A method for machining sealing groove on lower end face of movable guide vane of hydropower station

Abstract

A method for processing a sealing groove on the lower end face of a movable guide vane of a hydropower station adopts a plane milling device, which comprises a base plate, a cantilever frame, an X-axis moving system, a Y-axis moving system, a Z-axis moving system, a movable back plate, a threaded column and a milling cutter; the base plate is placed on a boss inside a movable guide vane wall, a cantilever frame is mounted on the base plate, a movable back plate is arranged on the cantilever frame, a lifting platform is arranged on the movable back plate, and a milling cutter is arranged on the lifting platform; a milling motor is arranged on the upper end face of the lifting platform, a reducer is arranged on the lower end face of the lifting platform, and the reducer is movably connected to the milling cutter through a connecting head; the present invention replaces manual labor with automated equipment, which greatly improves the processing efficiency and quality of the sealing groove on the lower end face of the guide vane while ensuring the safety of work operations.

Description

Technical Field

[0001] The invention relates to the field of hydropower station component maintenance methods, and in particular to a method for machining a sealing groove on a lower end surface of a movable guide vane of a hydropower station. Background Art

[0002] During the long-term operation of large hydropower station units, the seal of the lower end face of the movable guide vane of the power station is subjected to varying degrees of cavitation and abrasion due to the action of water flow. The original dovetail seal groove is basically destroyed and the seal cannot be installed tightly. After the sealing strip is installed, after a short period of operation, almost all the seals are washed away by the water flow and cannot play a sealing role. In serious cases, there may be a risk of unit creep.

[0003] In order to ensure the stable operation of the hydropower station unit, the supporting components need to be polished regularly. The traditional processing method is usually manual grinding. However, due to the special working environment, the above method is difficult to ensure the personal safety of workers during actual operation, and the quality of manual milling is also difficult to achieve the best. Therefore, it is necessary to design and manufacture a set of processing equipment that is easy to install and meets the requirements of on-site use. The equipment also has the functions of milling planes and grooves, as well as drilling. Summary of the invention

[0004] In view of the technical problems existing in the background technology, the present invention provides a method for processing the sealing groove on the lower end face of the movable guide vane of a hydropower station, which replaces manual labor with automated equipment, thereby greatly improving the processing efficiency and quality of the sealing groove on the lower end face of the guide vane while ensuring the safety of work operations.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve:

[0006] A method for processing a sealing groove on the lower end face of a movable guide vane of a hydropower station adopts a plane milling device, which comprises a base plate, a cantilever frame, an X-axis moving system, a Y-axis moving system, a Z-axis moving system, a movable back plate, a threaded column and a milling cutter; the base plate is placed on a boss inside a movable guide vane wall, a cantilever frame is installed on the base plate, a movable back plate is provided on the cantilever frame, a lifting platform is provided on the movable back plate, and a milling cutter is provided on the lifting platform; a milling motor is installed on the upper end face of the lifting platform, a reducer is provided on the lower end face of the lifting platform, and the reducer is movably connected to the milling cutter through a connecting head.

[0007] The method comprises the following steps:

[0008] Step 1. Transport the equipment to the designated location and unpack and inspect;

[0009] Step 2: Assemble the equipment components in order;

[0010] 2.1. Make tooling plates according to the relevant dimensions of the bed base, and use them to hoist, transport and install the equipment as a whole;

[0011] 2.2. Adjust the position of the base plate according to the processing range, then hoist the cantilever frame components onto the base plate slide rails and adjust the height of the threaded column;

[0012] 2.3. Install the milling cutter and lock the cutter head, then install the milling motor and reducer;

[0013] Step 3. Adjust the device status;

[0014] 3.1. Adjust the positions of the X-axis moving system, Y-axis moving system and Z-axis moving system on the machine tool, start the drive motors on the X-axis moving system, Y-axis moving system and Z-axis moving system and make them move at a low speed, and observe the operation of each component;

[0015] 3.2. Place a bar level on the bottom plate and the cantilever frame, read and record the level parameters, and adjust the height of the threaded column to keep the entire machine body level;

[0016] Step 4. Start the equipment and adjust the position of the milling cutter to achieve the best working position;

[0017] 4.1. Adjust the position of the milling cutter in the X-axis direction through the X-axis moving system;

