CN103062284B - Zero-rigidity vibration isolator of double-layer air-flotation orthogonal decoupling and flexible film angle decoupling - Google Patents

Abstract

The zero-stiffness vibration isolator with double-layer air bearing orthogonal decoupling and flexible membrane angle decoupling belongs to the field of precision vibration isolation technology. The floating surface is lubricated and supported, the degree of freedom of horizontal linear motion between the upper and lower mounting plates is decoupled by double-layer orthogonal air bearing guide rails, the degree of freedom of angular motion between the two is decoupled by a flexible membrane, and the voice coil motor , Displacement sensors, limit switches, controllers, and drivers constitute a position closed-loop feedback control system to precisely control the relative positions of the upper and lower mounting plates; the invention has three-dimensional zero stiffness, high positioning accuracy, linear motion and angular motion degrees of freedom The fully decoupling feature can effectively solve the problem of high-performance vibration isolation in ultra-precision measuring instruments and processing equipment, especially in step-and-scan lithography machines.

Description

Zero-stiffness vibration isolator with double-layer air bearing orthogonal decoupling and flexible membrane angle decoupling

technical field

The invention belongs to the technical field of precision vibration isolation, and mainly relates to a zero-stiffness vibration isolator with double-layer air flotation orthogonal decoupling and flexible membrane angle decoupling.

Background technique

With the continuous improvement of ultra-precision machining and measurement accuracy, environmental vibration has become an important factor restricting the improvement of the accuracy and performance of ultra-precision machining equipment and measuring instruments. In particular, the ultra-large-scale integrated circuit processing equipment represented by the step-scan lithography machine is extremely technically intensive and complex, and the key technical indicators have reached the limit of the existing technology, representing the highest level of ultra-precision processing equipment. Precision vibration isolation has become the core key technology in this type of equipment; the line width of the step-and-scan lithography machine has reached 22nm and below, the positioning accuracy and overlay accuracy of silicon wafers have reached several nanometers, and the movement speed of the workpiece table has reached 1m/s Above, the acceleration of the workpiece table reaches dozens of times of the acceleration of gravity, which poses a new challenge to the existing vibration isolation technology. First of all, the lithography machine needs to provide an "ultra-quiet" working environment for the metrology system and the lithography objective lens, and at the same time needs to drive the workpiece table to move at high speed and high acceleration, which poses extremely strict requirements on the vibration isolation performance of the vibration isolation system. It is required that the natural frequencies in the three directions must be below 1Hz; secondly, the relative position between the various components of the lithography machine, such as the distance between the lithography objective lens and the surface of the silicon wafer, has very strict requirements and is in a position closed loop Under the control of the feedback control system, the relative position accuracy between the upper and lower mounting plates of the vibration isolator is required to reach the order of 10 μm, and the positioning accuracy of the traditional vibration isolator is far from meeting the requirements.

According to the vibration isolation theory, the natural frequency of a passive vibration isolator is proportional to the stiffness and inversely proportional to the load mass. Therefore, under the premise of a certain load mass, reducing the stiffness of the vibration isolator is to reduce the natural frequency and improve low frequency and ultra-low frequency vibration isolation. efficient way to perform. Vibration isolators in the form of traditional air springs have an inherent contradiction between static load capacity and stiffness. At the same time, they are constrained by factors such as material properties and structural stiffness. It is very difficult to further reduce their stiffness, especially the horizontal stiffness. In response to this problem, the researchers introduced the "pendulum" structure into the air spring vibration isolator to achieve the purpose of reducing the horizontal stiffness of the vibration isolator (1. Nikon Corporation. Vibration Isolator With Low Lateral Stiffness. US Patent Publication No.: US20040065517A1 ; 2. U.S.Philips Corporation. Positioning Device with a Force Actuator System for Compensating Center-of-gravity Displacements, and Lithographic Device Provided with Such APositioning Device. U.S. Patent No.: US005844664A). This method can reduce the horizontal stiffness of the air spring isolator to a certain extent and improve its low-frequency vibration isolation performance. The problems of this method are as follows: 1) Due to the constraints of material properties and structural stiffness, the amplitude of vertical and horizontal stiffness reduction of the vibration isolator is limited; 2) The vertical and horizontal positioning accuracy of the air spring vibration isolator is very poor, It cannot meet the requirements of the photolithography process; 3) To achieve a lower horizontal stiffness requires a larger pendulum length, resulting in excessive height of the vibration isolator, prone to string-membrane resonance, and poor stability.

