A production device for preventing cataract lenses and a lens for preventing cataract presbyopia

Abstract

The present invention relates to the technical field of lens production, and specifically to a production device for preventing cataract lenses and a lens for preventing cataract presbyopia, comprising an injection molding barrel, a nozzle and a telescopic protective tube are installed at one end of the injection molding barrel, an extrusion plate is installed at one end of the telescopic protective tube, a rotating gear is rotatably connected to the inner cavity of the extrusion plate, a first rack and a second rack are rotatably connected to the top and bottom of the rotating gear respectively, a sealing plate is fixedly connected to the first rack and the second rack, a spiral groove is opened on the inner wall of the rotating gear, an extrusion ring is slidably connected to the inner wall of the rotating gear, and a limiting column that cooperates with the spiral groove is arranged on the outer wall of the extrusion ring. The present invention arranges a telescopic protective sleeve outside the nozzle, and arranges a sealing member composed of a rotating gear, an extrusion ring and a sealing plate at the end of the protective sleeve, so that the nozzle can be wrapped inside, thereby protecting the nozzle and preventing impurities such as dust from entering the injection molding barrel from the opening of the nozzle or adhering to the outside of the nozzle.

Description

Technical Field

[0001] The invention relates to the technical field of lens processing, in particular to a production device for preventing cataracts and a lens for preventing cataracts and presbyopia. Background Art

[0002] When producing lenses, an injection molding machine is required for injection molding. However, when the existing injection molding machine is not working, its nozzle is partially exposed to the air, and dust and other particles in the air may enter the injection molding barrel through the opening of the nozzle or adhere to the outside of the nozzle, which results in the need to clean the injection molding nozzle before each processing, which affects the processing efficiency. To this end, the present invention has developed a production device for preventing cataract lenses and a lens for preventing cataract presbyopia to solve the above problems. Summary of the invention

[0003] The purpose of the present invention is to provide a production device for preventing cataract lenses and lenses for preventing cataract presbyopia, which are used to solve the technical problems raised by the above-mentioned background technology.

[0004] To achieve the above object, the present invention provides the following first technical solution:

[0005] A production device for preventing cataract lenses, comprising an injection molding machine, the injection molding machine comprising a mold mechanism and an injection molding barrel, a nozzle and a telescopic protective tube are installed at one end of the injection molding barrel, the telescopic protective tube is arranged outside the nozzle, an extrusion plate with a hollow interior and first through holes at both ends is installed at one end of the telescopic protective tube, a rotating gear is rotatably connected to a side of the extrusion plate cavity away from the injection molding barrel, and a second through hole that cooperates with the nozzle is opened in the middle of the rotating gear, a first rack and a second rack are rotatably connected to the top and bottom of the rotating gear respectively, and The first rack and the second rack are respectively slidably connected to the top and bottom of the inner cavity of the extrusion plate, and the first rack and the second rack are respectively fixedly connected with sealing plates for sealing the first through hole that cooperate with each other on one side close to the injection molding barrel, a spiral groove is provided on the inner wall of the rotating gear, and an extrusion ring with two ends passing through is slidably connected to the inner wall of the rotating gear, and a limiting column that cooperates with the spiral groove is provided on the outer wall of the extrusion ring, and a limiting ring is provided at the end of the extrusion ring away from the extrusion plate, and a first spring is sleeved on the outer wall of the extrusion ring, and the first spring is located between the limiting ring and the extrusion plate.

[0006] Preferably, T-shaped limit strips are provided at the top of the first rack and the bottom of the second rack, and limit slide grooves that cooperate with the T-shaped limit strips are provided at the top and bottom of the inner cavity of the extrusion plate.

