Characterization of Failure Mechanisms in Cross Wedge Rolling

Cross wedge rolling (CWR) is a metal processing technology in which a heated cylindrical billet is plastically deformed into an axisymmetric part by the action of wedge shape dies moving tangentially relative to the workpiece. The CWR process offers several innovative and unique features over traditional machining operations. Despite these advantages, the CWR process has not been widely accepted throughout the manufacturing community, particularly in the U.S. This can mainly be attributed to complexities involved in CWR tool design. The design of CWR tooling is difficult because of the potential failure mechanisms that can be encountered during the CWR process. In this dissertation, extensive experimental investigation and numerical simulation have been performed to characterize the major failure mechanisms in cross wedge rolling. Based on the combined experimental and numerical analysis, criteria for predicting improperly formed workpiece cross section due to excess interfacial slip and internal defects due to the formation of internal voids have been determined. Based on these criteria, it is believed that the design of CWR tooling can be simplified, making CWR a more viable manufacturing process in the US.