A forming die for a micro motor part housing

Abstract

The utility model relates to micro motor technical field, and disclose a kind of forming die of micro motor parts shell, including bottom plate, pedestal, the upper surface of the pedestal is formed with placing groove, the inside of placing groove is provided with shell body, the inside of shell body is provided with back cover, the top of pedestal is provided with the fixed block coaxially arranged with it, the bottom end of fixed block is provided with multiple rivet knives that are circumferentially distributed, every rivet knife is contacted with the edge of shell body, and the bottom end of every rivet knife is made edge treatment. This kind of forming die of micro motor parts shell, setting multiple circumferentially distributed edge rivet knives and the progressive riveting design of aluminium shell body edge, rivetless connection is realized, and the edge structure of rivet knife makes shell body edge produce uniform deformation, forms the deformation area that is completely fitted with back cover edge, avoids the crack risk caused by rivet stress concentration in traditional riveting process.

Description

Technical Field

[0001] This utility model relates to the field of micro motor technology, specifically to a molding die for the shell of a micro motor part. Background Technology

[0002] Micro motors, also known as miniature motors, are motors with a diameter of less than 160mm or a rated power of less than 750mW. Micro motors are commonly used in control systems or transmission mechanical loads to perform functions such as detection, analysis, amplification, execution, or conversion of electromechanical signals or energy.

[0003] An existing patent (publication number: CN211701793U) discloses a riveting device for the front and rear end covers of a motor. The device includes a worktable, a gas spring mounted in the center of the worktable, a positioning seat mounted on top of the gas spring, a motor placed on the positioning seat, a positioning groove machined on the top of the positioning seat, a through hole machined through the center of the bottom surface of the positioning groove to the bottom of the positioning seat, a limiting groove machined on the top of the positioning seat, and a through hole I machined through the bottom surface of the limiting groove to the bottom of the positioning seat. A top pressure rod is movably installed within the through hole I. A stamping mechanism is positioned directly above the positioning seat. During assembly, the motor is placed on the positioning seat for positioning. Then, the stamping mechanism moves downwards, and the bottom of the pressure rod contacts the top of the rivet, applying a downward force. The motor and positioning seat move downwards, and the top of the pressure rod extends into the inner hole I of the rivet. The hollow part of the rivet's tail is squeezed and flipped outwards, forming a snap-fit ​​to secure the front and rear end covers of the motor. By setting up a positioning seat and cooperating stamping mechanisms and top pressure rods, the riveting process of the front and rear end covers of the motor is automatically completed, changing the traditional bolt connection method and facilitating installation.

[0004] During use, the above-mentioned device uses the positioning seat and the upper and lower cooperating stamping mechanism and top pressure rod to complete the riveting of the front and rear covers of the motor. However, the size of the cavity inside the positioning seat is fixed, making it difficult to adapt to motor housings of different sizes. Furthermore, rivets are required to fix the housing to the rear cover, which increases the additional material cost and the rivet pre-installation process. Utility Model Content

[0005] To address the shortcomings of existing technologies, this utility model provides a molding die for the housing of a micro motor component, which has advantages such as rivetless connection and riveting of motor housings of different sizes, thus solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a molding die for a micro motor part housing, comprising a base plate and a base, wherein a placement groove is formed on the upper surface of the base, a housing body is disposed inside the placement groove, a rear cover is disposed inside the housing body, a fixing block is disposed on the upper part of the base and coaxially disposed therewith, and a plurality of circumferentially distributed rivets are disposed at the bottom end of the fixing block, each rivet contacting the edge of the housing body, and the bottom end of each rivet is beveled; The base has two cavities that communicate with the placement slot. Each cavity has a clip that holds the outer shell. The corresponding side of each clip is arc-shaped and fits the circumference of the outer shell. An auxiliary component that drives the clip to slide is provided between the base and the fixing block.

[0007] Furthermore, the bottom end of the fixing block is provided with multiple slots, each rivet is slidably connected to the corresponding slot, and multiple screws are rotatably connected to the circumferential surface of the fixing block. The other end of each screw is rotatably connected to the inner wall of the corresponding slot, and the upper end of each rivet is threadedly connected to the upper end of the corresponding screw.

