Study on electromagnetic force distribution and axial uniformity of tube electromagnetic bulging

In the tube electromagnetic bulging, physical parameters of the driving coil are very important to the results of the electromagnetic forming, the height and outer diameter of the driving coil are the main geometric parameters that affect the distribution of the electromagnetic force and the axial tube uniformity. As such, this paper explores the influence of these two parameters on the workpiece relative uniform deformation under electromagnetic forming process from the aspects of magnetic force line characteristics, radial electromagnetic force distribution, and axial relative length. Results show that the changes of the height and outer diameter of the forming coil can modify the characteristics of the magnetic force lines and the electromagnetic force distribution at the end of the tube. Compared with the short and coarse driving coils, the proportion of uniform deformation on the bulging axis of the tube with slender coil is increased by nearly 42%. Obviously, electromagnetic bulging based on driving coil can reduce the uneven distribution of electromagnetic force caused by the end effect of driving coil and lead to uneven axial deformation to a certain extent. Results reveal that the tube electromagnetic bulging based on slender driving coil is easy to achieve axial uniform deformation, this study provides a valuable reference for the uniform of the workpiece in tube electromagnetic forming.