| 摘要 |
PURPOSE:To start instantaneously an arc and to improve workability and quality of welding by limiting the rising speed and peak value of starting current and starting the arc. CONSTITUTION:Starting current is risen at a high speed of >=30A/sec and the peak value is made >=100A in DC TIG arc welding, then the temp. of a tungsten electrode is quickly increased and the electrode is quickly made to hot cathode, by which the arc startability particularly in a small current region is remarkably improved. The rectangular waveform with which a peak value IP is attained simultaneously with starting and decreases down to the stationary welding current after the peak value is held for specified time is ideal for the waveform of the starting current in this stage but the delay in rising of the current owing to the reactance of a circuit, etc. is unavoidable. The actual waveform is therefore such that the peak value IP is attained with some inclination and thereafter the peak value decreases with the prescribed inclination down to the stationary welding current. |
