Methods Research Of Dynamics Scheduling For The Re-entrant Mould Heat-treatment Flow-shop

Mould heat-treatment plays an important role in mould manufacturing process. Because of the long production cycle as well as the high energy consuming, mould heat-treatment has become the critical procedure that have a great influence on the overall production schedule. How to improve the production operation efficiency in heat treatment shop floor is a core issue to be solved in production schedule and control of mould enterprises. Thus, it is extremely significant to build up the production schedule and control system suited to the characteristics of mould heat-treatment, meanwhile, enhancing the delivery accuracy and lowering energy consuming of heat-treatment are quite meaningful.The jobs of heat-treatment belong to multiple incompatible job families and have re-entrant and batch processing characteristics. Their arrivals are dynamic and uncertain. Considering these characteristics stated above, heat-treatment shop floor scheduling is differentiated into certain re-entrant tempering and uncertain re-entrant tempering with time constraints. Based on the common features and divergences of these two types of scheduling, this paper is divided into the following four parts:(1) Fully considering the scheduling characteristics of heat-treatment shop floor as well as the enterprises’ actual requirements, this paper establishes a scheduling model on the basis of delivery accuracy and energy consumption. Through the two-level compromising programming model, the two-objective problem is transformed to one-objective one, besides, the weighted coefficients can make adjustments between the weights of delivery and energy-consuming performance. Considering the high requirements for dynamic arrival and scheduling efficiency of heat-treatment, this paper builds up a hybrid scheduling framework on the basis of event-driven mechanism and rolling schedule, making real-time response to quenching furnace as with job arrivals and rolling scheduling tempering tasks at the same time.(2) Taking certain re-entrant tempering as the research background, this paper constructs the scheduling mechanism for certain re-entrant tempering, then a dynamic batch scheduling algorithm is proposed based on proactive batching. Namely the two-level compromise programming model is established to determine the best quenching scenario and corresponding tempering scheduling for each job family, the global best decisions are then determined by an evaluation function. The simulation experiments are conducted to verify the effectiveness of the proposed approach and show that the results are promising as compared to the benchmark strategies.(3) Dynamic batch scheduling algorithm with time constraint and uncertain re-entrant tempering is proposed. Considering features like the time constraint and uncertain re-entrant tempering, this paper proposes the corresponding scheduling mechanism. A heuristic scheduling method is also proposed based on the previously proposed algorithm in certain re-entrant tempering schedule. The simulation experiments are conducted to verify the effectiveness of the proposed approach and show that the results are promising as compared to the benchmark strategies.(4) Environmental adaptability simulation experiments are conducted on the proposed dynamic batch scheduling algorithm, through arrival intensity, delivery intensity, heat-treatment cell bottleneck and job family quantity respectively. The corresponding scheduling environment and limitations for each algorithm is also researched.