Transversal compression drawing of structural sheet metal parts by continuous slide in of flange edge

• Applicant: Professor Dr.-Ing. Mathias Liewald
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 453313448

Lightweight structures allow current and future ecological and economic requirements to be met, especially in the automotive industry. In this context, use of formed structural components made of high-strength and ultra-high-strength sheet steel offers numerous cost and weight saving potentials with regard to manufacturing and application.However, during forming of sheet metal materials, especially of high-strength and ultra-high-strength steel sheets, various springback phenomena occur which negatively affect the dimensional accuracy of the components and the robustness of the manufacturing processes. These springback effects are mainly dependent on the properties of the materials to be formed, the process conditions and the component geometries to be produced. Therefore, many springback compensation methods are endeavored to reduce springback by geometrical or process modification. Here, possible measures here are hot forming, multi-stage cold forming with stress superposition or deep drawing with variable blankholder forces. However, such compensation measures become more difficult due to the ever-increasing strength of the semi-finished products to be formed, which leads to increased tooling costs or to the power supply of existing press technology being exceeded. Proposed research project addresses process development of a new forming method for the production of structural sheet metal parts made of high-strength steels. “Transversal Compression Drawing” is an approach to form hat-shaped parts with reduced springback and load by an additional continuous induced horizontal force on flange area. Minor deep drawing tool modifications result in a superimposed bending by buckling and rolling with additional compressive stresses. Numerical studies already revealed reduced springback, process loads and blank sizes and indicated the feasibility of the new forming method on simple and complex structural parts. Main objective of proposed investigation consists in verifying application and practicability of “Transversal Compression Drawing” using experimental and numerical methods. Starting with an experimental characterization of dual-phase steel materials and basic studies on bending by buckling and rolling, numerical studies on validated simulation model reveal sensitivities between controlled transversal flange movements, bending behavior of sheet metal, stress states before and after springback and resulting shape deviations. The development of a tool concept with an implementation of new requirements such as the controlled transversal application of forces in the flange area allows experimental studies and a validation of numerical results. Finally, the numerical process design of representative structural parts demonstrate feasibility and transferability of the new forming method for further research and practical applications.

• DFG Programme: Research Grants