| 摘要 |
The invention concerns a bending 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 bushing circumference. During a pre-shaping step, the core (16) penetrates a first chamber (22) by a depth which is greater than the bushing 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 end 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 bushing shaping process occurs, in which the second shaping die (14) likewise travels over the center of the bushing. The three-stage bending method enables a bushing to be rounded highly accurately and carefully.
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