| 摘要 |
PURPOSE:To generate no wrinkle of a neck part, and to enlarge a neck-in depth by executing a necking working so as to draw an inclined reduced diameter part, in a state that a neck end part and a drum part of a cylindrical body to be worked have been pressed down. CONSTITUTION:A necking working part 6 having a neck end forming surface part 7 formed so as to increase gradually an overhang quantity (m) and a pressing surface part 8 is provided on an inside surface 5 of an external die 2, and an internal die 3 is formed by installing a pressing mandrel 11 and a neck end forming mandrel 12 to a rotary shaft 10. Subsequently, with respect to a working part 6, the inside surface of the opening end of a cylindrical body to be worked (a) is pressed down by a necessary surface pressure against a surface part 8, also the neck end forming part of the cylindrical body (a) is pressed down by a necessary surface pressure against the surface part 7, varying an eccentric quantity of the mandrel 12, the inclined part of the neck part of the cylindrical body (a) is drawn, and the die 3 is rotated and worked. In this way, no wrinkle is generated in the neck part, and the neck-in depth can be enlarged. |
