Mechanism for magnetically layering stacked materials

Abstract

The invention discloses a mechanism for magnetically layering stacked materials, and relates to the technical field of stacking material layering. The device comprises a base, two first rectangular grooves are oppositely formed in the top of the base in the longitudinal direction, supporting rods are arranged in the first rectangular grooves, supporting blocks are slidably arranged on the supporting rods, rectangular frames are fixed to the tops of the supporting blocks, first limiting plates are connected to the sides, close to each other, of the two rectangular frames, and screw rods are arranged on the inner sides of the rectangular frames; a fixing arm is fixed to the face, away from the first limiting plates, of the lifting block, a mounting plate is fixed to the end, away from the lifting block, of the fixing arm, a magnet is mounted on the mounting plate, and an adjusting assembly is arranged between the bottoms of the two supporting blocks, so that the first limiting plates on the two sides and the magnet are conveniently adjusted to move in the horizontal direction; and in combination with threaded fit of the lifting block and the screw rod, the magnet can be conveniently adjusted to move in the vertical direction to adapt to magnetic layering of plates of different sizes, and the magnetic layering effect of the plates is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of stacked material stratification, and in particular relates to a mechanism for magnetically stratifying stacked materials. Background Art

[0002] In the steel sheet application industries such as automobile manufacturing and home appliances, it is difficult to separate the steel plates due to the presence of oil film or vacuum negative pressure between the layers of steel plates after stacking. It is very easy to feed multiple sheets into the mold at the same time during mechanical automatic loading and unloading. In order to avoid multiple sheets being fed into the mold, the sheets need to be layered.

[0003] The traditional layering method is to manually layer the stacked sheets, which is labor-intensive and inefficient, affecting the processing progress. Some magnetic sheeting equipment is used to magnetically layer the stacked sheets, that is, the sheeting poles are fixed on the permanent magnet, and then the entire device is fixed on the table. In actual use, the position of the magnet cannot be adjusted according to the actual size of the sheet, which easily causes different distances between sheets of different sizes and the magnet, resulting in different magnetic forces on sheets of different sizes, affecting the layering effect of the sheets. The scope of application is relatively limited. At the same time, the gaps between the sheets that are layered by the magnetic force are small, and there is a lack of corresponding supporting separation structures. The sheets are easily re-bonded together, resulting in poor layering effect and unfavorable for subsequent clamping of the sheets.

[0004] To solve this problem, we designed a mechanism for magnetically stratifying the piled materials. Summary of the invention

[0005] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0006] The present invention provides a mechanism for magnetically stratifying pile materials, comprising a base and a placement plate arranged on the top of the base, wherein two first rectangular grooves are longitudinally arranged opposite to each other on the top of the base, a support rod is arranged in the first rectangular groove, a support block is slidably arranged on the support rod, a rectangular frame is fixed on the top of the support block, a first limiting plate is arranged on the side where the two rectangular frames are close to each other, two connecting blocks are fixed between the first limiting plate and the rectangular frame, a screw is arranged on the inner side of the rectangular frame, a lifting block is threadedly arranged on the screw, a fixed arm is fixed on the side of the lifting block away from the first limiting plate, a mounting plate is fixed on the end of the fixed arm away from the lifting block, a magnet is mounted on the mounting plate, an adjustment component is arranged between the bottoms of the two support blocks, and a support isolation component is arranged on the side of the lifting block close to the first limiting plate.

[0007] A first servo motor is installed on the top of the rectangular frame, and the output end of the first servo motor is connected to the upper end of the screw rod. Limit rods are arranged on both sides of the screw rod, and the limit rods penetrate the lifting block. The lifting block and the limit rods are slidably matched.

[0008] The support isolation assembly includes a lifting plate, which is fixed on a side of the lifting block away from the fixed arm, a motor is installed on a side of the lifting plate close to the first limit plate, a turntable is connected to the output end of the motor, a cylinder is installed on the side of the turntable away from the motor, and the telescopic end of the cylinder is connected to the isolation block.

