Welding equipment for automatic welding
By designing adjustable support components and distance adjustment components, the problem of traditional welding equipment being unable to adjust flexibly has been solved, achieving stable support and clamping of parts of different specifications, and improving welding quality and efficiency.
Patent Information
- Application Number
- CN202520210747.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-11
- Publication Date
- 2025-12-09
- Estimated Expiration
- 2035-02-11
AI Technical Summary
Traditional welding equipment lacks effective support for the weld joint and cannot be flexibly adjusted according to the different diameter specifications of the parts to be welded, resulting in unstable welding and potentially causing part displacement and uneven welding.
An adjustable support assembly and a distance adjustment assembly were designed. The height and position of the support rollers can be adjusted by adjusting the bidirectional threaded rod and the moving lead screw. Together with the movement and rotation of the three-jaw chuck, stable support and clamping at the welding point are ensured.
It achieves stable support and clamping of welded parts with different diameters and lengths, preventing parts from shifting during welding and improving welding quality and production efficiency.
Smart Images

Figure CN223643060U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of welding equipment technology, and in particular to an automatic welding equipment. Background Technology
[0002] With the rapid development of industrialization and automation, shaft and tube parts are increasingly used in the manufacturing field and are widely applied in various equipment and engineering projects. In order to ensure that these parts have sufficient strength and durability during use, effective welding treatment is often required.
[0003] Traditional welding equipment often lacks effective support for the weld joint or uses a fixed support method. During the welding process, it cannot be flexibly adjusted according to the different diameter specifications of the parts to be welded, making it difficult to effectively support the weld joint of the two parts to be welded. This can easily lead to unstable support at the weld joint, which may cause parts to shift, uneven welding, or even affect the welding quality. Therefore, those skilled in the art have provided an automatic welding equipment to solve the problems mentioned in the background art. Utility Model Content
[0004] The purpose of this utility model is to address the shortcomings of existing technologies by proposing an automatic welding equipment. By incorporating an adjustable support component, the support portion at the welding point can be adjusted according to the diameter of the workpieces to be welded. This allows the corresponding support rollers to effectively adhere to the surfaces of the two workpieces, providing effective support at the welding point. This achieves multi-specification adaptability of the support portion at the welding point, effectively improving production efficiency and welding quality.
[0005] To achieve the above objectives, the present invention provides the following technical solution: an automatic welding equipment, comprising a base, a welding gun and two movable frames, wherein an adjustable support assembly is provided between the welding gun and the base, a distance adjustment assembly is provided between the two movable frames and the base, and a three-jaw chuck is rotatably connected to the upper part of the inner wall of one side of each of the two movable frames.
[0006] The adjustable support assembly includes two support frames and a connecting shaft. The two support frames are fixedly connected to the base. An adjusting frame is fixedly connected to the upper end of the two support frames. A bidirectional threaded rod is rotatably connected between the front and rear inner walls of the adjusting frame. An adjusting slider is threadedly sleeved on the front and rear parts of the outer wall of the bidirectional threaded rod. An adjusting rod is hinged to both sides of the upper end of the two adjusting sliders. The connecting shaft is rotatably sleeved on multiple adjusting rods. A support roller is rotatably connected between two adjusting rods located at the same end.
[0007] Through the above technical solution, by providing an adjustable support component, the rotation of the bidirectional threaded rod can be controlled according to the diameter specifications of the parts to be welded. The corresponding adjustment rod can be moved relative to each other (increasing the height of the support roller) or moved away from each other (decreasing the height of the support roller) via the provided adjustment slider. This allows the corresponding support roller to effectively fit against the surfaces of the two parts to be welded, providing effective support at the weld joint and preventing displacement of the two parts at the joint during the welding process, which could lead to uneven welding and thus ensure welding quality.
