| 摘要 |
PURPOSE:To obtain a large extent of reduction by working once without generating wrinkles, by reducing the opening end part of a cylindrical metallic can by use of a necking die which has formed the inside surface of its reducing part to a hollowed curved surface being symmetrical to the axis. CONSTITUTION:A cylindrical metallic can barrel 5 is fixed, and a guide ring 2, a necking die 1, a center core 3 and a holding body 4 are depressed simultaneously in the direction as indicated with an arrow. In this case, since an inside surface 1a' of a reducing part 1a of the die 1 is formed by a hollowed curved surface being symmetrical to the axis, whose inside diameter is decreased extending from an inlet part 9 to the inner part, an opening end part 5a is curved inward along the inside surface 1a' without separating from the inside surface 1a'. After an end 5a' has contacted with a stepped part 6, only the ring 2 and the die 1 are depressed, and a reduced part 5d having no wrinkles is obtained. |
