| 摘要 |
PURPOSE:To generate proximity effect between weldments and to heat their weld zones efficiently by installing a conductor in a looped electric current circuit of welding current in high frequency welding of a metallic strip spirally to the surface of a metallic pipe. CONSTITUTION:While a metallic pipe 1 is rotated and moved in an axial direction, a metalic strip 2 is fed to the surface of the pipe 1, and high frequency electric current is supplied through joints 5a, 5b to conduct the current to the pipe 1 and the strip 2 with the contactors 6a, 6b at the leading ends thereof. The strip 2 is welded spirally to the surface of the pipe 1 at a weld point 4 while the strip is pressed with a roller 3. In this case, a conductor 8 is provided in the space 7 on the inner side of the looped current path formed by a part of the surface of the pipe 1 and the joints 5a, 5b. Induction current is flowed to the conductor 8 by the high frequency current flowing in the looped current circuit and proximity effect is generated between the high frequency currents flowing in the looped current circut, whereby the currents are concentrated at the parts 1', 2' opposite to the condutor 8 to heat the strip and the pipe powerfully and superior welding effect is generated. |