[0008] Furthermore, the distance adjustment assembly includes two first moving screws, multiple positioning rods, and two transmission shafts. A first moving groove is formed in the middle of both sides of the upper end of the base. The two first moving screws are rotatably connected between the inner walls of the corresponding first moving grooves on both sides. Positioning grooves are formed near the front and rear of both sides of the upper end of the base. Multiple positioning rods are fixedly connected between the inner walls of the corresponding positioning grooves on both sides. A first moving slider is threaded onto the outer wall of each of the two first moving screws. Positioning sliders are slidably fitted onto the outer walls of the multiple positioning rods. The two first moving sliders and multiple positioning sliders are fixedly connected to the corresponding moving frame. A second motor is fixedly installed on both sides of the base. The two transmission shafts are rotatably connected to the corresponding moving frame. A rotating shaft is rotatably connected between the lower part of the inner walls of both sides of the two moving frames. A mounting frame is fixedly installed on both sides of the upper end of the base. A third motor is fixedly installed on one side of one of the moving frames.
[0009] Through the above technical solution, by providing a distance adjustment component, the first moving screw can be rotated according to the length specifications of the two parts to be welded. The first moving slider and the positioning slider can make the two moving frames move independently with the corresponding three-jaw chucks. The position of the corresponding three-jaw chucks can be adjusted according to the length specifications of the parts to be welded. With the help of the adjustable support component, it can stably clamp and fix various parts to be welded with different length specifications, effectively preventing the ends of the parts from bending and affecting the docking.
[0010] Furthermore, a fixed frame is fixedly connected to the upper rear of the base, an electric telescopic rod is fixedly installed at the upper end of the fixed frame, a lifting frame is fixedly connected to the telescopic end of the electric telescopic rod, a second moving groove is opened at the lower end of the lifting frame, a second moving screw is rotatably connected between the inner walls of the two sides of the second moving groove, a second moving slider is threaded onto the outer wall of the second moving screw, the welding gun is fixedly connected to the second moving slider, and the second moving slider is slidably disposed in the second moving groove;
[0011] The above technical solution allows for the adjustment of the height of the welding gun by activating the electric telescopic rod, enabling it to handle parts of different specifications and achieve effective welding operations. After the parts are placed, the horizontal position of the welding gun can be adjusted by controlling the rotation of the second moving screw and the second moving slider, thus aligning it with the area to be welded.
[0012] Furthermore, a connecting sleeve is movably sleeved on the outer wall of the two drive shafts. The inner wall of the connecting sleeve is provided with a slot at the top and bottom. A locking block is fixedly connected to the outer wall of the two drive shafts at the top and bottom. Multiple locking blocks are slidably arranged in the corresponding slots. A first gear is fixedly sleeved on the outer wall of the two rotating shafts. A second gear is fixedly sleeved on the outer wall of the two three-jaw chucks. The two first gears mesh with the corresponding second gears. One end of each of the two drive shafts passes through the corresponding movable frame and is fixedly connected to the corresponding rotating shaft. The connecting sleeve is rotatably sleeved on the two mounting frames.
[0013] Through the above technical solution, by controlling the rotation of one of the rotating shafts, the other rotating shaft can be rotated via the provided transmission shaft, connecting sleeve, clamping block and clamping groove. The two three-jaw chucks can be rotated synchronously via the provided first gear and second gear, thereby realizing the position rotation adjustment of the welding point.
[0014] Furthermore, a first motor is fixedly installed at the rear end of the adjustment frame, the output end of the first motor passes through the adjustment frame and is fixedly connected to the bidirectional threaded rod, and both adjustment sliders are slidably installed inside the adjustment frame;
[0015] Through the above technical solution, starting the first motor can cause the bidirectional threaded rod to rotate, thereby enabling the two adjusting sliders to move effectively within the adjusting frame.
[0016] Furthermore, the output ends of both second motors pass through the base and are fixedly connected to the corresponding first moving lead screw;
[0017] By using the above technical solution, the output end of the second motor is fixedly connected to the corresponding first moving lead screw, and the corresponding first moving lead screw can be rotated by starting the second motor.
[0018] Furthermore, the output end of the third motor passes through the corresponding movable frame and is fixedly connected to the corresponding rotating shaft;
[0019] By using the above technical solution, the output end of the third motor is fixedly connected to the corresponding rotating shaft, and the corresponding rotating shaft can be rotated by starting the third motor.
