Research On Compensation And Optimization Of Thermal Error On CNC Machine Tools

With the development of our country’s industry, the need of CNC(Computer Numerical Control)machine tools and it’s working precision are more and more high. It is especially impendence for high-grade CNC machine tools. High-grade CNC machine tools is even become the important indicator of measuring a country manufacturing sector level and overall national strength. Among sources of error in the machine, the thermal error is the biggest source of errors of CNC machine tools and precision processing machinery. Further more, the higher the precision machine tool, the greater the proportion of thermal error. For this reason, reducing the thermal error to improve the machining accuracy of precision machine tool has the vital significance. Comprehensive research contents of domestic and foreign researchers, the research of thermal error compensation technology centered on temperature sensitive point selection, thermal error modeling and the thermal deformation compensation.From the above three aspects, theories and methods are proposed, a lot of experiments and data processing are done, and take actual CNC machine tools for example to compensate the thermal error. The main contents of the paper are as follows:1) The methods of temperature-sensitive points selection of CNC machine tools have been researched, a comprehensive method based on fuzzy clustering analysis, gray correlation, regression analysis and determination coefficients is proposed to select temperature-sensitive points. Testing the practicability by lots of data.2) Pointing at the phenomenon that temperature-sensitive points will change under different season, make experiment in different season, to verify the changing of temperature-sensitive points. Moreover, proposed the method of subsection modeling.3) Processing two modeling method:MLR(multiple linear regression) and SVR (support vector regression). Demonstrating the compensate effect of this two model, and using subsection modeling to test the conclusion.4) Based on spindle speed map in national standards, propose different speed map. Making experiment under two situation:spindle speed according map and stay constant. Proposing the best experiment speed to build compensation model by processing experiment data.5) The thermal error compensation techniques specific use methods and experimental platform are described. Using principles and methods of DDB (Double Ball Bar) to compensate thermal error on another CNC machine tools.