电磁斜孔翻边的板料结构设计和变形规律研究

Research on sheet structural design and deformation law for electromagnetic oblique hole flanging

斜孔翻边被广泛应用于运载火箭燃料贮箱箱底,但现有工艺存在翻边破裂、高度不均匀和多套复杂工装等问题。利用电磁成形的单模具和可以提高材料成形极限的优势,实现了采用单套工装和线圈一次放电成形高精度的斜翻边孔。通过理论解析建立了板料不同区域翻边高度的计算公式,发现斜孔翻边的高度差与板料厚度t0和翻边圆角半径r有关。采用有限元仿真优化了椭圆孔圆心的偏置量,发现随着偏置量的增加,板料斜孔翻边的高度差先降低后增加,当偏置量为5 mm时,板料斜孔翻边后的最大高度差为0.20 mm。在电磁成形过程中,锐角侧先于钝角侧变形,而惯性效应会使得零件最终贴模。放电电压为10 kV条件下板料与模具的最大贴模间隙为0.25 mm,有限元仿真与实验结果的误差小于5%。

Oblique hole flanging is widely used in the bottom of carrier rocket fuel tank,but there are some problems such as cracked flanging,uneven height and multiple sets of complicated tooling in the existing technology.Therefore,utilizing the advantages of single die and improving the material forming limit of electromagnetic forming,the high precision oblique flanging hole was formed by a single set of tooling and coils in one electric discharge.The results show that the calculation formula of flanging height in different areas of sheet metal is established by theoretical analysis,and the height difference of oblique hole flanging is related to sheet metal thickness to and flanging fillet radius r.Using finite element simulation to optimize the offset of lliptic hole center,it is find that with the increasing of offset,the flanging height difference of sheet metal decreases first and then increases,and when the offset is 5 mm,the maximum height difference is O.20 mm after sheet metal oblique hole flanging.In the process of electromagnetic forming,the acute-angled side deforms before the obtuse-angled side,and the inertia effect leads eventual fitness to die of the part.At the discharge voltage of 10 kV,the maximum fit gap between sheet metal and die is 0.25 mm,and the error between the finite element simulation and the experiment results is less than 5%.