| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of a sheet bar for a hot rolled steel sheet, for reducing a yield loss, by reducing a width unsteady part of the sheet bar tip rear end.SOLUTION: A hot rolling process is composed of: a step of heating a slab; a step of drafting a width by a width press device; and a rough rolling step of having a plurality of rolling pass stages by using a horizontal rolling machine having a vertical type rolling machine on the inlet side, and manufactures the sheet bar for the hot rolled steel sheet. The manufacturing method of the sheet bar for the hot rolled steel sheet is provided for rolling the width by the vertical type rolling machine so that a prediction value &Dgr;Wand an N th width rolling amount &Dgr;Wsatisfy the following formula (1), by predicting a width spread amount &Dgr;Wby an N th horizontal rolling after finishing an (N-1) th pass, by respectively executing N th width rolling and horizontal rolling, on and after an N th pass, by executing only a first horizontal rolling in a first pass of the rough rolling, by forming the slab tip in a tongue shape in the width drafting step. &Dgr;W≤&Dgr;W(1), where N is an integer of 2 or more. |
