Numerical control equipment for bending safe box body

Abstract

The invention discloses numerical control equipment for bending a safe box body, and relates to the technical field of bending equipment. The numerical control equipment for bending the safe box body comprises a workbench, a lower die, an upper die and a ball supporting table, and the ball supporting table comprises a bottom plate and a top plate. According to the numerical control equipment for bending the box body of the safe box, when the steel plate of the box body of the safe box is bent, the bottom of the steel plate can be supported, the situation that the bending angle of the steel plate is inaccurate due to the gravity influence is avoided, the bending quality is guaranteed, meanwhile, a negative pressure state can be formed in the supporting process, and when the steel plate is bent to the needed angle, the bending quality is guaranteed. The electromagnetic valve is opened, the bottom of the steel plate is adsorbed through the adsorption pipe, the adsorption pipe not making contact with the bottom of the steel plate is kept in a closed state, the adsorption effect can be guaranteed, at the moment, the steel plate can be limited, it is avoided that when the steel plate is bent, the steel plate continues to be bent due to inertia, and the influence on the bending angle is avoided; and the bending quality is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bending equipment, in particular to a numerical control equipment for bending processing of a safe box body. BACKGROUND

[0002] The core of the bending processing of the safe box body is the precise bending forming of the metal plate, which relies on the numerical control equipment, mainly the bending machine. The core requirement is to ensure the size accuracy, angle consistency and structural rigidity of the steel plate, especially thick steel plate, after bending, to meet the requirements of the sealing performance and splicing strength of the box body for the anti-theft performance. In addition, a ball bearing support table is usually arranged beside the bending machine, which is mainly used for supporting and conveying the plate to be bent. The friction between the plate and the bracket can be reduced through the rolling of the ball bearing, facilitating the movement and positioning of the plate, thereby reducing the labor intensity of workers and ensuring safe production.

[0003] The plate bending machine for box body production disclosed in Publication No. CN218168289U includes a support frame, a limiting mechanism and a mounting mechanism are arranged on the support frame, the limiting mechanism includes a horizontal sliding rail, a sliding block, a vertical plate, a measuring plate, a sliding sleeve, a sliding plate and a sliding bolt, two horizontal sliding rails are arranged, and the two horizontal sliding rails are respectively mounted on the support frame, a sliding block is slidably connected to each horizontal sliding rail, the limiting mechanism is designed to adjust the position of the sliding plate according to the bending requirement of the plate, so that the plate can be limited at the corresponding position for bending. The position can be conveniently adjusted according to the corresponding scale, thereby improving the convenience of bending. However, the numerical control equipment for bending processing of the existing safe box body is not convenient and fast when in use because the box body steel plate is very thick, has a large mass and a large inertia. When bending, manual support is usually used. Under the action of gravity, the steel plate is prone to deformation, which affects the accuracy of the bending angle. After bending to the required angle, the steel plate is prone to further bending under the action of inertia, which also affects the accuracy of the bending angle, thereby affecting the quality of the bending. SUMMARY

[0004] The present application aims to provide a numerical control equipment for bending processing of a safe box body to solve the problems raised in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a numerical control equipment for bending processing of a safe box body, including a workbench, a lower die, an upper die and a ball bearing support table, the ball bearing support table includes a bottom plate and a top plate, a plurality of lifting rods are inserted into the top of the top plate, the lifting of the lifting rods is driven by a lifting mechanism, a connecting rod is fixedly connected between the lifting rods, a ball bearing is arranged at the upper end of the lifting rod, a suction mechanism for suctioning the bottom of the steel plate is arranged on the side wall of the lifting rod, and a detection mechanism for detecting the position of the upper die is arranged on the side wall of the workbench.

[0006] Preferably, the lifting mechanism comprises two U-shaped plates, and a connecting rod is inserted into the U-shaped plates, a connecting plate is fixedly connected between the two U-shaped plates, and the U-shaped plates are connected with the side wall of the workbench through a rotating mechanism.

[0007] Preferably, the rotating mechanism comprises two installation grooves opened in the side wall of the workbench, a first fixed plate is fixedly connected to the bottom of each installation groove, a motor is fixedly connected to the side wall of the first fixed plate, the output end of the motor is fixedly connected with a rotating block, and the rotating block is fixed to the side wall of the U-shaped plate.

