| 摘要 |
PURPOSE:To manufacture square steel pipe continuously at low cost by suspending transportation of product made by bending a steel plate of fixed length to the shape that approximates to a square steel pipe, and after tack welding the formed product, making it into regular shape of square steel pipe, high frequency welding the butted ends and cutting off the tack welded part utilizing the time of suspension. CONSTITUTION:After forming 1 of a steel plate A of fixed length into the shape that approximates to a square steel pipe, the formed product B is put successively on a transportation passage 12 and carried. Transportation is suspended temporarily, and upper side and lower side of the product B are tack welded by a tack welding machine 2 to obtain a continuous formed product B. The product B is sent to a forming roll 3 and pressed from inside and outside in cooperation with a core roll 4, and formed into regular shape. Then, the left and right butted ends are high frequency welded 5 during the time of suspension. The product B is cooled 7 and leveled 8, and tack welded part is separated 10 utilizing the time of suspension, and a square steel pipe C having specified dimension is manufactured continuously. Since tack welding, high frequency welding and separation are performed during the time of temporary suspension of transportation, moving of each equipment is not necessary and the equipment cost can be reduced. |
