Methods And System Of Roll Pass Optimization In Hot Rolling Process Of Wire Rods And Bars

Order planning scheduling is an important decision problem for intelligent manufacturing in the iron and steel enterprises.It's a complex combinatorial optimization problem that the production planning of each production line need to be worked out considering processing technology,order information,stock information,logistics status and so on.As a critical process of steel production,hot rolling plays a part in linking between the preceding and the following process.There is a large optimized space in its large-scale continuous production process with high frequency.Drawing up an efficient rolling planning for each rolling unit plays an essential optimized role in overall order planning.This thesis mainly discusses a roll pass optimization problem in hot rolling process of wire rods and bars,which decides rolling sequence of rolling units to optimize switch sequence between roll passes,reduce switch cost and improve the continuity of rolling production.Roll pass optimization problem is analogous to TSP(Travelling Salesman Problem)in research area of combinatorial optimization.It can be divided into two categories according to the actual application scenarios:one without time window constraints is suitable for the stock material scheduling and the other engaged time window constraints is suitable for the material scheduling of continuous rolling production.Mixed integer programming models are formulated in this thesis based on different characteristics of the two roll pass optimization problems.To improve the efficiency of the models,the corresponding model optimization strategies are designed according to the characteristics of each model.Benders Decomposition algorithm is used to solve two roll pass optimization problem.The test results using the actual data of iron and steel enterprises show that Benders Decomposition algorithm can effectively solve the problem of roll pass optimization problem without time window constraints,but the solving ability of the problem with time window constraints is not satisfactory.For this reason,the heuristic Rollout algorithm and its improved algorithm are also proposed,which can effectively solve large-scale roll pass optimization problem with time window constraints.Finally,in order to apply the theoretical research to the actual rolling planning scheduling process in iron and steel enterprises,this thesis designs and develops the Roll Pass Optimization System implanted Benders Decomposition algorithm of roll pass optimization problem without time window constraints and Rollout algorithm of roll pass optimization problem with time window constraints.