| 摘要 |
PURPOSE:To eliminate the waste of a high frequency electric power source device by applying the high frequency voltage from a single high frequency electric power source selectively to plural consuming electrodes in accordance with the commands from the sensors which confirm the presence of objects to be welded. CONSTITUTION:According to the command from a phototube Ea1 which is the 1st sensor to confirm the presence of a steel pipe 7 first, a high frequency voltage is applied to the 1st electrode 1a among the electrodes 1a-1d, by which arcs are started. Thereafter, a high frequency voltage is applied to the 2nd electrode 1b installed with a phototube Ea2 in accordance with the command from the phototube Ea2 which is the 2nd sensor to confirm the presence of the pipe 7 in succession to the above, whereby the arcs are started. A high frequency power source 10 and a switching circuit 12 thereof for applying the high frequency voltages to the electrodes 1a-1d in accordance with the commands of the phototubes Ea1-Ea4, Eb1-Eb4 are disposed at the preceding end part of a boom 6 and a control circuit for controlling the switching thereof is provided in a control circuit 5. |
