| 摘要 |
PURPOSE:To obtain the titled steel pipe of superior weld zone quality at a high welding speed by performing electric resistance welding at a strip edge butt part formed spirally by a tube making machine and then pressing it by a pressure roll before submerged arc welding. CONSTITUTION:A strip 1 is fed to three forming rolls 21 as shown by an arrow A and formed spirally, and its leading edge 2 and following edge 3 meet together at the rolls 21 to be resistance-welded. A welding current is supplied to edge parts by a contact tip 23. This weld zone 5 is pressed by a couple of upper and lower pressure rolls 25 adjoining to the rolls 21 simultaneusly with or right after the welding. Thus, the edges 2 and 3 are butt-welded correctly and horizontally and the junction 5 is restrained from deforming to prevent shape faults of the tube such as offset and peaking. The rolls 25 have a bead shaping function and flatten rugged beads 7 in a groove 6. Consequently, submerged-arc welding from the outside and inside of the tube after an intermediate work tube 4 is cut to necessary length is carried out excellently at a high speed. |
