Battery appearance detection device

Abstract

The utility model provides a battery appearance detection device, which is arranged above a transmission belt, is used for detecting a welding area between a top cover and a shell of a battery on the transmission belt, and comprises a mounting plate, a distance adjusting mechanism, a first detection mechanism, a second detection mechanism and a third detection mechanism, the distance adjusting mechanism and the first detection mechanism are arranged on the mounting plate, the distance adjusting mechanism is used for adjusting the distance between the first detection mechanism and the second detection mechanism, and the first detection mechanism and the second detection mechanism are used for detecting a welding area between a top cover and a shell of a battery; and the third detection mechanism is used for detecting a welding area between the top cover of the battery and the sealing nail. According to the battery appearance detection device provided by the utility model, the two-dimensional image and the three-dimensional image of the welding area between the top cover of the battery and the shell of the battery can be acquired by the battery appearance detection device, and the two-dimensional image and the three-dimensional image of the welding area between the top cover of the battery and the sealing nail can be acquired by the battery appearance detection device.

Description

Technical Field

[0001] This utility model relates to the field of battery testing technology, specifically to a battery appearance testing device. Background Technology

[0002] With the rapid development of new energy vehicles and energy storage systems, the production quality and safety of power batteries have received widespread attention. Battery welding, as a key process in battery manufacturing, directly affects the structural integrity, reliability, safety, and performance of the battery. However, in existing technologies, various welding defects can still occur after battery welding, such as poor welding, incomplete weld circles, incomplete welds, weld misalignment, weld trajectories extending beyond the edge of the terminal post, excessively large pits, and incomplete welds. These problems not only affect the battery's electrical performance but may also lead to safety hazards such as leakage, short circuits, and even fires.

[0003] Traditional welding defect detection processes primarily rely on manual visual inspection, a method with significant limitations. First, manual inspection is inefficient and unsuitable for large-scale production. Second, the results are highly dependent on the operator's experience and subjective judgment; significant differences in skill levels among personnel lead to inconsistent inspection outcomes. Furthermore, manual inspection struggles to detect minute welding defects, easily resulting in missed defects and impacting the overall battery quality. Utility Model Content

[0004] This invention provides a battery appearance inspection device to solve the problems of slow manual battery inspection and difficulty in detecting minute welding defects in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a battery appearance inspection device, disposed above a conveyor belt, for inspecting the welding area between the top cover and the casing of a battery on the conveyor belt. The battery appearance inspection device includes a mounting plate, a spacing adjustment mechanism, a first inspection mechanism, a second inspection mechanism, and a third inspection mechanism. The spacing adjustment mechanism and the first inspection mechanism are disposed on the mounting plate. The spacing adjustment mechanism is used to adjust the distance between the first inspection mechanism and the second inspection mechanism. The first inspection mechanism and the second inspection mechanism are used to inspect the welding area between the top cover and the casing of the battery. The third inspection mechanism is used to inspect the welding area between the top cover and the sealing nail of the battery.

[0006] Both the first and second testing mechanisms include a first mounting base. A first planar camera is mounted on the first mounting base with its line of sight facing downwards. The first planar camera is used to acquire a two-dimensional image of the battery on a plane parallel to the battery's direction of movement. A reflector is also mounted on the first mounting base below the first planar camera. The reflector is used to change the optical path of the first planar camera so that the first planar camera can acquire a two-dimensional image of the weld joint on the side of the battery parallel to the battery's direction of movement. A first stereo camera is mounted on the first mounting base. The first stereo camera is used to acquire a three-dimensional image of the weld joint between the surface of the battery captured by the first planar camera and the top cover surface of the battery.

[0007] The third testing mechanism includes a second mounting base mounted on a mounting plate, a second planar camera mounted on the second mounting base with its line of sight facing downwards, the second planar camera being used to acquire two-dimensional images of the battery top cover, a second stereo camera mounted on the second mounting base, the second stereo camera being used to acquire three-dimensional images of the weld between the battery top cover and the sealing nail, and a dome light source being mounted on the second mounting base.

[0008] Furthermore, the dome light source includes a lampshade located below the second mounting base, with LED beads installed inside the lampshade. The opening of the lampshade faces downward, and the axis of the lampshade is parallel to the direction of movement of the battery. A through hole is formed on the lampshade to allow the light path of the second planar camera to pass through.

