汽车覆盖件模具凸型面拉延方法

针对汽车覆盖件这种具有复杂曲面特征的零件，在传统的全型面拉延成形方法基础上提出一种新的凸型面拉延成形方法。该方法根据拉延成形过程中凸、凹模工作型面上只有凸型面接触板料的特点，通过成形仿真获得全型面拉延的成形极限图(Forming limit diagram, FLD)和凸、凹模与板料的接触区域分布。然后将板料相对凸、凹模工作型面上的起皱区域及双面接触区域所对应的单元剔除，将单面接触区域中面积较小且形态狭长的单面接触区域合并转化为双面接触区域，同时将未转化的单面接触区域外周节点拟合成曲线后导入到CAD中对凸、凹模工作型面进行分割获得所需的凸型面。算例表明该方法在保证拉延成形质量的前提下可以有效地减小凸、凹模工作型面的面积，降低拉延模具的生产成本。

Method on Convex Surface Drawing for Automobile Panel

In view of automobile panel parts with complex surface, a new convex surface drawing method is put forth based on the traditional whole-surface drawing process. Considering that only the convex parts of punch and die working surface contact with blank during drawing, forming limit diagram(FLD) and the contact area distribution diagram between punch or die and blank are acquired through stamping simulation. The corresponding elements of wrinkle area and double-sided contact area are removed from the grid model, and the single-sided contact regions with small and lathy area are merged and convert into double-sided contact regions. The curves, each is fitted through the outermost nodes of the rest single-sided contact regions that aren’t merged, are imported into CAD to trim working surface of punch and die to obtain the convex surface, the example shows that the convex surface drawing process put forth can decrease the punch and die working surface area and it can reduce the production cost of the drawing die, while maintaining drawing quality.