Eddy current damping zero-stiffness vibration isolator for air floatation ball bearing angle decoupling

Abstract

The invention relates to an eddy current damping zero-stiffness vibration isolator for air floatation ball bearing angle decoupling and belongs to the technical field of precise vibration isolation. A sleeve and a lower installation board of a vibration isolator main body are lubricated and supported by an air floatation surface, and a piston barrel and the sleeve are lubricated and supported by the air floatation surface. An eddy current damper is used for attenuating vibration energy and improving positioning stability. The angle motion freedom between an upper installation board and the lower installation board is decoupled through an air floatation ball bearing. A voice coil motor, a displacement sensor, a limit switch, a controller and a driver form a position closed-loop feedback control system which accurately controls the relative positions of the upper installation board and the lower installation board. The eddy current damping zero-stiffness vibration isolator has the characteristics of three-dimensional zero-stiffness, high positioning accuracy and angle decoupling, can obtain ultra-low inherent frequency and highlighted low frequency / ultra-low frequency vibration isolation performance, and accordingly effectively solves the problem of high-performance vibration isolation of ultra precise measurement instruments and processing devices, especially stepping scanning photo-etching machines.

Description

technical field [0001] The invention belongs to the technical field of precision vibration isolation, and mainly relates to an eddy current damping zero stiffness vibration isolator with angle decoupling of an air-floating ball bearing. Background technique [0002] 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. Especially the ultra-large-scale integrated circuit processing equipment represented by the step-scan lithography machine has extremely high technical intensity and complexity, 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-sc...

AI Technical Summary

Problems solved by technology

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-film resonance, and poor stability

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 decoupling, the friction between the decoupling mechanism components of the angular motion freedom introduces additional stiffness, which restricts the vibration isolation performance

However, the proposed technical solution still does not solve the problem of decoupling the precise positioning of the vibration isolator and the angular motion freedom of the upper and lower mounting plates.

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