Research On Two-stage Collaborative Workshop Scheduling For Single Piece And Batch Coupling Casting Production

The foundry industry is the basic industry of Chinese manufacturing industry,which is indispensable in the development of the national economy.In China,casting production is mainly driven by the single-piece and small-batch production mode,which has the characteristics of various orders,complex production process and low automation of workshop.As a result,the resource allocation and scheduling in foundry are more complicated than those in the traditional job shop.To improve the production efficiency of manufacturing enterprises,it is significant to make full use of workshop resources and to make planning production schedules reasonably.In this regard,how to increase resource utilization rate,shorten production cycle and provide practical workshop scheduling strategies for foundry enterprises has become an urgent problem to be solved.Therefore,the foundry industry is took as the research object and the twostage collaborative scheduling strategy under multiple constraints is discussed in this research.The main research contents are as follows:(1)The characteristics of two-stage collaborative production in foundry are expounded based on the introduction of lost foam casting enterprise.Specifically,the multiple process constraints of casting production in the first stage are presented based on the practical production of foundry,while the flexible processing characteristics of castings in the second stage are analyzed accordingly.Besides,a two-stage collaborative scheduling strategy is designed for the two-stage production mechanism in foundry.(2)A weighted multi-objective optimization model with multiple process constraints includes alloy constraints and flask assembling constraints is constructed for the lot sizing and scheduling problem in the first stage,which aims at minimizing the vacancy rate of the flask and the maximum completion time in the first stage.With the consideration of the feature in first stage,i.e.batch first and scheduling later,a hybrid genetic NEH algorithm is designed to solve the proposed model.Moreover,computational results of simulation data obtained by the presented algorithm are compared with those achieved by other heuristic algorithms,which demonstrate the applicability of the proposed model and the superiority of the hybrid algorithm.(3)The coupling features of the first stage and the second stage are analyzed based on the single-piece scheduling problem in the second stage.Then,a flexible flow shop scheduling model considering the dynamic arrival time and the virtual operation is established,which has the goal of minimizing the maximal completion time of the second stage.To solve this model,an improved whale swarm algorithm with iterative counter is proposed,where the procedure of whale position movement is discretized and improved.Additionally,the effectiveness and superiority of the proposed algorithm are proved by comparing the computational results of simulation data with other algorithms.(4)The practical production data of a real-world foundry industry are given,which are modeled by the proposed mathematical model and solved by the presented algorithm.The obtained scheduling results indicate that the two-stage collaborative production scheduling strategy is effective and practical.