Flatness adaptive control of a hot strip in finishing mills

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