Abstract
In this paper, we describe the electromagnetic bulging of a SUS304-O stainless steel sheet (0.15 mm thick) using a flat one-turn coil. The coil is made of one copper alloy plate and is 20mm wide. In the die forming, the forming region of the die is 12mm wide, 60mm long, and has a small meandering groove with a 0.6mm depth and a corner radius of 0.3mm. An electromagnetic force generated in an aluminum sheet (driver) used as a driving plate presses the SUS304-O sheet, and causes it to bulge into the groove. The bank energy required for inducing a bulging height of 0.43mm is 4.5 kJ, and the obtained workpiece has no significant wrinkles or curves. To investigate the bulging of the SUS304-O sheet, the magnetic flux density on the driver is calculated approximately using the assumption that it is a flat sheet. Because the flux density on the flat sheet consists of two components, the electromagnetic force also consists of two components. One of them is a bulging force in the die direction. The bulging force is essentially constant within 80% on the coil width of 20mm, and controls both the wrinkles and the curves of the workpiece during the bulging operation.