Through the analysis of the technical scheme of the existing air spring isolator, it can be seen that the existing air spring isolator is difficult to meet the requirements of ultra-low stiffness and high positioning accuracy of the lithography machine. The German IDE company proposed a vibration isolator technology solution that abandons the traditional rubber air spring (1. Integrated Dynamics Engineering GmbH. Isolatorgeometrie Eines Schwingungsisolationssystem. European Patent No.: EP1803965A2; 2. Integrated Dynamics Engineering GmbH. Schwingungsisolationssystem Mit Pneumatischemil. European Patent No.: filter Tiefpass EP1803970A2; 3. Integrated Dynamics Engineering GmbH. Air Bearing with Consideration of High-Frequency Resonances. US Patent Publication No.: US20080193061A1). The solution uses vertical and horizontal air bearings to decouple and isolate vibrations in all directions, which can achieve extremely low stiffness and natural frequency. The problems of this solution are: 1) In the disclosed technical solution, the vibration isolator cannot achieve precise positioning; 2) In the patent EP1803965A2, there is no degree of freedom of angular movement around the horizontal axis between the upper and lower mounting plates. The angular stiffness and natural frequency are very high; patents EP1803970A2 and US20080193061A1 use rubber blocks to provide angular freedom of rotation around the horizontal axis for the upper and lower mounting plates, but due to the high angular stiffness of the rubber blocks, the angular freedom of motion cannot be effectively achieved Degree of freedom decoupling, the friction between the components of the angular motion degree of freedom decoupling mechanism introduces additional stiffness, which restricts the vibration isolation performance.

Netherlands ASML company also proposed similar vibration isolator technical scheme (1.U.S.Philips Corp, ASM LithographyB.V. Pneumatic Support Device with A Controlled Gas Supply, and Lithographic Device Provided with Such A Support Device. U.S. Patent No.: US006144442A; 2 .Koninklijke Philips ElectronicsN.V.，ASM Lithography B.V.Lithographic Pneumatic Support Device with Controlled Gas Supply.国际专利公开号：WO99/22272；3.ASML Netherlands B.V.Support Device，LithographicApparatus，and Device Manufacturing MethodEmploying A Supporting Device，and A PositionControl System Arranged for Use in A Supporting Device.美国专利号：US007084956B2；4.ASML Netherlands B.V.Support Device，Lithographic Apparatus，and Device ManufacturingMethod Employing A Supporting Device and A Position Control System Arranged for Use in ASupporting Device.欧洲专利号：EP1486825A1 ). In patent US006144442A and WO99/22272, closed-loop feedback control is performed on the air source pressure to achieve the purpose of improving the stability and performance of the vibration isolator; in patent US007084956B2 and EP1486825A1, a vibration sensor is installed on the upper mounting plate, and a reference vibration system is introduced at the same time. The vibration isolation performance of the vibration isolator is improved through the control algorithm. However, the proposed technical solution still does not solve the problem of decoupling the precise positioning of the vibration isolator and the angular motion degrees of freedom of the upper and lower mounting plates.

Contents of the invention

The purpose of the present invention is to provide a double-layer gas isolator for the urgent requirements of ultra-precision measuring instruments and processing equipment, especially ultra-large-scale integrated circuit processing equipment such as step-scan lithography machines, for vibration isolators with low natural frequency and high positioning accuracy. Zero-stiffness vibration isolator with floating orthogonal decoupling and flexible membrane angle decoupling. The vibration isolator has three-dimensional ultra-low stiffness and ultra-low natural frequency. The upper and lower mounting plates can perform precise positioning and three-dimensional linear motion degrees of freedom. The full decoupling of angular motion degrees of freedom can effectively solve the problem of precision vibration isolation in ultra-precision measuring instruments and processing equipment, especially in step-and-scan lithography machines.