[0008] Through the above scheme, the thread adjustment mechanism composed of the slot and the screw realizes the adjustable position of the rivet in the slot, which facilitates the riveting work of shells of different sizes.

[0009] Furthermore, the auxiliary component also includes two sliding rods that are slidably inserted into the upper end of the fixed block. The bottom ends of the two sliding rods are fixedly connected to pressure blocks. The bottom ends of the two pressure blocks are beveled. The upper surface of the base is provided with slots that communicate with the two cavities. The two pressure blocks are slidably inserted into the two slots respectively. The opposite sides of the two clips are fixedly connected to contact blocks with a triangular structure. The bottom ends of the two pressure blocks are in contact with the corresponding contact blocks.

[0010] Through the above scheme, the beveled structure of the pressure block and the triangular inclined surface of the contact block form a wedge-shaped transmission mechanism. When the fixed block is pressed down, the pressure block pushes the contact block through the inclined surface to generate a horizontal component force, which drives the clamp to move centripetally to achieve adaptive clamping.

[0011] Furthermore, the auxiliary component also includes two buffer springs fixedly connected to the upper surfaces of the pressure blocks, and the other ends of the two buffer springs are fixedly connected to the fixed blocks.

[0012] Through the above scheme, the buffer spring can use its own deformation force to buffer the pressure when the pressure block and the contact block come into contact, and prevent the continuous movement of the pressure block after the clamping part comes into contact with the outer shell body, which would cause the clamping part to exert excessive pressure on the outer shell and cause damage.

[0013] Furthermore, the auxiliary component also includes multiple return springs fixedly connected to the opposite sides of the two clips, and each return spring is fixedly connected to the inner wall of the corresponding cavity.

[0014] The reset spring designed in this way can drive the clamping part back into the cavity under the action of the deformation force of the reset spring after the riveting work is completed, thereby releasing the restriction on the outer shell body.

[0015] Furthermore, the base has two T-shaped chambers inside, both of which are connected to the placement groove. The placement groove has a slidably connected top block for ejecting the outer shell body. The bottom end of the outer shell body is in contact with the top block. The two chambers are respectively provided with ejection components for ejecting the outer shell body. Both ejection components are connected to the top block.

[0016] Furthermore, the discharge assembly includes sliding columns that are slidably connected to the inner wall of the cavity. The middle of each of the two sliding columns has an annular protrusion structure that contacts the inner wall of the cavity. A discharge spring is fixedly connected between the upper end of the sliding column and the interior of the cavity, and the middle of the sliding column is fixedly connected to the top block.

[0017] With the above scheme, the discharge assembly can push the outer shell body out through the sliding column and the top block under the action of the discharge spring deformation force, thereby popping out the riveted outer shell body.

[0018] Furthermore, a card holder is fixedly connected to the upper surface of the base, and the card holder is coaxially arranged with the base. A slot hole is formed in the central area of ​​the bottom wall of the placement groove, penetrating the base. A rotating shaft is provided inside the outer shell, and the bottom end of the rotating shaft passes through the slot hole and is located in the card holder. A positioning hole is formed at the bottom end of the fixing block, and the upper end of the rotating shaft is located in the positioning hole.

[0019] The above scheme, with the cooperation of the card holder and the slot, can initially position the outer shell by means of the limiting pivot, so that the outer shell body is centered inside the placement slot.

[0020] Furthermore, multiple guide rods are fixedly connected to the upper surface of the base plate, and the multiple guide rods are distributed in a matrix. A connecting plate is fixedly connected to the circumferential surface of the fixing block. The upper ends of the multiple guide rods are slidably inserted into multiple corners of the connecting plate. The middle part of the multiple guide rods is a ring-shaped protrusion structure. A boosting spring is fixedly connected to the upper surface of each ring-shaped protrusion structure. The other end of each boosting spring is fixedly connected to the connecting plate.

[0021] The above scheme provides guidance and limitation for the vertical movement of the connecting plate, enabling the fixed block to move vertically stably, while the assist spring provides assistance for the resetting of the connecting plate.

