Inclination angle effect of tribological performance for hydrostatic bearing having tilting oil pad under variable viscosity conditions

Abstract

In order to improve tribological performance of hydrostatic bearing, an innovative hydrostatic bearing structure having tilting oil pad is designed. During the operation, the semicircular boss at the bottom of the oil pad can realize the circumferential micro-motion. It generates additional dynamic pressure, and forms the static and dynamic pressure mixing support, make up for the static pressure loss, and solves the problems such as low precision and unstable operation of the numerical control equipment under the high speed and heavy load conditions. According to the tribological principle and lubrication theory, bearing capacity, flow rate, oil film thickness equation and oil film stiffness for hydrostatic and dynamic hybrid bearing are derived under variable viscosity conditions. The simulation model of hydrostatic bearing having tilting oil pad is established. ANSYS software is used to analyze the distribution of oil film temperature field and oil film pressure field under different inclination angles. The effects of tilting oil pad inclination angle on oil film tribological performance and oil film stiffness are obtained. The results show that the hydrostatic bearing having tilting oil pad can generate additional dynamic pressure in high speed operation, make up the loss of static pressure. When the inclination angle is 0.0044°, oil film temperature rise is 34.8 ℃, the average pressure is 622.2 KPa, oil film stiffness is 54104 N/µm, the comprehensive lubrication performance is optimal, the oil film stiffness is the largest, and the operation accuracy and stability of hydrostatic bearing are improved.