The Joint Optimization Of Maintenance And Spare Inventory Policy For Rollers

Roller is an important tool for plastic deformation of rolling material and it is also the main consuming parts in Rolling Industry. The quality of roll not only directly influences the efficiency of the roller mill, but also the quality and yield of rolled products. The thesis studies joint optimization of the system composed of M independent rollers in the same production line. Combined with the characteristics of roller, analytical and simulation models were developed sequentially. The main contents of the thesis are as following:1) After analyzing the operating characteristics of rollers in the same production line, and classifying the roller in the same production line as a multi-unit system with many identical units, the thesis studies the maintenance, spare parts inventory strategy and the joint optimal decision of maintenance and spare parts inventory of the multi-unit system.2) Aiming at the roller system composed by multi-units of the same type, combining the maintenance characteristics of roller, and considering the perfect maintenance effect and assumptions of deterministic maintenance time, we establish the analytical model taking roll changing period, prevention gridding threshold and safety stock threshold S as the decision variable, and the minimum average cost rate in infinite time range as the target. In the process of solving the model, calculate the probability of scrape gridding demand and stock situation of roller with the method of continuous deterioration equipment's state space division. The genetic algorithm was used to solve the model.3) Considering the imperfect coping effect of the roller, establish the stimulation optimization model taking roll changing period, prevention gridding threshold and safety stock threshold S as the decision variable, and the minimum average cost rate in infinite time range as the target, and adopt the method combining discrete event simulation and genetic optimizing algorithm to solve the model.Experimental results these two models show that it is necessary to establishing the joint strategy. And the roll changing period and inventory parameters solved by the joint strategy is more reasonable, which can decrease the production cost of enterprises. The joint decision selects appropriate maintenance and inventory for enterprises, which provides excellent theoretical basis for the realization of to realize the reasonable resource allocation.