Development and manufacturing of optimized working coil windings for electromagnetic forming employing additive manufacturing techniques

电磁成形工艺(EMF)使用磁力来成形导电金属薄板和型材。电动势的主要优点是非接触力传递和高应变率。然而，电动势的使用受到限制，因为工作工具的耐用性较低，而且生产的设计指南有限。此外，目前应用的工作线圈生产方法极大地限制了工具适应各自成形任务的可能性。在该合作研究项目的第一个资助期内，铜合金CuCr1Zr获得了选择性激光熔化(SLM)的资格。用于实际电动势研究的工作线圈是通过SLM制造的。使用附加工作线圈的电动势实验表明，成形结果与由变形铜合金制成的工作线圈相当。首次对混合工作线圈的生产和使用进行的研究也表明，与单片工作线圈相比，通过在钢衬底上添加一层薄铜层，可以提高工艺效率。此外，还对电动势过程中作用在工作线圈上的热机械载荷进行了研究，为设计指南的制定提供了支持。单片和混合线圈概念的附加制造也是第二个资助期的重点。设计和制造复杂的单片多圈工作线圈是这些研究的目标之一。这就要求开发用于电磁场过程和工具设计的SLM扫描战略和仪器。由于附加制造的工作工具的后处理或工作线圈之间的额外相互作用等限制，需要进行无法在第一个供资期间完成的进一步调查。混合线圈概念的发展旨在实现电磁成形操作，这是使用单片概念无法实现的。复杂的材料相变是SLM研究的重点。成形工艺和工装设计的目的是实现电流传递和机械支撑功能的分离。这种方法实现了导电铜层局部电流集中和抑制塑性变形的新概念。

The electromagnetic forming process (EMF) uses magnetic forces for forming of electrically conductive metal sheets and profiles. The main advantages of EMF are the non-contact force transmission as well the high strain rates. However, use of EMF is restricted because of low durability of the working tools and limited availability of design guidelines for their production. Additionally, the currently applied production methods for working coils considerably limit the possibilities for adapting tools to the respective forming task.During the first funding period of this collaborative research project the copper alloy CuCr1Zr was qualified for Selective Laser Melting (SLM). Working coils for practical EMF investigations were produced via SLM. EMF experiments using additive working coils have shown forming results which are comparable to working coils made of a wrought copper alloy. First investigations focusing on the production and use of hybrid working coils have also shown that by additive application of a thin copper layer to a steel substrate, the process efficiency can be increased compared to monolithic working coils. Additionally, the thermomechanical loads acting on the working coils during the EMF process were investigated, which support the development of design guidelines. Additive manufacturing of monolithic and hybrid coil concepts is also the focus of the second funding period. Design and manufacturing of complex monolithic multi-turn working coils is one of the goals of these investigations. This requires the development of SLM scanning strategies and instruments for EMF process and tool design. Because of restrictions e.g. by post-processing of additively manufactured working tools or additional interactions between the turns of working coils there is demand for further investigations, that could not be completed in the first funding period. The development of hybrid coil concepts aims to realize electromagnetic forming operations, which are not possible using monolithic concepts. The complex material transitions are the focus of SLM investigations. The process and tool design for the forming process aims at a separation of the functions conduction of current and mechanical support. This way new concepts for a local current concentration and a suppressed plastic deformation of the conductive copper layer are realized.