ground, it can support the support to lift off the ground.

[0008] The hydraulic support device also includes support plates, and there are two support plates. The two support plates are hinged to both sides of the support pier and can be unfolded and folded relative to the support pier. When the two support plates are unfolded, the bottom surface of the support plate is flush with the bottom surface of the support pier.

[0009] The hydraulic support device further includes a drive mechanism, which is mounted on the support pier. The drive mechanism can simultaneously drive the moving wheel to rise relative to the support pier, and drive the two support plates to unfold relative to the support pier. It can also drive the moving wheel to descend relative to the support pier, and drive the two support plates to fold relative to the support pier.

[0010] The drive mechanism includes a lifting assembly, a retracting assembly, and a power input assembly mounted on the support. The lifting assembly is connected to the moving wheels. The retracting assembly has two sets, each connected to one of the two support plates. The power input assembly is connected to the lifting assembly and the retracting assembly.

[0011] The lifting assembly includes a bracket and a first threaded sleeve. The bracket is provided with a vertical guide rod that slides through the support. The movable wheels are located at both ends of the bracket. The first threaded sleeve is rotatably mounted on the support. The bracket is provided with a first screw that is screwed to the first threaded sleeve. The power input assembly is connected to the first threaded sleeve and is used to drive the first threaded sleeve to rotate.

[0012] The support frame is generally H-shaped, and the support pier is provided with a clearance groove for avoiding the support frame.

[0013] The retraction assembly includes a second screw, a second threaded sleeve, and a connecting rod. The second screw is rotatably mounted on the support, the second threaded sleeve is screwed to the second screw, and the two ends of the connecting rod are respectively hinged to the second threaded sleeve and the support plate. The power input assembly is connected to the second screw and is used to drive the second screw to rotate.

[0014] The power input assembly includes an input shaft, an intermediate shaft, and a transfer shaft rotatably mounted on the support. The input shaft is connected to the intermediate shaft via a first bevel gear pair. A gear ring is provided around the periphery of the first threaded sleeve. A gear meshing with the gear ring is provided on the intermediate shaft. The intermediate shaft is connected to the transfer shaft via a second bevel gear pair. Both ends of the transfer shaft are respectively connected to the second screws of the two sets of the retraction and extension assemblies via a third bevel gear pair.

[0015] The main beneficial effects of this utility model are as follows: When horizontal support is required for large maintenance components, the control equipment simultaneously extends the pistons of multiple hydraulic jacks in the hydraulic support devices, causing the pressure plates of these devices to rise synchronously and contact the bottom surface of the large maintenance component. Pressure sensors in the hydraulic support devices measure the load borne by the pressure plates. The control equipment adjusts the height of each pressure plate, ensuring that each plate is under load and the load deviation is within a threshold range. Based on the measurement signals fed back to the control equipment from the electronic level, the large maintenance component is adjusted to a horizontal position. If the changes in the electronic level and displacement sensor values ​​do not exceed the threshold within one hour, the equipment can proceed for maintenance. This significantly improves the horizontal support accuracy of large maintenance components during unit A-level overhauls. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Figure 1 This is a schematic diagram of the horizontal adjustment support system for the large component of Unit A during maintenance in Embodiment 1 of this utility model; Figure 2 This is a schematic diagram of the hydraulic support device in Embodiment 1 of this utility model; Figure 3 This is a cross-sectional view of the hydraulic support device in Embodiment 1 of this utility model; Figure 4 for Figure 3 A magnified view of part A in the middle; Figure 5 This is a schematic diagram of the hydraulic support device in Embodiment 2 of this utility model; Figure 6 This is a cross-sectional view of the hydraulic support device in Embodiment 2 of this utility model from a first perspective; Figure 7 for Figure 6 A magnified view of part B in the middle section; Figure 8 This is a cross-sectional view of the hydraulic support device in Embodiment 2 of this utility model from a second perspective; Figure 9 for Figure 8 A magnified view of part C in the diagram.