[0022] Compared with the prior art, the technical solution of this utility model has the following beneficial effects: This molding die for a micro motor component housing features a progressive riveting design with multiple circumferentially distributed beveling rivets on the edge of the aluminum housing body, achieving rivet-free connection. The beveling structure of the rivets causes uniform deformation of the housing body edge, forming a deformation area that perfectly fits the edge of the back cover, avoiding the risk of cracking caused by stress concentration in rivets in traditional riveting processes. Secondly, the clamping scheme combining a wedge-shaped transmission mechanism and a buffer spring, through the linkage between the beveling of the pressure block and the triangular inclined surface of the contact block, achieves automatic adjustment of the clamping force by the centripetal movement of the clamping part, enabling the clamping of housing bodies of different diameters. Finally, after the riveting is completed, the sliding column pushes the top block upward under the action of the discharge spring, automatically ejecting the molded housing from the placement slot for easy handling by the staff. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of this application; Figure 2 Cross-sectional view of the overall structure of this application Figure 1 ; Figure 3 Cross-sectional view of the overall structure of this application Figure 2 ; Figure 4 For this application Figure 3 Enlarged schematic diagram of the structure at point A; Figure 5 This is a schematic diagram of the fixed block structure of this application; Figure 6 This is a sectional view of the base structure of this application; Figure 7 This is a schematic diagram of the top block structure of this application; Figure 8 This is a schematic diagram of the card structure for this application.

[0024] In the picture: 1. Base plate; 2. Base; 3. Placement slot; 4. Outer shell body; 5. Back cover; 6. Fixing block; 7. Rivet; 8. Cavity; 9. Clip; 10. Auxiliary components; 1001, slide bar; 1002, pressure block; 1003, slot; 1004, contact block; 1005, buffer spring; 1006, return spring; 11. Slot; 12. Screw; 13. Chamber; 14. Top block; 15. Discharge assembly; 1501, Sliding column; 1502, Discharge spring; 16. Card holder; 17. Slot; 18. Rotating shaft; 19. Positioning hole; 20. Guide rod; 21. Connecting plate; 22. Assist spring. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Please see Figures 1-8 This embodiment provides a molding die for a micro motor component housing, comprising a base plate 1 and a base 2. A placement groove 3 is formed on the upper surface of the base 2, and a housing body 4 is disposed inside the placement groove 3. The housing body 4 is made of aluminum, and a rear cover 5 is disposed inside the housing body 4. A fixing block 6 is coaxially disposed above the base 2, and multiple circumferentially distributed rivets 7 are disposed at the bottom end of the fixing block 6. Each rivet 7 contacts the edge of the housing body 4, and the bottom end of each rivet 7 is chamfered. The rivets 7 can move downwards from the fixing block 6. At the same time, multiple rivets 7 contact the upper end of the outer shell body 4 and apply pressure to the upper edge of the outer shell body 4, causing the upper end of the outer shell body 4 to deform. This causes the deformed part of the outer shell body 4 to contact the back cover 5, fixing the back cover 5 to the outer shell body 4, thus achieving a rivetless connection. The beveled edge design of the rivets 7 enables progressive riveting, avoiding cracks in the aluminum outer shell body 4 due to stress concentration. At the same time, the circumferentially distributed rivets 7 form a uniform radial pressure field, ensuring that the deformed area is completely fitted with the edge of the back cover 5, achieving a rivetless connection.

[0027] The base 2 has two cavities 8 that communicate with the placement slot 3. Each cavity 8 has a slidably connected clamping member 9 that holds the outer shell 4. One side of each clamping member 9 is arc-shaped and conforms to the circumference of the outer shell 4. The arc-shaped surfaces of both clamping members 9 are made of rubber. An auxiliary component 10 is provided between the base 2 and the fixing block 6 to drive the clamping members 9 to slide. With the assistance of the auxiliary component 10, the clamping members 9 can slide towards the center of the placement slot 3 and clamp the outer shell 4, thus achieving the clamping and securing of different outer shells. The fixed block 6 is designed to facilitate riveting of micro motor housings of different sizes. Multiple slots 11 are provided at the bottom of the fixed block 6, and each rivet 7 is slidably connected to its corresponding slot 11. Multiple screws 12 are rotatably connected to the circumferential surface of the fixed block 6, with the other end of each screw 12 rotatably connected to the inner wall of its corresponding slot 11. The upper end of each rivet 7 is threadedly connected to the upper end of its corresponding screw 12. The threaded adjustment mechanism formed by the slots 11 and the screws 12 allows for adjustable position of the rivet 7 within the slots 11, facilitating riveting of housings of different sizes.

