The deformation behavior of deep drawing of plate is different from that of sheet metal because of the obvious stress gradient along the thickness direction induced from bending effect. The finite element analyses were performed to investigate the radial stress during the plate deep drawing process,and the maximum radial stress and its location along die radius were observed, the effect of die radius on radial stress was discussed. An experiment was conducted on the deep drawing of 5A06 aluminum plate with thickness of 4.5 mm into the cups with diameter of 450 mm. The results show that the maximum radial stress generates at the transition area between the die radius and cylinder wall, and the fracture occurs at the same place. With increasing the die radius the maximum radial stress decreases. And cracks initiate at the transition area between the cylinder wall and die radius. The maximum radial stress decreases and the fracture is delayed when the die radius increases, as a result, the limited punch stroke at the relative die radius of 12 is improved by about 83% compared with that at the relative die radius of 4.5.%由于弯曲效应，中厚板拉深时厚度方向存在明显应力梯度，使其与薄板拉深变形有所不同。通过有限元数值模拟，研究中厚板拉深变形过程中不同阶段板材厚度方向的径向应力分布规律，揭示凹模圆角大小对中厚板拉深变形径向应力的影响规律。对厚度4.5 mm的5A06铝合金板材进行不同凹模圆角条件下内径为450 mm筒形件拉深实验研究。结果表明：中厚板拉深过程中最大径向应力位于直壁区与凹模圆角过渡处；且随凹模圆角的增大，最大径向应力值逐渐减小；破裂缺陷发生在凹模圆角与直壁区过渡处，且随凹模圆角增大，破裂延缓发生，极限拉深行程显著提高，凹模相对圆角为12时的极限深度比相对圆角4.5时的提高了83%。
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