A six-degree-of-freedom quasi-zero-stiffness vibration isolation platform

Abstract

The present invention provides a six-degree-of-freedom quasi-zero stiffness vibration isolation platform, which includes a tabletop, vibration isolators and a bottom plate. The vibration isolators include a top plate, a base, vertical plates and air springs. The vertical plates are vertically installed around the top of the base. An air spring is installed in the middle of the bottom of the top plate. Four support rods are arranged in a rectangle around the air spring at the bottom of the top plate. A support plate is installed at the bottom of the air spring. A ball screw is installed at the bottom of the support plate. A ball nut plate is sleeved on the ball screw. The top of the ball nut plate is connected to the support rods. Negative stiffness devices are respectively installed between the middle of the periphery of the ball nut plate and the vertical plates. A turntable is vertically connected to the bottom of the ball screw. Metal springs A are respectively installed between the middle of the periphery of the turntable and the vertical plates. A disc spring is connected between the support plate and the support rods. The present invention can achieve quasi-zero stiffness both vertically and horizontally and has the ability to adjust the bearing capacity and stiffness.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration isolation devices, and specifically to a six-degree-of-freedom quasi-zero stiffness vibration isolation platform. Background Technique

[0002] At present, the semiconductor industry is developing rapidly, and the accuracy requirements of semiconductor production equipment are getting higher and higher. The equipment is also more and more sensitive to the requirements of environments such as micro-vibrations. A little micro-vibration will reduce the yield rate of the equipment, and even make the equipment unable to work properly. Therefore, the isolation of micro-vibrations becomes more and more important.

[0003] A quasi-zero stiffness isolator is a combined isolator that parallelly connects positive and negative stiffness elastic components to obtain zero stiffness at the static equilibrium position. This type of isolator has a relatively large static stiffness and can bear the weight of the equipment to be isolated. When the equipment vibrates at the static equilibrium position, the stiffness is very low, even tending to zero, which is beneficial to low-frequency vibration isolation. Most quasi-zero stiffness isolators are designed for a single vibration isolation object. Once the isolator is manufactured, the structural parameters cannot be changed. Therefore, when the vibration isolation mass changes, such as overloading or underloading, the isolator no longer has the quasi-zero stiffness characteristic, and the vibration isolation performance deteriorates or even the effect is worse than that of a linear vibration isolation system, which greatly limits its application range. A small number of isolators can still have the quasi-zero stiffness characteristic under variable loads, but there is a problem that the vibration isolation mass cannot change continuously. The isolator can only maintain quasi-zero stiffness at several specific masses, with a small application range and generally unable to meet the vibration isolation requirements for large loads. In addition, currently, most quasi-zero stiffness isolators can only achieve quasi-zero stiffness for a single vertical degree of freedom and cannot achieve multi-degree-of-freedom quasi-zero stiffness. Summary of the Invention

[0004] The purpose of the present invention is to provide a six-degree-of-freedom quasi-zero stiffness vibration isolation platform to solve the problems existing in the above background technique.

[0005] The technical solution of the present invention is realized as follows: A six-degree-of-freedom quasi-zero stiffness vibration isolation platform, including a tabletop, vibration isolators, and a bottom plate. Vibration isolators are installed between the four corners of the top of the bottom plate and the tabletop. The vibration isolator includes a top plate, a base, a vertical plate, and an air spring. The vertical plate is vertically installed around the top of the base. An air spring is installed in the middle of the bottom of the top plate. Four support rods are installed around the air spring at the bottom of the top plate in a rectangular arrangement. A support plate is installed at the bottom of the air spring. A ball screw is installed at the bottom of the support plate. A ball nut plate is sleeved on the ball screw. The top of the ball nut plate is connected to the support rod. Negative stiffness devices are respectively installed between the middle of the periphery of the ball nut plate and the vertical plate. The bottom of the ball screw is vertically connected to a turntable. The bottom of the turntable is connected to the base through a spherical hinge A. Metal springs A are respectively installed between the middle of the periphery of the turntable and the vertical plate. A disc spring is connected between the support plate and the support rod. Metal springs B are installed between the vertical plate and the support rods on the left and rear sides. Horizontal voice coil motors are installed between the vertical plate and the support rods on the right and front sides. A vertical voice coil motor is installed between the middle of the top of the vertical plate and the top plate. The negative stiffness device includes a rhombic link. Vertical rods are respectively and vertically installed at the upper and lower connection points of the rhombic link. A permanent magnet is installed at the bottom of the upper vertical rod, and an electromagnet is installed at the top of the lower vertical rod. The negative stiffness device is connected to the ball nut plate through a spherical hinge B. The negative stiffness device is connected to the vertical plate through a spherical hinge C. The metal spring A is connected to the turntable through a spherical hinge D. The metal spring A is connected to the vertical plate through a spherical hinge E. The metal spring B is connected to the support rod through a spherical hinge F. An acceleration sensor and a position sensor are also installed at the bottom of the top plate. A controller is also installed at the top of the base. An air inlet pipe is installed on one side of the bottom of the air spring. A servo valve is installed on the air inlet pipe. A linear bearing is also installed between the ball screw and the support plate.

