Abstract
The following deals with the static and dynamic specification of the motor integrated spindle. This spindle unit has a fixed position and constant pressure preload switching mechanism operated using hydraulic pressure. With respect to the static specification, measurement of the static rigidity and natural frequency confirms that preload switching occurs. The performance of the rotating spindle was evaluated using a fixed position preload for low speeds provided high rigidity, while using a constant pressure preload provided sufficient high speed performance. A bench test was carried out to evaluate temperature and runout characteristics and further tests were performed in an actual machining process. Both tests showed that the switching of the spindle's preload provided sufficient performance.