[0009] Furthermore, the first stereo camera is mounted on the first mounting base via a dual-angle adjustment component. The dual-angle adjustment component can adjust the tilt angle between the ray of the first stereo camera and the plane parallel to the direction of battery movement, and can also adjust the tilt angle between the ray of the first stereo camera and the horizontal plane.

[0010] Furthermore, the dual-angle adjustment assembly includes a first hinge seat, a first rotating frame, a second hinge seat, and a second rotating frame. The first hinge seat is disposed on the first mounting base, and the first rotating frame is hinged to the first hinge seat and can rotate in a vertical plane. A first adjusting block is disposed on the first rotating frame. A first screw fixing seat is disposed on both sides of the first adjusting block on the first hinge seat. A first adjusting screw is disposed on the first screw fixing seat, and one end of the first adjusting screw abuts against the first adjusting block.

[0011] The second hinge seat is located at the bottom of the first rotating frame. The second rotating frame is hinged to the second hinge seat and can rotate in a plane perpendicular to the rotation plane of the first rotating frame. The second rotating frame is provided with a second adjusting block. The second hinge seat is provided with two second screw fixing seats located on both sides of the second adjusting block. The second screw fixing seats are provided with second adjusting screws, and one end of the second adjusting screw abuts against the second adjusting block.

[0012] Furthermore, the spacing adjustment mechanism includes a bidirectional lead screw with opposite threads and a drive unit mounted on the mounting plate. The threads at both ends of the bidirectional lead screw are in opposite directions, and the bidirectional lead screw is rotatably connected to the bottom of the mounting plate. Each of the two first mounting seats is provided with a nut that is threadedly connected to the bidirectional lead screw, and the two first mounting seats are respectively mounted at both ends of the bidirectional lead screw through the nuts, so that when the bidirectional lead screw rotates, it drives the two first mounting seats to move relative to each other. The output end of the drive unit is connected to the bidirectional lead screw, and the drive unit is used to drive the bidirectional lead screw to rotate. The spacing adjustment mechanism also includes a limiting component that restricts the rotation of the first mounting seats.

[0013] Furthermore, the limiting component includes a limiting guide rail disposed on the mounting plate and a limiting seat disposed on the first mounting base, wherein the limiting guide rail is parallel to the bidirectional lead screw with forward and reverse threads, and the limiting seat is sleeved on the limiting guide rail.

[0014] The beneficial effects of this utility model are as follows:

[0015] The battery appearance inspection device provided by this utility model, through the setting of a spacing adjustment mechanism, a first inspection mechanism, a second inspection mechanism and a third inspection mechanism, enables the battery appearance inspection device to acquire two-dimensional and three-dimensional images of the welding area between the top cover and the battery casing of the battery, as well as two-dimensional and three-dimensional images of the welding area between the top cover and the sealing nail of the battery, thereby detecting welding appearance defects of the battery. Attached Figure Description

[0016] Figure 1 A perspective view of a battery appearance inspection device;

[0017] Figure 2 This is a schematic diagram of the spacing adjustment mechanism;

[0018] Figure 3 This is a schematic diagram of the structure of the first testing institution;

[0019] Figure 4 This is a schematic diagram of the structure of the third testing institution;

[0020] Figure 5 A 3D view of the dual-angle adjustment component;

[0021] Figure 6 A 3D view of the other angle of the dual-angle adjustment component;

[0022] Figure 7 This is a cross-sectional view of the lampshade.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Mounting plate; 2. Spacing adjustment mechanism; 21. Bidirectional lead screw (positive and negative threads); 22. Drive unit; 23. Limiting assembly; 231. Limiting guide rail; 232. Limiting seat; 3. First detection mechanism; 31. First mounting base; 32. First planar camera; 33. Reflector; 34. First stereo camera; 35. Dual-angle adjustment assembly; 351. First hinge seat; 3511. First screw fixing seat; 3512. First adjusting screw; 352. First rotating frame; 3521, First adjusting block; 353, Second hinge seat; 3531, Second screw fixing seat; 3532, Second adjusting screw; 354, Second rotating frame; 3541, Second adjusting block; 4, Second detection mechanism; 5, Third detection mechanism; 51, Second mounting base; 52, Second planar camera; 53, Second stereo camera; 54, Dome light source; 541, Lampshade; 542, Through hole; 543, Lamp bead; 6, Battery. Detailed Implementation