[0018] 4.2. Adjust the position of the milling cutter in the Y-axis direction through the Y-axis moving system;

[0019] 4.3. Adjust the position of the milling cutter in the Y-axis direction through the Z-axis moving system;

[0020] Step 5. Use the connector to replace the milling cutter head, and then process the sealing groove below;

[0021] 5.1. Install the end milling cutter head and mill the sealing groove below;

[0022] 5.2. Replace the drill chuck and twist drill, and drill the thread bottom hole of the sealing groove below;

[0023] 5.3. Replace the drill chuck and dovetail milling cutter, and mill the dovetail groove of the lower sealing groove;

[0024] Step 6. After processing, remove all components, lubricate them, and do anti-corrosion treatment.

[0025] In a preferred embodiment, the X-axis movement system includes a first rotating motor, a first slide rail, a first screw rod, a first transmission assembly and a first top plate; the first rotating motor is installed on the upper end surface of the base plate, the first slide rail is arranged parallel to the base plate, the transmission shaft of the first rotating motor is connected to the first screw rod and drives the first screw rod to rotate freely around its own axis, the other end of the first screw rod is movably connected to the first top plate, the lower end surface of the cantilever frame is clamped with the first slide rail through a slider, the first screw rod is provided with a first transmission assembly, the first transmission assembly is fixedly connected to the lower end surface of the cantilever frame, and the rotation of the first screw rod drives the first transmission assembly and the cantilever frame to slide synchronously along the first slide rail.

[0026] In the preferred scheme, the Z-axis movement system includes a second rotating motor, a second slide rail, a second screw rod, a second transmission assembly and a second top plate; the second rotating motor is installed at the side wall of the cantilever frame, and the second slide rail is arranged parallel to the cantilever frame. The transmission shaft of the second rotating motor is connected to the second screw rod and drives the second screw rod to rotate freely around its own axis. The other end of the second screw rod is movably connected to the second top plate, and the lower end surface of the movable back plate is clamped with the second slide rail through a slider. The second screw rod is provided with a second transmission assembly, and the second transmission assembly is fixedly connected to the lower end surface of the movable back plate. The rotation of the second screw rod drives the second transmission assembly and the movable back plate to slide synchronously along the second slide rail.

[0027] In the preferred scheme, the Y-axis moving system includes a third rotating motor, a third slide rail, a third screw rod and a third transmission assembly; the third rotating motor is installed at the upper end of the movable back plate, the third slide rail is arranged parallel to the movable back plate, the transmission shaft of the third rotating motor is connected to the third screw rod and drives the third screw rod to rotate freely around its own axis, the side wall of the lifting platform is clamped with the third slide rail through a slider, and the third screw rod is provided with a third transmission assembly, and the third transmission assembly is fixedly connected to the side wall of the lifting platform, and the rotation of the third screw rod drives the third transmission assembly and the lifting platform to slide synchronously along the third slide rail.

[0028] In a preferred solution, threaded columns are vertically arranged on both sides of the base plate, the threaded columns are threadedly connected to the base plate, the upper ends of the threaded columns are fixedly connected to the center of the turntable, and the lower ends of the threaded columns are fixedly connected to the center of the supporting chassis.

[0029] In the preferred solution, fixed rods are vertically installed on both sides of the bottom plate, fixed brackets are fixedly installed on the movable guide vane wall, and the fixed rods are movably connected to the fixed brackets;

[0030] The upper end of the fixing rod is a threaded connector, and the end of the fixing bracket is provided with a concave connector, which is clamped in the threaded connector. The threaded connector is sleeved with a lower locking nut and an upper locking nut to clamp and fix the concave connector together.

