Abstract
To realize an infinite-stiffness aerostatic bearing, a new type of active restrictor is proposed. The proposed restrictor controls the air volume exhausted from the bearing surface. Therefore, the restrictor is called an exhaust control restrictor (ECR). Conventional active restrictors should be placed very close to the bearing surface for suppressing pneumatic hammer. Without the occurrence of pneumatic hammer, the ECR can be placed apart from the bearing surface. Consequently, the limitation for the design of an aerostatic bearing with the ECR is much less than that of with conventional active restrictors. The ECR is incorporated into an aerostatic radial bearing. The displacement of the bearing shaft is detected by an electric micrometer, and fed back to a micro computer. The micro computer controls a piezoelectric actuator which changes the restriction gap of the ECR. Radial load is applied to the bearing shaft, however, the ECR suppresses the displacement of the shaft. Thus, it is shown that the bearing stiffness can be infinite.
