Reseach On Geometric Error Analysis And Precision Prediction Of VMC25100U Five-axis CNC Machine Tools Based On Test Specimen

Five-axis CNC machine tool is a kind of high-end CNC machine tools. It is specifically for complicated structure and the machining of free-form surface. With the more widely use of five-axis CNC machine tools in the field of precision machining, higher requirements are put forward for the machining accuracy and performance testing of five-axis CNC machine tools. Therefore, improving the accuracy and quality of CNC machine tool is one of the eternal goals of the advanced manufacturing science and technology. This dissertation aims at detection method of five-axis CNC machine tools based on test specimen. It covers the aspects of geometric error modeling, tracing and compensation. Details are as follows:1. On the analysis of the main error source of five-axis CNC machine tools, the concept of geometric error is clarified. The geometric error is very important for the accuracy of five-axis CNC machine tools. The elements of geometric error are introduced by dividing into sliding pair and revolute pair.2. According to the analysis of topological structure of the VMC25100 u five-axis CNC machine tool, the kinematic model is built based on multi-body system theory. On this basis, the geometric error model is proposed. The geometric error model can provide a foundation for the analysis and inspection of accuracy of machine tools.3. The prediction of machining accuracy of five-axis CNC machine tool is investigated by using error separation method. The contour errors of NAS979 specimen and “S” shaped specimen are analyzed. The result indicates the influence rule of the machining precision generated by the geometric errors of parts. According to the simulation results, it is easily to find out that each kinematic error has a different impact on the contour errors of the test specimen. The rotational errors affect the contour more severely comparing to the translational errors. Furthermore, the same work on the coupling between the geometric errors is investigated.4. The geometric error tracing technology of five-axis CNC machine tools is investigated. The error tracing method based on sensitivity analysis is proposed. A sensitivity model is built to analyze the precision of machine tool based on the direct matrix differential method. The sensitivity coefficient of each geometric error is calculated. The work provide a basis for the improvement of the machine tool design project and the precision deployment. A step-by-step compensation strategy is proposed aiming at the coupling characteristics of shiftable axis and rotary axis. On this basis, the geometric error compensation model is established and verified. The problem of error coupling is solved effectively.