Modeling And Compensating For 3-Dimension Volumetric Errors Of CNC Machine Tools

The rapid development of the modern manufacturing technology requires enhancement of the precision machining and ultra-precision machining technology. Error compensation has become an important approach to improve the accuracy and performance of machine tools. So it is of great significance to study on compensating for the 3D volumetric errors of CNC machine tools. This work was supported by the National Natural Science Foundation of China (No. 50675199) and National S&T Major Project of China (No. 2009ZX04014-026). According to the research missions of the projects and current research situations, a method combined the theoretical research, computer simulation and experimental study was used to research modeling and compensating for the 3D volumetric errors of CNC machine tools. This dissertation has acquired the following main achievements:Using the multi-body system theory, analyzing of the topological structure, the lower body array of machine tools, the constraint condition and error transition matrix, the 3D volumetric errors of 3-axis machine tools was established.The laser step diagonal vector measurement was introduced, and the internal relation between vector measurement and error model of machine tools was revealed. Finally error separation technology was deduced, which can identify the linear displacement errors, straightness errors, angular errors and squareness errors.Open CNC System and position compensation function of PMAC were researched thoroughly, on this basis, a method of the volumetric errors compensation using 3D compensation table was proposed, and the mapping relation between work space of the machine tools and volumetric errors was established.Analytical software of the 3D volumetric errors for CNC machine tools based on MATLAB software was designed. Simulation experiment was done to verify the reliability and feasibility of the designed software platform.Finally, comparison experiment was conducted to verify the reliability of the error model and the feasibility of the measurement method. And then using the 3D compensation table, errors compensation experiment based on the Open CNC System was done, and the experimental results show that accuracy of CNC machine tool is improved significantly.