Magnetron-guided forming die for non-ferrous metal powder

Abstract

The present application relates to the technical field of forming die, and discloses a non-ferrous metal powder forming die with magnetic control guiding, which comprises a guiding column and a sliding mechanism, the sliding mechanism comprises a contact assembly, the contact assembly comprises a hollow ball, first counterweight and second counterweight are fixedly installed inside the hollow ball, and the outer surface of the hollow ball is in rolling contact with the outer wall of the guiding column; the first counterweight and the second counterweight are different in mass, and are arranged eccentrically inside the hollow ball, so that the center of mass of the hollow ball deviates from the geometric center thereof; the hollow ball and the guiding column are in rolling contact, sliding friction is converted into rolling friction, the movement resistance and wear of the guiding pair are reduced, in the process of rolling, the hollow ball forms dynamic disturbance to the magnetic field, the static blind area of the magnetic field caused by the intervention of the guiding structure is effectively eliminated, the magnetic field in the cavity is uniformly distributed, and internal crystal lattice defects caused by local orientation imbalance in the forming process of the powder are avoided.

Description

Technical Field

[0001] This invention belongs to the field of molding die technology, and particularly relates to a magnetically guided non-ferrous metal powder molding die. Background Technology

[0002] In the molding process of anisotropic products, magnetic field guiding technology is often used to make powder particles oriented during the pressing process, so as to improve the magnetic or mechanical properties of the molded parts. Such molds are usually equipped with a magnetic field generating module, which applies a directional magnetic field to the powder in the cavity during the mold closing and pressing process, while the sliding guide pair formed by the guide pillar and the guide sleeve ensures the alignment accuracy of the upper and lower molds.

[0003] In existing technologies, guide pairs generally adopt a rigid sliding fit structure; guide posts are usually made of high-hardness steel, and the inner wall of the guide sleeve is equipped with a wear-resistant bushing. The two rely on sliding friction to achieve guidance. In actual production, in order to ensure smooth guidance, the sliding pair needs to be lubricated regularly. However, the lubricant can easily seep into the cavity and contaminate the non-ferrous metal powder, affecting the purity of the molded part. More importantly, as a solid structure, the guide post will inevitably intervene in the magnetic field area generated by the magnetic field generating module. Since the guide post is usually made of magnetically conductive material, it will change the local magnetic field line distribution, forming a magnetic field blind zone or magnetic field disorder zone near the guide post. Even if a non-magnetically conductive material is used, the presence of a solid guide post will still block the closed loop of the magnetic field lines, resulting in a decrease in the uniformity of the magnetic field inside the cavity. Uneven magnetic field distribution will cause the powder particles to be inconsistently oriented during the molding process, which will lead to lattice defects or substandard performance anisotropy inside the molded part. Summary of the Invention

[0004] The purpose of this invention is to provide a magnetically guided non-ferrous metal powder forming mold to solve the technical problem of uneven magnetic field distribution caused by the introduction of a magnetic field into the guide column in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A magnetically guided non-ferrous metal powder forming mold includes a guide post and a sliding mechanism. The sliding mechanism includes a contact component, which comprises a hollow ball with a first counterweight and a second counterweight fixedly installed inside. The outer surface of the hollow ball makes rolling contact with the outer wall of the guide post. The first and second counterweights have different masses and are eccentrically arranged inside the hollow ball, causing the center of mass of the hollow ball to deviate from its geometric center. When the sliding mechanism moves up and down along the guide post, the hollow ball rolls along the outer wall of the guide post, converting sliding friction into rolling friction and creating dynamic disturbance to the magnetic field. Because the center of mass of the hollow ball deviates from its geometric center, the hollow ball generates oscillation of its rotation axis and axial movement during rolling, causing the contact point between the hollow ball and the guide post to change along a spatial spiral trajectory.

[0007] According to some embodiments, it further includes: a lower mold, fixedly connected to the guide post; and an upper mold, mounted on the sliding mechanism.

[0008] According to some embodiments, the sliding mechanism further includes a connecting component, which includes: a hollow slide tube fixedly connected to the upper mold; and a fixing cover fixedly installed on the hollow slide tube.

[0009] According to some embodiments, the contact assembly further includes: a fixing tube, fixedly mounted on the hollow slide tube; and a mounting base, slidably mounted inside the fixing tube and tactilely connected to the hollow ball.

[0010] According to some embodiments, the contact assembly further includes: a threaded post, which is fixedly connected to the mounting base and slidably connected to the fixing tube; and a screw, which is threadedly connected to the threaded post.

