Thermal behavior analysis of horizontal CNC lathe spindle and compensation for radial thermal drift error

At present, the thermal deformation law of the horizontal CNC lathe spindle has not been observed, whereas no effective model for the radial thermal drift error for the CNC lathe spindle exists. In order to solve these problems, the thermal deformation of the spindle was investigated on a CNC lathe, and the temperatures along with the radial thermal drift errors of various rotation speeds were obtained. Based on the test result analysis, the radial thermal drift error mechanism and the complete thermal deformation during the warmup and cooldown phases were expounded. The “Liu-loop” of the spindle was drawn, and the corresponding two basic characteristics were described. Ten types of spindle thermal deformations are listed, and the relationship between the radial thermal drift error and the temperatures of the key points was established by a physically based modeling method. The criteria for the spindle thermal determination and the compensation value expression for the workpieces with various lengths were given. Finally, the effectiveness of the proposed model was proved by simulations and experiments.