An analytical model on twisting deformation of rod extrusion through conical die with rotating container

• Friction distributions were changed by extrusion through rotating container.
• Load of extrusion through rotating container decreased.
• Twisting length expressions and extrusion load were obtained.
• Deformation degree of the billet improved.

Reducing energy consumption and improving material properties of the extrusion processing are important problems to be solved. The application of torque on the container can transform the friction distribution on the outside surface of billet during the extrusion, and a component of friction force need to be overcame. Due to the large contact area between container and billet, the effect and significance of this method for load reducing appears. In this paper, on the basis of a reasonable assumption to velocity field in the process of rotating container, the twisting length of the billet inside the stationary container was derived by the use of the upper-bound method. The comparison result indicates, when the rotating speed of container lies in a specific range (0–1 rad/s), the average extrusion pressure applied by the punch decreases apparently with the friction increasing. Unlike the traditional extrusion which usually decreases the friction factor in order to improve the properties of the material. Although the relative slippage inevitably occurred between the billet and the container, the optimum results could be obtained by optimization of the slippage parameters.