Abstract
This thesis designed, fabricated, and tested a novel pressure self-sensing compensating restrictor and applied it to a linear stage equipped with hydrostatic bearings. 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 single pad and opposed pads, respectively, were derived. Then, the stiffness equation of the bearing system with multiple pads (oil chambers) was developed. The simulation results confirm the vector additive characteristic of the stiffness of multiple-pad bearing system. This study also performed dynamic analyses of opposed-pad hydrostatic bearings installed with either a capillary or a self-sensing compensating restrictor. Furthermore, this study designed and fabricated a hydrostatic bearing linear stage with the two-types of restrictors based on the desired load capacity and stiffness. The load capacity and stiffness of the single-pad and opposed-pad bearing systems were verified, first, with the numerical simulation. Then, the vector additive characteristic of the stiffness of multiple-pad bearing system was, then, confirmed. Experimental results revealed that the proposed restrictor became invalid at the beginning of pressurization stage due to the unequal gaps of the two opposed pads. This involves with the transient behavior of the elastic element of the restrictor. A restrictor with gap self-adjusting and high damping characteristics may be required in the future.