Kinematic Tool-Bound Profile Bending using Transformer-Tools

• Applicants: Professor Dr.-Ing. Bernd Engel; Professor Dr. Ulf Lorenz
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 509709804

The overall objective of this project is to increase the flexibility of tool-bound profile bending processes to partially kinematic processes trough in-situ adjustment of tool working surfaces, which are generated by active, variable truss-like lattice structures. In addition to the necessary development of sensors, actuators and control systems, mechanistic issues regarding the tool design are to be investigated first. These focus the core of the proposed project, in which the two proposers are working on complementary topics. The first proposer deals with the tool working surfaces aiming for researching methods for the geometric design of segmented surfaces with respect to size and geometry alongside to the arrangement of gaps and shoulders between the segments. For this purpose, the effect of the segmentation on the local deformation behaviour as well as the resulting global deformation behaviour of closed profiles based on the locally acting normal and bending stress, will be investigated in the scope of the project. Each tool segment is understood as a potential actuator, not only allowing a major change of the surface contour, but also the local adjustment of tool-bound and partially kinematic design. Therefore, a further aim is to investigate mechanisms for modifying the shaping tool surfaces as a basis for in-situ adjustment. Based on an analysis of the local acting stresses during rotary draw bending with conventionally closed tool surfaces, finally a method for the generation of bending shapes with segmented tool surfaces is derived, with which a locally and temporally variable bending radius can be produced.The tool structure, which is the research aim of the second proposer, must consequently be able to induce these time- and location-variable segment displacements and simultaneously derive the loads from the forming process. With this overarching goal, new shape and topology optimization methods are being explored to model how to find such a rod structured tool design using mixed integer optimization (MIP). The core of the methodology is to extract model-based solutions from a large number of possibilities, which lead to functional tools in engineering practice, but are near-optimal within the models. Combining the methods developed by both proposers, the outcomes are brought together in the joint work packages. The aim is to develop a design method for bending tools that couples the forming-related boundary conditions with the algorithms for determining the truss-like lattice structure. Concluding, these results will lead to functional models of transformer-tools, which will been used to validate the developed design method and to show possible technical concepts.

• DFG Programme: Research Grants