The wall thickness eccentricity is one of the most important weaknesses that appears in seamless tubes production, since this imperfection is subsequently transferred downstream through the manufacturing stages until the final product. For this reason, in this article a finite element model of the rotary tube piercing (RTP) process is developed aimed at analysing the wall thickness eccentricity imperfection. Experimental data extracted from the industrial process is used for the validation of the model, including operational process variables like power consumption and process velocity, and deformation variables as elongation and longitudinal torsion, originated by axial and shear strain respectively. The cause of longitudinal torsion is also analysed. The two most important conclusions derived from this study are: (I) the longitudinal torsion of the tube is a crucial parameter for the correct model validation, and (II) the combined effect between the uneven temperature distribution of the billet and the plug bending deformation is identified as the major cause of the wall thickness eccentricity flaw.

中文翻译：

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应变相关有限元分析旋转管穿孔壁厚偏心度。

壁厚偏心率是无缝管生产中出现的最重要的弱点之一，因为这种缺陷随后会在整个制造阶段传递到下游，直到最终产品。因此，本文针对旋转壁穿孔（RTP）过程的有限元模型进行了开发，旨在分析壁厚偏心缺陷。从工业过程中提取的实验数据用于验证模型，包括分别由轴向应变和剪切应变引起的操作过程变量（如功耗和过程速度）以及变形变量（如伸长率和纵向扭转）。还分析了纵向扭转的原因。这项研究得出的两个最重要的结论是：