Abstract
In order to realize the most accurate positioning in bearing systems, two methods have been mainly proposed. One is holding the table in a constant position by using a controlled piezoelectric actuator which reacts to the change of gas film thickness. The other is by changing the flow rate through restrictors. This paper describes these controlled shaft trangent response characteristics under impulse forces in hydrostatic circular thrust gas bearings with a central pocket. Following conclusions are obtained : (1) The shaft convergent characteristics are good in both methods if there is no phase-lag in control systems, etc. (2) The shaft under self-excited vibrations can be better stabilized by the latter method. (3) The phase-lag in control systems in the former method, greatly affecting the shaft convergence characteristics, should be less than about 1/50 of a natural period time of gas bearing systems.