[0025] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0026] like Figure 1-7 As shown, this utility model embodiment provides a battery appearance inspection device, which is set above a conveyor belt and is used to inspect the welding area between the top cover and the shell of the battery 6 on the conveyor belt. The battery appearance inspection device includes a mounting plate 1, a spacing adjustment mechanism 2, a first inspection mechanism 3, a second inspection mechanism 4 and a third inspection mechanism 5. The spacing adjustment mechanism 2 and the first inspection mechanism 3 are set on the mounting plate 1. The spacing adjustment mechanism 2 is used to adjust the distance between the first inspection mechanism 3 and the second inspection mechanism 4. The first inspection mechanism 3 and the second inspection mechanism 4 are used to inspect the welding area between the top cover and the shell of the battery 6. The third inspection mechanism 5 is used to inspect the welding area between the top cover and the sealing nail of the battery 6.

[0027] Both the first testing mechanism 3 and the second testing mechanism 4 include a first mounting base 31. A first planar camera 32 is mounted on the first mounting base 31 with its line of sight facing downwards. The first planar camera 32 is used to acquire two-dimensional images of the battery 6 and the plane parallel to the direction of movement of the battery 6. A reflector 33 is also mounted on the first mounting base 31 below the first planar camera 32. The reflector 33 is used to change the optical path of the first planar camera 32 so that the first planar camera 32 can acquire two-dimensional images of the welding joint on the side of the battery 6 parallel to the direction of movement of the battery 6. A first stereo camera 34 is mounted on the first mounting base 31. The first stereo camera 34 is used to acquire three-dimensional images of the welding joint between the surface of the battery 6 captured by the first planar camera 32 and the top cover surface of the battery 6.

[0028] The third detection mechanism 5 includes a second mounting base 51 mounted on the mounting plate 1. A second planar camera 52 is mounted on the second mounting base 51 with its line of sight facing downwards (in a specific embodiment, the first planar camera 32 and the second planar camera 52 have 5 million pixels, a field of view of 36*30mm, a camera resolution of 2448*2048 pixels, a camera frame rate of 24.2fps, a single pixel accuracy of 0.02mm / pixel, and a detection accuracy of 0.1mm). The second planar camera 52 is used to acquire two-dimensional images of the top cover of the battery 6. A second stereo camera 53 is mounted on the second mounting base 51. The second stereo camera 53 is used to acquire three-dimensional images of the weld between the top cover of the battery 6 and the sealing nail (in a specific embodiment, the first stereo camera 34 and the second stereo camera 53 are model LJ-X8200 or LJ-X8080). A dome light source 54 is also mounted on the second mounting base 51.

[0029] like Figure 7 As shown, the dome light source 54 includes a lampshade 541 disposed below the second mounting base 51. An LED bead 543 is disposed inside the lampshade 51. The opening of the lampshade 541 faces downward, and the axis of the lampshade 541 is parallel to the direction of movement of the battery 6, thereby reducing the scattering of light emitted by the LED bead 543 and improving the light utilization rate. A through hole 542 is formed on the lampshade 541 to allow the light path of the second planar camera 52 to pass through.

[0030] In order to make the shooting angle of the first stereo camera 34 wider and to make the first stereo camera 34 better aligned with the position to be captured, in a preferred embodiment of the present invention, the first stereo camera 34 is mounted on the first mounting base 31 by means of a dual-angle adjustment component 35. The dual-angle adjustment component 35 can adjust the tilt angle between the ray of the first stereo camera 34 and the plane parallel to the moving direction of the battery 6, and can also adjust the tilt angle between the ray of the first stereo camera 34 and the horizontal plane.

[0031] like Figure 5-6 As shown, the dual-angle adjustment assembly 35 includes a first hinge seat 351, a first rotating frame 352, a second hinge seat 353, and a second rotating frame 354. The first hinge seat 351 is disposed on the first mounting base 31. The first rotating frame 352 is hinged to the first hinge seat 351 and can rotate in the vertical plane. A first adjusting block 3521 is disposed on the first rotating frame 352. A first screw fixing seat 3511 is disposed on both sides of the first adjusting block 3521 on the first hinge seat 351. A first adjusting screw 3512 is disposed on the first screw fixing seat 3511, and one end of the first adjusting screw 3512 abuts against the first adjusting block 3521.