[0007] Preferably, the inner cavity of the sealing plate is a hollow structure, and a semicircular plate for sealing the nozzle is provided on one side of the sealing plate close to the nozzle, and a connecting rod is fixedly connected to the side of the semicircular plate away from the nozzle, one end of the connecting rod is inserted into the inner cavity of the sealing plate and is provided with an extrusion block, and the connecting rod is slidably connected to the sealing plate, and abutment rods are staggeredly provided on the side of the two sealing plates close to each other, and an abutment block that cooperates with the extrusion block is provided at the free end of the abutment rod, and an insertion groove that cooperates with the abutment block is provided on the side wall of the sealing plate, and the side of the extrusion block and the abutment block close to each other is provided with mutually matching inclined surfaces, and a second spring is sleeved on the outer wall of the connecting rod, and the second spring is located inside the sealing plate.

[0008] Preferably, the sealing plate is recessed inwardly to form an embedding groove adapted to the semicircular plate.

[0009] Preferably, the two semicircular plates are provided with mutually matching limiting grooves and limiting strips on one side close to each other.

[0010] Preferably, the telescopic protective tube comprises an outer tube and an inner tube which are slidably connected, the outer tube is connected to the injection molding barrel, the inner tube is connected to the extrusion plate, and limit slots are symmetrically provided on both sides of the outer walls of the outer tube and the inner tube, the extrusion plate is slidably connected with a limit piece which cooperates with the two limit slots, and when the two sealing plates slide in a direction away from each other, the two sealing plates respectively push the two limit pieces out of the limit slots, and the outer walls of the outer tube and the inner tube are both covered with electric heating sleeves.

[0011] Preferably, a third spring is sleeved on the outer wall of the telescopic protection tube.

[0012] Preferably, the limiting member includes a fixed shaft fixed to the inner wall of the extrusion plate, the fixed shaft is slidably connected to a limiting rod, one end of the limiting rod passes through the inner cavity of the extrusion plate and is provided with limiting teeth that cooperate with two limiting slots, and a fourth spring is sleeved on the outer wall of the fixed shaft, and the fourth spring is located between the limiting rod and the inner wall of the extrusion plate.

[0013] At the same time, the second technical solution provided by the present invention is:

[0014] A cataract-prevention presbyopia lens, wherein the cataract-presbyopia lens is obtained by injection molding a molten mixed raw material using a production device and then grinding and polishing it;

[0015] The weight percentages of the various raw material components of the cataract presbyopia lens are as follows:

[0016] Thermosetting resin 93%-99%;

[0017] Fluorescent brightener 0.001%-1.00%;

[0018] HS-16# powder 0.001%-1.00%;

[0019] Initiator 0.20%-0.50%;

[0020] UV powder 0.10%-2.00%;

[0021] Blue agent 0.10%-1.00%;

[0022] Red agent 0.15%-1.5%.

[0023] Preferably, the fluorescent brightener is 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene or 2,2′-(4,4′-distyryl)bisbenzoxazole, and the thermosetting resin is NK-55C or TS-46 or CW-DQ55 or CR-39.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention arranges a retractable protective sleeve outside the nozzle, and arranges a sealing member composed of a rotating gear, an extrusion ring and a sealing plate at the end of the protective sleeve, so that the nozzle can be wrapped inside, thereby protecting the nozzle and preventing impurities such as dust from entering the injection molding barrel from the opening of the nozzle or adhering to the outside of the nozzle. When the extrusion ring is squeezed by the mold mechanism, the rotating gear can be driven to rotate through the limit column and the spiral groove, and finally the two sealing doors can be driven to slide in opposite directions, so that the protective sleeve can be automatically opened. Not only will it not affect the insertion of the nozzle into the mold mechanism, but it also does not require external electrical components for control. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 1 It is a structural schematic diagram of the injection molding machine of the present invention;

[0028] Figure 2 It is a schematic diagram of the exploded structure of the injection molding barrel and the telescopic protective tube in the injection molding machine of the present invention;

[0029] Figure 3 It is a structural schematic diagram of a telescopic protective tube and its connecting parts in an injection molding machine of the present invention;

[0030] Figure 4 for Figure 3 Schematic diagram of the top-down structure;

[0031] Figure 5 for Figure 4 A schematic diagram of the structure enlargement at the center A;

[0032] Figure 6 for Figure 3 Schematic diagram of the cross-section structure;

[0033] Figure 7 for Figure 6 A schematic diagram of the structure enlarged at B in the middle;

[0034] Figure 8 It is a schematic diagram of the exploded structure of the rotating gear and its connecting parts in the injection molding machine of the present invention;

[0035] Fig. 9 It is a schematic diagram of the exploded structure of the sealing plate and the semicircular plate in the injection molding machine of the present invention.

