Patent ID: 8383986

Claim:
An arc start control method in robot welding comprising the steps of: shorting a welding wire with a base metal while applying a short-circuit current; retracting a welding torch by a welding robot for taking the welding wire off the base metal to generate an initial arc; retracting the welding torch to a predetermined position with the initial arc maintained while applying an initial arc current smaller than a steady welding current during an initial arc period; and starting to feed the welding wire steadily and to supply the steady welding current so as to make a transition from the initial arc to a steady arc as well as starting to move the welding torch along a welding line, applying a re-shorting prevention current, which is larger than the short-circuit current and the initial arc current, during a re-shorting prevention period, which starts when the welding torch retracts to a position for forming a gap between the welding wire and the base metal, in order to prevent re-shorting between a tip of the wire and the base metal right after the initial arc was generated, and thereafter, applying the initial arc current; increasing a welding voltage continuously at a first rate while maintaining a welding current at the re-shorting prevention current during the re-shorting prevention period; and decreasing the welding current from the re-shorting prevention current to the initial arc current to terminate the re-shorting prevention period and increasing the welding voltage continuously at a second rate that is lower than the first rate during the initial arc period.