[0009] A circular ring is arranged outside the motor, the circular ring is rotatably connected to the lifting plate, a plurality of fixing rods are fixed between the circular ring and the turntable, an avoidance groove penetrates through the first limiting plate, and the cylinder and the isolation block cooperate with the avoidance groove.

[0010] The adjustment assembly includes a vertical plate, two of the vertical plates are relatively fixed at the bottom of the base, a rotating rod is rotatably arranged between the two vertical plates, a winding roller is arranged on the rotating rod, a first spring is sleeved on the outer side of the support rod, and two ends of the first spring are respectively fixedly connected to the support block and the inner wall of the first rectangular groove, a connecting head is fixed at the bottom of the support block, and a steel rope is fixed on the connecting head.

[0011] Two pulley blocks are arranged opposite to each other at the bottom of the base. The end of the steel rope away from the connecting head passes through the pulley block and is fixedly connected to the winding roller. A second servo motor is installed on the lower side of the base through a bracket, and the output end of the second servo motor is connected to the right end of the rotating rod.

[0012] A second rectangular groove is horizontally penetrated through the left side of the base surface, a cross bar is fixed inside the second rectangular groove, the end of the rotating rod away from the second servo motor is connected to a screw rod, a movable block is threadedly arranged on the screw rod, and the cross bar penetrates the movable block.

[0013] The movable block is slidably matched with the cross bar, a support rod is fixed on the top of the movable block, a fixed plate is fixed on the end of the support rod away from the movable block, two piston rods are slidably arranged on the fixed plate, a second limit plate is arranged on the side of the fixed plate away from the support rod, one end of the piston rod is fixedly connected to the second limit plate, and the end of the piston rod away from the second limit plate is fixedly connected to a circular plate, a second spring is fixed between the circular plate and the fixed plate, and the second spring is sleeved on the outside of the piston rod.

[0014] The present invention has the following beneficial effects:

[0015] The present invention facilitates the stacking of plates by placing plates, wherein under the action of the adjusting component, the supporting blocks on both sides are flexibly adjusted to be close to each other, and under the action of the rectangular frame, the first limiting plates on both sides are driven to move closer to the center, so as to achieve the purpose of limiting the two sides of the stacked plates. At the same time, with the movement of the rectangular frame, under the joint action of the lifting block, the fixed arm and the mounting plate, the magnets on both sides are driven to be close to the stacked plates, so as to adapt to the magnetic stratification of plates of different sizes, without the need for manual stratification of the plates, thus saving manpower and solving the problem that the existing magnetic sheeting equipment cannot adjust the position of the magnet according to the actual size of the plates during actual use, which easily causes different distances between the plates of different sizes and the magnet, resulting in different magnetic forces on the plates of different sizes, affecting the stratification effect of the plates, and having a relatively limited scope of application.

[0016] Under the action of the supporting and isolating component, it is convenient to isolate and support the two adjacent sheets after magnetic stratification, so that the two adjacent sheets are separated, which is convenient for the subsequent clamping of the robot. This solves the problem in the prior art that the sheets are stratified by the magnetic force, the gap between the sheets is small, and there is a lack of corresponding supporting and separating structures, which makes it easy for the sheets to be re-attached together, resulting in poor stratification effect and unfavorable for subsequent clamping of the sheets.

[0017] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 A top view of the present invention;

[0021] Figure 3 for Figure 2 Structural diagram of the middle section AA;

[0022] Figure 4 for Figure 3 Schematic diagram of the structure of the middle section BB;

[0023] Figure 5 for Figure 3 Schematic diagram of the enlarged structure at C in the middle;

[0024] Figure 6 for Figure 4 Schematic diagram of the enlarged structure at D in the middle;

[0025] Figure 7 for Figure 4 Schematic diagram of the enlarged structure at E in the middle;

[0026] Figure 8 It is a structural schematic diagram of the present invention;

[0027] Fig. 9 for Figure 8 The enlarged structural diagram at F in the middle;

[0028] Fig.10 for Figure 8 Schematic diagram of the enlarged structure at G in the middle;

[0029] Fig.11 It is a schematic diagram of the structure of the support isolation assembly in the present invention.