[0036] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0037] 1. Injection molding machine; 2. Mold mechanism; 3. Injection molding barrel; 4. Nozzle; 5. Telescopic protective tube; 51. Outer tube; 52. Inner tube; 53. Limiting slot; 54. Limiting piece; 541. Fixed shaft; 542. Limiting rod; 543. Limiting tooth; 544. Fourth spring; 55. Third spring; 6. Extrusion plate; 61. Limiting slide groove; 7. Rotating gear; 8. First rack; 9. Second rack; 10. Sealing plate; 101. Inserting groove; 102. Embedding groove; 11. Spiral groove; 12. Extrusion ring; 13. Limiting column; 14. Limiting ring; 15. First spring; 16. T-shaped limiting strip; 17. Semicircular plate; 171. Limiting slot; 172. Limiting strip; 18. Connecting rod; 19. Extrusion block; 20. Abutting rod; 21. Abutting block; 22. Second spring. DETAILED DESCRIPTION

[0038] 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.

[0039] This embodiment takes the production process of cataract prevention presbyopia lenses as an example:

[0040] The weight ratio of the raw material components of the cataract prevention presbyopia lens in this embodiment is:

[0041] Base material 97.66%, initiator 0.28%, fluorescent whitening powder (agent) 0.03%, HS-16# powder 0.03%, UV powder 0.50%, blue agent 0.60% and red agent 0.90%, i.e. NK-55C monomer 9766g, initiator 28g, 2.5-bis(5-tert-butyl-2-benzoxazolyl)thiophene or 2.2′-(4.4′-distyryl)bisbenzoxazole 3g, HS-16# powder 3g, UV powder 50g, blue agent 60g, red agent 90g;

[0042] Then, 2.5-bis(5-tert-butyl-2-benzoxazolyl)thiophene or 2.2′-(4.4′-diphenylethylene)bisbenzoxazole and HS-16# powder are mixed and reacted to remove toxins, and then monomers are added, and then UV powder, blue agent and red agent are added and stirred evenly; and after heating in an 80°C water bath for 30 minutes, the temperature is lowered to 30°C, and initiator IPP is added and stirred evenly to form a molten raw material, and the molten raw material is injected into the injection molding machine 1 for injection molding.

[0043] like Figure 1-9 As shown, in this embodiment, the injection molding machine 1 includes a mold mechanism 2 and an injection molding barrel 3, a nozzle 4 and a telescopic protective tube 5 are installed at one end of the injection molding barrel 3, the telescopic protective tube 5 is arranged outside the nozzle 4, and an extrusion plate 6 with a hollow interior and first through holes at both ends is installed at one end of the telescopic protective tube 5, and a rotating gear 7 is rotatably connected to a side of the inner cavity of the extrusion plate 6 away from the injection molding barrel 3, and a second through hole that cooperates with the nozzle 4 is opened in the middle of the rotating gear 7, and the top and bottom of the rotating gear 7 are respectively rotatably connected to the first rack 8 and the second rack 9, and the first rack 8 and the second rack 9 are respectively connected to The top and bottom of the inner cavity of the extrusion plate 6 are slidably connected, and the first rack 8 and the second rack 9 are respectively fixedly connected with mutually matching sealing plates 10 for sealing the first through hole on one side close to the injection barrel 3. A spiral groove 11 is opened on the inner wall of the rotating gear 7, and an extrusion ring 12 with two ends passing through is slidably connected to the inner wall of the rotating gear 7. A limiting column 13 that cooperates with the spiral groove 11 is arranged on the outer wall of the extrusion ring 12, and a limiting ring 14 is arranged on the end of the extrusion ring 12 away from the extrusion plate 6. A first spring 15 is sleeved on the outer wall of the extrusion ring 12, and the first spring 15 is located between the limiting ring 14 and the extrusion plate 6.

