二辊斜轧实心圆坯三维有限元分析及中心孔腔形成机制

3-DIMENTIONAL FE ANALYSIS OF DEFORMATION OFTUBE ROUNDS DURING TWO-ROLL CROSS ROLLINGPROCESS AND CENTER CRACK MECHANISM

本文用ＭＡＲＣ／Ａｕｔｏｆｏｒｇｅ软件对圆坯二辊斜轧过程进行了三维热－力耦合弹塑性数值模拟，得到了轧件的变形强度分布形态及应力分布特征，研究了轧辊倾角包括送进角和辗轧角以及辊面推角对应力、应变场的影响，证实了变形强度沿圆坯断面直径上呈Ｗ形分布的试验研究结果，还发现了新的应变强度分布形态，即Ｕ型形态．在此基础上澄清了中心孔腔形成理论上存在的分歧，如管坯中心各正应力分量的大小关系、塑性变形的存在及其定量问题，并进一步讨论了中心孔腔形成的机制，认为塑性应变各分量沿管坯中心线的严重不均匀分布是诱发中心内撕裂的重要原因。

With the aid of FE code MARC/Autoforge, 3-D coupled thermo-mechanical analysesof round-billet during two-roll cross rolling process have been conducted and the distribution patternsof strain and stress in its deformation zone are presented. The influence of the feed angle, toe-in angleand the cone angle of the roll on the deformation and stress was investigated. The distribution pattern ofW-shaped over the diameter of the tube round as a result of experiment is further verified. Spontaneouslya new distribution pattern of U-shaped is discovered. Based on the above, some divergences of views on thetheory of inside-bore forming, such as the quantitative relation of every normal stresses and the quantity ofthe plastic deformation in the center of tube rounds, are all clarified. Furthermore the mechanism of centercrack occurrence is discussed and it is believed that seriously inhomogeneous distribution of normal plasticstrains along the centerline of the tube round is one of important causes for the center-crack occurrence.