Technical solution of the present invention is:

A zero-stiffness vibration isolator with double-layer air flotation orthogonal decoupling and flexible membrane angle decoupling. Between the upper mounting plate and the lower mounting plate, the clean compressed air source is connected to the main body of the vibration isolator through the air pipe. Lubrication and support, the flexible membrane is installed on the upper end of the sleeve, and is pressed and sealed by the pressure ring. The upper and lower pressure plates of the pressure plate assembly are coaxially installed on the upper and lower surfaces of the flexible membrane, and the flexible membrane is clamped. The upper surface of the pressure plate is rigidly connected with the upper mounting plate, and the lower surface of the X-direction air-floating guide rail is rigidly connected with the air-floating plate. The lower surface is rigidly connected with the lower mounting plate, the air bearing plate and the lower mounting plate are lubricated and supported by the bearing air bearing surface in the Z direction, the air bearing plate and the Y direction air bearing guide rail are lubricated and guided by the air bearing surface of the Y guide rail; the Z direction voice coil motor , Z-direction displacement sensor and Z-direction limit switch are installed between the pressure plate assembly and the sleeve, X-direction voice coil motor, X-direction displacement sensor, and X-direction limit switch are installed between the sleeve and the air bearing plate, Y The voice coil motor in the Y direction, the displacement sensor in the Y direction, and the limit switch in the Y direction are installed between the air bearing plate and the lower mounting plate, the driving force direction of the Z direction voice coil motor is vertical, and the X direction voice coil motor and the Y direction sound The direction of the driving force of the coil motor is in the horizontal plane and perpendicular to each other, and the direction of the action line of the X, Y, Z direction displacement sensor and the X, Y, Z limit switch is consistent with the direction of the driving force of the X, Y, Z direction voice coil motor ; X, Y, Z direction displacement sensor and X, Y, Z direction limit switch are respectively connected with the signal input end of the controller, the signal output end of the controller is connected with the signal input end of the driver, and the signal output end of the driver is respectively connected with X, Y, Z direction voice coil motor connection.

The sleeve is provided with a gas pressure sensor, the sleeve is provided with an air inlet and a solenoid valve, the gas pressure sensor is connected to the signal input end of the controller, the signal output end of the controller is connected to the signal input end of the driver, and the driver The signal output terminal is connected with the solenoid valve.

The voice coil motors in the X, Y and Z directions are cylindrical voice coil motors or flat voice coil motors.

The X-direction air-floating guide rail and the Y-direction air-floating guide rail have a single guide rail structure or a double guide rail structure.

The X, Y, and Z direction displacement sensors are grating scales, magnetic scales, capacitive scales or linear potentiometers.

The X-, Y-, and Z-direction limit switches are mechanical limit switches, Hall-type limit switches or photoelectric limit switches.

The flexible membrane is a rubber membrane.

The gas pressure in the sleeve is 0.1MPa-0.8MPa.

The air film thickness of the axial bearing plane air bearing surface, the X direction guide air bearing surface, the Y guide guide air bearing surface and the Z direction bearing air bearing surface is 10 μm to 20 μm.

The diameter of the orifice on the plane air bearing surface on the sleeve is φ0.1mm˜φ1mm.

The technical innovation of the present invention and the good effect that produce are:

(1) The present invention adopts the axial bearing plane air bearing surface to isolate horizontal vibration, the air bearing surface has no friction, and the stiffness is approximately zero, so that the vibration isolator can obtain approximately zero stiffness in the horizontal direction and outstanding ultra-low frequency vibration isolation performance , which solves the problem that the horizontal stiffness of the vibration isolator is difficult to further reduce due to the limitations of structural stiffness and material properties in the prior art, and the problem that stiffness and stability cannot be balanced. This is one of the innovative points that the present invention is different from the prior art.

