Electromagnetic Force Distribution and Forming Performance in Electromagnetic Tube Expansion with Axial Compression

Electromagnetic tube expansion has been given much attention due to its superior cold forming properties. The traditional electromagnetic coil is of single structure, which results in substantial tube wall thinning and mechanical strength reduction. This shortcoming restricts further development of the electromagnetic tube expansion technology in various industrial applications. This paper proposes an axial-radial electromagnetic force bidirectional loading method to increase the axial fluidity of the material and eliminate the wall thinning issue that currently exists in the traditional method. Furthermore, the performances of three proposed structures for the axial compression electromagnetic tube expansion using three-coil, two-coil and one-coil are analyzed and compared. In this context, the electromagnetic force distribution and the wall thinning of the tube during the expansion process are analyzed based on finite element modelling. Results show that with the proposed modified structure of the traditional single coil, the axial electromagnetic force can be substantially increased which results in reducing the tube wall thinning significantly. The proposed technique in this paper paves the way for further development and more industrial applications of the electromagnetic expansion technology.