Analysis and experimental verification of dynamic characteristics of air spindle considering varying stiffness and damping of radial bearings

摘要

The dynamics of a radial bearing and aerostatic spindle system in an ultraprecision fly-cutting machine cause mid-spatial waviness errors, which have a significant effect on surface topographies. Air bearings, which are externally pressurized, comprise two journal bearings and two thrust bearings with orifice restrictors. The dynamic coefficients of the radial bearings are obtained by adopting the perturbation and finite difference methods with the MATLAB (R) software. In addition, the influences of the spindle speed and tilt angle on the dynamics of the radial bearings are investigated in detail. The simulation results show that the rotating speed has a little impact on stiffness but having a great impact on damping, and the theoretical values of static stiffness are almost the same as the experimental values. The dynamic responses of the spindle system supported by pressurized air film are obtained, and the simulation analysis of spindle responses under cutting forces is also well matched to the experiment results.