AsPro – Fundamentals of process design for dimensionally accurate roll forming of asymmetric profile geometries

In the project “Fundamentals of process design for dimensionally accurate roll forming of asymmetric profile geometries”, various asymmetrical hat and U-hat profile geometries are investigated for profile defects and measures for reducing profile defects are derived. With the aid of numerical parameter studies, correlations between process parameters and profile defects are identified and the process parameters optimized. In addition, various strategies for straightening asymmetric profiles are investigated. Due to the high computing times of numerical simulations, an analytical model for the prediction of twists based on given longitudinal strain distributions will also be developed.

Coordinator: Johannes Kilz M. Sc.
Duration: November 2019 – September 2021
Funded by: DFG

Motivation

Roll forming is a continuous process for producing profiles from cold-rolled starting material. Roll forming profiles are mainly used in the transportation and construction industries. Weight reduction plays an important role in increasing the efficiency of means of transport. Due to their stress- and weight-optimized design and efficient production, asymmetrical rolled profiles are particularly suitable for this purpose. However, due to the process, the sheet to be formed undergoes not only the desired transverse bending but also undesirable deformations, which in turn cause profile defects such as horizontal and vertical bow and twisting of the profile. These profile errors are particularly pronounced in asymmetrical profiles. Due to the lack of fundamental knowledge regarding the relationships between longitudinal strains and profile defects in asymmetric profiles, the design of roll forming processes is iterative and thus very inefficient.

Procedure for achieving a defect-free asymmetric hat profile
[1] Procedure for achieving a defect-free asymmetric hat profile

Approach

The aim of this project is to investigate mechanisms that cause profile defects during roll forming of asymmetric profiles. In addition, an analytical model for predicting twists in asymmetric profiles is to be developed and countermeasures derived on the basis of the knowledge gained. Figure 1 shows the basic procedure for achieving an error-free asymmetric hat profile.

To identify the influence of process parameters on profile defects in asymmetric profiles, numerical parameter studies are performed. This is followed by experimental validation of the simulations. Based on the results of the parameter study, the numerical model is extended by different straightening operations in order to identify suitable straightening operations for straightening asymmetric hat profiles. Subsequently, the numerical simulation is coupled with an optimization algorithm to optimize the parameters of the most promising straightening operation.

In addition to the numerical and experimental investigations, an analytical model is developed to predict twisting for given longitudinal strain distributions across the profile cross-section.

Acknowledgement

The presented research project is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 407937637.

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