Elastic belt tightening device

Abstract

The present invention discloses an elastic belt tightening device, which is characterized in that it comprises: a workbench, a driving component installed at the bottom of the workbench, a transmission assembly installed on the workbench, and the driving component drives the transmission assembly to move in the vertical direction, and a tightening assembly installed on the workbench and adapted to the transmission assembly, and used for tightening the elastic belt into the elastic belt groove of the elastic body; the tightening assembly comprises a support portion arranged on the top of the workbench, a plurality of tightening petals which are annular and slidably arranged on the top surface of the support portion, and a plurality of elastic telescopic rods which are annular and corresponding to the tightening petals on the side walls of the support portion; the transmission assembly comprises a bowl-shaped pushing portion, and all the tightening petals make the elastic belt evenly combined in the single belt groove, thereby preventing the state in which one side of the elastic belt is tight and the other side is loose after being compressed.

Description

Technical Field

[0001] The present invention relates to the technical field of assembly of rotationally stabilized ammunition, and in particular to a device capable of tightening an ammunition belt into an ammunition belt groove of a projectile body. Background Art

[0002] Belt tightening is an important process in the production of ammunition products. When a rifled artillery shell is fired, the belt is embedded in the rifling of the artillery, sealing the gunpowder gas and making the projectile rotate at high speed, ensuring the projectile's flight stability and shooting accuracy.

[0003] The existing belt tightening method is structurally unreasonable and uses a closed inclined cone for circumferential tightening, which has the following problems: 1) The belt and the belt groove are in a state of tightness on one side (upper) and looseness on the other side (lower) along the axis of the projectile, resulting in uneven connection; 2) Before and after the projectile is tightened, one projectile is installed first, then removed after tightening, and then the next projectile is installed, resulting in low efficiency; 3) A large hydraulic press is required as the power source, which takes up a lot of space and is difficult to move.

[0004] In order to solve the above problems, we propose a belt tightening device. Summary of the Invention

[0005] The purpose of the present invention is to provide an elastic belt tightening device. In response to the shortcomings of the prior art, the present invention provides an elastic belt tightening device with the advantages of simplifying the process, improving efficiency, and ensuring uniformity of the combination, thereby solving the problems described in the background art. To achieve the above-mentioned purpose, the present invention provides the following technical solutions: an elastic belt tightening device comprising: a workbench, a driving component mounted at the bottom of the workbench, a transmission assembly mounted on the workbench, wherein the driving component drives the transmission assembly to move in a vertical direction, and a tightening assembly mounted on the workbench and adapted to the transmission assembly, and used to tighten the elastic belt into the elastic belt groove of the projectile body;

[0006] The tightening assembly comprises a support portion mounted on the top of the workbench, a plurality of tightening petals annularly arranged on the top of the support portion, and the tightening petals are slidably connected to the top of the support portion, and a plurality of elastic telescopic rods annularly arranged on the side wall of the support portion, and all the elastic telescopic rods correspond to all the tightening petals one by one;

[0007] The transmission assembly has a bowl-shaped pushing portion. In the tightening state, the pushing portion pushes all the tightening petals to move in a direction close to the axis of the support portion. In the initial state, all the elastic telescopic rods push all the tightening petals to move in a direction away from the axis of the support portion. When all the tightening petals move to the axis of the support portion, the elastic belt is tightened into the elastic belt groove of the elastic body.

[0008] The tightening assembly further comprises a wedge-shaped block mounted on one end of the tightening petal away from the axis of the supporting portion, and the wedge-shaped block is adapted to the inner surface of the pushing portion.

[0009] The top of the support portion is connected with a pressure ring, and the pressure ring is used to limit all the tightening petals on the support portion. A plurality of first limiting grooves adapted to the tightening petals are annularly arranged on the side wall of the pressure ring.

[0010] The limiting assembly comprises a moving plate slidably connected to the supporting portion, a plurality of first limiting grooves arranged along the length direction of the moving plate, and a power source for driving the moving plate to move.

[0011] The limiting component is used to limit the elastic body and is movably arranged at the axial center position of the support part.

[0012] Furthermore, all the tightening petals are provided with arc-shaped pressure plates at one end close to the axis of the support portion, and when all the tightening petals are in the tightening position, all the arc-shaped pressure plates are in a closed loop.

