AN EVALUATION OF THE STIFFNESS OF A HYDROSTATIC SPINDLE UNIT WITH EXTREME VALUES BASED ON NUMERICAL SIMULATION

Abstract

The external circular grinding machine is a finishing machine tool which is
commonly used in the machining industry. The precision of the grinding workpiece
depends mainly on the accuracy and the working quality of the spindle unit of
machine tools, in which the stiffness of the spindle bearing unit plays an important
role. This writing presents a simulation study on effects of hydrostatic parameters
with the extreme values of a hydrostatic spindle unit of an external circular grinding
machine on the bearing stiffness. With the calculation method, the selected
pressureregion, and the machining ability with the litmit clearance changing from
15 to 22.5µm, the stiffness of the hydrostatic spindle unit is unsatisfactory with
several pump pressure values. However, in the range of pumping pressure from 2 -
5MPa, the ratio β is decisive to the stiffness, it is possible to choose a bearing
diameter that is most suitable with the design requirements.