(2) The present invention adopts displacement sensors, limit switches, controllers, drivers, and voice coil motors to form a closed-loop feedback control system for vertical and horizontal positions to precisely control the relative position between the upper and lower mounting plates , the positioning accuracy can reach 10 μm level and above, which can effectively solve the problems of low positioning accuracy, positioning accuracy, stiffness, and vibration isolation performance of existing technical solutions. This is the second innovative point that the present invention is different from the prior art.

(3) The present invention uses double-layer orthogonal air-floating guide rails to decouple the degree of freedom of horizontal linear motion between the upper and lower mounting plates of the vibration isolator. The air-floating guide rails have no friction and wear, and do not introduce additional stiffness. The decoupling effect Good, it can make the vibration isolator obtain high positioning accuracy and zero stiffness characteristics in the horizontal direction; the use of flexible membranes to decouple the degree of freedom of angular motion, and the introduction of additional angular stiffness is small, which can effectively solve the existing technical solutions for decoupling with elastic bodies The problem of introducing large additional stiffness. This is the third innovative point that the present invention is different from the prior art.

(4) The present invention adopts a gas pressure sensor, a solenoid valve, a controller, and a driver to form a pressure closed-loop feedback control system, precisely controls the gas pressure in the sleeve to keep it constant, and performs gravity balance and compensation for the axial load of the vibration isolator , the stiffness of the flexible membrane near the equilibrium position is approximately zero, and the upper and lower pressure plates and the upper mounting plate that carry the load gravity can slide up and down with ultra-low stiffness, so as to achieve the ideal gravity compensation and zero stiffness vibration isolation effect. This is the fourth innovative point that the present invention is different from the prior art.

(5) The present invention uses an active actuator to actively control the relative position between the upper and lower mounting plates, and the parameters of the vibration isolator can be adjusted in real time according to the characteristics of the vibration-isolated object and the change of the working environment, so as to adapt to different working conditions and have the advantages of Better flexibility, adaptability and stability. This is the fifth innovative point that the present invention is different from the prior art.

Description of drawings

Figure 1 is a schematic structural diagram of a zero-stiffness vibration isolator with double-layer air bearing orthogonal decoupling and flexible membrane angle decoupling after the upper mounting plate is removed;

Figure 2 is a schematic cross-sectional structure diagram of a zero-stiffness vibration isolator with double-layer air bearing orthogonal decoupling and flexible membrane angle decoupling;

Fig. 3 is a schematic diagram of the air bearing surface of the axial bearing plane and the air bearing surface of the X guide rail;

Fig. 4 is a schematic diagram of the air bearing surface of the Y-direction rail and the bearing air bearing surface of the Z direction;

Fig. 5 is a schematic diagram of the sleeve structure;

Figure 6 is a block diagram of the control structure of the zero-stiffness vibration isolator with double-layer air bearing orthogonal decoupling and flexible membrane angle decoupling;

Fig. 7 is a schematic diagram of the orifice on the plane air bearing surface on the sleeve.

Part number description in the figure: 1 upper mounting plate, 2 lower mounting plate, 3 clean compressed air source, 4 vibration isolator main body, 5 flexible membrane, 6 sleeve, 7 pressure plate assembly, 7a upper pressure plate, 7b lower pressure plate, 8X Voice coil motor, 8a X-direction motor iron yoke, 8b X-direction motor magnet, 8c X-direction motor coil bobbin, 8d X-direction motor coil, 9Y-direction voice coil motor, 10Z-direction voice coil motor, 10a Z-direction motor iron yoke , 10bZ direction motor magnetic steel, 10cZ direction motor coil skeleton, 10dZ direction motor coil, 10eZ direction motor transition piece, 11X direction displacement sensor, 11a X direction grating reading head transition piece, 11b X direction grating reading head, 11c X direction glass grating Ruler, 12 Y direction displacement sensor, 13 Z direction displacement sensor, 13a Z direction grating reading head transition piece, 13b Z direction grating reading head, 13c Z direction glass grating ruler, 14X direction limit switch, 14a X direction limit block, 14b X direction Hall switch, 14c X-direction limit switch transition piece, 14dX-direction limit block transition piece, 15Y-direction limit switch, 16Z-direction limit switch, 16aZ-direction limit block, 16b Z-direction Hall switch, 16c Z-direction Limit switch transition piece, 17 gas pressure sensor, 18 solenoid valve, 19 controller, 20 driver, 21 axial bearing plane air bearing surface, 22 pressure ring, 23 air inlet, 24 plane air bearing surface orifice, 26 air pipe, 29X-direction air bearing guide rail, 30Y direction air bearing guide rail, 31X guide rail air bearing surface, 32Y guide rail air bearing surface, 33Z bearing air bearing surface, 34 air bearing plate.