[0020] Furthermore, a fourth motor is fixedly installed on one side of the lifting frame, and the output end of the fourth motor passes through the lifting frame and is fixedly connected to the second moving lead screw;
[0021] The above technical solution involves providing a fourth motor and fixing the output end of the fourth motor to the second moving lead screw, thereby enabling the second moving lead screw to rotate by activating the fourth motor.
[0022] This utility model has the following beneficial effects:
[0023] 1. The present invention proposes an automatic welding equipment, which, by providing an adjustable support component, can control the rotation of a bidirectional threaded rod according to the diameter specifications of the parts to be welded. This, via an adjustable slider, allows the corresponding adjusting rods to move relative to each other (raising the height of the support rollers) or opposite to each other (lowering the height of the support rollers). This ensures that the corresponding support rollers can effectively adhere to the surfaces of the two parts to be welded, providing effective support at the weld joint. This prevents displacement at the joint of the two parts during welding, avoiding uneven welding and ensuring welding quality. The equipment achieves multi-specification adaptability of the support component at the weld joint, effectively improving production efficiency and welding quality.
[0024] 2. The automatic welding equipment proposed in this utility model, by providing a distance adjustment component, can control the rotation of the first moving screw according to the length specifications of the two parts to be welded. Through the provided first moving slider and positioning slider, the two moving frames carrying the corresponding three-jaw chucks can move independently. The position of the corresponding three-jaw chuck can be adjusted according to the length specifications of the parts to be welded. With the provided adjustable support component, it can stably clamp and fix the parts to be welded with various length specifications, effectively preventing the ends of the parts from bending and affecting the docking. Attached Figure Description
[0025] Figure 1 This is an isometric schematic diagram of an automatic welding equipment proposed in this utility model;
[0026] Figure 2 This is a front sectional view of an automatic welding equipment proposed in this utility model;
[0027] Figure 3 for Figure 2 Enlarged structural diagram at point A;
[0028] Figure 4 This is a side sectional view of an automatic welding equipment proposed in this utility model;
[0029] Figure 5 This is a top view schematic diagram of an automatic welding equipment proposed in this utility model.
[0030] Legend:
[0031] 1. Base; 2. Movable frame; 3. Welding gun; 4. Adjustable support assembly; 5. Distance adjustment assembly; 6. Three-jaw chuck; 7. Support frame; 8. Adjustment frame; 9. Bidirectional threaded rod; 10. Adjusting slider; 11. Adjusting rod; 12. Connecting shaft; 13. Support roller; 14. First motor; 15. First moving slot; 16. Positioning slot; 17. First moving screw; 18. Positioning rod; 19. First moving slider; 20. Positioning slider; 21. Second motor; 22. Drive shaft; 23. Connecting sleeve; 24. Slot; 25. Locking block; 26. Rotating shaft; 27. First gear; 28. Second gear; 29. Third motor; 30. Fixed frame; 31. Electric telescopic rod; 32. Lifting frame; 33. Second moving slot; 34. Second moving screw; 35. Second moving slider; 36. Fourth motor; 37. Mounting frame. Detailed Implementation
[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of specific embodiments. Obviously, the described specific embodiments are only a part of the specific embodiments of the present invention, and not all of them. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0033] Reference Figure 1-5This utility model provides a specific embodiment of an automatic welding device, comprising a base 1, a welding gun 3, and two movable frames 2. An adjustable support assembly 4 is provided between the welding gun 3 and the base 1, and a distance adjustment assembly 5 is provided between the two movable frames 2 and the base 1. A three-jaw chuck 6 is rotatably connected to the upper part of one side inner wall of each of the two movable frames 2. A fixed frame 30 is fixedly connected to the upper rear part of the base 1. An electric telescopic rod 31 is fixedly provided at the upper end of the fixed frame 30. A lifting frame 32 is fixedly connected to the telescopic end of the electric telescopic rod 31. A second moving groove 33 is opened at the lower end of the lifting frame 32. A second moving screw 34 is rotatably connected between the inner walls of the two sides of the second moving groove 33. A second moving slider 35 is threaded onto the outer wall of the second moving screw 34. The welding gun 3 is fixedly connected to the... The second movable slider 35 is slidably disposed in the second movable groove 33. The height position of the welding gun 3 can be adjusted by activating the electric telescopic rod 31 to accommodate parts of different specifications, thereby achieving effective welding operation. After the parts are placed, the horizontal position of the welding gun 3 can be adjusted by controlling the rotation of the second movable screw 34 via the second movable slider 35, so that it can be aligned with the place to be welded. A fourth motor 36 is fixedly disposed on one side of the lifting frame 32. The output end of the fourth motor 36 passes through the lifting frame 32 and is fixedly connected to the second movable screw 34. By providing the fourth motor 36 and fixing the output end of the fourth motor 36 to the second movable screw 34, the second movable screw 34 can be rotated by activating the fourth motor 36.
