Quick-response high-precision positioning device

Abstract

The utility model discloses a quick-response high-precision positioning device which comprises a cylindrical piezoelectric ceramic tube which is located in a cavity formed by a device base and a device shell. A moving end is arranged at the top of the piezoelectric ceramic tube, a belleville spring is arranged between the moving end and the device shell, and the top of the moving end penetrates through the device shell and extends to the outer side; the piezoelectric ceramic tube is provided with a power wire, the power wire penetrates through the device base and extends to the outside, pre-tightening force is generated through the belleville spring, positioning is carried out through axial strain of the piezoelectric ceramic tube under an external electric field, and the piezoelectric ceramic tube is driven by the pre-tightening force to rotate in the working process. And after the piezoelectric ceramic tube is deformed under the electric field, the displacement output to the moving end of the positioning device quickly tends to be stable, so that the positioning device realizes quick response and stability of positioning, and quick and accurate positioning is completed.

Description

Technical Field

[0001] The utility model relates to the technical field of high-precision positioning, in particular to a fast-response high-precision positioning device. Background Art

[0002] In some positioning applications, such as laser interferometry, the positioning device is required to have a fast response speed, with a response time of microseconds, while the positioning accuracy can be relaxed to 5~20nm. Since the field-induced strain performance of piezoelectric ceramics has characteristics such as hysteresis and creep, it is very difficult to achieve high positioning accuracy through open-loop control. In piezoelectric ceramic positioning technology, piezoelectric ceramics are usually used. 33 * The inverse piezoelectric performance in the direction (parallel to the direction of the external electric field) is achieved, and the open-loop control accuracy is between 15% and 20% of the full stroke. The closed-loop control requires multiple strain detection, calculation and external electric field strength correction, and has a slow response problem, and its response time is usually greater than tens of milliseconds.

[0003] For example, a "three-dimensional micro-positioning platform driven by piezoelectric ceramics" disclosed in Chinese patent documents, with the announcement number: CN115370900A, discloses that the upper platform and the lower platform are provided with support rods at the four corners, the upper platform is provided with a through slot and a mobile platform is provided in the through slot, and the four side walls of the mobile platform are respectively provided with flexible hinges. The advantages of this invention are: the present invention expands the displacement range of the mobile platform by cooperating with the driver and the amplification mechanism; by adopting a multi-link symmetrical guide mechanism, specifically a symmetrical connecting rod, it takes into account the overall structural stiffness while taking into account the displacement stroke, and can eliminate the coupling error and the influence of parasitic displacement on the positioning accuracy to the greatest extent, thereby improving the positioning accuracy; the longitudinal displacement adopts a two-stage amplification structure to achieve two-stage amplification, but this solution does not solve the problem of slow response. Summary of the invention

[0004] In order to solve the problems of slow positioning response and low precision of piezoelectric ceramics in the prior art, the utility model provides a fast-response high-precision positioning device, which utilizes the axial strain of the piezoelectric ceramic tube under an external electric field for positioning, and forms a pre-tightening force on the piezoelectric ceramic tube through a disc spring, so that the positioning device can complete fast and accurate positioning.

[0005] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0006] A fast response high-precision positioning device includes: a cylindrical piezoelectric ceramic tube, the piezoelectric ceramic tube is located in a cavity formed by a device base and a device shell; a moving end is arranged on the top of the piezoelectric ceramic tube, a disc spring is arranged between the moving end and the device shell, and the top of the moving end passes through the device shell and extends to the outside; the piezoelectric ceramic tube is provided with a power supply wire, and the power supply wire passes through the device base and extends to the outside. The disc spring forms a pre-tightening force on the piezoelectric ceramic tube, and the axial strain of the piezoelectric ceramic tube under an external electric field is used for positioning. The pre-tightening force causes the displacement output transmitted to the free end of the piezoelectric ceramic tube after deformation under the electric field to quickly stabilize during the working process, so that the positioning device can achieve rapid response and stability of positioning, thereby completing rapid and accurate positioning.

[0007] Preferably, an upper gasket is provided between the piezoelectric ceramic tube and the bottom surface of the moving end, the bottom surface of the upper gasket is provided with a truncated cone-shaped protrusion that abuts against the piezoelectric ceramic tube, and the upper gasket and the piezoelectric ceramic tube are tightly connected by epoxy resin, so that the piezoelectric ceramic tube can be abutted and fixed from above, which is convenient for assembly.