[0030] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0031] 1. Base; 2. Placement plate; 3. First rectangular groove; 4. Support rod; 5. Support block; 6. Rectangular frame; 7. Connecting block; 8. First limit plate; 9. Avoidance groove; 10. Magnet; 11. Screw; 12. Lifting block; 13. Fixed arm; 14. Mounting plate; 15. First servo motor; 16. Limit rod; 17. First spring; 18. Connector; 19. Lifting plate; 20. Ring; 21. Motor ; 22. turntable; 23. fixed rod; 24. cylinder; 25. isolation block; 26. vertical plate; 27. rotating rod; 28. winding roller; 29. ​​steel rope; 30. pulley block; 31. second servo motor; 32. second rectangular groove; 33. cross bar; 34. movable block; 35. screw rod; 36. support rod; 37. fixed plate; 38. piston rod; 39. second limit plate; 40. second spring; 41. round plate. DETAILED DESCRIPTION

[0032] 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.

[0033] In the description of the present invention, it should be understood that the terms "upper", "middle", "outer", "inner" and the like indicating directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0034] See also Figure 1-Figure 11 As shown, the present invention is a mechanism for magnetically stratifying pile materials, comprising a base 1 and a placement plate 2 arranged on the top of the base 1, two first rectangular grooves 3 are longitudinally arranged on the top of the base 1, a support rod 4 is arranged in the first rectangular groove 3, a support block 5 is slidably arranged on the support rod 4, a rectangular frame 6 is fixed on the top of the support block 5, a first limiting plate 8 is arranged on the side where the two rectangular frames 6 are close to each other, two connecting blocks 7 are fixed between the first limiting plate 8 and the rectangular frame 6, a screw rod 11 is arranged on the inner side of the rectangular frame 6, a lifting block 12 is threadedly arranged on the screw rod 11, a fixed arm 13 is fixed to a side of the lifting block 12 away from the first limiting plate 8, a mounting plate 14 is fixed to the end of the fixed arm 13 away from the lifting block 12, a magnet 10 is installed on the mounting plate 14, an adjustment component is arranged between the bottoms of the two support blocks 5, and a support isolation component is arranged on the side of the lifting block 12 close to the first limiting plate 8.

[0035] The stacking of the plates is facilitated by placing the plate 2, wherein under the action of the adjusting component, the support blocks 5 on both sides can be flexibly adjusted to be close to each other, and under the action of the rectangular frame 6, the first limiting plates 8 on both sides are driven to be close to the center, so as to achieve the purpose of limiting the two sides of the stacked plates. At the same time, with the movement of the rectangular frame 6, under the joint action of the lifting block 12, the fixed arm 13 and the mounting plate 14, the magnets 10 on both sides are driven to be close to the stacked plates, so as to adapt to the magnetic stratification of plates of different sizes, without the need for manual stratification of the plates, thus saving manpower and solving the problem of existing magnetic sheeting equipment in actual use. In the process, the position of the magnet cannot be adjusted according to the actual size of the sheet, which easily causes different distances between sheets of different sizes and the magnet, resulting in different magnetic forces on sheets of different sizes, affecting the stratification effect of the sheet, and has the disadvantage of limited scope of application. Under the action of the supporting isolation component, it is convenient to isolate and support the two adjacent sheets after magnetic stratification, which solves the problem that the sheets are stratified by the magnetic force in the prior art, the gap between the sheets is small, and there is a lack of corresponding supporting separation structure, which makes it easy for the sheets to be re-attached together, resulting in poor stratification effect and unfavorable for subsequent sheet clamping.

[0036] A first servo motor 15 is installed on the top of the rectangular frame 6. The output end of the first servo motor 15 is connected to the upper end of the screw 11. Limit rods 16 are arranged on both sides of the screw 11. The limit rods 16 penetrate the lifting block 12. The lifting block 12 and the limit rods 16 are slidably matched.

