Accuracy Prediction And Control Of Complex Surfaces For Multi-axis CNC Machining

With the rapid development of CNC machining technology, the complex surfaces are widely used in the aerospace,mold and die manufacturing field. The research of complex surfaces machining quality especially the process machining accuracy is becoming increasingly important. With regard to complex surfaces multi-axis machining, the machining accuracy is influenced by several factors such as cutting parameters, tool path and programming errors etc. Free-form curves and surfaces represented by parametric forms have become one of the most popular mathematic methods to describe the contour of machined components in CAD/CAM systems, and numerical control interpolation of curves and surfaces is an important factor influencing machining precision.In this thesis, by combining adaptive control theory with programming error control, an adaptive error compensation algorithms is proposed. Moreover, the tool-workpiece-machine coordinate system of DMU70V machining center is established and the tool axis angles are defined. The cutting edge models for solid ball end milling cutters are established, furthermore, the transformation matrix of ball end milling motion is derived. Besides, the algorithms of cutter location path generation in process of the whole machining system are obtained. Taking the machining of sinusoidal surfaces by a five-axis CNC machining center for example, the simulated tool paths and the cutter location points before and after adopting the adaptive compensation algorithms are gained.By utilizing the established adaptive error compensation algorithms, the ball end milling machined surface accuracy simulation algorithms are programmed using the engineering software MATLAB. Combined with the adaptive error compensation algorithms, cutting experiments are carried out, and the comparisons of test results and simulation accuracy show that the predicted results are in agreement with the measured values, which proves that the derived adaptive error compensation algorithms and the accuracy model are feasible and can predict and control precision effectively. It provides an effective approach for prediction and control of complex surface machining accuracy.