[0034] The adjustable support assembly 4 includes two support frames 7 and a connecting shaft 12. Both support frames 7 are fixedly connected to the base 1. An adjusting frame 8 is fixedly connected to the upper end of each support frame 7. A bidirectional threaded rod 9 is rotatably connected between the front and rear inner walls of the adjusting frame 8. Adjusting sliders 10 are threadedly fitted onto the front and rear ends of the outer wall of the bidirectional threaded rod 9. A first motor 14 is fixedly installed at the rear end of the adjusting frame 8. The output end of the first motor 14 passes through the adjusting frame 8 and is fixedly connected to the bidirectional threaded rod 9. Both adjusting sliders 10 are slidably disposed within the adjusting frame 8. Starting the first motor 14 causes the bidirectional threaded rod 9 to rotate, thereby allowing the two adjusting sliders 10 to move effectively within the adjusting frame 8. The upper ends of the two adjusting sliders 10... Both sides are hinged to adjust rods 11, and the connecting shaft 12 is rotatably sleeved on multiple adjust rods 11. Support rollers 13 are rotatably connected between two adjust rods 11 located at the same end. With the adjustable support assembly 4, the corresponding adjust rods 11 can be moved relative to each other (increasing the height of the support rollers 13) or moved away from each other (lowering the height of the support rollers 13) by controlling the rotation of the bidirectional threaded rod 9 according to the diameter of the parts to be welded. This is achieved through the adjustable slider 10, which allows the corresponding support rollers 13 to effectively fit against the surfaces of the two parts to be welded, providing effective support at the weld joint and preventing displacement of the two parts at the joint during welding, which could lead to uneven welding and thus ensure welding quality.
[0035] Reference Figure 1 , Figure 2 , Figure 4 and Figure 5The distance adjustment assembly 5 includes two first moving screws 17, multiple positioning rods 18, and two drive shafts 22. A first moving groove 15 is provided in the middle of both sides of the upper end of the base 1. The two first moving screws 17 are rotatably connected between the inner walls of the corresponding first moving grooves 15. Positioning grooves 16 are provided at the front and rear of both sides of the upper end of the base 1. Multiple positioning rods 18 are fixedly connected between the inner walls of the corresponding positioning grooves 16. A first moving slider 19 is threaded onto the outer wall of each of the two first moving screws 17. The output ends of two second motors 21 penetrate the base 1 and are fixedly connected to the corresponding first moving screws 17. By fixing the output ends of the second motors 21 to the corresponding first moving screws 17, the second motors can be started. 21 causes the corresponding first moving screw 17 to rotate. Positioning sliders 20 are slidably sleeved on the outer walls of multiple positioning rods 18. Two first moving sliders 19 and multiple positioning sliders 20 are fixedly connected to the corresponding moving frame 2. Second motors 21 are fixedly installed on both sides of the base 1. Two transmission shafts 22 are rotatably connected to the corresponding moving frame 2. Rotating shafts 26 are rotatably connected between the lower part of the inner walls on both sides of the two moving frames 2. Mounting brackets 37 are fixedly connected to both sides of the upper end of the base 1. A third motor 29 is fixedly installed on one side of one of the moving frames 2. By providing a distance adjustment component 5, the rotation of the first moving screw 17 can be controlled according to the length specifications of the two parts to be welded, via the provided first moving sliders 19 and positioning sliders 20. The two movable frames 2, along with their corresponding three-jaw chucks 6, can move independently. The position of the three-jaw chucks 6 can be adjusted according to the length of the workpiece to be welded, allowing them to work in conjunction with the adjustable support assembly 4 to stably clamp and fix workpieces of various lengths, effectively preventing bending of the parts' ends and affecting the welding process. Connecting sleeves 23 are movably fitted onto the outer walls of the two drive shafts 22. Slots 24 are provided on the upper and lower parts of the inner walls of the connecting sleeves 23. Locking blocks 25 are fixedly connected to the upper and lower parts of the outer walls of the two drive shafts 22, and multiple locking blocks 25 slide within their corresponding slots 24. First gears 27 are fixedly fitted onto the outer walls of the two rotating shafts 26, and second gears 28 are fixedly fitted onto the outer walls of the two three-jaw chucks 