Abstract: An electrode unit of a joining apparatus includes an abutting section provided with a tapered outer circumferential surface that contacts a tapered pressure-receiving surface by being inserted into an inside of a first metal member. The tapered outer circumferential surface inclines in a direction of getting closer to an axial center of the abutting section from one end side to another end side. At least part of the abutting section has a thickness elastically deformable in such a manner that the tapered outer circumferential surface aligns with the tapered pressure-receiving surface during application of a pressurizing force to the first metal member and a second metal member.

Abstract: A joining apparatus includes an electrifying/pressurizing head provided with an abutting surface contacting a pressure-receiving surface of a first metal member, joins the first metal member and a second metal member by electrification and pressurization employing the electrifying/pressurizing head, and obtains a joined body in which a joining interface inclines with respect to the pressure-receiving surface. The abutting surface includes: an electrode section capable of electrifying the first metal member; and an insulating section configured from an insulating material. At least a shortest portion where a distance from the joining interface will be shortest, of the pressure-receiving surface will be a non-contact-with-electrode section of non-contact with the electrode section, and the insulating section contacts at least part of the non-contact-with-electrode section.

Abstract: An electrode unit of a joining apparatus includes an abutting section provided with a tapered outer circumferential surface that contacts a tapered pressure-receiving surface by being inserted into an inside of a first metal member. The tapered outer circumferential surface inclines in a direction of getting closer to an axial center of the abutting section from one end side to another end side. At least part of the abutting section has a thickness elastically deformable in such a manner that the tapered outer circumferential surface aligns with the tapered pressure-receiving surface during application of a pressurizing force to the first metal member and a second metal member.

Abstract: A welded portion forming structure forms a welded portion that joins a valve seat and a cylinder head main body. If the distance in a radial direction between a vertex of a corner, which is formed by a first surface and a second surface of the convex portion, and the first origin portion is assumed to be A, and the distance in the radial direction between the vertex and the second origin portion is assumed to be B, then a relation that satisfies all of A>0, A?B, and B?0 holds. Moreover, an angle which a first joint surface of the valve seat forms with an axial direction and an angle which the second joint surface forms with the axial direction are equal.

Abstract: A casting die applied with laser machining and carbon-film coating on a die surface is provided with multiple grooves formed spaced at a predetermined pitch by the laser machining; multiple ridges between the multiple grooves; and multiple carbon portions buried in the multiple grooves by the carbon-film coating, wherein the die surface with the ridge and the carbon portion alternately disposed is configured such that molten metal flows thereon; the grooves are 45 ?m or less in opening width and 60 ?m or more in depth; and the ridge has, on a top surface thereof applied with the laser machining, multiple micro-grooves for reducing a contact area with the molten metal. The casting die is aimed to balance expanding the groove width and increasing a thickness of the carbon film and to achieve suppression of the molten metal entering into the groove and exfoliation of the carbon film.

Abstract: A casting die applied with laser machining and carbon-film coating on a die surface is provided with multiple grooves formed spaced at a predetermined pitch by the laser machining; multiple ridges between the multiple grooves; and multiple carbon portions buried in the multiple grooves by the carbon-film coating, wherein the die surface with the ridge and the carbon portion alternately disposed is configured such that molten metal flows thereon; the grooves are 45 ?m or less in opening width and 60 ?m or more in depth; and the ridge has, on a top surface thereof applied with the laser machining, multiple micro-grooves for reducing a contact area with the molten metal. The casting die is aimed to balance expanding the groove width and increasing a thickness of the carbon film and to achieve suppression of the molten metal entering into the groove and exfoliation of the carbon film.