Z-axis lifting mechanism

Abstract

The utility model belongs to the technical field of 3D printing, and relates to a Z-axis lifting mechanism which comprises a steel belt type movement mechanism arranged on the side portion of a forming cylinder and a bearing mechanism arranged in the forming cylinder. A through hole or a through groove is formed in the top of the side wall of the forming cylinder; the steel belt type movement mechanism penetrates through the through hole or the through groove, then is connected with the bearing mechanism and drives the bearing mechanism to freely ascend and descend along the Z axis of the forming cylinder. According to the Z-axis lifting mechanism, the height of the Z axis is effectively reduced, and the sealing performance requirement of the Z axis can be met.

Description

Technical Field

[0001] The utility model belongs to the technical field of 3D printing, and relates to a Z-axis lifting mechanism, in particular to a Z-axis lifting mechanism for SLM equipment. Background Art

[0002] Metal 3D printing technology is the common name for metal additive manufacturing technology. It refers to a technology that uses powdered or filamentary metal materials to construct metal parts by printing layer by layer based on the discrete-accumulation principle, three-dimensional digital model files and program commands. According to the different printing methods and printing materials, 3D printers can be divided into different types, and SLM (selective laser melting) is one of them. In SLM equipment, the Z-axis lifting mechanism is a relatively important component. At present, there are two main arrangements for the lifting mechanism of the forming cylinder. One is to arrange it directly below the forming platform, and the lifting action is assisted by the guide screw and guide rod; the other is to arrange it on one or both sides of the outer wall of the forming cylinder, and connect the bracket supporting the piston to the cylinder through the long strip hole on the side of the cylinder, and use the adjustable roller to tighten the steel belt to provide sealing for the lifting action. The first arrangement requires at least twice the stroke height in the vertical direction to ensure the effective stroke of the equipment. This method increases the overall height of the equipment, which will cause inconvenience in the assembly, maintenance and transportation of the equipment on large-size equipment. The second arrangement effectively solves the problem of excessive height in the vertical direction, but the steel belt is too thin. Under the pressure of the printing material on the steel belt and the repeated lifting and lowering of the piston, the steel belt causes fatigue deformation, poor sealing effect, and easy to cause powder leakage, resulting in the inability to perform printing work normally. Utility Model Content

[0003] In order to solve the above technical problems existing in the background technology, the utility model provides a Z-axis lifting mechanism which can effectively reduce the height of the Z-axis and meet the sealing requirements of the Z-axis.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A Z-axis lifting mechanism, characterized in that: the Z-axis lifting mechanism includes a steel belt type motion mechanism arranged on the side of a forming cylinder and a bearing mechanism arranged inside the forming cylinder; a through hole or a through groove is arranged on the top of the side wall of the forming cylinder; the steel belt type motion mechanism passes through the through hole or the through groove and is connected to the bearing mechanism and drives the bearing mechanism to rise and fall freely along the Z-axis of the forming cylinder.

[0006] The above-mentioned steel belt type motion mechanism is arranged on one side or both sides of the forming cylinder.

[0007] The above-mentioned steel belt motion mechanism includes a steel belt, a driving member and a pulley block; one end of the steel belt is connected to the bearing mechanism, and the other end passes through the through hole or through groove and is fixed on the bearing mechanism after being wound around the pulley block; the driving member is connected to the steel belt and drives the bearing mechanism to rise and fall freely along the Z axis of the forming cylinder through the steel belt.

[0008] The above-mentioned driving component includes a driving motor, a synchronous belt, a screw and a fixed frame; the axial direction of the screw is parallel to the Z axis of the forming cylinder; the driving motor drives the screw to rotate through the synchronous belt; a guide rail slider assembly parallel to the axial direction of the screw is provided on the side wall of the forming cylinder; one end of the fixed frame is placed in the guide rail slider assembly and moves freely along the axial direction of the guide rail slider assembly, and the other end cooperates with the screw for spiral rotation; the fixed frame drives the bearing mechanism to rise and fall freely along the Z axis of the forming cylinder through a steel belt.

[0009] The guide rail and slider assembly comprises a guide rail arranged on the side wall of the forming cylinder and a slider placed in the guide rail and freely moving along the axial direction of the guide rail; the axial direction of the guide rail is parallel to the axial direction of the lead screw; one end of the fixing frame is connected to the slider.