[0006] Further, the magnetic force between the electromagnet and the permanent magnet shows an attractive force.

[0007] Further, the tabletop, bottom plate, top plate, and base are all made of stainless steel plates into rectangular structures.

[0008] Further, the spherical hinge A, spherical hinge B, spherical hinge C, spherical hinge D, spherical hinge E, and spherical hinge F are all flexible spherical hinges.

[0009] Further, a support block A is also installed between the metal spring B and the vertical plate.

[0010] Further, a support block B is also installed between the horizontal voice coil motor and the vertical plate.

[0011] Further, the controller is connected to the electromagnet, vertical voice coil motor, horizontal voice coil motor, acceleration sensor, and position sensor through cables.

[0012] The beneficial effects of the present invention are as follows:

[0013] In the present invention, the vertical and horizontal negative stiffness of the system is adjusted by combining the diamond-shaped rod with the magnetic structure. The air spring provides vertical positive stiffness, and the metal spring A provides horizontal positive stiffness. The vertical positive stiffness of the system can be adjusted by controlling the air pressure of the cylinder, and the negative stiffness of the system can be adjusted by adjusting the magnitude of the current of the electromagnet, so as to adjust the vertical positive and negative stiffness of the system, making the system reach static quasi-zero stiffness at the initial equilibrium position, which can meet different models of precision instruments.

[0014] When vertical vibration occurs in the present invention, the diamond-shaped connecting rod of the negative stiffness device is stretched, the distance between the permanent magnet and the electromagnet becomes smaller, and the gravitational force between the two becomes larger, intensifying the trend of the vertical movement of the system. At this time, vertical negative stiffness is provided for the system, while the air spring provides vertical positive stiffness at this time. The negative stiffness device and the air spring form a vertical positive and negative stiffness system to achieve vertical quasi-zero stiffness.

[0015] When horizontal vibration occurs in the present invention, the diamond-shaped connecting rod of the negative stiffness device on one side in the moving direction is compressed, the distance between the permanent magnet and the electromagnet becomes larger, and the gravitational force between the two becomes smaller. The diamond-shaped connecting rods of the negative stiffness devices in the other three directions are stretched, the distance between the permanent magnet and the electromagnet becomes smaller, and the gravitational force between the two becomes larger, intensifying the trend of the horizontal movement of the system. At this time, horizontal negative stiffness is provided for the system, while the metal spring A provides horizontal positive stiffness at this time. The negative stiffness device and the metal spring A form a horizontal positive and negative stiffness system to achieve horizontal quasi-zero stiffness.

[0016] For vertical high-frequency vibration sources in the present invention, secondary vibration reduction is achieved through the disc spring and the metal spring A. For horizontal high-frequency vibration sources, vibration reduction is achieved through the metal spring B, so that the system can achieve vibration reduction for relatively high vibration frequencies; for vertical low-frequency and horizontal low-frequency vibration sources, vibration reduction is achieved through the voice coil motor, so that the system can achieve vibration reduction for relatively low vibration frequencies. The vibration isolation band of the system is relatively wide, and vibration control in the range of 0.1 Hz to 250 Hz can be achieved.

[0017] The present invention can achieve quasi-zero stiffness both vertically and horizontally, and the system has a large static stiffness and a large bearing capacity, which can meet the bearing requirements of precision instruments of 5000 kg. Moreover, it has a high positioning accuracy, has the ability to adjust the bearing capacity and stiffness, can adapt to different models of precision instruments, has a wide application range and strong versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of the present invention.

[0019] Figure 2 It is a schematic structural diagram of the vibration isolator of the present invention.

