| 摘要 |
PURPOSE:To form a channel steel having no surface flaw by rolling a pair of flange parts and a web part so that those thicknesses are equal to those of a product, then connecting parts between the flange and web parts are bent by an about right angle, further, forming parallel flange parts and a flat web part. CONSTITUTION:A billet is heated and sequentially rolled by rolling rolls to obtain a half-formed product 2 in which thicknesses of flange parts 3 and a web part 4 are equal to those of a product, a pair of the flange parts 3 and the web part 4 are in a straight lined shape, a right angled projecting part 6 is formed at corners 5 at which the flange parts 3 and the web part 4 are connected, and a recessed part 7 whose curvature radius is 2 or more times a thickness of the flange parts 3 is formed on the backside of the projecting part 6. Then, the half-formed product 2 is bitten by a recessed roller 13 and a projecting roller 14 to bend the flange parts 3 by an angle near to a right angle to the web part 4. Succeedingly, a pair of horizontal rolls 16 and a pair of vertical rolls 17 form a channel steel 20 having a pair of the flange parts 3 and the flat web part 4. |
