Flatness control of strip in continuous hot rolling processes

In order to improve the flatness of hot rolled strip in hot strip finishing mills, a novel segmented looper system is developed, which called the Flatness Sensing Inter-stand Looper (FlatSIL) system. The FlatSIL system measures the tension along the direction of the strip width by using segmented rolls, and the tension profile is calculated. Using the tension profile, the flatness control system of hot strip can be constructed. The new flatness control system works for the full strip length during strip rolling as far as the tension profile-measuring device and the work roll bender are on. To control the flatness of hot strip, self-tuning algorithm using the recursive least mean square method is applied to update PI gains. By the computer simulation and experiment, the performance of flatness control systems with the fixed and self-tuning PI gains is compared.