Design And Characteristic Analysis Of Hydrostatic Bearing Used On High-Speed Crankshaft Grinder

Hydrostatic bearing, with its characteristics of low friction power consumption, great burden capacity, high bearing stiffness and stabilization, is widely applied in high-end manufacturing equipment. According to the concrete job requirements of high-speed CBN grinding for crankshaft, this paper has improved the original spindle support from the rolling bearing to hydrostatic bearing, and carried on design and simulation studies into hydrostatic bearings.Firstly, the basic structure and working principle of hydrostatic bearing have been introduced in this paper. And on the basis of analysis of grinding characteristics in the high-speed CBN crankshaft grinding, the main performance index and design requirements of the hydrostatic bearing are described. The general structure of hydrostatic bearing, and concrete structure parameters of the spindle bearing are designed.Secondly, according to the lubrication mechanism of hydrostatic bearing, the hydrostatic bearing mathematical model is established. Considering the cavitation effect when bearing run in high speed, the cavitation model is established based on modified Elrod cavitation model, which is benefit for the calculation process of oil film pressure. The generalized equation that integrates the full film region and cavitation region based on JFO boundary condition is derived, which provides a more accurate calculation method. Using the finite different method, the hydrostatic bearing of hole restrictor oil film pressure distribution is calculated by the Reynolds equation and flow equilibrium equations, then the bearing’s oil film stiffness and damping is obtained.Thirdly, oil film carrying capacity, stiffness and damping are calculated under different spindle eccentricity, different speed, different throttle coefficient and different bearing length-width ratio with MATLAB. And the influence they have made on the stability of spindle system and crankshaft grinding accuracy is analyzed.Finally, the impact oil film’s temperature variation have on bearing performance is analyzed when hydrostatic bearing run in high speed. Through the establishment of three-dimensional geometric model of bearing oil film, the impact of spindle speed and oil supple pressure on bearing oil film temperature distribution is calculated with FLUENT. On the basis of the analysis of oil film temperature distribution, a new type of hydrostatic bearing cooling system is designed.