[0008] Preferably, a lower gasket is provided between the piezoelectric ceramic tube and the device base, the top surface of the lower gasket is provided with a truncated cone-shaped second protrusion that abuts against the piezoelectric ceramic tube, and the lower gasket and the piezoelectric ceramic tube are tightly connected by epoxy resin, so that the piezoelectric ceramic tube can be abutted and fixed from the bottom of the piezoelectric ceramic tube, which is convenient for assembly.

[0009] Preferably, the lower gasket is provided with a wire opening, the wire opening passes through the second truncated cone-shaped protrusion, and the power supply wire passes through the wire opening, so as to realize the connection between the piezoelectric ceramic tube and the external power supply.

[0010] Preferably, the device base and the device housing are connected by threads, and a clamping position is provided on the outer side of the device base, and the clamping position is a flat surface, so as to facilitate mobile use and fix the device to other equipment or structures to achieve positioning application.

[0011] Preferably, the power supply wire is connected to the inner and outer sides of the piezoelectric ceramic tube respectively, the device base is provided with a base opening, and the power supply wire passes through the base opening and extends to the outside to achieve signal transmission.

[0012] Preferably, a screw hole is provided on the top of the device housing, a locking nut is connected to the screw hole, and the bottom end of the locking nut is connected to a disc spring. The locking nut is used to realize the positioning of the moving end, so that the displacement output transmitted to the free end after the piezoelectric ceramic is deformed under the electric field quickly tends to be stable, so as to achieve rapid response and stability of positioning.

[0013] Preferably, electrodes are present on both the inner and outer surfaces of the piezoelectric ceramic tube, and no electrodes are present on the edge areas of the piezoelectric ceramic tube surface near both ends in the tube length direction, and the width of the electrode-free area in the tube length direction is 1 to 5 mm. The electrode arrangement on the inner and outer surfaces of the piezoelectric ceramic tube ensures that the piezoelectric ceramic tube can achieve field-induced strain, and can also alleviate the effect of long-term cyclic strain of the strain zone of the piezoelectric ceramic tube on the fixation of the end face of the piezoelectric ceramic tube through the electrode-free area, such as avoiding the ceramic tube driver in the positioning device from being separated from the upper and lower gaskets during long-term operation, thereby causing abnormal positioning function.

[0014] Preferably, the power supply wire is a coaxial line, the top of the mobile end is a cylindrical protrusion, and the cylindrical protrusion is provided with one of an external thread or an internal thread. The coaxial line avoids the influence of external interference electric field and magnetic field.

[0015] The utility model has the following advantages:

[0016] (1) Using the axial strain of the piezoelectric ceramic tube under an external electric field to output strain / displacement and position, using the piezoelectric ceramic tube in d 31 * (1) The field-induced strain in the direction perpendicular to the external electric field has better linearity and repeatability, ensuring higher positioning accuracy; (2) The disc spring generates a preload force, and this preload force is used to cause the positioning device to deform under the electric field during operation, and the displacement output transmitted to the free end quickly tends to a stable displacement, thereby achieving rapid response and stability of positioning, and the positioning device completes rapid and accurate positioning; (3) The arrangement of internal and external electrodes of the piezoelectric ceramic tube ensures that the piezoelectric ceramic tube in the positioning device can realize the normal operation of the field-induced strain, and can avoid the risk of radial deformation of the piezoelectric ceramic tube covered by the electrode area on the fixed detachment of the ceramic tube abutment position through the electrode-free area, such as avoiding the ceramic tube driver in the positioning device from making sounds and detaching from the upper and lower gaskets during long-term operation, thereby causing abnormal positioning function; (4) The coaxial line is used to avoid the influence of external interference electric and magnetic fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described below are merely exemplary. A person skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0018] Figure 1 It is a schematic diagram of the overall structure in the embodiment.

[0019] Figure 2 It is a schematic diagram of the side cross-sectional structure in the embodiment.

[0020] Figure 3 It is a schematic diagram of the structure without a gasket in the embodiment.

[0021] Figure 4 2 is a schematic diagram of a structure in which the opening is a circular hole in the embodiment.

