| 摘要 |
PURPOSE:To prevent burr on the inside surface in the press weld parts in the stage of joining steel pipes by press welding by forming the press welding end parts of the steel pipes to a Y shaped groove, setting said parts specially and heating the root part of the groove by an electromagnetically driven arc and the tapered parts by a gas, thereby press welding the end parts. CONSTITUTION:In the stage of joining steel pipes 3-1 and 3-2 in the joining parts 4 of their end surfaces by press welding, a Y shaped groove is formed on each end surface to be welded and the end surfaces are set at a spacing l'. For heating the parts 4, the root part 4-2 of the Y shaped groove is heated by the arc 7 generated with an electric power source 11 for generation of arc while the arc 7 is rotated and moved at a high speed over the entire circumference of the root part by coils 12-1, 12-2 for electromagnetically driven arc. The joining part 4-1 on the outside surface that forms a taper 4b of the groove is heated with a burner 1. After heating the groove parts, the pipes 3-1 and 3-2 are joined by press welding the same at their end parts 4. The joined parts are free from burr and are superior as a steel 4. |