[0037] The supporting isolation assembly includes a lifting plate 19, which is fixed on the side of the lifting block 12 away from the fixed arm 13. A motor 21 is installed on the side of the lifting plate 19 close to the first limit plate 8. The output end of the motor 21 is connected to a turntable 22. A cylinder 24 is installed on the side of the turntable 22 away from the motor 21, and the telescopic end of the cylinder 24 is connected to the isolation block 25.

[0038] A circular ring 20 is arranged outside the motor 21, and the circular ring 20 is rotatably connected to the lifting plate 19. A plurality of fixing rods 23 are fixed between the circular ring 20 and the turntable 22. An avoidance groove 9 runs through the first limit plate 8, and the cylinder 24 and the isolation block 25 cooperate with the avoidance groove 9.

[0039] The adjustment component includes a vertical plate 26, and the two vertical plates 26 are relatively fixed at the bottom of the base 1. A rotating rod 27 is rotatably arranged between the two vertical plates 26, and a winding roller 28 is arranged on the rotating rod 27. A first spring 17 is sleeved on the outer side of the support rod 4, and the two ends of the first spring 17 are respectively fixedly connected to the support block 5 and the inner wall of the first rectangular groove 3. A connecting head 18 is fixed at the bottom of the support block 5, and a steel rope 29 is fixed on the connecting head 18.

[0040] Two pulley blocks 30 are relatively arranged at the bottom of the base 1. The end of the steel rope 29 away from the connecting head 18 passes through the pulley block 30 and is fixedly connected to the winding roller 28. A second servo motor 31 is installed on the lower side of the base 1 through a bracket. The output end of the second servo motor 31 is connected to the right end of the rotating rod 27.

[0041] A second rectangular groove 32 is horizontally penetrated on the left side of the surface of the base 1, a cross bar 33 is fixed inside the second rectangular groove 32, and a screw rod 35 is connected to the end of the rotating rod 27 away from the second servo motor 31. A movable block 34 is threaded on the screw rod 35, and the cross bar 33 penetrates the movable block 34.

[0042] The movable block 34 is slidably matched with the cross bar 33, a support rod 36 is fixed on the top of the movable block 34, a fixed plate 37 is fixed on the end of the support rod 36 away from the movable block 34, two piston rods 38 are slidably arranged on the fixed plate 37, a second limit plate 39 is arranged on the side of the fixed plate 37 away from the support rod 36, one end of the piston rod 38 is fixedly connected to the second limit plate 39, and the end of the piston rod 38 away from the second limit plate 39 is fixedly connected to a circular plate 41, a second spring 40 is fixed between the circular plate 41 and the fixed plate 37, and the second spring 40 is sleeved on the outside of the piston rod 38.

[0043] Example:

[0044] During use, the sheet materials are first stacked on the placement plate 2. After the sheet materials are stacked, the second servo motor 31 is started, and the second servo motor 31 drives the rotating rod 27 to rotate, which drives the winding roller 28 to rotate. Under the action of the pulley group 30, the steel ropes 29 on both sides are wound up. Through the winding of the steel ropes 29, combined with the connecting head 18, and the sliding cooperation between the support block 5 and the support rod 4, the support block 5 is driven to move toward the center along the direction of the support rod 4, and the first spring 17 is squeezed;

[0045] As the support blocks 5 on both sides approach each other, the rectangular frame 6 is driven to move synchronously, and combined with the connecting block 7, the first limiting plate 8 is driven to move closer to the center until the first limiting plate 8 contacts the side of the stacked sheet, thereby achieving the purpose of limiting the front and rear sides of the sheet;

