Intelligent feeding frame for stamping assembly line

Abstract

The invention relates to an intelligent feeding frame for a stamping assembly line, and relates to the field of feeding equipment, the intelligent feeding frame comprises a conveying frame, one end of the conveying frame is arranged as a working end, a conveying plate is slidably connected to the conveying frame, and a plurality of steel plates are stacked on the conveying plate; the conveying frame is provided with a conveying mechanism used for conveying the conveying plate in the direction close to or away from the working end, the working end is provided with two mounting plates fixedly connected with the conveying frame, the conveying plate is located between the two mounting plates, and the working end is provided with a lifting mechanism used for driving the conveying plate to ascend and descend. The mechanical arm has the effect that the mechanical arm can conveniently take the steel plates with different heights.

Description

Technical Field

[0001] The present application relates to the field of feeding equipment, and in particular to an intelligent feeding rack for a stamping assembly line. Background Art

[0002] At present, in the continuous production process of microwave oven shells, it is necessary to continuously transport individual steel plates to the stamping line for stamping operations. In this process, a stack of steel plates is stacked on one side of the stamping line, and then the robot grabs the individual steel plates one by one and sends them to the stamping line.

[0003] When the manipulator grabs a single steel plate, since several steel plates are stacked, the manipulator usually sucks and grabs a single steel plate from the top of the stack of steel plates in sequence. In this process, the manipulator may drop to the limit position, making it inconvenient to grab the steel plate at the lower part. Summary of the invention

[0004] In order to facilitate the robot to pick up steel plates of different heights, the present application provides an intelligent feeding rack for a stamping line.

[0005] The present application provides an intelligent feeder for a stamping line using the following technical solutions: An intelligent feeding rack for a stamping assembly line comprises a conveying rack, one end of the conveying rack is set as a working end, a conveying plate is slidably connected to the conveying rack, a plurality of steel plates are stacked on the conveying plate, a conveying mechanism for conveying the conveying plate toward or away from the working end is installed on the conveying rack, the working end is provided with two mounting plates fixedly connected to the conveying rack, the conveying plate is located between the two mounting plates, and a lifting mechanism for driving the conveying plate to rise and fall is installed at the working end.

[0006] By adopting the above technical solution, several stacked steel plates are placed on the conveyor plate, and then the conveyor plate and several steel plates on the conveyor plate are conveyed to the working end through the conveying mechanism. The manipulator takes the several steel plates at the working end from top to bottom in sequence. As the top steel plate is taken away by the manipulator, the lifting mechanism is started to drive the conveyor plate to rise, so that the manipulator can always smoothly take away the top steel plate. The intelligent feeding rack can realize automatic control of the conveying process of the steel plate and improve production efficiency. The steel plates on the conveyor plate can be automatically moved to the working end through the conveying mechanism, reducing the need for manual operation and reducing labor intensity.

[0007] Preferably, one of the mounting plates is provided with a long hole, a long rod is slidably connected in the long hole, and a driving member is connected to the long rod for driving the long rod to move towards or away from the other mounting plate.

[0008] By adopting the above technical solution, when the conveying plate drives several stacked steel plates to enter between two mounting plates, the driving member is started, and the driving member drives the long rod to move toward the direction close to the other mounting plate. At this time, it is convenient to push the steel plates on the conveying plate to be flush on both sides.

[0009] Preferably, a mounting groove is provided at the upper end of one of the mounting plates, a magnet block is installed in the mounting groove, one end of the magnet block has a magnetic pole arranged in a direction close to between the two mounting plates and is used to contact multiple steel plates, and the other end of the magnet block has a magnetic pole arranged in a direction away from the two mounting plates.

[0010] By adopting the above technical solution, the multiple steel plates located at the top of the conveying plate all contact the same magnetic pole of the magnet block. Therefore, the multiple steel plates contacting the magnet block can be magnetized by the same magnetic pole, and the multiple steel plates magnetized by the same magnetic pole can repel each other, reducing the occurrence of adjacent steel plates sticking to each other due to the presence of oil on the steel plates, making it easier for the robot to take away one steel plate at a time.

[0011] Preferably, a mounting plate is fixedly connected to the magnet block, and two vertically arranged connecting holes are provided on the mounting plate. A screw is clamped in each of the connecting holes, and the screw is threadedly connected to one of the mounting plates.

