Needle-peening method

Abstract

A needle-peening method of peening a weld toe of a welded joint for welding and joining two pieces of sheet metal using a peening pin includes vibrating one or a plurality of the peening pins in a center axis direction; rotating the one peening pin about a single rotation axis parallel to the center axis while the center axis of the one peening pin is offset from the rotation axis, when using the one peening pin; rotating the plurality of the peening pins about the rotation axis, when using the plurality of the peening pins; and moving the one or plurality of the peening pins along the welding direction to peen the weld toe, wherein a radius of curvature of a cross section perpendicular to a welding direction at a distal end part of the peening pin is equal to or larger than 0.05 mm and smaller than 1.00 mm.

Dependencies are inferred from the claim text.