[0008] Preferably, the detection mechanism comprises a mounting bracket fixedly connected to the side wall of the workbench, and a visual sensor is fixedly connected to the side wall of the mounting bracket, and the motor is electrically connected with the visual sensor.

[0009] Preferably, the adsorption mechanism comprises a U-shaped frame, and a hollow roller is rotatably connected to the U-shaped frame through a rotating pipe, the U-shaped frame is connected with the side wall of the lifting rod through a rotating assembly, a plurality of arrayed adsorption pipes are fixedly inserted into the inner wall of the roller, an air extraction mechanism for extracting air in the roller is arranged on the side wall of the bottom plate, and a switching assembly is arranged in each adsorption pipe.

[0010] Preferably, the rotating assembly comprises a second fixed plate fixedly connected to the side wall of the lifting rod, and the U-shaped frame is rotatably connected to the top of the second fixed plate through a rotating shaft.

[0011] Preferably, the air extraction mechanism comprises a fixed cylinder fixedly connected to the side wall of the bottom plate, and a piston is slidably connected in the fixed cylinder through a lifting assembly, an electromagnetic valve is fixedly connected to the side wall of the fixed cylinder, the electromagnetic valve is electrically connected with the visual sensor, a connecting pipe is rotatably connected in each rotating pipe, and the connecting pipe is in communication with the electromagnetic valve through a hose.

[0012] Preferably, the lifting assembly comprises a fixed rod fixedly connected to the top of the piston, a rotating plate is rotatably connected to the upper end of the fixed rod through a first rotating assembly, and the upper end of the rotating plate is rotatably connected to the bottom of the connecting plate through a second rotating assembly.

[0013] Preferably, the first rotating assembly comprises two first fixed blocks fixedly connected to the top of the fixed rod, the lower end of the rotating plate is rotatably connected to the side wall of the first fixed block through a first rotating pin, the bottom of the connecting plate is fixedly connected with two second fixed blocks, and the upper end of the rotating plate is rotatably connected to the side wall of the second fixed block through a second rotating pin.

[0014] Preferably, the switch assembly comprises a first hollow disc fixedly connected in the adsorption pipe, and the bottom of the first hollow disc is fixedly connected with two T-shaped guide rods, the side wall of the T-shaped guide rod is sleeved with a second hollow disc, and the side wall of each T-shaped guide rod is sleeved with a spring, the top of the first hollow disc is inserted with a push rod, and the lower end of the push rod is fixed with the top of the second hollow disc, and the hollow holes on the first hollow disc and the second hollow disc are arranged staggeredly.

[0015] Compared with the prior art, the beneficial effects of the present application are: The numerical control equipment for the bending processing of the safe box body can support the bottom of the steel plate when the steel plate of the safe box body is bent, avoid the inaccuracy of the bending angle caused by the gravity, and ensure the quality of the bending; the negative pressure state can be formed during the supporting process, the electromagnetic valve is opened when the steel plate is bent to the required angle, the bottom of the steel plate is adsorbed by the adsorption pipe, and the adsorption pipe not in contact with the bottom of the steel plate remains closed, so that the adsorption effect can be ensured; at this time, the steel plate can be positioned to avoid the continuous bending of the steel plate due to inertia during the bending, avoid the influence on the bending angle, and ensure the quality of the bending. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the present application; Figure 2 It is a schematic diagram of the overall structure of the present application; Figure 3 It is a schematic diagram of the overall structure of the present application; Figure 4 It is a schematic diagram of the overall structure of the present application; Figure 5 It is a schematic diagram of the overall structure of the present application; Figure 6 It is a schematic diagram of the overall structure of the present application; Figure 7 It is Figure 2 It is a schematic diagram of the overall structure of the present application;