[0010] The steel belt motion mechanism further comprises a grating ruler arranged on the side wall of the forming cylinder; the reading head of the grating ruler is arranged on a fixing frame.

[0011] The above-mentioned steel belt type motion mechanism also includes a steel belt tensioning mechanism which is arranged at the bottom of the bearing mechanism and acts on the steel belt;

[0012] When the steel belt type motion mechanism is arranged on one side of the forming cylinder, the steel belt tensioning mechanism comprises a fixed seat, a length adjustment rod, a connecting seat and a tensioning wheel; the fixed seat is arranged at the bottom of the bearing mechanism; a groove is arranged on the fixed seat; the connecting seat is placed in the groove and moves along the axial direction of the groove; the axial direction of the length adjustment rod is parallel to the axial direction of the groove; one end of the length adjustment rod is fixed on the fixed seat, and the other end is connected to the tensioning wheel through the connecting seat; the steel belt is wound around the tensioning wheel;

[0013] When the steel belt type motion mechanism is arranged on both sides of the forming cylinder, the steel belt tensioning mechanism includes a length adjustment rod, a first steel belt tensioning mechanism and a second steel belt tensioning mechanism; the structure of the first steel belt tensioning mechanism is exactly the same as that of the second steel belt tensioning mechanism; the first steel belt tensioning mechanism and the second steel belt tensioning mechanism are arranged in a mirror image; the first steel belt tensioning mechanism includes a fixed seat, a connecting seat and a tensioning wheel; the fixed seat is arranged at the bottom of the bearing mechanism; a groove is arranged on the fixed seat; the connecting seat is placed in the groove and moves along the axial direction of the groove; the axial direction of the length adjustment rod is parallel to the axial direction of the groove; one end of the length adjustment rod is connected to the tensioning wheel of the first steel belt tensioning mechanism through the connecting seat of the first steel belt tensioning mechanism, and the other end is connected to the tensioning wheel of the second steel belt tensioning mechanism through the connecting seat of the second steel belt tensioning mechanism; the steel belt is wound around the tensioning wheel.

[0014] The above-mentioned bearing mechanism includes a substrate, a heating water-cooling plate, a sealing plate and a platform substrate stacked and laid in sequence from top to bottom; the steel belt type motion mechanism passes through the through hole or through groove and is connected to the substrate, the heating water-cooling plate, the sealing plate and / or the platform substrate.

[0015] The above-mentioned Z-axis lifting mechanism also includes a sealing mechanism; the sealing mechanism includes a steel belt sealing assembly and an internal cylinder seal; the steel belt sealing assembly is placed in a through hole or a through groove and is located between the steel belt motion mechanism and the forming cylinder; the internal cylinder seal is placed between the forming cylinder and the sealing plate.

[0016] The above-mentioned steel belt sealing assembly includes a first seal and a second seal; the structure of the first seal and the structure of the second seal are the same or unequal; the first seal, the second seal and the internal seal of the cylinder body are sealing structures such as sealing rings, O-rings, felt, inflatable sealing rings and / or rubber strips.

[0017] The advantages of the utility model are:

[0018] The utility model provides a Z-axis lifting mechanism, which includes a steel belt type motion mechanism arranged on the side of the forming cylinder and a bearing mechanism arranged inside the forming cylinder; a through hole or a through groove is arranged on the top of the side wall of the forming cylinder; the steel belt type motion mechanism passes through the through hole or the through groove and is connected to the bearing mechanism and drives the bearing mechanism to freely lift and lower along the Z axis of the forming cylinder. The utility model directly avoids the high height of the piston Z-axis lifting structure in the prior art through steel belt transmission, thereby reducing the cost of the equipment; at the same time, through the sealing mechanism arranged between the steel belt type motion mechanism and the forming cylinder and between the forming cylinder and the bearing mechanism, the problem of poor powder sealing effect of the steel belt sealing of the cantilever Z-axis lifting structure in the prior art is overcome. In short, the Z-axis lifting mechanism provided by the utility model can effectively reduce the height of the Z axis, while also meeting the sealing requirements of the Z axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the Z-axis lifting mechanism provided by the utility model;

[0020] Figure 2 It is a cross-sectional structural schematic diagram of the Z-axis lifting mechanism provided by the utility model;

