| 摘要 |
PURPOSE:To obtain a product excellent in shape dimensions by rolling a rough- shaped billet, having a recessing part of longitudinal direction at the outer-face center of its flange, by vertical rolls, having each a projecting part at the center of its outer periphery, so as to provide and acute angle to the front end of flange inner-face. CONSTITUTION:A rough shaped billet 10 is rolled by a break down mill to form a recessing part 12 without causing its deviation from the center of the outer face of a flange part 11. The projecting part 17 of a vertical roll 16 of the 1st stage in the next roughing universal mill, is fitted to the part 12. The face of projecting part 19 of a vertical roll 18 of the next stage is made to be parallel and stepped to its outside face 19a, and the part 12 is used as an introducing groove to bite the billet 10 between the rolls 18. Therefore, the width center of flange part 11 coincides accurately with the gap center between horizontal rolls 20. Further, an edger mill rolls the billet 10 so as to form an acute angle theta between the front-end face 21 and inner face 22 of flange. Accordingly, when the thick part 23 is correctingly rolled by an universal mill at the rear stage, the front-end shaped of flange is prevented from changing for the worse because the outer-face side of flange is remarkably extended. |
