A demand of quality improvement for flatness and edge-drop has been recently increasing in cold rolling of steel strip. The accurate control systems of strip shape and edge-drop have been developed for the new tandem cold rolling mill in Yawata Works, which has 5 stands of 6 Hi-UC·WR shift mill. The control system of strip shape consists of the initial set-up for roll benders, intermediate roll shifts of all stands, a feedback control for roll benders and roll levelling of No.5 stand by using signals of the shape meter which is installed at the exit of No.5 stand. The control system of edge-drop consists of the initial set-up for work roll shifts of No.14 stands and the feedforward control for work roll shifts of No.14 stands by using signals of the crown meter which is installed at the entry of No.1 stand. Application of these control systems to the new tandem cold mill shows the good controllability of flatness and edge-drop in cold rolling of steel strip. The strip flatness is within ±0.7% of inclination in an overall length of strip, and the accuracy of edge-drop is 1.2μm in average and within ±3μm in an overall length of strip.
