Forming cylinder of an additive manufacturing device with an adaptive dynamic sealing device

Abstract

The forming cylinder of an additive manufacturing device with an adaptive dynamic sealing device provided by the present invention includes a cylinder body, a piston platform driving mechanism, a sealing tape pressing and reversing device, a piston platform installation top adjustment frame, a piston platform and a sealing tape. The piston platform driving mechanism is arranged outside the cylinder body, and the sealing tape pressing and reversing device, the piston platform installation top adjustment frame and the piston platform are respectively arranged inside the cylinder body from bottom to top. The piston platform installation top adjustment frame is arranged on the sealing tape pressing and reversing device, and the piston platform is arranged on the piston platform installation top adjustment frame. A communication hole is arranged on the side wall of the cylinder body. One end of the sealing tape pressing and reversing device penetrates through the communication hole and is connected to the piston platform driving mechanism. The lower end of the sealing tape is fixedly connected to the cylinder body, and the upper end sequentially passes through the gaps between the sealing tape pressing and reversing device, the piston platform installation top adjustment frame, the piston platform and the cylinder body and is connected to the cylinder body; effectively avoiding the leakage of powder along the forming cylinder wall and the movement channel of the piston platform.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing equipment, and specifically to a forming cylinder of an additive manufacturing equipment with an adaptive dynamic sealing device. Background Art

[0002] In the field of additive manufacturing rapid prototyping technology, whether it is selective laser sintering forming, selective laser melting forming or binder jetting forming, the forming material is generally granular powder material. Then, when the piston platform moves inside the forming cylinder, the problem of powder sealing will be involved. As the forming area becomes larger and larger, the difficulty of sealing will also increase accordingly.

[0003] When the piston platform adopts bottom coaxial drive, the four walls of the forming cylinder body are in a continuous closed state, and the powder sealing difficulty of the piston platform is relatively low, and the sealing effect is also easy to ensure; with the increase of the forming area and the forming height, considering the preparation of conventional materials of the forming cylinder body, manufacturing cost and the structural dimensions of the forming cylinder, etc., the driving mode of the piston platform generally adopts two-side parallel drive, but the parallel drive will cause the four sides of the forming cylinder body not to be completely closed, and the sealing difficulty will also increase greatly. Summary of the Invention

[0004] Aiming at the above problems existing in the prior art, a forming cylinder of an additive manufacturing equipment with an adaptive dynamic sealing device provided by the present invention has the advantages of convenient disassembly, compact structure, convenient processing, etc., and can effectively avoid the problem of powder leakage along the inner wall of the forming cylinder and the movement channel of the piston platform.

[0005] To achieve the above invention purpose, the technical solution adopted by the present invention is as follows:

[0006] A forming cylinder of an additive manufacturing equipment with an adaptive dynamic sealing device, including a cylinder body, a piston platform driving mechanism, a sealing belt pressing and reversing device, a piston platform installation top adjustment frame, a piston platform and a sealing belt,

[0007] The piston platform driving mechanism is arranged outside the cylinder body, the sealing belt pressing and reversing device, the piston platform installation top adjustment frame and the piston platform are respectively arranged inside the cylinder body from bottom to top, the piston platform installation top adjustment frame is arranged on the sealing belt pressing and reversing device, the piston platform is arranged on the piston platform installation top adjustment frame, a communication hole is arranged on the side wall of the cylinder body, one end of the sealing belt pressing and reversing device penetrates through the communication hole and is connected with the piston platform driving mechanism, and the piston platform driving mechanism drives the piston platform through the sealing belt pressing and reversing device and the piston platform installation top adjustment frame.

[0008] The lower end of the sealing belt is fixedly connected to the cylinder block, and the upper end sequentially passes through the gaps between the sealing belt close contact commutation device, the piston platform mounting top adjustment bracket and the piston platform and the cylinder block and is connected to the cylinder block.

[0009] In one embodiment, the sealing belt close contact commutation device includes a base, a close contact shaft and a commutation shaft. The base includes a connecting portion and a working portion. One end of the connecting portion penetrates through the communication hole in the cylinder block and is connected to the piston platform driving mechanism, and the other end is connected to the working portion. A rotating shaft mounting hole is provided on the working portion. The close contact shaft and the commutation shaft are respectively rotatably arranged in the rotating shaft mounting hole from top to bottom, and the commutation shaft is located inside the close contact shaft. The outer side of the close contact shaft and the inner side of the commutation shaft are respectively in contact with the sealing belt.

[0010] In one embodiment, the close contact shaft and the commutation shaft are arranged parallel to each other.

