管材无模拉伸壁厚变化规律研究王忠堂，栾瑰馥，白光润，王景旭采用上限法对管材无模拉伸时壁厚变化规律进行了理论研究，提出了管材无模拉伸时壁厚变化与拉伸后管材外径、内径及截面收缩率之间的关系．通过实验研究证明，管材无模拉伸后壁原与其内径、外径以及人、又（Ｒ... Research on the law of the wall thickness variation of the pipe without die tensile Wang Zhongtang, Luan Guifei, Bai Guangrun, Wang Jingxu The wall thickness variation rule of the pipe without die drawing is studied by the upper bound method. Stretching pipe diameter, diameter and cross-section of the relationship between shrinkage. Through experimental studies have shown that the pipe without mold stretch after the original wall with its inner diameter, outer diameter and human, and (R ...