High performance hydrostatic bearing using a variable inherent restrictor with a thin metal plate

Demands for machining of hard-to-cut materials have increased in a variety of industries. In order to meet such demands, high performance guideways are required for machine tools. In this study, in order to realize a bearing with high dynamic and static stiffness, a hydrostatic bearing using a variable inherent restrictor with a thin metal plate is newly proposed. The thin metal plate deforms elastically according to the pressure difference of working oil between both sides of the thin metal plate. Consequently, the deformation compensates the bearing clearance by adjusting the inherent restrictor. Modeling and numerical analysis of the proposed bearing were conducted, and the results confirmed that the bearing stiffness and response characteristics can be improved and then the oil flow can be reduced by applying the inherent restrictor with a thin metal plate. Furthermore, an experimental set-up for evaluating the bearing property was constructed and the load capability, static stiffness, dynamic stiffness, flow characteristic, and response characteristic of the bearing with the thin metal plate were compared with that of the bearing without the thin metal plate. The evaluation results of static performance confirmed that the flow rate of the bearing with the thin metal plate becomes lower as compared with that of the bearing without the thin metal plate, because the thin metal plate is acting as a fluid restrictor. In addition, the evaluation results of dynamic performance confirmed that the dynamic stiffness and the time response of the bearing were greatly improved by applying a variable inherent restrictor. These results confirmed that a high performance hydrostatic bearing can be realized by applying the proposed bearing.