[0011] According to some embodiments, the sliding mechanism further includes a self-resetting drive assembly, which includes: a mounting bracket, fixedly connected to the hollow slide tube and rotatably connected to the screw; a rotating bracket, rotatably mounted on the hollow slide tube, on which a first gear is fixedly mounted; and a toggle plate, located inside the first gear and fixedly connected to the screw.

[0012] According to some embodiments, the self-resetting drive assembly further includes: a gear frame that meshes with the first gear and has a fixing plate fixedly mounted thereon; and a second spring, one end of which is fixedly connected to the mounting bracket and the other end of which is fixedly connected to the fixing plate.

[0013] According to some embodiments, it further includes: a magnetic ring, fixedly mounted on the guide post; the self-resetting drive assembly further includes: a magnetic block, fixedly mounted on the gear frame, and magnetically repelled by the magnetic ring.

[0014] According to some embodiments, the sliding mechanism further includes an air supply assembly, which includes: a hollow air supply box, fixedly installed on the hollow sliding tube, having a plurality of oblique holes through it; a pressure ring, slidably installed on the hollow air supply box, having an arc-shaped plate fixedly installed on it and slidably connected to the hollow air supply box; and a first spring, one end of which is fixedly connected to the hollow air supply box and the other end of which is fixedly connected to the arc-shaped plate.

[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0016] 1. This invention transforms sliding friction into rolling friction by setting hollow rolling balls to form rolling contact with guide columns, thereby reducing the motion resistance and wear of the guide pair. At the same time, the hollow rolling balls create dynamic disturbances to the magnetic field during rolling, effectively eliminating the static blind zone of the magnetic field caused by the intervention of the guide structure, making the magnetic field distribution in the cavity uniform, and avoiding internal lattice defects caused by local orientation imbalance of powder during the molding process.

[0017] 2. This invention uses a first counterweight and a second counterweight of different masses to be eccentrically arranged inside a hollow rolling ball, causing the center of mass of the hollow rolling ball to deviate from its geometric center. During the rolling process, the ball generates a oscillation of its rotation axis and axial movement, causing the contact point to change in a spatial spiral trajectory, thus avoiding localized uneven wear. At the same time, the instantaneous rolling speed changes periodically, creating a wide-frequency disturbance to the magnetic field, thus eliminating the hysteresis loop distortion problem that is difficult to overcome by a single-frequency disturbance.

[0018] 3. This invention uses a self-resetting drive assembly to drive the gear frame to move during mold closing by utilizing the magnetic repulsion between the magnetic block and the magnetic ring. The first gear drives the anti-threaded screw to rotate, causing the threaded column to move the mounting base and hollow ball towards the guide column. After the hollow ball wears down due to long-term use, the gap is automatically compensated to ensure that the hollow ball always keeps in close contact with the guide column, thus ensuring the continuous stability of guiding accuracy and magnetic field disturbance. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the assembly structure of the connecting component and the gas supply component in this invention;

[0022] Figure 3This is a schematic diagram of the internal structure of the hollow slide tube in this invention;

[0023] Figure 4 This is a schematic diagram of the internal structure of the fixed tube in this invention;

[0024] Figure 5 This is a schematic diagram of the internal structure of the hollow rolling ball in this invention;

[0025] Figure 6 This is a schematic diagram of the assembly structure of the gear frame and the second spring in this invention;

[0026] Figure 7 This is a schematic diagram of the assembly structure of the rotating frame and the screw in this invention;

[0027] Figure 8 This is a schematic diagram of the assembly structure of the gas supply component in this invention.

[0028] Reference numerals: 100, sliding mechanism; 110, connecting assembly; 111, hollow slide tube; 112, fixing cover; 120, air supply assembly; 121, hollow air supply box; 122, pressure ring; 123, arc plate; 124, first spring; 125, oblique hole; 130, self-resetting drive assembly; 131, gear frame; 132, mounting bracket; 133, second spring; 134, fixing plate; 135, magnet; 136, rotating frame; 137, first gear; 138, actuating plate; 140, contact assembly; 141, screw; 142, threaded column; 143, fixing tube; 144, mounting base; 145, hollow ball; 147, first counterweight; 148, second counterweight; 200, upper mold; 300, lower mold; 400, guide column; 500, magnetic ring. Detailed Implementation

