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Härte und Funktionalität erzielen Lebensdauersteigerung

Hardness and functionality achieve lifetime increase

© IFW/Nm
Deep rolling of a bearing inner ring

How must the edge zone of hardened components be designed to resist strong loads and how can this be achieved with the manufacturing process? Researchers at the Institute of Production Engineering and Machine Tools at the Leibniz Universität Hannover (IFW) are addressing these questions. They are investigating how combined processes can be used to specifically exploit special thermal and mechanical effects. "The aim is to adjust the edge zone of hardened components so that they can fulfill their function for as long as possible," explains project manager Henke Nordmeyer.

Hardened components are often used where high loads are expected. Hardened components can withstand these loads for a long time. The acting load conditions are frequently changing and lead over time to the formation of cracks and later even to fracture of the component. "This failure of the components can be counteracted by a load-adapted edge zone," says Henke Nordmeyer. This means that the properties of the edge zone are adjusted so that the loads can be absorbed during use of the component without causing damage to the component. In the basic research project "Functionalized edge zone for load-oriented fatigue behavior of hardened components," the relationships between manufacturing processes and component service life are being investigated.

In the newly launched DFG project, components subjected to bending fatigue are being examined as well as bearing rings subjected to rolling loads in cooperation with the Institute of Machine Design and Tribology (IMKT). The specific adjustment of the component edge zone with the combination process of deep rolling is first investigated by analyzing the interactions of the individual processes. For this purpose, a local induction heating is connected upstream of the deep rolling in order to be able to map the temperature input by the turning process. This analog heat source allows the process temperatures to be varied in a targeted manner and thus optimum process conditions to be designed for the load-adapted production of the hardened components. The turning process is then investigated to determine the process window that provides the necessary heating for rolling The model developed from this is used to derive boundary zone conditions for the components subjected to bending fatigue and rolling loads. The components manufactured using the model are then subjected to service life testing to determine the extent to which a defined set of edge zone conditions increases service life as a result of the rolling process.

Contact

For further information, please contact M. Sc. Henke Nordmeyer, Institute of Production Engineering and Machine Tools by e-mail at nordmeyer@ifw.uni-hannover.de or by phone at +49 511 762 18295.