PURPOSE: To perform adequately automatic welding in a narrow part by exciting a copying roll and providing a restoring characteristic to a weld line by making use of the floating when the roll is excited.
CONSTITUTION: When the copying position of a copying roll 13 deviates, the roll is oscillated by an exciter 17 and therefore a welding torch 12 is pressed to a frame body 11 and rotates around a rotary joint 22. The rotating amt. of the joint 22 is detected with a displacement detector 24, and a driving motor 26 operates in accordance with the signal of said detector. When the center of the excitation moves, the roll 13 floats from the body 11; at the same time, the roll is moved to rotate around a contact point 16 by the energizing force of a spring 19, by which the central position of the torch is lowered. The roll 13 is finally brought into uniform contact with the body 11 by the operation of the next excitation cycle. In other words, the effect of restoring the position to the prescribed welding center is obtd. even if the roll 13 deviates in copying to the right or left direction.
MANABE YUKIO
AOKI MASAHIRO
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