2014 Volume 45 Issue 1 Pages 8-14
The aim of this research is to establish a quick and robust rotation control method for the air turbine spindle used in ultra-precision machining. In ultra-precision machine tool, such as an aspherical lens generator, air turbine spindles with aerostatic bearing are widely used due to their beneficial properties, such as high precision, high speed, low friction, and low vibration. Nevertheless, when a disturbance force (e.g., cutting force) is given to the spindle, the rotation speed of the spindle tends to decrease. Because methods of controlling the air supply pressure and the flow rate are not sufficiently precise and quick, it has been impossible to control the rotation speed and the output torque of the air turbine spindle. To solve these problems, in this research, we developed a high-precision quick-response pneumatic pressure regulator and applied it to the rotation feedback control of an air turbine spindle. We also set a disturbance force observer in the feedback control system, in order to avoid rotation speed change caused by the disturbance force given to the air turbine spindle. By simulation and experiment, the effectiveness of the proposed method is evaluated.