[0017] In the figure: 101, workbench; 102, lower mold; 103, upper mold; 104, ball support table; 105, bottom plate; 106, top plate; 201, U-shaped plate; 202, connecting plate; 301, mounting groove; 302, first fixing plate; 303, motor; 304, rotating block; 401, U-shaped frame; 402, rotating pipe; 403, roller; 404, adsorption pipe; 501, second fixing plate; 502, rotating shaft; 601, second hollow disc; 602, first hollow disc; 603, push rod; 604, T-shaped guide rod; 605, spring; 701, fixed cylinder; 702, electromagnetic valve; 703, hose; 704, connecting pipe; 705, piston; 801, fixed rod; 802, rotating plate; 901, first fixed block; 902, first rotating pin; 903, second fixed block; 904, second rotating pin; 1001, mounting frame; 1002, visual sensor; 11, lifting rod; 12, ball; 13, connecting rod. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0019] Please refer to Figures 1-7 The present application provides a numerical control equipment for bending processing of a safe box body, which comprises a workbench 101, a lower mold 102, an upper mold 103, and a ball support table 104. The ball support table 104 comprises a bottom plate 105 and a top plate 106, both of which are known technologies in the technical field and will not be described here. A plurality of lifting rods 11 are inserted into the top of the top plate 106, and the lifting of the lifting rods 11 is driven by a lifting mechanism. A connecting rod 13 is fixedly connected between the lifting rods 11, and a ball 12 is arranged at the upper end of the lifting rod 11. A suction mechanism for suctioning the bottom of the steel plate is arranged on the side wall of the lifting rod 11, and a detection mechanism for detecting the position of the upper mold 103 is arranged on the side wall of the workbench 101. When the steel plate of the safe box body is bent, the bottom of the steel plate can be supported to avoid inaccurate bending angle caused by gravity, thereby ensuring the quality of the bending. At the same time, a negative pressure state can be formed during the supporting process. When the steel plate is bent to the required angle, the electromagnetic valve 702 is opened to suction the bottom of the steel plate through the adsorption pipe 404. The adsorption pipe 404 not in contact with the bottom of the steel plate remains in a closed state to ensure the adsorption effect. At this time, the steel plate can be positioned to avoid the steel plate from continuing to bend due to inertia during bending, thereby avoiding affecting the bending angle and ensuring the quality of the bending.

[0020] Please refer to Figure 1 , Figure 2 and Figure 7 , the lifting mechanism includes two U-shaped plates 201, and the connecting rod 13 is inserted in the U-shaped plate 201, and the connecting plate 202 is fixedly connected between the two U-shaped plates 201, and the U-shaped plate 201 is connected with the side wall of the workbench 101 through the rotating mechanism, and the U-shaped plate 201 is driven to rotate through the rotating mechanism, so that the connecting rod 13 slides in the U-shaped plate 201, thereby driving the lifting rod 11 to lift.

[0021] Please refer to Figure 1 and Figure 7 , the rotating mechanism includes two installation grooves 301 opened in the side wall of the workbench 101, and the bottom of each installation groove 301 is fixedly connected with a first fixed plate 302, the side wall of the first fixed plate 302 is fixedly connected with a motor 303, the output end of the motor 303 is fixedly connected with a rotating block 304, and the rotating block 304 is fixed with the side wall of the U-shaped plate 201, the motor 303 is started, and the rotation of the motor 303 drives the rotation of the rotating block 304, thereby driving the two U-shaped plates 201 to rotate upward.

[0022] Please refer to Figure 1 , the detection mechanism includes a mounting bracket 1001 fixedly connected with the side wall of the workbench 101, and the side wall of the mounting bracket 1001 is fixedly connected with a visual sensor 1002, the motor 303 is electrically connected with the visual sensor 1002, the position of the upper die 103 is detected by the visual sensor 1002, and the bending angle of the U-shaped plate 201 and the steel plate is ensured to be the same.

[0023] Please refer to Figure 2 , Figure 4 and Figure 5 , the adsorption mechanism includes a U-shaped bracket 401, and the U-shaped bracket 401 is rotatably connected with a hollow roller 403 through a rotating pipe 402, the U-shaped bracket 401 is connected with the side wall of the lifting rod 11 through a rotating assembly, and a plurality of arrayed adsorption pipes 404 are fixedly inserted in the inner wall of the roller 403, the side wall of the bottom plate 105 is provided with an air extraction mechanism for extracting air in the roller 403, and each adsorption pipe 404 is provided with a switch assembly, when the U-shaped plate 201 rotates upward, the connecting plate 202 can be driven to rotate upward synchronously, at this time, the roller 403 is extracted by the air extraction mechanism, and the switch assembly in the adsorption pipe 404 in contact with the bottom of the steel plate is opened, so that the bottom of the steel plate can be adsorbed.