[0012] By adopting the above technical solution, the adjustable installation of the magnet block is realized. Specifically, the connection holes on the mounting plate cooperate with the screws so that the magnet block can be firmly fixed on the mounting plate, and the height positions of the magnet block and the mounting plate can be easily adjusted.

[0013] Preferably, an infrared sensor is fixedly connected to the upper end of the mounting plate, the infrared sensor is electrically connected to a controller, and the controller is electrically connected to the lifting mechanism.

[0014] By adopting the above technical solution, the infrared sensor can monitor the position of the topmost steel plate on the conveyor plate in real time and transmit the signal to the controller. When the height of a stack of steel plates is lower than the preset position, the controller will control the lifting mechanism to move the conveyor plate to rise, thereby realizing the function of automatically adjusting the height of the topmost steel plate.

[0015] Preferably, the conveying mechanism includes two conveyor belts, each conveyor belt includes a plurality of rollers arranged along the length direction of the conveying frame, each roller is rotatably connected to the conveying frame, and every two adjacent rollers are connected by a sprocket chain. A driving motor for driving one of the rollers to rotate is fixedly connected to the conveying frame, and two supporting protrusions are provided at the bottom end of the conveying plate, one supporting protrusion corresponds to one conveyor belt, and the supporting protrusion contacts the upper surface of the conveyor belt.

[0016] By adopting the above technical solution, the drive motor is started, and the drive motor drives the corresponding roller to rotate, thereby driving the two conveyor belts to convey the conveying plate. The design of the two supporting protrusions and the two conveyor belts makes it easier for the conveying mechanism to transport the conveying plate more smoothly.

[0017] Preferably, the conveying rack is provided with two force-bearing platforms arranged along the length direction of the conveying rack, and the bottom surface of the conveying plate is provided with two contact platforms, one contact platform corresponds to one force-bearing platform and the contact platform is overlapped on the force-bearing platform, and each of the force-bearing platforms is rollingly fitted with multiple balls.

[0018] By adopting the above technical solution, the stability and smoothness of the conveyor plate during movement can be significantly improved. Specifically, the design of the force-bearing platform and the contact platform enables the bottom of the conveyor plate to have a better support effect, reducing the shaking problem caused by unstable support; and the multiple balls rolling on each force-bearing platform further reduce the friction resistance, improve the transmission efficiency, and ensure the safety and reliability of the steel plate during the entire feeding process.

[0019] Preferably, the lifting mechanism includes a hydraulic cylinder fixedly connected to the bottom wall of the conveying rack, the piston rod of the hydraulic cylinder passes through the conveying rack and is fixedly connected to a storage tank, the upper surface of the storage tank is open, the inner bottom wall of the storage tank is rotatably connected to a threaded rod, the upper end of the threaded rod extends out of the storage tank and is rotatably connected to a receiving rod for pushing the conveying plate, a piston block is vertically slidably connected in the storage tank, the piston block is threadedly connected to the threaded rod, and an oil outlet hole is opened on the upper surface of the piston block.

[0020] By adopting the above technical solution, the hydraulic cylinder is started, and the piston rod of the hydraulic cylinder pushes the storage tank, the threaded rod and the receiving rod to rise and fall, and then pushes the conveying plate to rise and fall, thereby adjusting the height of the topmost steel plate on the conveying plate. When it is necessary to apply lubricating liquid to the piston rod of the hydraulic cylinder, the threaded rod is rotated by a tool, and the rotation of the threaded rod drives the piston block to vertically descend along the storage tank, and the pressure in the storage tank increases at this time. The lubricating liquid in the storage tank can flow out along the oil outlet hole, and the lubricating liquid flowing out of the oil hole is taken out by a tool, and applied to the piston rod of the hydraulic cylinder, so that the hydraulic cylinder can be lifted and lowered more smoothly.

[0021] Preferably, the oil outlet hole includes an opening one, a spherical cavity and an opening two arranged from top to bottom, the diameter of the opening one and the diameter of the spherical cavity are both larger than the diameter of the opening two, a gravity ball is provided in the spherical cavity to block the opening two and the spherical cavity, the diameter of the opening one and the diameter of the spherical cavity are both larger than the diameter of the gravity ball, and a limiting rod is fixedly connected to the connecting point between the opening one and the spherical cavity to limit the gravity ball from entering the opening one.

