Precision press fit assembly using micro actuator

摘要

To accurately locate a fluid dynamic bearing element along a shaft, the shaft is excited at or near its resonant frequency while applying a press force to the shaft, and holding the bearing element still. The assembly process then becomes a dynamic process, with the result that the positioning or locating of the shaft relative to the cone or other bearing element can be achieved with much greater accuracy. A PZT (piezoelectric) element may be located between the press and the motor shaft with the frequency of the PZT element being a function chosen to effectively oscillate the shaft at or near its resonant frequency; thus the PZT element should be excited at the approximate axial resonant frequency of the shaft. The press structure which is used to apply the press force should have sufficient stiffness so as not to absorb the energy created by the PZT element, which would damp its effects.