To obtain, through welding in a short time, an end face having the shape which facilitates insertion of a test tool or the like into a tubular body by moving the welding head of twin beams along the end face of the tubular body in a manner that two places are simultaneously welded in the end face and in the width direction of the tubular body.
In welding a tubular body 2 to a tube plate 1, a welding head provided with an optical system for obtaining twin beams for which a laser beam emitted from an optical fiber 11 is split into two optical paths of laser beams B, Bd, is moved along the end face of the tubular body 2 in the manner that its two places of the end face are simultaneously welded in the thickness direction. As a result, since a groove and a corner can be welded at the same time on the end face of the tubular body, the welding is finished in a short time and also the end face has such a rounded shape as test tools can be inserted without difficulty. In addition, the twin beams can be converged on the end face of the tubular body with a space apart in accordance with the thickness on the surface of a workpiece, enabling the welding to be simultaneously performed regardless of the thickness of the tubular body.
HASHIMOTO YOSHIO
SHIMOKUSU YOSHIAKI
AKAHA TAKASHI
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