[0031] This patent can achieve the following beneficial effects:

[0032] 1. This device can automatically adjust the position of the milling cutter through the X, Y, and Z axis moving system, and effectively improve the processing accuracy;

[0033] 2. This device can realize automatic processing through the milling motor and the feed system. Compared with the traditional manual processing method, its safety and processing efficiency have been greatly improved;

[0034] 3. The device can be used in a small working space, and all parts of the device can be freely disassembled and assembled, which is convenient for later maintenance;

[0035] 4. The device adopts modular and portable design, which solves the problems of transportation and installation of equipment in special environments; segmented shift processing realizes the problem of processing large-size workpieces with small machine tools; the XYZ three-axis linkage function solves the problems of groove milling, curve contour milling, etc.; the universal tool system can be installed with end mills, twist drills, dovetail milling cutters and other tools, and multiple process processing can be achieved at the same workstation by replacing different tools. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0037] Figure 1 It is a schematic diagram of the working state of the overall structure of the present invention;

[0038] Figure 2 It is a schematic diagram of the structure of the main components of the present invention;

[0039] Figure 3 It is a schematic diagram of the structure of the X-axis and Z-axis moving system of the present invention;

[0040] Figure 4 It is an enlarged schematic diagram of the Y-axis moving system of the present invention;

[0041] Figure 5 It is an enlarged schematic diagram of the threaded column structure of the present invention;

[0042] Figure 6 It is an enlarged schematic diagram of the connection parts of the fixing rod and the fixing bracket of the present invention.

[0043] In the figure: movable guide vane wall 1, boss 2, bottom plate 3, fixed rod 4, threaded connector 401, X-axis moving system 5, first rotating motor 501, first slide rail 502, first screw rod 503, first transmission assembly 504, first top plate 505, cantilever frame 6, movable back plate 7, fixed bracket 8, concave connector 801, Z-axis moving system 9, second rotating motor 901, second slide rail 902, second screw rod 903, second transmission assembly 904, second top plate 905, Y-axis moving system 10, third rotating motor 101, third slide rail 102, third screw rod 103, third transmission assembly 104, lifting platform 11, milling motor 12, reducer 13, connector 14, milling cutter 15, threaded column 16, turntable 17, support chassis 18, lower locking nut 19, upper locking nut 20. DETAILED DESCRIPTION

[0044] like Figure 1 and Figure 2 As shown, a plane milling device for a turbine support component includes a base plate 3, a cantilever frame 6, an X-axis moving system 5, a Y-axis moving system 10, a Z-axis moving system 9, a movable back plate 7 and a milling cutter 15. The base plate 3 is placed on a boss 2 inside a movable guide vane wall 1, the cantilever frame 6 is mounted on the base plate 3, the movable back plate 7 is disposed on the cantilever frame 6, the movable back plate 7 is disposed on a lifting platform 11, and the lifting platform 11 is disposed on a milling cutter 15;

[0045] An X-axis moving system 5 is provided between the cantilever frame 6 and the base plate 3, and the X-axis moving system 5 controls the cantilever frame 6 to slide limitedly along the base plate 3. A Z-axis moving system 9 is provided between the cantilever frame 6 and the movable back plate 7, and the Z-axis moving system 9 controls the movable back plate 7 to slide limitedly along the cantilever frame 6. A Z-axis moving system 9 is provided between the movable back plate 7 and the lifting platform 11, and the Z-axis moving system 9 controls the lifting platform 11 to slide limitedly along the movable back plate 7. The milling cutter 15 can be adjusted in the X, Y, and Z axis directions through the X, Y, and Z axis moving systems, thereby realizing the work of automatically adjusting the milling cutter 15.

[0046] The preferred solution is Figure 3As shown, the X-axis movement system 5 includes a first rotating motor 501, a first slide rail 502, a first screw rod 503, a first transmission assembly 504 and a first top plate 505; the first rotating motor 501 is installed on the upper end surface of the base plate 3, and the first slide rail 502 is arranged parallel to the base plate 3. The transmission shaft of the first rotating motor 501 is connected to the first screw rod 503 and drives the first screw rod 503 to rotate freely around its own axis. The other end of the first screw rod 503 is movably connected to the first top plate 505, and the lower end surface of the cantilever frame 6 is clamped with the first slide rail 502 through a slider. The first screw rod 503 is provided with a first transmission assembly 504, and the first transmission assembly 504 is fixedly connected to the lower end surface of the cantilever frame 6. When the device is working, the first rotating motor 501 drives the first screw rod 503 to rotate around its own axis. The rotation of the first screw rod 503 drives the first transmission assembly 504 and the cantilever frame 6 to slide synchronously along the first slide rail 502, thereby realizing the process of adjusting the milling cutter 15 in the X-axis direction.