[0046] During the movement of the rectangular frame 6, under the action of the lifting block 12, the fixed arm 13 and the mounting plate 14, the magnet 10 is driven close to the sheet material, so as to achieve the purpose of magnetic stratification of the sheet material, and avoid the magnet 10 being far away from the sheet material, which affects the effect of magnetic stratification of the sheet material, and solves the problem that the existing magnetic sheet separation equipment cannot adjust the position of the magnet according to the actual size of the sheet material during actual use, which easily causes different distances between sheets of different sizes and the magnet, resulting in different sizes of magnetic forces on sheets of different sizes, affecting the stratification effect of the sheet material, and having a relatively limited scope of application;

[0047] The second servo motor 31 drives the rotating rod 27 to rotate, which drives the screw rod 35 to rotate synchronously. Under the threaded cooperation between the movable block 34 and the screw rod 35, combined with the sliding cooperation between the movable block 34 and the cross bar 33, the movable block 34 is driven to move in the direction close to the winding roller 28, and combined with the support rod 36, the fixed plate 37 is driven to move in the direction close to the sheet material until the second limit plate 39 contacts the left end surface of the sheet material. As the movable block 34 continues to move, under the active cooperation between the piston rod 38 and the fixed plate 37, combined with the elastic action of the second spring 40, the second limit plate 39 is used to limit the left end of the sheet material.

[0048] Through the action of the magnet 10, a gap is generated between the uppermost sheet and the adjacent sheets. When the manipulator approaches the sheets and needs to clamp the uppermost sheet, the cylinder 24 is started, and the cylinder 24 extends to drive the isolation block 25 to be inserted into the gap between the uppermost sheet and the adjacent sheets. Then the motor 21 is started, and under the action of the ring 20 and the fixing rod 23, the turntable 22 is mobilized to rotate stably, thereby driving the cylinder 24 and the isolation block 25 inserted between the two adjacent sheets to rotate synchronously. Through the rotation of the isolation block 25, the uppermost sheet is lifted up, which is convenient for the manipulator to clamp the uppermost sheet, solving the problem in the prior art that the sheets are layered under the action of magnetic force, the gap between the sheets is small, and there is a lack of corresponding supporting and separating structures, which makes it easy for the sheets to be re-attached together, resulting in poor layering effect and inconvenience for subsequent sheet clamping.

[0049] After the top layer of sheet material is clamped, the first servo motor 15 is started, and the screw 11 is driven to rotate by the first servo motor 15. Under the threaded cooperation between the lifting block 12 and the screw 11, combined with the sliding cooperation between the lifting block 12 and the limit rod 16, the lifting block 12 is adjusted to move downward stably. Combined with the fixed arm 13 and the mounting plate 14, the magnet 10 is driven to move downward synchronously. At the same time, in the process of the lifting block 12 moving downward, the supporting isolation component is driven to move downward synchronously, so as to facilitate the magnetic stratification of the lower layer of sheet material and facilitate the subsequent clamping of the sheet material.

[0050] It should be further explained that the installation structure, connection method or setting method of each component in the present invention are all common mechanical methods, and any method that can achieve its beneficial effects can be implemented. At the same time, the first servo motor 15, the motor 21, the cylinder 24 and the second servo motor 31 in the present invention are all purchased on the market, and those skilled in the art can install and use them according to the requirements;

[0051] The steel ropes 29 on both sides are staggered so that when the winding roller 28 rotates, the steel ropes 29 on both sides can be stably wound up at the same time.

[0052] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0053] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A mechanism for magnetically stratifying a pile of materials, comprising a base (1) and a placement plate (2) arranged on the top of the base (1), characterized in that: The top of the base (1) is provided with two first rectangular grooves (3) facing each other in the longitudinal direction, a support rod (4) is arranged in the first rectangular groove (3), a support block (5) is slidably arranged on the support rod (4), a rectangular frame (6) is fixed on the top of the support block (5), a first limiting plate (8) is arranged on the side where the two rectangular frames (6) are close to each other, two connecting blocks (7) are fixed between the first limiting plate (8) and the rectangular frame (6), and a screw is arranged inside the rectangular frame (6). (11), a lifting block (12) is threadedly arranged on the screw rod (11), a fixed arm (13) is fixed on a side of the lifting block (12) away from the first limit plate (8), a mounting plate (14) is fixed on an end of the fixed arm (13) away from the lifting block (12), a magnet (10) is mounted on the mounting plate (14), an adjustment component is arranged between the bottoms of the two support blocks (5), and a support isolation component is arranged on a side of the lifting block (12) close to the first limit plate (8).

