Electromagnetic Force Distribution and Wall Thickness Reduction of Three-Coil Electromagnetic Tube Bulging With Axial Compression

In the conventional electromagnetic tube expansion, tube wall thickness tends to decrease significantly while the workpiece is expanded. This paper is aimed at introducing a new technique using three-coil electromagnetic tube bulging with axial compression as an innovative solution for this issue. To validate the feasibility of the proposed technique and investigate the electromagnetic force distribution along the workpiece, COMSOL software is used to construct a detailed finite element analysis model for the proposed electromagnetic coupling model. Results show that the ratio of the axial and the radial electromagnetic forces increases linearly with the increase of the height and the outer diameter of the top and bottom coils. Furthermore, the tube deformation profile and the wall thickness are compared with two different coil structures. Comparison analysis reveals that for the same axial to radial electromagnetic forces ratio, the effect of prohibiting the wall thickness reduction using different coil structures is quite similar. The new method is expected to have a good potential in enhancing the tube-forming performance.