Research On Reliability Test And Evaluation Technology Of Chain Tool Magazine And Automatic Tool Changer

The tool magazine and automatic tool changer are one of the key functional components of CNC machine tools or large machining centers,which reliability directly affects the reliability of machine tools,so it is of great significance for reliability research.Combined with the"Critical Machine Tool Reliability Improvement Project"project,the paper studies performance detection technology,fault analysis,reliability test methods,reliability evaluation and other issues for the chain tool magazine and automatic tool changer to provide theoretical basis and improvement plan for reliability growth.By studying the chain tool magazine and automatic tool changer performance detection technology for reliability test,it provides effective support for state detection in reliability test.Aiming at the detection technology of dynamic precision,a quantitative detection method of chain tool magazine dynamic precision based on laser displacement sensor and standard tool holder compensation and a qualitative detection method for dynamic accuracy of automatic tool changer are proposed.A vibration acceleration acquisition system based on Doppler laser vibrometer,acceleration sensor and data acquisition system was developed for vibration acceleration detection technology.Based on the comprehensive performance detection technology,the drive motor current,temperature,noise and pressure detection system was built by different sensors.According to the proposed performance detection technology,the relationship between the performance tolerance and the fault of the chain tool magazine and the automatic tool changer is studied.With The relationship between tolerance and fault is analyzed through the performance test,which are the dynamic accuracy,the vibration acceleration and the comprehensive performance.The specific tolerance range of the chain tool magazine motion accuracy,automatic tool changer vibration acceleration,noise and pressure is determined.Through the observation of the fault interval and fault of the chain tool magazine and the automatic tool changer,the reliability test is studied.the early fault reliability test and the constant or step stress accelerated life test method are proposed.The tool change numbers between failures is obtained by constant stress accelerated life fixed-end censoring test.Then the test data is amplified by virtual augmentation theory to establish Weibull distribution model.Next,the parameters of Weibull distribution model are estimated with nonlinear least squares method.Finally,Weibull distribution model is verified by linear correlation test and K-S test.Through the chain tool magazine and automatic tool changer performance test and reliability test,the corresponding reliability evaluation technology is proposed.the mean tool change numbers between failures（MTCNBF）and mean time between failures（MTBF）values are separately calculated by reliability test and virtual augmentation theory.The mean time to Repair（MTTR）and inherent reliability（A_i）is also theoretically analyzed.Based on the reliability evaluation technology of Weibull distribution,the value of reliable life（t_R）,reliability（R（t））and failure rate（λ（t））are determined by the virtual augmentation theory.Then,the one-side confidence of t_R and R（t）are theoretically analyzed.The former ist?_R,L,the latter is R_L（t）.Finally,the reliability growth measures of electrical systems and mechanical systems are proposed for the weak link of reliability.