[0032] The second hinge seat 353 is disposed at the bottom of the first rotating frame 352. The second rotating frame 354 is hinged to the second hinge seat 353 and can rotate in a plane perpendicular to the rotation plane of the first rotating frame 352. The second rotating frame 354 is provided with a second adjusting block 3541. The second hinge seat 353 is provided with two second screw fixing seats 3531 located on both sides of the second adjusting block 3541. The second screw fixing seats 3531 are provided with second adjusting screws 3532, and one end of the second adjusting screws 3532 abuts against the second adjusting block 3541.

[0033] When it is necessary to adjust the angle of the first stereo camera 34, the relative positions of the first hinge seat 351 and the first rotating frame 352 are changed by rotating the first adjusting screw 3512, and the relative positions of the second hinge seat 353 and the second rotating frame 354 are changed by rotating the second adjusting screw 3532. This changes the position of the first stereo camera 34, that is, it adjusts the tilt angle of the ray of the first stereo camera 34 with the plane parallel to the direction of movement of the battery 6, and adjusts the tilt angle of the ray of the first stereo camera 34 with the horizontal plane, so as to change the angle of the output end of the first stereo camera 34.

[0034] This utility model is used to detect the welding area between the top cover and the casing of battery 6, and the welding area between the top cover and the sealing nail of battery 6. The welding appearance defects that can be detected include: welding pits (pit depth ≥ 0.2mm, pit diameter ≥ 0.2mm, number of pits), welding bursts (burst depth ≥ 0.2mm, burst diameter ≥ 0.2mm, number of bursts), welding pinholes (pinhole depth ≥ 0.2mm, pinhole diameter ≥ 0.2mm, number of pinholes, pinhole location), wavy edges (wavy edge height ≥ 0.2mm), protrusions (protrusion height ≥ 0.2mm, protrusion diameter ≥ 0.2mm), weld line offset (weld seam protruding above the casing surface ≥ 0.2mm), weld line length (weld break distance > 0.2mm), and weld line width (height > 0.2mm).

[0035] Specifically, in the battery appearance inspection device of this utility model, the detection of welding defects is determined by combining the two-dimensional images acquired by the first planar camera 32 and the second planar camera 52 and the three-dimensional images acquired by the first stereo camera 34 and the second stereo camera 53.

[0036] Specifically, the distance between the first detection mechanism 3 and the second detection mechanism 4 is adjusted by the spacing adjustment mechanism 2, and the position of the first stereo camera 34 is adjusted by the dual-angle adjustment component 35 so that the first stereo camera 34 is aligned with the test position of the battery 6. The dome light source 54 is activated, and the first planar camera 32, the second planar camera 52, the first stereo camera 34, and the second stereo camera 53 are also activated. The first planar camera 32 acquires a two-dimensional image of the weld joint on the side of the battery 6 parallel to the direction of movement of the battery 6 through the reflector 33. The first stereo camera 34 acquires a three-dimensional image of the weld joint between the surface of the battery 6 captured by the first planar camera 32 and the top cover surface of the battery 6. The second planar camera 52 acquires a two-dimensional image of the weld joint between the top cover and the sealing nail, and the second stereo camera 53 acquires a three-dimensional image of the weld joint between the top cover and the sealing nail. By combining the two-dimensional and three-dimensional images, a comprehensive and systematic detection of welding defects in the battery 6 can be achieved. By changing the relative position of the battery 6 and the battery appearance inspection device, the detection of welding defects at both ends of the battery 6 can finally be completed. Through the above settings, not only can the efficiency of welding defect detection in the battery 6 be improved, but the two-dimensional combined with three-dimensional image detection method can also more comprehensively detect the problems existing in the welding defects, thereby improving product quality.

