Movable visual inspection mechanism

Abstract

The invention discloses a movable visual inspection mechanism, and relates to the technical field of visual inspection, the movable visual inspection mechanism comprises a support frame, the inner side of the support frame is rotatably connected with a first connecting plate, the bottom of the first connecting plate is movably connected with an arc-shaped frame, and the inner side of the arc-shaped frame is movably connected with a visual inspection camera; a multi-stage telescopic mechanism for a visual inspection camera is arranged between the first connecting plate and the arc-shaped frame, and comprises a first adjusting plate, a second adjusting plate and a third adjusting rod which are arranged between the first connecting plate and the arc-shaped frame; the first adjusting plate, the second adjusting plate and the third adjusting rod achieve vertical translation of the visual detection camera through vertical stretching and retracting of the first adjusting plate, the second adjusting plate and the third adjusting rod, the position of the visual detection camera can be moved and adjusted at multiple angles for detection, it can be ensured that complete image information of a to-be-detected object is captured from multiple visual angles, and therefore the detection precision and accuracy are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of visual inspection, and in particular to a movable visual inspection mechanism. Background Art

[0002] Visual inspection is a device that uses computer vision technology to achieve automated inspection and identification. It collects and analyzes image data to determine whether the target meets the specified standards. It can quickly detect and analyze a large amount of image data, thereby achieving real-time monitoring of product quality on the production line. This greatly improves production efficiency and reduces delays and errors caused by manual inspection.

[0003] After searching, the invention patent with Chinese patent number CN118603995A discloses a product visual inspection device. Compared with the prior art, the invention patent with Chinese patent number CN118603995A can make the gears and racks design so that when the conveying device drives the product to move, the gears and racks can make the product flip over to complete the reverse design, which does not require manual operation and can save time in the inspection work.

[0004] However, in actual use of the above device, the position of the detection device is fixed. If objects to be detected have different shapes, it is difficult to capture complete image information of the objects to be detected from multiple perspectives, resulting in low accuracy and precision of the detection. Therefore, a movable visual detection mechanism is proposed. Summary of the invention

[0005] The purpose of the present invention is to solve the problem in the prior art that it is difficult to capture complete image information of an object to be inspected from multiple viewing angles, thereby resulting in low detection accuracy, and to propose a movable visual inspection mechanism.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A movable visual inspection mechanism, comprising a support frame, wherein a first connecting plate is rotatably connected to the inner side of the support frame, an arc frame movably connected to the bottom of the first connecting plate is installed, a visual inspection camera is movably connected to the inner side of the arc frame, a multi-stage telescopic mechanism for the visual inspection camera is commonly arranged between the first connecting plate and the arc frame, the multi-stage telescopic mechanism comprises a first adjustment plate, a second adjustment plate and a third adjustment rod commonly arranged between the first connecting plate and the arc frame, and the first adjustment plate, the second adjustment plate and the third adjustment rod realize the up and down translation of the visual inspection camera by their own up and down extension;

[0008] The arc frame is provided with an arc moving mechanism for a visual inspection camera, and the arc moving mechanism includes a third rotating rod and a fourth rotating rod rotatably connected to the inner side of the arc frame, and the outer sides of the third rotating rod and the fourth rotating rod are jointly sleeved with a second transmission belt. The rotation of the second transmission belt itself enables the visual inspection camera to move in an arc along the arc frame. The inner side of the arc frame is movably connected with an arc plate, and the side surfaces of the arc plate are movably provided with a plurality of limit rods for limiting the visual inspection camera. The position of the visual inspection camera can be adjusted by moving at multiple angles for inspection, which can ensure that the complete image information of the object to be inspected is captured from multiple viewing angles, thereby improving the precision and accuracy of the inspection.

[0009] The above technical solution further includes:

[0010] A first open groove is provided on the upper part of the support frame, and a first worm gear is rotatably connected to the inner side of the first open groove. A round rod is installed at the bottom of the first worm gear, and the round rod is rotatably connected to the support frame. One end of the round rod away from the first worm gear is fixedly connected to the first connecting plate.

[0011] A first worm is rotatably connected to the inner side of the first opening slot, a first servo motor is installed on the side of the support frame, and the output end of the first servo motor extending to the inner side of the first opening slot is fixedly connected to the first worm.

