Method and apparatus for composite YAG laser/arc welding

A composite YAG laser/arc welding method comprising the steps of

• disposing an arc electrode so that it targets a point on a member being welded which is irradiated by a laser beam from a YAG laser;
• connecting an arc power supply of a no-load voltage between the arc electrode and the member being welded,
• irradiating the member being welded with the laser beam from the YAG laser to produce plasmoid gasses and metal vapors which are effective to start an arc from the arc electrode which is connected to the arc power supply of a no-load voltage;
• and maintaining the plasmoid gasses and metal vapors which are produced by the irradiation by the YAG laser within and around a keyhole in a member being welded created by the YAG laser to provide a combined use of the YAG laser and the arc to perform a welding operation,
• wherein a welded surface of the member being welded is covered by a hood, the interior of which is partitioned by a gas commutating body having a multitude of openings into a welding space located toward the welded surface and a gas supply space, and in which the member is irradiated by the YAG laser through openings formed in the hood and the gas commutating body, a shield gas being supplied to the gas supply space and passed through the gas commutating body to provide a shield gas atmosphere around a point irradiated by the laser and the tip of the arc electrode while suppressing a disturbance of plasmoid gasses and metal vapors within the keyhole by the shield gas.