Oil pressure and viscosity influence on stiffness of the hydrostatic spindle bearing of a medium-sized circular grinding machine

Abstract

In surface finishing of a grinding machine, the dimension accuracy of the workpiece is most affected by the stiffness of the spindle. For the hydrostatic spindle of a medium-sized circular grinding machine, the primary factors affecting the oil film stiffness are bearing structure parameters, lubrication characteristics, and working conditions. In this study, the effects of lubricant pressure and oil viscosity on the stiffness of the hydrostatic spindle based on the working conditions were investigated. The oil viscosity affects the spindle by increasing the stiffness that corresponds to the increase in viscosity in the range of 0.001–0.002 Pa[Formula: see text]S, while the stiffness proportionally increases with pump pressure changing in the range of 3–5 MPa. Experimental results also indicate that based on the stiffness of the bearing, a viscosity of 0.002 Pa[Formula: see text]S, pump pressure of 5 MPa, and load range of 500–1000 N are the most feasible working conditions for hydrostatic spindle associated with the fine-machining process on a medium-sized external grinding machine.