Transversal compression drawing of structural sheet metal parts by continuous slide in of flange edge
Final Report Abstract
The research project „Transversal compression drawing of structural sheet metal parts by continuous slide in of flange edge” addressed the development of an innovative process concept considering the limitations of conventional approaches to compensate springback effects in sheet metal forming. Compared to conventional deep drawing processes, the developed Transversal Compression Drawing Process is characterized by the substitution of the blank holder by a contoured slider mechanism. This concept enables a horizontal and vertical force transmission onto the blank edges, allowing precise calibration of the flange area at the end of the forming process. This results in a tool-controlled, reproducible, and progressive draw-in of the blank that is only minimally affected by frictional conditions, as opposed to the use of conventional blank holders. The process is also characterized by forming kinematics that enable the continuous superposition of bending and compressive stresses through buckling and rollbending mechanisms, thus achieving a significant reduction in springback. To develop and validate the process, selected advanced high-strength dual-phase (DP) steels were initially characterized and modelled with respect to their properties under cyclic loading conditions. Complementary investigations were conducted to discretize sheet metal blanks using hexaeder elements and required contact formulations. The material models were validated based on experimental investigations of the fundamental forming mechanisms, particularly buckling and roll bending. Based on these findings, a fully parameterized finite element (FE) model was implemented in LS-DYNA. Subsequently, a numerical sensitivity analysis was performed to examine the influence of forming kinematics, as well as process and tool parameters on the Transversal Compression Drawing Process (TCD) in order to identify an efficient forming process of dimensionally accurate sheet metal parts. Based on the obtained findings, an innovative modular tool concept was developed, enabling forming experiments for both TCD and deep drawing. While a conventional blank holder was employed for the deep drawing experiments, roller cams with adaptable driver contours facilitated vertical and horizontal slide movements and thus the desired progressive blank draw-in kinematics during TCD. Geometric and mechanical analysis of the components formed by deep drawing and TCD with this tool showed a significant reduction in springback and sheet thinning as well improved material and process efficiency due to the novel forming method. Finally, the validated FE model was used to transfer the developed forming method to more complex part geometries. This enabled an assessment of the potential of the process to improve dimensional accuracy and efficiency in the series production of structural parts.
Publications
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New sheet metal forming process for springback reduction by continuous stress superposition. IOP Conference Series: Materials Science and Engineering, 1157(1), 012030.
Briesenick, D.; Liewald, M. & Riedmueller, K. R.
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Verfahren und Vorrichtung zum Zugdruckumformen eines Blechs. DE10 2020 105 396.7, 02.09.2021.
D. Briesenick & M. Liewald
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Efficient net shape forming of high-strength sheet metal parts by Transversal Compression Drawing. The International Journal of Advanced Manufacturing Technology, 130(5-6), 3053-3063.
Briesenick, David & Liewald, Mathias