Detailed ways

Specific embodiments of the present invention are given below in conjunction with the accompanying drawings.

A zero-stiffness vibration isolator with double-layer air flotation orthogonal decoupling and flexible membrane angle decoupling, consisting of an upper mounting plate 1, a lower mounting plate 2, a clean compressed air source 3, an air pipe 26 and a vibration isolator body 4, The vibration isolator main body 4 is installed between the upper mounting plate 1 and the lower mounting plate 2, and the clean compressed air source 3 is connected to the vibration isolator main body 4 through the air pipe 26. In the structure of the vibration isolator main body 4, the sleeve 6 The lower surface and the air bearing plate 34 are lubricated and supported by the axial bearing plane air bearing surface 21, the flexible membrane 5 is installed on the upper end of the sleeve 6, and is compressed and sealed by the pressure ring 22, the upper pressing plate 7a of the pressing plate assembly 7 is connected to the lower The pressure plate 7b is coaxially installed on the upper and lower surfaces of the flexible membrane 5, and clamps the flexible membrane 5. The upper surface of the upper pressure plate 7a is rigidly connected to the upper mounting plate 1, and the lower surface of the X-direction air bearing guide rail 29 is connected to the air bearing plate 34. Rigid connection, the sleeve 6 and the X-direction air bearing guide rail 29 are lubricated and guided through the X guide rail air bearing surface 31, the lower surface of the Y-direction air bearing guide rail 30 is rigidly connected to the lower mounting plate 2, and the air bearing plate 34 is connected to the lower mounting plate 2 Lubricated and supported by the bearing air bearing surface 33 in the Z direction, the air bearing plate 34 and the air bearing guide rail 30 in the Y direction are lubricated and guided by the air bearing surface 32 of the Y guide rail; the voice coil motor 10 in the Z direction, the displacement sensor 13 in the Z direction and the limit position in the Z direction The switch 16 is installed between the pressure plate assembly 7 and the sleeve 6, the X-direction voice coil motor 8, the X-direction displacement sensor 11, and the X-direction limit switch 14 are installed between the sleeve 6 and the air floating plate 34, and the Y-direction sound Coil motor 9, Y-direction displacement sensor 12, and Y-direction limit switch 15 are installed between the air bearing plate 34 and the lower mounting plate 2, the driving force direction of the Z-direction voice coil motor 10 is the vertical direction, and the direction of the X-direction voice coil motor The driving force directions of 8 and Y-direction voice coil motor 9 are in the horizontal plane and are perpendicular to each other, and the action lines of X, Y and Z-direction displacement sensors 11, 12 and 13 and X, Y and Z-direction limit switches 14, 15 and 16 The direction is consistent with the direction of the driving force of the voice coil motors 8, 9, 10 in the X, Y, and Z directions; the displacement sensors 11, 12, 13 in the X, Y, and Z directions and the limit switches 14, 15, 16 in the X, Y, and Z directions They are respectively connected to the signal input ends of the controller 19, the signal output ends of the controller 19 are connected to the signal input ends of the driver 20, and the signal output ends of the driver 20 are respectively connected to the X, Y, and Z direction voice coil motors 8, 9, 10 .

X, Y, and Z direction displacement sensors 11, 12, and 13 measure the displacement output by X, Y, and Z direction voice coil motors 8, 9, and 10, and X, Y, and Z direction limit switches 14, 15, and 16 are for X , Y, and Z direction voice coil motors 8,9,10 movement stroke limit; 16 feedback signals to control the X, Y, Z direction voice coil motors 8, 9, 10 to accurately control the relative position between the upper and lower mounting plates 1, 2.