[0011] In one embodiment, the outer surfaces of the close contact shaft and the commutation shaft are respectively coated with plastic.

[0012] In one embodiment, the close contact shaft and the commutation shaft are respectively rotatably connected to the side wall of the rotating shaft mounting hole through high-precision bearings.

[0013] In one embodiment, a protrusion is provided on the inner side of the lower end of the working portion, and the piston platform mounting top adjustment bracket is arranged above the protrusion.

[0014] In one embodiment, a sealing belt through hole is provided on the protrusion, and the sealing belt is inserted into the sealing belt through hole.

[0015] In one embodiment, a transition plate is further provided between the piston platform mounting top adjustment bracket and the protrusion, and the lower end of the outer side wall of the transition plate is chamfered.

[0016] In one embodiment, it further includes a sealing belt pressing plate and a sealing belt tensioning device. The upper end of the sealing belt is connected to the cylinder block through the sealing belt pressing plate, and the lower end of the sealing belt is connected to the cylinder block through the sealing belt tensioning device.

[0017] The sealing belt tensioning device includes a tensioning seat, a clamping plate, a spring, a flat washer and a screw. The clamping plate is arranged on the tensioning seat. The lower end of the sealing belt is clamped in the clamping plate. The threaded ends of at least two screws respectively penetrate through the tensioning seat and are screwed to the cylinder block. The flat washer and the spring are respectively sleeved on the screw and are located above the tensioning seat. The flat washer is located above the spring.

[0018] In one embodiment, it further includes a strip-shaped seal and a strip-shaped seal pressing plate. A plurality of seal mounting grooves are provided at the edge of the piston platform. The strip-shaped seal is disposed in the seal mounting groove and fixed by the strip-shaped seal pressing plate.

[0019] Compared with the prior art, the forming cylinder of the additive manufacturing equipment with an adaptive dynamic sealing device provided by the present invention provides a forming cylinder with convenient disassembly, compact structure, convenient processing, which can effectively avoid the problem of powder leakage along the inner wall of the forming cylinder and the movement channel of the piston platform, reduces the risk of affecting the forming effect or forming failure due to powder leakage during the forming process, and greatly improves the sealing reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of the present invention;

[0021] Figure 2 is a schematic structural diagram of the seal tape pressing device in the present invention;

[0022] Figure 3 is a schematic structural diagram of the seal tape tensioning device in the present invention;

[0023] Figure 4 is a schematic structural diagram of the piston platform driving mechanism in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0025] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means more than two, unless otherwise specifically defined.

[0026] In the present invention, unless otherwise clearly specified or limited, the terms "mounted", "connected", "coupled", "fixed", etc. shall be construed broadly. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly specified or limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0028] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without conflict, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0029] As Figures 1-4 shown, for the convenience of description, the orientation reference of "up", "down", "left", "right", "front", and "back" in the present invention is based on the Figure 1 orientation shown;

[0030] A forming cylinder of an additive manufacturing device with an adaptive dynamic sealing device, comprising a cylinder body 1, a piston platform driving mechanism 2, a sealing tape pressing and reversing device 3, a piston platform mounting and adjusting bracket 4, a piston platform 5, and a sealing tape 8.

[0031] The piston platform driving mechanism 2 is arranged outside the cylinder block 1. The sealing belt is tightly attached to the commutation device 3. The piston platform installation top adjustment bracket 4 and the piston platform 5 are respectively arranged inside the cylinder block 1 from bottom to top. The piston platform installation top adjustment bracket 4 is arranged on the sealing belt tightly attached commutation device 3, and the piston platform 5 is arranged on the piston platform installation top adjustment bracket 4. A communication hole 1-1 is arranged on the side wall of the cylinder block 1. One end of the sealing belt tightly attached commutation device 3 penetrates through the communication hole 1-1 and is connected to the piston platform driving mechanism 2. The piston platform driving mechanism 2 drives the piston platform 5 through the sealing belt tightly attached commutation device 3 and the piston platform installation top adjustment bracket 4. The piston platform installation top adjustment bracket 4 drives the piston platform 5 to lift and lower axially along the Z-axis by means of the piston platform driving mechanism 2 outside the forming cylinder 1;

[0032] The lower end of the sealing belt 8 is fixedly connected to the cylinder block 1, and the upper end sequentially passes through the gaps between the sealing belt tightly attached commutation device, the piston platform installation top adjustment bracket 4 and the piston platform 5 and the cylinder block 1 respectively and is connected to the cylinder block 1. The sealing belt 8 is mainly used to seal the gaps between the piston platform installation top adjustment bracket 4 and the piston platform 5 and the cylinder block 1 respectively, and can effectively avoid the problem of powder leakage along the inner wall of the forming cylinder and the movement channel of the piston platform.