[0037] For solder wire offset, solder wire length, and solder wire width, a two-dimensional image captured by the first planar camera 32 and the second planar camera 52 can be used for a first judgment, and a three-dimensional image captured by the first stereo camera 34 and the second stereo camera 53 can be used for a second judgment. If both judgments are qualified, a qualified result is output. For defects in depth and height, such as bumps and pits, suspected defects can be marked on the two-dimensional image, and the three-dimensional image can be further judged.

[0038] The spacing adjustment mechanism 2 includes a bidirectional lead screw 21 with opposite threads and a drive unit 22 mounted on the mounting plate 1. The threads at both ends of the bidirectional lead screw 21 are in opposite directions, and the bidirectional lead screw 21 is rotatably connected to the bottom of the mounting plate 1. Each of the two first mounting seats 31 is provided with a nut that is threadedly connected to the bidirectional lead screw 21, and the two first mounting seats 31 are respectively mounted at both ends of the bidirectional lead screw 21 through the nuts, so that when the bidirectional lead screw 21 rotates, it drives the two first mounting seats 31 to move relative to each other. The output end of the drive unit 22 is connected to the bidirectional lead screw 21 with forward and reverse teeth. The drive unit 22 is used to drive the bidirectional lead screw 21 with forward and reverse teeth to rotate. The pitch adjustment mechanism 2 also includes a limiting component 23 that limits the rotation of the first mounting base 31 (in a specific embodiment, the limiting component 23 includes a limiting guide rail 231 disposed on the mounting plate 1 and a limiting seat 232 disposed on the first mounting base 31, and the limiting guide rail 231 is parallel to the bidirectional lead screw 21 with forward and reverse teeth, and the limiting seat 232 is sleeved on the limiting guide rail 231).

[0039] Specifically, the drive unit 22 includes a servo motor and a belt drive mechanism. The servo motor is mounted on the mounting plate 1, and the output end of the servo motor is connected to the bidirectional screw 21 with forward and reverse threads through the belt drive mechanism. When it is necessary to adjust the distance between the first detection mechanism 3 and the second detection mechanism 4, the drive unit 22 drives the bidirectional screw 21 with forward and reverse threads to rotate. Through the cooperation between the bidirectional screw 21 with the nut, the first detection mechanism 3 and the second detection mechanism 4 are driven to move relative to each other on the bidirectional screw 21, so as to move closer to each other or further away from each other, thereby adjusting the distance between the first detection mechanism 3 and the second detection mechanism 4. The limiting component 23 prevents the first detection mechanism 3 and the second detection mechanism 4 from rotating on the bidirectional screw 21 with forward and reverse threads.

[0040] In summary, this battery appearance inspection device, through the spacing adjustment mechanism 2, the first inspection mechanism 3, the second inspection mechanism 4, and the third inspection mechanism 5, enables the battery appearance inspection device to acquire two-dimensional and three-dimensional images of the welding area between the top cover and the casing of the battery 6, as well as two-dimensional and three-dimensional images of the welding area between the top cover and the sealing nail of the battery 6, thereby detecting welding appearance defects of the battery 6.

[0041] The embodiments described above merely illustrate the implementation of this utility model, and should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A battery appearance inspection device, disposed above a conveyor belt, for inspecting the welded area between the top cover and the casing of a battery on the conveyor belt, characterized in that, The battery appearance inspection device includes a mounting plate (1), a spacing adjustment mechanism (2), a first inspection mechanism (3), a second inspection mechanism (4), and a third inspection mechanism (5). The spacing adjustment mechanism (2) and the first inspection mechanism (3) are mounted on the mounting plate (1). The spacing adjustment mechanism (2) is used to adjust the distance between the first inspection mechanism (3) and the second inspection mechanism (4). The first inspection mechanism (3) and the second inspection mechanism (4) are used to inspect the welding area between the top cover and the shell of the battery (6). The third inspection mechanism (5) is used to inspect the welding area between the top cover and the sealing nail of the battery (6). Both the first testing mechanism (3) and the second testing mechanism (4) include a first mounting base (31). A first planar camera (32) is mounted on the first mounting base (31) with its line of sight facing downwards. The first planar camera (32) is used to acquire two-dimensional images of the battery (6) and the plane parallel to the direction of movement of the battery (6). A reflector (33) is also mounted on the first mounting base (31) below the first planar camera (32). The reflector (33) is used to change the optical path of the first planar camera (32) so that the first planar camera (32) can acquire two-dimensional images of the welding joint on the side of the battery (6) parallel to the direction of movement of the battery (6). A first stereo camera (34) is mounted on the first mounting base (31). The first stereo camera (34) is used to acquire three-dimensional images of the welding joint between the surface of the battery (6) captured by the first planar camera (32) and the top cover surface of the battery (6). The third testing mechanism (5) includes a second mounting base (51) set on the mounting plate (1), a second planar camera (52) set on the second mounting base (51) with its line of sight facing downwards, the second planar camera (52) is used to acquire two-dimensional images of the top cover of the battery (6), a second stereo camera (53) is set on the second mounting base (51), the second stereo camera (53) is used to acquire three-dimensional images of the weld between the top cover of the battery (6) and the sealing nail, and a dome light source (54) is also set on the second mounting base (51).