[0013] Furthermore, the number of the tightening petals is six.

[0014] Furthermore, the driving component has a split jack installed on the workbench, a manual hydraulic pump arranged on the split jack, and a pressure gauge arranged on the manual hydraulic pump. The pressure gauge can calculate the thrust output by the split jack through pressure.

[0015] Furthermore, the transmission assembly also has a transmission base plate, the transmission base plate is connected to a transmission shaft via a limit nut, and the transmission base plate is connected to the bottom of the pushing part through a guide rod passing through the top of the workbench.

[0016] Furthermore, the inner surface of the pushing portion is in an inverted cone shape, and its inclination angle is between 17 and 18 degrees.

[0017] Furthermore, a through slot is provided on the support portion, the through slot is slidably connected to the movable plate, and the side wall of the through slot is connected to the limiting block through a first spring, and the side wall of the movable plate is provided with a plurality of positioning holes adapted to the limiting block arranged along its length direction, and the positioning holes correspond one-to-one to the first limiting slot.

[0018] In summary, the present invention has the following beneficial effects:

[0019] This elastic band tightening device drives the transmission assembly upward through the driving component. At this time, the pushing part moves upward, and the inner surface of the pushing part is pressed against the wedge block, so that all the tightening petals move toward the elastic band of the elastic body at the same time, so that the elastic band on the elastic body is squeezed and tightened at the same time. When the tightening petals move to the tightening position, all the tightening petals make the elastic band evenly engaged in the elastic band groove, thereby preventing the elastic band from being tightened on one side and loose on the other side after being compressed.

[0020] By placing multiple elastic bodies into the limiting grooves of the movable plate at the same time, the effect of simultaneously installing multiple elastic bodies is achieved. Then, the driving component is started to make all the tightening petals tighten the multiple elastic bodies in turn. After all the tightening is completed, the multiple elastic bodies on the movable plate are taken out at the same time, thereby achieving the effect of simultaneously taking out and installing multiple elastic bodies, thereby improving efficiency.

[0021] By adopting a split jack and a manual hydraulic pump, the overall volume of the elastic belt tightening device of the present invention is reduced, thereby reducing the space occupied by the elastic belt tightening device of the present invention;

[0022] By cooperating with the limiting block and the positioning hole, the limiting groove can be more accurately positioned at the axial center position of the support portion, and the limiting groove can be more stably limited at the axial center position of the support portion, so that the elastic belt can be more accurately tightened into the elastic belt groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention;

[0024] Figure 2 When the tightening flap of the present invention is in the tightening position Figure 1 Schematic diagram of the structure;

[0025] Figure 3 It is a cross-sectional view of BB of the present invention;

[0026] Figure 4 It is a cross-sectional view of CC of the present invention;

[0027] Figure 5 It is a schematic diagram of the side structure of the present invention;

[0028] Figure 6 This is an enlarged schematic diagram of point A of the present invention;

[0029] Figure 7 DD is a cross-sectional view of the present invention;

[0030] Figure 8 It is a schematic diagram of the three-dimensional structure of the pressure ring of the present invention.

[0031] In the figure: 1. Workbench; 101. Base; 102. Support column; 103. Top plate; 2. Driving component; 201. Split jack; 3. Transmission assembly; 301. Pushing part; 302. Transmission bottom plate; 303. Limit nut; 304. Transmission shaft; 305. Guide rod; 4. Tightening assembly; 401. Support part; 402. Tightening petal; 403. Elastic telescopic rod; 404. Arc pressure plate; 405. Pressure ring; 406. First limiting groove; 407, wedge block; 5, limiting assembly; 501, movable plate; 502, second limiting groove; 503, through groove; 504, first spring; 505, limiting block; 506, positioning hole; 507, power source; 4031, hollow rod; 4032, second spring; 4033, movable rod, 5071, support frame; 5072, stepping motor; 5073, rack; 5074, gear; 3011, movable groove. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0033] See also Figure 1-8 The present invention provides a technical solution: an elastic belt tightening device, comprising:

[0034] The workbench 1 comprises a base 101 mounted on the ground, a top plate 103 connected at four corners of the base 101 via four support columns 102, a drive component 2 mounted on the bottom of the workbench 1, a transmission assembly 3 mounted on the workbench 1, and the drive component 2 drives the transmission assembly 3 to move in a vertical direction, and a tightening assembly 4 mounted on the workbench 1 and adapted to the transmission assembly 3, and used to tighten the elastic belt into the elastic belt slot of the projectile body;

[0035] The tightening assembly 4 comprises a support portion 401 mounted on the top of the workbench 1, the support portion 401 having a support leg fixedly connected to the top of the top plate 103 and a support truncated cone fixedly connected to the support leg, a plurality of tightening petals 402 annularly and slidably arranged on the top surface of the support portion 401, that is, all the tightening petals 402 are annularly arranged on the top of the support truncated cone with the center of the top of the support truncated cone (the axis of the support portion 401), and all the tightening petals 402 are slidably arranged with the top of the support truncated cone, and a plurality of elastic telescopic rods 403 annularly arranged on the side wall of the support portion 401 and corresponding to the tightening petals 402 one by one, that is, all the elastic telescopic rods 403 The ring is arranged on the side wall of the supporting truncated cone, and one end of the elastic telescopic rod 403 is fixedly connected to the side wall of the supporting truncated cone, and the other end of the elastic telescopic rod 403 is fixedly connected to the wedge block 407 at one end of the tightening petal 402. The elastic telescopic rod 403 contains a hollow rod 4031, and one end of the second spring 4032 is connected to the interior of the hollow rod 4031. The other end of the second spring 4032 is connected to one end of the movable rod 4033. When the tightening petal 402 is in the tightening position, the elastic telescopic rod 403 is squeezed. When the tightening petal 402 needs to return to the initial position, the elastic force restored by the elastic telescopic rod 403 causes it to return to the initial position.

[0036] The transmission component 3 has a bowl-shaped pushing portion 301. When in the tightening state, the pushing portion 301 pushes all the tightening petals 402 to move in the direction close to the axis of the support portion 401. When in the initial state, all the elastic telescopic rods 403 push all the tightening petals 402 to move in the direction away from the axis of the support portion. When all the tightening petals 402 move to the axis position of the support portion 401, the elastic belt is tightened into the elastic belt groove of the elastic body, that is, through the cooperation of the pushing portion 301 and the elastic telescopic rod 403, the tightening petals 402 are made to approach or move away from the axis of the telescopic support portion along the axis of the support portion 401. The tightening position (tightening state) and the initial position (initial state) are respectively the position of the tightening petals 4 closest to the axis of the support portion 401 (tightening state of the elastic belt) and the position farthest from the axis of the support portion 401 (initial state of the elastic telescopic rod). When all the tightening petals 402 move to the tightening position, the elastic belt is tightened into the elastic belt groove of the elastic body. When the push part 301 is driven upward by the driving component 2, the inclined surface of the inner wall of the pushing part 301 squeezes the inclined surface of the wedge block 407 at one end of all the tightening petals 402, causing the tightening petals 402 to move in the axial direction. At this time, the elastic telescopic rod 403 is squeezed, so that the other end of the tightening petal 402 squeezes the elastic belt into the elastic belt groove. When the tightening petal 402 moves to the tightening position, the elastic belt is tightened. The driving component 2 drives the pushing part 301 downward, so that the pushing part 301 is away from the wedge block 407 at one end of the tightening petal 402. The inclined surface of the inner wall of the pushing part 301 does not contact the inclined surface of the wedge block 407. At this time, the elastic force restored by the elastic telescopic rod 403 restores the tightening petals 402 to their initial positions. That is to say, the up and down movement of the driving component 2 and the elastic force restored by the elastic telescopic rod 403 enable all the tightening petals 402 to move back and forth between the tightening position and the initial position.

[0037] The limiting assembly 5 is used to limit the elastic body and is movably arranged at the axial center position of the support portion 401.

[0038] Specifically, the tightening assembly 4 further includes a wedge block 407 installed at one end of the tightening petal 402 away from the axis of the support portion 401 , and the inclined surface of the wedge block 407 is adapted to the inner surface of the pushing portion 301 .