[0012] The first adjustment plate is installed at one end of the first connecting plate away from the round rod, the second adjustment plate is slidably arranged on the inner side of the first adjustment plate, a second servo motor is installed on the upper part of the first adjustment plate, and a first threaded rod is installed on the output end of the second servo motor extending to the inner side of the first adjustment plate, the first threaded rod is rotatably connected to the first adjustment plate, and the first threaded rod is threadedly connected to the second adjustment plate.

[0013] The inner side of the second adjustment plate is rotatably connected with the first rotating rod and the second rotating rod respectively, the outer sides of the first rotating rod and the second rotating rod are jointly sleeved with a first transmission belt, the outer side of the first rotating rod is installed with a first gear, the inner side of the first adjustment plate is installed with a first rack, and the first gear is meshed with the first rack.

[0014] The third adjustment rod is slidably arranged on the inner side of the second adjustment plate, a second rack is installed on the side of the second adjustment plate, a second gear is installed on the outer side of the second rotating rod, and the second gear is meshed with the second rack. Through multi-stage adjustment, the maximum degree of adjustment can be achieved within a limited space, and it is applicable even to higher and lower objects to be detected.

[0015] A second worm gear is installed on the outer side of the third rotating rod, and a second worm is rotatably connected to the inner side of the arc frame, and the second worm is meshed with the second worm gear. A fourth servo motor is installed on the side of the arc frame, and the output end of the fourth servo motor extending to the inner side of the arc frame is fixedly connected to the second worm. A plurality of support rods are rotatably connected to the inner side of the arc frame, and the plurality of support rods are movably connected to the second transmission belt. A second connecting plate is installed on the outer side of the second transmission belt, and an end of the second connecting plate away from the second transmission belt is fixedly connected to the visual detection camera.

[0016] An arc-shaped groove is installed on the side of the arc-shaped frame, and a first sliding block is slidably arranged inside the arc-shaped groove. The first sliding block is fixedly connected to the second connecting plate.

[0017] A sliding groove is provided at the bottom of the arc frame, a second sliding block is slidably arranged inside the sliding groove, the second sliding block is fixedly connected to the arc plate, a second threaded rod is rotatably connected to the inner side of the sliding groove, the second worm gear is threadedly connected to the second sliding block, a third servo motor is installed on the side of the arc frame, and the output end of the third servo motor extending to the inner side of the sliding groove is fixedly connected to the second threaded rod.

[0018] A plurality of second opening grooves are provided on one side of the arc plate close to the second connecting plate, a spring is installed on the inner side of the second worm gear, the limiting rod is slidably arranged on the inner side of the second opening groove, and the limiting rod and the spring are fixedly connected to limit the second connecting plate, thereby ensuring the stability of the visual inspection camera.

[0019] The present invention has the following beneficial effects:

[0020] 1. In the present invention, by using a multi-stage telescopic mechanism and an arc-shaped moving mechanism in coordination, the position of the visual inspection camera can be adjusted at multiple angles for inspection, which can ensure that the complete image information of the object to be inspected is captured from multiple viewing angles. This all-round, multi-angle inspection method helps to more accurately identify surface defects, dimensional deviations and other problems of the object, thereby improving the precision and accuracy of the inspection.

[0021] 2. In the present invention, when adjusting through the multi-stage telescopic mechanism, the maximum degree of adjustment can be achieved within a limited space, and even higher and lower objects to be inspected can be applied.

[0022] 3. In the present invention, the second connecting plate is limited by a limiting rod, thereby ensuring the stability of the visual inspection camera, helping to maintain the consistency of inspection, and thus improving the overall inspection quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1This is a schematic diagram of the overall structure of a movable visual inspection mechanism proposed by the present invention;

[0024] Figure 2 It is a schematic diagram of a first cross-sectional structure of the multi-stage telescopic mechanism in the present invention;

[0025] Figure 3 It is a second cross-sectional structural schematic diagram of the multi-stage telescopic mechanism in the present invention;

[0026] Figure 4 This is a schematic diagram of the first structure of the arc frame in the present invention;

[0027] Figure 5 It is a schematic diagram of the second structure of the arc frame in the present invention;