2. The battery appearance inspection device according to claim 1, characterized in that, The dome light source (54) includes a lampshade (541) disposed below the second mounting base (51), and an LED (543) is disposed inside the lampshade (51). The opening of the lampshade (541) faces downward, and the axis of the lampshade (541) is parallel to the direction of movement of the battery (6). A through hole (542) is formed on the lampshade (541) to allow the light path of the second planar camera (52) to pass through.

3. The battery appearance inspection device according to claim 1, characterized in that, The first stereo camera (34) is mounted on the first mounting base (31) via a dual-angle adjustment component (35). The dual-angle adjustment component (35) can adjust the tilt angle between the ray of the first stereo camera (34) and the plane parallel to the moving direction of the battery (6), and can also adjust the tilt angle between the ray of the first stereo camera (34) and the horizontal plane.

4. The battery appearance inspection device according to claim 3, characterized in that, The dual-angle adjustment assembly (35) includes a first hinge seat (351), a first rotating frame (352), a second hinge seat (353), and a second rotating frame (354). The first hinge seat (351) is disposed on the first mounting base (31). The first rotating frame (352) is hinged to the first hinge seat (351) and can rotate in the vertical plane. A first adjusting block (3521) is disposed on the first rotating frame (352). A first screw fixing seat (3511) is disposed on both sides of the first adjusting block (3521) on the first hinge seat (351). A first adjusting screw (3512) is disposed on the first screw fixing seat (3511), and one end of the first adjusting screw (3512) abuts against the first adjusting block (3521). The second hinge seat (353) is located at the bottom of the first rotating frame (352). The second rotating frame (354) is hinged to the second hinge seat (353) and can rotate in a plane perpendicular to the rotation plane of the first rotating frame (352). The second rotating frame (354) is provided with a second adjusting block (3541). The second hinge seat (353) is provided with two second screw fixing seats (3531) located on both sides of the second adjusting block (3541). The second screw fixing seat (3531) is provided with a second adjusting screw (3532), and one end of the second adjusting screw (3532) abuts against the second adjusting block (3541).

5. The battery appearance inspection device according to claim 1, characterized in that, The pitch adjustment mechanism (2) includes a bidirectional screw (21) with positive and negative threads and a drive unit (22) mounted on the mounting plate (1). The threads at both ends of the bidirectional screw (21) are opposite in direction, and the bidirectional screw (21) is rotatably connected to the bottom of the mounting plate (1). Each of the two first mounting seats (31) is provided with a nut that is threadedly connected to the bidirectional screw (21), and the two first mounting seats (31) are respectively mounted at both ends of the bidirectional screw (21) with the nuts, so that when the bidirectional screw (21) rotates, it drives the two first mounting seats (31) to move relative to each other. The output end of the drive unit (22) is connected to the bidirectional screw (21), and the drive unit (22) is used to drive the bidirectional screw (21) to rotate. The pitch adjustment mechanism (2) also includes a limiting component (23) that limits the rotation of the first mounting seats (31).

6. The battery appearance inspection device according to claim 5, characterized in that, The limiting component (23) includes a limiting guide rail (231) disposed on the mounting plate (1) and a limiting seat (232) disposed on the first mounting base (31), wherein the limiting guide rail (231) is parallel to the bidirectional lead screw (21) with positive and negative threads, and the limiting seat (232) is sleeved on the limiting guide rail (231).

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