Abstract
Machining accuracy of ultra-precision machine tools relies on the performances of its spindle. In particular, high bearing stiffness is important to minimize the displacement due to cutting forces. For this reason, the high stiffness water hydrostatic spindle was developed and its hydrostatic bearing was designed to achieve the stiffness of 1000 N/μm. However, the measured result of its bearing stiffness is lower than the design value. This may be caused by a change in the bearing gap due to deformation of the spindle by water pressure. Thus, this study proposes the design method to introduce the suitable gap size based on a consideration of the spindle deformation due to the water pressure. As the results of this study, it is confirmed that the modified gap of the spindle can achieve objective bearing stiffness. This paper describes measured result of the bearing stiffness with the modified gap of the spindle.
