Patent ID: 7999208

Claim:
A robot control unit for controlling a position of a welding torch in a tandem arc welding system, the welding torch having a leading electrode and a trailing electrode at a tip of the torch, wherein the robot weaves the welding torch right and left with respect to a travelling direction of welding, and a leading electrode power supply and a trailing electrode power supply are provided for supplying power to the leading electrode and the trailing electrode to perform arc welding along a weld line, the robot control unit comprising: a leading electrode detection section for detecting a quantity of a welding state during weaving of the leading electrode; a trailing electrode detection section for detecting a quantity of the welding state during weaving of the trailing electrode; a leading electrode processing section for calculating amounts of electrical change from the quantity of the welding state detected by the leading electrode detection section; a leading electrode correction means for calculating correction amounts for correcting a displacement in horizontal and vertical directions from the weld line of a weaving center trajectory to reduce the deviation of displacement of the weaving center trajectory, based on the amounts of electrical change calculated by the leading electrode processing section; a trailing electrode processing section for calculating an amount of electrical change from the quantity of the welding state detected by the trailing electrode detection section; and a trailing electrode correction means for calculating a correction amount for correcting a displacement in a rotational direction from the weld line of the weaving center trajectory to reduce the deviation from the weaving center trajectory, based on the amount of electrical change calculated by the trailing electrode processing section.