2016 年 82 巻 10 号 p. 894-900
Hydrostatic bearing is often employed as a journal bearing of grinding wheel spindle for achievement of high accuracy. For the realization of a compact and inexpensive bearing, reduction in number of pockets is an effective way. To maintain performance of a hydrostatic bearing with fewer pockets than that of the conventional one, it is essential to improve static stiffness per a pocket. A self-controlled restrictor with a diaphragm improves static stiffness of the proposed hydrostatic bearing. In this research, a compact headstock using hydrostatic bearing with a self-controlled restrictor is proposed. Numerical analysis of dynamic stiffness and static stiffness of the proposed bearing is carried out by using Reynolds equation, which considers non-linearity of oil flow at restrictor, elastic deformation of plumbing and volumetric strain of air bubble in oil. By experimental evaluation of static stiffness and dynamic response, the developed headstock has demonstrated higher performance than that of one using orifice restrictor. In comparison with a conventional headstock using ball bearing, the proposed headstock has achieved one-half of total length and higher grinding accuracy.