[0020] In the figure, 1 - tabletop, 2 - vibration isolator, 3 - bottom plate, 201 - top plate, 202 - base, 203 - vertical plate, 204 - air spring, 205 - support rod, 206 - support plate, 207 - ball screw, 208 - ball nut plate, 209 - negative stiffness device, 2091 - diamond link, 2092 - vertical rod, 2093 - permanent magnet, 2094 - electromagnet, 210 - turntable, 211 - metal spring A, 212 - disc spring, 213 - metal spring B, 214 - vertical voice coil motor, 215 - horizontal voice coil motor, 216 - ball joint A, 217 ball joint B, 218 - ball joint C, 219 - ball joint D, 220 - ball joint E, 221 - ball joint F, 222 - acceleration sensor, 223 - position sensor, 224 - controller, 225 - intake pipe, 226 - servo valve, 227 - linear bearing, 228 - support block A, 229 - support block B. Detailed implementation manners

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] As Figure 1-2As shown in the figure, a six-degree-of-freedom quasi-zero stiffness vibration isolation platform includes a tabletop 1, vibration isolators 2 and a bottom plate 3. Vibration isolators 2 are installed between the four corners at the top of the bottom plate 3 and the tabletop 1. The vibration isolator 2 includes a top plate 201, a base 202, a vertical plate 203 and an air spring 204. The vertical plate 203 is vertically installed around the top of the base 202. An air spring 204 is installed in the middle of the bottom of the top plate 201. Four support rods 205 are installed around the air spring 204 at the bottom of the top plate 201 in a rectangular arrangement. A support plate 206 is installed at the bottom of the air spring 204. A ball screw 207 is installed at the bottom of the support plate 206. A ball nut plate 208 is sleeved on the ball screw 207. The top of the ball nut plate 208 is connected to the support rod 205. Negative stiffness devices 209 are respectively installed between the middle of the four sides of the ball nut plate 208 and the vertical plate 203. The bottom of the ball screw 207 is vertically connected to a turntable 210. The bottom of the turntable 210 is connected to the base 202 through a spherical hinge A216. Metal springs A211 are respectively installed between the middle of the four sides of the turntable 210 and the vertical plate 203. A disc spring 212 is connected between the support plate 206 and the support rod 205. Metal springs B213 are installed between the vertical plate 203 and the support rods 205 on the left and rear sides. Horizontal voice coil motors 215 are installed between the vertical plate 203 and the support rods 205 on the right and front sides. A vertical voice coil motor 214 is installed between the middle of the top of the vertical plate 203 and the top plate 201. The negative stiffness device 209 includes a rhombic link 2091. Vertical rods 2092 are respectively and vertically installed at the upper and lower joints of the rhombic link 2091. A permanent magnet 2093 is installed at the bottom of the upper vertical rod 2092. An electromagnet 2094 is installed at the top of the lower vertical rod 2092. The negative stiffness device 209 is connected to the ball nut plate 208 through a spherical hinge B217. The negative stiffness device 209 is connected to the vertical plate 203 through a spherical hinge C218. The metal spring A211 is connected to the turntable 210 through a spherical hinge D219. The metal spring A211 is connected to the vertical plate 203 through a spherical hinge E220. The metal spring B213 is connected to the support rod 205 through a spherical hinge F221. An acceleration sensor 222 and a position sensor 223 are also installed at the bottom of the top plate 201. A controller 224 is also installed at the top of the base 202. An air inlet pipe 225 is installed on one side of the bottom of the air spring 204. A servo valve 226 is installed on the air inlet pipe 225. A linear bearing 227 is also installed between the ball screw 207 and the support plate 205.

[0023] The magnetic force between the electromagnet 2093 and the permanent magnet 2092 shows an attractive force.

[0024] The tabletop 1, the bottom plate 2, the top plate 201 and the base 202 are all made of stainless steel plates into rectangular structures.

[0025] The ball joints A216, B217, C218, D219, E220, and F221 are all flexible ball joints.

[0026] A support block A228 is also installed between the metal spring B213 and the vertical plate 203.

[0027] A support block B229 is also installed between the horizontal voice coil motor 215 and the vertical plate 203.

[0028] The controller 224 is connected to the electromagnet 2093, the vertical voice coil motor 214, the horizontal voice coil motor 215, the acceleration sensor 222, and the position sensor 223 through cables.

[0029] During installation, first determine the weight of the load precision instrument, and then adjust the air pressure of the air spring 204 by controlling the servo valve 226 according to the weight of the precision instrument to ensure that the load-bearing requirement can be met. Then place the precision instrument on the table 1. Control the current magnitude of the electromagnet 2094 of the four negative stiffness devices 209 through the controller 224, so as to control the strength of the electromagnetic field generated by it, and further control the negative stiffness magnitude of the negative stiffness device 209, forming a positive and negative stiffness parallel system with the air spring 204. And the positive stiffness magnitude of the system can be adjusted by controlling the air pressure of the air spring 204, so as to adjust the positive and negative stiffness in the vertical direction of the system. Through the adjustment of the positive and negative stiffness, the system reaches static quasi-zero stiffness at the initial equilibrium position. At this time, the diamond link 2091 of the negative stiffness device 209 is in the horizontal plane, and the metal spring 211 is in the natural telescopic state.

