Abstract: While a laser-beam application position is moved along a locus which circularly or elliptically circles around a locus center so as to cross a weld line that is a boundary between a first metal plate and a second metal plate overlapped with each other, the locus center is moved in a direction parallel to a weld line. A moving direction of the laser-beam application position is set such that the laser beam is first applied to the first metal plate and then to the second metal plate when the laser beam passes through an unmelted zone of the first metal plate and the second metal plate. The unmelted zone is located downstream of a range through which the laser beam has already passed in the direction parallel to the weld line.

Abstract: A welding method according to the invention is a welding method in which welding is performed by emitting a high-energy beam onto a welding object that includes a plurality of overlapped metal sheets. This welding method includes forming a tack weld nugget at a welding point on the welding object, and forming a plurality of final weld nuggets along a virtual closed curve that encircles the tack weld nugget, while leaving the tack weld nugget, at the welding point.

Abstract: A welding method according to the present invention is a welding method for irradiating an object to be welded including a plurality of metallic plates that are stacked on each other with a high energy beam and performing welding. The welding method includes: forming a plurality of tack weld nuggets along a virtual closed curve on a part to be welded of the object to be welded; and forming a plurality of main weld nuggets so that the main weld nuggets overlap the plurality of respective tack weld nuggets.

Abstract: Objects to be welded are joined together by laser welding to form adjacent nuggets. When a distance between central axes of the adjacent nuggets is p and a diameter of the adjacent nuggets in the objects to be welded is d, the adjacent nuggets are formed so as to satisfy an equation 1.0<p/d?1.6.

Abstract: A laser welding method includes: projecting a laser beam onto irradiation regions on plural metallic workpieces such that a weld section is formed when the workpieces are joined by laser welding, the weld section being formed of plural nuggets, and each of the irradiation regions being formed with each of the nuggets. The nuggets are sequentially formed by sequentially projecting the laser beam onto the irradiation regions that respectively correspond to the nuggets. The laser beam is projected onto each of the irradiation regions such that an amount of input heat from the laser beam that is projected onto each of the irradiation regions to the workpiece is reduced as the nuggets are sequentially formed.

Abstract: A welding method according to the invention is a welding method in which welding is performed by emitting a high-energy beam onto a welding object that includes a plurality of overlapped metal sheets. This welding method includes forming a tack weld nugget at a welding point on the welding object, and forming a plurality of final weld nuggets along a virtual closed curve that encircles the tack weld nugget, while leaving the tack weld nugget, at the welding point.

Abstract: A welding method according to the present invention is a welding method for irradiating an object to be welded including a plurality of metallic plates that are stacked on each other with a high energy beam and performing welding. The welding method includes: forming a plurality of tack weld nuggets along a virtual closed curve on a part to be welded of the object to be welded; and forming a plurality of main weld nuggets so that the main weld nuggets overlap the plurality of respective tack weld nuggets.

Abstract: A laser welding method for welding a plurality of objects to be welded by applying a laser beam scanned by a scanning unit to the plurality of objects to be welded while moving the scanning unit in a welding direction along a welding path, the laser welding method including the steps of: performing a step of preliminary-fixation-welding on a predetermined place in the welding direction of the objects to be welded, and a step of main-welding on a place corresponding to the preliminarily-fixed place of the object to be welded within a scanning range of the scanning unit while moving the scanning unit. Further, when the place corresponding to the preliminarily-fixed place of the object to be welded is main-welded, the place is main-welded in a state where both sides of the place to be main-welded are restrained.

Abstract: A laser welding method includes: projecting a laser beam onto irradiation regions on plural metallic workpieces such that a weld section is formed when the workpieces are joined by laser welding, the weld section being formed of plural nuggets, and each of the irradiation regions being formed with each of the nuggets. The nuggets are sequentially formed by sequentially projecting the laser beam onto the irradiation regions that respectively correspond to the nuggets. The laser beam is projected onto each of the irradiation regions such that an amount of input heat from the laser beam that is projected onto each of the irradiation regions to the workpiece is reduced as the nuggets are sequentially formed.