SPRINGBACK OF SHEET METAL AFTER PLANE STRAIN STRETCH-BENDING
SPRINGBACK OF SHEET METAL AFTER PLANE STRAIN STRETCH-BENDING
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发表时间：
2007
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通讯作者：
Zhang Dong-juan
中科院分区：
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作者：
Zhang Dong-juan
针对板料拉弯回弹问题，基于Hill屈服准则、指数硬化和平面应变假设，建立了板料拉弯回弹的数学模型。通过拉弯算例对模型进行了验证。研究了单位宽度拉深力、模具型面半径、摩擦力和各向异性对回弹的影响。结果表明，只有当中性面偏移量超过板料厚度的1/4时，增加拉伸力才能有效地控制回弹。弯曲半径越大，压边力的增加对控制板料回弹越有效。然而，拉伸力不能无限制地增加。其计算准则是外板层的有效应变不大于材料的极限应变。随着拉深力的增大，摩擦对板料回弹的影响越来越大。此外，各向异性对板料拉弯回弹也有影响。与有限元模拟结果的对比表明，数学模型的预测结果与有限元模拟结果吻合较好。
For the springback problem of sheet metal stretch-bending, a mathematical model was proposed based on Hill’s yielding criterion, exponential hardening and plane strain assumption. The model was validated by a stretch-bending example. The effects of stretching force per unit width, die profile radius, friction and anisotropy on the springback were studied. The results from the proposed model indicate that only if the shift distance of neutral surface exceeds one-fourth of sheet thickness, the increase of stretching force can control the springback effectively. Furthermore, the larger the bending radius, the more effective the increase of binder force in controling the sheet springback. However, the stretching force cannot increase without limit. Its calculation criterion is that the effective strain at the outer sheet layer is not greater than the material limit strain. It also shows that with the increase of stretching force, the friction has much larger influence on the sheet springback. Besides, the anisotropy also has effect on the sheet springback of stretch-bending. Comparison with FE simulation results shows that the predicted results by the mathematical model consist well with those by FEM.