Abstract: A front flange portion formed at an outer peripheral edge portion of a wheel disc includes an annular front peripheral portion provided on a design surface side and an annular back peripheral portion folded backward from the annular front peripheral portion to extend radially inwardly and in surface contact with a back surface of the annular front peripheral portion, and the annular front peripheral portion and the annular back peripheral portion are integrally inclined to the surface side. Therefore, the front flange portion can mitigate stress concentration on the front flange portion due to a load generated while the automobile is running. In addition, the front flange portion has, because of its shape, high durability against a radially inward load generated by a contact with a curbstone or the like.

Abstract: An inner peripheral end portion of an annular back peripheral portion forming a front flange portion, an opening end portion of a front bead seat portion and a back surface portion of a wheel disc are joined to each other by a first welded portion and a second welded portion. Accordingly, it is possible to prevent the front flange portion from being repeatedly elastically deformed by loads generated while the automobile is running. In addition, it is possible to mitigate a stress concentration generated on the front flange portion and the first welded portion and the second welded portion. Thus, an automobile wheel can exhibit high durability.

Abstract: In an automobile wheel, a surface-side flange is provided on an outer circumferential edge of a wheel disk. The surface-side flange includes: a surface-side annular circumferential portion on an aesthetic surface; and a back-side annular circumferential portion that is formed continuously with, and on the back side of, the surface-side annular circumferential portion and that is thinner than the surface-side annular circumferential portion. An inner circumferential end of the back-side annular circumferential portion of the surface-side flange and an opening end of a surface-side bead seat of a wheel rim are welded together all along their circumferences. The automobile wheel allows the back-side annular circumferential portion of the surface-side flange to bear a stress that acts on a weld area. This relaxes the stress concentration on the weld area.

Abstract: Because a front flange portion including an annular front peripheral portion and an annular back peripheral portion is formed along an outer peripheral edge portion of the wheel disc, and because a back surface portion and an opening end portion of a front bead seat portion of a wheel rim are welded to each other over the entire circumference of the wheel but the annular back peripheral portion and the wheel rim are not welded to each other, stress concentration on the front flange portion due to a load generated while the automobile is running can be mitigated. Therefore, an automobile wheel has high durability against a load generated while the automobile is running.

Abstract: A front flange portion formed at an outer peripheral edge portion of a wheel disc includes an annular front peripheral portion provided on a design surface side and an annular back peripheral portion folded backward from the annular front peripheral portion to extend radially inwardly and in surface contact with a back surface of the annular from peripheral portion, and the annular front peripheral portion and the annular back peripheral portion are integrally inclined to the surface side. Therefore, the front flange portion can mitigate stress concentration on the front flange portion due to a load generated while the automobile is running. In addition, the front flange portion has, because of its shape, high durability against a radially inward load generated by a contact with a curbstone or the like.

Abstract: An inner peripheral end portion of an annular back peripheral portion forming a front flange portion, an opening end portion of a front bead seat portion and a back surface portion of a wheel disc are joined to each other by a first welded portion and a second welded portion. Accordingly, it is possible to prevent the front flange portion from being repeatedly elastically deformed by loads generated while the automobile is running. In addition, it is possible to mitigate a stress concentration generated on the front flange portion and the first welded portion and the second welded portion. Thus, an automobile wheel can exhibit high durability.

Abstract: In a disc of an automobile wheel, a plurality of hub surface rounded portions are formed at intervals on an imaginary circle provided around a hub hole and centered on an imaginary center corresponding to the center of the hub hole. The hub surface rounded portions are provided with a compressive residual stress by a compression process for work hardening. The strength of the hub surface rounded portions can thus be improved.

Abstract: In an automobile wheel, a surface-side flange is provided on an outer circumferential edge of a wheel disk. The surface-side flange includes: a surface-side annular circumferential portion on an aesthetic surface; and a back-side annular circumferential portion that is formed continuously with, and on the back side of, the surface-side annular circumferential portion and that is thinner than the surface-side annular circumferential portion. An inner circumferential end of the back-side annular circumferential portion of the surface-side flange and an opening end of a surface-side bead seat of a wheel rim are welded together all along their circumferences. The automobile wheel allows the back-side annular circumferential portion of the surface-side flange to bear a stress that acts on a weld area. This relaxes the stress concentration on the weld area.