| 摘要 |
PROBLEM TO BE SOLVED: To improve the yield of a material and obviate the need of cutting off processing by expanding one end of an annular rim blank, rounded a rim blank and weld-joined and successively, forming into the rim shape with plural steps of roll formings. SOLUTION: The necessary size of rim material is rounded and the butted ends are weld-joined to form the annular rim blank 11. The end part 16 at a flangeless side of the annular rim blank 11 remains as almost straight-state and a flaring work for expanding only the end part 17 at the reverse side is applied. The end part 16 at the almost straight side of the annular rim blank 11 is formed as the rim-shape with plural steps of roll-formings while butting to a butting ring 18 in the rim axial direction. Successively, the end part 16 at the flangeless side is sized by cutting and a valve piercing is executed and successively, the rim end part 16 is turning-worked. The end part 17 at the flaring side is rolling-formed to form the flange part 13. By this method, the trouble of scrap treatment is saved and one side flangeless wheel rim can be manufactured. |
