Investigation of Forming Strategies to Set up Mechanical Properties of Parts Made by Incremental Sheet Bulk Rolling

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Load‐adapted parts with an increasing number of functions become more and more interesting in order to reduce the weight of all kinds of mechanical constructions. Such parts require varying mechanical properties and towards they are cost‐expensive. One approach to reduce the costs is the application of cheap semi‐finished parts. To process such parts, especially in thickness direction, bulk‐forming operations are requested. This leads to high forming forces. A feasible approach to reduce the forces is the application of incremental forming techniques. In this paper an incremental rolling process is presented. The sequential order of forming operations during incremental rolling allows an individual adjustment of mechanical and the geometrical properties. In the presented study a sheet with a thickness of 2 mm made of mild steel is formed using a roller ball with a diameter of 13 mm. Main objective of the investigation is to manufacture parts with equal values for thickness but different values of the local surface hardness. The investigation is supported by Finite‐Element‐Analysis (FEA) to determine the distribution of the strains over the part’s thickness. The results show that it is possible to manufacture parts with the same thickness and different surface hardness by applying different forming strategies. Keeping the entire process parameters constant but rolling the part alternating at both surfaces will result in a higher hardness on the surface in comparison to a one‐sided rolling.