[0022] In the figure:

[0023] 1-moving end; 2-locking nut; 3-device housing; 4-device base; 5-clamping position; 6-power wire; 7-disc spring; 8-upper gasket; 9-piezoelectric ceramic tube; 10-lower gasket. DETAILED DESCRIPTION

[0024] Based on the embodiments of the present utility model, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present utility model.

[0025] like Figure 1-4 As shown, in a preferred embodiment, the utility model discloses a fast response high-precision positioning device, comprising: a device housing 3 and a device base 4 connected by threads, wherein the device housing 3 is a cylindrical housing opened downward, and the device base 4 is connected to the lower side end surface of the device housing 3. The cross-sectional shape of the device base 4 is the same as the cross-sectional shape and size of the device housing 3.

[0026] The lower side end surface of the device base 4 is a flat plane. When the lower side end surface of the device base 4 is a flat plane, the device is connected to other equipment or mechanisms through the device shell 3, and two parallel planes can be made on the side of the shell 3 cylinder wall to facilitate the clamping and positioning of the device through the shell. And the two parallel planes are arranged in the same way as the clamping position 5.

[0027] In other embodiments, the device base 4 is a threaded base. In this case, the device is connected to other equipment or mechanisms through the threads of the threaded base.

[0028] The side of the device base 4 is provided with a clamping position 5, and the clamping position 5 is symmetrically arranged on the two sides of the device base 4. The clamping position 5 is provided with a clamping plane, and the clamping plane is perpendicular to the upper and lower end surfaces of the device base 4. The device is clamped and fixed from both sides of the device base 4 through the clamping position 5, which is convenient for clamping the device in other equipment or mechanisms, thereby realizing positioning applications.

[0029] The device base 4 is also provided with a base opening, and the base opening is arranged on the side of the device base 4. The opening direction of the base opening is radially outward along the device base 4, and the base opening is also connected to the upper end surface of the device base 4. That is, the two ends of the base opening are respectively connected to the side surface and the upper end surface of the device base 4. Thus, the internal cavity surrounded by the device base 4 and the device housing 3 is connected to the outside.

[0030] In other embodiments, a lower gasket 10 is disposed on the upper end surface of the device base 4, and the lower gasket 10 and the device base 4 can be tightly connected by epoxy resin, screws, etc. The cross-sectional shape of the lower gasket 10 is circular, and the diameter of the lower gasket 10 is smaller than the diameter of the device base 4. The lower gasket 10 includes one of non-conductive rigid materials such as plastic and ceramic.

[0031] The upper end surface of the lower gasket 10 is provided with a truncated cone-shaped second protrusion, the cross-sectional shape of the truncated cone-shaped second protrusion is circular, the diameter of the truncated cone-shaped second protrusion is smaller than the diameter of the lower gasket 10, and the height of the truncated cone-shaped second protrusion is not higher than the height of the electrode-free area of ​​the piezoelectric ceramic tube 9. The material of the truncated cone-shaped second protrusion is the same as that of the lower gasket 10.

[0032] In other embodiments, the lower gasket 10 and the truncated cone-shaped second protrusion are integrally injection molded.

[0033] The lower gasket 10 is provided with a wire opening, and the opening direction of the wire opening is from the center to the edge of the lower gasket 10 along the radial direction of the lower gasket 10, and the wire opening passes through the upper and lower end surfaces of the lower gasket 10. The wire opening extends upward to the upper end surface of the truncated cone-shaped second protrusion, that is, the wire opening is connected to the upper end surface of the truncated cone-shaped second protrusion, the lower end surface of the lower gasket 10, the side surface of the lower gasket 10 and the side surface of the truncated cone-shaped second protrusion. The opening direction of the wire opening in the part of the truncated cone-shaped second protrusion is the same as that in the lower gasket 10.

[0034] The sum of the height of the lower gasket 10 and the height of the second truncated cone-shaped protrusion is in the range of 1 to 5 mm.

