Research On Maintenance Strategy Of Grouping Opportunistic Of Production Line And Condition-based Of Key Equipment Considering Failure Rate

Equipment is an important part of the production line,and maintenance is an important means to ensure the equipment normal operation.Choosing a reasonable maintenance method will affect the production efficiency,product quality and the economic benefits.At present,the production line maintenance strategy is mainly "preventive maintenance as the main,post maintenance as the supplement".The lack of analysis on the performance,characteristics and status of the equipment may lead to two major problems of "insufficient maintenance" and "excessive maintenance".Therefore,it is very important for enterprises to formulate effective maintenance strategies to improve reliability and economy.In this paper,the crankshaft production line is used as a research object to study the failure and maintenance operation rules,and to develop a more suitable maintenance strategy.The main contents of this paper are as follows:1.Propose the grey correlation interval Analytic hierarchy process(AHP)-Entropy method to divide the importance of production line equipment.First,a three-level importance evaluation index system is established considering the characteristics of operating rate,reliability,maintainability,economy and detectability.Next,the interval number is combined with the AHP and the Entropy method to obtain the interval AHP and the interval Entropy method,and the two methods are combined into an interval AHP-Entropy method to determine the combined weight of each evaluation index.Finally,conduct the grey correlation comprehensive evaluation and analysis,calculate and sort the grey correlation degree.The equipment is divided into the key equipment,important equipment,secondary equipment and general equipment.The grey correlation interval AHP,grey correlation interval Entropy method and the grey correlation interval AHP-Entropy method are compared.2.According to the collected data,the graphical method is used to judge the failure distribution model,and the Weibull distribution parameter is estimated by the least square method.In order to more accurately describe the equipment performance and the change of failure rate,a dynamic virtual age reduction factor related to cost,equipment age,maintenance times and maintenance learning effect,as well as a dynamic incremental failure rate factor related to the maintenance times are introduced to establish a mixed failure rate model.On the basis of the mixed failure rate model,the grouping maintenance models are established for the key equipment and secondary equipment,which take the reliability as the constraint,the maximum equipment availability and the minimum maintenance cost rate as the objective.For the important equipment,a multi-objective maintenance model with maintenance cost rate and availability as objectives is established.Using the MATLAB software to solve the problem,the optimal pre-maintenance times and each group interval are obtained.For the general equipment,the AHP-fuzzy comprehensive evaluation method is used to evaluate the effect of post maintenance.3.On the basis of the grouping maintenance,the opportunistic maintenance is introduced.Considering the economic and time correlation,taking the reliability as the constraint,the opportunistic pre-maintenance models are established with the objectives of minimizing the total maintenance cost and maximizing the availability.And the pre-maintenance activities are carried out for the equipment meeting the opportunistic maintenance conditions at the same time.Finally,use the MATLAB software to solve the model,formulate the best opportunistic maintenance plan for the production line,and compare it with the grouping maintenance plan.4.In order to maintain the healthy and efficient operation of the key equipment,the idea of condition-based maintenance is introduced.First,the Weibull proportional hazards model is applied to the condition-based maintenance decision modeling.The principal component analysis method is used to screen the covariates,which simplifies the equipment state parameters.The maximum likelihood estimation method and Newton iteration method are used to estimate model parameters.Secondly,taking the maximum equipment availability as the decision objective,a condition-based maintenance model is established.The model takes the maintenance decision control limit as the judgment condition.Once the status data of the equipment during operation exceeds the maintenance decision control limit,the appropriate maintenance mode can be selected.Finally,an example is performed to obtain the maintenance scope.