[0033] In this embodiment, the sealing belt tightly attached commutation device 3 includes a base 3-1, a tight attachment shaft 3-2 and a commutation shaft 3-3. The base 3-1 includes a connection part 3-1-1 and a working part 3-1-2. One end of the connection part 3-1-1 penetrates through the communication hole 1-1 on the cylinder block 1 and is connected to the piston platform driving mechanism 2, and the other end is connected to the working part 3-1-2. A rotating shaft installation hole 3-1-2-1 is arranged on the working part 3-1-2. The tight attachment shaft 3-2 and the commutation shaft 3-3 are respectively rotatably arranged in the rotating shaft installation hole 3-1-2-1 from top to bottom, and the commutation shaft 3-3 is located inside the tight attachment shaft 3-2. Therefore, Figure 1 It can be seen that the tight attachment shaft 3-2 is arranged at the upper left part of the base 3-1, and its function is to make the sealing belt 8 closely fit the inner wall of the cylinder block 1. The commutation shaft 3-3 is arranged at the lower right part of the base 3-1, and its function is to make the sealing belt 8 commutate and reduce the wrap angle of the sealing belt 8 passing through the tight attachment shaft 3-2, and can also provide a more spacious installation space for the sealing belt tensioning device 10; The outer side of the tight attachment shaft 3-2 and the inner side of the commutation shaft 3-3 are respectively in contact with the sealing belt 8.

[0034] Among them, the piston platform driving mechanism 2 includes a mounting top adjustment plate 2-1, a screw jack 2-2, a support seat 2-3, a cross beam 2-4, a linear guide rail assembly 2-5, a motor seat 2-6, a motor 2-7 and a coupling 2-8. The mounting top adjustment plate 2-1 is arranged at the bottom outside the cylinder block 1. The screw jack 2-2 and the motor seat 2-6 are arranged on the mounting top adjustment plate 2-1. The motor 2-7 is arranged on the motor seat 2-6. The motor 2-7 is drivingly connected to the screw jack 2-2 through the coupling 2-8. The upper end of the screw jack 2-2 is connected to the top outside the cylinder block 1 through the support seat 2-3. The cross beam 2-4 is screwed on the screw of the screw jack 2-2. The linear guide rail assembly 2-5 includes a slide rail and a slider. The slide rails are longitudinally arranged on the outer side walls of the cylinder block 1 respectively. Sliders are respectively arranged on the inner sides of both ends of the cross beam 2-4. And the sliders at both ends of the cross beam 2-4 are slidably arranged on the slide rails correspondingly to enable the cross beam 2-4 to move up and down relative to the cylinder block 1. One end of the connecting part 3-1-1 penetrates through the communication hole 1-1 on the cylinder block 1 and is respectively connected to the inner side of the cross beam 2-4. Therefore, it can be realized that the piston platform driving mechanism 2 drives the piston platform 5 to move up and down along the Z-axis direction through the sealing belt pressing tightly against the commutation device 3 and the piston platform mounting top adjustment frame 4.

[0035] Preferably, in order to enable the sealing belt to better closely fit the inner wall of the cylinder block 1 and avoid unnecessary torsional deformation, the pressing shaft 3-2 and the commutation shaft 3-3 are designed to be parallel to each other.

[0036] Preferably, the outer surfaces of the pressing shaft 3-2 and the commutation shaft 3-3 are respectively coated with plastic to reduce the wear between the pressing shaft 3-2 and the commutation shaft 3-3 and the surface of the sealing belt 8.

[0037] Furthermore, the pressing shaft 3-2 and the commutation shaft 3-3 are respectively rotatably connected to the side walls of the rotating shaft mounting holes 3-1-2-1 through high-precision bearings. Specifically, bearing mounting holes are provided on the side walls of the rotating shaft mounting holes 3-1-2-1. The bearings are installed in the bearing mounting holes. The two ends of the pressing shaft 3-2 and the commutation shaft 3-3 are respectively inserted into the bearings inside the side walls of the rotating shaft mounting holes 3-1-2-1 correspondingly to realize the rotatable connection between the pressing shaft 3-2 and the commutation shaft 3-3 and the side walls of the rotating shaft mounting holes 3-1-2-1. Because high-precision bearings are adopted, the wear of the dynamic fitting surface between the pressing shaft 3-2 and the commutation shaft 3-3 and the sealing belt 8 is further reduced.

[0038] In this embodiment, a protrusion 3-1-3 is arranged on the inner side of the lower end of the working part 3-1-2. The piston platform mounting top adjustment frame 4 is arranged above the protrusion 3-1-3.