[0035] The upper end surface of the lower gasket 10 is fixedly connected with a piezoelectric ceramic tube 9, which is cylindrical, has a wall thickness of 0.3-3 mm, and has a tube length of 5-40 mm. Electrodes are present on the inner and outer surfaces of the piezoelectric ceramic tube 9. The piezoelectric ceramic tube 9 is also provided with an electrode-free area, the starting ends of which are the upper and lower edges of the piezoelectric ceramic tube, respectively, and the width of the electrode-free area in the tube length direction is 1-5 mm. The electrodes on the piezoelectric ceramic tube 9 can ensure that the piezoelectric ceramic tube 9 generates sound field-induced strain, thereby generating deformation in the tube length direction; and the electrode-free area can reduce the relative position change of the piezoelectric ceramic tube 9 with the base in the tube diameter direction during operation, thereby preventing the piezoelectric ceramic tube 9 from being separated from the device base 4. The piezoelectric ceramic tube 9 is composed of zirconate-titanate-based piezoelectric ceramic material, and a lead zirconate-titanate-based piezoelectric ceramic material with good linearity and repeatability is selected.

[0036] The positive linearity of the piezoelectric ceramic tube 9 in the tube length direction during operation is less than 5% at full stroke, and the positive repeatability is less than 2% at full stroke. When the stroke of the piezoelectric ceramic tube 9 is 0.5 microns, the positioning accuracy of the piezoelectric ceramic tube 9 in the device ranges from plus or minus 5 nanometers to plus or minus 8 nanometers.

[0037] The piezoelectric ceramic tube 9 is tightly connected to the lower gasket 10 through epoxy resin, and the lower end of the piezoelectric ceramic tube 9 is fixedly connected to the upper end surface of the lower gasket 10. The inner diameter of the piezoelectric ceramic tube 9 is larger than the diameter of the cylindrical second protrusion, and the diameter difference is between 0.05 and 1 mm.

[0038] In other embodiments, the lower end of the piezoelectric ceramic tube 9 is fixedly connected to the upper end face of the lower gasket 10 and the cylindrical second protrusion at the same time, that is, the lower end face of the piezoelectric ceramic tube 9 is fixedly connected to the upper end face of the lower gasket 10, and the side of the lower end of the piezoelectric ceramic tube 9 is fixedly connected to the side of the cylindrical second protrusion. The cylindrical second protrusion and the lower gasket 10 are connected to the electrode-free area at the bottom of the piezoelectric ceramic tube 9. In the working process, the internal stress at the connection between the piezoelectric ceramic tube 9 and the lower gasket 10 is reduced, thereby avoiding the lower gasket 10 from being separated from the piezoelectric ceramic tube 9 due to internal stress under long-term working conditions, thereby ensuring the reliability of the positioning process.

[0039] In other embodiments, the piezoelectric ceramic tube 9 is connected to a power supply wire 6, and the power supply wire 6 is arranged on both sides of the inside and outside of the piezoelectric ceramic tube 9. The base opening is arranged corresponding to the wire opening and is located in the same direction of the same radial line. The power supply wire 6 passes through the lower gasket 10 and the wire opening in the cylindrical second protrusion to the base opening, and extends through the base opening to the outside. The power supply wire 6 is a coaxial line to avoid the influence of external interference electric field and magnetic field.

[0040] In other embodiments, the top of the piezoelectric ceramic tube 9 is fixedly connected with an upper gasket 8, and the lower end face of the upper gasket 8 is provided with a truncated cone-shaped protrusion, and the diameter of the truncated cone-shaped protrusion is the same as the inner diameter of the piezoelectric ceramic tube 9. The inner diameter of the piezoelectric ceramic tube 9 is larger than the diameter of the cylindrical second protrusion, and the diameter difference is between 0.05 and 1 mm. The side of the truncated cone-shaped protrusion is fixedly connected to the inner wall of the piezoelectric ceramic tube 9, and the lower end face of the upper gasket 8 is connected to the upper end face of the piezoelectric ceramic tube 9. The piezoelectric ceramic tube 9, the upper gasket 8 and the truncated cone-shaped protrusion are tightly connected by epoxy resin.

[0041] In other embodiments, the lower end of the piezoelectric ceramic tube 9 is fixedly connected to the upper end surface of the lower gasket 10 and the cylindrical second protrusion at the same time, that is, the lower end surface of the piezoelectric ceramic tube 9 is fixedly connected to the upper end surface of the lower gasket 10, and the side surface of the lower end of the piezoelectric ceramic tube 9 is fixedly connected to the side surface of the cylindrical second protrusion. The cylindrical second protrusion and the lower gasket 10 are connected in the electrode-free area at the bottom of the piezoelectric ceramic tube 9.

