A9

Working Group A | Metallurgical joint

 
 
a9_spp1640

Studies on the reproducibility of the Magnetic Pulse Welding in the case of an asymmetric impact

Prof. Dr.-Ing. Prof. h.c. Stefan Böhm, Universität Kassel

 
 

Abstract:

The main objective of the project is to increase the reproducibility of the MPW. The influence of surface pre-treatment on the reproducibility and on 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 that are 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 lower welding curve has to be supplemented with a factor for the surface.

 
 
Schematic diagram of asymmetric impact
Schematic diagram of asymmetric impact

Increasing the reproducibility by:

  • measuring of collision speed and collision angle for the shock pressure
  • formation of the lower curve of the weld area
  • influence of the grain size and surface pre-treatment
  • verification of the results in collaboration with project A5 (PtU) and project A8 (IWW)
 
 

In the proposed project, the roughness and its orientation with respect to the welding direction are specifically considered as a surface effect. More surface influences than those 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 both be achieved by simulating results of the project A5 and by using an experimental setup with aPlexiglas target and a high-speed PSD sensor. The application of different pre-treatments showed that a smoother target surface leads to an early beginning of the welding zone and a rough surface leads to a wide welding zone. For the explanation of this effect, the hypothesis is that a “thin” jet – which is produced through a small collision angle – is sufficient to initiate the welding process at the beginning of the weld. This requires a clean surface. At the end of the welding process, when the collision angle is so large that the welding window is left at the top, a perpendicular roughness reduces the collision angle locally and the welding process is prolonged. Thus, a further aim of the project is to increase the roughness of the surface by a gradient so, that the welding process starts with a smooth surface and ends with rough surface. The welds will be more reproducible and the weld length will be constantly high. To achieve these objectives, a close cooperation is planned with both the A5 project from Darmstadt (PtU) as well as with the project A8 from Chemnitz (IWW).

 
 
Recording of the asymmetric impact with a high speed camera at the department tff (High Speed PSD Sensor, MICROEPSILON)
Recording of the asymmetric impact with a high speed camera at the department tff (High Speed PSD Sensor, MICROEPSILON)
 
 

Publications:

2019   
  Investigation of the Temperature Influence of the Static Joining Partner on the Lower Welding Limit during Magnetic Pulse Welding Schumacher, E.; Prints, E.; Graß, M.; Böhm, S.
In: 22nd International Conference on Material Forming 2019, 08.05.2019-10.05.2019, Vitoria-Gasteiz, 2019
  Influence of the jet velocity on the weld quality of magnetic pulse welded dissimilar sheet joints of aluminum and steel Schumacher, E.; Rebensdorf, A.; Böhm, S.
In: Materials Science and Engineering Technology – Special Issue SPP1640, Submitted on 27.02.2019, 2019
  On the microstructure and the origin of intermetallic phase seams in magnetic pulse welding of aluminum and steel Böhme, M.; Sharafiev, S.; Schumacher, E.; Böhm, S.; Wagner, M. F.-X.
In: Materials Science and Engineering Technology – Special Issue SPP1640, Accepted on 27.02.2019, 2019
2018   
  Influence of the Ambient Pressure on the Weld Quality for Magnetic Pulse Welded Sheet Joints Kümper, S.; Schumacher, E.; Böhm, S.
In: 8th International Conference on High Speed Forming 2018, 14.05.2018-16.05.2018, Columbus (OH), 2018
  Analysis of the Weld Seam Area of Magnetic Pulse Welded Aluminum-Steel-Sheet-Connections on its Suitability as a Sign of Quality Schumacher, E.; Kümper, S.; Kryukov, I.; Böhm, S.
In: 8th International Conference on High Speed Forming 2018, 14.05.2018-16.05.2018, Columbus (OH), 2018
2016   
  Increase of the Reproducibility of Joints Welded with Magnetic Pulse Technology Using Graded Surface Topographies Rebensdorf, A; Böhm S.
In: 7th International Conference on High Speed Forming 2016, 27.04.2016-28.04.2016, Dortmund, 2016
2015   
  Influence of the Collision Speed and Collision Angle in Magnetic Pulse Sheet Welds Rebensdorf, A.; Böhm, S.
In: International Impulse Forming Group-Impulse Forming Workshop 2015, 05.10.2015-06.10.2015, Dortmund, 2015
 

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