2015 年 81 巻 6 号 p. 576-581
Hydrostatic bearing is often employed as a guideway of grinder for cam shaft and crank shaft, which are required to achieve both of high accuracy and high productivity. Reduction of bearing pocket is effective in driving down manufacturing cost of the guideway. In this research, hydrostatic bearing with self-controlled restrictor is proposed to achieve demand performance by less bearing pockets than those of conventional guideway with orifice restrictor. A self-controlled restrictor with a diaphragm improves static stiffness of the proposed bearing. Dynamic stiffness and step response are calculated by numerical analysis based on Reynolds equation, which considers non-linearity of oil flow at restrictor, elastic deformation of plumbing and volumetric strain of air bubble in oil. The analysis results have revealed that the important parameters for static stiffness of hydrostatic bearing would be the gap of the diaphragm restrictor, thickness of diaphragm and supplied pressure of bearing oil. Dynamic stiffness depends on air amount in oil and length of plumbing. The developed bearing has achieved three times higher stiffness in static response than that of the conventional bearing with orifice restrictor. Dynamic stiffness has also improved at the range of low frequency.