[0047] The preferred solution is Figure 3 As shown, the Z-axis moving system 9 includes a second rotating motor 901, a second slide rail 902, a second screw rod 903, a second transmission assembly 904 and a second top plate 905; the second rotating motor 901 is installed at the side wall of the cantilever frame 6, and the second slide rail 902 is arranged parallel to the cantilever frame 6. The transmission shaft of the second rotating motor 901 is connected to the second screw rod 903 and drives the second screw rod 903 to rotate freely around its own axis. The other end of the second screw rod 903 is movably connected to the second top plate 905, and the lower end surface of the movable back plate 7 is clamped with the second slide rail 902 through a slider. The second screw rod 903 is provided with a second transmission assembly 904, and the second transmission assembly 904 is fixedly connected to the lower end surface of the movable back plate 7. When the device is working, the rotating motor 901 drives the second screw rod 903 to rotate around its own axis. The rotation of the second screw rod 903 drives the second transmission assembly 904 and the movable back plate 7 to slide synchronously along the second slide rail 902, thereby realizing the process of adjusting the milling cutter 15 in the Z-axis direction.

[0048] The preferred solution is Figure 4As shown, the Y-axis movement system 10 includes a third rotating motor 101, a third slide rail 102, a third screw rod 103 and a third transmission assembly 104; the third rotating motor 101 is installed at the upper end of the movable back plate 7, and the third slide rail 102 is arranged parallel to the movable back plate 7. The transmission shaft of the third rotating motor 101 is connected to the third screw rod 103 and drives the third screw rod 103 to rotate freely around its own axis. The side wall of the lifting platform 11 is clamped with the third slide rail 102 through a slider, and the third screw rod 103 is provided with a third transmission assembly 104, and the third transmission assembly 104 is fixedly connected to the side wall of the lifting platform 11. When the device is working, the third rotating motor 101 drives the third screw rod 103 to rotate around its own axis, and the rotation of the third screw rod 103 drives the third transmission assembly 104 and the lifting platform 11 to slide synchronously along the third slide rail 102, thereby realizing the process of adjusting the milling cutter 15 in the Y-axis direction.

[0049] The preferred solution is Figure 5 As shown, threaded columns 16 are vertically arranged on both sides of the base plate 3, and the threaded columns 16 are threadedly connected to the base plate 3. The upper ends of the threaded columns 16 are fixedly connected to the center of the turntable 17, and the lower ends of the threaded columns 16 are fixedly connected to the center of the supporting chassis 18. When the device is working, the extension distance of the threaded columns 16 can be adjusted by rotating the turntable 17, so that the base plate 3 can be supported on bosses 2 at different heights.

[0050] The preferred solution is Figure 6 As shown, fixing rods 4 are vertically installed on both sides of the base plate 3, and fixing brackets 8 are fixedly installed on the movable guide vane wall 1, and the fixing rods 4 and the fixed fixing brackets 8 are movably connected; the upper end of the fixing rod 4 is a threaded connector 401, and the end of the fixing bracket 8 is provided with a concave connector 801, which is clamped in the threaded connector 401, and the threaded connector 401 is sleeved with a lower locking nut 19 and an upper locking nut 20. When it is necessary to connect the fixing rod 4, it is only necessary to tighten the upper locking nut 20 upwards and then tighten the lower locking nut 19 downwards. The lower locking nut 19 and the upper locking nut 20 can jointly clamp and fix the concave connector 801 to ensure the stability of the entire device during the milling process.

[0051] The preferred solution is Figure 4 As shown, a milling motor 12 is installed on the upper end surface of the lifting platform 11, and a reducer 13 is installed on the lower end surface of the lifting platform 11. The reducer 13 is movably connected to the milling cutter 15 through a connecting head 14. During the actual use of the device, a suitable milling cutter 15 is selected according to the actual situation. The reamer and milling cutter 15 can also be quickly replaced through the connecting head 14, and it is convenient for the maintenance and repair of the equipment at a later time.

