Profile Forming with Stress Superposition

• Applicant: Professor Dr.-Ing. A. Erman Tekkaya
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 509859510

For increasing the component performance and stabilizing the process control, in some sheet metal and profile forming processes additional stresses are deliberately superimposed on the effective stress. In this project, the stress superposition in incremental profile forming for the production of profiles with variable cross sections along the longitudinal axis is to be analyzed. During this process, a round tube is formed into a complex shaped profile by pushing in forming elements from the side and axial slide drawing. In contrast to hydroforming, the incremental method allows different geometries to be produced with a single tool set. At present, however, investigations into incremental profile forming have not yet produced satisfactory results for the user in terms of relevant process and component properties such as dimensional accuracy. Due to the increasing demand for the processing of ever higher-strength materials, the increasing springback potential of the materials must also be expected to continue. The focus of the project is to describe the stress and deformation states that form in different types of stress superposition. Based on the stress and strain states, the setting of the deformation capacity as well as component properties such as residual stresses, hardness or surface quality are to be described. In order to determine the stress and strain states as a function of the type of stress superposition, the individual superposition methods are considered in isolation. Axial tension, axial compression, radial compression and torsion are taken into account as superposition methods. By investigating both kinematic and shape-related forming methods, different deformation states are to be generated in order to be able to describe the influence of a stress superposition during profile forming in a generally valid manner, and thus independently of the deformation state. Similarly, the two basic process kinematics of radial indentation and axial drawing are to be analyzed. Numerical analysis is to be used to describe the deformation changes and stresses in the component. An analytical model is to be derived to describe the forming forces and the stresses and strains at characteristic points such as the center of the groove. In order to use the model to physically represent the influence of the type of stress superposition, the model is to depict the resulting strain starting from physically calculable strain states in basic forming mechanisms such as bending and stretching.For the experimental validation of the numerical simulations and the analytics, an existing machine for incremental profile forming will be extended in the project to such an extent that different types of stress superposition can be considered.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr.-Ing. Till Clausmeyer; Dr.-Ing. Heinrich Traphöner