[0018] In the diagram: Support 10; Clearance groove 11; Hydraulic jack 20; Piston column 21; Arc groove 211; Locking nut 22; Support plate 30; Arc boss 31; Clearance groove 311; Groove 312; Support plate 40; First pivot 41; Drive mechanism 50; Bracket 51; Vertical guide rod 511; First screw 512; First threaded sleeve 52; Gear ring 521; Second screw 53; Second threaded sleeve 54; Connecting rod 55; Second pivot 551; Third pivot 55 2; Input shaft 56; First bevel gear pair 561; Second handle 562; Intermediate shaft 57; Gear 571; Second bevel gear pair 572; Transfer shaft 58; Third bevel gear pair 581; Pressure plate 60; Pressure sensor 70; Pull wire sensor 80; Pull rope 81; Control device 90; Moving wheel 100; Wheel frame 101; Scissor jack 110; First handle 111; Limit bolt 120; Limit plate 121; Large maintenance component 130. Detailed Implementation

[0019] The following combination Figures 1-9 This application will be described in further detail below.

[0020] Example 1 Furthermore, this embodiment discloses a horizontal adjustment support system for large components during unit A-level maintenance. like Figures 1 to 4 A horizontal adjustment support system for large components of a generator unit (A-level maintenance) includes a hydraulic support device, an electronic level, a hydraulic pump station, and control equipment 90.

[0021] Multiple hydraulic support devices are provided; in this embodiment, 20 hydraulic support devices are provided. Each hydraulic support device includes a support 10, a hydraulic jack 20, a pressure plate 60, a pressure sensor 70, a displacement sensor, a moving wheel 100, and a lifting drive component.

[0022] The body of the hydraulic jack 20 is fixed on the support 10. The body of the pressure sensor 70 is mounted on the piston column 21 of the hydraulic jack 20 through an angle adjustment mechanism. The pressure plate 60 is connected to the measuring end of the pressure sensor 70. The angle of the pressure plate 60 can be adjusted through the angle adjustment mechanism to ensure that the pressure plate 60 is in close contact with the pressure surface of the large maintenance component 130.

[0023] In an optional embodiment, the specific structure of the angle adjustment mechanism, and its specific connection relationship with the pressure sensor 70 and the piston rod 21, are as follows: The angle adjustment mechanism includes a support plate 30, the piston column 21 of the hydraulic jack 20 is provided with an arc groove 211 at the end, the bottom of the support plate 30 is provided with an arc boss 31 with a shape corresponding to the arc groove 211, the arc boss 31 is placed in the arc groove 211, and the body of the pressure sensor 70 is fixed on the support plate 30.

[0024] The piston rod 21 of the hydraulic jack 20 is provided with a limiting member to prevent the separation of the support plate 30 from the piston rod 21 of the hydraulic jack 20. The limiting member can be a limiting bolt 120. More specifically, the limiting bolt 120 is screwed to the piston rod 21 of the hydraulic jack 20. The arc-shaped boss 31 is provided with a relief groove 311 to avoid the limiting bolt 120 when the arc-shaped boss 31 slides relative to the arc-shaped groove 211. The support plate 30 is provided with a groove 312 that communicates with the relief groove 311. The limiting bolt 120 is provided with a limiting plate 121, which is located in the groove 312 and spaced apart from the bottom surface of the groove 312. The limiting plate 121 is used to prevent the separation of the support plate 30 from the piston rod 21 of the hydraulic jack 20.

[0025] The hydraulic jack 20 can be a double-acting jack and equipped with a hydraulic lock and a mechanical self-locking mechanism to ensure the safety of the device. The hydraulic lock and mechanical self-locking mechanism of the hydraulic jack 20 are existing technologies in the field. The mechanical self-locking mechanism can adopt a common structure in the field, such as a threaded piston rod 21 and a locking nut 22 that cooperates with it.

[0026] The displacement sensor can be a pull-wire sensor 80. The body of the pull-wire sensor 80 is fixed on the support 10, and the pull rope 81 of the pull-wire sensor 80 is fixed to the pressure plate 60. The displacement sensor is used to monitor the displacement value of the piston column 21 of the hydraulic jack 20.

[0027] The movable wheels 100 are located at both ends of the support 10 and can be raised and lowered relative to the support 10. When the movable wheels 100 move down to contact the ground, they can support the support 10 to lift off the ground, so as to facilitate the movement of the hydraulic support device.

[0028] The lifting drive is used to drive the moving wheel 100 to rise and fall relative to the support 10. The lifting drive can be a scissor jack 110. The upper end of the scissor jack 110 is fixed to the support 10, and the lower end of the scissor jack 110 is provided with a wheel frame 101. The moving wheel 100 is mounted on the wheel frame 101. By rotating the first handle 111 of the scissor jack 110, the scissor jack 110 can be extended, thereby driving the moving wheel 100 to move down to contact the ground.