[0028] The auxiliary component 10 also includes two sliding rods 1001 slidably inserted into the upper end of the fixing block 6. A pressure block 1002 is fixedly connected to the bottom end of each sliding rod 1001. The bottom ends of both pressure blocks 1002 are chamfered. The upper surface of the base 2 has slots 1003 communicating with the two cavities 8. The two pressure blocks 1002 are slidably inserted into the two slots 1003. A triangular contact block 1004 is fixedly connected to the opposite side of each of the two clamping pieces 9. The bottom ends of the two pressure blocks 1002 contact the corresponding contact block 1004. The chamfered structure of the pressure block 1002 and the triangular inclined surface of the contact block 1004 form a wedge-shaped transmission mechanism. When the fixing block 6 is pressed down, the pressure block 1002 pushes the contact block 1004 through its inclined surface, generating a horizontal component force that drives the clamping piece 9 to move centripetally, achieving adaptive clamping. The auxiliary component 10 also includes two pressure blocks 1002. The upper surface is fixedly connected to buffer springs 1005 respectively. The other end of each buffer spring 1005 is fixedly connected to the fixing block 6. The buffer spring 1005 can use its own deformation force to buffer the pressure when the pressure block 1002 contacts the contact block 1004, so as to prevent the clamp from being damaged due to excessive squeezing force on the outer shell after the clamping part contacts the outer shell body 4 due to the continuous movement of the pressure block 1002. The auxiliary component 10 also includes multiple return springs 1006 fixedly connected to the opposite side of the two clamping parts 9 respectively. Each return spring 1006 is fixedly connected to the inner wall of the corresponding cavity 8. The deformation force of the buffer spring 1005 is greater than that of the return spring 1006. The return spring 1006 can drive the clamping part back into the cavity 13 under the action of the deformation force of the return spring 1006 after the riveting work is completed, thereby releasing the restriction on the outer shell body 4.

[0029] The base 2 has two T-shaped chambers 13 inside, both of which are connected to the placement groove 3. The placement groove 3 has a sliding block 14 for ejecting the outer shell 4. The bottom end of the outer shell 4 is in contact with the top block 14. The two chambers 13 are respectively provided with ejection components 15 for ejecting the outer shell 4. Both ejection components 15 are connected to the top block 14. The ejection components 15 include sliding columns 1501 that are slidably connected to the inner wall of the chamber 13. The middle part of each sliding column 1501 has an annular protrusion structure that is in contact with the inner wall of the chamber 13. The upper end of the sliding column 1501 is fixedly connected to the inside of the chamber 13 with an ejection spring 1502. The middle part of the sliding column 1501 is fixedly connected to the top block 14. The ejection components 15 can eject the outer shell 4 by pushing the top block 14 through the sliding column 1501 under the action of the deformation force of the ejection spring 1502, thereby ejecting the riveted outer shell 4.

[0030] A retaining seat 16 is fixedly connected to the upper surface of the base 2. The retaining seat 16 is coaxially arranged with the base 2. A slot 17 penetrating the base 2 is formed in the central area of ​​the bottom wall of the placement groove 3. A rotating shaft 18 is provided inside the outer shell. The bottom end of the rotating shaft 18 passes through the slot 17 and is located inside the retaining seat 16. A positioning hole 19 is formed at the bottom end of the fixing block 6. The upper end of the rotating shaft 18 is located inside the positioning hole 19. The fit between the retaining seat 16 and the slot 17 can initially position the outer shell by limiting the rotating shaft 18, so that the outer shell body 4 is centered inside the placement groove 3. Multiple guide rods 20 are fixedly connected to the upper surface of the base plate 1. The multiple guide rods 20 are distributed in a matrix. A connecting plate 21 is fixedly connected to the circumferential surface of the fixed block 6. The upper ends of multiple guide rods 20 are slidably inserted into multiple corners of the connecting plate 21. The middle part of each guide rod 20 has an annular protrusion structure. An assist spring 22 is fixedly connected to the upper surface of each annular protrusion structure. The other end of each assist spring 22 is fixedly connected to the connecting plate 21. The upper surface of the fixed block 6 is fixedly connected to the output end of the external linear drive device. The guide rods 20 can provide guidance and limit for the vertical movement of the connecting plate 21, so that the fixed block 6 can move vertically stably. The assist springs 22 can provide assistance for the resetting of the connecting plate 21.

