Reliability Model And Its Application In Machine Tool Reliability Assessment

The manufacturing industry is an important part of the real economy of our country,and the CNC machine tool is the basic production and processing equipment in the manufacturing industry.The advanced degree of domestic CNC machine tools represents the development of the national industrial level.The problem of reliability has become the main reason for restricting the development of the machine tool field in China.Reliability engineering is very important in the whole life cycle of machine tools.Reasonable and accurate reliability modeling technology is very critical for the reliability research of CNC machine tools.The research object of this paper is CNC machine tool.Under the premise of taking reliability as the center,the paper explores cutting-edge technologies for reliability modeling and analysis of CNC machine tools,researches methods for establishing reliability models of CNC machine tools,parameter estimation methods for complex models,and test methods for models.Those explorations can provides a theoretical basis for the engineering applications of reliability.In this paper,the following achievements have been made in the reliability modeling and analysis of CNC machine tools.1)At first,the paper introduced the basic theory of system reliability analysis,and then summarizes the reliability engineering used in all kinds of simple model and derivation method and its application.The paper focuses on the analysis of the models commonly used in the reliability modeling of CNC machine tools and their parameter estimation methods and testing methods.2)Cutting tool is one of the most important components of machine tools.Its failure often occurs under the combined action of various failure causes,and different processing time failure data obey different distributions.In order to accurately evaluate the reliability of a tool,considering the influence of cutting parameters,the mixed model and the proportional hazards model are used to model the tool failure data.The Markov chain Monte Carlo method is used to solve the problem of model parameter estimation.With the proposed method,the tool reliability,mean life,tool life standard deviation,failure rate and mean residual life are obtained.An engineering example shows the applicability of the model.3)The fault data collection cycle of CNC machine tools is often very long.In this process,environmental changes and other factors often lead to the non homogeneity of the fault data.To solve the problem of reliability assessment for imperfect maintenance of multiple CNC machine tools with inhomogeneous fault data,a mixture power law-proportional intensity model based on Cox proportional hazards model is proposed.The general expression of the model is given,and the parameter estimation of the model is given by the method of nonlinear constraint programming to avoid the solution of the complex equations.The model was tested by combining the graph of total time on test and the analytical method.An example of engineering is analyzed,and the reliability indexes are given.It shows that the model is better than the single model and the minimal maintenance model,and the assessment result is more reasonable.