[0052] Example:

[0053] Step 1. Transport the equipment to the designated location and unpack and inspect;

[0054] Step 2: Assemble the equipment components in order;

[0055] 2.1. Make tooling plates according to the relevant dimensions of the bed base, and use them to hoist, transport and install the equipment as a whole;

[0056] 2.2. Adjust the position of the base plate 3 according to the processing range, then hoist the cantilever frame 6 components onto the slide rail of the base plate 3, and adjust the height of the threaded column 16;

[0057] 2.3. Install the milling cutter 15 and lock the cutter head, then install the milling motor 12 and the reducer 13;

[0058] Step 3. Adjust the device status;

[0059] 3.1. Adjust the positions of the X-axis moving system 5, the Y-axis moving system 10 and the Z-axis moving system 9 on the machine tool, start the drive motors on the X-axis moving system 5, the Y-axis moving system 10 and the Z-axis moving system 9 and move them at a low speed, and observe the operation of each component;

[0060] 3.2. Place a bar level on the bottom plate 3 and the cantilever frame 6, read and record the level parameters, and adjust the height of the threaded column 16 to keep the entire machine body level;

[0061] Step 4, start the equipment and adjust the position of the milling cutter 15 to achieve the best working position;

[0062] 4.1. Adjust the position of the milling cutter 15 in the X-axis direction through the X-axis moving system 5;

[0063] 4.2. Adjust the position of the milling cutter 15 in the Y-axis direction through the Y-axis moving system 10;

[0064] 4.3. Adjust the position of the milling cutter 15 in the Y-axis direction through the Z-axis moving system 9;

[0065] Step 5, use the connector 14 to replace the cutter head of the milling cutter 15, and then process the sealing groove below;

[0066] 5.1. Install the end milling cutter head and mill the sealing groove below;

[0067] 5.2. Replace the drill chuck and twist drill, and drill the thread bottom hole of the sealing groove below;

[0068] 5.3. Replace the drill chuck and dovetail milling cutter, and mill the dovetail groove of the lower sealing groove;

[0069] Step 6. After processing, dismantle each component, lubricate each component, and do anti-corrosion treatment;

[0070] In Step 5, the recommended cutting parameters for each process are as follows:

[0071]

[0072] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The various technical features described in the present invention can be combined with each other without conflict. The protection scope of the present invention shall be the technical solutions described in the claims, including the equivalent replacement solutions of the technical features in the technical solutions described in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for processing the sealing groove on the lower end face of the movable guide vane of a hydropower station, characterized in that: The method adopts a plane milling device, which comprises a base plate (3), a cantilever frame (6), an X-axis moving system (5), a Y-axis moving system (10), a Z-axis moving system (9), a movable back plate (7), a threaded column (16) and a milling cutter (15); the base plate (3) is placed on a boss (2) inside a movable guide vane wall (1), the base plate (3) is provided with a cantilever frame (6), the movable back plate (7) is provided with a lifting platform (11), and the lifting platform (11) is provided with a milling cutter (15); a milling motor (12) is provided on the upper end surface of the lifting platform (11), and a reducer (13) is provided on the lower end surface of the lifting platform (11), and the reducer (13) is movably connected to the milling cutter (15) via a connector (14); Threaded columns (16) are vertically arranged on both sides of the bottom plate (3), the threaded columns (16) are threadedly connected to the bottom plate (3), the upper ends of the threaded columns (16) are fixedly connected to the center of the turntable (17), and the lower ends of the threaded columns (16) are fixedly connected to the center of the supporting bottom plate (18); Fixed rods (4) are vertically mounted on both sides of the bottom plate (3); a fixed bracket (8) is fixedly mounted on the movable guide vane wall (1); the fixed rod (4) and the fixed bracket (8) are movably connected; the upper end of the fixed rod (4) is a threaded connector (401); the end of the fixed bracket (8) is provided with a concave connector (801); the concave connector (801) is clamped in the threaded connector (401); a lower locking nut (19) and an upper locking nut (20) are sleeved on the threaded connector (401) and together clamp the concave connector (801); The method comprises the following steps: Step 1. Transport the equipment to the designated location and unpack and inspect; Step 2: Assemble the equipment components in order; 2.

1. Make tooling plates according to the relevant dimensions of the bed base, and use them to hoist, transport and install the equipment as a whole; 2.

2. Adjust the position of the base plate (3) according to the processing range, then hoist the cantilever frame (6) components onto the slide rails of the base plate (3), and adjust the height of the threaded column (16); 2.

3. Install the milling cutter (15) and lock the cutter head, then install the milling motor (12) and the reducer (13); Step 3. Adjust the device status; 3.

