Production Scheduling And Rescheduling For Discrete Stamping Job-shop

With the globalization of market and the diversification of customer demand,mass and continuous production mode is gradually replaced by discrete multi-varieties and small-batch production mode.In order to adapt to the ever-changing market demand,the highly flexible discrete production mode was adopted in automotive stamping job-shop,which makes the production process control particularly complicated.Thus,an efficient production scheduling optimization method was designed to guide production,it has become an important mean for enter:prises to reduce production costs,improve production efficiency and delivery satisfaction rate.This research is based on a Stamping Job-shop Scheduling Problem(SJSP)within an automobile manufacturing enter:prise.The related optimization theory and algorithm are used to study the production scheduling and rescheduling of discrete stamping job-shop.Aiming at the batch characteristic of discrete stamping production,an equal-sized batch production mode is proposed,which divides the whole batch into several smaller sub-batches and each sub-batch was scheduled as an independent individual.With the objectives of the makespan,the number of die changeovers and the processing cost,a discrete stamping production scheduling model based on equal-sized batch production mode was established.The non-dominated sorting genetic algorithm(NSGA-?)was designed to solve the model,and the effectiveness of the proposed method is verified by an instance.Analyzing the influence of the lot transfer ways between operations on the production cycle and die changeover,a production mode named buffer-stock production mode based on no-idle time transfer is presented and each sub-batch was transferred separately.According to the optimization objectives and constraints,a stamping production scheduling model based on buffer-stock production mode was established.Furthermore a genetic algorithm was designed to solve the model.Compared with full-sized batch production and equdal-sized batch production,the advantages of the proposed method in batch scheduling of stamping job-shop were verified.Aiming at the order inserting disturbance in the actual production process,the stamping production rescheduling model was established with the objective of minimizing the number of machine changes based on the stamping production scheduling model.The genetic algorithm was designed to solve the problem to ensure the optimal state of the scheduling scheme and the stable operation of the production system.Finally,the effectiveness of the rescheduling model and the algorithm was verified by an instance.Taking the production of stamping job-shops within a typical automobile enterprise as an example,a discrete stamping job-shop scheduling sy'stem based on multi-objective optimization was designed and developed.The proposed method was integrated into the system to realize the automation and intelligent scheduling of the stamping job-shop.The system mainly includes the following functional modules:system management,basic information management,planning and scheduling,task list and equipment maintenance/repair.The successful implementation and operation of the scheduling system in this enterprise verified the validity and feasibility of the proposed theory.