Studies on the reproducibility of the magnetic pulse welding in the case of an asymmetric impact

该项目的主要目标是提高MPW的可重复性。从目前的技术水平和我们自己的初步工作来看，表面预处理对再现性和焊缝区域下曲线形成的影响是显而易见的。实验表明，垂直于焊缝方向的干涉轮廓对焊缝的影响较大。为了可重复地使用MPW， MPW焊接窗口的下曲线必须是可预测的。为此，必须将表面纳入下焊接曲线的计算中。焊接下曲线必须加上一个表面因子。在提出的方案中，特别是粗糙度及其相对于焊接方向的方向被认为是表面效应。spp1640项目A5（达姆施塔特）中研究的更多地表影响也应予以考虑和综合。冲击压力所需的碰撞速度将在一侧使用A5项目的模拟结果，另一侧使用有机玻璃靶和高速PSD传感器的实验设置。由于不同的预处理，可以看出光滑的目标表面引导到焊接区域的早期开始，粗糙的表面引导到较宽的焊接区域。对于这种效应的解释，工作假设是“薄”射流足以在小碰撞角产生的焊缝开始时产生更光滑的表面，以清洁光滑的表面并启动焊接过程。在焊接过程结束时，当碰撞角过大而留下以上的焊接窗口时，垂直粗糙度局部减小了碰撞角，延长了焊接过程。因此，该项目的另一个目标是通过梯度增加表面的粗糙度，以便焊接过程从光滑的表面开始，在粗糙的表面结束。焊缝的可重复性更强，焊缝长度恒定。为了实现这一目标，计划与达姆施塔特（PTU）的A5项目以及开姆尼茨（IWW）的A8项目密切合作。

The main objective of the project is to increase the reproducibility of the MPW. The influence of surface pretreatment on the reproducibility and to the formation of the lower curve of the weld area is clear from the state of the art and our own preliminary work. Our experiments show the strong influence of interfering contours perpendicular to the weld direction.To use MPW reproducibly, the lower curve of the welding window for MPW must be predictable. For this purpose, the surface must be incorporated into the calculation of the lower welding curve. The welding lower curve has to be supplemented with a factor for the surface. In the proposed project, especially the roughness and its orientation with respect to the welding direction are considered as a surface effect. More surface influences that are investigated in the SPP 1640 project A5 (Darmstadt), should also be considered and integrated. The collision speed required for the shock pressure will be used at the one side from the simulation results of the project A5 and at the other side from the experimental setup with the Plexiglas target and the high-speed PSD sensor.Due to the different pre-treatments it could be shown that a smoother target surface guides to an early beginning of the welding zone and a rough surface guides to a wide welding zone.For the explanation of this effect, the working hypothesis is that "thin" jet is sufficiently a smoother surface at the beginning of the weld produced during the small collision angle , to clean a smooth surface and to initiate the welding process. At the end of the welding process when the collision angle is so large that the welding window is left after above, a perpendicular roughness reduce the collision angle locally and the welding process is prolonged.Thus, a further aim of the project is increase the roughness of the surface by a gradient so, that the welding process starts with a smooth surface and ends at a rough surface. The welds will be more reproducible and the weld length will be constant high.To achieve the objectives, a close cooperation is planned with both the A5 project from Darmstadt ( PTU) as well as with the project A8 from Chemnitz ( IWW) .