[0028] Figure 6 It is a schematic diagram of the cross-sectional structure of the arc plate in the present invention;

[0029] Figure 7 for Figure 1 A schematic diagram of the structure enlargement in the middle;

[0030] Figure 8 for Figure 2 A magnified schematic diagram of the structure at B in the middle;

[0031] Fig. 9 for Figure 3 A magnified schematic diagram of the structure at C in the middle;

[0032] Fig.10 for Figure 4 A magnified schematic diagram of the structure at D in the middle;

[0033] Fig.11 for Figure 4 The enlarged schematic diagram of the structure at E in the middle;

[0034] Fig.12 for Figure 5 A magnified schematic diagram of the structure at F in the middle;

[0035] Fig.13 for Figure 6 Enlarged schematic diagram of the structure at G in the middle.

[0036] In the figure: 1, support frame; 2, first opening slot; 3, first worm gear; 4, round rod; 5, first servo motor; 6, first worm; 7, first connecting plate; 8, first adjustment plate; 9, second adjustment plate; 10, second servo motor; 11, first threaded rod; 12, first rotating rod; 13, second rotating rod; 14, first transmission belt; 15, first gear; 16, first rack; 17, second gear; 18, third adjustment rod; 19, second rack; 20, arc Frame; 21, third rotating rod; 22, fourth rotating rod; 23, second transmission belt; 24, support rod; 25, second worm gear; 26, second servo motor; 27, second worm; 28, arc groove; 29, first sliding block; 30, second connecting plate; 31, visual inspection camera; 32, sliding groove; 33, second sliding block; 34, arc plate; 35, second threaded rod; 36, third servo motor; 37, second opening groove; 38, spring; 39, limit rod. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Embodiment 1

[0039] like Figure 1-Figure 13 As shown, a movable visual inspection mechanism proposed by the present invention comprises a support frame 1, the inner side of the support frame 1 is rotatably connected with a first connecting plate 7, the bottom of the first connecting plate 7 is mounted with an arc frame 20 movably connected thereto, the inner side of the arc frame 20 is movably connected with a visual inspection camera 31, a multi-stage telescopic mechanism for the visual inspection camera 31 is commonly provided between the first connecting plate 7 and the arc frame 20, the multi-stage telescopic mechanism comprises a first adjustment plate 8, a second adjustment plate 9 and a third adjustment rod 18 commonly provided between the first connecting plate 7 and the arc frame 20, the first adjustment plate 8, the second adjustment plate 9 and the third adjustment rod 18 realize the up and down translation of the visual inspection camera 31 by their own up and down telescoping;

[0040] The arc frame 20 is provided with an arc moving mechanism for the visual inspection camera 31, and the arc moving mechanism includes a third rotating rod 21 and a fourth rotating rod 22 which are rotatably connected to the inner side of the arc frame 20, and a second transmission belt 23 is sleeved on the outer sides of the third rotating rod 21 and the fourth rotating rod 22. The rotation of the second transmission belt 23 realizes the arc movement of the visual inspection camera 31 along the arc frame 20. The inner side of the arc frame 20 is movably connected with an arc plate 34, and the side of the arc plate 34 is movably provided with a plurality of limit rods 39 for limiting the visual inspection camera 31.

[0041] A first open slot 2 is provided on the upper part of the support frame 1, and a first worm gear 3 is rotatably connected to the inner side of the first open slot 2, a round rod 4 is installed at the bottom of the first worm gear 3, the round rod 4 is rotatably connected to the support frame 1, and one end of the round rod 4 away from the first worm gear 3 is fixedly connected to the first connecting plate 7, and a first worm 6 is rotatably connected to the inner side of the first open slot 2, a first servo motor 5 is installed on the side of the support frame 1, and the output end of the first servo motor 5 extending to the inner side of the first open slot 2 is fixedly connected to the first worm 6, a first adjusting plate 8 is installed on the end of the first connecting plate 7 away from the round rod 4, and a second adjusting plate 9 is slidably arranged on the inner side of the first adjusting plate 8, a second servo motor 10 is installed on the upper part of the first adjusting plate 8, and a first threaded rod 11 is installed on the output end of the second servo motor 10 extending to the inner side of the first adjusting plate 8, the first threaded rod 11 is rotatably connected to the first adjusting plate 8, and the first threaded rod 11 is threadedly connected to the second adjusting plate 9;