[0044] In this embodiment, in order to ensure the sliding stability of the first rack 8 and the second rack 9, T-shaped limit bars 16 are provided on the top of the first rack 8 and the bottom of the second rack 9, and limiting grooves 61 that cooperate with the T-shaped limit bars 16 are provided on the top and bottom of the inner cavity of the extrusion plate 6. The T-shaped limit bars can limit the positions of the first rack and the second rack respectively. In particular, the T-shaped support can play a role of suspension support for the first rack located above, thereby ensuring the stability of the first rack.

[0045] In this embodiment, in order to enable the injection molding barrel to stir the material in the injection molding barrel to prevent the material from solidifying while waiting for injection molding, the following structure is used to block the nozzle, so that when the spiral feeder in the injection molding barrel is working, the material will not flow out of the nozzle. Therefore, the inner cavity of the sealing plate 10 is a hollow structure, and a semicircular plate 17 for blocking the nozzle 4 is provided on one side of the sealing plate 10 close to the nozzle 4. A connecting rod 18 is fixedly connected to the side of the semicircular plate 17 away from the nozzle 4, and one end of the connecting rod 18 is inserted into the inner cavity of the sealing plate 10. An extrusion block 19 is provided, and the connecting rod 18 is slidably connected to the sealing plate 10. An abutment rod 20 is staggeredly provided on the side where the two sealing plates 10 are close to each other. An abutment block 21 that cooperates with the extrusion block 19 is provided at the free end of the abutment rod 20. An insertion groove 101 that cooperates with the abutment block 21 is provided on the side wall of the sealing plate 10. Mutually matching inclined surfaces are provided on the side where the extrusion block 19 and the abutment block 21 are close to each other. A second spring 22 is sleeved on the outer wall of the connecting rod 18, and the second spring 22 is located inside the sealing plate 10.

[0046] In this embodiment, in order to prevent the semicircular plate from protruding from the surface of the sealing plate, the sealing plate 10 is recessed inwardly to form an embedding groove 102 that matches the semicircular plate 17 .

[0047] In this embodiment, in order to improve the sealing and connection strength between the two semicircular plates, a limiting groove 171 and a limiting strip 172 that cooperate with each other are respectively provided on the side where the two semicircular plates 17 are close to each other.

[0048] In this embodiment, in order to ensure that when the limit ring abuts against the mold mechanism, the extrusion ring slides first, and then drives the telescopic protection tube to expand and contract after the extrusion ring slides into place, the telescopic protection tube 5 includes a slidably connected outer tube 51 and an inner tube 52, the outer tube 51 is connected to the injection barrel 3, the inner tube 52 is connected to the extrusion plate 6, and both sides of the outer walls of the outer tube 51 and the inner tube 52 are symmetrically provided with limit grooves 53, and the extrusion plate 6 is slidably connected with a limit member 54 that cooperates with the two limit grooves 53. When the two sealing plates 10 slide in a direction away from each other, the two sealing plates 10 respectively push the two limit members 54 out of the limit grooves. The outer walls of the groove 53, the outer tube 51 and the inner tube 52 are all sleeved with electric heating sleeves, and the electric heating sleeves can heat and keep the nozzle warm, so as to avoid the low temperature of the material in the nozzle and cause the material to solidify and clog, wherein the limit member 54 includes a fixed shaft 541 fixed to the inner wall of the extrusion plate 6, the fixed shaft 541 is slidably connected to the limit rod 542, one end of the limit rod 542 passes through the inner cavity of the extrusion plate 6 and is provided with a limit tooth 543 that cooperates with the two limit slots 53, the outer wall of the fixed shaft 541 is sleeved with a fourth spring 544, and the fourth spring 544 is located between the limit rod 542 and the inner wall of the extrusion plate 6.

[0049] In this embodiment, in order to enable the telescopic protection tube to return to its original position faster, a third spring 55 is sleeved on the outer wall of the telescopic protection tube 5 .

