Research On Reliability Modeling And Prediction Technology Of Turning Center

Since the reform and opening up, China have made breakthroughs in the field of CNC machine tools, both in the high-speed, high-precision, and composition, etc. However, compared with developed countries, they still lack the core competitiveness. There are some big gaps in terms of reliability and accuracy preservation, etc. particularly in terms of reliability. CNC machine tools, especially the high-end CNC machine tools, are complex, expensive, and mostly small batch production. Thus, it is difficult to obtain their reliability index by statistical sampling experiments. The real reliability index of the product can be exactly known only by recording and analyzing its fault information accurately in the process of use from implementation to retirement. However, this method is not much valuable. Therefore, how to predict the reliability of the product in design part is essential.In this paper, with the support of the national "high-grade CNC machine tools and basic manufacturing equipment" major science and technology projects--research and application of manufacturing technology and key assembly of electronic controlled common rail diesel engine injection system, the reliability modeling and prediction techniques of the injector cylinder body forming and thread rolling processing high-precision complex CNC turning center in the development process are studied. The main contents are as follows:(1) Based on the reliability modeling and prediction theory, the characteristics of the reliability prediction of turning center are analyzed, and the hierarchical division of the reliability prediction work-oriented turning center is completed.(2) The fault data of similar objects of the turning center subsystem are collected and processed, and the reliability indexes are calculated. The fault data are preliminarily analyzed and the distribution models are primarily selected; the undetermined parameters of the primary model are estimated by using linear regression method, and the linear correlation and the goodness of fit are tested by combining graphic method and K-S test method; the reliability model of similar objects of each subsystem are determined, and function curve is drawn by MATLAB.(3) Aiming at the turning center subsystem, the reliability fuzzy prediction method based on similar product method and Vague set(VSA) is proposed. The subsystem reliability prediction model based on the similar product method and the reliability comprehensive evaluation model based on Vague set is established. Based on the experience of experts, the comprehensive evaluation of reliability level of the turning center subsystems and their similar objects are obtained respectively, and the reliability correction factor of the turning center subsystem based on their similar objects are solved. Finally, estimated value of reliability index of each subsystem are predicted, and the fault data distribution model are obtained.(4) Define the system definition, and the reliability block diagram model between the whole turning center and its subsystem is constructed. Based on this model, the whole turning center reliability prediction mathematical model has been established, and the reliability of the machining center machine is estimated by the mathematical analytic method. The basic principle of Monte Carlo simulation method, the algorithm logic and the basic process of realizing the whole turning center reliability Monte Carlo simulation and prediction are studied. Programming in the environment of MATLAB, and the simulation results and the expected result is predicted by the mathematical analysis method are analyzed.