METHOD FOR CONTROLLING SHAPE OF THIN PLATE

PURPOSE:To control a shape of a thin plate with the aid of a coolant having an excellent responsiveness, by obtaining a predictive shape basing on a detected shape at the exit and a required mechanically operating quantity, and controlling the flow rate of a nozzle by making it correspond to a reference value, in a cold rolling of a thin plate. CONSTITUTION:A shape in the width direction of a thin plate is detected at the exit of the rolls of a mill to obtain the difference of it from a desired shape. A predictive shape after changing a mechanically operating quantity is calculated to obtain an optimum mechanically operating quantity so as to minimize the maximum value of its absolute value. A reference value epsilonB against a predictive shape deltaepsilon(X)P at that time is set to calculate a point of intersection of the two, and the regions 1-3 in which the predictive shape deltaepsilon(X)P is larger than the reference value epsilonB between respective intersecting points are obtained in sequence from one end of the plate and in sequence from the end space between intersecting points of respective spaces to obtain the position where the difference deltaepsilon'(X)P between the two is maximum. Thus the flow rate is controlled by making a flow rate of nozzle corresponding to this position maximum and multiplying a flow rate of nozzle lower than it by a factor of