Electromagnetic forming with automatic feedback control of Lorentz force distribution: A new forming method and its application to high-uniformity tube deformation

It's always challenging and desirable to achieve the control of workpiece profile during electromagnetic forming. In this work, a new dual-coil electromagnetic tube forming method is proposed to achieve high-uniformity deformation of tubes with the aid of automatic feedback control of Lorentz force distribution. A series of ex-periments and simulations are conducted to demonstrate the effectiveness of this approach, and to discuss the influence of key electromagnetic parameters on the deformation behavior of AA6061-O aluminum alloy tubes as well as the underlying mechanisms. It is shown that the proposed forming method can automatically and dynamically adjust the radial Lorentz force distribution, so that the tube deformation tends to be uniform in a wide range during the forming process, and the deformation uniformity of the tube can be improved by about 2.7 times compared with the conventional single-coil electromagnetic forming. Meanwhile, it is found that the current polarity of the inner-outer coils and the power supply mode have obvious effects on the tube forming process, where the opposite current polarity and the dual power supply mode are advantageous for the forming efficiency and deformation uniformity. Furthermore, it is clearly demonstrated that high-uniformity deformation of tubes at different forming depths can be achieved, indicating that the proposed method has good applicability and flexibility. This work provides a new way to regulate the Lorentz force distribution, which is of significance to inspire new technologies and applications of electromagnetic forming.