Abstract The free bending technology is regarded as a promising fabricating technology in the recent years. Due to characteristics of complex product shape and dieless forming, this technology arises more and more attention recently. Firstly, this paper analyzed movement track of bending die based on the principle of free bending technology. Then, distribution characteristics of equivalent stress and strain on tube and bending die during different stages of the free bending process were analyzed. Afterwards, this paper studied the influence law of clearance between tube and bending die, fillet radius of guider, feeding speed on the tube free bending quality. Relationship between eccentricity U of bending die and bending radius R of tube relates to the bending program directly. In this paper, U-R relationship was obtained by finite element simulation to verify the accuracy of the built model. FE simulation and bending experiments were conducted based on the research results. The result revealed that dimension of the bent spatial tube was close to the CAD model and proved the reliability of U-R relationship. Deviation of the bending radius and bending angle is supposed to occur due to springback after forming.

中文翻译：

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空间管自由弯曲过程模拟与实验研究

摘要 自由弯曲技术是近年来被认为是一种很有前途的制造技术。由于产品形状复杂、无模成型等特点，该技术近来越来越受到重视。首先，基于自由弯曲技术的原理，分析了弯曲模具的运动轨迹。然后，分析了自由弯曲过程中不同阶段的等效应力应变在管子和弯曲模具上的分布特征。随后，本文研究了管材与弯曲模具的间隙、导向器的圆角半径、进给速度对管材自由弯曲质量的影响规律。折弯模具偏心距U与管材折弯半径R的关系直接关系到折弯程序。在本文中，通过有限元仿真得到UR关系，验证所建模型的准确性。根据研究结果进行了有限元模拟和弯曲实验。结果表明，弯曲空间管的尺寸与CAD模型接近，证明了UR关系的可靠性。弯曲半径和弯曲角度的偏差应该是由于成型后的回弹而发生的。