with optimized forging and machining processes (P 1057 / Pre-Competitive Cooperative Industrial Research Project (IGF) No. 18225 N) IFU, IUL, ISF

Subproject 3 of the “massiverLEICHTBAU” (Lightweight Forging) joint project, funded by the German Federation of Industrial Research Associations (Arbeitsgemeinschaft industrieller Forschungsvereinigungen – AiF) and the Federal Ministry for Economic Affairs and Energy (Bundesministerium für Wirtschaft und Energie – BMWi), is being worked on as collaborative research program under the management of the Institute for Metal Forming Technology (Institut für Umformtechnik – IFU) of the University of Stuttgart. The cooperating institutes are as follows: the Institute of Forming Technology and Lightweight Construction (Institut für Umformtechnik und Leichtbau – IUL) as well as the Institute of Machining Technology (Institut für Spanende Fertigung – ISF) at the Technical University of Dortmund. In the subproject, lightweight design potential is being analysed through the targeted generation of local part properties with optimized forging and machining processes. A method for efficient CAE-based design of optimized and robust cold extrusion and downstream machining processes are being developed for cost-efficient manufacture of lightweight design components.

The cold extrusion of steel parts leads to an improvement in mechanical material properties as a result of strain hardening. Due to this increase in strength, lighter parts can be designed. Usually it is assumed that only a global increase in material strength can be achieved reliably with forging and that lightweight design potential may be gleaned from this. The local strength properties of cold forged workpieces as well as residual stresses and in particular fibre flow are currently often not taken into account sufficiently when designing the part, the forging process and the subsequent machining processes. Similar deficits exist in the development of steel materials.

It is the goal of this subproject to bridge the gap between the requirement definition of local part properties, particularly with respect to strain hardening, residual stresses and load-adapted fibre flow, and ensuring these properties through optimized forging and machining processes as well as through the development of steel materials with process-adapted properties (cold forgeability, flow stress, strain hardening, machinability). Furthermore, an efficient method for the virtual design of robust forging and machining processes should be developed, taking into account optimum local part properties.

Following the process chain, FEM forging simulations will be used to model local part properties initially during cold extrusion (IUL) and then during subsequent machining (ISF). In a structural/mechanical FEM simulation, the preceding results will be recorded and part properties dependent on the stress direction will be determined (IFU). The results of these three simulation packages will then be used for incorporating into a CAE-based design of optimized and robust process chains. To verify the lightweight design potential, this method will be used to develop two demonstration parts, namely a gear hub and a piston pin (IFU). For the gear hub, a tool will be set up and a joined gear produced based on SP2 (IFU). With the results achieved, economic feasibility studies will subsequently be carried out with respect to machining (ISF) and technological part tests conducted to determine the lightweight design potential and costs (IFU).