[0024] Please refer to Figure 4The rotating assembly comprises a second fixed plate 501 fixedly connected to the side wall of the lifting rod 11, and the U-shaped frame 401 is rotatably connected to the top of the second fixed plate 501 through a rotating shaft 502, so that the U-shaped frame 401 can be adaptively adjusted in rotation along the rotating shaft 502 when the steel plate moves on the ball 12.

[0025] Please refer to Figure 1 , Figure 3 and Figure 7 , the suction mechanism comprises a fixed cylinder 701 fixedly connected to the side wall of the bottom plate 105, and a piston 705 is slidably connected in the fixed cylinder 701 through a lifting assembly, the side wall of the fixed cylinder 701 is fixedly connected with an electromagnetic valve 702, and the electromagnetic valve 702 is electrically connected with the visual sensor 1002, each rotating pipe 402 is rotatably connected with a connecting pipe 704, and the connecting pipe 704 is in communication with the electromagnetic valve 702 through a hose 703, when bending, when the U-shaped plate 201 rotates upward, the piston 705 can be driven by the lifting assembly to move upward along the fixed cylinder 701, so that negative pressure is generated in the fixed cylinder 701, at the same time, as the bending gradually proceeds, when the ball 12 contacts the bottom of the steel plate, the roller 403 also contacts the bottom of the steel plate, when the steel plate is bent to the required angle, the electromagnetic valve 702 is opened, at this time, the inside of the roller 403 can be suctioned through the hose 703 and the connecting pipe 704, so that negative pressure is generated in the roller 403, so that the adsorption pipe 404 can adsorb the bottom of the steel plate, and the adsorption effect can be ensured, at this time, the steel plate can be positioned to avoid the steel plate from continuing to bend due to inertia when bending, to avoid affecting the bending angle and ensure the quality of bending.

[0026] Please refer to Figure 3 , the lifting assembly comprises a fixed rod 801 fixedly connected to the top of the piston 705, and the upper end of the fixed rod 801 is rotatably connected with a rotating plate 802 through a first rotating assembly, and the upper end of the rotating plate 802 is rotatably connected with the bottom of the connecting plate 202 through a second rotating assembly, when the U-shaped plate 201 rotates upward, the connecting plate 202 can be driven to rotate upward synchronously, at this time, the rotating plate 802 can be rotated, and the piston 705 can be driven to move upward along the fixed cylinder 701 through the fixed rod 801.

[0027] Please refer to Figure 3 , the first rotating assembly comprises two first fixed blocks 901 fixedly connected to the top of the fixed rod 801, and the lower end of the rotating plate 802 is rotatably connected with the side wall of the first fixed block 901 through a first rotating pin 902, the bottom of the connecting plate 202 is fixedly connected with two second fixed blocks 903, and the upper end of the rotating plate 802 is rotatably connected with the side wall of the second fixed block 903 through a second rotating pin 904, to ensure the normal rotation of the rotating plate 802, the connecting plate 202 and the fixed rod 801.

[0028] Please refer to Figures 4-6 The switch assembly comprises a first hollow disc 602 fixedly connected in the adsorption pipe 404, the bottom of the first hollow disc 602 is fixedly connected with two T-shaped guide rods 604, the side wall of the T-shaped guide rod 604 is sleeved with a second hollow disc 601, the side wall of each T-shaped guide rod 604 is sleeved with a spring 605, the top of the first hollow disc 602 is inserted with a push rod 603, and the lower end of the push rod 603 is fixed to the top of the second hollow disc 601, the hollow holes on the first hollow disc 602 and the second hollow disc 601 are arranged staggeredly, when the ball 12 contacts the bottom of the steel plate, the roller 403 also contacts the bottom of the steel plate, and the roller 403 can be pushed to rotate along the rotating pipe 402, when the upper end of the push rod 603 abuts against the bottom of the steel plate, the second hollow disc 601 is pushed to move away from the first hollow disc 602, at the same time, the spring 605 is compressed, at this time, the second hollow disc 601 and the first hollow disc 602 no longer maintain the sealed state, so that the adsorption pipe 404 is opened and contacts the bottom of the steel plate, while the adsorption pipe 404 not contacting the bottom of the steel plate, the second hollow disc 601 and the first hollow disc 602 maintain the sealed state, that is, the adsorption pipe 404 is closed.