[0042] The inner side of the second adjustment plate 9 is rotatably connected with the first rotating rod 12 and the second rotating rod 13 respectively, and the outer sides of the first rotating rod 12 and the second rotating rod 13 are jointly sleeved with a first transmission belt 14, and the outer side of the first rotating rod 12 is installed with a first gear 15, and the inner side of the first adjustment plate 8 is installed with a first rack 16, and the first gear 15 is meshed with the first rack 16, and the third adjustment rod 18 is slidably arranged on the inner side of the second adjustment plate 9, and the side of the second adjustment plate 9 is installed with a second rack 19, and the outer side of the second rotating rod 13 is installed with a second gear 17, and the second gear 17 is meshed with the second rack 19;

[0043] A second worm gear 25 is installed on the outer side of the third rotating rod 21, and a second worm 27 is rotatably connected to the inner side of the arc frame 20, and the second worm 27 is meshed with the second worm gear 25. A fourth servo motor 26 is installed on the side of the arc frame 20, and the output end of the fourth servo motor 26 extends to the inner side of the arc frame 20 and is fixedly connected to the second worm 27. A plurality of support rods 24 are rotatably connected to the inner side of the arc frame 20, and the plurality of support rods 24 are movably connected to the second transmission belt 23. A second connecting plate 30 is installed on the outer side of the second transmission belt 23, and one end of the second connecting plate 30 away from the second transmission belt 23 is fixedly connected to the visual inspection camera 31. An arc groove 28 is installed on the side of the arc frame 20, and a first sliding block 29 is slidably provided inside the arc groove 28, and the first sliding block 29 is fixedly connected to the second connecting plate 30.

[0044] In this embodiment, when visual inspection is required, the visual inspection camera 31 can be aimed at the object to be inspected, and then the inspection is carried out. If the distance between the visual inspection camera 31 and the object to be inspected needs to be adjusted, the second servo motor 10 is started, and the first threaded rod 11 is driven to rotate by the second servo motor 10. The force generated when the first threaded rod 11 rotates can drive the second adjustment plate 9 to slide, so that the second adjustment plate 9 moves toward the outside of the first adjustment plate 8, and because the first gear 15 is meshed with the first rack 16, when the second adjustment plate 9 moves, the first gear 15 is driven to rotate through the first rack 16, and when the first gear 15 rotates, the first rotating rod 12 is driven to rotate. The first transmission belt 14 is sleeved together with the second rotating rod 13, so when the first rotating rod 12 rotates, the second rotating rod 13 is driven to rotate through the first transmission belt 14, and when the second rotating rod 13 rotates, the second gear 17 is driven to rotate. Since the second gear 17 is meshed with the second rack 19, the third adjusting rod 18 can be driven to move to the outside of the second adjusting plate 9 through the second rack 19 when the second gear 17 rotates, and the second adjusting plate 9 and the third adjusting rod 18 move synchronously, and the arc frame 20 is driven to move at the same time, so as to adjust the distance between the visual inspection camera 31 and the object to be inspected, and through multi-level adjustment, the maximum degree of adjustment can be achieved within a limited space, even if the higher and lower objects to be inspected are also applicable;

[0045] If it is necessary to detect the side of the object to be detected, the first servo motor 5 can be started at this time, and the first servo motor 5 can drive the first worm 6 to rotate. Since the first worm 6 is meshed with the first worm wheel 3, the first worm wheel 3 can be driven to rotate. When the first worm wheel 3 rotates, the first connecting plate 7 can be driven to rotate through the round rod 4, so that the visual inspection camera 31 on the arc frame 20 is driven to rotate through the first adjustment plate 8 and the third adjustment rod 18 until the visual inspection camera 31 is moved to the side that needs to be inspected, and then the fourth servo motor 26 is started, and the second worm 27 is driven to rotate by the fourth servo motor 26. Since the second worm 27 is meshed with the second worm wheel 25, the second worm 27 can be rotated. The third rotating rod 21 is driven to rotate through the second worm gear 25, and the second transmission belt 23 is driven to rotate on the third rotating rod 21, the fourth rotating rod 22 and the support rod 24, thereby driving the second connecting plate 30 to move along the arc groove 28 through the first sliding block 29, and driving the visual inspection camera 31 to move until the visual inspection camera 31 moves to the angle required for inspection on the side of the object to be inspected. In this way, the position of the visual inspection camera 31 is adjusted by multi-angle movement for inspection, which can ensure that the complete image information of the object to be inspected is captured from multiple perspectives. This all-round, multi-angle inspection method helps to more accurately identify defects, dimensional deviations and other problems on the surface of the object, thereby improving the accuracy and reliability of inspection.

