| 摘要 |
PURPOSE:To reduce the cost of production by forming a semi-finished product having inclined projecting parts and a web part made into a projecting by rolling from a rolling stock, then simultaneously subjecting the web part and flange parts to roll forming. CONSTITUTION:A billet is subjected to hot caliber rolling with plural hot rolling mills to form the semi-finished product 2. The flange parts 2 are inclined by >=15 deg. toward the outside and the projecting part is formed to the web part 4 in this stage. Such product 2 is subjected to stepwise cold working of the web 4 between an hourglass-shaped roller 13 and a drum-shaped roller 14 to form the approximately flat web part 4 and the square flange parts 4. The product is then simultaneously formed with horizontal rolls 16 and vertical rolls 17 as a final finish, by which a channel steel 20 is obtd. The need for a welding operation and leveling with press is eliminated by the above-mentioned method, by which the cost of production is reduced. |