[0029] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0030] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0032] This invention is described in detail with reference to the accompanying drawings. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not to scale. Furthermore, the accompanying drawings are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0033] Furthermore, it should be noted in the description of this invention that the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] Example 1: As Figures 1 to 8 As shown, a magnetically guided non-ferrous metal powder forming mold includes a guide post 400 and a sliding mechanism 100. The sliding mechanism 100 includes a contact component 140, which includes a hollow ball 145 with a first counterweight 147 and a second counterweight 148 fixedly installed inside. The outer surface of the hollow ball 145 rolls in contact with the outer wall of the guide post 400. The first counterweight 147 and the second counterweight 148 have different masses, and they are offset inside the hollow ball 145. The hollow ball 145 is arranged such that its center of mass is offset from its geometric center. When the sliding mechanism 100 moves up and down along the guide post 400, the hollow ball 145 rolls along the outer wall of the guide post 400, converting sliding friction into rolling friction and creating dynamic disturbance to the magnetic field. Because the center of mass of the hollow ball 145 is offset from its geometric center, the hollow ball 145 generates oscillation of its rotation axis and axial movement during the rolling process, causing the contact point between the hollow ball 145 and the guide post 400 to change in a spatial spiral trajectory.

[0036] It should be noted that the hollow ball 145 is made of a low-permeability magnetic material, such as permalloy. During the operation of the molding die, when the sliding mechanism 100 moves, the hollow ball 145 in the contact component 140 forms a rolling contact with the outer wall of the guide post 400, which transforms the traditional sliding friction into rolling friction, reducing motion resistance and wear. At the same time, the hollow ball 145 continuously cuts the magnetic field generated by the magnetic field generating module during the rolling process, forming dynamic disturbances, eliminating the static blind zone of the magnetic field caused by the intervention of the guide structure, making the magnetic field distribution in the cavity uniform, and avoiding internal lattice defects caused by local orientation imbalance of non-ferrous metal powder during the molding process.

[0037] Based on this, the first counterweight 147 and the second counterweight 148, which are eccentrically arranged inside the hollow ball 145, have different masses and are off-center from the geometric center, so that the center of mass of the hollow ball 145 does not coincide with its geometric center. When the hollow ball 145 rolls along the guide post 400, this eccentric structure causes it to oscillate on its own axis and move axially while revolving and rolling. On the one hand, this causes the contact point between the hollow ball 145 and the guide post 400 to change in a spatial spiral trajectory, avoiding local wear and greatly extending the service life of the guide pair. On the other hand, the oscillation of the rotation axis and the axial movement cause its instantaneous rolling speed to change periodically, forming a wide-frequency disturbance to the magnetic field, which can eliminate the problem of hysteresis loop distortion that is difficult to overcome by a single frequency disturbance.

[0038] like Figure 1 As shown, the lower mold 300 is fixedly connected to the guide post 400; the upper mold 200 is mounted on the sliding mechanism 100.

[0039] It should be noted that the upper mold 200 is mounted on the sliding mechanism 100, which can move up and down along the guide post 400, thereby driving the upper mold 200 and the lower mold 300 to complete the mold closing and opening actions.

[0040] like Figure 3 As shown, the sliding mechanism 100 also includes a connecting component 110, which includes a hollow slide tube 111 and a fixing cover 112; the hollow slide tube 111 is fixedly connected to the upper mold 200; and the fixing cover 112 is fixedly installed on the hollow slide tube 111.

[0041] like Figure 3 and Figure 4 As shown, the contact assembly 140 also includes a screw 141, a threaded post 142, a fixed tube 143, and a mounting base 144; the fixed tube 143 is fixedly mounted on the hollow slide tube 111; the mounting base 144 is slidably mounted inside the fixed tube 143, and the mounting base 144 is in rolling connection with the hollow ball 145.

[0042] It should be noted that the hollow ball 145 is in contact with the outer surface of the sliding mechanism 100. During the up-and-down sliding of the upper mold 200, the hollow ball 145 will move together, thereby assisting the upper mold 200 to move up and down by means of the rolling of the hollow ball 145 on the guide post 400.

[0043] like Figure 4 As shown, the contact assembly 140 also includes a threaded post 142 fixedly connected to the mounting base 144, the threaded post 142 being slidably connected to the fixed tube 143; and a screw 141 being threadedly connected to the threaded post 142.

[0044] like Figure 6 and Figure 7 As shown, the sliding mechanism 100 also includes a self-resetting drive assembly 130, which includes a gear frame 131, a mounting frame 132, a second spring 133, a fixing plate 134, a magnet 135, a rotating frame 136, a first gear 137, and a toggle plate 138. The mounting frame 132 is fixedly connected to the hollow slide tube 111 and rotatably connected to the screw 141. The rotating frame 136 is rotatably mounted on the hollow slide tube 111, and the first gear 137 is fixedly mounted on the rotating frame 136. The toggle plate 138 is located inside the first gear 137 and is fixedly connected to the screw 141.