2. The mechanism for magnetically stratifying piled materials according to claim 1, characterized in that: A first servo motor (15) is installed on the top of the rectangular frame (6); an output end of the first servo motor (15) is connected to the upper end of the screw rod (11); limiting rods (16) are arranged on both sides of the screw rod (11); the limiting rods (16) penetrate the lifting block (12); and the lifting block (12) and the limiting rods (16) are slidably matched.

3. The mechanism for magnetically stratifying piled materials according to claim 2, characterized in that: The support isolation assembly comprises a lifting plate (19), the lifting plate (19) being fixed on a side of the lifting block (12) away from the fixed arm (13), a motor (21) being installed on a side of the lifting plate (19) close to the first limit plate (8), an output end of the motor (21) being connected to a turntable (22), a cylinder (24) being installed on a side of the turntable (22) away from the motor (21), and a telescopic end of the cylinder (24) being connected to an isolation block (25).

4. The mechanism for magnetically stratifying piled materials according to claim 3, characterized in that: A circular ring (20) is arranged outside the motor (21), and the circular ring (20) is rotatably connected to the lifting plate (19). A plurality of fixing rods (23) are fixed between the circular ring (20) and the rotating disk (22). An avoidance groove (9) runs through the first limiting plate (8), and the cylinder (24) and the isolation block (25) both cooperate with the avoidance groove (9).

5. The mechanism for magnetically stratifying piled materials according to claim 4, characterized in that: The adjustment assembly comprises a vertical plate (26), two vertical plates (26) are relatively fixed at the bottom of the base (1), a rotating rod (27) is rotatably arranged between the two vertical plates (26), a winding roller (28) is arranged on the rotating rod (27), a first spring (17) is sleeved on the outer side of the support rod (4), and two ends of the first spring (17) are respectively fixedly connected to the support block (5) and the inner wall of the first rectangular groove (3), a connecting head (18) is fixed at the bottom of the support block (5), and a steel rope (29) is fixed on the connecting head (18).

6. The mechanism for magnetically stratifying piled materials according to claim 5, characterized in that: Two pulley blocks (30) are arranged opposite to each other at the bottom of the base (1); one end of the steel rope (29) away from the connector (18) passes through the pulley block (30) and is fixedly connected to the winding roller (28); a second servo motor (31) is installed on the lower side of the base (1) through a bracket; an output end of the second servo motor (31) is connected to the right end of the rotating rod (27).

7. The mechanism for magnetically stratifying piled materials according to claim 6, characterized in that: A second rectangular groove (32) is passed through the left side of the surface of the base (1) in the transverse direction, a cross bar (33) is fixed inside the second rectangular groove (32), one end of the rotating rod (27) away from the second servo motor (31) is connected to a screw rod (35), a movable block (34) is threadedly arranged on the screw rod (35), and the cross bar (33) passes through the movable block (34).

8. The mechanism for magnetically stratifying piled materials according to claim 7, characterized in that: The movable block (34) is slidably matched with the cross bar (33); a support rod (36) is fixed on the top of the movable block (34); a fixed plate (37) is fixed on one end of the support rod (36) away from the movable block (34); two piston rods (38) are slidably arranged on the fixed plate (37); a second limit plate (39) is arranged on one side of the fixed plate (37) away from the support rod (36); one end of the piston rod (38) is fixedly connected to the second limit plate (39); one end of the piston rod (38) is fixedly connected to the second limit plate (39); a circular plate (41) is fixedly connected to one end of the piston rod (38) away from the second limit plate (39); a second spring (40) is fixed between the circular plate (41) and the fixed plate (37); and the second spring (40) is sleeved on the outside of the piston rod (38).

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