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

轻量化结构的重要性在不断提高。这些轻量级结构通常基于管状弯曲部件。此外，这些部件通常具有沿纵轴变化的横截面，以适应其应用过程中的载荷。横截面的变化可以通过改变壁厚或管径来实现。这些管状弯曲部件是在工艺链中制造的。另一种选择是增量管成形工艺。这个过程是管弯曲和管旋转过程的结合。这两个过程的叠加导致了弯管弯矩的减小和回弹的减小。本项目着重于通过实现增量管成形的过程模型来描述和解释上述减少。在二维弯曲工艺模型的基础上，将该工艺模型扩展到多个工艺变体。管的三维弯曲由于弯曲平面的改变而在管内产生额外的扭转力矩。这个额外的弯矩应集成到过程模型中。另一种工艺变化是使用芯棒，芯棒可以直接影响纺丝过程中的壁厚。应导出应力状态的变化，并将其纳入过程模型。最后，建立能够描述增量管成形过程中弯矩减小和回弹减小的综合工艺模型。理论方法得到了实验和数值数据的支持和验证。

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.