Influence of die parameters on internal voids during multi-wedge-multi-pass cross-wedge rolling
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ORIGINAL ARTICLE
Influence of die parameters on internal voids during multi-wedge-multi-pass cross-wedge rolling Zhi Jia 1,2 & Jinjin Ji 3 & Yanjiang Wang 1 & Baolin Wei 1 Received: 13 April 2020 / Accepted: 9 August 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract The formation of internal voids in workpieces during cross-wedge rolling affects die design and limits their widespread applications. This article investigated the formation of internal voids during the multi-wedge-multi-pass rolling production of connecting rods. A three-dimensional numerical simulation model of cross-wedge rolling (CWR) was established using the rigid-plastic finite element method, and a density change model of the porous material was developed to characterize the degree of internal void formation in the connecting rod during CWR. The optimal die parameters (forming angle, spreading angle, and distribution coefficient of area reduction) were determined by determining their relationship to the density. The stress and strain of characteristic points near the loose longitudinal sections were used to study the void formation mechanisms. The accuracy of the numerical simulations was verified by rolling experiments, which showed no void formation in the internal sections of the connecting rod after production, confirming the feasibility of using this scheme to prevent void formation. Keywords Cross-wedge rolling . Porous material . Die parameters . Internal voids
1 Introduction Cross-wedge rolling (CWR) is an advanced method for forming plastic materials. It has characteristics of high production efficiency, low noise pollution, good production environment, strong equipment versatility, and low production costs. An increasing number of shafts have achieved near-net-shape production using CWR [1–5], and it is also used to make billets in some forging production processes. Although this process has greatly improved production efficiency and product quality [6], materials are subjected to three-dimensional, large-scale deformation and unsteady flow during CWR. Compression, stretching, bending, shearing, twisting, and
* Zhi Jia [email protected] 1
School of Material Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China
2
State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, No. 287 Langongping Road, Qilihe District, Lanzhou 730050, China
3
School of Materials Engineering, Lanzhou Institute of Technology, Lanzhou 730050, China
other deformation modes periodically occur in the deformation body [7]. CWR has a variety of limitations that restrict its widespread applications [8, 9], the most important of which is the formation of internal voids during the forming process, which makes it difficult to design CWR dies. Although much CWR research has focused on the plastic deformation mechanism of the workpiece, the evolution of macro- and microstructures, mechanical relationships, and defect generation mechanism during deformation, t
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