Thick unevenness compensation in a hot rolling mill having automatic gage control

Hot rolling products with improved quality features such as thickness profile, strip width, flatness and material mechanical properties, are in increasing demand. The project goal is to improve the production quality in an existing hot rolling mill at Aceralia Steel Company, Aviles, Spain. This paper describes the design and implementation of a supervisory system for real-time compensation of uneven thickness on both sides of a rolled strip. The design is based on a multivariable process model, whose parameters are calculated online using measurement data from the mill. As a result, a computer system was developed that corrects the automatic gage control output from online acquired mill operation data. Previously, this task was done manually and periodically by a human operator. Manual correction is tedious and error prone, since it is based on visual inspection. Moreover, the proposed method leads to notorious improvement in the output strip quality, as the correcting signal may be continuously applied before the uneven thickness effect is visible.