A proposal improvement in flatness measurement in strip rolling

In strip rolling flatness of the final product is controlled inline with a roll sensor placed at the outgoing of the tandem mill to measure the longitudinal (in the rolling direction) internal stress profile throughout the coil. This profile involves resultant force and sometimes resultant moment (due to preset anomaly for example) equilibrated by the coiler. When strip is relaxed these two quantities are eliminated and there remain residual stresses in the strip. Since negative residual stresses are the main origin of defects, operators subtract the resultant force from measurements to visualize the residual stress profile in real time and detect negative values, without considering the resultant moment. In this paper we show that to predict flatness defects correctly we have to subtract resultant moment too. Otherwise, unpredictable defects manifest in the delivered product.