Optimum die-surface design of gear-spline extrusions using a general surface model

In this paper, an integrated CAD/CAM/CAE method for the optimum die-surface design of a stream-lined die for straight-sided gear-spline extrusion has been proposed. The die surface is represented by a general surface model. By applying the upper-bound method and the variable metric optimisation scheme, parameters of the die surface, along with those of the velocity field, have been optimised with respect to the minimum extrusion-pressure required. The optimum die-surface was manufactured subsequently, using NC machining to produce the EDM electrode. Extrusion tests for straight-sided gear-splines were then performed, to obtain the extrusion load and the experimental grid-deformation, the theoretical predictions for gear-spline extrusion being found to be in close agreement with the experimental results. Finally, the optimum die-designs for various process conditions are suggested based on the results obtained by the proposed design method.