Error correction in hydrostatic spindles by optimal bearing tuning

摘要

In this paper a high precision grinding wheel is considered as a rigid rotor mounted on two hydrostatic bearings. The equations for small perturbations of the wheel on the bearings are derived in the form of a multi-input multi-output transfer function matrix enabling the frequency response function of the wheel to be determined. Using direct search optimisation methods the optimal stiffness and damping of the bearings is computed. The dynamic characteristics of the bearings tuned for minimum radial displacement of the spindle is achieved maximising thereby the accuracy of the grinding process. Simulation results show that by stiffness coarse adjustment and fine adjustment of the damping in the bearings a spindle with 35 μm manufacturing error can produce components with 3 μm accuracy.