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

Hot rolling products are under an increasing demand of better quality features as thickness profile, strip width and flatness, and material mechanical properties. The project goal is the improvement of the production quality in an existing hot rolling mill at Aceralia Steel Corporation. In this paper the design and implementation of a supervisory system for the real-time compensation of uneven thickness on both sides of a rolled strip is described. The design is based on a multivariable process model, whose parameters are estimated on-line using measurement data from the mill. As a result, a computer system was developed that automatically corrects the automatic gauge control (AGC) output from on-line acquired mill operation data. Previously this task was made manually and periodically by a human operator. This manual correction is a tedious and error prone task, as it is based on visual inspection. Moreover, the proposed method leads to an improvement in the output strip quality, as the correction signal can be continuously applied before the uneven thickness effect is visible.