Patent 11052488 was granted and assigned to Toyota on July, 2021 by the United States Patent and Trademark Office.
A manufacturing method for a shaft 1 by imparting a residual compressive stress to an inner surface 4p of the lateral hole 4 of the workpiece 2 includes a disposing step and an irradiation step. In the disposing step, a lateral-hole mirror 14a is disposed inside the lateral hole 4. In the irradiation step, a laser beam L is emitted from one of an inner-side opening 4a and an outer-side opening 4b of the lateral hole 4 toward the lateral-hole mirror 14a, making the laser beam L reflect on the lateral-hole mirror 14a, and thereby applying the laser beam L to the inner surface 4p of the lateral hole 4.