Mould temperature control in continuous casting for the reduction of surface defects

Temperature control in the continuous casting mould can have considerable implications for the eradication of surface defects that arise in the process. This paper presents auto regression with external inputs as a modelling tool to describe the effect of casting speed, mould level and water inlet temperatures on the temperature distribution in the mould. The accuracy of the modelling strategy is determined. The model can be used to design a closed-loop controller to maintain the mould temperature at a predefined value. The defects caused by temperature are therefore controlled implicitly through mould temperature, and the delay caused by measurement of defects is thus eliminated. Three controllers are designed and compared through simulation. It is found that an optimal regulator type controller delivers the best performance among the three controllers. Control of only one loop and a switching type controller show marginal improvements over the uncontrolled case.