[0039] In this embodiment, a sealing belt through hole 3-1-3-1 is provided on the protrusion 3-1-3, and the sealing belt 8 is inserted into the sealing belt through hole 3-1-3-1 so as to facilitate the sealing belt 8 to be wrapped from the outer side of the reversing shaft 3-3 to the inner side of the clamping shaft 3-2, thereby realizing the sealing belt 8 to be tightly fitted to the inner wall of the cylinder body 1.

[0040] Furthermore, a transition plate 11 is provided between the piston platform mounting top adjustment frame 4 and the protrusion 3-1-3, and the lower end of the outer wall of the transition plate 11 is chamfered to facilitate the sealing belt 8 to pass through the sealing belt through hole 3-1-3-1 from bottom to top.

[0041] In this embodiment, a sealing belt pressing plate 9 and a sealing belt tensioning device 10 are also included. The upper end of the sealing belt 8 is connected to the cylinder body through the sealing belt pressing plate 9, and the lower end of the sealing belt 8 is connected to the cylinder body 1 through the sealing belt tensioning device 10.

[0042] Among them, the sealing belt tensioning device 10 includes a tensioning seat 10-1, a clamping plate 10-2, a spring 10-3, a flat washer 10-4 and a screw 10-5. The clamping plate 10-2 is arranged on the tensioning seat 10-1, and the lower end of the sealing belt 8 is clamped in the clamping plate 10-2. The threaded ends of at least two screws 10-5 respectively penetrate the tensioning seat 10-1 and are screwed to the cylinder body 1. Preferably, the two screws 10-5 are symmetrically arranged at both ends of the tensioning seat 10-1, which is conducive to the later rotation of the screws 10-5 and thus uniformly adjusting the tension on both sides of the sealing belt 8; the flat washer 10-4 and the spring 10-3 are respectively mounted on the screws. The flat washer 10-4 is located above the spring 10-3, so that the upper and lower positions of the entire clamping plate 10-2 and the tensioning seat 10-1 can be adjusted by rotating the screw 10-5, thereby adjusting the tension of the sealing belt 8. Because the sealing belt 8 may have a certain plastic deformation and become longer during the long-term lifting and lowering of the piston platform 5, the spring 10-3 arranged here can compensate to a certain extent for the problem that the sealing belt 8 is loose due to plastic deformation and cannot fit tightly with the cylinder body 1, resulting in poor sealing and leakage of forming powder.

[0043] In this embodiment, it also includes a strip seal 6 and a strip seal pressure plate 7. Several seal installation grooves are arranged at the edge of the piston platform 5. The strip seal 6 is arranged in the seal installation groove, and the strip seal 6 is fixed in the seal installation groove by the strip seal pressure plate 7 connected to the cylinder body 1. The strip seal 6 fits tightly against the inner cylinder wall of the cylinder body 1 to achieve effective sealing.

[0044] Performance Testing:

[0045] Sealing Solution (I) Test Record

[0046] Sealing tape material selection: SUS410 strip material with a thickness of 0.25 mm and a width of 80 mm

[0047] Required sealing channel width: 60 mm

[0048] Test results: The hardness of the sealing tape is too high. After passing through the pressing shaft and the reversing shaft, local hardening of the strip occurs, resulting in an unsatisfactory fitting state with the inner wall of the forming cylinder and powder leakage.

[0049] Test record of sealing solution (two)

[0050] Sealing tape material selection: SUS410 strip material with a thickness of 0.2 mm and a width of 80 mm

[0051] Required sealing channel width: 60 mm

[0052] Test results: The hardness of the sealing tape is reduced. After passing through the pressing shaft and the reversing shaft, the local hardening of the strip is greatly reduced, the fitting effect with the inner wall of the forming cylinder is greatly improved, and the powder leakage phenomenon is basically eliminated.

[0053] Test record of sealing solution (three)

[0054] Sealing tape material selection: SUS410 strip material with a thickness of 0.15 mm and a width of 100 mm

[0055] Required sealing channel width: 60 mm

[0056] Test results: The hardness of the sealing tape is low. After passing through the pressing shaft and the reversing shaft, there is basically no local hardening of the strip, the fitting effect with the inner wall of the forming cylinder is excellent, and there is no powder leakage phenomenon.

