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

轻量化结构的重要性不断提高。这些轻质结构通常是基于管状弯曲部件。此外，这些零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。可以通过改变壁厚或管径来实现截面的变化。这些管状弯曲零件是在流程链中制造的。另一种方法是增量式管成形工艺。该工艺是弯管和旋管工艺的结合。这两个过程的叠加导致了弯矩和回弹的减小。本项目的重点是通过实施增量管成形工艺模型来描述和解释上述减量。在二维弯曲工艺模型的基础上，将工艺模型扩展到几种工艺变量。由于弯曲面的变化，管子的三维弯曲会在管子内部产生额外的扭矩。该附加弯矩应整合到工艺模型中。另一种工艺变化是使用芯棒，它可以在旋压操作期间直接影响壁厚。应推导出更改后的应力状态，并将其包含在工艺模型中。最后，建立了描述管件渐进成形过程中弯矩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.