Freiformbiegen von rechteckigen Hohlprofilen

This scientific dissertation deals with the freeform bending of rectangular steel profiles using a moving die. The process offers a wide range of design possibilities, but requires a profound understanding in order to optimally utilise its degrees of freedom. The research in this thesis focuses on the transfer of methods from different areas within the field of bending technology, numerical modelling and the extension of the process window, especially by reducing wrinkling in rectangular profiles. The work aims to develop new methods and models that enable an efficient development and realisation process for freeform bent components made from rectangular profiles and can also be transferred to other cross-sections. A rectangular profile made of the fine-grained structural steel S460MC is used for the investigations to develop these methods and models. The anisotropic bending behaviour is analysed, taking into account the weld seam, profile production, material properties and standard tolerances. A developed procedural model enables the determination of direction-dependent process windows and their limits. A distinction is introduced between the hard limits due to boundary conditions and the user-specific soft limits. To measure the elastic tool behaviour during the bending process, a possibility using a laser sensor is presented. This serves as the basis for the creation of a new compensation model for the elastic tool behaviour in the numerical model without having to abandon the rigid body modelling of the tools. The validation of the developed models and methods is carried out using a demonstrator part with a different cross-section and material in order to show the transferability of the developed models. The formation of wrinkles on the profile was identified as the main process limitation. A newly developed die concept is able to influence the formation of wrinkles and enable the process window to be extended by moving a hard limit. Based on this, a small series of the demonstrator component is produced, which is used to investigate the geometric accuracy and process stability. The work presents new methods and models for process design as well as new approaches for process optimisation. The extension of the process window by modifying the die geometry lays an important foundation for future research work and industrial applications. Finally, possible further aspects for future research are presented.     «

This scientific dissertation deals with the freeform bending of rectangular steel profiles using a moving die. The process offers a wide range of design possibilities, but requires a profound understanding in order to optimally utilise its degrees of freedom. The research in this thesis focuses on the transfer of methods from different areas within the field of bending technology, numerical modelling and the extension of the process window, especially by reducing wrinkling in rectangular pr...     »