Thermal error detection and compensation technology for spindle of horizontal CNC machine tool with large torque

Abstract

Titanium alloys and other difficult-to-machine materials are machined using large-torque CNC machine tools, and asymmetric mechanical spindle is employed in its spindle system. The mechanical spindle demonstrates high power and large torque. The asymmetric design makes the spindle structure more compact while reducing assembly requirements. Nevertheless, when processed, the asymmetric spindle shows complex thermal characteristics and makes it difficult to ensure real-time control, which easily results in significant errors for parts. To eliminate the uncontrollable thermal error, the efforts are made as follows. Firstly, the cold state and hot state attributes in thermal error analysis of mechanical spindle are defined, and the method to distribute the measuring position of asymmetric mechanical spindle temperature is proposed. Secondly, a three-dimensional space detection and analysis method for thermal error of six-vector eight-test based on rotation error vector and deviation error vector is suggested. Thirdly, according to the experimental results, the six-vector thermal error of the three-dimensional space is determined, and then a thermal error compensation technology based on Siemens space coordinate transformation parameters is proposed. Finally, the S specimen recommended by ISO 10791-1-annex A was used for machining verification before and after thermal error compensation. By comparing the 0.129 mm deviation before compensation and the 0.085 mm deviation after compensation, the machining accuracy of parts is discovered to improve by 34.1%. Therefore, the above research lays a theoretical foundation for the follow-up thermal error detection and compensation for the asymmetric spindle of large torque CNC machine tools of the same type.