Lot Splitting And Scheduling Problem In Job Shops Considering Assembly Relationship Between Parts

This paper is mainly intended to investigate lot streaming and scheduling problem in assembly job shop.Lot streaming scheduling problem,as an indispensable technique to improve production system,exists widely in all aspects of industrial production.Assembly job shop environment is more representative in actual production,and tends to have higher complexity than traditional JSP problems.Therefore,this research has both theoretical and practical significance.First of all,the assembly job shop lot streaming scheduling problem can be divided into two sub-problems: lot splitting optimization and sub-lot scheduling optimization.Based on system optimization,two sub-problems will be treated as a joint one for solution.The mathematical model for assembly job shop lot streaming scheduling is constructed,and three kinds of algorithms are put forward,which are based on the improved integrated-optimized algorithm,hierarchical-iterative-optimized-based hybrid algorithm and genetic algorithm respectively.Finally,comparative analysis of the proposed algorithms is carried out through the simulation experiment.Second,in order to meet the delivery reliability of customer demands,a complex lot streaming scheduling mathematical model is built,considering punishment for advanced delivery,delayed delivery tardiness and the delay of progress.Hybrid algorithm based on genetic algorithm and priority job dispatching rules is proposed,and through simulation experiment,the effectiveness and inherent characteristics of the proposed algorithm are verified in multiple dimensions,as priority dispatching rules,order scale and so on.Finally,most of the current studies on the assembly job shop lot streaming scheduling problem focus on the static environment.However,in the real production,the assembly job shop lot streaming scheduling problem has high uncertainty and complexity.Workload control is a production planning and control method specially designed for the workshop in ETO type enterprise and other highly complex production environment,which can effectively balance workload across the workshop and improve the order on-time delivery reliability.However,considering the gap between theory and reality,the adaptability of load control method in assembly job shop needs to be further evaluated and improved.Therefore,this paper mainly studies how to guarantee on-time delivery under an overall balanced workloads across workshops by shop scheduling in dynamic environment.A multi-layer hierarchical simulation model is established,and workload control is refined by proposing new order release methods integrated with priority dispatching rules.Simulation experiments are conducted to evaluate the influence of the combination of integrated approach on various performance indicators.