PURPOSE: To maintain the feed speed for a wire adequately at all times irrespectively of welding currents and to obtain a good bead shape by welding the work at the welding speed in a prescribed range with respect to the feed speed for the wire.
CONSTITUTION: According to set arc currents, a function generator 30 sets an adequate feed speed for a wire and a motor 53 is driven according to the set speed, by which a wire 4 is fed to the side of base materials 9. The wire current is so set that the wire just melts and arrives at the materials 9 in accordance with the set feed speed for the wire and the signal for setting said wire current is obtained by conducting the output of the circuit 30 to the inside of a comparator 43 and setting a resistor 45 properly. The setting signal for the wire current is compared with the value obtained by converting the wire current detected by a wire current detector 37 properly to a voltage with an amplifier circuit 38 and a transistor 51 repeats on and off until the wire current value attains a prescribed value.
TABATA YOUICHIROU
SHIMIZU TAKAO
MIZUNO KOUJI
