Constraint Satisfaction-based Optimization Methods For Slab-design And Slab-match Of Medium Plate

Under the tendency of economic globalization and market segmentation,customer requirement turns to be more diverse and personalized,the order structure of the steel enterprises is gradually changed to multi-variety and small-batch.This change brings new challenges to the steel industry which implements the large-scale manufacturing mode.Compared with other steel products,the slab-design and slab-match problem of medium plates is more difficult due to its diversification of specifications,complex rolling process,strong production constraints.To overcome the above difficulties,this thesis researches the slab-design and slab-match optimization problem combined characteristics of the medium plate production process and constraint satisfaction method.To model the slab-design and slab-match optimization problem of medium plate,constraint satisfaction technology is used.Firstly,the characteristics of the slab-design and production process of medium plate are described in detail.Furthermore,the constraints and objective functions to be considered in the slab-design optimization of medium plate are summarized.Finally,a modeling method based on constrained satisfaction technology is studied for slab-design problem of medium plate.To solve slab-design optimization problem of medium plate with the constant length and width,the constraint satisfaction method integrated with the heuristic rules is designed.Considering the constraints of plate specifications and the constraints of the heating furnace,a optimization model based on constrained satisfaction for slab-design problem with the objective of minimizing surplus material is established.Solution of the model is divided into two stages: mother plate design and slab design.First,by sorting the plate of customer order initialization,heuristic strategies including maximum variable-first,easy loading-first and symmetry breaking are applied.this thesis constructs an optimization algorithm based on constrained satisfaction technology for slab-design problem of medium plate,combination design of mother plate is finished.Then,mother plate specification is converted to slab specification by the constraint constant volume-based,to achieve slab design.The experimental results show that the proposed model and algorithm have good performance in reducing the surplus material and improving the efficiency of the computing compared with the manual design method.To solve slab-match optimization problem of the medium plate with constant width and nonconstant length,the constraint satisfaction method integrated with the process knowledge is designed.Considering the flexible constraints of indefinite length for plate,attribute constraints of plate,specifications constraints of slab and other conditions,a slab-match optimization model based on constrained satisfaction for inventory with the objective of maximizing the utilization of slab is established.The model solution is divided into two stages: slab specification conversion and mother plate matching optimization.First,inventory slab specification is converted to mother plate specification by the constraint constant volume-based,get the length of mother plate.Second,by sorting the plate of order initialization,heuristic strategies based on process knowledge is presented,including selection strategy of plate variable set based on maximum delivery priority,fixed length strategy of maximum inventory application-based,Selection of plate attributes based on minimization of cutting conversions.On this basis,an optimization algorithm based on constrained satisfaction technology for slab-match optimization problem of medium plate is presented.mother plate matching optimization is realized.The experimental results show that the proposed model and algorithm have good effect in improving the utilization of inventory slab,production efficiency and shortening the time of solving the problem.