Research About The Theory Of Deep Drawing Process For A Rectangular Box Of Magnesium Alloy

As the characteristic of high specific strength, impact resistance and recycling ratesetc, magnesium alloy has been widely used in automotive, aerospace and3C products.Because of the hexagonal close-packed crystal structure, poor ductility of magnesiumalloy at room temperature and lower finished product ratio, it needs increasingtemperature to improve its plastic property. However, magnesium alloy was oxidizedeasily and the forming quality was greatly affected at high temperature. Compared withthe experiment and numerical simulation method, the theoretical method is the foundationto construct forming control, and also has great practicality and effectiveness.In this paper, AZ31B magnesium alloy tensile test was carried out to obtain thestress-strain curves at different temperatures and different strain rates. After processing thedata, the constitutive equations that contained softening factor were obtained, which laidthe foundation for the stress analysis and critical BHF calculation of different regions ofbox-shaped pieces. As non-axisymmetric deep drawing parts, the fillet and straight edge ofbox-shaped pieces interacted, which produced induced shear stress to make deformationmore complicate when they deformated.In this paper, the induced shear stress was considered to analysis the stress of flangearea and sidewall areas. Combined with magnesium alloy constitutive equations, the stressexpressions of different regions were obtained. The critical BHF of crack and wrinklewere obtained with analytical method and energy method, which paved the way for sheetforming control of magnesium alloy.Taking the deep drawing of AZ31B magnesium alloy box-shaped pieces as example,the stress distribution and critical BHF of flange wrinkle and sidewall crack werecalculated through MATLAB software according to the result of theoretical analysis. Andthe relationship between critical BHF and drawing stroke was discussed.