Incremental Sheet-Bulk Metal Forming by Application of Thermally-Controlled Grading Mechanisms

The subject of the transfer project was the extension of incremental sheet bulk metal forming (iSBMF) for hot sheet forming. The aim was to locally influence the flow stress by local heating (Figure a). An analytical approach was used to demonstrate the feasibility of this technology. This provided the required temperature profile for the local reduction of the flow stress (Figure b). In this way, homogenization of the material flow can be achieved. During the project, in particular heating proved to be challenging. Approaches for conductive, inductive, combined heating, and cryogenic cooling as well as laser heating are at the limit of what is technically possible. The required temperature gradient of ΔT = 850 °C over a width of 5 mm is currently not achievable due to the thermal conductivity of the material (Figures c-d). The successful collaboration was carried out with the industrial partners Winkelmann Powertrain Components, thyssenkrupp Hohenlimburg, Faurecia Autositze, and voestalpine High Performance Metals Deutschland.