A Fast New Numerical Tool for Designing Pre-stressed Dies for Backward Extrusion: Part 1: Die Behaviour

Reported is an original and innovative method for the stress determination based on an analytical function of the process parameters for the backward extrusion process. Awarded the 2001 Thomas Stephen Prize by the Institution of Mechanical Engineers.Prestressed die inserts are often used in the forging of axisymmetric parts. Their use enhances overall tool economy and can enhance the quality of the finished forging. The design of tooling that incorporates prestressed die inserts is, however, complex. The complexity arises from the interrelated phenomena that occur within the dies during the forging process. As a result, it is not possible to obtain an analytical expression for critical parameters such as die stresses and deflections. This paper shows the limitations of currently used design methods, and identifies, for the backward extrusion process, which physical phenomena should be taken into account when designing prestressed tooling. (Professional Engineering Publishing