Key Techniques of Ultra-Precision Aerostatic System

In the process of ultra-precision machining and measuring, nanoscale rotary and linear motion can be realized by aerostatic system. Aerostatic restrictors are one of core components in aerostatic system. An aerostatic restrictor with multi-micro channels was designed and developed, combined with the orifice and torus throttling methods. Besides, the mentioned restrictor has two individual parts assembled together by interference fit, which can alleviating the contradiction between its stiffness and stability. Its maximum bearing capacity was 708.4N when the supply gas pressure was 0.5MPa. Numerical simulation and experimental investigation indicates the pressure in gas film of this restrictor gradually reduces to atmospheric pressure from the center to the surrounding. The temperature decreases from the outlet to the edge and the maximum temperature difference is more than 5 degrees C, which verifies Joule-Thomson effect in the throttling process. In order to reduce the influence of gas source fluctuation on the parameters such as gas film thickness, pressure and temperature, high accuracy stable pressure source was developed applying two-stage series closed-loops feedback control, which can make the outlet pressure error below 1%. Because of the influence of ambient noise on ultra-precision aerostatic system, high precision vibration-isolation platform was developed applying air spring vibration-isolation technology, whose natural frequency can be as low as 1.22Hz.