[0046] Embodiment 2

[0047] like Figure 1-Figure 13 As shown, based on the first embodiment, a sliding groove 32 is provided at the bottom of the arc frame 20, and a second sliding block 33 is slidingly provided inside the sliding groove 32, and the second sliding block 33 is fixedly connected to the arc plate 34. A second threaded rod 35 is rotatably connected to the inner side of the sliding groove 32, and the second worm gear 25 is threadedly connected to the second sliding block 33. A third servo motor 36 is installed on the side of the arc frame 20, and the output end of the third servo motor 36 extends to the inner side of the sliding groove 32 and is fixedly connected to the second threaded rod 35. A plurality of second opening grooves 37 are provided on one side of the arc plate 34 close to the second connecting plate 30, and a spring 38 is installed on the inner side of the second worm gear 27, and a limit rod 39 is slidably provided on the inner side of the second opening groove 37, and the limit rod 39 and the spring 38 are fixedly connected.

[0048] In this embodiment, before the visual inspection camera 31 performs side angle adjustment, the third servo motor 36 can be started at this time, and the second threaded rod 35 can be driven to rotate by the third servo motor 36. At the same time, the force generated by the rotation of the second threaded rod 35 can drive the second sliding block 33 to move along the sliding groove 32 in the direction away from the second connecting plate 30, and at the same time drive the arc plate 34 to move, so that the limit rod 39 on the arc plate 34 is separated from the second connecting plate 30. When the visual inspection camera 31 is adjusted to the desired position, the third servo motor 36 can be started at this time to drive the second threaded rod 35 to reverse, thereby driving the arc plate 34 to move in the direction close to the second connecting plate 30 until the limit rod 39 is squeezed by the second connecting plate 30 and retracted into the second opening groove 37. At this time, the spring 38 contracts, and at the same time, the limit rod 39 around the second connecting plate 30 that is not squeezed by the second connecting plate 30 limits the second connecting plate 30, thereby ensuring the stability of the visual inspection camera 31, helping to maintain the consistency and accuracy of the inspection, thereby improving the overall inspection quality.

[0049] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A movable visual inspection mechanism, comprising a support frame (1), characterized in that: The inner side of the support frame (1) is rotatably connected to a first connecting plate (7), the bottom of the first connecting plate (7) is movably connected to an arc frame (20), the inner side of the arc frame (20) is movably connected to a visual inspection camera (31), a multi-stage telescopic mechanism for the visual inspection camera (31) is commonly arranged between the first connecting plate (7) and the arc frame (20), the multi-stage telescopic mechanism comprises a first adjustment plate (8), a second adjustment plate (9) and a third adjustment rod (18) which are commonly arranged between the first connecting plate (7) and the arc frame (20), and the first adjustment plate (8), the second adjustment plate (9) and the third adjustment rod (18) realize the up and down translation of the visual inspection camera (31) by their own up and down telescoping; The arc frame (20) is provided with an arc moving mechanism for the visual detection camera (31), the arc moving mechanism comprising a third rotating rod (21) and a fourth rotating rod (22) rotatably connected to the inner side of the arc frame (20), the outer sides of the third rotating rod (21) and the fourth rotating rod (22) are jointly sleeved with a second transmission belt (23), the rotation of the second transmission belt (23) itself enables the visual detection camera (31) to move in an arc along the arc frame (20), the inner side of the arc frame (20) is movably connected with an arc plate (34), and the side of the arc plate (34) is movably provided with a plurality of limit rods (39) for limiting the position of the visual detection camera (31).