[0029] An electronic level can be mounted on a large maintenance component 130 and used to measure the levelness of the large maintenance component 130. The hydraulic pump station is connected to the hydraulic jack 20 through hydraulic system components such as electromagnetic proportional valves, boosters, hydraulic sensors, solenoid valves, and oil pipes. The control device 90 is electrically connected to the hydraulic pump station, pressure sensor 70, displacement sensor, and electronic level. The control device 90 can be a PLC control device.

[0030] The implementation principle of the horizontal adjustment support system for a large component under maintenance in this embodiment is as follows: When horizontal support is required for the large maintenance component 130, multiple hydraulic support devices are placed on the designated ground of the plant according to the vertices of a regular polygon. Then, the large maintenance component 130 is hoisted above the support pier 10. At this point, the bottom surface of the large maintenance component 130 is 1.3-1.5 meters above the ground, and the upper surface of the pressure plate 60 of the hydraulic support device is approximately 50 millimeters below the bottom surface of the large maintenance component 130. Next, the position of the support pier 10 or the position of the large maintenance component 130 is slightly adjusted until the support pier 10 is exactly below the support point of the large maintenance component 130.

[0031] Next, the pistons 21 of the hydraulic jacks 20 of multiple hydraulic support devices are extended simultaneously by the control device 90, so that the bearing plates 60 of the multiple hydraulic support devices are raised synchronously and come into contact with the bottom surface of the large maintenance component 130. The load borne by the bearing plate 60 is measured by the pressure sensor 70 of the hydraulic support device and the measurement signal is fed back to the control device 90. When the bearing plate 60 of each hydraulic support device bears the same load, the bearing plate 60 is controlled to stop rising, ensuring that the bearing plate 60 of each hydraulic support device is in full contact with the large maintenance component 130.

[0032] Next, an electronic level is placed on the large maintenance component 130. The height of the pressure plate 60 of each hydraulic support device is adjusted via the control device 90. Ensuring that the pressure plate 60 of each hydraulic support device is under load and the load deviation is within a threshold range, the large maintenance component 130 is adjusted to a horizontal state based on the measurement signal fed back to the control device 90 from the electronic level. Once the large maintenance component 130 is horizontal, it is maintained in a horizontal state, and the large maintenance component 130 is synchronously lifted to the required height using multiple hydraulic support devices. Then, the locking nut 22 on the hydraulic jack 20 is tightened to achieve mechanical locking. The values ​​of the pressure sensor 70 and the pull wire sensor 80 are recorded. The hook on the large maintenance component 130 is removed, and the oil pipe between the hydraulic jack 20 and the hydraulic pump station is disconnected. The hydraulic jack 20 is then hydraulically locked using a hydraulic lock. The control device 90 records the measurement values ​​of the electronic level and the pull wire sensor 80. If the value change does not exceed the threshold within one hour, the equipment can proceed for maintenance.

[0033] Example 2 Furthermore, such as Figure 5 and Figure 6 A horizontal adjustment support system for large components of unit A is described. The difference between this embodiment and embodiment 1 is that the hydraulic support device further includes a support plate 40 and a drive mechanism 50. There are two support plates 40, which are hinged to the two sides of the support pier 10 via a first pivot 41. They can be unfolded or folded relative to the support pier 10. When the two support plates 40 are unfolded, the bottom surface of the support plate 40 is flush with the bottom surface of the support pier 10, thereby increasing the contact area between the hydraulic support device and the ground and improving the stability of the support.

[0034] The drive mechanism 50 is mounted on the support 10. The drive mechanism 50 can simultaneously drive the moving wheel 100 to rise relative to the support 10 and drive the two support plates 40 to unfold relative to the support 10. When the two support plates 40 unfold to the point that their bottom surfaces are flush with the bottom surfaces of the support 10, the moving wheel 100 rises relative to the support 10 and is lifted off the ground, thereby supporting the hydraulic support device through the support plates 40 and the support 10.

[0035] The drive mechanism 50 can also simultaneously drive the moving wheel 100 to descend relative to the support 10 and drive the two support plates 40 to fold relative to the support 10. When the two support plates 40 are fully folded, the moving wheel 100 descends relative to the support 10 to support the ground and lifts the support 10 off the ground. Thus, the hydraulic support device can be moved by the moving wheel 100. Since the two support plates 40 are folded at this time, the support plates 40 can avoid occupying too much space when moving.

