Study On The Intelligent Method Of Kinematic Error Compensation For NC Machine Tools

The purpose of adopting NC machining is to improve precision and efficiency , so the machining accuracy is one of the most important performance indexes for NC machine. Error compensation is a good way to improve accuracy of NC machining. But the process of NC machining is complicated, non-linear and uncertain. It almost can't be described precisely by mathematical model so that a well result of error compensation using traditional method cann't be got. Just for the purpose of enhancing error compensation accuracy of NC machine tools, this thesis was carried out.Based on the domestic and foreign research about error compensation, the ideal kinematic model and nonideal kinematic model for NC machine tools, the ideal gesture kinematic model and gesture error kinematic model for cutting tool were established by using the method of movement error analysis of multi-body system (MBS ).The above models were given for five-axes NC boring-milling machine DMU 70V (TPPPBRRW) manufactured by DMG. Correctly identifying of geometric error parameters is one of the most important preconditions for error compensation. The geometric error parameters were identified of translatory axes and rotary axes by using of MBS.To improve precision of error compensation, a model of error compensation based on Artificial Neural Networks (ANN) theory and identified with ANN through NC system was built with ANN, which possesses excellent approximation ability, generalization ability and self-learning ability. By combining dual-frequency laser interferometer used to measure displacement and straightness, three points method of measure rotary error in which are brought error calculation models based on MBS, identification of machine geometrical error and processing for measure parameters with Matlab software, the comprehensive training samples was gained, which further raised the network precision.The simulation demonstrates the correctness of volumetric kinematic error models for forming point and the feasibility of the ANN error compensation. Analyzing the result of the error compensation, conclusion that technology of ANN can be applied in controlling of NC machining error compensation can be gotten. Compared with traditional method of error compensation, the method of NC machining error compensation based on ANN possesses characteristics of high precision and good stability.