防皱多点成形及其误差分析

防皱多点成形是一种在调形单元之间布置防皱单元,使防皱单元与调形单元交错排列,从而在成形区内对板料表面进行约束,无需压边圈就可以产生防皱效果的多点成形方法。以球形件为例,运用有限元法针对起皱问题比较防皱多点成形和多点模具成形的成形效果。分析防皱多点成形在采用不同工艺参数时的成形误差,并探讨防皱多点成形对成形较小尺寸件的成形质量。研究发现,防皱多点成形方法能够很好地抑制板料在成形过程中的起皱现象;防皱多点成形时的球形件边缘的成形误差大于其内部区域的成形误差,减小防皱单元压力能够减小成形误差,但同时也会相应降低防皱单元的防皱能力;防皱多点成形采用头部具有转动自由度的单元能够增大单元与板料的接触面积,降低其成形误差;当防皱多点成形采用具有转动自由度的单元,并保证板料边缘外侧多设置一排单元时,成形件具有较高的成形质量。

Multi-point Forming with Wrinkle Resistance Function and Its Forming Accuracy

The main characteristic of multi-point forming with wrinkle resistance function is that the discrete holding punches arranged between forming punches hold the whole blank in the forming zone.The whole deformation stages of spherical part in this mode had been simulated,and the results are compared with multi-point die forming.The effects of varying technological parameters on shape error of part formed by this method are investigated.And the conclusion that the discrete holder punches contribute to wrinkle resistance,and the thinner the blank,the better the formability;the shape error in edges is larger than that in inner zone,decreasing the force of holder punches can decrease the shape error,but the capacity of wrinkle resistance is also reduced in the same time;the shape error can be reduced when punches with rote degree and large radius are adopted;this mode has high forming accuracy for smaller part than size of the die.