[0029] Working principle: in use, when the ball 12 contacts the bottom of the steel plate, the roller 403 also contacts the bottom of the steel plate, and the roller 403 can be pushed to rotate along the rotating pipe 402, when the upper end of the push rod 603 abuts against the bottom of the steel plate, the second hollow disc 601 is pushed to move away from the first hollow disc 602, at the same time, the spring 605 is compressed, at this time, the second hollow disc 601 and the first hollow disc 602 no longer maintain the sealed state, so that the adsorption pipe 404 is opened and contacts the bottom of the steel plate, while the adsorption pipe 404 not contacting the bottom of the steel plate, the second hollow disc 601 and the first hollow disc 602 maintain the sealed state, that is, the adsorption pipe 404 is closed.

[0030] When bending, when the U-shaped plate 201 rotates upward, the connecting plate 202 can be driven to rotate upward synchronously, at this time, the rotating plate 802 can be rotated, and the piston 705 is driven to move upward along the fixed cylinder 701 through the fixed rod 801, so that negative pressure is generated in the fixed cylinder 701, at the same time, as the bending gradually proceeds, when the ball 12 contacts the bottom of the steel plate, the roller 403 also contacts the bottom of the steel plate, and the roller 403 can be pushed to rotate along the rotating pipe 402.

[0031] When the upper end of the pushing rod 603 abuts against the bottom of the steel plate, the second hollow disc 601 can be pushed to move away from the first hollow disc 602, and at the same time, the spring 605 is compressed, at this time, the second hollow disc 601 and the first hollow disc 602 no longer maintain the sealed state, so that the adsorption pipe 404 is opened, and the adsorption pipe 404 is in contact with the bottom of the steel plate, and the adsorption pipe 404 which is not in contact with the bottom of the steel plate, the second hollow disc 601 and the first hollow disc 602 maintain the sealed state, that is, the adsorption pipe 404 is closed.

[0032] When the steel plate is bent to the required angle, the electromagnetic valve 702 is opened, at this time, the air in the roller 403 can be pumped out through the hose 703 and the connecting pipe 704, so that the negative pressure in the roller 403 is generated, so that the adsorption pipe 404 can adsorb the bottom of the steel plate, and the adsorption effect can be ensured, at this time, the steel plate can be positioned to avoid the steel plate from continuing to bend due to inertia when bending, to avoid affecting the bending angle and ensure the bending quality.

[0033] The standard parts used in the application can be purchased from the market, and the special-shaped parts can be ordered according to the description and the drawings, and the specific connection mode of each part adopts the conventional means such as bolts, rivets and welding in the prior art, and the mechanical parts and equipment adopt the conventional type in the prior art, and the circuit connection adopts the conventional connection mode in the prior art, which will not be described in detail here, and the contents not described in detail in the specification belong to the prior art known to those skilled in the art.

[0034] The above describes the application and its embodiments, which are not limited, and the drawings only show one of the embodiments of the application, and the actual structure is not limited thereto. In general, if a person skilled in the art is inspired by it, without departing from the purpose of the application, without creative design, similar structure and embodiments of the technical scheme can be designed, which should belong to the protection scope of the application.

Claims

1. A numerical control device for bending processing of a safe body, comprising a workbench (101), a lower die (102), an upper die (103) and a ball bearing support table (104), the ball bearing support table (104) comprising a bottom plate (105) and a top plate (106), characterized in that: The top of the top plate (106) is provided with a plurality of lifting rods (11), the lifting of the lifting rods (11) is driven by a lifting mechanism, the lifting rods (11) are fixedly connected between the lifting rods (11), and the upper end of the lifting rod (11) is provided with a ball (12); The side wall of the lifting rod (11) is provided with an adsorption mechanism for adsorbing the bottom of the steel plate, and the side wall of the workbench (101) is provided with a detection mechanism for detecting the position of the upper die (103).