[0022] By adopting the above technical scheme, the gravity ball can move freely in the spherical cavity. When the pressure in the storage tank increases, the gravity ball will be pushed upward and break away from the second opening. At this time, the lubricating liquid in the storage tank can flow out along the second opening, the spherical cavity and the first opening. When the pressure decreases, the pressure value in the storage tank returns to normal, and the gravity ball will retreat under the action of its own gravity and block the second opening. At this time, the oil outlet is blocked, reducing the occurrence of external dust falling into the storage tank through the oil outlet.

[0023] In summary, the present application includes at least one of the following beneficial technical effects: It is convenient for the manipulator to always smoothly remove the top steel plate; Multiple steel plates magnetized by the same magnetic pole can repel each other, reducing the possibility of adjacent steel plates sticking to each other due to the presence of oil on the steel plates, making it easier for the robot to remove one steel plate at a time; It is convenient to dip the lubricant from the storage tank to lubricate the piston rod of the hydraulic cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the intelligent feeding rack embodied in the embodiment of the present application.

[0025] Figure 2 It is a cross-sectional view of the lifting mechanism according to the embodiment of the present application.

[0026] Figure 3 It is a manifestation Figure 2 Enlarged view of point A in the middle.

[0027] Figure 4 It is a schematic diagram of the magnet block installation structure according to an embodiment of the present application.

[0028] Explanation of the reference numerals: 1. conveying frame; 11. working end; 12. force platform; 13. ball bearing; 2. conveying plate; 21. supporting protrusion; 22. contact platform; 3. conveying mechanism; 31. conveyor belt; 311. roller; 4. mounting plate; 41. mounting groove; 42. long hole; 5. lifting mechanism; 51. hydraulic cylinder; 52. storage tank; 53. threaded rod; 54. receiving rod; 55. receiving block; 56. piston block; 561. slide groove; 562. oil outlet hole; 5621. opening one; 5622. spherical cavity; 5623. opening two; 57. slide rod; 58. limiting rod; 6. magnet block; 61. mounting plate; 611. connecting hole; 62. screw; 7. infrared sensor; 8. long rod; 81. driving cylinder. DETAILED DESCRIPTION

[0029] The following is combined with Figure 1-Figure 4 This application is described in further detail.

[0030] The present application embodiment discloses an intelligent feeding rack for a stamping line. Figure 1 and Figure 2 The intelligent feeding rack includes a conveying rack 1, one end of which is set as a working end 11, and the manipulator is used to take the steel plate from the working end 11. A conveying plate 2 is slidably connected to the conveying rack 1, and a plurality of steel plates are stacked on the conveying plate 2. A conveying mechanism 3 for conveying the conveying plate 2 toward or away from the working end 11 is installed on the conveying rack 1. The working end 11 is provided with two mounting plates 4 fixedly connected to the conveying rack 1, and the conveying plate 2 and the conveying rack 1 are both located between the two mounting plates 4. A lifting mechanism 5 for driving the conveying plate 2 to rise and fall is installed at the working end 11.

[0031] The conveyor plate 2 with several steel plates stacked on it is placed at the end of the conveyor frame 1 away from the working end 11, and then the conveyor mechanism 3 is started, and the conveyor mechanism 3 conveys the conveyor plate 2 and several steel plates to between the two mounting plates 4 at the working end 11. At this time, the manipulator can take the steel plates on the conveyor plate 2 from top to bottom in sequence. As the number of steel plates on the conveyor plate 2 decreases, the lifting mechanism 5 is started, and the lifting mechanism 5 drives the conveyor plate 2 to rise, so that the manipulator can take the steel plates more smoothly. This solution solves the problem that the lower limit of the manipulator's descent may not be able to grasp normally when the manipulator grabs a single steel plate, thereby improving work efficiency and safety.

[0032] Reference Figure 1 and Figure 2 The conveying mechanism 3 includes two conveyor belts 31 arranged along the length direction of the conveyor frame 1, each conveyor belt 31 includes a plurality of rollers 311 arranged along the length direction of the conveyor frame 1, and each roller 311 is rotatably connected to the conveyor frame 1. In the same conveyor belt 31, every two adjacent rollers 311 are connected by a sprocket chain, and a driving motor for driving one of the rollers 311 to rotate is fixedly connected to the conveyor frame 1.