[0042] The diameter of the upper gasket 8 is the same as that of the lower gasket 10, and the material of the upper gasket 8 includes non-conductive rigid materials such as plastic or ceramic. The sum of the heights of the upper gasket 8 and the truncated cone-shaped protrusion is in the range of 1 to 5 mm. The upper gasket 8 and the truncated cone-shaped protrusion are both connected to the electrode-free area at the top of the piezoelectric ceramic tube 9, so that during the working process, the internal stress at the connection between the piezoelectric ceramic tube 9 and the upper gasket 8 is reduced, thereby avoiding the upper gasket 8 and the piezoelectric ceramic tube 9 from being separated due to internal stress under long-term working conditions, thereby ensuring the reliability of the positioning process.

[0043] In other embodiments, the upper end face of the upper gasket 8 is fixedly connected with the mobile end 1, and the mobile end 1 moves up and down following the expansion and contraction of the piezoelectric ceramic tube 9 in the direction of the tube length. The lower end face of the mobile end 1 is a flat surface, and the lower end face of the mobile end 1 is fixedly connected to the upper end face of the upper gasket 8. The upper gasket 8 is fixedly connected to the mobile end 1 by means of epoxy resin tight connection, screws, etc. The top of the mobile end 1 extends to the outside through the device housing 3, the cross-section of the top of the mobile end 1 is circular, and the top of the mobile end 1 is a cylindrical protrusion. At this time, the mobile end 1 is divided into two parts by the device housing 3, one part of which is located in the device housing 3 and connected to the upper gasket 8 or the piezoelectric ceramic tube 9, and the other part is located outside the device housing 3 and connected to other devices or mechanisms.

[0044] The diameter of the moving end 1 is slightly larger than the diameter of the upper gasket 8 , the diameter of the moving end 1 is larger than the diameter of the piezoelectric ceramic tube 9 , and the diameter of the cylindrical protrusion is smaller than the diameter of the moving end 1 .

[0045] In other embodiments, a disc spring 7 is provided between the mobile end 1 and the inner wall of the device housing 3, and the disc spring 7 is located outside the cylindrical top of the mobile end 1, and the disc spring 7 presses downward the upper end surface of the mobile end 1. The disc spring 7 provides a downward preload force, and then the mobile end 1 generates a preload force on the piezoelectric ceramic tube 9. The preload force causes the piezoelectric ceramic tube 9 to quickly tend to a stable displacement after being deformed under the electric field during the working process, thereby achieving a rapid response and stability of the positioning.

[0046] In other embodiments, the upper end surface of the device housing 3 is provided with a screw hole, and the screw holes include a plurality of symmetrically arranged screw holes, and the symmetry center is located at the intersection of the center line of the device housing 3 and the upper end surface. The diameter of the screw hole is smaller than the diameter of the cylindrical protrusion. The cylindrical protrusion is located at the center of the upper end surface of the mobile terminal 1, and the cylindrical protrusion extends outward from the center of the upper end surface of the device housing 3. The screw holes are arranged on both sides of the cylindrical protrusion.

[0047] The screw hole passes through the device housing 3 downward and is connected to the inside of the device housing 3. A locking nut 2 is threadedly connected in the screw hole, and the locking nut 2 extends downward through the screw hole to the inside of the device housing 3. The locking nut 2 abuts against the upper side of the disc spring 7. The pressure of the locking nut 2 on the disc spring 7 is adjusted by the position of the locking nut 2 in the screw hole, thereby changing the preload force of the disc spring 7. By adjusting the preload force on the piezoelectric ceramic tube 9 through the locking nut 2, the maximum displacement, response time, etc. of the piezoelectric ceramic tube 9 and the positioning device can be adjusted.

[0048] In addition, the preload force on the piezoelectric ceramic tube 9 can be changed by changing the size of the disc spring 7 or using disc springs 7 with different damping, thereby adjusting the stroke (maximum displacement) and response time of the piezoelectric ceramic tube 9 and the positioning device.

[0049] In other embodiments, the piezoelectric ceramic tube 9 is directly placed in the cavity formed by the device housing 3 and the device base 4, and the piezoelectric ceramic tube 9 is directly fixed to the mobile end 1. The upper gasket 8 and the lower gasket 10 are not required, and a simpler structure is used. However, the structural size design and assembly requirements of the piezoelectric ceramic tube 9 are more stringent in this solution.

