Bridge tool for the production of extruded profiles with varying cross-sections

The extrusion forming process enables high degrees of forming to be achieved in a single process step and an almost unlimited variety of possible profile cross-sections to be produced. It is an essential manufacturing process, especially for the lightweight material aluminium. In conventional extrusion, however, only rigid forming tools are used, which always form profile cross-sections constantly over the length of a profile. Since the design of components and parts is carried out according to the highest expected stress, but this does not occur uniformly over their length in real technical use, locally oversized profile areas inevitably result in the conventional process.

With the process and tool developed at the TU Berlin, oversized profile sections can now be reduced. This is achieved by integrating movable segments in the tool, which can be moved during the forming process by an externally mounted drive mechanism. By moving the segments vertically to the direction of extrusion, the shaping gap in the tool and consequently the local wall thickness of the hollow section is either reduced or increased. The maximum wall thickness change achievable so far was 1.2 mm. With an initial wall thickness of 4.5mm, this was reduced to 3.3mm, which corresponds to a reduction of approx. 27%. This innovative technology achieves savings in the use of materials and the weight of profiles. These savings reduce fuel consumption and exhaust emissions, especially in weight-sensitive applications such as transportation.