Dynamic Behaviors of a Circular Worktable Mounted on Closed-Type Hydrostatic Thrust Bearing Compensated by Constant Compensations

Abstract

This study investigates the influences of constant compensations which are produced by capillary or constant flow pump on the dynamic characteristics of a circular worktable supported by a closed-type hydrostatic thrust bearing. The dynamic behaviors of this worktable are analyzed by using Runge-Kutta method to solve the coupled motion equation of worktable and pressure equations of hydrostatic film flow. For various supply pressure parameters, external loads, and varieties of design parameters, the dynamic responses of worktable subjected to both external excitations of harmonic force and step force are simulated, respectively. The results reveal the influences of both constant compensations on the dynamic characteristics of hydrostatic bearing by the different responses of worktable and make the appropriate parameters of design can be found for the worktable-bearing system. The accomplishments of this study will help the designers who deal with the hydrostatic- bearing compensated by constant restrictions to select the design parameters to approach the optimum condition.

A review of hydrostatic bearing system: Researches and applications

“…BMA Maher 38 proposed an ellipse-shaped thrust bearing and compared its load-carrying capacity with circular and rectangular oil pads. Y Kang et al 39 carried out a comparative research of closed-type thrust bearing supplied by constant oil pump and compensated by capillary restrictor. Figure 17 shows the oil supply model of closed-type thrust bearing.…”

“…There are four common types of oil supply method: constant oil pump, capillary restrictor, membrane restrictor, and orifice restrictor. Y Kang et al 39 provided the model of capillary restrictor and constant oil pump in Figure 17(a) and (b). M Gohara et al 40 presented a membrane restrictor in their research in Figure 45.…”

“…Model of closed-type hydrostatic thrust bearing:39 (a) capillary restrictors and (b) constant flow pumps.…”

Evaluation Damping Performance for Hydrostatic Bearing Film by Damping Ratio Scaling

“…Lund [1965], Ghosh et al [1979], Rowe and Chong [1986] evaluated stiffness and damping coefficients of hybrid journal bearings by solving dynamic Reynolds equation. Wang and Cusano [1991], and Kang et al [2013] studied the dynamics of the worktable supported by closed-type hydrostatic bearing which behaves overdamped in single degree of freedom. However, they didn't determine the damping coefficient or damping ratio of bearing film.…”

Identification of Characteristic Parameters for Hydrostatic Bearings

“…Sharma et al [14] utilized finite element method to analyze the thrust bearings of four shapes in comparisons of the static characteristics. Kang et al [15] investigated the influences of constant compensations on the dynamic characteristics of a circular worktable supported by a closed-type hydrostatic thrust bearing.…”