P 1058 – Lightweight design through targeted generation of local part properties with optimized forging and machining processes
As part of the research network “lightweight forging”, the Sub-project 4 “Extending
technological boundaries by forming in different temperature ranges” investigated three demonstrator parts that were manufactured through fundamentally different processes of bulk metal forming in diverse temperature ranges. The content of the first work package consisted of the investigation of manufacturability of a piston pin by Ironing and the optimization of a spiral inner contour of in terms of its lightweight potential compared to a conventional cylindrical inner contour. In the second work package of the subproject, the focus was on the production of a gear shaft, also by a process of cold bulk forming, namely forward rod extrusion. The aim here was to optimize the surface properties hardness, roughness and residual stresses with regard to a possible downsizing or the saving of subsequent heat treatments. With the aim of a possible substitution of conventional hardening processes, extruded components were deep-rolled on the basis of optimized parameter sets. It could be shown that the properties of heat treated components can be further improved by means of deep rolling. However, deep rolling of cold-formed components leads to a surface failure in the form of cracks and flaking. In the field of hot bulk forming, multistage precision forging could be successfully used to adjust local microstructural properties. On a gear rim, a fine-grained microstructure with a typically good strength to toughness ratio was set by selective thermo-mechanical treatment during the production of parts. Based on the demonstrator components examined, the generated results show that the processes of bulk forming possess many hidden potentials in terms of manufacturing lightweight components, which is becoming more and more important.
Not only was it possible to show that the processes of bulk forming in all temperature ranges allow the generation of ever new component shapes with increasingly efficient production sequences, but also that a targeted adjustment of local component properties is generally possible. In order to achieve this, the means of numerical process simulation must be exploited and further developed and conventional forming processes must be rethought from scratch. Although these points always come with new challenges, they can, as the results of the sub-project show, be managed within the framework of collaborative research projects such as the “lightweightFORGING” Research Network.
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FOSTA – Research Association for Steel Application