2001 Volume 41 Issue 3 Pages 268-274
Focusing on the rough forging stage of the hot free forging process, the influence of the operational conditions on the occurrence of concave defects was first numerically analyzed using a three dimensional rigidplastic finite element method. The validity of the analysis was examined by laboratory experiments using lead billets and the analytical results are in good agreement with experimental results. As a result, the mechanism through which the concave defects appear was clarified, and it was revealed that by applying only a small curvature to a plane surface of an anvil, the concave defects is enormously improved. Moreover, it was found that the new anvil geometry makes it possible to increase the productivity.