[0045] The self-resetting drive assembly 130 also includes a gear frame 131 that meshes with the first gear 137, and a fixing plate 134 is fixedly mounted on the gear frame 131; one end of the second spring 133 is fixedly connected to the mounting bracket 132, and the other end of the second spring 133 is fixedly connected to the fixing plate 134.

[0046] like Figure 1 and Figure 6 As shown, the magnetic ring 500 is fixedly installed on the guide post 400; the magnetic block 135 is fixedly installed on the gear frame 131, and the magnetic block 135 and the magnetic ring 500 are magnetically repelled.

[0047] It should be noted that during the process of the upper mold 200 moving downwards to close with the lower mold 300, the sliding mechanism 100 also moves downwards along with the upper mold 200. When the upper mold 200 and the lower mold 300 are closed, since a magnetic ring 500 is fixedly installed on the guide post 400, the magnetic ring 500 is repelled by the magnetic force of the magnetic block 135. Thus, when the magnetic block 135 approaches the guide post 400, it will be acted upon by the magnetic force and move upwards. If the hollow ball 145 wears down due to long-term use, causing a gap between it and the outer surface of the guide post 400, the magnetic block 135 will drive the gear frame 131 to move upwards. The upward movement of the gear frame 131 will drive the first gear 137 to rotate. The rotation of the first gear 137 will cause the screw 141 to rotate through the actuating plate 138. Since the screw 141 has a reverse thread, the rotation of the screw 141 will cause the threaded post 141 to rotate. 42 drives the mounting base 144 and hollow ball 145 closer to the guide post 400, thereby ensuring that multiple hollow balls 145 can always be in contact with the guide post 400, stabilizing the up and down movement of the upper mold 200, avoiding gaps between the hollow balls 145 and the guide post 400, ensuring the stable disturbance of the magnetic field by the hollow balls 145, and when the upper mold 200 and the lower mold 300 complete the mold closing, the upper mold 200 moves away from the lower mold 300, so the magnetic block 135 will also move away from the magnetic ring 500, thus the gear frame 131 loses the repulsive magnetic force. At this time, the gear frame 131 will return to its original position under the action of the second spring 133, but because the first gear 137 reverses, it cannot act on the actuating plate 138, thus not driving the screw 141, and not causing the hollow balls 145 to return to their original position, ensuring the normal operation of the hollow balls 145.

[0048] The working principle of this embodiment:

[0049] Non-ferrous metal powder is placed into the cavity of the lower mold 300. The equipment is started to drive the sliding mechanism 100 to move the upper mold 200 down along the guide column 400 to perform the mold closing action.

[0050] When the sliding mechanism 100 moves downward, the hollow ball 145 of the contact component 140 rolls into contact with the outer wall of the guide post 400, converting sliding friction into rolling friction and reducing motion resistance. The first counterweight 147 and the second counterweight 148, which are eccentrically arranged inside the hollow ball 145, cause the center of mass to deviate from the geometric center. During rolling, the ball 145 generates a swaying of its rotation axis and axial movement. The contact point changes in a spatial spiral trajectory, avoiding local uneven wear. At the same time, it forms a wide-frequency dynamic disturbance to the magnetic field, eliminates the static blind zone of the magnetic field, ensures the uniformity of the magnetic field in the cavity, and makes the powder particles oriented.

[0051] During the mold closing process, the magnetic block 135 on the gear frame 131 moves down with the sliding mechanism 100 and approaches the magnetic ring 500. The magnetic forces of the two repel each other, pushing the gear frame 131 to move and stretching the second spring 133. The gear frame 131 drives the first gear 137 to rotate, which drives the screw 141 to rotate through the actuating plate 138. The screw 141 is threadedly engaged with the threaded post 142, pushing the mounting base 144 and the hollow ball 145 to move towards the guide post 400, automatically compensating for wear gaps and ensuring that the hollow ball 145 is always tightly attached to the guide post 400.

[0052] After the mold is closed and pressed, the drive sliding mechanism 100 drives the upper mold 200 to move up and open the mold; the magnetic block 135 moves away from the magnetic ring 500, the second spring 133 resets and drives the gear frame 131 back to its original position, the first gear 137 rotates in the opposite direction but does not drive the actuating plate 138, and the hollow ball 145 remains in contact with the guide post 400, waiting for the next molding operation.

