Abstract: A method of controlling the rolling efficiency in a continuous hot rolling process. A rolling schedule and a conveying schedule are determined on a mill line for the slabs arranged in succession based on an aimed extraction temperature of the slabs from a heating furnace and a predetermined temperature at the exit of a finish mill. A minimum extraction pitch is calculated for the slabs from the heating furnace under restriction of the side of the mill line, and a different minimum extraction pitch is calculated for slabs from the heating furnace under restriction of the side of the heating furnace based on slab temperature charged to the heating furnace and the aimed extraction temperature. An optimum extraction pitch is determined for slabs from the heating furnace by comparing both of the minimum extraction pitches. With such a method, the continuous hot rolling operation is carried out under an optimum condition.

Abstract: A method of controlling the rolling efficiency in a continuous hot rolling process including the steps of inputting a total weight of and the time intervals of slabs already extracted from a heating furnace in a period from the present time up to any previous time, a total weight and a forecast furnace residence time of slabs charged in the heating furnace and a total weight of any number of slabs to be charged, and calculating the desired rolling efficiency of the slabs to be charged to thereby control the overall average rolling efficiency to a predetermined value. With such a method, the total weight of the slabs to be rolled in a unit time is maintained to a predetermined value.

Abstract: A control method comprises predetermining a or presuming a fuel flow rate for each of three control zones of a continuous slab reheating furnace, predicting each slab temperature after a plurality of time intervals from the presumed fuel flow rate, and controlling the fuel flow rate for each zone so as to minimize the sum of the differences between the predicted temperatures and corresponding objective temperature rise curves for all the slabs. Alternatively, the method may comprise sensing flow rates of the fuel and air for each zone at time intervals .DELTA.t, calculating the temperature profile within the furnace and then the temperature of each slab at the present time point from the sensed flow rates, repeating the calculations with the calculated slab temperature and any presumed fuel flow rate for each zone to predict the temperature profile within the furnace and each slab temperature after .DELTA.