[0033] Two supporting protrusions 21 are provided at the bottom end of the conveying plate 2 . Each supporting protrusion 21 is arranged along the length direction of the conveying frame 1 . One supporting protrusion 21 corresponds to one conveying belt 31 , and the bottom surface of the supporting protrusion 21 contacts the upper surface of the conveying belt 31 .

[0034] When the driving motor is started, the driving motor drives a roller shaft 311 to rotate, thereby driving the two conveyor belts 31 to drive the conveyor plate 2 to move, so that the conveyor plate 2 can move along the conveyor frame 1 to the working end 11. After all the steel plates on the conveyor plate 2 at the working end 11 are taken away, the conveyor plate 2 can be separated from the conveyor frame 1 along the working end 11, and the next conveyor plate 2 stacked with several steel plates is placed at the end of the conveyor frame 1 away from the working end 11 and conveyed to the working end 11, so that the steel plates at the working end 11 can be quickly replenished.

[0035] In addition, the conveyor frame 1 is provided with two force-bearing platforms 12 arranged along the length direction of the conveyor frame 1, and the two conveyor belts 31 are located between the two force-bearing platforms 12. The bottom surface of the conveyor plate 2 is provided with two contact platforms 22, each of which is arranged along the length direction of the conveyor frame 1, one contact platform 22 corresponds to one force-bearing platform 12 and the contact platform 22 is overlapped on the force-bearing platform 12, and the upper surface of each force-bearing platform 12 is embedded with a plurality of balls 13, and each ball 13 is in rolling cooperation with the corresponding contact platform 22. This method further reduces the friction between the conveyor plate 2 and the conveyor frame 1 and improves the transmission efficiency.

[0036] Reference Figure 2 and Figure 3 The lifting mechanism 5 includes a hydraulic cylinder 51 fixedly connected to the bottom wall of the conveying rack 1, the piston rod of the hydraulic cylinder 51 vertically penetrates the conveying rack 1 upward and is fixedly connected to a storage tank 52, the upper surface of the storage tank 52 is open, and the inner bottom wall of the storage tank 52 is rotatably connected to a threaded rod 53, the threaded rod 53 is vertically arranged and the upper end extends out of the storage tank 52 and is rotatably connected to a receiving rod 54, the upper end of the receiving rod 54 is fixedly connected to a receiving block 55, and the receiving block 55 is used to push the conveying plate 2.

[0037] A piston block 56 is vertically slidably connected in the storage tank 52. The piston block 56 is squeezed and clamped in the storage tank 52. A slide groove 561 is provided on the side of the piston block 56. A vertically arranged slide rod 57 is fixedly connected to the inner side wall of the storage tank 52. The slide groove 561 is slidably connected to the slide rod 57. The threaded rod 53 passes through the piston block 56 and the piston block 56 is threadedly connected to the threaded rod 53. An oil outlet hole 562 is provided on the upper surface of the piston block 56.

[0038] The oil outlet hole 562 includes an opening 1 5621, a spherical cavity 5622 and an opening 2 5623 arranged from top to bottom. The diameter of the opening 1 5621 is larger than the diameter of the opening 2 5623, and the diameter of the spherical cavity 5622 is larger than the diameter of the opening 1 5621. A gravity ball is arranged in the spherical cavity 5622 to block the opening 2 5623 and the spherical cavity 5622. The diameters of the opening 1 5621 and the spherical cavity 5622 are both larger than the diameter of the gravity ball, and the diameter of the gravity ball is larger than the diameter of the opening 2 5623. A limiting rod 58 is fixedly connected to the connection between the opening 1 5621 and the spherical cavity 5622 to limit the gravity ball from entering the opening 1 5621.

[0039] When lubricating liquid is needed to be applied to the piston rod of the hydraulic cylinder 51, the threaded rod 53 is rotated with the aid of a tool, and the threaded rod 53 rotates relative to the receiving rod 54 and the storage tank 52, which can drive the piston block 56 to descend, and the pressure in the storage tank 52 increases. The gravity ball is separated from the opening 1, and the oil in the storage tank 52 flows out along the second opening 5623, the spherical cavity 5622 and the first opening 5621. At this time, the lubricating liquid can be dipped with a brush tool and then applied to the piston rod of the hydraulic cylinder 51.

