ROLLING METHOD FOR THICK PLATE

PURPOSE:To obtain rolled materials which are surely square in the final shape and have less unnecessary discarding parts by predicting the changes in shapes in all rolling stages, more particularly in the side edge parts in the width direction of the materials to be rolled and the crop parts at both ends in the longitudinal direction, and forming the shapes of the materials to be rolled prior to entering the respective rolling stages adequately in accordance with said prediction. CONSTITUTION:In order to prevent the drumlike shape in the broadside side edges of a material to be rolled by rolling, said material is rolled in such a way that the central part in its longitudinal direction is made thinner than both end parts by taking rolling reduction by the rate corresponding to the change in the predicted drumlike shape beforehand from a prescribed broadside rolling ratio. More specifically, the material to be rolled is meshed with the work rolls of the rolling mills which are set at the prescribed rolling reduction and where the preceding end side of said material is left by a suitable length, the work rolls are run reverse to provide a sectional difference at shown in figure (a). After said material is rotated by 90 deg. so as to be deviated in thickness in said end part, the deviated thickess part in said end part is concentrically rolled at a prescribed draft ratio whereby the rolled material of a plate T shape in figure (b) having a specified thickness is obtained. By said method both ends of the rolled material are subjected to staggered rolling on each side to form an I-shaped rolled material then the material is subjected to broadside rolling, whereby the I shape is annhilated by the offset effect of the drum-like shape.