Research On Batch Scheduling Of Hot-rolled Steel Tubes With Machine Constraints

The core machine in the production of seamless steel pipe hot-rolled is the hot-rolled mill,the main constraints of hot-rolled batch scheduling come from the machine availability and process requirements of the hot-rolled mill.Therefore,in scheduling method of the seamless steel pipe hot-rolled,full consideration must be given to machine related constraints such as machine adjustment,machine maintenance,machine breakdown,and machine eligibility constraint.For several types of typical machine constraints in the production of seamless steel pipe hot-rolled,this paper analyzes the characteristics of the hot-rolled batch scheduling problem,discusses the corresponding optimization properties in combination with specific goals,establishes problem models and develops solution algorithms.The main research contents and innovations are as follows:(1)In view of the process characteristics of machine adjustment in the production of seamless steel pipe hot-rolled,the relationship between the specification-based sequence-dependent of machine adjustment and meeting the delivery requirements is analyzed.Based on these properties,the optimization rules for adjustment time and delivery time are proposed.With the optimization goal of minimizing the total equipment adjustment time and the total tardiness,a fast reordering neighborhood search multi-objective algorithm is designed based on the evolutionary algorithm framework.The experimental results of actual production data show that embedding optimization rules based on the characteristics of the problem in the framework of evolutionary algorithms can provide decision makers with effective non-dominated solution scheduling schemes.(2)On the basis of the above research,for the hot-rolled batch scheduling problem considering delivery requirements and machine adjustment characteristics in a fixed machine maintenance environment,the goal of minimizing machine adjustment time,minimizing machine idle time and minimizing tardiness is established.And a two-stage heuristic algorithm for local reordering based on optimization strategy is designed.In the first stage of the algorithm,the earliest delivery date priority rule is used to obtain the initial hot-rolled batch set with minimum tardiness;in the second stage,three optimization operations are designed:combined batch pre-interpolation,partial reordering and partial optimization.And the effectiveness of the algorithm is verified through actual production data experiments.(3)For machine breakdown in a dynamic environment,the problem of hot-rolled batch re-scheduling considering machine breakdown is studied.From the perspective of re-matching the pass system of rollers after breakdown to maintain continuous production,an off-line repair and parallel production strategy is proposed,and a multi-objective mathematical model is established to minimize the total completion time and minimize the tardiness.Through the analysis of the influence range of the pass damage when the roller breakdown,a two-stage re-scheduling heuristic algorithm is designed.In the first stage of the algorithm,a hole-pattern and specifications matching algorithm based on reverse searching is designed to generate the initial solution for scheduling based on the breakdown location.In the second stage,based on the characteristics of the problem,a fast neighborhood search strategy is designed to optimize the initial solution.Finally,simulation experiments show that the algorithm achieves the purpose of maintaining production stability and reducing production costs through effective use of breakdown repair time and re-scheduling of the original solution.(4)For two parallel hot-rolled mills environment with different machine processing specifications,the hot-rolled batch parallel machine scheduling problem considering machine eligibility constraint is studied.With the goal of minimizing machine adjustment time and minimizing the maximum completion time,a multi-objective mathematical model was established.By analyzing the processing capabilities of the two hot-rolled mills,it is transformed into a batch sequencing problem on a single machine and a batch assignment problem on multiple machines,and a two-stage heuristic algorithm based on the sequencing and assignment rules is designed.In the first stage,the batch sorting on a single machine is completed in combination with an optimal adjustment time rules,and at the same time,the machine is assigned to the intersection of the hot-rolled mill by using the earliest completion time rule.In the second stage,four optimization rules is designed based on the eligibility restriction characteristics of the two rolling mills to optimize the initial scheduling plan and improve machine efficiency.Simulation experiments show that this algorithm is effective in solving such parallel machine scheduling problems with machine eligibility constraint.