[0057] Summary: The sealing tape material can be reasonably selected according to the actual working conditions. The above test schemes are only one kind of working condition environment used. Among the above three test schemes, as the thickness of the sealing tape becomes thinner, the flexibility of the sealing tape increases, the strength and sealing life decrease, but the sealing effect is excellent, and the sealing tape needs to be replaced regularly. After the sealing tape becomes thinner to a certain extent, its width needs to be increased to increase the fitting surface area where the sealing tape coincides with the cylinder wall, and strengthen the sealing tape to withstand the powder pressure in the forming cylinder at the driving channel part.

[0058] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as these combinations of technical features do not conflict, they should all be considered as the scope recorded in this specification.

[0059] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be subject to the appended claims.

Claims

1. The forming cylinder of an additive manufacturing device with an adaptive dynamic sealing device, characterized in that, It includes a cylinder block, a piston platform driving mechanism, a sealing strip pressing and reversing device, a piston platform installation top adjusting frame, a piston platform, a sealing strip, a sealing strip pressing plate and a sealing strip tensioning device; The piston platform driving mechanism is arranged outside the cylinder block, and the sealing strip pressing and reversing device, the piston platform installation top adjusting frame and the piston platform are respectively arranged inside the cylinder block from bottom to top. The piston platform installation top adjusting frame is arranged on the sealing strip pressing and reversing device, the piston platform is arranged on the piston platform installation top adjusting frame, a communication hole is arranged on the side wall of the cylinder block, one end of the sealing strip pressing and reversing device penetrates through the communication hole and is connected with the piston platform driving mechanism, and the piston platform driving mechanism drives the piston platform through the sealing strip pressing and reversing device and the piston platform installation top adjusting frame. The lower end of the sealing strip is fixedly connected with the cylinder block, and the upper end sequentially passes through the gaps between the sealing strip pressing and reversing device, the piston platform installation top adjusting frame and the piston platform and the cylinder block and is connected with the cylinder block; the sealing strip pressing and reversing device includes a base, a pressing shaft and a reversing shaft. The base includes a connecting part and a working part. One end of the connecting part penetrates through the communication hole on the cylinder block and is connected with the piston platform driving mechanism, and the other end is connected with the working part. A rotating shaft installation hole is arranged on the working part. The pressing shaft and the reversing shaft are respectively rotatably arranged in the rotating shaft installation hole from top to bottom, and the reversing shaft is located inside the pressing shaft. The outer side of the pressing shaft and the inner side of the reversing shaft are respectively in contact with the sealing strip. The upper end of the sealing strip is connected with the cylinder block through the sealing strip pressing plate, and the lower end of the sealing strip is connected with the cylinder block through the sealing strip tensioning device. The sealing strip tensioning device includes a tensioning seat, a clamping plate, a spring, a flat washer and a screw. The clamping plate is arranged on the tensioning seat. The lower end of the sealing strip is clamped in the clamping plate. The threaded ends of at least two screws respectively penetrate through the tensioning seat and are screwed with the cylinder block. The flat washer and the spring are respectively sleeved on the screw and are located above the tensioning seat. The flat washer is located above the spring.

2. The forming cylinder of an additive manufacturing device with an adaptive dynamic sealing device according to claim 1, wherein The pressing shaft and the reversing shaft are arranged parallel to each other.

3. The forming cylinder of an additive manufacturing device with an adaptive dynamic sealing device according to claim 2, characterized in that, The outer surfaces of the pressing shaft and the reversing shaft are respectively coated with plastic.

4. The forming cylinder of an additive manufacturing device with an adaptive dynamic sealing device according to claim 3, characterized in that, The pressing shaft and the reversing shaft are respectively rotatably connected with the side wall of the rotating shaft installation hole through high-precision bearings.

5. The forming cylinder of an additive manufacturing device with an adaptive dynamic sealing device according to claim 1, characterized in that, A protrusion is arranged on the inner side of the lower end of the working part, and the piston platform installation top adjusting frame is arranged above the protrusion.

6. The forming cylinder of an additive manufacturing device with an adaptive dynamic sealing device according to claim 5, characterized in that, A sealing strip through hole is arranged on the protrusion, and the sealing strip is inserted into the sealing strip through hole.

7. The forming cylinder of an additive manufacturing device with an adaptive dynamic sealing device according to claim 6, characterized in that, A transition plate is further arranged between the piston platform installation top adjusting frame and the protrusion, and the lower end of the outer side wall of the transition plate is chamfered.

8. The forming cylinder of an additive manufacturing device with an adaptive dynamic sealing device according to claim 1, characterized in that, It further includes a strip-shaped sealing member and a strip-shaped sealing member pressing plate. Several sealing member installation grooves are arranged at the edge of the piston platform. The strip-shaped sealing member is arranged in the sealing member installation groove and is fixed through the strip-shaped sealing member pressing plate.

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