PURPOSE: To enable welding of a steep inside corner part, by detecting short- circuited stat between a welding nozzle and a work to recognize a corner, and rotating the welding torch to non-short circuited state between the welding nozzle and work, and performing succeeding welding process.
CONSTITUTION: When a welding nozzle 2 comes into contact with a work 4, a relay 7 and a relay contact become on. At this time positive voltage is applied from a DC power source 12 to a timer circuit 9, and output of the timer circuit appears delaying by a time constant determined by a resistance R2 and a condenser C. With delay time of the timer set to a specified value, even when the distance between the welding nozzle 2 and work 4 is shortened, if the two separate within a specified time, welding is continued without regarding it as a corner part. When the shortened time exceeds a specified time, it is regarded as a corner part, and the movement of the welding torch and arc welding are suspended for a time to prevent interference between the welding torch and work 4. Then, the torch is rotated to be set in the direction of next welding, and succeeding welding is performed.
FUJII HAJIME
SATOU SHINOBU
NOHAYASHI SHIGEMI
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