Joining by die-less hydroforming of profiles with non-rotationally-symmetric cross section

• Applicant: Professor Dr.-Ing. A. Erman Tekkaya
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing ; Production Automation and Assembly Technology
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 256223906

For reason of weight reduction and increased functionality parts and components in modern lightweight constructions are composed of different materials. The high diversity in the properties of the combined materials makes high demands on the joining technology. Conventional and widely used joining processes reach their technological limits or are no longer competitive in terms of economic aspects.Joining by die-less hydroforming is a joining by forming process. It is an alternative to conventional thermal, mechanical or adhesive joining processes and can be used for interference fit and/or form fit joints. Because of its high process reliability and easy process monitoring it is well suited for automated manufacturing processes. To make use of these potentials the proposed research projects aims on an expansion of the current process limits. This means that the current limitation on rotationally symmetric joining partners should lifted so that also joining partners with polygonal or elliptical cross section can be joined successfully. Achievement of this objective requires the- development of joining tools for non-rotationally symmetric cross sections and- approaches for joint and process design.A first prototype tool for profiles with rectangular cross section has already been developed and applied for patent by the Institute of Forming Technology and Lightweight Construction. This concept should be developed further within this research project by experimental and numerical investigations. Increase of the maximum allowable dimensional deviations of the inner joining partner is one of the major objectives in the field of tool construction. In the subsequent step the stress and strain distribution in the joining partners will be determined and correlated with the connection strength. Based on these information guidelines and approaches for joint and process design will be derived.Finally the project provides a flexible joining by forming process suitable for interference and/or form fit joints of profiles with non-symmetrical cross section made of different metallic materials.

• DFG Programme: Research Grants