| 摘要 |
PURPOSE:To make arc length constant stably without contact between electrodes and base materials and without hunting phenomena by detecting the arc voltage on the side where a wire is not fed independently, and changing the feed rate of the wire so that the arc length coincides with a set value. CONSTITUTION:In a multiple electrodes TIG welding method wherein welding currents are flowed alternately to respective electrodes, a voltage is applied to a differential amplifier 10 through a low-pass filter 16 to remove the high frequency components by switching and only the fluctuating components of the arc voltage are detected. In the voltage detection, the voltage between D and B where a wire is not fed is detected, and the feed rate of the wire is changed or a torch 2 is moved vertically until the set voltage (arc length) is attained, whereby the arc length is maintained constant. Thus the arc length is maintained constant, and the contact of the electrodes with base materials and hunting phenomena are prevented. |
