Abstract: This is a method of forming a fracture start portion of a ductile metal part on an inner circumferential face of a through hole by irradiating laser to an opposing position of the inner circumferential face of the thorough hole of the ductile metal part having a predetermined through hole and by forming a large number of recess portions separated with a predetermined distance at a predetermined interval from one opening to the other opening of the through hole, in which a recess part is formed, instead of by focusing the laser exactly onto the inner circumferential face of the through hole, by irradiating it onto the inner circumferential face of the through hole while defocusing from the inner circumferential face of the through hole by a predetermined amount as well as by supplying an assist gas to a position of the laser irradiation, and the laser is moved linearly at a predetermined speed from one side opening to the other side opening on the inner circumferential face of the through hole while irradiatin

Abstract: A fracture surface treatment method of a fractured ductile metal part for treating fracture surfaces 51a and 52a of the ductile metal part 50, said fracture surfaces 51a and 52a being fracture surfaces obtained by a fracturing operation of fitting halved mandrel portions into a penetrative bore of the ductile metal part having the penetrative bore and driving a wedge in between the halved mandrel portions, said fracture surface treatment method holding said fractured ductile metal part 50 in a state where said fracture surfaces 51a and 52a are separated from each other so as to keep a certain space between them, applying a specified vibration to at least one of said fractured ductile metal part portions in a direction intersecting the direction of fracture and removing fracture powder 59 stuck on said fracture surfaces 51a and 52a, and thereby enabling the optimum face fitting operation in case of fitting again the fracture surfaces of the fractured ductile metal part to each other.

Abstract: A fracture surface treatment method of a fractured ductile metal part for treating fracture surfaces 51a and 52a of the ductile metal part 50, said fracture surfaces 51a and 52a being fracture surfaces obtained by a fracturing operation of fitting halved mandrel portions into a penetrative bore of the ductile metal part having the penetrative bore and driving a wedge in between the halved mandrel portions, said fracture surface treatment method holding said fractured ductile metal part 50 in a state where said fracture surfaces 51a and 52a are separated from each other so as to keep a certain space between them, applying a specified vibration to at least one of said fractured ductile metal part portions in a direction intersecting the direction of fracture and removing fracture powder 59 stuck on said fracture surfaces 51a and 52a, and thereby enabling the optimum face fitting operation in case of fitting again the fracture surfaces of the fractured ductile metal part to each other.