An Integrated MILP Model for Scheduling of Steelmaking-Continuous Casting With Cranes

Steelmaking-continuous casting (SCC) is the crucial step in steel production, and the process involves multiple production equipment (converters, refiners and continuous casting machine) and coordinated transport by multiple cranes. Scientific and reasonable scheduling of SCC with cranes can regulate the production rhythm and improve the efficiency of steel production. However, production equipment scheduling and crane scheduling are often solved separately in existing studies of SCC, which ignores the coupling relationship between them. Therefore, this paper proposes an integrated mixed integer linear programming (MILP) model for the SCC scheduling problem with cranes. Firstly, a MILP model with minimum residence time and completion time as objectives is established. Secondly, a disjunctive graph is established to describe the relationship between the processing tasks of the production equipment and the transport tasks of the crane. Thirdly, A new MILP model is proposed by simplifying the crane transport constraints based on the disjunctive graph. Finally, the validity and the superior computational performance of the new model are verified through 35 instances.