[0021] in:

[0022] 1-forming cylinder; 2-steel belt sealing assembly; 201-first sealing member; 202-second sealing member; 3-pulley block; 4-grating scale; 5-lead screw; 6-fixed frame; 7-steel belt; 8-guide rail slider assembly; 9-driving motor; 10-synchronous belt; 11-steel belt tensioning mechanism; 12-platform base plate; 13-sealing plate; 14-cylinder internal sealing member; 15-heating water cooling plate; 16-substrate. DETAILED DESCRIPTION

[0023] The utility model provides a Z-axis lifting mechanism, which includes a steel belt type motion mechanism arranged on the side of the forming cylinder 1 and a bearing mechanism arranged inside the forming cylinder 1; a through hole or a through groove is arranged on the top of the side wall of the forming cylinder 1; the steel belt type motion mechanism passes through the through hole or the through groove and is connected to the bearing mechanism and drives the bearing mechanism to freely lift and lower along the Z axis of the forming cylinder 1. The core idea of ​​the utility model is to drive the bearing mechanism to freely lift and lower along the Z axis of the forming cylinder 1 by setting a through hole or a through groove on the top of the side wall of the forming cylinder 1, and by passing the steel belt type motion mechanism through the through hole or the through groove, so as to directly avoid the high height of the piston Z axis lifting structure in the prior art and reduce the cost of the equipment.

[0024] Specifically, the Z-axis lifting mechanism provided by the present invention is presented in the following structure or manner:

[0025] The steel belt motion mechanism is arranged on one side or both sides of the forming cylinder 1. Regardless of being on one side or both sides, the structure of the steel belt motion mechanism is the same. Exemplarily, the steel belt motion mechanism includes a steel belt 7, a driving member and a pulley block 3; the steel belt 7 is connected to the supporting mechanism and is wound around the pulley block 3; the driving member is connected to the steel belt 7 and drives the supporting mechanism to rise and fall freely along the Z axis of the forming cylinder 1 through the steel belt 7; the sealing mechanism is placed between the steel belt 7 and the forming cylinder 1 and between the forming cylinder 1 and the supporting mechanism. Exemplarily, the pulley block 3 can be respectively arranged at the top and bottom of the side of the forming cylinder 1, and of course, it can also be arranged at other parts of the side of the forming cylinder 1. Figure 2For example, the pulley group 3 includes a top pulley group and a bottom pulley group. The top pulley group is located at the top position of the side of the forming cylinder 1, parallel to the through hole or the through groove, and the number is set as one group for reference (of course, multiple groups can also be used); the bottom pulley group is located at the bottom position of the side of the forming cylinder 1, opposite to the position of the top pulley group, but considering that there is no through hole or through groove at the bottom of the side of the forming cylinder 1, the bottom pulley group is set as two parallel groups (of course, one group can also be used, and the specific number is not limited). The setting of the pulley group is intended to facilitate the smooth passage of the steel belt 7.

[0026] See also Figure 1 as well as Figure 2 , exemplarily, the driving parts used in the utility model include a driving motor 9, a synchronous belt 10, a screw 5 and a fixed frame 6; the axial direction of the screw 5 is parallel to the Z axis of the forming cylinder 1; the driving motor 9 drives the screw 5 to rotate through the synchronous belt 10; a guide rail slider assembly 8 parallel to the axial direction of the screw 5 is provided on the side wall of the forming cylinder 1; one end of the fixed frame 6 is placed in the guide rail slider assembly 8 and moves freely along the axial direction of the guide rail slider assembly 8, and the other end is threadedly matched with the screw 5; the fixed frame 6 is connected to the steel belt 7 (the connection method is the existing conventional method, and the utility model does not impose special restrictions on the connection method. Exemplarily, the fixed frame 6 is connected to the steel belt 7 by clamping; or an opening is set on the steel belt 7, and the fixed frame 6 extends into the opening on the steel belt 7. No matter which connection method is used, as long as it can ensure that the fixed frame 6 and the steel belt 7 move synchronously), and the steel belt 7 drives the bearing mechanism to rise and fall freely along the Z axis of the forming cylinder 1. The guide rail and slider assembly 8 includes a guide rail arranged on the side wall of the forming cylinder 1 and a slider placed in the guide rail and freely moving along the axial direction of the guide rail; the axial direction of the guide rail is parallel to the axial direction of the lead screw 5; one end of the fixed frame 6 is connected to the slider. For example, Figure 1 as well as Figure 2 As shown, this is the preferred or more preferred method adopted by the utility model, namely: the steel belt motion mechanism is arranged on both sides of the forming cylinder 1. Through the simultaneous action of the steel belt motion mechanisms on both sides, the bearing mechanism can be made to move along the Z axis inside the forming cylinder 1 in a more balanced manner, and the control is more precise.

