Error correction in hydrostatic spindles by optimal bearing tuning

In this paper a high precision grinding wheel is considered as a rigid roto r mounted on two hydrostatic bearings. The equations for small perturbation s of the wheel on the bearings are derived in the form of a multi-input, mu lti-output transfer function matrix, enabling the frequency response functi on of the wheel to be determined. Thereafter an optimisation algorithm is p roposed which considers speed, load and dimensions of the spindle, and comp utes optimal stiffness and damping of the bearings. The dynamic characteris tics of the bearings, tuned for minimum radial displacement of the spindle, is achieved maximising thereby the accuracy of the grinding process. Simul ation results show that by stiffness coarse adjustment, and fine adjustment of the damping in the bearings, a spindle with 35 mu m manufacturing error , can produce components with 3 mu m accuracy. (C) 2000 Published by Elsevi er Science Ltd. All rights reserved.