Nippon Light Metal Company, Ltd.

Masatoshi Namba

Takuo Kusano

Kouichi Masuda

The method for producing an aluminum wheel rim comprises axially pressing a thin walled cylindrical aluminum or aluminum alloy material under the action of compressive stress acting thereon through tapered portions of a die and a punch cooperating therewith in a press machine so that the diameter of the material is enlarged so as to form the required configuration of the rim, while the wall thickness of the material is increased at positions where compressive stress is applied through the tapered portions of the die and the punch thereby increasing the mechanical strength of the material at positions where otherwise weakening tends to occur due to the thinning of the wall thickness of the material by the roll working thereof. In order to successfully carry out the method, it is preferred to select the ratio H/D of the height H of the material with respect to the inner diameter D thereof to be equal to or less than 1.5, the ratio t/D of the wall thickness t of the material with respect to the inner diameter D to be in the range of 0.006 to 0.06 and the mean deformation resistance or mean flow stress of the material to be in the range of 10 to 25 kg/mm.sup.2, while the inclination angle of the tapered portions of the die and the punch is set to be in the range of 10.degree. to 65.degree..

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Tokyo, Japan

Masatoshi Namba