Newest Developments on the Manufacture of Helical Profiles by Hot Extrusion

A new innovative direct extrusion process, helical profile extrusion (HPE) is presented, which increases the flexibility of aluminum profile manufacturing processes. The application fields of such profiles can be seen in screw rotors for compressors and pumps. The investigations concentrate on experimental and numerical analyses by 3D-FEM simulations to analyze the influence of friction and the material flow on the twisting angle and contour accuracy. By means of finite-element method (FEM), the profile shape could be improved by modifying the die design. The numerical results were validated by experiments. For these investigations, a common aluminum alloy AA6060 was used. Mainly, the friction in the die influences the twist angle and the shape of the helical profile. Two die coatings were analyzed, but the friction was not substantially decreased in any of these cases. Although there is no efficient practical solution for reducing the friction in extrusion dies using tested die coatings, the required profile contour could be achieved by new die designing and by modifying the material flow. However, increasing the twist angle is limited due to geometrical aspects of this technology, namely, by the ratio of the volume to the contact area with the die for the displaced metal.