Design for static stiffness of hydrostatic bearings: double-action variable compensation of spool-type restrictors

Abstract

Purpose – This paper is the third part of a serial studies for constant and variable compensations of the closed-type hydrostatic thrust bearings which has face-to-face recesses couple. The static stiffness of closed-type hydrostatic thrust bearings can then be obtained from the differentiation of recess pressure with respect to worktable displacement. The paper aims to discuss these issues. Design/methodology/approach – In this paper, the double-action restrictors of cylindrical-spool-type and tapered-spool-type are taken into consideration for variable compensation of hydrostatic bearings. Findings – The static stiffness in thrust direction of hydrostatic bearing is determined by the flow continuity equations that are formulated by film flow and compensation flow for each recess, respectively. The type selection and parameter determination of the double-action spool-type restrictors can be obtained from finding results of this study for maximum stiffness in design of hydrostatic bearings. Originality/value – This study reveals that the appropriate range of recess pressure ratio and design parameters of restrictors for the maximum stiffness can be obtained, the avoidance of negative stiffness is also provided.