Economic Research On DSVSST~2 Control Chart Considering Condition-based Maintenance Strateg

Statistical process control and equipment maintenance decision-making are two major methods to ensure the stability of the production system and improve product quality.The former ensures the stability of the production process by monitoring the core quality indicators of the product to prevent the product from deviating from the expected quality;the latter formulates the best maintenance plan based on the operation of the equipment and historical data of failures to prevent equipment failures from causing production stagnation to ensure the reliability of the production process.For the production process of products with multiple quality characteristics,dynamic control charts can detect small quality deviations in time and find process abnormalities in time.In addition,combining the dynamic control chart with the condition-based maintenance strategy to construct a joint optimization model of the dynamic multivariate control chart and the condition-based maintenance can provide sufficient guarantee for the stability and reliability of the production system.Therefore,the research on the optimal design of dynamic multivariate control chart and its combination with maintenance strategy has great theoretical significance and practical application value.The main research contents of this paper are as follows:First,for the multivariate normal population mean vector shift problem,a double sampling variable sample size control chart is constructed by combining the double sampling strategy,the variable sample size strategy and theT~2 control chart.According to the actual operation state of the process,a Markov chain transition probability matrix is constructed,and the statistical performance index of the control chart is calculated.Considering the operation cost,false alarm loss,sampling cost and maintenance cost under the normal and abnormal state of the process,combined with the Lorenzen-Vance economic model,an economic model of DVSSST~2 control chart is proposed.The control chart parameters and expected cost per unit time are solved by genetic algorithm.Finally,the influence of the cost parameters of the model on the control chart parameters is analyzed.Secondly,the double-sampling variable sample size T~2 control chart is integrated with production equipment maintenance,and a joint model of dynamic multivariate control chart and condition-based maintenance decision-making under mixed failure mechanism is proposed.Analyze the internal relationship between the process state and equipment failure,divide the production process into five situations,adopt the conditional maintenance strategy including preventive maintenance,predictive maintenance and corrective maintenance,construct the economic model of the combination of DVSSST~2 control chart and conditional maintenance,Under the premise of the minimum expected cost per unit time,a method for determining preventive maintenance nodes and control chart parameters is proposed.The influence of model parameters on the joint optimal design of control charts and preventive maintenance is studied.