Maintainability Allocation Of Machining Center Based On Fault Correlation

CNC Machine tools is the foundation of equipment manufacturing,ensure its normal operation is an important task for our manufacturing enterprises.Reasonable maintainability design will endow CNC machine tool with good maintainability and high system efficiency,maintainability allocation is the core of maintainability design,the result of allocation directly affects the maintainability level of machine tools.However,the traditional maintainability allocation method neglects the fault correlation between subsystems,it is not suitable for complex systems such as CNC machine tools,so it is of great significance to explore the maintainability allocation method of NC machine tools based on fault correlation.On the basis of the reliability modeling methods at home and abroad,considering the multi-mode competition and the fault correlation among subsystems,this paper establishes the comprehensive failure rate model of subsystems,which lays the foundation for maintainability allocation.The subsystems of machining center is divided by functional structure mapping.Combined with fault and censored information,the average rank method is introduced to modify the rank of faults.Based on the reliability model of single failure mode,considering the competition between random failure and degenerate failure,this paper establishes a subsystem competitive failure reliability model.Taking the subsystem reliability model as edge distribution and introducing Gumbel Copula function,the joint reliability distribution model between subsystems is established,and genetic algorithm is used to solve the model parameters,the comprehensive failure rate model of subsystems based on fault correlation is established.By analyzing both the maintenance characteristics and influencing factors of machining center,the principle and index of machining center maintainability allocation are determined;Aiming at the problem that the traditional maintainability allocation method does not consider the weight of influence factors,and on the basis of the hypothesis that the subsystem is a series relation,this paper uses fuzzy mathematics to quantify the influencing factors and weights,and then establishes a maintenance fuzzy allocation model based on the comprehensive failure rate of the subsystem,and the maintainability allocation of the machining center is carried out by this method,and the analysis results show that the expected requirements can be met.The results can provide reference for the maintainability design of similar complex repairable systems.