شبيه‌سازي و طراحي يك سامانه مكاترونيكي مبتني بر ميدان مغناطيسي در فرآيند شكل‌دهي ورق‌هاي آلومينيومي

Simulation an‎d Design of a magneticfield based mechatronics system for forming process of aluminum sheets

مهندسي مكانيك

Electromagnetic forming (EMF) is an advanced high-speed metal forming process with significant potential for deforming metallic materials at high strain rates. In this process, a strong magnetic field is used to apply a mechanical force to the workpiece. In conventional electromagnetic forming, this force is generated by the discharge of a capacitor through a forming coil, which produces a strong transient magnetic field around the coil. The magnetic field induces eddy currents in the sheet, an‎d the interaction between the induced currents an‎d the surrounding magnetic field generates a Lorentz force that propels the sheet away from the coil at very high velocity. However, the durability an‎d service life of the forming coil, due to severe mechanical shocks an‎d cyclic thermal loads, remain major challenges that limit the industrial development an‎d application of conventional EMF. In this study, a direct-pulse-current electromagnetic forming (DPCEMF) method is developed an‎d investigated to address the structural limitations associated with conventional forming coils. In the proposed method, the vulnerable forming coil is eliminated an‎d replaced with a conductive copper block enclosed in a robust protective casing. The pulsed electric current generated by capacitor discharge is directly applied to the workpiece, generating a strong magnetic field around the sheet. The direct passage of current through the workpiece also produces Joule heating in the sheet, an‎d the simultaneous application of the Lorentz force an‎d Joule heating results in thermoplastic forming of the sheet. This coupled electromagnetic–thermal–mechanical process provides instantaneous thermal softening of the aluminum sheet an‎d consequently increases its formability limit. The proposed process is analyzed an‎d simulated using the multiphysics finite element software COMSOL Multiphysics, an‎d the numerical results are validated using experimental test data reported in previous studies. In this research, the pulsed-power supply circuit is also investigated, an‎d the effects of its electrical parameters on the discharge current, sheet temperature rise, an‎d force applied to the sheet are analyzed. In addition, the effects of deformation of the copper block on the magnitude an‎d force profile applied to the sheet are examined. Furthermore, the proposed forming process is investigated for different sheet dimensions, an‎d the corresponding results are reported. The mechanical response of the process is also eva‎luated through analysis of parameters including sheet deformation, thickness variation, strain rate, an‎d sheet ejection velocity, an‎d the corresponding mechanical analysis results are presented.

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