液室压力对异形长法兰盒形件充液成形过程的影响

异形长法兰盒形件由于法兰面积大,拉深成形时法兰区的材料流动困难,易出现开裂缺陷。通过对比分析壁厚分布的试验与仿真结果,证明了仿真分析具有可靠的准确度。利用实验与仿真相结合的分析方法,分析异形长法兰盒形件充液成形过程中初始反胀与成形压力的影响机理,优化液室压力加载路径,建立关于初始反胀压力与初始反胀高度的工艺窗口,用于指导该类零件初始反胀参数选取。分析结果表明:异形长法兰盒形件充液成形过程中,初始反胀压力与初始反胀高度过小,导致异形长法兰盒形件凸模圆角处破裂,初始反胀压力与初始反胀高度过大,导致异形长法兰盒形件凹模圆角处破裂;最大减薄率随着成形压力的增加,先减小后增加。

Influence of cavity pressure on box-shaped part with special-shaped long flanges in hydroforming process

Box-shaped part with special-shaped long flanges ( BPSLF) is difficult to form and easy to crack because the flange area is too large to make the materials in the flanges flow difficultly. Compared simulation of wall thickness distribution with the experiment results, the simulation agrees with the experimental results well. The influences of cavity pressure and initial pre-bulging in the hydroforming of BPSLF were analyzed combining experiment result with simulation result. The loading path of cavity pressure was optimized. The process window about the pre-bulging pressure and pre-bulging height was built to guide the selection of pre-bulging parameters of this kind of parts. The results show that when the pre-bulging pressure and pre-bulging height is too small, the BPSLF will rupture at the round corner of punch. While, the pre-bulging pressure and pre-bulging height are too large, the BPSLF will rupture at die corner. With increasing forming pressure, the maximum thinning rate decreases at first and then increases.