Hot strip width control method by using looper tension measuring system in finishing mill

A high precision hot strip width control method has been developed in this study by applying an interstand looper tension measuring system at the finishing mill stands. As the width deviation of hot rolled steel strip is closely related to abnormal increase in the interstrip tension, an on-line measuring device of looper tension and a data analyzing system were developed in this study. To determine dominant factors that will cause local width shortage, the logged data sets of bar width, bar thickness, looper tension, and strip thickness along the strip length were correlated with the data set of strip width change. With the result of the correlation analysis, existing sequence control logic and parameters for looper actuator were modified for strip width quality and the gains of the looper control were refined for stable operation during the full passage of rolled strip. The on-line tension measurement and tension feedback control for the looper system, improved the strip travelling stability and reduced strip width deviation in the strip top end region.