[0039] Specifically, all the tightening petals 402 are provided with an arc-shaped pressure plate 404 at one end close to the axis of the support part 401, and when all the tightening petals 402 are in the tightening position, all the arc-shaped pressure plates 404 form a closed loop, and the size of the closed loop is consistent with the size of the elastic belt after it is tightened into the elastic belt groove.

[0040] Specifically, a pressure ring 405 is fixedly connected to the top of the support part 401, and the pressure ring 405 is used to limit all the tightening petals 402 on the support part 401. A number of first limiting grooves 406 that are compatible with the tightening petals 402 are arranged in an annular manner on the side wall of the pressure ring 405. Through the setting of the first limiting grooves 406, when the tightening petals 402 move between the tightening position and the initial position, they are limited to move in the first limiting grooves 406. The size of the first limiting grooves 406 is consistent with the size of the tightening petals 402, and the setting of the pressure ring 405 prevents the tightening petals 402 from moving upward and leaving the support part 401.

[0041] Specifically, there are six tightening petals 402 and six elastic telescopic rods 403 .

[0042] Specifically, the driving component 2 has a split jack 201 installed on the workbench 1, a manual hydraulic pump arranged on the split jack 201, and a pressure gauge arranged on the manual hydraulic pump. The pressure gauge can calculate the thrust output by the split jack 201 through the pressure. The model of the manual hydraulic pump can be CGSB100-1.

[0043] Specifically, the transmission assembly 3 also includes a transmission base plate 302, a transmission shaft 304 connected to the transmission base plate 302 through a limit nut 303, the transmission base plate 302 passes through the top of the workbench 1 and is connected to the bottom of the pushing part 301 through a guide rod 305, the outer surface of the transmission shaft 304 is processed with a thread, and a through hole is processed at the center position of the transmission base plate 302, the transmission shaft 304 passes through the transmission base plate 302 through the center through hole, and the upper and lower surfaces of the transmission base plate 302 are respectively provided with a limit nut 303, which is used to adjust the relative position of the transmission shaft 304 and the transmission base plate 302, and a guide rod 305 is fixedly connected to each of the four corners of the upper surface of the transmission base plate 302, and the four guide rods 305 are symmetrical with each other with the vertical center line of the transmission base plate 302 as the axis of symmetry, and the four guide rods 305 pass through the top plate 103 and are fixedly connected to the bottom of the pushing part 301 at the top.

[0044] Specifically, the inner surface of the pushing portion 301 is in an inverted cone shape, and its inclination angle is between 17 and 18 degrees, and is hard-friction-fitted with the conical inclined surface of the wedge block 407 at one end of the tightening petal 402 .

[0045] The second limiting groove 502 is arranged along the length direction of the movable plate 501, and a power source 507 is provided for driving the movable plate 501 to move. The shape of the second limiting groove 502 is consistent with the shape of one end of the elastic body, and an elastic layer is provided on the inner surface of the second limiting groove 502. After the second limiting groove 502 is provided with the elastic layer, the size of the second limiting groove 502 is slightly smaller than the size of one end of the elastic body, so that after one end of the elastic body is placed into the second limiting groove 502, the elastic layer is squeezed and deformed. At this time, the elastic force restored by the elastic layer makes the elastic body more stably limited in the second limiting groove 502. The power source 507 includes two symmetrically arranged support frames 5071, one of which is provided with a stepping motor 5072. The output end of the stepping motor 5072 is connected to a gear 5074, and the gear 5074 is meshed with a rack 5073. 73 is arranged at the bottom of the movable plate 501 along the length direction thereof, and the side wall of the rack 5073 is slidably connected to the side wall of the support frame 5071, the stepping motor 5072 drives the gear 5074 to rotate, the gear 5074 drives the rack 5073 to move, and the rack 5073 drives the movable plate 501 to move, so that the second limiting groove 502 on the movable plate 501 passes through the axial position of the support part 401 in sequence, and reaches the support part 401 at the second limiting groove 502 with the elastic body to be tightened. When the elastic body of the elastic belt to be tightened is at the axial position of the support part 401, the stepper motor 5072 stops, so that the elastic body of the elastic belt to be tightened is at the axial position of the support part 401, and then the tightening petal 402 is started to move to the tightening position to tighten the elastic on the elastic body. After the tightening is completed, the tightening petal 402 returns to the initial position, and then the stepper motor 5072 is started again to move the elastic body on the next second limiting groove 502 to the axial position of the support part 401, and continue to tighten the elastic body of the next elastic belt to be tightened.

