Estimation of Upper Bound Loads for Extrusion and Coining Operations

The pressure required for certain extrusion and coining operations may be approximately estimated from a knowledge of that required to perform the analogous operations under conditions of plane strain, and these pressures may be closely over-estimated by the use of a principle due to Hill or a Limit Theorem of Drucker, Greenberg, and Prager. Numerous examples are presented of a graphical or primarily non-analytical approach for closely over-estimating extrusion or coining loads required. The solutions presented give insight into the mechanics of certain metal-working operations and give good approximate results for problems generally solved by the lengthy numerical procedures associated with the use of slip-line fields.