Patent ID: 8627700

Claim:
A method of manufacturing a wheel rim for a vehicle comprising: forming a flange portion by bending an axial end portion of a tubular material made from steel in a direction crossing an axial direction of the tubular material, thereby forming in the tubular material a bent portion and the flange portion on a tip side of the bent portion, ironing the tubular material to a tubular member having a non-constant thickness using an ironing apparatus which has a punch, a die having a convex and concave surface opposing the punch and a pressing member, and roll-forming the tubular member having a non-constant thickness to a vehicle wheel rim configuration after the ironing, wherein the ironing comprises: setting the tubular material on the die at the flange portion of the tubular material; then moving the pressing member relative to the die thereby squeezing the flange portion of the tubular material between the pressing member and the die; and then, while the flange portion of the tubular material is squeezed between the pressing member and the die, moving the punch relative to the die thereby ironing at least a portion of the tubular material except the flange portion of the tubular material to manufacture the tubular member having a non-constant thickness, wherein at the roil-forming, at least a portion of the flange portion of the tubular material is formed to one of the flange portions of the rim of the wheel rim for a vehicle, and wherein the steps of forming the flange portion, ironing the tubular material, and roll-forming the tubular member are conducted in the order of forming the flange portion, ironing the tubular material, and roll-forming the tubular member.