Research On Thermal Errors Of High Speed Motorized Spindle Of 5-Axis CNC Machine Tools

In actual application, heat generated by high speed motorized spindle is the main factor to affect the machining precision of 5-axis CNC machine tools, which largely limits the machining precision from improvement. Statistics show that errors induced by heat are up to 70% of the total machining errors. Therefore, to improve accuracy of CNC machine tools, effective method must be applied to analyze and decrease thermal errors.Based on the need, the model of thermal error of 5-axis CNC machine tools is built, which supplies foundation for practice, and predicts, controls and compensates thermal errors of CNC machine tools effectively. The main research content in the thesis is below:(1) The model of thermal error for spindle is built by basic theory in heat transfer, and the expression of thermal error is deduced.(2) A complex structure of the XH714-5X machine tools is simplified with the multi-body theory.(3) Thermal errors of 5-axis CNC machine tools are analyzed based on the theories of homogeneous coordinate transformation and differential motion in robotics, and the transformation matrixes between the coordinate system of kinematic pairs and the relationship between errors and compensations are obtained.(4) The compensation program for thermal error of high speed motorized spindle is got, which takes advantage of differential capacitance sensor to measure thermal errors, and puts forward a specific compensation method in practice.Twenty figures, three tables and seventy-nine references.