[0040] When the threaded rod 53 does not need to be rotated, in order to limit the receiving rod 54 and the threaded rod 53, the receiving rod 54 and the threaded rod 53 can be locked by means of a pin. The receiving block 55 abuts against the bottom surface of the conveying plate 2, and the threaded rod 53 usually does not rotate relative to the storage tank 52.

[0041] Reference Figure 1 and Figure 4 A mounting groove 41 is provided at the upper end of one of the mounting plates 4, and the mounting groove 41 passes through the corresponding mounting plate 4 horizontally. A magnet block 6 is clamped in the mounting groove 41, and one end of the magnet block 6 has a magnetic pole arranged in a direction close to the direction between the two mounting plates 4 and is used to contact multiple steel plates, and the other end of the magnet block 6 has a magnetic pole arranged in a direction away from the two mounting plates 4.

[0042] The same magnetic pole of the magnet block 6 contacts multiple steel plates at the same time, and the multiple steel plates are magnetized at the same time, and the same end forms the same magnetic pole, so that the adjacent steel plates contacting the magnet block 6 repel each other. The occurrence of adjacent steel plates sticking to each other due to the presence of oil is reduced, making it easier for the robot to pick up a single steel plate.

[0043] One end of the magnet block 6 away from the two mounting plates 4 is fixedly connected with a mounting plate 61, and two vertically arranged connecting holes 611 are provided on the mounting plate 61, and a screw 62 is clamped in each connecting hole 611, and each screw 62 is threadedly connected with the corresponding mounting plate 4, so as to complete the fixing between the mounting plate 61 and the corresponding mounting plate 4. When the height of the magnet block 6 needs to be adjusted, the screw 62 is turned to loosen the screw 62, and then the mounting plate 61 and the magnet block 6 are moved, and the screw 62 moves relative to the connecting hole 611. When the magnet block 6 moves to the required height, each screw 62 is tightened.

[0044] In addition, an infrared sensor 7 is fixedly connected to the upper end of the mounting plate 4, and the infrared sensor 7 is electrically connected to a controller, and the controller is electrically connected to a hydraulic cylinder 51 in the lifting mechanism 5. The infrared sensor 7 is used to detect the height of the steel plate. When the height of the uppermost steel plate is lower than a preset value, the controller will control the lifting mechanism 5 to start, so that the conveying plate 2 is raised, thereby ensuring that the manipulator can always smoothly grab the steel plate.

[0045] A long hole 42 is provided on the mounting plate 4 away from the magnet block 6, and a long rod 8 is slidably connected in the long hole 42. The long hole 42 and the long rod 8 are both vertically arranged. The long rod 8 is connected to a driving member that drives the long rod 8 to move toward or away from another mounting plate 4. The driving member in this embodiment is a driving cylinder 81, and the driving cylinder 81 is fixedly connected to the mounting plate 4 with the long hole 42.

[0046] The driving cylinder 81 is started, and the piston rod of the driving cylinder 81 pushes the long rod 8 to move toward another mounting plate 4, so that the steel plates stacked at the working end 11 can be stacked neatly.

[0047] The implementation principle of the intelligent feeding rack for a stamping assembly line in the embodiment of the present application is as follows: a conveying plate 2 stacked with a plurality of steel plates is placed at an end of the conveying rack 1 away from the working end 11, and then the conveying mechanism 3 is started, and the conveying mechanism 3 transports the conveying plate 2 to between two mounting plates 4. Then the driving cylinder 81 is started, and the driving cylinder 81 pushes the long bar 8 to push a plurality of steel plates toward another mounting plate 4, and then the long bar 8 is controlled to reset. At this time, the manipulator can be started to pick up the steel plate from top to bottom at a time, and during this process, the lifting mechanism 5 intermittently lifts the conveying plate 2.

[0048] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An intelligent feeding rack for a stamping line, characterized in that: The invention comprises a conveying frame (1), one end of the conveying frame (1) being set as a working end (11), a conveying plate (2) being slidably connected to the conveying frame (1), the conveying plate (2) being used to stack a plurality of steel plates, a conveying mechanism (3) being installed on the conveying frame (1) for conveying the conveying plate (2) in a direction close to or away from the working end (11), the working end (11) being provided with two mounting plates (4) fixedly connected to the conveying frame (1), the conveying plate (2) being located between the two mounting plates (4), and a lifting mechanism (5) being installed at the working end (11) for driving the conveying plate (2) to rise and fall.