1. Adjust the positions of the X-axis moving system (5), the Y-axis moving system (10) and the Z-axis moving system (9) on the machine tool, start the drive motors on the X-axis moving system (5), the Y-axis moving system (10) and the Z-axis moving system (9) and move them at a low speed, and observe the operation of the various components; 3.

2. Place a bar level on the bottom plate (3) and the cantilever frame (6), read and record the level parameters, and adjust the height of the threaded column (16) to keep the entire machine body level; Step 4, start the equipment and adjust the position of the milling cutter (15) to achieve the best working position; 4.

1. Adjusting the position of the milling cutter (15) in the X-axis direction by the X-axis moving system (5); 4.

2. Adjusting the position of the milling cutter (15) in the Y-axis direction by the Y-axis moving system (10); 4.

3. Adjusting the position of the milling cutter (15) in the Z-axis direction by means of the Z-axis moving system (9); Step 5, use the connector (14) to replace the cutter head of the milling cutter (15), and then process the sealing groove below; 5.

1. Install the end milling cutter head and mill the sealing groove below; 5.

2. Replace the drill chuck and twist drill, and drill the thread bottom hole of the sealing groove below; 5.

3. Replace the drill chuck and dovetail milling cutter, and mill the dovetail groove of the lower sealing groove; Step 6. After processing, remove all components, lubricate them, and do anti-corrosion treatment.

2. The method for processing the sealing groove on the lower end surface of the movable guide vane of a hydropower station according to claim 1, characterized in that: The X-axis moving system (5) comprises a first rotating motor (501), a first slide rail (502), a first screw rod (503), a first transmission assembly (504) and a first top plate (505); the first rotating motor (501) is mounted on the upper end surface of the bottom plate (3), the first slide rail (502) is arranged parallel to the bottom plate (3), the transmission shaft of the first rotating motor (501) is connected to the first screw rod (503) and drives the first screw rod (503) to freely rotate around its own axis. The first screw rod (503) is rotated, the other end of the first screw rod (503) is movably connected to the first top plate (505), the lower end surface of the cantilever frame (6) is clamped with the first slide rail (502) through a slider, and a first transmission assembly (504) is provided on the first screw rod (503), and the first transmission assembly (504) is fixedly connected to the lower end surface of the cantilever frame (6). The rotation of the first screw rod (503) drives the first transmission assembly (504) and the cantilever frame (6) to slide synchronously along the first slide rail (502).

3. The method for processing the sealing groove on the lower end surface of the movable guide vane of a hydropower station according to claim 1, characterized in that: The Z-axis moving system (9) comprises a second rotating motor (901), a second slide rail (902), a second screw rod (903), a second transmission assembly (904) and a second top plate (905); the second rotating motor (901) is mounted on the side wall of the cantilever frame (6), the second slide rail (902) is arranged parallel to the cantilever frame (6), and the transmission shaft of the second rotating motor (901) is connected to the second screw rod (903) and drives the second screw rod (903) to rotate freely around its own axis. The second screw rod (903) is rotated, the other end of the second screw rod (903) is movably connected to the second top plate (905), the lower end surface of the movable back plate (7) is clamped with the second slide rail (902) through a slider, and a second transmission assembly (904) is provided on the second screw rod (903), and the second transmission assembly (904) is fixedly connected to the lower end surface of the movable back plate (7). The second screw rod (903) rotates to drive the second transmission assembly (904) and the movable back plate (7) to slide synchronously along the second slide rail (902).

4. The method for processing the sealing groove on the lower end surface of the movable guide vane of a hydropower station according to claim 1, characterized in that: The Y-axis moving system (10) comprises a third rotating motor (101), a third slide rail (102), a third screw rod (103) and a third transmission assembly (104); the third rotating motor (101) is arranged at the upper end of the movable back plate (7); the third slide rail (102) is arranged parallel to the movable back plate (7); the transmission shaft of the third rotating motor (101) is connected to the third screw rod (103) and drives the third screw rod (103) to rotate freely around its own axis; the side wall of the lifting platform (11) is clamped with the third slide rail (102) through a slider; the third screw rod (103) is provided with a third transmission assembly (104); the third transmission assembly (104) is fixedly connected to the side wall of the lifting platform (11); the third screw rod (103) rotates to drive the third transmission assembly (104) and the lifting platform (11) to slide synchronously along the third slide rail (102).

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