Analysis of interfacial slip in cross-wedge rolling: a numerical and phenomenological investigation

Friction and slip between the workpiece and the tool in metal forming proce sses are important issues in tool design and product development. This pape r characterizes the tool-workpiece interfacial slip in a hat-wedge cross-we dge rolling process (CWR) using an explicit dynamic finite element method. An experimentally validated finite-element model of CWR is used to investig ate the effects of the friction coefficient, the forming angle, and the are a reduction on the tool-workpiece interfacial slip. A total of 14 rolling c onditions are analyzed. An analytical CWR model for the workpiece rotationa l condition, which predicts the onset of rotation, is derived. Using this m odel, the critical area reduction and friction coefficient are compared wit h the failure conditions that occurred in the finite-element modeling and t he prototype experiments. The variation of interfacial slip with CWR design parameters is found to provide insight regarding the CWR process design. ( C) 2000 Published by Elsevier Science S.A. All rights reserved.