[0046] Specifically, a through slot 503 is provided on the top of the support portion 401, and the through slot 503 passes through both sides of the support portion 401. A movable slot 3011 is provided on both sides of the pushing portion 301 and the pressure ring 405, and the movable slot 3011 is in the same straight line as the through slot 503. The movable plate 501 moves in the movable slot 3011, and the through slot 503 is slidably connected to the movable plate 501. The top of the movable plate 501 is in the same horizontal line as the top of the support portion 401, and the two side walls of the through slot 503 are connected to the limiting block 505 through the first spring 504. The two side walls of the movable plate 501 are arranged along the length direction thereof with a plurality of positioning holes 506 adapted to the limiting block 505, and the positioning holes 506 correspond one to one with the second limiting slot 502. The limiting block 505 is conical in shape, and the positioning holes 506 are for matching with the limiting block 50 5, the cone is adapted to the conical hole of the second limiting groove 502, the positioning holes 506 are arranged on both sides of the axis of the second limiting groove 502, and are symmetrically arranged, the limiting blocks 505 are arranged on both sides of the axis of the support portion 401, and are symmetrically arranged. When the movable plate 501 drives the elastic body in the second limiting groove 502 to move to the axial center position of the support portion 401, the elastic force restored by the first spring 504 causes the limiting block 505 to be inserted into the positioning hole 506, so that the movable plate 501 is limited and immovable. At this time, because the positioning holes 506 are arranged on both sides of the axis of the second limiting groove 502, the limiting blocks 505 are arranged on both sides of the axis of the support portion 401. At this time, after the limiting blocks 505 are inserted into the positioning hole 506, the second limiting groove 502 is positioned, so that the elastic body in the second limiting groove 502 is more accurately limited to the axial center position of the support portion 401.

[0047] The method of using and the working principle of the elastic belt tightening device of the present invention are as follows: first, the movable plate 501 is moved to one side of the workbench 1, and then the elastic belt to be tightened is put on the elastic body. Then, multiple elastic bodies are placed in multiple second limiting grooves 502 respectively. Then, the operator starts the stepper motor 5072, and the stepper motor 5072 drives the gear 5074 to rotate. The gear 5074 drives the rack 5073 to move. The rack 5073 drives the movable plate 501 to move, so that the elastic body in the second limiting groove 502 on the movable plate 501 moves to the axis center position of the support part 401. , then stop the stepper motor 5072, so that the elastic body of the elastic belt to be tightened stops at the axial center position of the support part 401. At this time, the elastic force restored by the first spring 504 causes the limit block 505 to be inserted into the positioning hole 506, so that the movable plate 501 is limited and immovable. Then operate the manual hydraulic pump to make the transmission shaft 304 on the upper part of the piston of the split jack 201 move the pushing part 401 upward. The inner surface of the pushing part 401 directly applies pressure to the tightening petal 402. The other end of the tightening petal 402 gradually squeezes the elastic belt radially, presses the elastic belt into the elastic belt groove, and tightens the elastic belt. After tightening to the right position, the pressure of the manual hydraulic pump is released, and the piston of the split jack 201 moves downward to release the thrust. The tightening petal 402 moves radially away from the axial position of the support part 401 under the action of the elastic force of the elastic telescopic rod 403 to release the elastic body after the tightening elastic belt, completing an operation step of tightening the elastic belt of the elastic body. Then the operator continues to start the stepper motor 5072 to continue to move the movable plate 501, and the movable plate 501 drives the positioning hole 506 to move. At this time, the conical surface of the positioning hole 506 is squeezed by the conical surface of the limit block 505, so that the limit block 505 leaves the positioning hole 506 and squeezes the first spring 504. , and then the moving plate 501 continues to move, so that the next elastic body on the moving plate 501 moves to the axis center of the support part 401, and then the stepping motor 5072 is stopped. At this time, the limit block 505 enters the next positioning hole 506, and the manual hydraulic pump is started to tighten the elastic belt of the next elastic body. Next, the above steps are repeated to tighten the elastic bodies on the moving plate 501 in turn. When all the elastic bodies on the moving plate are tightened, the operator takes out all the elastic bodies on the moving plate, and then places multiple elastic bodies to be tightened into the second limit groove 502, and continues the above steps to continue tightening the elastic belt of the elastic bodies on the moving plate.

