Output control of short circuit welding power source

A method for controlling the output of a power source in consumable electrode arc welding in which a short circuiting phase and an arcing phase alternately take place between a consumable electrode and a workpiece in a shielding gas atmosphere, which comprises:

• a first stage of maintaining the output welding current at a first value at a relatively low level upon establishment of a short circuit across a gap between said consumable electrode and said workpiece;
• a second stage of maintaining the welding current at a second value at a relatively high level subsequent to the first stage;
• a third stage of lowering the welding current to a third value at a low level upon detection of necking as a premonition of rupture of short circuiting molten metal between said electrode and said workpiece;
• a fourth stage of, upon generation of an arc across said gap between said electrode and workpiece subsequent to the third stage, maintaining the welding current at a fourth value at a relatively high level exceeding the value of average welding current and controlling the duration of said high level current as a function of the feed rate of said consumable electrode;
• and
• a fifth stage of maintaining the welding current at a fifth value at a relatively low level until said gap between said electrode and workpiece is short-circuited, under control of substantially constant current characteristics so as to feed current of a constant level irrespective of variations in arc length.