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 processes are important issues in tool design and product development. This paper characterizes the tool-workpiece interfacial slip in a hat-wedge cross-wedge rolling process (CWR) using an explicit dynamic finite element method. An experimentally validated finite-element model of CWR is used to investigate the effects of the friction coefficient, the forming angle, and the area reduction on the tool-workpiece interfacial slip. A total of 14 rolling conditions are analyzed. An analytical CWR model for the workpiece rotational condition, which predicts the onset of rotation, is derived. Using this model, the critical area reduction and friction coefficient are compared with the failure conditions that occurred in the finite-element modeling and the 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.