Laser welding method

A laser welding method comprising:

• irradiating a workpiece with a laser beam in a helical shape along a weld part of the workpiece,
• wherein the helical shape is a combination of a plurality of circular trajectories in which the laserbeam is moved circularly, and a movement trajectory in which the laser beam is moved in a proceeding direction along the weld part,
• a first energy of the laser beam in a front side of the workpiece in the proceeding direction in one circular trajectory of the plurality of circular trajectories as the first circular trajectory is larger than a second energy of the laser beam in a rear side of the workpiece in an opposite direction to the proceeding direction in the first circular trajectory, and
• a first rotation angle range in which the laser beam is irradiated with the first energy in the front side of the workpiece in the proceeding direction and a second rotation angle range in which the laser beam is irradiated with the second energy in the rear side of the workpiece in the opposite direction to the proceeding direction are provided in each of the plurality of circular trajectories as the first circular trajectory,
• wherein when assuming that the direction in which the rotation angle is 90° is the proceeding direction and that the rotation direction is clockwise rotation, a range of the first rotation angle is in the range of 180° to 0°, a range of the second rotation angle is in the range of 0° to 180°, and at least the first energy in the range of the first rotation angle is constant.

A laser welding method comprising:

• irradiating a workpiece with a laser beam in a helical shape along a weld part of the workpiece,
• wherein the helical shape is a combination of a plurality of circular trajectories in which the laser beam is moved circularly, and a movement trajectory in which the laser beam is moved in a proceeding direction along the weld part,
• a first energy of the laser beam in a front side of the workpiece in the proceeding direction in one circular trajectory of the plurality of circular trajectories as a first circular trajectory is smaller than a second energy of the laser beam in a rear side of the workpiece in an opposite direction to the proceeding direction in the first circular trajectory, and
• a first rotation angle range in which the laser beam is irradiated with the first energy in the front side of the workpiece in the proceeding direction and a second rotation angle range in which the laser beam is irradiated with the second energy in the rear side of the workpiece in the opposite direction to the proceeding direction are provided in each of the plurality of circular trajectories as the first trajectory,
• wherein when assuming that the direction in which the rotation angle is 90° is the proceeding direction and that the rotation direction is clockwise rotation, a range of the first rotation angle is in the range of 180° to 0°, a range of the second rotation angle is in the range of 0° to 180°, and at least the first energy in the range of the first rotation angle is constant.