JPS57134271A - Starting method for welding - Google Patents

Abstract

PURPOSE:To start welding surely, and to prevent the generation of weld defects and communication disturbances owing to aerially radiated radio waves by providing a simple auxiliary electric power source circuit. CONSTITUTION:When a start switch S is closed, an electric motor controller 10 runs an electric motor 6 forward and a filler wire 5 is fed toward the work 3 by feed rolls 7. At this time, an auxiliary electric power source 8 generates an output as well, thereby applying the voltage to the extent of permitting the generation of arc discharge between the wire 5 and the work 3. When the leading end of the wire 5 contacts the work 3, short-circuiting current flows and this is detected with an auxiliary electric current detector 12. The auxiliary current conduction signal thereof is supplied to the control circuit 10, by which the polarity of the output thereof is inverted. The leading end of the wire 5 retreats from the work 3 and the short-circuiting is eliminated. At this moment, an auxiliary arc 13 is generated at the leading end of the wire 5, and the main welding arc supplied with electric power from a welding power source 4 is generated. Thereupon, the polarity of the output of the control circuit 10 is again inverted, then the motor 6 runs forward again, thereby feeding the wire 5 to the weld zone.