Residual stress-controlled incremental sheet forming of high-strength sheet metal components

增量式钣金成形（ISF）工艺适用于按特定要求经济地制造小批量零件。构件的性能特别取决于构件中的残余应力。该研究项目旨在通过成形残余应力改善高强度钢构件的性能。在以前的资助期间，通过成形过程以特定方式影响残余应力的潜力已得到证实。结果表明，ISF的工艺参数直接影响弯曲、剪切和法向应力分量的变形机制，从而影响残余应力状态。在第二个资助期，分析了通过形成诱导残余应力来改善构件性能的可行性。工艺增强可以诱导更高的残余应力或压缩残余应力到拉伸残余应力的反转。第三个资助期的重点是预测构件性能改善和腐蚀环境下连续运行的残余应力稳定性。在与Faurecia Autositze GmbH的一个转移项目中，这些发现根据工业要求进行了转移。为此，先前分析的材料扩展到高强度双相钢和工业用途的面向应用的几何形状。除了静力和循环载荷作用下的构件性能外，还分析了对制造构件几何精度的影响。采用摆动刀具运动的概念来引入额外的近表面压缩残余应力，并减小加工力。应通过同时使用多种成形工具来减少加工时间。

The incremental sheet metal forming (ISF) process is suitable to economically manufacture components in small batch sizes according to specific requirements. The component properties are particularly determined by the residual stresses in the component. The aim of the research project is to improve the component properties made of high-strength steel through forming-induced residual stresses. The potential of influencing the residual stresses in a specific way through the forming process was proven in the previous funding periods. It was shown that the process parameters of ISF directly influence the deformation mechanisms bending, shearing and normal stress component, which effects the residual stress state. In the second funding period the achievable improvement of the component properties by forming induced residual stresses was analyzed. Process enhancements enable an induction of higher residual stresses or an inversion of compressive to tensile residual stresses. The third funding period focused on the prediction of the component property improvements and the residual stress stability under continuous operation in a corrosive environment. In a transfer project with Faurecia Autositze GmbH these findings are transferred under industrial requirements. For this purpose, the previously analyzed materials are extended to high-strength dual-phase steels and application-oriented geometries for an industrial use. In addition to the component performance under static and cyclic loads, the influence on the geometrical accuracy of the manufactured components is analyzed. A concept with an oscillating tool movement is applied to introduce additional near-to-surface compressive residual stresses close and reduce the process forces. A reduction of process time should be achieved by the simultaneous use of multiple forming tools.