Described sleeve 6 is provided with gas pressure sensor 17, and sleeve 6 is provided with air inlet 23 and electromagnetic valve 18, and gas pressure sensor 17 is connected with the signal input end of controller 19, and the signal output end of controller 19 is connected with The signal input end of the driver 20 is connected, and the signal output end of the driver 20 is connected with the solenoid valve 18 .

The voice coil motors 8, 9 and 10 in the X, Y and Z directions are cylindrical voice coil motors or flat voice coil motors.

The X-direction air-floating guide rail 29 and the Y-direction air-floating guide rail 30 have a single guide rail structure or a double guide rail structure.

The X, Y, Z direction displacement sensors 11, 12, 13 are grating scales, magnetic scales, capacitive scales or linear potentiometers.

The X, Y, and Z limit switches 14, 15, and 16 are mechanical limit switches, Hall-type limit switches or photoelectric limit switches.

The flexible membrane 5 is a rubber membrane.

The gas pressure in the sleeve 6 is 0.1MPa-0.8MPa.

The air film thickness of the axial bearing plane air bearing surface 21 , the X-direction guide air bearing surface 31 , the Y-direction guide air bearing surface 32 and the Z-direction bearing air bearing surface 33 is 10 μm to 20 μm.

The diameter of the orifice 24 on the plane air bearing surface on the sleeve 6 is φ0.1 mm˜φ1 mm.

An embodiment of the present invention is given below with reference to FIG. 1 to FIG. 6 . In this embodiment, when the vibration isolator is in operation, the lower mounting plate 2 is installed on the foundation, the base of the instrument or the foundation frame, and the upper mounting plate 1 is connected to the load to be vibration-isolated. Voice coil motors 8, 9, and 10 in X, Y, and Z directions all adopt cylindrical voice coil motors. Taking the X-direction voice coil motor 8 as an example, it mainly includes an X-direction motor iron yoke 8a, an X-direction motor magnet 8b, an X-direction motor coil skeleton 8c, and an X-direction motor coil 8d. The X-direction motor iron yoke 8a and the X-direction motor bobbin 8c are cylindrical, the X-direction motor magnet 8b is cylindrical, and the X-direction motor coil 8d is wound on the coil bobbin 8c. The X-direction motor iron yoke 8a and the X-direction motor magnetic steel 8b constitute the stator of the motor, and the X-direction motor coil skeleton 8c and the X-direction motor coil 8d constitute the mover of the motor. In the Z-direction voice coil motor 10, the Z-direction motor transition piece 10e provides the installation structure of the Z-direction motor coil skeleton 10c. When the motor is working, a current is passed through the coil. According to the electromagnetic theory, the energized coil will be affected by the voice coil force in the magnetic field. By controlling the magnitude and direction of the current, the magnitude and direction of the motor output driving force can be controlled.

In this embodiment, the installation method of the flexible film 5, the pressure ring 22 and the sleeve 6 is as follows: threaded holes are processed on the sleeve 6 along the circumferential direction, and through holes are processed on the pressure ring 22 and the flexible film 5 along the circumferential direction. The screw presses the pressure ring 22 against the flexible membrane 5 and assembles it on the sleeve 6, and utilizes the elasticity of the material of the flexible membrane 5 to play a role of sealing. The installation methods of the upper pressing plate 7a, the lower pressing plate 7b and the flexible membrane 5 are similar.

X, Y, and Z direction displacement sensors 11, 12, 13 adopt grating rulers. Taking the Z-direction displacement sensor 13 as an example, it mainly includes the Z-direction grating reading head transition piece 13a, the Z-direction grating reading head 13b, and the Z-direction glass grating scale 13c. The Z-direction grating reading head transition piece 13a provides Z-direction grating reading Mounting structure of the head 13b. When the grating ruler is working, the Z-direction grating reading head 13b can detect the relative displacement between it and the Z-direction glass grating ruler 13c, and send it to the controller 19 through the signal wire.