[0027] When the steel belt type motion mechanism used in the utility model is working, firstly one end of the steel belt 7 is passed through and fixed on the bearing mechanism, and the other end is passed through and fixed on the fixed frame 6 after passing through the top pulley block 3, and then is passed back from the bottom pulley block 3 and fixed on the bearing mechanism to form a transmission chain. After the driving motor 9 is turned on, the driving motor 9 is connected to the lead screw 5 through the synchronous belt 10 and drives the lead screw 5 to rotate, and the lead screw 5 drives the steel belt 7 to move through the fixed frame 6, the guide rail slider assembly 8 is fixed on the outer wall of the forming cylinder 1, and the slider of the guide rail slider assembly 8 is fixedly connected to the fixed frame 6, and the lead screw 5 pushes the fixed frame 6 to slide on the guide rail slider assembly 8, and finally the movement of the steel belt 7 is converted into the bearing mechanism moving up and down along the axial direction (i.e., Z axis) of the forming cylinder 1 inside the forming cylinder 1. It should be noted that any slight changes in the number of steel belts, width, installation method (such as passing through the upper fixation, one steel belt on one side with four steel belts fixed in a small loop, changes in the tensioning mechanism, changes in the guide wheel structure, single-motor synchronous belt drive, dual motors directly connected to the screw through a coupling, etc.) are considered within the protection range as long as they do not leave the belt drive (such as a steel chain composed of steel wire, a wide steel belt, a composite material belt, etc.).

[0028] The steel belt motion mechanism also includes a grating ruler 4 arranged on the side wall of the forming cylinder 1; the reading head of the grating ruler 4 is arranged on the fixed frame 6. When the driving motor 9 drives the fixed frame 6 to move through the lead screw 5, the position of the fixed frame 6 is detected by the reading head of the grating ruler 4 to realize the closed-loop control of the motor.

[0029] The steel belt motion mechanism also includes a steel belt tensioning mechanism 11 which is arranged at the bottom of the bearing mechanism and acts on the steel belt 7. The steel belt tensioning mechanism 11 can be arranged according to the setting of the steel belt motion mechanism. Exemplarily, when the steel belt motion mechanism is arranged on one side of the forming cylinder 1, the steel belt tensioning mechanism 11 includes a fixed seat, a length adjustment rod, a connecting seat and a tensioning wheel; the fixed seat is arranged at the bottom of the bearing mechanism; a groove is arranged on the fixed seat; the connecting seat is placed in the groove and moves along the axial direction of the groove; the axial direction of the length adjustment rod is parallel to the axial direction of the groove; one end of the length adjustment rod is fixed on the fixed seat, and the other end is connected to the tensioning wheel through the connecting seat; the steel belt 7 is wound on the tensioning wheel. The force sensor on the length adjustment rod of the steel belt tensioning mechanism 11 (exemplarily, a lead screw can generally be used) is used to detect the force change during the forming process and compensate for the Z-axis precision control. See. Figure 2When the steel belt motion mechanism is arranged on both sides of the forming cylinder 1, the steel belt tensioning mechanism 11 includes a length adjustment rod, a first steel belt tensioning mechanism and a second steel belt tensioning mechanism; the structure of the first steel belt tensioning mechanism is exactly the same as that of the second steel belt tensioning mechanism; the first steel belt tensioning mechanism and the second steel belt tensioning mechanism are arranged in a mirror image; the first steel belt tensioning mechanism includes a fixed seat, a connecting seat and a tensioning wheel; the fixed seat is arranged at the bottom of the bearing mechanism; a groove is arranged on the fixed seat; the connecting seat is placed in the groove and moves along the axial direction of the groove; the axial direction of the length adjustment rod is parallel to the axial direction of the groove; one end of the length adjustment rod is connected to the tensioning wheel of the first steel belt tensioning mechanism through the connecting seat of the first steel belt tensioning mechanism, and the other end is connected to the tensioning wheel of the second steel belt tensioning mechanism through the connecting seat of the second steel belt tensioning mechanism; the steel belt 7 is wound around the tensioning wheel.

