Physically based modeling method for comprehensive thermally induced errors of CNC machining centers

Abstract

The advantages of PBM (physically based model) over DDM (data-driven model) were presented, and physically based modeling of comprehensive thermal errors of servo axis and spindle was proposed. Based on the theory of frictional heat, heat convection, and heat conduction, the model for thermal error of servo axis was established, and the screw temperature field at any time can be obtained to predict screw thermal error. The thermal bending deformations of spindles were analyzed for a C-type vertical machining center. The models for spindle radial thermal drift error under different deformations were established, and the criterion for determining the deformations was presented. Tests for identifying parameters of the suggested models were carried out on a TC500R vertical machining center. The compensation effects were verified using both experiment and machining. The results indicated that the suggested PBM results in high accuracy and strong robustness, even if the moving state of servo axis and the rotating speed of spindle randomly changed.