The Research On Thermal Error Compensation Of CNC Gear Hobbing Machine Tools

Thermal error becomes the largest error source and restricts the further improving of processing accuracy for gear hobbing machine. That’s because the machine tool design and manufacturing technology have become increasingly mature and perfect. Error compensation is effective and economical to reduce the hobbing thermal error in comparison with error avoiding. Therefore, in recent years, the research on thermal error compensation of CNC gear hobbing machine has gradually become hot at home, and many achievements have been obtained. However, the research for turret parts-the key components for gear hobbing thermal error on thermal characteristics simulation, thermal error modeling and compensation has not been found. According to Y3118CNC CNC gear hobbing machine, and selecting its head parts as the research object, the thorough discussion and research about the hobbing thermal-induced error dynamic compensation technology have been done.(1) The analysis of the thermal characteristics for the tool rest component of CNC gear hobbing machine tool was finished in theory, and then the basic work for the early period of thermal error compensation was completed. After clarifying the mechanical structure tool rest component, the tool rest component source of heat was analyzed basing on the theory of heat transfer, and the calculation method of the intensity of heat source and heat boundary conditions was illustrated. Finally, under the action of the source of heat, the tool rest component deformation influence on machining precision was expounded(2) The finite element method was used to do the simulation analysis of the temperature field and thermal error of the CNC gear hobbing machine tool parts with the technology of heat structural coupling. Through the simulation analysis,a better understanding of the turret parts thermal characteristics was gained,and the data source fot thermal error modeling was supplied. First, simplification of the tool parts was finished according to the realistic condition, the finite model was created and the analysis conditions like intensity were confirmed. Then, under the foundation of the previous work, The steady temperature field and deformation of the turret parts were simulated and the temperature field distribution and thermal deformation characteristics were explained. At last, the transient temperature field and deformation of the turret components were computed and the temperature rising feature and thermal error dynamic properties were analyzed. (3) The model of the CNC gear hobbing machine was obtained through thermal error modeling. The four thermal key points of the tool parts were identified with the clustering analysis method. The thermal error model of the X axis in the machine coordinate system was created applying with the multiple linear regression, and the model is accurate according to the data matching figure.(4) According to the CNC systems of FANUC and CIMS Institute, this paper offered three compensation strategies for different situations by comparing among different compensation methods.And the compensation strategies put up with by this paper can provide reference for the future study of compensation for thermal error.