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.

Investigations in Hydrostatic Planar Bearings Compensated by Tapered-Spool Restrictors I: Flow Rate

“…The rate of flow passing through the tapered space between conical spool and cylindrical sleeve for SATS restrictors have the similar forms of DATS restrictors, which presented by Bassani [5] and Kang et al [7], but replacing pressure difference by recess pressure and described by…”

“…Their determinations were based on that the hydraulic resistances of pad film and compensator are combined in series. Additional materials and more details for hydrostatic planar bearings using single-action variable compensations was presented by Kang et al [6] and using double-action variable compensation as shown in Kang et al [7]. Although these articles have studied in issues of the tapered-spool restrictors used in hydrostatic bearing, but the influence of design parameter on static and dynamic characteristics of this type restrictors hasn't been addressed sufficiently.…”

Investigations in Hydrostatic Planar Bearings Compensated by Tapered-Spool Restrictors II: Load Capacity and Static Stiffness

“…[7] variable compensations for spool-type compensation were presented. They have compared static characteristics of cylinder-spool and taperedspool to reveal that the latter is superior to the former.…”

An improved lumped parameter method for calculating static characteristics of multi-recess hydrostatic journal bearings

“…Kang et al. 15 studied the static stiffness of a closed-type hydrostatic thrust bearing compensated by double-action spool-type restrictors using the LPM. They gave the proposed design parameters for reaching maximum stiffness.…”

“…Kang et al 14 utilized the LPM to determine the variations of film thickness with respect to the recess pressure for both open-type and closed-type hydrostatic flat bearings with single-action variable compensations. Kang et al 15 studied the static stiffness of a closed-type hydrostatic thrust bearing compensated by double-action spool-type restrictors using the LPM. They gave the proposed design parameters for reaching maximum stiffness.…”