Research On Evaluation, Allocation And Prediction Of Reliability For High-speed Precision CNC Lathes

CNC machine tools were the foundations of manufacturing industry; their reliability level directly affected the development of China’s manufacturing industry, reliability as an important indicator measure of the quality level of high-grade CNC, reliability evaluation, allocation and prediction had become the focus of attention of the state and enterprises. According to the national science and technology major projects "high-grade CNC machine tools and basic manufacturing equipment" —ADGM series high-speed precision CNC lathes and turning centers(2012ZX04005-012), in certain domestic high-speed precision CNC lathes as the research object, paper researched its reliability evaluation, allocation and prediction.The main contents of this paper include the following:1 Completed reliability evaluation of CNC lathes based on mixed Weibull distribution. Through analyzed and processed the collected 51 failure data, determined its conform to Weibull distribution model, single and mixed Weibull distribution model of failure data was respectively set up, and used the D-test test the goodness of the model,compared with the results, determined the mixed Weibull distribution model was conformed to the actual situation, then used nonlinear least squares estimated parameters of mixed Weibull mode, Finally calculated the reliability indicators of CNC lathes based on determined distribution model.2 Completed reliability allocation of CNC lathes based on improved fuzzy analytic hierarchy process. Because of complexity of high-speed precision CNC lathes, many influencing factors of reliability allocation weren’t accurate measurement, To simplify high-speed precision CNC lathes into 12 subsystems, reliability level distribution model was established comprehensive consideration of CNC lathes system and 6 kinds of factors influencing reliability allocation, reliability allocation was carried out by using improved FAHP, Finally by compared verification shows that, improved FAHP was usability to reliability distribution of high-speed precision CNC lathes.3 Completed reliability prediction of critical subsystems based on gray theory. With the help of the existing fault information and according to the characteristics of failure data, GM(1, 1) forecasting model of electrical system was established on the basis of grey theory. Processed the collected of Time between failures and verified their smoothness, quasi-index characteristics, GM(1,1) forecasting model was established under the premise of certain condition, residual test, correlation test and posterior error test were tested to the forecasting model, Finally proposed three different solutions and established their forecasting model respectively, compared three kinds of prediction model and determined the optimal solution, completed reliability prediction of electrical system, and developed reliability prediction software based on gray theory.Researched results of this paper had been applied in the reliability design of ADGM series high-speed precision CNC lathes.