X, Y, Z direction limit switches 14, 15, 16 adopt Hall type limit switches. Taking the Z-direction limit switch 16 as an example, it mainly includes components such as a Z-direction limit block 16a, a Z-direction Hall switch 16b, and a Z-direction limit switch transition piece 16c. The two Z-direction Hall switches 16b are installed back to back, and the two Z-direction limit blocks 16a are made of metal materials, and are installed opposite to the sensitive end of the Z-direction Hall switch 16b. The Z-direction limit switch transition piece 16c provides a mounting structure for the Z-direction Hall switch 16b. When the limit switch is working, when the Z-direction Hall switch 16b is close to the Z-direction limit block 16a, the Z-direction Hall switch 16b gives a limit signal and sends it to the controller 19 through the signal wire.

In this embodiment, the Z-direction voice coil motor 10 , the Z-direction displacement sensor 13 and the Z-direction limit switch 16 are all installed inside the sleeve 6 .

The bearing of the vibration isolator to the load is realized in the following manner: the clean compressed air source 3 delivers clean compressed air to the sleeve 6 through the air pipe 26 , the electromagnetic valve 18 and the air inlet 23 . The controller 19 controls the opening of the solenoid valve 18 according to the feedback signal of the gas pressure sensor 17, and adjusts the gas flow rate input into the sleeve 6, thereby adjusting the pressure of the clean compressed air in the sleeve 6, so that the clean compressed air can be assembled on the pressure plate The upward force of the body 7 and the flexible membrane 5 is balanced with the gravity of the load and the pressing plate assembly 7, and other components loaded on the pressing plate assembly 7. At the equilibrium position of the flexible membrane 5 , the vertical stiffness of the flexible membrane 5 is approximately zero, while the lateral stiffness is very large relative to the lateral stiffness of the axial bearing air bearing surface 21 . Therefore, the sleeve 6 can move up and down in the vertical direction with approximately zero stiffness near the equilibrium position of the flexible membrane 5, thereby having outstanding ultra-low frequency vibration isolation performance.

In this embodiment, the pressure of the clean compressed air inside the sleeve 6 is 0.4 MPa, and the effective radius of the lower pressure plate 7b and the lower surface of the flexible membrane 5 is 100 mm, then the mass carried by a single vibration isolator is: m=p×πr ² / g≈1282kg, where p is the gas pressure, p=0.4MPa, r is the effective radius of the lower platen 7b and the lower surface of the flexible membrane 5, r=100mm, g is the acceleration of gravity, g=9.8m/s ² .

Figure 7 shows an embodiment of the orifice on the plane air bearing surface of the sleeve. In this embodiment, eight orifice holes 24 on the plane air-floating surface are uniformly distributed around the center of the circle on the lower surface of the sleeve 6 along the circumferential direction, with a diameter of φ0.2 mm.

Claims (10)

1. the Zero-rigidity vibration isolator of a double-layer air flotation crossing decoupling and the decoupling zero of flexible membrane angle, by upper mounting plate (1), lower installation board (2), clean compressed gas source (3), tracheae (26) and vibration isolator main body (4) composition, vibration isolator main body (4) is arranged between upper mounting plate (1) and lower installation board (2), clean compressed gas source (3) is connected with vibration isolator main body (4) by tracheae (26), it is characterized in that: in the structure of described vibration isolator main body (4), the lower surface of sleeve (6) and air supporting plate (34) are lubricated by axial carrying plane air bearing surface (21) and support, flexible membrane (5) is arranged on the upper end of sleeve (6), and compressed and sealing by trim ring (22), top board (7a) and the press table (7b) of pressing plate assembly (7) are coaxially arranged on the upper of flexible membrane (5), lower surface, and clamp flexible membrane (5), upper surface and the upper mounting plate (1) of top board (7a) are rigidly connected, X is rigidly connected to the lower surface of air-float guide rail (29) and air supporting plate (34), sleeve (6) is lubricated and guiding by X direction guiding rail air bearing surface (31) to air-float guide rail (29) with X, lower surface and the lower installation board (2) of Y-direction air-float guide rail (30) are rigidly connected, air supporting plate (34) and lower installation board (2) are lubricated by Z-direction bearing air-float face (33) and support, air supporting plate (34) is lubricated and guiding by Y-direction guide rail air bearing surface (32) with Y-direction air-float guide rail (30), Z-direction voice coil motor (10), Z-direction displacement transducer (13) and Z-direction limit switch (16) are arranged between pressing plate assembly (7) and sleeve (6), X is to voice coil motor (8), X is to displacement transducer (11), X is arranged between sleeve (6) and air supporting plate (34) to limit switch (14), Y-direction voice coil motor (9), Y-direction displacement transducer (12), Y-direction limit switch (15) is arranged between air supporting plate (34) and lower installation board (2), the driving force direction of Z-direction voice coil motor (10) is vertical direction, X is mutually vertical in horizontal plane to the driving force direction of voice coil motor (8) and Y-direction voice coil motor (9), X, Y, Z-direction displacement transducer (11, 12, 13) and X, Y, Z-direction limit switch (14, 15, 16) line of action direction and X, Y, Z-direction voice coil motor (8, 9, 10) driving force direction is consistent, X, Y, Z-direction displacement transducer (11,12,13) are connected with the signal input part of controller (19) respectively with X, Y, Z-direction limit switch (14,15,16), the signal output part of controller (19) is connected with the signal input part of driver (20), and the signal output part of driver (20) is connected with X, Y, Z-direction voice coil motor (8,9,10) respectively.

