Constraint Programming Based Model and Algorithm for Solving Steelmaking and Continuous Casting Scheduling Problem with Adjustable Casting Time

The Steelmaking-Continuous Casting (SCC) scheduling problem is usually regarded as a type of hybrid flow-shop scheduling problems (HFSP) with special process constraints. To research the SCC scheduling problem, a Constraint Programming (CP) model is established with the objective of minimizing the makespan and the total waiting time between stages of charges. Based on the actual production data from one steel plant in China, a dataset is generated and a CP Optimizer is used to solve the model. According to two indicators of makespan and total waiting time, the comparison experiments between CP model and manual scheduling are carried out on instances with different problem sizes under a variety of working conditions and scenarios. The experimental results show that the solution found by CP model is significantly better than manual scheduling, which verifies the effectiveness of CP model on SCC scheduling problem.