6. Both first gears 27 mesh with corresponding second gears 28. One end of each of the two drive shafts 22 passes through the corresponding movable frame 2 and is fixedly connected to the corresponding rotating shaft 26. The connecting sleeve 23 is rotatably mounted on the two mounting brackets 37. By controlling the rotation of one of the rotating shafts 26, the other rotating shaft 26 can be rotated via the provided drive shaft 22, connecting sleeve 23, locking block 25, and locking groove 24. The two three-jaw chucks 6 can then rotate synchronously via the provided first gears 27 and second gears 28, thereby realizing the positional adjustment of the welding point. The output end of the third motor 29 passes through the corresponding movable frame 2 and is fixedly connected to the corresponding rotating shaft 26.Then, the corresponding rotating shaft 26 can be rotated by activating the third motor 29.
[0036] Working Principle: In use, based on the length specifications of the two parts to be welded, the second motor 21 on the corresponding side is activated to rotate the first moving screw 17. This, along with the first moving slider 19 and positioning slider 20, allows the two moving frames 2 to move independently, carrying the corresponding three-jaw chucks 6. The position of the three-jaw chucks 6 can be adjusted according to the length specifications of the parts to be welded, allowing them to work in conjunction with the adjustable support assembly 4 to stably clamp and fix parts of various lengths, effectively preventing bending at the ends of the parts and affecting the welding process. Regarding the use of the adjustable support assembly 4, based on the diameter specifications of the parts to be welded, the first motor 14 is activated to rotate the bidirectional threaded rod 9. The adjusting slider 10 allows the corresponding adjusting rod 11 to move relative to each other (raising the height of the support roller 13) or move away from each other (lowering the height of the support roller 13). This ensures that the corresponding support roller 13 can effectively press against the surfaces of the two parts to be welded, providing effective support at the welding point and ensuring a smooth weld. In addition to ensuring quality, the design of the support roller 13 does not obstruct the rotation of the welded parts. Even when the three-jaw chuck 6 is controlling the rotation of the parts, it can ensure the smooth rotation of the parts and the smooth progress of the welding process. When the three-jaw chuck 6 is controlled to rotate, the corresponding rotating shaft 26 can be rotated by starting the third motor 29. Through the provided transmission shaft 22, connecting sleeve 23, chuck block 25 and chuck groove 24, the rotating shaft 26 on the other side can be rotated. Through the provided first gear 27 and second gear 28, the two three-jaw chucks 6 can be rotated synchronously, thereby realizing the position adjustment of the welding point. During the welding process, the height of the welding gun 3 can be adjusted by starting the electric telescopic rod 31 to accommodate parts of different specifications, thereby achieving effective welding operation. At the same time, after the parts are placed, the second moving screw 34 can be rotated by controlling the starting of the fourth motor 36. Through the provided second moving slider 35, the horizontal position of the welding gun 3 can be adjusted so that it can be aligned with the part to be welded.
[0037] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing specific embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. An automatic welding device, comprising a base (1), a welding gun (3), and two movable frames (2), characterized in that: An adjustable support assembly (4) is provided between the welding gun (3) and the base (1), and a distance adjustment assembly (5) is provided between the two movable frames (2) and the base (1). A three-jaw chuck (6) is rotatably connected to the upper part of the inner wall of one side of each of the two movable frames (2). The adjustable support assembly (4) includes two support frames (7) and a connecting shaft (12). The two support frames (7) are fixedly connected to the base (1). An adjusting frame (8) is fixedly connected to the upper end of the two support frames (7). A bidirectional threaded rod (9) is rotatably connected between the front and rear inner walls of the adjusting frame (8). An adjusting slider (10) is threadedly sleeved on the front and rear sides of the outer wall of the bidirectional threaded rod (9). An adjusting rod (11) is hinged to both sides of the upper end of the two adjusting sliders (10). The connecting shaft (12) is rotatably sleeved on multiple adjusting rods (11). A support roller (13) is rotatably connected between two adjusting rods (11) located at the same end.
