Electromagnetic forming is a method of high-speed metal workpiece forming technology that uses electromagnetic force pulses generated from the interaction of the magnetic flux density and workpiece induced eddy current. The main challenge of this technology is the control of the eddy current and magnetic flux density to perform various forming processes. This paper is aimed at overcoming this challenge by introducing a new electromagnetic sheet forming method based on discretely driven rings. In this method, a set of discrete conducting rings are placed between the driving coil and the metal workpiece to enhance the shaping process of the workpiece. By changing the number and position of the rings, the induced eddy current can be adjusted, and different electromagnetic force distribution profiles can be realized. COMSOL software is used to develop an electromagnetic field–structure coupling model of the proposed electromagnetic forming method. The characteristics of the electromagnetic force distribution and its effect on the workpiece forming process are analyzed. Results show that the electromagnetic force distribution profile can be controlled by adjusting the rings physical parameters such as diameter, material, and position. The proposed method can effectively improve the performance of the conventional electromagnetic forming technology and has the potential for implementation in wide industry applications.

Electromagnetic forming is a well-developed high-rate forming technology. An important issue of this technology is the temperature rise of the driving coil, which can adversely affect the coil service life. This paper is aimed at addressing this issue through detailed investigation of an electromagnetic forming based on half-wave current method. On the basis of the principle of electromagnetic forming and finite element modelling, this paper compares and analyzes the temperature rise profile of the driving coil along with the forming efficiency of the workpiece in the traditional discharge, the crowbar discharge and the half-wave current discharge models. Results show that with the same system discharge parameters, the half-wave current method can reduce the Joule heating of the driving coil from 1.82kJ to 1.3kJ, which effectively reduces the temperature rise of the driving coil. At the same time, the workpiece forming efficiency is improved from 9.6% to 11.8%. Thus, the half-wave current method can solve the issue of the temperature rise of the driving coil to some extent and promote the process of industrial applications of the electromagnetic forming technology.

Improving the forming efficiency at a reasonable cost has been the main challenge in the electromagnetic forming technology. Towards this aim, this paper proposes a simultaneous cost-effective double-sheet electromagnetic forming method using single driving coil. In order to highlight the features of the proposed technique, comparison of the performance of five electromagnetic forming models is presented. These models include a no-sheet model, single-sheet stationary model, single-sheet moving model, double-sheet stationary model and double-sheet moving model. For each model, electromagnetic force distribution and forming efficiency of the workpiece are analyzed. Furthermore, the influence of the pulse current width of the driving coil on the electromagnetic forming efficiency of the plate is investigated for all models. Results show that for the same system discharge parameters, electromagnetic forming efficiency of double-sheet is 21.14% whereas the single-sheet electromagnetic forming model only achieves 14.68% efficiency. Thus, the double-sheet electromagnetic forming technology can improve the low forming efficiency of a single-sheet electromagnetic forming method and at the same time, the method can form two workpieces simultaneously which makes it more cost effective than the single-sheet method.

Non-uniform axial deformation and tube wall thinning are the main issues restricting the further development of the tube electromagnetic bulging technology. Aiming at overcoming these issues, a tube electromagnetic bulging method based on convex driving coil is proposed in this paper. An electromagneticstructure coupling model of the tube electromagnetic expansion process is established and the influence of detailed convex coil parameters on radial and axial Lorentz forces are analyzed. Results show that with the new proposed method, the homogeneous length of the tube axial deformation is 4.7 times that of the expansion loading with conventional driving coil. Meanwhile, the issue of tube wall thinning in the conventional electromagnetic bulging method is restrained due to the produced axial electromagnetic force using the proposed convex coil. The proposed tube electromagnetic bulging based on convex coil can effectively overcome the issues currently exist in the conventional tube electromagnetic bulging and promote wide industrial application of the electromagnetic forming technology.

Due to the fact that geometrical structure of tube electromagnetic bulging process with field shaper does not conform to the axisymmetric property, three-dimensional (3D) model is usually used to analyze the process which is complicated and time consuming. Therefore, on the basis of understanding the working principle of the field shaper, a two-dimensional (2D) model with current constraint is proposed in this paper to analyze the electromagnetic bulging process of a tube fitted with a field shaper. COMSOL finite element analysis software is used to develop three models for performance analysis and comparison, these are: conventional 3D model and the proposed 2D model with and without current constraint. Simulation results show that the induced eddy current density, magnetic flux density and electromagnetic body density of the two-dimensional model with current constraint are in good agreement with the results of the three-dimensional model. This provides an alternative and effective way to analyze the performance of the tube electromagnetic bulging with field shaper using a simple but yet reliable 2D model.