[0030] See also Figure 1 as well as Figure 2 The Z-axis lifting mechanism provided by the utility model also includes a sealing mechanism; the sealing mechanism includes a steel belt sealing assembly 2 and a cylinder internal seal 14; the steel belt sealing assembly 2 is placed in a through hole or a through groove and is between the steel belt type motion mechanism and the forming cylinder 1; the cylinder internal seal 14 is placed between the forming cylinder 1 and the bearing mechanism. The utility model overcomes the problem of poor powder sealing effect of the steel belt seal using the cantilever Z-axis lifting structure in the prior art by setting a sealing mechanism between the steel belt type motion mechanism and the forming cylinder 1 and between the forming cylinder and the bearing mechanism. Moreover, the utility model is provided with a through hole or a through groove at the top of the side wall of the forming cylinder 1, which is completely different from the through hole opened on the side wall of the forming cylinder 1 along the height of the forming cylinder 1 in the prior art. Under the premise of reducing the difficulty of opening the hole, it undoubtedly also improves the sealing performance. The sealing difficulty of a small-area through hole is much lower than that of a large-area through hole. The steel belt sealing assembly 2 includes a first seal 201 and a second seal 202; the first seal 201 and the second seal 202 seal the upper and lower surfaces of the steel belt 7 passing through the top of the forming cylinder 1 (i.e., used to seal the gap between the steel belt 7 and the forming cylinder 1, especially the gap between the steel belt 7 and the top of the forming cylinder 1). The structure of the first seal 201 and the structure of the second seal 202 are the same or different; illustratively, the first seal 201, the second seal 202 and the cylinder internal seal 14 can all be sealing structures such as sealing rings, O-rings, felt, inflatable sealing rings and / or rubber strips.

[0031] Exemplarily, the supporting mechanism adopted by the present invention includes a substrate 16, a heating and water-cooling plate 15, a sealing plate 13 and a platform substrate 12 which are stacked and laid in sequence from top to bottom; a sealing ring serving as an internal seal 14 of the cylinder body is placed between the forming cylinder 1 and the sealing plate 13, and is used to seal the gap between the forming cylinder 1 and the sealing plate 13, that is, to seal the Z axis; both ends of the steel belt 7 are fixed between the substrate 16 and the platform substrate 12, and exemplary, one end of the steel belt 7 is fixed between the sealing plate 13 and the heating and water-cooling plate 15, and the other end is fixed between the sealing plate 13 and the platform substrate 12.

Claims

1. A Z-axis lifting mechanism, characterized in that: The Z-axis lifting mechanism comprises a steel belt type moving mechanism arranged on the side of the forming cylinder (1) and a bearing mechanism arranged inside the forming cylinder (1); a through hole or a through groove is arranged on the top of the side wall of the forming cylinder (1); the steel belt type moving mechanism passes through the through hole or the through groove and is connected to the bearing mechanism, and drives the bearing mechanism to freely lift and lower along the Z-axis of the forming cylinder (1).

2. The Z-axis lifting mechanism according to claim 1, characterized in that: The steel belt type motion mechanism is arranged on one side or both sides of the forming cylinder (1).

3. The Z-axis lifting mechanism according to claim 2, characterized in that: The steel belt type motion mechanism comprises a steel belt (7), a driving member and a pulley block (3); one end of the steel belt (7) is connected to the bearing mechanism, and the other end passes through a through hole or a through groove and is wound around the pulley block (3) and then fixed on the bearing mechanism; the driving member is connected to the steel belt (7) and drives the bearing mechanism to rise and fall freely along the Z axis of the forming cylinder (1) through the steel belt (7).

4. The Z-axis lifting mechanism according to claim 3, characterized in that: The driving member comprises a driving motor (9), a synchronous belt (10), a lead screw (5) and a fixing frame (6); the axial direction of the lead screw (5) is parallel to the Z axis of the forming cylinder (1); the driving motor (9) drives the lead screw (5) to rotate through the synchronous belt (10); a guide rail slider assembly (8) parallel to the axial direction of the lead screw (5) is arranged on the side wall of the forming cylinder (1); one end of the fixing frame (6) is placed in the guide rail slider assembly (8) and moves freely along the axial direction of the guide rail slider assembly (8), and the other end is spirally rotated with the lead screw (5); the fixing frame (6) drives the bearing mechanism to freely rise and fall along the Z axis of the forming cylinder (1) through the steel belt (7).

