Comprehensive thermal growth compensation method of spindle and servo axis error on a vertical drilling center

This paper deals with the modeling of comprehensive thermal growth of spindle and servo axis. Thermal errors of a vertical drilling center TC500 were measured using a spindle error analyzer and a laser interferometer, thermal error of servo axis was decomposed, and each term analyzed. Spindle thermal growth model based on temperature variation including an identification method for the parameters of the suggested model was presented. Similarly, the servo axis models for thermal expansion error (TEE) in the stroke range and the thermal drift error (TDE) of origin were derived based on heat-transfer mechanism, and the parameter identification method was presented. The experimental results indicate that by applying the proposed model, high accuracy stability can be achieved, even when the moving state changes randomly. A specific machining process of the upper surface of a rectangular workpiece was designed to verify the effects of error compensation to the unaided eye. The machining results indicate that the proposed model has high accuracy and strong robustness in compensating the comprehensive thermal error.