Research On Modeling And Compensation Of Integrated Error For Multi-axis CNC Machine

High-grade nc machine tools, especially precision multi-axis nc machine tools, is an important symbol to measure manufacturing levels of a country, it has extremely extensive application requirements in many manufacturing. Improving machine precision have two kinds of methods. One kind is Error Avoidance method, namely through improving CNC machine parts structure design, manufacture precision and assembling levels to eliminate Error sources as far as possible. Another kind is Error Compensation method, namely not changing the original machine structure and texture, through the Error sources analysis of machining process, modeling and compensation,change the actual activity to achieve ideal exercise trajectory, realized without the use of precision machining equipment precision machined. At present, through Error Avoidance method to improve the precision components manufacturing error of the machining accuracy of realization become more and more difficult to avoid methods, cost more and more is also high. Therefore, the development of CNC machine error compensation technology calls for stronger and stronger.This paper firstly based on multi-body system, with an four axis machining center for object, established an comprehensive mathematical model contains geometric error and error caused by thermal deformation, thoroughly analysed exchange work stations error on transmission of machining center and hot drift error influence on axes and other key problems, and solved the problem in the course of modeling. This error model provided a solid theoretical basis for precise compensation of machining center.Secondly, innovatively put forward positioning error modeling and forecasting method for CNC machine based on improved Least Squares Support Vector Machine (LS-SVM), performed XYZ triaxial positioning error measuring experiment by using laser interferometers, adopted compensation method of reverse clearance and single positioning error to compensate for position errors, put forward modeling method for positioning error based on weighted LS-SVM and the model parameters optimization method, and proved theoretically the accuracy and feasibility of the model.Finally, by the compensation experiments proved accuracy of error model based on weighted LS-SVM and feasibility of compensation method, and prediction and compensation by this method for CNC each axis, can effectively enhanced the CNC machining accuracy.This paper also innovatively proposed modeling compensating method by LS-SVM facing error real-time compensation technology, researched and put forward realization process of real-time error compensation program and compensating control system.