2. According to claim 1, the intelligent feeder for a stamping line is characterized in that: One of the mounting plates (4) is provided with a long hole (42), a long rod (8) is slidably connected in the long hole (42), and a driving member is connected to the long rod (8) for driving the long rod (8) to move in a direction approaching or away from the other mounting plate (4).

3. The intelligent feeder for a stamping line according to claim 1, characterized in that: A mounting groove (41) is formed at the upper end of one of the mounting plates (4), and a magnet block (6) is mounted in the mounting groove (41). A magnetic pole at one end of the magnet block (6) is arranged in a direction close to between the two mounting plates (4) and is used to contact a plurality of steel plates, and a magnetic pole at the other end of the magnet block (6) is arranged in a direction away from the two mounting plates (4).

4. The intelligent feeder for a stamping line according to claim 3, characterized in that: The magnet block (6) is fixedly connected to a mounting plate (61), the mounting plate (61) being provided with two vertically arranged connecting holes (611), each connecting hole (611) being clamped with a screw (62), the screw (62) being threadedly connected to one of the mounting plates (4).

5. The intelligent feeder for a stamping line according to claim 1, characterized in that: An infrared sensor (7) is fixedly connected to the upper end of the mounting plate (4), the infrared sensor (7) is electrically connected to a controller, and the controller is electrically connected to the lifting mechanism (5).

6. The intelligent feeder for a stamping line according to claim 1, characterized in that: The conveying mechanism (3) comprises two conveyor belts (31), each conveyor belt (31) comprises a plurality of roller shafts (311) arranged along the length direction of the conveyor frame (1), each roller shaft (311) is rotatably connected to the conveyor frame (1), and each two adjacent roller shafts (311) are connected via a sprocket chain. A driving motor for driving one of the roller shafts (311) to rotate is fixedly connected to the conveyor frame (1), and two supporting protrusions (21) are provided at the bottom end of the conveyor plate (2), one supporting protrusion (21) corresponds to one conveyor belt (31), and the supporting protrusion (21) contacts the upper surface of the conveyor belt (31).

7. The intelligent feeder for a stamping line according to claim 6, characterized in that: The conveying frame (1) is provided with two force-bearing platforms (12) arranged along the length direction of the conveying frame (1), and the bottom surface of the conveying plate (2) is provided with two contact platforms (22), one contact platform (22) corresponds to one force-bearing platform (12), and the contact platform (22) is overlapped on the force-bearing platform (12), and each of the force-bearing platforms (12) is rollingly matched with a plurality of balls (13).

8. The intelligent feeder for a stamping line according to claim 6, characterized in that: The lifting mechanism (5) comprises a hydraulic cylinder (51) fixedly connected to the bottom wall of the conveying frame (1); a piston rod of the hydraulic cylinder (51) penetrates the conveying frame (1) and is fixedly connected to a storage tank (52); the upper surface of the storage tank (52) is open; a threaded rod (53) is rotatably connected to the inner bottom wall of the storage tank (52); the upper end of the threaded rod (53) extends out of the storage tank (52) and is rotatably connected to a receiving rod (54) for pushing the conveying plate (2); a piston block (56) is vertically slidably connected in the storage tank (52); the piston block (56) is threadedly connected to the threaded rod (53); and an oil outlet hole (562) is provided on the upper surface of the piston block (56).

9. The intelligent feeder for a stamping line according to claim 8, characterized in that: The oil outlet hole (562) comprises an opening 1 (5621), a spherical cavity (5622) and an opening 2 (5623) arranged from top to bottom; the diameter of the opening 1 (5621) and the diameter of the spherical cavity (5622) are both larger than the diameter of the opening 2 (5623); a gravity ball is arranged in the spherical cavity (5622) to block the opening 2 (5623) and the spherical cavity (5622); the diameter of the opening 1 (5621) and the diameter of the spherical cavity (5622) are both larger than the diameter of the gravity ball; a limiting rod (58) is fixedly connected to the connection between the opening 1 (5621) and the spherical cavity (5622) to limit the gravity ball from entering the opening 1 (5621).

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