| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method for a rough shape billet for a large-sized wide-flange shape by which the large-sized wide flange shape having the inside measurement of the web of >= about 600 mm and the leg length of >= about 200 mm can be manufactured by rolling with existing equipment. SOLUTION: A billet is made into an intermediate rough shape billet having a dog-bone-shaped cross-sectional shape by a first rough rolling and the second rough rolling is applied to the intermediate rough shape billet. By using grooved rolls 2, 2A having a first box-shaped caliber 3 having a flat part 20 and protrusive part 21 on the bottom, second box-shaped caliber 4 having only a flat part or a flat part and inclined parts on the bottom and forming caliber 5, the second rough rolling includes a 1st stage where the width is enlarged while forming recesses by reducing the approximately center part in the width direction of the flanges 10 with the protrusive parts of first box-shaped calibers, second stage where the width is increased by reducing the flanges with the recess by the second box-shaped caliber, third stage where the web is reduced and the leg lengths of the flanges by releasing the end parts of the flanges and 4th stage where the thicknesses in the end parts of the flanges are increased by reducing the flanges in the width direction by the flat part of the first and second box-shaped calibers.
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