[0036] Furthermore, such as Figures 7 to 9In an optional embodiment, the specific structure of the drive mechanism 50 and its specific connection relationship with the moving wheel 100 and the support plate 40 are as follows: The drive mechanism 50 includes a lifting assembly, a retracting assembly and a power input assembly provided on the support 10. The lifting assembly is connected to the moving wheel 100. The retracting assembly is provided in two sets and is respectively connected to the two support plates 40. The power input assembly is connected to the lifting assembly and the retracting assembly.

[0037] Furthermore, the lifting assembly can adopt the following structure: the lifting assembly includes a bracket 51 and a first threaded sleeve 52. The bracket 51 is provided with a vertical guide rod 511 that slides through the support 10. The moving wheel 100 is provided on the bracket 51. The first threaded sleeve 52 is rotatably provided on the support 10. The bracket 51 is provided with a first screw 512 that is screwed to the first threaded sleeve 52. The power input assembly is connected to the first threaded sleeve 52 and is used to drive the first threaded sleeve 52 to rotate. The bracket 51 is generally I-shaped. The support 10 is provided with a clearance groove 11 for avoiding the bracket 51.

[0038] Furthermore, the retraction assembly can adopt the following structure: the retraction assembly includes a second screw 53, a second screw sleeve 54, and a connecting rod 55. The second screw 53 is rotatably mounted on the support 10. The second screw sleeve 54 is screwed to the second screw 53. The two ends of the connecting rod 55 are respectively hinged to the second screw sleeve 54 and the support plate 40 through a second pivot 551 and a third pivot 552. The power input assembly is connected to the second screw 53 and is used to drive the second screw 53 to rotate.

[0039] Furthermore, the power input assembly can adopt the following structure: The power input assembly includes an input shaft 56, an intermediate shaft 57, and a transfer shaft 58 rotatably mounted on the support 10. The input shaft 56 is connected to the intermediate shaft 57 via a first bevel gear pair 561. The input shaft 56 is provided with a second handle 562. The periphery of the first threaded sleeve 52 is provided with a gear ring 521. The intermediate shaft 57 is provided with a gear 571 that meshes with the gear ring 521. The intermediate shaft 57 is connected to the transfer shaft 58 via a second bevel gear pair 572. The two ends of the transfer shaft 58 are respectively connected to the second screws 53 of the two sets of retraction and extension assemblies via a third bevel gear pair 581.

[0040] The implementation principle of the horizontal adjustment support system for a large component of unit A maintenance in this embodiment is as follows: When it is necessary to drive the moving wheel 100 to rise and fall through the drive mechanism 50, and to drive the support plate 40 to extend and retract, the input shaft 56 is rotated through the second handle 562, which drives the intermediate shaft 57 to rotate, and drives the first screw sleeve 52 to rotate through the gear 571 and the gear ring 521. Under the interaction between the first screw sleeve 52 and the first screw 512, the first screw 512, the bracket 51 and the moving wheel 100 are driven to rise and fall.

[0041] When the input shaft 56 rotates, it drives the distribution shaft 58 to rotate through the intermediate shaft 57. Then, the distribution shaft 58 drives the second screw 53 to rotate. Under the interaction between the second screw 53 and the second screw sleeve 54, the second screw sleeve 54 is driven to rise and fall. Then, the connecting rod 55 drives the support plate 40 to rotate around the axis of the first pivot 41, so as to unfold or fold.

[0042] The above embodiments are merely preferred technical solutions of this utility model and should not be considered as limitations on this utility model. The embodiments and features described in this application can be arbitrarily combined without conflict. The protection scope of this utility model should be defined as the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the protection scope of this utility model.

Claims

1. A horizontal adjustment support system for large components during unit A-level maintenance, characterized in that: The system includes a hydraulic support device, an electronic level, a hydraulic pump station, and a control device (90). The hydraulic support device includes a support (10), a hydraulic jack (20), a pressure plate (60), a pressure sensor (70), and a displacement sensor. The hydraulic jack (20) is mounted on the support (10). The pressure sensor (70) is mounted on the piston column (21) of the hydraulic jack (20) via an angle adjustment mechanism. The pressure plate (60) is connected to the measuring end of the pressure sensor (70). The displacement sensor is used to monitor the displacement value of the piston column (21) of the hydraulic jack (20). An electronic level, which is mounted on a large maintenance component (130); A hydraulic pump station, which is connected to the hydraulic jack (20); The control device (90) is electrically connected to the hydraulic pump station, pressure sensor (70), displacement sensor and electronic level.

