| 摘要 |
A method of forming a beam blank, wherein: said method comprises: a process in which a plate-shaped slab is reduction-rolled in the widthwise direction by means of working rolls having box calibers each formed at the center thereof with a belly, whereby side spreadings are generated at opposite end portions in the widthwise direction of said slab to provide a blank of being a dog-bone shape in cross-section; and a process in which said blank is rolled by means of working rolls having beam blank calibers to provide a beam blank being of a predetermined shape in cross section; said process, in which the plate-shaped slab is reduction-rolled in the widthwise direction by means of the working rolls having the box calibers each formed at the center thereof with the belly, preferably comprising: a first step in which said plate-shaped slab is reduction-rolled in the widthwise direction by means of box calibers each formed at the center thereof with a belly to provide grooves for positioning in the centers at opposite end faces in the widthwise direction of the plate-shaped slab; a second step in which said plate-shaped slab is further successively reduction-rolled in the widthwise direction by means of respective box calibers successively larger in caliber width than those used in the preceding step and each formed at the center thereof with a belly fit in said groove; and a third step in which said plate-shaped slab is further reduction-rolled in the widthwise direction by means of working rolls with flat bottoms or working rolls having box calibers each formed with a belly low in height, whereby recesses formed by use of said bellies at opposite end faces in the widthwise direction of the slab are lessened in depth and the side spreadings are further facilitated. |
