| 摘要 |
PURPOSE:To manufacture a motorcycle rim excellent in metallic luster, by working an Al-Zn-Mg alloy extruded shape into rim shape and subjecting the surface of the above to shot peening treatment, solution heat treatment, and anodic oxidation film treatment. CONSTITUTION:An Al-Zn-Mg alloy ingot is extruded to be formed into an extruded shape having the prescribed rim section, which is used as a stock and subjected to working such as spiral bending, etc., so as to be formed into a rough rim with the prescribed rim shape. Then, shot peening is applied to the rough rim to form a hardened layer on the surface. As to the above shot peening treatment, it is preferable that grains of about 50-500mum grain size are blown at about 1-10kg/cm<2> pressure for about 10-60sec so as to obtain the desired work-hardened layer. Subsequently, solution heat treatment is applied to the rough rim at about 450-550 deg.C for about 10min- several hours to form the above hardened layer into recrystallized structure. Further, after subjected to prescribed buffing and chemical polishing, if necessary, the above rough rim is subjected to anodic oxidation film treatment so as to be formed into a motorcycle rim.
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