2. The horizontal adjustment support system for large components during unit A-level maintenance according to claim 1, characterized in that: The angle adjustment mechanism includes a support plate (30), the piston column (21) of the hydraulic jack (20) is provided with an arc groove (211) at the end, the bottom of the support plate (30) is provided with an arc boss (31) with a shape corresponding to the arc groove (211), the arc boss (31) is placed in the arc groove (211), the piston column (21) of the hydraulic jack (20) is provided with a limiting member for limiting the separation of the support plate (30) and the piston column (21) of the hydraulic jack (20), and the pressure sensor (70) is provided on the support plate (30).

3. The horizontal adjustment support system for large components during unit A-level maintenance according to claim 1, characterized in that: The hydraulic support device also includes a movable wheel (100), which is mounted on the support (10) and can be raised and lowered relative to the support (10). When the movable wheel (100) moves down to contact the ground, it can support the support (10) to lift off the ground.

4. The horizontal adjustment support system for large components during unit A-level maintenance according to claim 3, characterized in that: The hydraulic support device also includes a support plate (40), which has two plates. The two support plates (40) are hinged to the two sides of the support pier (10) and can be unfolded and folded relative to the support pier (10). When the two support plates (40) are unfolded, the bottom surface of the support plate (40) is flush with the bottom surface of the support pier (10).

5. The horizontal adjustment support system for large components during unit A-level maintenance according to claim 4, characterized in that: The hydraulic support device further includes a drive mechanism (50), which is mounted on the support (10). The drive mechanism (50) can simultaneously drive the moving wheel (100) to rise relative to the support (10), and drive the two support plates (40) to unfold relative to the support (10). It can also drive the moving wheel (100) to fall relative to the support (10), and drive the two support plates (40) to fold relative to the support (10).

6. The horizontal adjustment support system for large components during unit A-level maintenance according to claim 5, characterized in that: The drive mechanism (50) includes a lifting assembly, a retracting assembly and a power input assembly mounted on the support (10). The lifting assembly is connected to the moving wheel (100). The retracting assembly is provided in two sets and is connected to the two support plates (40) respectively. The power input assembly is connected to the lifting assembly and the retracting assembly.

7. A horizontal adjustment support system for large components during unit A-level maintenance according to claim 6, characterized in that: The lifting assembly includes a bracket (51) and a first threaded sleeve (52). The bracket (51) is provided with a vertical guide rod (511) that slides through the support (10). The moving wheels (100) are provided at both ends of the bracket (51). The first threaded sleeve (52) is rotatably mounted on the support (10). The bracket (51) is provided with a first screw (512) that is screwed to the first threaded sleeve (52). The power input assembly is connected to the first threaded sleeve (52) and is used to drive the first threaded sleeve (52) to rotate.

8. A horizontal adjustment support system for large components during unit A-level maintenance according to claim 7, characterized in that: The support (51) is in the shape of an I-beam, and the support (10) is provided with a clearance groove (11) for avoiding the support (51).

9. A horizontal adjustment support system for large components during unit A-level maintenance according to claim 7, characterized in that: The retraction assembly includes a second screw (53), a second screw sleeve (54), and a connecting rod (55). The second screw (53) is rotatably mounted on the support (10). The second screw sleeve (54) is screwed to the second screw (53). The two ends of the connecting rod (55) are respectively hinged to the second screw sleeve (54) and the support plate (40). The power input assembly is connected to the second screw (53) and is used to drive the second screw (53) to rotate.

10. A horizontal adjustment support system for large components during unit A-level maintenance according to claim 9, characterized in that: The power input assembly includes an input shaft (56), an intermediate shaft (57), and a transfer shaft (58) rotatably mounted on the support (10). The input shaft (56) is connected to the intermediate shaft (57) via a first bevel gear pair (561). A gear ring (521) is provided around the periphery of the first threaded sleeve (52). A gear (571) meshing with the gear ring (521) is provided on the intermediate shaft (57). The intermediate shaft (57) is connected to the transfer shaft (58) via a second bevel gear pair (572). The two ends of the transfer shaft (58) are respectively connected to the second screws (53) of the two sets of the retraction assembly via a third bevel gear pair (581).

Images