An Efficient and Effective Approach for the Scheduling of Steelmaking-continuous Casting Process With Multi Different Refining Routes

With the rapid development of market-oriented demand of iron and steel enterprises towards multi variety, small batch and on-time delivery, the functional requirements of steelmaking-continuous casting (SCC) production process with multi different refining routes for the dynamic balance of logistics, resources and time increase sharply. An effective scheduling of SCC process is important significance for improving the efficiency of steelmaking production and reducing the material and energy consumption. This paper develops an improved Lagrangian relaxation (LR) approach to address this problem based on time-indexed formulation while considering SCC scheduling performance indexes: sojourn time and tardiness of each job in the last stage. A direction controllable target estimation level adjustment strategy with tighter lower bound is addressed to overcome the premature convergence and weaken the oscillation in LR iteration. Computational experiment is verified based on the actual steelmaking plant in China. The computational results show that the approach improves the schedule strategy for the actual SCC process, and promotes the development of the schedule theory with the separate structure characteristics.