The effects of hot strip dimensions on the shape of cold rolled strip have been studied by process and laboratory measurements at the Rautaruuki Hameenlinna Works. Experimental data of strip crowns was gathered from 250 coils in hot, cold and temper rolled states. Transversal thickness profiles were measured with a laboratory thickness measurement device. Particular emphasis was put on the evolution of the edge drop during the cold rolling and temper rolling stages. The effects of hot strip crown on the shape of cold rolled strip were investigated by experimentally reducing the hot strip crown while keeping the mill settings constant in the cold strip mill. The reduction of the hot strip crown (measured 40 mm from the strip edge) by 20 mu m did present measurable changes in the edge drop or the strip. flatness. However, the relative crown remained at the average during cold rolling. The edge drop becomes more severe and begins further from the strip edge as the specific rolling fore. increases. The cutting of the hot strip edge makes the edge drop narrower and steeper.
展开▼