[0031] The working principle of the above embodiment is as follows: In the preparation work, the staff places the outer shell body 4 into the placement slot 3 and inserts the rotating shaft 18 into the outer shell body 4. The bottom end of the rotating shaft 18 is inserted into the card seat 16 to achieve the initial positioning of the outer shell body 4. Then, the back cover 5 is put on the rotating shaft 18.

[0032] Subsequently, the external linear drive device drives the fixed block 6 to move vertically downwards, causing the two pressure blocks 1002 to be inserted into their corresponding slots 1003 and contact the corresponding contact blocks 1004. At this time, since the top block 14 is located in the middle of the placement groove 3, the two locking pieces 9 will be obstructed and remain stationary. When the fixed block 6 descends, the pressure of the pressure block 1002 on the contact block 1004 will act on the buffer spring 1005 to prevent hard contact between the pressure block 1002 and the contact block 1004. Subsequently, multiple rivets 7 will contact the upper end of the outer shell body 4 and push the top block 14 to slide in the placement groove 3, stretching the discharge spring 1502. When the top block 14 contacts the inner bottom wall of the placement groove 3, the two locking pieces 9 will no longer contact the top block 14. Under the deformation force of the corresponding return spring 1006, the pressure block 1002 will contact the corresponding contact block 1004, causing the two contact blocks 1004 to slide in the corresponding chamber 13 and contact the outer shell body 4. At this time, the return spring 1006 will be stretched. Since the arc-shaped structure of the two clips 9 is made of rubber, it can reduce the impact force when contacting the outer shell body 4. After the clips 9 contact the outer shell body 4, since the clips 9 are slidably connected to the chamber 13, it can prevent the upper end of the outer shell body 4 from swinging after being subjected to pressure. Finally, the rivet 7 makes hard contact with the outer shell body 4, and causes the upper end of the outer shell body 4 to deform in the contact area with the rivet 7, so that the deformed part of the outer shell body 4 contacts the back cover 5, and fixes the back cover 5 to the outer shell body 4.

[0033] After riveting is completed, the external linear drive device drives the fixed block 6 to reset, causing the pressure block 1002 to separate from the contact block 1004. At this time, the deformation force of the reset spring 1006 can drive the clamp 9 to reset. When the clamp 9 is fully reset, the deformation reset force of the discharge spring 1502 can drive the top block 14 to reset and pop out the outer shell body 4 to realize automatic discharge.

[0034] When riveting shells of different sizes, the position of the rivet 7 can be adjusted by rotating the screw 12. The operator can adjust multiple rivet 7 to the appropriate position by measuring the travel distance of the rivet 7 in the slot 11, and use the fitting 9 to clamp the shells of different sizes, so as to realize the riveting work of the shell body 4 of different sizes.

[0035] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0036] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A molding die for a housing of a micro motor component, comprising a base plate (1) and a base (2), characterized in that: The upper surface of the base (2) is formed with a placement groove (3), the inside of the placement groove (3) is provided with a shell body (4), the inside of the shell body (4) is provided with a back cover (5), a fixing block (6) is provided on the top of the base (2) and is coaxially arranged therewith, and a plurality of rivets (7) are provided at the bottom of the fixing block (6) in a circular arrangement, each rivet (7) is in contact with the edge of the shell body (4), and the bottom of each rivet (7) is beveled; The base (2) has two cavities (8) that communicate with the placement slot (3). The two cavities (8) are slidably connected to the housing body (4) with clamps (9). The corresponding side of the two clamps (9) is arc-shaped and fits the circumferential surface of the housing body (4). An auxiliary component (10) for driving the clamps (9) to slide is provided between the base (2) and the fixing block (6).

