| 摘要 |
PURPOSE:To perform stable welding in a wide current region with a stabilized arc length in pulse arc welding using an electrode fed at a constant speed by supplying pulse current at a constant current characteristic when an average welding current value is at a critical value or above and changing gradually a base current source or pulse current source to a constant voltage characteristic if said value is below. CONSTITUTION:Welding current is supplied from a base current control circuit 12 and a pulse current control circuit 11 through a tip T to a wire E. An arc length is stabilized by the self-control effect of the arc length occurring in a constant current characteristic if the welding current is at a critical current value determined by a welding condition or above. The amplification characteristics of characteristic varying circuits 15a, 15b are increased gradually by the current Io from a welding current detection circuit ID as the current value decreases to the critical current value or below, then the voltage difference Vr-Vo' from a set circuit 13 for a source output and a welding voltage detection circuit VD is amplified and is supplied as a signal to the circuit 11, which controls the pulse current gradually to a constant voltage characteristic thereby stabilizing the arc length. |