[0050] The specific injection molding process of the above injection molding machine is as follows:

[0051] During injection molding, the injection barrel 3 is slid toward the mold mechanism 2, so that the limiting ring 14 first contacts the surface of the mold mechanism 2, thereby pushing the limiting ring 14 and the extrusion ring 12 to slide inside the rotating gear 7, and the rotating gear 7 is driven to rotate through the cooperation between the limiting column 13 and the spiral groove 11, so that the first rack 8 and the second rack 9 are driven to slide in a direction away from each other through the rotating gear 7, so that the two sealing plates 10 slide relatively to open the first through hole of the extrusion plate 6;

[0052] During the relative sliding of the two sealing plates 10, the sealing plate 10 gradually contacts the limit rod 542 and pushes the limit rod 542 and the limit tooth 543 to slide, thereby causing the limit tooth 543 to disengage from the telescopic protective tube 5, so that the inner tube 52 and the outer tube 51 of the telescopic protective tube 5 can slide relative to each other (i.e., telescope). At this time, the injection barrel 3 continues to slide toward the mold mechanism 2, and as the telescopic protective tube 5 contracts, the nozzle 4 can gradually pass through the first through hole of the telescopic protective tube 5 and be inserted into the mold mechanism 2 for injection molding.

[0053] After the injection molding is completed, the injection molding barrel 3 gradually returns to its original position so that the nozzle 4 gradually slides back into the telescopic protective tube 5, and at this time, the telescopic protective tube 5 gradually returns to its original position under the action of the restoring force of the third spring 55. In this process, the extrusion ring 12 loses the extrusion force during the gradual return of the nozzle 4 and will gradually return to its original position under the action of the restoring force of the first spring 15, and will also drive the rotating gear 7 to rotate in the opposite direction, that is, the two sealing plates 10 slide close to each other and abut against the outer wall of the nozzle 4, so that the extrusion ring 12 will not slide at this stage until the nozzle 4 is completely separated from the two sealing plates 10 and then continues to slide. At this time, the telescopic protective tube 5 is completely returned, and the limiting tooth 543 is again inserted into the limiting groove 53 of the inner tube 52 and the outer tube 51, thereby completing the fixation of the telescopic protective tube 5. After the nozzle 4 is separated from the sealing plate 10, the first spring 15 continues to drive the extrusion ring 12 to return, so that the rotating gear 7 continues to rotate, so that the sealing plate 10 continues to slide and closes the first through hole of the extrusion plate 6.

[0054] When the two sealing plates 10 gradually abut against each other, the abutment rod 20 and the abutment block 21 on the side wall of the sealing plate 10 are gradually inserted into the corresponding insertion grooves and the extrusion block 19 and the connecting rod 18 are pushed to slide through the inclined surface of the abutment block 21, thereby gradually pushing out the semicircular plate 17 until the two sealing plates 10 complete the abutment. At this time, the two semicircular plates 17 are completely pushed out and abut against the opening of the nozzle 4, and at this time, the limiting strips 172 of the two semicircular plates 17 are inserted into the limiting groove 171 to strengthen the strength of the semicircular plate 17.

[0055] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0056] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A production device for preventing cataract lenses, characterized in that: The invention comprises an injection molding machine (1), wherein the injection molding machine (1) comprises a mold mechanism (2) and an injection molding barrel (3), wherein a nozzle (4) and a telescopic protective tube (5) are installed at one end of the injection molding barrel (3), wherein the telescopic protective tube (5) is arranged outside the nozzle (4), wherein an extrusion plate (6) which is hollow inside and provided with first through holes at both ends is installed at one end of the telescopic protective tube (5), wherein a side of the inner cavity of the extrusion plate (6) away from the injection molding barrel (3) is rotatably connected to a rotating gear (7), and a second through hole which cooperates with the nozzle (4) is provided in the middle of the rotating gear (7), and a first rack (8) and a second rack (9) are rotatably connected at the top and bottom of the rotating gear (7), respectively, and the first rack (8) and the second rack (9) are respectively connected to the nozzle (4). The top and bottom of the inner cavity of the extrusion plate (6) are slidably connected, and the first rack (8) and the second rack (9) are respectively fixedly connected to mutually matching sealing plates (10) for sealing the first through hole on one side close to the injection molding barrel (3). The inner wall of the rotating gear (7) is provided with a spiral groove (11), and the inner wall of the rotating gear (7) is slidably connected with an extrusion ring (12) with two ends passing through. The outer wall of the extrusion ring (12) is provided with a limiting column (13) that matches the spiral groove (11), and the end of the extrusion ring (12) away from the extrusion plate (6) is provided with a limiting ring (14). The outer wall of the extrusion ring (12) is sleeved with a first spring (15), and the first spring (15) is located between the limiting ring (14) and the extrusion plate (6).

