预成形型面对二道次渐进成形板厚分布的影响

为了研究预成形型面对金属板材二道次渐进成形板材厚度分布的影响,以直壁件两道次渐进成形为研究对象,首先制定了三种不同的预成形型面设计方案(型面轮廓线分别为圆弧和直线段),而后基于有限元模型分析了不同预成形型面条件下的板厚和等效塑性应变分布,并进行了实验验证.研究结果表明:半径为80 mm的圆弧状预成形型面侧面轮廓线可获得更均匀的板材厚度分布、更大的最小板材厚度、更小的等效塑性应变;二道次最小厚度分布并不取决于整个塑性变形区的大小,而决定于第二道次实际参与的变形区域大小,而该区域的大小决定于预成形型面的设计;最终板厚分布和预成形型面曲率并不存在线性关系,当切线夹角为40°左右时,板厚分布最均匀.
In order to study the influence of preformed shapes on the thickness distribution of double-pass incremental forming, based on the double-pass incremental forming of straight-wall part, three double-pass strategies with arc and straight line profile preformed shapes were designed. A finite element method (FEM) model of double-pass incremental forming was then established and experimentally verified. It is found that the double-pass strategy with a curved profile of curvature radius of 80 mm is expected to achieve less thickness reduction,equivalent plastic strain and larger minimum thickness. Additionally, the increased plastic deformation region does not always lead to larger thickness,and the final thickness is mostly related to the actual deformation area during the second pass that depends on the specific design of the preformed shape. Finally, a linear relationship between the curvature radius of the preformed shape and the final thickness distribution is not observed. When the tangential angle(θ) is around 40°,it has the most uniform thickness distribution.