2. A movable visual inspection mechanism according to claim 1, characterized in that: A first opening groove (2) is provided on the upper part of the support frame (1), a first worm gear (3) is rotatably connected to the inner side of the first opening groove (2), a round rod (4) is installed at the bottom of the first worm gear (3), the round rod (4) is rotatably connected to the support frame (1), and one end of the round rod (4) away from the first worm gear (3) is fixedly connected to a first connecting plate (7).

3. A movable visual inspection mechanism according to claim 2, characterized in that: A first worm gear (6) is rotatably connected to the inner side of the first opening slot (2), a first servo motor (5) is mounted on the side of the support frame (1), and the output end of the first servo motor (5) extending to the inner side of the first opening slot (2) is fixedly connected to the first worm gear (6).

4. A movable visual inspection mechanism according to claim 1, characterized in that: The first adjustment plate (8) is mounted on an end of the first connecting plate (7) away from the round rod (4); the second adjustment plate (9) is slidably arranged on the inner side of the first adjustment plate (8); a second servo motor (10) is mounted on the upper part of the first adjustment plate (8); a first threaded rod (11) is mounted on the output end of the second servo motor (10) extending to the inner side of the first adjustment plate (8); the first threaded rod (11) is rotationally connected to the first adjustment plate 8, and the first threaded rod 11 is threadedly connected to the second adjustment plate 9.

5. A movable visual inspection mechanism according to claim 4, characterized in that: The inner side of the second adjustment plate (9) is rotatably connected to a first rotating rod (12) and a second rotating rod (13), the outer sides of the first rotating rod (12) and the second rotating rod (13) are jointly sleeved with a first transmission belt (14), the outer side of the first rotating rod (12) is provided with a first gear (15), the inner side of the first adjustment plate (8) is provided with a first rack (16), and the first gear (15) is meshed with the first rack (16).

6. A movable visual inspection mechanism according to claim 5, characterized in that: The third adjustment rod (18) is slidably arranged on the inner side of the second adjustment plate (9); a second rack (19) is installed on the side of the second adjustment plate (9); a second gear (17) is installed on the outer side of the second rotating rod (13); the second gear (17) is meshed with the second rack (19).

7. A movable visual inspection mechanism according to claim 1, characterized in that: A second worm gear (25) is installed on the outer side of the third rotating rod (21); a second worm (27) is rotatably connected to the inner side of the arc frame (20); the second worm (27) and the second worm gear (25) are meshed with each other; a fourth servo motor (26) is installed on the side of the arc frame (20); an output end of the fourth servo motor (26) extends to the inner side of the arc frame (20) and is fixedly connected to the second worm (27); a plurality of support rods (24) are rotatably connected to the inner side of the arc frame (20); the plurality of support rods (24) are movably connected to the second transmission belt (23); a second connecting plate (30) is installed on the outer side of the second transmission belt (23); an end of the second connecting plate (30) away from the second transmission belt (23) is fixedly connected to the visual detection camera (31).

8. A movable visual inspection mechanism according to claim 7, characterized in that: An arc-shaped groove (28) is installed on the side of the arc-shaped frame (20), and a first sliding block (29) is slidably arranged inside the arc-shaped groove (28), and the first sliding block (29) is fixedly connected to the second connecting plate (30).

9. The movable visual inspection mechanism according to claim 7, characterized in that: A sliding groove (32) is provided at the bottom of the arc frame (20), a second sliding block (33) is slidably arranged inside the sliding groove (32), the second sliding block (33) is fixedly connected to the arc plate (34), a second threaded rod (35) is rotatably connected to the inner side of the sliding groove (32), the second worm gear (25) is threadedly connected to the second sliding block (33), a third servo motor (36) is installed on the side of the arc frame (20), and the output end of the third servo motor (36) extending to the inner side of the sliding groove (32) is fixedly connected to the second threaded rod (35).

10. A movable visual inspection mechanism according to claim 9, characterized in that: A plurality of second opening grooves (37) are provided on one side of the arc plate (34) close to the second connecting plate (30); a spring (38) is installed on the inner side of the second worm gear (27); the limiting rod (39) is slidably arranged on the inner side of the second opening groove (37); and the limiting rod (39) and the spring (38) are fixedly connected.

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