| 摘要 |
The closure unit can be manufactured in a single deep-drawing operation. During the course of a predetermined stroke of the single deep-drawing operation, such as the downward stroke up to a lower dead-center position, a blank is punched out, a ring or marginal rim and a collar are formed, a central opening is punched out and a section extending peripherally to the cut edge is downwardly extended. During the upward stroke predetermined sections of the extended collar are rolled and subsequently squeezed together.
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