2. The welding equipment for automatic welding according to claim 1, characterized in that: The distance adjustment assembly (5) includes two first moving screws (17), multiple positioning rods (18), and two drive shafts (22). The upper end of the base (1) has two first moving grooves (15) at the center of both sides. The two first moving screws (17) are rotatably connected between the inner walls of the corresponding first moving grooves (15). The upper end of the base (1) has two positioning grooves (16) at the front and rear of both sides. The multiple positioning rods (18) are fixedly connected between the inner walls of the corresponding positioning grooves (16). The outer walls of the two first moving screws (17) are threaded with first moving sliders (19). Positioning sliders (20) are slidably sleeved on the outer walls of multiple positioning rods (18). Two first movable sliders (19) and multiple positioning sliders (20) are fixedly connected to the corresponding movable frame (2). Second motors (21) are fixedly installed on both sides of the base (1). Two transmission shafts (22) are rotatably connected to the corresponding movable frame (2). Rotating shafts (26) are rotatably connected between the inner walls on both sides of the two movable frames (2) at the lower part. Mounting brackets (37) are fixedly connected to both sides of the upper end of the base (1). A third motor (29) is fixedly installed on one side of one of the movable frames (2).
3. The welding equipment for automatic welding according to claim 1, characterized in that: A fixed frame (30) is fixedly connected to the upper rear of the base (1). An electric telescopic rod (31) is fixedly installed at the upper end of the fixed frame (30). A lifting frame (32) is fixedly connected to the telescopic end of the electric telescopic rod (31). A second moving groove (33) is opened at the lower end of the lifting frame (32). A second moving screw (34) is rotatably connected between the inner walls of the two sides of the second moving groove (33). A second moving slider (35) is threaded onto the outer wall of the second moving screw (34). The welding gun (3) is fixedly connected to the second moving slider (35). The second moving slider (35) is slidably disposed in the second moving groove (33).
4. The welding equipment for automatic welding according to claim 2, characterized in that: A connecting sleeve (23) is movably fitted on the outer wall of the two drive shafts (22). The inner wall of the connecting sleeve (23) is provided with a slot (24) at the top and bottom. A locking block (25) is fixedly connected to the outer wall of the two drive shafts (22) at the top and bottom. Multiple locking blocks (25) are slidably arranged in the corresponding slot (24). The outer wall of the two rotating shafts (26) is fixedly fitted with a first gear (27). The outer wall of the two three-jaw chucks (6) is fixedly fitted with a second gear (28). The two first gears (27) mesh with the corresponding second gears (28). One end of the two drive shafts (22) passes through the corresponding moving frame (2) and is fixedly connected to the corresponding rotating shaft (26). The connecting sleeve (23) is rotatably fitted on the two mounting frames (37).
5. The welding equipment for automatic welding according to claim 1, characterized in that: The rear end of the adjustment frame (8) is fixedly provided with a first motor (14). The output end of the first motor (14) passes through the adjustment frame (8) and is fixedly connected to the bidirectional threaded rod (9). Both adjustment sliders (10) are slidably disposed inside the adjustment frame (8).
6. The welding equipment for automatic welding according to claim 2, characterized in that: The output ends of the two second motors (21) pass through the base (1) and are fixedly connected to the corresponding first moving lead screw (17).
7. The welding equipment for automatic welding according to claim 2, characterized in that: The output end of the third motor (29) passes through the corresponding movable frame (2) and is fixedly connected to the corresponding rotating shaft (26).
8. The welding equipment for automatic welding according to claim 3, characterized in that: A fourth motor (36) is fixedly installed on one side of the lifting frame (32). The output end of the fourth motor (36) passes through the lifting frame (32) and is fixedly connected to the second moving lead screw (34).