| 摘要 |
PURPOSE:To keep the arc length constantly even with the variation in welding conditions by making the arc voltage of after the lapse of a certain time from the rise of the arc voltage a reference voltage and by moving vertically a tungsten electrode based thereupon. CONSTITUTION:An arc 5 is generated between the tungsten electrode 1 of a torch 4 and a base metal 2 and the arc voltage which is in the condition of the arc length l of immediately before a welding head starting to move is measured and stored into an AVC device 13 as the reference voltage of AVC. In this case the effect of the ripple of a power source 3 is removed by measuring the mean voltage for about 0.1-1.0sec by the reference voltage. When the welding is started with moving the head the torch 4 is moved vertically by the driving motor 14 of AVC so as to enter the reference voltage and the arc voltage under welding within the fixed range to control so as to make the arc length constant. A nearly fixed arc length is thus maintained even with the variation in the welding conditions of the shape and diameter of the electrode 1, the shielding gas flow quantity, the quality of the base material 2, etc. |