[0048] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A belt tightening device, characterized in that: include: A workbench (1), a driving component (2) mounted on the bottom of the workbench (1), a transmission assembly (3) mounted on the workbench (1), wherein the driving component (2) drives the transmission assembly (3) to move in a vertical direction, and a tightening assembly (4) mounted on the workbench (1) and adapted to the transmission assembly (3), and used to tighten an elastic belt into an elastic belt groove of an elastic body; The tightening assembly (4) comprises a support portion (401) mounted on the top of the workbench (1), a plurality of tightening petals (402) arranged in an annular manner on the top of the support portion (401), wherein the tightening petals (402) are slidably connected to the top of the support portion (401), and a plurality of elastic telescopic rods (403) arranged in an annular manner on the side wall of the support portion (401), wherein all the elastic telescopic rods (403) correspond to all the tightening petals (402) in a one-to-one manner; The transmission assembly (3) has a bowl-shaped pushing portion (301), and in a tightening state, the pushing portion (301) pushes all the tightening petals (402) to move in a direction close to the axis of the support portion (401), and in an initial state, all the elastic telescopic rods (403) push all the tightening petals (402) to move in a direction away from the axis of the support portion, and when all the tightening petals (402) move to the axis position of the support portion (401), the elastic belt is tightened into the elastic belt groove of the elastic body; A limiting assembly (5), which is used to limit the position of the elastic body and is movably arranged at the axial center position of the support portion (401); The tightening assembly (4) further comprises a wedge-shaped block (407) mounted on an end of the tightening petal (402) away from the axis of the support portion (401), wherein the wedge-shaped block (407) is adapted to the inner surface of the pushing portion (301); A pressure ring (405) is connected to the top of the support portion (401), and the pressure ring (405) is used to limit all the tightening petals (402) on the support portion (401). A plurality of first limiting grooves (406) adapted to the tightening petals (402) are provided in an annular manner on the side wall of the pressure ring (405); The limiting assembly (5) comprises a movable plate (501) slidably connected to the support portion (401), a plurality of second limiting grooves (502) arranged along the length direction of the movable plate (501), and a power source (507) for driving the movable plate (501) to move.

2. The elastic belt tightening device according to claim 1, characterized in that: All the tightening petals (402) are provided with arc-shaped pressing plates (404) at one end close to the axis of the support portion (401), and when all the tightening petals (402) are in the tightening position, all the arc-shaped pressing plates (404) are in a closed loop.

3. The elastic belt tightening device according to claim 1, characterized in that: The number of the tightening flaps (402) is six.

4. The elastic belt tightening device according to claim 1, characterized in that: The driving component (2) comprises a split jack (201) mounted on the workbench (1), a manual hydraulic pump arranged on the split jack (201), and a pressure gauge arranged on the manual hydraulic pump, wherein the pressure gauge calculates the thrust output by the split jack (201) through pressure.

5. The elastic belt tightening device according to claim 1, characterized in that: The transmission assembly (3) further comprises a transmission base plate (302), a transmission shaft (304) connected to the transmission base plate (302) via a limiting nut (303), and the transmission base plate (302) passes through the top of the workbench (1) and is connected to the bottom of the pushing portion (301) via a guide rod (305).

6. The elastic belt tightening device according to claim 1, characterized in that: The inner surface of the pushing portion (301) is in an inverted cone shape, and its inclination angle is between 17 and 18 degrees.

7. The elastic belt tightening device according to claim 1, characterized in that: A through slot (503) is provided on the support portion (401), the through slot (503) is slidably connected to the movable plate (501), and the side wall of the through slot (503) is connected to a limiting block (505) via a first spring (504), and a plurality of positioning holes (506) adapted to the limiting block (505) are arranged on the side wall of the movable plate (501) along its length direction, and the positioning holes (506) correspond one-to-one to the second limiting slot (502).

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