Verfahren und Vorrichtung zum Rundbiegen von Buchsen

摘要

The invention concerns a rounding device (10) comprising two shaping dies (12, 14) with shaping chambers (22, 24) in order to round a sheet bar (26) about a core (16). The peripheral lengths of the two shaping chambers (22, 24) are each longer than half the can length. During a shaping step, the core (16) penetrates a first shaping chamber (22) by a depth which is greater than the can radius. The sheet bar (26) is thus shaped in the form of a U. In an intermediate shaping stage, an auxiliary core (18) is placed on the core (16) such that, as the second shaping die (14) moves downwards, only the ends of the U-legs of the sheet bar blank (26) are shaped arcuately. When the auxiliary core (18) and part (20) of the first shaping die (12) have been removed, the final can shaping process occurs, in which the second shaping die (14) likewise travels over the centre of the can. The three-stage rounding method enables cans to be rounded highly accurately and carefully.