薄板多点成形时不同的工艺方式对起皱的影响

Influence of different technologic modes on wrinkle in multi-point forming of thin sheet metal

采用有限元数值模拟手段针对多点成形过程中产生的起皱现象以及消除皱纹的措施进行了探讨.对比了多点模具成形和多点压机成形两种不同工艺,分析了不同的成形工艺条件对起皱的影响.用显式动力学软件对0.1 mm与0.5 mm厚度的马鞍型曲面件进行了数值模拟,结果表明,在多点模具成形方式下,采用无压边成形,使用弹性垫,成形0.5 mm厚度的板料时,曲率半径为100 mm的成形件起皱剧烈;但在相同条件下,用多点压机成形工艺的成形件结果良好,甚至成形厚度为0.1 mm的板料也没有起皱.表明多点压机成形方式比多点模具成形方式成形效果好,缺陷少,并且有利于板材的流动,能够得到更大的变形量.

FEA numerical simulation is used to simulate wrinkle and some measures are discussed to eliminate wrinkle. By contrasting the multi-point die（MPD） with multi-point press （MPP）, the influences of different forming modes on wrinkle are analyzed. Furthermore the forming processes of the saddle parts with the thickness of 0.1 and 0.5 mm were simulated by explicit software. Results indicate that the sheet metal with the thickness of 0.5 mm and curvature radius 100 mm sharply wrinkles in the MPD forming mode without blankhold and elastic cushion. Under the same condition good forming results can be obtained in the MPP forming mode, even in the thickness of 0.1 mm. All these indicate that MPP is a high efficiency forming mode, by which forming defects can be reduced. Sheet metal can easily flow in MPP and sheet metal parts with large curvature can be formed bv MPP.