REDUCING METHOD FOR CROP LOSS IN BLOOMING PROCESS

摘要

PURPOSE:To effectively reduce the crop loss, by forming a cave along each of thickness and breadth at a couple of opposite side planes of at least either one of top and bottom of an ingot, and then by applying a usual blooming process to the ingot. CONSTITUTION:The side planes 10A, 10B opposite across the thickness at the top and bottom of a blank material 6 to be bloomed are subjected to plural reversing rolling passes performed by horizontal rolls 18A, 18B; as a result, recesses 12A, 12B are formed. The length DELTAL of thus formed recess is made about 200-400mm.. Then, side planes 20A, 20B opposite across the breadth are subjected to plural rolling passes performed by vertical rolls 8A, 8B in order to form recesses 22A, 22B. In a thickness range wherein the shape of a side of the ingot 6 causes a double barreling as a result of a thickness reduction, the ratio of the breadth reduction to the thickness reduction is regulated to 0.40-0.65; in a thickness range wherein the shape of a side plane causes a single barreling, said ratio is adjusted to =0.3. By applying a blooming process to thus prepared ingot by forming said recesses, the crop loss resulting from an overlap and a fishtail is remarkably reduced.