Electromagnetic incremental forming (EMIF): A novel aluminum alloy sheet and tube forming technology

A new two-step electromagnetic forming (two-step EMF) which combines electromagnetic forming (EM forming) with electromagnetic calibration (EM calibration), is proposed for local features of large-size sheet metal parts, such as an oblique hole-flanging. During the process, the workpiece is firstly electromagnetic formed by a flat spiral coil and then electromagnetic calibrated by a helix coil with a similar shape to the final profile of the workpiece. To develop the process, an efficient geometric design method is established, the effects of key process parameters on forming quality are investigated, and the deformation behavior of the workpiece is revealed. The feasibility of two-step EMF is validated by the accurate oblique hole-flanging with a maximum die-fitting gap less than 0.2 mm. Moreover, experimental results show that there are critical discharge voltages for both EM forming and EM calibration which lead to the minimum die-fitting gap. Furthermore, EM calibration can reduce the die-fitting gap to 0.24~1 times of that for EM forming with more uniform distribution. In addition, simulation results show that during EM calibration, the stress distribution of the workpiece is improved, the bending moment is reduced which is responsible for the shape and size errors, then the rebound is restricted. Consequently, the fittability and forming accuracy are significantly enhanced.

Two-step electromagnetic forming: A new forming approach to local features of large-size sheet metal parts

Investigation of the Lorentz-force-driven sheet metal stamping process for cylindrical cup forming

In the conventional electromagnetic tube expansion, the end effects generated by the conventional helix coil may lead to inhomogeneous tube deformation in the axial direction. This paper is aimed at overcoming this issue by proposing a new concave coil structure to replace the helix coil currently used by the industry practice to generate a radial electromagnetic force on the tube. The proposed concave coil is expected to reinforce the electromagnetic force distribution profile and, hence, improving the axial inhomogeneous deformation of the tube. In this context, a new R-L criterion of deformation uniformity is first proposed. Second, an electromagnetic-structural coupling finite element model is established to investigate the relationship between the distribution of electromagnetic force generated by the concave coil and the uniformity of the tube under various voltage levels. The effectiveness of the proposed method is validated through a series of experimental and simulation analyses. Furthermore, based on the characteristics of the electromagnetic tube expansion, a modified multilayer concave coil structure is proposed to overcome the axial inhomogeneous deformation of long tubes.

/pdf/electromagnetic-force-distribution-and-deformation-r8x4o8tcw2.pdf

Electromagnetic Force Distribution and Deformation Homogeneity of Electromagnetic Tube Expansion With a New Concave Coil Structure

Large-scale sheet deformation process by electromagnetic incremental forming combined with stretch forming

Numerical modeling and deformation analysis for electromagnetically assisted deep drawing of AA5052 sheet

http://www.ysxbcn.com/down/paperDown.aspx?id=26876

Da-hai Liu

Papers

Numerical modeling and deformation analysis for electromagnetically assisted deep drawing of AA5052 sheet

Tendency of homogeneous radial deformation during electromagnetic compression of aluminium tube

Quasi-static-dynamic formability of AA5052-O sheet under uniaxial and plane-strain tension