5. The Z-axis lifting mechanism according to claim 4, characterized in that: The guide rail and slider assembly (8) comprises a guide rail arranged on the side wall of the forming cylinder (1) and a slider placed in the guide rail and freely moving along the axial direction of the guide rail; the axial direction of the guide rail is parallel to the axial direction of the lead screw (5); one end of the fixed frame (6) is connected to the slider.

6. The Z-axis lifting mechanism according to claim 5, characterized in that: The steel belt type motion mechanism further comprises a grating ruler (4) arranged on the side wall of the forming cylinder (1); the reading head of the grating ruler (4) is arranged on a fixing frame (6).

7. The Z-axis lifting mechanism according to claim 6, characterized in that: The steel belt type motion mechanism further comprises a steel belt tensioning mechanism (11) which is arranged at the bottom of the bearing mechanism and acts on the steel belt (7); When the steel belt type motion mechanism is arranged on one side of the forming cylinder (1), the steel belt tensioning mechanism (11) comprises a fixed seat, a length adjustment rod, a connecting seat and a tensioning wheel; the fixed seat is arranged at the bottom of the bearing mechanism; a groove is arranged on the fixed seat; the connecting seat is placed in the groove and moves along the axial direction of the groove; the axial direction of the length adjustment rod is parallel to the axial direction of the groove; one end of the length adjustment rod is fixed on the fixed seat, and the other end is connected to the tensioning wheel through the connecting seat; the steel belt (7) is wound around the tensioning wheel; When the steel belt type motion mechanism is arranged on both sides of the forming cylinder (1), the steel belt tensioning mechanism (11) comprises a length adjustment rod, a first steel belt tensioning mechanism and a second steel belt tensioning mechanism; the structure of the first steel belt tensioning mechanism is completely the same as that of the second steel belt tensioning mechanism; the first steel belt tensioning mechanism and the second steel belt tensioning mechanism are arranged in a mirror image; the first steel belt tensioning mechanism comprises a fixing seat, a connecting seat and a tensioning wheel; the fixing seat is arranged at the bottom of the bearing mechanism; a groove is arranged on the fixing seat; the connecting seat is placed in the groove and moves along the axial direction of the groove; the axial direction of the length adjustment rod is parallel to the axial direction of the groove; one end of the length adjustment rod is connected to the tensioning wheel of the first steel belt tensioning mechanism through the connecting seat of the first steel belt tensioning mechanism, and the other end is connected to the tensioning wheel of the second steel belt tensioning mechanism through the connecting seat of the second steel belt tensioning mechanism; the steel belt (7) is wound around the tensioning wheel.

8. The Z-axis lifting mechanism according to any one of claims 1 to 7, characterized in that: The bearing mechanism comprises a base material (16), a heating water-cooling plate (15), a sealing plate (13) and a platform base plate (12) which are stacked and laid in sequence from top to bottom; the steel belt type motion mechanism passes through the through hole or the through groove and is connected to the base material (16), the heating water-cooling plate (15), the sealing plate (13) and / or the platform base plate (12).

9. The Z-axis lifting mechanism according to claim 8, characterized in that: The Z-axis lifting mechanism also includes a sealing mechanism; the sealing mechanism includes a steel belt sealing component (2) and a cylinder internal sealing component (14); the steel belt sealing component (2) is placed in the through hole or through groove and is located between the steel belt motion mechanism and the forming cylinder (1); the cylinder internal sealing component (14) is placed between the forming cylinder (1) and the sealing plate (13).

10. The Z-axis lifting mechanism according to claim 9, characterized in that: The steel belt sealing assembly (2) comprises a first sealing member (201) and a second sealing member (202); the structure of the first sealing member (201) and the structure of the second sealing member (202) are the same or different; the first sealing member (201), the second sealing member (202) and the cylinder body internal sealing member (14) are sealing rings, O-rings, felt, inflatable sealing rings and / or rubber strips.

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