板材冲压翻边的解析理论模型

基于全量塑性理论及膜应变假设，给出两种新的冲压板材内曲拉伸／外曲收缩翻边坯料尺寸预示解析数学模型。引入板材冲压成形性分析软件KMAS系统中，对铁路客车牵引架实际冲压件的翻边成形坯料尺寸进行了预示，并与其它解析模型的预示结果以及实验及实测数据进行了对比。讨论了板材的面内各向异性对翻边高度的影响。

ANALYTICAL MODELS OF FLANGING PROBLEM OF SHEET METALS

The basic working procedures of automobile panel forming are drawing, trimming and flanging. For the needs of welding and assembling procedures, the most automobile panels need flanging after drawing process. Blank's shape and size after trimming is an important influencing factor for flanging, and also one of the key technique difficulties in sheet metals' stamping forming. There are two main aspects of flanging problem. The first is the prediction of wrinkling and fracturing in flanging forming, that is to say, studying the effect of flanging die geometry size on flanging formability, with the fixedness of sheet metals' thickness, material's parameter and flanging profile curvature. The second is how to definitely decide the position of trimming line, that is to say, deciding the blank's shape and size before flanging and making the flange height reach the required quantity, with the fixedness of flanging condition and height. Two new analytical models for concave shrink and convex stretch flanging of sheet metals with blank size prediction are proposed, based on the assumption of total plasticity theory and membrane strain. The models were introduced into independently developed KMAS software for sheet metal forming simulations in order to predict the blank shape and size of a thickness metal blank of rolling-stock's retractor and to verify its flanging height. The predicted and verified results of the present models and other analytical models in references are compared with corresponding experimental ones. Finally, influence of anisotropy of sheet metals on the flanging heights is also discussed.