WELDING METHOD BY ROBOT

PURPOSE:To shorten the time in an instruction work by instructing a welding start point and the welding completion at distant point from the actual welding length by the direction to a robot and stopping the welding by detecting the shape change of a work with the variation in a welding voltage, etc., as well. CONSTITUTION:A current measuring instrument 21 is provided on the way of a cable at a work 4 side and the end part detector (a) of welding is arranged as well. The detector (a) detects the change in an impedance from the current, voltage value detected by the current measuring instrument 21 at the end of the work 4, inputs an output signal to a robot driving device (b) and stops a robot 1. The O mark of a start point and the black mark in a circle of a completion point are instructed as an instruction point 10 and plural instructions of A, B, C are performed by the welding direction. In case of welding ribs 14, 15 the welding of an actual welding length is performed via the signal of the detector (a) according to the programs A, B, C. Owing to the need to perform the instruction on each actual welding dimension being eliminated the instruction work time can be shortened.