[0050] In other embodiments, the cylindrical protrusion includes one of an external thread, an internal thread, a flat head and a ball head, and the cylindrical protrusion is fixedly connected to the mirror frame and the reflection frame to achieve the function of rapid phase shift of the laser.

[0051] In another specific embodiment, the sum of the height of the device housing 3 and the height of the device base 4 is in the range of 10-60 mm, and the outer diameter of the device housing 3 and the outer diameter of the device base 4 are both in the range of 10-35 mm. The number of the screw holes is two.

[0052] In other embodiments, the disc spring is replaced by a helical spring. The positioning stroke is 0.2-4 microns, and preferably 0.2-0.7 microns.

[0053] In other embodiments, the wire opening is a round hole structure, and the base opening is also a round hole structure, so that the wire passes through the round hole and extends outward.

[0054] In other embodiments, when there is no gasket, the lower end surface of the moving end and the upper end surface of the device base are also provided with a circular protrusion that abuts against the piezoelectric ceramic tube. And the base opening extends from the upper end surface of the base and penetrates to the bottom surface or side surface of the device base.

[0055] In other embodiments, the device housing 3 can be split into two parts, one part is a cylindrical housing wall, and the other part is a device cover. The device cover and the cylindrical housing wall can be fixed by their side threads. The device cover and the disc spring together apply a preload to the upper end surface of the mobile end 1.

[0056] These modifications or improvements made on the basis of the present utility model without departing from the spirit of the present utility model shall all fall within the scope of protection required by the present utility model.

Claims

1. A fast response high precision positioning device, characterized in that: include: A cylindrical piezoelectric ceramic tube is located in a cavity formed by a device base and a device shell; a moving end is arranged on the top of the piezoelectric ceramic tube, a disc spring is arranged between the moving end and the device shell, and the top of the moving end passes through the device shell and extends to the outside; the piezoelectric ceramic tube is provided with a power lead, and the power lead passes through the device base and extends to the outside.

2. A fast response high precision positioning device according to claim 1, characterized in that: An upper gasket is provided between the piezoelectric ceramic tube and the bottom surface of the moving end, a truncated cone-shaped protrusion abutting against the piezoelectric ceramic tube is provided on the bottom surface of the upper gasket, and the upper gasket and the piezoelectric ceramic tube are tightly connected by epoxy resin.

3. A fast response high precision positioning device according to claim 1 or 2, characterized in that: A lower gasket is arranged between the piezoelectric ceramic tube and the device base, a truncated cone-shaped second protrusion abutting against the piezoelectric ceramic tube is arranged on the top surface of the lower gasket, and the lower gasket is tightly connected to the piezoelectric ceramic tube through epoxy resin.

4. A fast response high precision positioning device according to claim 3, characterized in that: The lower gasket is provided with a wire opening, the wire opening penetrates the frustum-shaped second protrusion, and the power supply wire passes through the wire opening.

5. A fast response high precision positioning device according to claim 1 or 2, characterized in that: The device base and the device shell are connected by threads, and a clamping position is arranged on the outer side of the device base, and the clamping position is a flat surface.

6. A fast response high precision positioning device according to claim 4, characterized in that: The power supply wire is connected to the inner and outer sides of the piezoelectric ceramic tube respectively, the device base is provided with a base opening, and the power supply wire passes through the base opening and extends to the outside.

7. A fast response high precision positioning device according to claim 1 or 2, characterized in that: A screw hole is arranged on the top of the device shell, a locking nut is connected in the screw hole, and the bottom end of the locking nut is connected to a disc spring.

8. The fast response high precision positioning device according to claim 1, characterized in that: Electrodes are present on both the inner and outer surfaces of the piezoelectric ceramic tube, but no electrodes are present in the edge regions near both ends of the piezoelectric ceramic tube surface in the tube length direction, and the width of the electrode-free region in the tube length direction is 1-5 mm.

9. A fast response high precision positioning device according to claim 7, characterized in that: The power supply wire is a coaxial line, the top of the moving end is a cylindrical protrusion, and the cylindrical protrusion is provided with one of an external thread or an internal thread.

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