[0053] Example 2: Figure 3 and Figure 8 As shown, while all other parts are the same as in Example 1, the difference between this example and Example 1 is that:

[0054] The sliding mechanism 100 also includes an air supply assembly 120, which includes a hollow air supply box 121, a pressure ring 122, an arc plate 123, a first spring 124, and oblique holes 125. The hollow air supply box 121 is fixedly installed on the hollow sliding tube 111, and multiple oblique holes 125 are provided through the hollow air supply box 121. The pressure ring 122 is slidably installed on the hollow air supply box 121, and an arc plate 123 that is slidably connected to the hollow air supply box 121 is fixedly installed on the pressure ring 122. One end of the first spring 124 is fixedly connected to the hollow air supply box 121, and the other end of the first spring 124 is fixedly connected to the arc plate 123.

[0055] The working principle of this embodiment:

[0056] When the upper mold 200 and the lower mold 300 open, the upper mold 200 moves away from the lower mold 300 and returns to its original position. During this process, the pressure ring 122 is squeezed. After the pressure ring 122 is squeezed, it will drive the arc plate 123 to squeeze the gas inside the hollow air supply box 121, so that the gas inside the hollow air supply box 121 is discharged. The discharged gas will act between the hollow slide tube 111 and the guide post 400 to clean the dust, impurities and other substances generated by the hollow ball 145 and the guide post 400, so as to avoid impurities affecting the mold closing of the upper mold 200 and the lower mold 300.

[0057] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0058] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A magnetically guided non-ferrous metal powder forming mold, comprising guide pillars, characterized in that, It also includes a sliding mechanism, the sliding mechanism comprising a contact component, the contact component comprising: A hollow ball, with a first counterweight and a second counterweight fixedly installed inside, and the outer surface of the hollow ball in rolling contact with the outer wall of the guide post; The first counterweight and the second counterweight have different masses, and they are eccentrically arranged inside the hollow sphere, causing the center of mass of the hollow sphere to deviate from its geometric center. When the sliding mechanism moves up and down along the guide post, the hollow ball rolls along the outer wall of the guide post, converting sliding friction into rolling friction and creating dynamic disturbance to the magnetic field. Since the center of mass of the hollow ball deviates from its geometric center, the hollow ball generates a spin axis swing and axial movement during the rolling process, causing the contact point between the hollow ball and the guide post to change in a spatial spiral trajectory.

2. The magnetically guided non-ferrous metal powder forming mold according to claim 1, characterized in that, Also includes: The lower mold is fixedly connected to the guide post; The upper mold is installed on the sliding mechanism.

3. The magnetically guided non-ferrous metal powder forming mold according to claim 2, characterized in that, The sliding mechanism further includes a connecting component, which comprises: A hollow sliding tube is fixedly connected to the upper mold; A fixing cover is fixedly installed on the hollow slide tube.

4. The magnetically guided non-ferrous metal powder forming mold according to claim 3, characterized in that, The contact assembly further includes: A fixing tube is fixedly installed on the hollow sliding tube; The mounting base is slidably installed inside the fixed tube and is rotatably connected to the hollow ball.

5. A magnetically guided non-ferrous metal powder forming mold according to claim 4, characterized in that, The contact assembly further includes: The threaded column is fixedly connected to the mounting base and slidably connected to the fixing tube. The screw is threadedly connected to the threaded post.

6. A magnetically guided non-ferrous metal powder forming mold according to claim 5, characterized in that, The sliding mechanism further includes a self-resetting drive component, which comprises: The mounting bracket is fixedly connected to the hollow slide tube and rotatably connected to the screw. A rotating frame is rotatably mounted on the hollow slide tube, and a first gear is fixedly mounted on it; The actuating piece is located inside the first gear and is fixedly connected to the screw.

7. A magnetically guided non-ferrous metal powder forming mold according to claim 6, characterized in that, The self-reset drive component also includes: A gear frame meshes with the first gear, and a fixing plate is fixedly mounted on it; The second spring has one end fixedly connected to the mounting bracket and the other end fixedly connected to the fixing plate.

8. A magnetically guided non-ferrous metal powder forming mold according to claim 7, characterized in that, Also includes: A magnetic ring is fixedly installed on the guide post; The self-reset drive component also includes: The magnetic block is fixedly mounted on the gear frame and is magnetically repelled by the magnetic ring.

9. A magnetically guided non-ferrous metal powder forming mold according to claim 3, characterized in that, The sliding mechanism further includes an air supply component, which includes: A hollow air supply box is fixedly installed on the hollow sliding tube, and multiple oblique holes are opened through it; A pressure ring is slidably mounted on the hollow air supply box, and an arc-shaped plate that is slidably connected to the hollow air supply box is fixedly mounted on it. The first spring has one end fixedly connected to the hollow air supply box and the other end fixedly connected to the arc-shaped plate.

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