2. The numerical control apparatus for bending processing of a safe body according to claim 1, wherein: The lifting mechanism comprises two U-shaped plates (201), and the connecting rod (13) is inserted into the U-shaped plate (201), the two U-shaped plates (201) are fixedly connected between the two U-shaped plates (201), and the U-shaped plate (201) is connected with the side wall of the workbench (101) through a rotating mechanism.

3. The numerical control apparatus for bending processing of a safe body according to claim 2, wherein: The rotating mechanism comprises two mounting grooves (301) formed in the side wall of the workbench (101), and the bottom of each mounting groove (301) is fixedly connected with a first fixed plate (302), the side wall of the first fixed plate (302) is fixedly connected with a motor (303), the output end of the motor (303) is fixedly connected with a rotating block (304), and the rotating block (304) is fixedly connected with the side wall of the U-shaped plate (201).

4. The numerical control apparatus for bending processing of a safe body according to claim 3, wherein: The detection mechanism comprises a mounting frame (1001) fixedly connected to the side wall of the workbench (101), and a visual sensor (1002) fixedly connected to the side wall of the mounting frame (1001), and the motor (303) is electrically connected with the visual sensor (1002).

5. The numerically controlled apparatus for bending processing of a safe case according to claim 2, wherein: The adsorption mechanism comprises a U-shaped frame (401), and the U-shaped frame (401) is rotatably connected with a hollow roller (403) through a rotating pipe (402), the U-shaped frame (401) is connected with the side wall of the lifting rod (11) through a rotating assembly, and a plurality of arrayed adsorption pipes (404) are fixedly inserted into the inner wall of the roller (403), the side wall of the bottom plate (105) is provided with an air extraction mechanism for extracting air in the roller (403), and each adsorption pipe (404) is provided with a switch assembly.

6. The numerically controlled apparatus for bending processing of a safe case according to claim 5, wherein: The rotating assembly comprises a second fixed plate (501) fixedly connected to the side wall of the lifting rod (11), and the U-shaped frame (401) is rotatably connected with the top of the second fixed plate (501) through a rotating shaft (502).

7. The numerically controlled apparatus for bending processing of a safe case according to claim 5, wherein: The air extraction mechanism comprises a fixed cylinder (701) fixedly connected to the side wall of the bottom plate (105), and a piston (705) slidably connected in the fixed cylinder (701) through a lifting assembly, the side wall of the fixed cylinder (701) is fixedly connected with an electromagnetic valve (702), and the electromagnetic valve (702) is electrically connected with the visual sensor (1002), each rotating pipe (402) is rotatably connected with a connecting pipe (704), and the connecting pipe (704) is in communication with the electromagnetic valve (702) through a hose (703).

8. The numerically controlled apparatus for bending processing of a safe case according to claim 7, wherein: The lifting assembly comprises a fixed rod (801) fixedly connected to the top of the piston (705), and the upper end of the fixed rod (801) is rotationally connected with a rotating plate (802) through a first rotating assembly, and the upper end of the rotating plate (802) is rotationally connected with the bottom of the connecting plate (202) through a second rotating assembly.

9. The numerically controlled apparatus for bending processing of a safe case according to claim 8, wherein: The first rotating assembly comprises two first fixed blocks (901) fixedly connected to the top of the fixed rod (801), and the lower end of the rotating plate (802) is rotationally connected with the side wall of the first fixed block (901) through a first rotating pin (902), and the bottom of the connecting plate (202) is fixedly connected with two second fixed blocks (903), and the upper end of the rotating plate (802) is rotationally connected with the side wall of the second fixed block (903) through a second rotating pin (904).

10. The numerical control apparatus for bending processing of a safe body according to claim 5, wherein: The switch assembly comprises a first hollow plate (602) fixedly connected in the adsorption pipe (404), and the bottom of the first hollow plate (602) is fixedly connected with two T-shaped guide rods (604), the side wall of the T-shaped guide rod (604) is sleeved with a second hollow plate (601), and the side wall of each T-shaped guide rod (604) is sleeved with a spring (605), the top of the first hollow plate (602) is inserted with a push rod (603), and the lower end of the push rod (603) is fixed to the top of the second hollow plate (601), and the hollow holes on the first hollow plate (602) and the second hollow plate (601) are arranged staggeredly.

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