2. the Zero-rigidity vibration isolator of double-layer air flotation crossing decoupling according to claim 1 and the decoupling zero of flexible membrane angle, it is characterized in that: in described sleeve (6), be provided with gas pressure sensor (17), sleeve (6) is provided with suction port (23) and solenoid valve (18), gas pressure sensor (17) is connected with the signal input part of controller (19), the signal output part of controller (19) is connected with the signal input part of driver (20), and the signal output part of driver (20) is connected with solenoid valve (18).

3. the Zero-rigidity vibration isolator of double-layer air flotation crossing decoupling according to claim 1 and the decoupling zero of flexible membrane angle, is characterized in that: described X, Y, Z-direction voice coil motor (8,9,10) are cylinder type voice coil motor or plate voice coil motor.

4. the Zero-rigidity vibration isolator of double-layer air flotation crossing decoupling according to claim 1 and the decoupling zero of flexible membrane angle, is characterized in that: described X is single rail structure or two guide rail structure to air-float guide rail (29) and Y-direction air-float guide rail (30).

5. the Zero-rigidity vibration isolator of double-layer air flotation crossing decoupling according to claim 1 and the decoupling zero of flexible membrane angle, is characterized in that: described X, Y, Z-direction displacement transducer (11,12,13) are grating scale, magnetic railings ruler, appearance grid chi or linear potentiometer.

6. the Zero-rigidity vibration isolator of double-layer air flotation crossing decoupling according to claim 1 and the decoupling zero of flexible membrane angle, is characterized in that: described X, Y, Z-direction limit switch (14,15,16) are mechanical type limit switch, Hall-type limit switch or photoelectric limit switch.

7. the Zero-rigidity vibration isolator of double-layer air flotation crossing decoupling according to claim 1 and the decoupling zero of flexible membrane angle, is characterized in that: described flexible membrane (5) is rubber membrane.

8. the Zero-rigidity vibration isolator of double-layer air flotation crossing decoupling according to claim 1 and the decoupling zero of flexible membrane angle, is characterized in that: described sleeve (6) interior gas pressure is 0.1MPa ~ 0.8MPa.

9. the Zero-rigidity vibration isolator of double-layer air flotation crossing decoupling according to claim 1 and the decoupling zero of flexible membrane angle, is characterized in that: the air-film thickness in described axial carrying plane air bearing surface (21), X direction guiding rail air bearing surface (31), Y-direction guide rail air bearing surface (32) and Z-direction bearing air-float face (33) is 10 μm ~ 20 μm.

10. the Zero-rigidity vibration isolator of double-layer air flotation crossing decoupling according to claim 1 and the decoupling zero of flexible membrane angle, is characterized in that: the diameter of the plane air bearing surface throttle orifice (24) on described sleeve (6) is φ 0.1mm ~ φ 1mm.