[0030] During operation, vibration signals are collected by the acceleration sensor 222 and the position sensor 223, and then the signals are transmitted to the controller 224. When there is a vertical high-frequency vibration source, first, the first high-frequency vibration reduction is achieved through the disc spring 212. Secondly, the vertical rod 205 drives the ball nut disc 208 to move up and down, thereby driving the ball screw 207 to rotate, and further driving the turntable 210 to rotate. At this time, the metal spring A211 is stretched to achieve the second high-frequency vibration reduction in the vertical direction. When there is a vertical low-frequency vibration source, vibration reduction is achieved by controlling the vertical voice coil motor 214 through the controller 224. When there is a horizontal high-frequency vibration source, high-frequency vibration reduction is achieved through the metal spring B213. When there is a horizontal low-frequency vibration source, vibration reduction is achieved by controlling the horizontal voice coil motor 215 through the controller 224.

[0031] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A six-degree-of-freedom quasi-zero-stiffness vibration isolation platform, comprising a table, a vibration isolator and a bottom plate, characterized in that: Vibration isolators are installed between the four corners of the top of the bottom plate and the table top, and the vibration isolator includes a top plate, a base, a vertical plate and an air spring. The vertical plate is vertically installed around the top of the base, and an air spring is installed in the middle of the bottom of the top plate. Four support rods are installed in a rectangular arrangement at the bottom of the top plate and around the air spring. A support plate is installed at the bottom of the air spring, and a ball screw is installed at the bottom of the support plate. A ball nut disk is mounted on the ball screw, and the top of the ball nut disk is connected to the support rod. Negative stiffness devices are respectively installed between the middle of the four sides of the ball nut disk and the vertical plate. A turntable is vertically connected to the bottom of the ball screw, and the bottom of the turntable is connected to the base through a ball joint A. Metal springs A are respectively installed between the middle of the four sides of the turntable and the vertical plate. A disc spring is connected between the support plate and the support rod, and a metal spring B is installed between the vertical plate and the left and rear support rods. A horizontal voice coil motor is installed between the support rod on the front side, a vertical voice coil motor is installed between the middle of the top of the vertical plate and the top plate, the negative stiffness device includes a diamond connecting rod, and vertical rods are vertically installed at the upper and lower connections of the diamond connecting rod, wherein a permanent magnet is installed at the bottom of the upper vertical rod, and an electromagnet is installed at the top of the lower vertical rod, the negative stiffness device is connected to the ball nut plate through a ball joint B, the negative stiffness device is connected to the vertical plate through a ball joint C, the metal spring A is connected to the turntable through a ball joint D, the metal spring A is connected to the vertical plate through a ball joint E, the metal spring B is connected to the support rod through a ball joint F, an acceleration sensor and a position sensor are also installed at the bottom of the top plate, a controller is also installed on the top of the base, an air intake pipe is installed on one side of the bottom of the air spring, a servo valve is installed on the air intake pipe, and a linear bearing is also installed between the ball screw and the support plate.

2. A six-degree-of-freedom quasi-zero stiffness vibration isolation platform according to claim 1, characterized in that: The magnetic force between the electromagnet and the permanent magnet manifests as an attractive force.

3. The six-degree-of-freedom quasi-zero stiffness vibration isolation platform according to claim 1, characterized in that: The table top, bottom plate, top plate and base are all made of stainless steel plates into a rectangular structure.

4. The six-degree-of-freedom quasi-zero stiffness vibration isolation platform according to claim 1, characterized in that: The ball joint A, ball joint B, ball joint C, ball joint D, ball joint E and ball joint F are all flexible ball joints.

5. The six-degree-of-freedom quasi-zero stiffness vibration isolation platform according to claim 1, characterized in that: A support block A is also installed between the metal spring B and the vertical plate.

6. The six-degree-of-freedom quasi-zero-stiffness vibration isolation platform according to claim 1, characterized in that: A support block B is also installed between the horizontal voice coil motor and the vertical plate.

7. The six-degree-of-freedom quasi-zero-stiffness vibration isolation platform according to claim 1, characterized in that: The controller is connected with the electromagnet, the vertical voice coil motor, the horizontal voice coil motor, the acceleration sensor and the position sensor through cables.

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