The Technical Study On The Tolerance Design Of The Parts Of The Five-axis NC Machine Tools Which Is Oriented To The Precision Of The Machine Processing

With the development of microelectronics and computer technology, the institutionalperformance of the CNC system has improved and the advanced control of CNC machiningprocess is increasing. The accuracy degree is growing more and more strict. However, withthe rapid development of the CNC machine tool, its manufacturing quality of the parts and theaccuracy requirements will be more stringent. Machining accuracy is an important indicatorused to measure the performance of CNC machining. Machining accuracy is constrained bymachine error. Error compensation has become a key issue of five-axis NC machiningaccuracy, measurement of the error and the technology of error modeling is the keytechnology of the error compensation, and they has become the focus of the research. Thisarticle refers to a large number of related literature，the model of geometric errors of five-axisCNC machine tools and the reverse calculating of machine parts precision parameters throughsynthesizing mathematical model using Genetic Algorithms were researched.In terms of machine tool geometric error modeling: By analyzing the causes of machineerrors, based on the theory of multi-body system, describing the institutions system topologyrelations for the RTTTR five-axis machine by a sequence of low-order body, calculating therelationship of the relative movement between each individual with the method ofhomogeneous characteristics matrix, and finally establish machine geometric error models.Through comprehensive mathematical model for reverse machine parts precisionaccuracy parameter: on the basis of the result of machine geometric error model and drawon the method of analogy size chain, getting the10-line method which is based on thegeometric error identification theory, put forward corresponding to displacement error toapproximate representation of the angular displacement and perpendicularity error, determinethe cost factor using the error correlation degree method. With the lowest tolerance andprocessing costs and meeting the machining accuracy as the goal, we may get acomprehensive precision mathematical model. According to the basic principle and operationprocess of genetic algorithm, using the toolkit graphical interface mode of MATLAB geneticalgorithm toolbox, parameters optimization for the established model and the final parametersof the optimal solution can be obtained. Finally, given the experimental verification concrete examples, based on the applicationsteps and methods of MATLAB genetic algorithm toolbox, substituting data, compared theoptimization data with the empirical value, so as to verify the feasibility of this process.