2. The molding die for a micro motor part housing according to claim 1, characterized in that: The bottom end of the fixing block (6) is provided with multiple slots (11), and each rivet (7) is slidably connected to the corresponding slot (11). Multiple screws (12) are rotatably connected to the circumferential surface of the fixing block (6). The other end of each screw (12) is rotatably connected to the inner wall of the corresponding slot (11), and the upper end of each rivet (7) is threadedly connected to the upper end of the corresponding screw (12).

3. The molding die for a micro motor part housing according to claim 1, characterized in that: The auxiliary component (10) also includes two sliding rods (1001) that are slidably inserted into the upper end of the fixing block (6). The bottom ends of the two sliding rods (1001) are fixedly connected to pressure blocks (1002). The bottom ends of the two pressure blocks (1002) are beveled. The upper surface of the base (2) is provided with slots (1003) that communicate with the two cavities (8). The two pressure blocks (1002) are slidably inserted into the two slots (1003). The two clips (9) are fixedly connected to a contact block (1004) with a triangular structure on opposite sides. The bottom ends of the two pressure blocks (1002) are in contact with the corresponding contact block (1004).

4. The molding die for a micro motor part housing according to claim 3, characterized in that: The auxiliary component (10) also includes two buffer springs (1005) fixedly connected to the upper surfaces of the two pressure blocks (1002), and the other ends of the two buffer springs (1005) are fixedly connected to the fixing block (6).

5. The molding die for a micro motor part housing according to claim 3, characterized in that: The auxiliary component (10) also includes multiple return springs (1006) fixedly connected to the opposite sides of two clips (9), and each return spring (1006) is fixedly connected to the inner wall of the corresponding cavity (8).

6. The molding die for a micro motor part housing according to claim 1, characterized in that: The base (2) has two T-shaped chambers (13) inside, both of which are connected to the placement groove (3). The placement groove (3) is slidably connected to a top block (14) for ejecting the outer shell body (4). The bottom end of the outer shell body (4) is in contact with the top block (14). The two chambers (13) are respectively provided with discharge components (15) for ejecting the outer shell body (4). Both discharge components (15) are connected to the top block (14).

7. The molding die for a micro motor part housing according to claim 6, characterized in that: The discharge assembly (15) includes a sliding column (1501) that is slidably connected to the inner wall of the chamber (13). The middle part of each of the two sliding columns (1501) has an annular protrusion structure and contacts the inner wall of the chamber (13). The upper end of the sliding column (1501) is fixedly connected to the inside of the chamber (13) with a discharge spring (1502). The middle part of the sliding column (1501) is fixedly connected to the top block (14).

8. The molding die for a micro motor part housing according to claim 1, characterized in that: A card holder (16) is fixedly connected to the upper surface of the base (2). The card holder (16) is coaxially arranged with the base (2). A slot (17) penetrating the base (2) is formed in the central area of ​​the bottom wall of the placement groove (3). A rotating shaft (18) is provided inside the outer shell. The bottom end of the rotating shaft (18) passes through the slot (17) and is located in the card holder (16). A positioning hole (19) is formed at the bottom end of the fixing block (6). The upper end of the rotating shaft (18) is located in the positioning hole (19).

9. The molding die for a micro motor part housing according to claim 1, characterized in that: Multiple guide rods (20) are fixedly connected to the upper surface of the base plate (1). The multiple guide rods (20) are distributed in a matrix. A connecting plate (21) is fixedly connected to the circumferential surface of the fixing block (6). The upper ends of the multiple guide rods (20) are slidably inserted into the multiple corners of the connecting plate (21). The middle part of the multiple guide rods (20) is a ring-shaped protrusion structure. A boosting spring (22) is fixedly connected to the upper surface of each ring-shaped protrusion structure. The other end of each boosting spring (22) is fixedly connected to the connecting plate (21).

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