| 摘要 |
PURPOSE:To improve the yield of pipe making by providing sub-rolls between forming rolls and forge welding rolls and positioning the forge welding rolls and positioning the forge welding point in the inside diameter position of the forge welding rolls or before said position. CONSTITUTION:A skelp 2 heated in a heating furnace 1 is formed to a tubular body by forming rolls 3 and is then formed by sub-rolls 6 in succession thereto. A V angle theta is made half the angle in the prior art. Air is blown from an air nozzle 4a to a skelp edge 2' and oxygen is blown from an oxygen nozzle 4b to the forge weld point (a) and at the same time, said edge is forge-welded by forge welding rolls 5, 5'. The point (a) is positioned before the inside diameter (b) of the roll 5' by the above-mentioned method, by which oxygen is substantially supplied between (b)-(c) of the edge 2'. Since forge welding is accomplished simultaneously with oxygen blowing, the quality of the butt part and the yield of the product are improved. |
