Optimum Design Of Die Cavity Surface For Aluminum Alloy Extrusion

During the aluminum alloy forming process, die cavity surface design is very important. If the die cavity surface shape is improper, the shearing force will be increased, the direction of metal flow near the die outlet will change rapidly, and the metal flow velocity will not be uniform. In order to avoid these problems and reduce the die pressure, the design of a suitable die cavity surface seems to be necessary.An extrusion flow model of aluminum alloy cylinder is built by the upper-bound method, the kinematically admissible velocity field, the strain rate field and the deformation power are deduced with five different die containers. In addition, aiming at reducing the extrusion power, the length of the die containers is optimized. FEM is used to simulate the extrusion process with the best die container length, and then the distribution of extrusion power and die contact stress are obtained. It can be seen that the theoretical results are in good accordance with the simulation results. The results show, with the best die container length and the same area reduction ratio, the third-order polynomial die and the cosine die are the best amongst the profiles considered.The mathematic function of die cavity surface is established, and the model for aluminum alloy flat-plate extrusion is constructed. Based on this, the extrusion power and maximum equivalent stress are obtained by using FEM. During this process, some related factors are considered, including die cavity surface length, die calibrating strap length, friction factor, extrusion speed and die cavity surface shape. As a result, the optimal design for aluminum alloy flat extrusion is achieved, and from which the optimum parameters of extrusion process and die design are got.The research results have great signification in improving the extruding die design theory for aluminum alloy.