The controlled cooling of hot rolled strip: a combination of physical modeling, control problems and practical adaption

The control of the temperature and the cooling patterns of a hot strip mill, in which hot rolled steel is cooled with water directly after the finishing mill and before the material is coiled, is discussed. The control of the temperature and the cooling patterns are important because of the physical transitions in the steel. For this control, linearized models are used in an online computer. These models are deduced from theoretical models and adapted to practice. The parameter estimation for some of these models is done offline, other parameters can be estimated online. Since it is possible to deduce several different physical models for the waterjet cooling it is not feasible to design an accurate online water cooling model. Therefore, a combination of models was designed and run parallel to the process. Using statistical analysis the best fitting form is chosen