Abstract
This thesis designed, fabricated, and tested a linear stage equipped with hydrostatic bearings. We verified the theory by applying it with capillary restrictor and theoretically investigated its characteristics when it was equipped with a novel pressure self-sensing compensating restrictor. The restrictor features an elastic element that deforms in response of the pressure variation of the oil chamber. It results in the change of the flow resistance of the restrictor, therefore, achieves the function of self-sensing compensation. Since the design integrates the restrictor with the bearing pad, it possesses the advantages of high load capacity, stiffness, and damping, in addition to fewer components, easy manufacturing and assembly, less cost. This study started with construction of theoretical models of the hydrostatic bearings installed with capillary and the novel self-regulating restrictors, respectively. The equations governing the load capacity and stiffness of these two-types of bearings with opposed pads, respectively, were derived. Then, the stiffness equation of the bearing system with multiple pads (oil chambers) was developed; we also simulated the stiffness relationship between discrete pocket and the whole system. The simulation results confirm the vector additive characteristic of the stiffness of multiple-pad bearing system. This study also performed static analyses of closed-type hydrostatic slideway bearings installed with either a capillary or a self-sensing compensating restrictor. Furthermore, this study designed and fabricated a linear motor actuating, linear scales back feeding linear stage with the two-types of restrictors based on the desired load capacity and stiffness. Then, we study the error-averaging effect of the oil film on the hydrostatic slideway vertical straightness, in the half-wave and full-wave type surface form errors in order to gain the finest error-averaging parameter. The load capacity and stiffness of the closed-type linear systems were verified, first, with the numerical simulation, then, confirmed with experiments. The error motion of the hydrostatic slideway was also measured