China Mechanical Engineering ›› 2021, Vol. 32 ›› Issue (21): 2635-2645.

### Investigation on End Circumferential Wrinkles of Large Deformation Pushing Diameter-reducing Tubes with Wall Thickness Deviation

LIU Heng1，2;WANG Liandong1，2;TAN Qiying2;WANG Xiaodi3;SONG Xiliang2

1. 1.Hebei Key Laboratory of Special Delivery Equipment，Yanshan University，Qinhuangdao，Hebei，066004
2.School of Vehicle and Energy，Yanshan University，Qinhuangdao，Hebei，066004
3.School of Mechanical Engineering，Yanshan University，Qinhuangdao，Hebei，066004
• Online:2021-11-10 Published:2021-11-25

### 带壁厚偏差管大变形推压缩径端部周向褶皱研究

1. 1.燕山大学河北省特种运载装备重点实验室，秦皇岛，066004
2.燕山大学车辆与能源学院，秦皇岛，066004
3.燕山大学机械工程学院，秦皇岛，066004
• 通讯作者: 王连东（通信作者），男，1967年生，教授、博士研究生导师。研究方向为液压胀形工艺理论与技术、汽车零部件设计及制造。E-mail：wld670509@163.com。
• 作者简介:刘恒，男，1989年生，博士研究生。研究方向为车辆关键零部件轻量化理论与技术。E-mail：liuhenghd@163.com。
• 基金资助:
河北省重大科技成果转化专项(20282202Z)；
河北省自然科学基金(E2016203352)

Abstract:  Circumferential winkles in inner wall of tube end during pushing diameter-reducing production practice would seriously affect the quality of parts. The wall thickness of seamless steel tubes was measured， and the distribution law of wall thickness along circumferential direction was alternately thin and thick. A mechanics model of pushing diameter-reducing of tubes with wall thickness deviation was established. The stress and deformation in reducing， rounded corner and exit stage were analyzed， and the generation mechanism of circumferential winkles at the ends was obtained. Four times pushing diameter-reducing tests of tubes with different wall thickness deviation were carried out. Results show that the end unevenness is greater than the initial one, and the sizing area unevenness is less than the initial one， which are consistent with theoretical analyses. The influence laws of wall thickness deviation and reducing times on unevenness and relative unevenness were summarized， and the ranges of process parameters for producing circumferential wrinkles were given. A geometrical model of tubes with wall thickness deviation was established， where the inner surface shapes were periodic sinusoidal variation and the outer surface shapes were circle. The generation and development of circumferential winkle were  simulated， the evolution laws of wall thickness and relative unevenness in each stages were obtained. Simulation results show that  theoretical analyses are consistent with the tests. By means of pushing-pulling diameter-reducing， the end unevenness and warpage may be greatly reduced， and the forming quality may be effectively improved.

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