Automatic weld line following method

Claim 1

In an arc welding method for welding a work by feeding a consumable electrode toward the weld line of said work through the tip of a welding torch and by oscillating said welding torch, a method for automatically following said weld line comprising the steps of: detecting average and effective values of a welding current, a consumable electrode feeding speed and a voltage between said tip and said work; arithmetically processing the detected quantities by means of a computer to determine a distance L (L=L E +L A ) between said tip and a weld metal which is equal to the sum of an arc length L A and the extension L E of said consumable electrode extending from the tip of said welding torch; detecting the deviation between the oscillation center of said welding torch and the center of a joint, which is constructed of said work, from the difference in said distance L between said tip and said weld metal in at least two predetermined oscillation positions; and controlling the position of said torch at all times so that the positional relationship between said oscillation center and said joint center corresponds to a predetermined relationship, whereby an arc point can automatically follow said weld line.