Investigation of Incremental Tube Forming to Establish a Process Model in Order to Predict Springback

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The importance of lightweight structures is continuously increasing. These lightweight structures are often based on tubular bent parts. Furthermore, these parts often have a cross section that variesalong the longitudinal axis to adopt to the loads during their application. The variation of the cross section can be achieved by modifying the wall thickness or the tube diameter. These tubular bent parts are manufactured in process chains. An alternative is the Incremental Tube Forming process. This process is a combination of a tube bending and a tube spinning process. The superposition of these two processes leads to a reduced bending moment and a reduced springback of the tube. This project focuses on the description and explanation of the mentioned reduction by implementing a process model for Incremental Tube Forming. On the basis of a process model for two-dimensional bending, the process model shall be extended to several process variants. The three-dimensional bending of a tube leads to an additional torsional moment within the tube due to the change of bending planes. This additional bending moment shall be integrated into the process model. Another process variant is the usage of a mandrel which can directly influence the wall thickness during the spinning operation. The changed stress state shall be derived and included into the process model. Finally, a comprehensive process model shall be created which can describe the reduced bending moment and reduced springback for the Incremental Tube Forming process. The theoretical approach is supported and verified by experimental and numerical data.