Investigation on the inner hole spiral-groove of cross wedge rolling of hollow shafts with mandrel
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ORIGINAL ARTICLE
Investigation on the inner hole spiral-groove of cross wedge rolling of hollow shafts with mandrel Jinxia Shen 1 & Baoyu Wang 1,2 & Jing Zhou 1,2 & Longfei Lin 1 & Shengqiang Liu 1 & Pengni Feng 1 Received: 6 March 2020 / Accepted: 17 July 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract The cross wedge rolling (CWR) is an efficient and green process for manufacturing hollow shafts. The mandrel plays an important role in controlling hole shape during the process of hollow shafts CWR with mandrel. To obtain high-precision rolled parts, it is necessary to control dimensional fluctuations. Finite element (FE) simulation and CWR experiments were presented, and the results showed that the inner hole spiral-groove causes periodic fluctuations of inner diameter along axial direction and an uneven microstructure. The spiral-groove on the outer surface causes metal overlaps and cracks. The formation mechanism of the inner hole spiral-groove was studied. The inner hole spiral-groove is caused by the joint effect of CWR dies and mandrel. The formation reason of inner hole spiral-groove is that the metal in inner hole flows toward reverse-stretching direction under the effect of CWR dies and mandrel. The inner hole spiral-groove intensifies with the non-uniformity of instantaneous radial deformation. The effect of process parameters on the inner hole spiral-groove was investigated. The inner hole spiral-groove intensifies with the increasing forming angle, stretching angle, compress ratio, and initial pipe thickness. The inner hole spiralgroove decreases with the increasing relative mandrel diameter. The results reveal the reason of the inner hole spiral-groove of hollow shafts CWR with mandrel and provide theoretical guidance for the selecting of process parameters in production application. Keywords Cross wedge rolling . Hollow shaft . Mandrel . Spiral-groove . Dimension fluctuations
Highlights • The hole spiral-groove appears during CWR hollow shafts with mandrel. • The hole spiral-groove causes non-uniform of dimension and microstructure. • The hole spiral-groove is caused by the joint effect of CWR molds and mandrel. • Smoothing wedge-fillet does not completely remove the hole spiralgroove. • Reducing of the hole spiral-groove by coordinating appropriate process parameters. * Baoyu Wang [email protected] Jinxia Shen [email protected] 1
School of Mechanical Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, China
2
Beijing Laboratory of Modern Transportation Metal Materials and Processing Technology, No. 30 Xueyuan Road, Haidian District, Beijing 100083, China
1 Introduction The application of hollow shafts has become more and more widespread in machines with the development of lightweight structure. The hot net-shape forming technology of hollow shafts is necessary to reduce machining and to obtain hollow parts with well metal flow line [1]. Cross wedge rolling (CWR) [2–7] is an efficient, low-consumption, and
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