アルミニウム極薄肉管のしごき加工におけるしわ発生機構

抄録

Wrinkling during the ironing of very thin wall aluminum cups has been investigated. Three types of wrinkly were observed on the finished cup wall, i. e., a circumferential single wrinkle, and short-and long-pitch wrinkles generated within the band areas of the wall. All are a kind of buckling at the die exit due to the axial compressive stress acting on the ironed wall metal. The enhancement of the stress is caused by the decrease in the die surface friction which is induced by a metal bulging just before the die entrance. The wrinkly type is thus subject to the bulging behaviour affected by the initial thickness of the cup and the ironing reduction ratio.