2. The production equipment for preventing cataract lenses according to claim 1, characterized in that: The top of the first rack (8) and the bottom of the second rack (9) are both provided with T-shaped limit strips (16), and the top and bottom of the inner cavity of the extrusion plate (6) are both provided with limit sliding grooves (61) that cooperate with the T-shaped limit strips (16).

3. The production equipment for preventing cataract lenses according to claim 1, characterized in that: The inner cavity of the sealing plate (10) is a hollow structure. A semicircular plate (17) for blocking the nozzle (4) is provided on a side of the sealing plate (10) close to the nozzle (4). A connecting rod (18) is fixedly connected to a side of the semicircular plate (17) away from the nozzle (4). One end of the connecting rod (18) is inserted into the inner cavity of the sealing plate (10) and is provided with an extrusion block (19). The connecting rod (18) is slidably connected to the sealing plate (10). The sides of the two sealing plates (10) close to each other are staggered. An abutment rod (20) is provided at the position, and an abutment block (21) that cooperates with the extrusion block (19) is provided at the free end of the abutment rod (20); an insertion groove (101) that cooperates with the abutment block (21) is provided on the side wall of the sealing plate (10); a side surface where the extrusion block (19) and the abutment block (21) are close to each other is provided with a mutually cooperating inclined surface; and a second spring (22) is sleeved on the outer wall of the connecting rod (18), and the second spring (22) is located inside the sealing plate (10).

4. The production equipment for preventing cataract lenses according to claim 3, characterized in that: The sealing plate (10) is recessed inwardly to form an embedding groove (102) adapted to the semicircular plate (17).

5. The production equipment for preventing cataract lenses according to claim 3, characterized in that: A mutually matching limiting groove (171) and a limiting strip (172) are respectively provided on the mutually adjacent sides of the two semicircular plates (17).

6. The production equipment for preventing cataract lenses according to claim 1, characterized in that: The telescopic protective tube (5) comprises an outer tube (51) and an inner tube (52) which are slidably connected, the outer tube (51) being connected to the injection molding barrel (3), and the inner tube (52) being connected to the extrusion plate (6), both sides of the outer walls of the outer tube (51) and the inner tube (52) being symmetrically provided with limit slots (53), the extrusion plate (6) being slidably connected with a limit piece (54) which cooperates with the two limit slots (53), when the two sealing plates (10) slide in a direction away from each other, the two sealing plates (10) respectively push the two limit pieces (54) out of the limit slots (53), and the outer walls of the outer tube (51) and the inner tube (52) are both sheathed with an electric heating sleeve.

7. The production equipment for preventing cataract lenses according to claim 5, characterized in that: A third spring (55) is sleeved on the outer wall of the telescopic protection tube (5).

8. The production equipment for preventing cataract lenses according to claim 6, characterized in that: The limiting member (54) comprises a fixed shaft (541) fixedly connected to the inner wall of the extrusion plate (6); the fixed shaft (541) is slidably connected to a limiting rod (542); one end of the limiting rod (542) passes through the inner cavity of the extrusion plate (6) and is provided with a limiting tooth (543) that cooperates with two limiting slots (53); the outer wall of the fixed shaft (541) is sleeved with a fourth spring (544), and the fourth spring (544) is located between the limiting rod (542) and the inner wall of the extrusion plate (6).

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