Speaker
Description
Electromagnetic forming (EMF) is a significant application direction of pulsed high magnetic fields. As a high-speed forming technique, EMF offers typical advantages associated with high forming rates, such as enhancing the material forming limit, suppressing wrinkling and springback. Additionally, the driving force in EMF is a non-contact force, eliminating the need for a force transmission medium and enabling high-quality forming surfaces. The magnet responsible for generating the magnetic field is one of the most critical components in EMF. The design of magnets based on the structure of the field shaper involves optimizing the shape of an additional metal block within the magnet. Compared to magnets that rely solely on coil windings for field generation, such designs provide a richer force field and enhance the mechanical strength and lifespan of the magnet.However, current field shaper designs for metal sheet forming are primarily based on axisymmetric structures, optimizing the force field only in the radial direction. This one-dimensional optimization limits improvements in the uniformity of the force field of the field shaper.
This paper presents a multi-stage optimization method for field shapers, decoupling the field shaper's structural parameters into basic structural parameters and bottom structural parameters . Based on the structural characteristics of the field shaper and leveraging software advantages, different simulation models are established to ensure computational accuracy while improving computational efficiency. First, a two-dimensional COMSOL model is developed based on a cylindrical field shaper to determine the basic structural parameters of the field shaper. A more accurate three-dimensional COMSOL model is then created, with the bottom surface structure parameterized. The effects of the bottom surface height distribution of field shaper in the radial and circumferential directions on the electromagnetic force distribution are analyzed, and the design range for the bottom structural parameters is determined. Finally, an electromagnetic-structural field coupling simulation model is developed using LS-DYNA, the bottom structural parameters are finalized, and the electromagnetic force distribution and forming capabilities of the field shaper are validated. Simulation results show that the field shaper designed using this method achieves precise control over the radial and circumferential distribution of the electromagnetic force and allows flexible control of the workpiece deformation behavior.Based on the simulations, a large-scale aluminum alloy sheet metal forming experimental platform is established. The field shaper is used to form a 1000 mm radius, 4 mm thick A1060 aluminum sheet. Experimental results demonstrate improved workpiece forming uniformity and thinning, thereby validating the feasibility of the proposed field shaper design method.
