Formability evaluation for low conductive sheet metal by novel specimen design in electromagnetic forming

The sheet metal forming of copper, aluminum alloys using conventional stamping processes posses various problems, because of the lower formability limits, spring back and the tendency to wrinkle compared to steel. The principle of electromagnetism using attractive force is adopted to modify the conventional stamping process, to form thin sheets of 0.05 mm thickness. Further, this process can be used to form many sheet metal components with less expensive tooling and lesser number of operations. This process ultimately leads to light weight, cost effective and better strength-to-weight ratio components required for aerospace applications. In this study, a maximum of 30.77 % reduction in diameter was observed at 2.75A using electromagnetic forming which leads to the absence of spring back.

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Analytical Design and Implementation of a Uniform Pressure Actuator for Electromagnetic Forming and Welding

Volume 1: Processing ◽

10.1115/msec2013-1238 ◽

2013 ◽

Cited By ~ 1

Author(s):

E. Thibaudeau ◽

B. L. Kinsey

Keyword(s):

Sheet Metal ◽

Analytical Modeling ◽

Electromagnetic Forming ◽

Design Parameters ◽

Magnetic Pulse ◽

Uniform Pressure ◽

Coil Design ◽

Element Analysis ◽

The Ohio State University ◽

Pulse Welding

Lightweight sheet metal components and assemblies formed and welded electromagnetically can be implemented in various industries such as automotive, aerospace, and electronics. Past applications and modeling of Electromagnetic Forming (EMF) and Magnetic Pulse Welding (MPW) have typically focused on crimping and expansion of tubular workpieces. While some Finite Element Analysis (FEA) packages exist that are capable of modeling these processes, there is a lack of simplified analytical modeling efforts, especially for sheet metal workpieces. Analytical modeling is attractive for its simplicity and cost in effectively determining e.g., an optimal coil design. In this paper a coil design and analysis procedure developed at The Ohio State University is modified and extended through an analytical model and FEA. The coil, named a Uniform Pressure Actuator (UPA), offers increased forming efficiency and repeatability, as well as a robust design. Coil design parameters such as the number of turns and conductor cross section are determined for a given workpiece. Magnetic pressure applied to the workpiece and workpiece velocity are predicted to ensure impact velocities are sufficient for MPW. A coil was constructed based on the analyses, and experimental results are compared to the analytical predictions for both electrical characteristics and workpiece velocity.

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Numerical and Experimental Investigation of the Impact of the Electromagnetic Properties of the Die Materials in Electromagnetic Forming of Thin Sheet Metal

Journal of Manufacturing and Materials Processing ◽

10.3390/jmmp5010018 ◽

2021 ◽

Vol 5 (1) ◽

pp. 18

Author(s):

Björn Beckschwarte ◽

Lasse Langstädtler ◽

Christian Schenck ◽

Marius Herrmann ◽

Bernd Kuhfuss

Keyword(s):

Electromagnetic Wave ◽

Sheet Metal ◽

Thin Sheet ◽

Electromagnetic Forming ◽

Electromagnetic Properties ◽

Relative Magnetic Permeability ◽

Die Materials ◽

Thin Sheet Metal ◽

Specific Electric Resistance ◽

The Impact

In electromagnetic forming of thin sheet metal, the die is located within the effective range of the electromagnetic wave. Correspondingly, a current is induced not only in the sheet metal, but also in the die. Like the current in the workpiece, also the current in the die interacts with the electromagnetic wave, resulting in Lorentz forces and changes of the electromagnetic field. With the aim to study the influence of different electromagnetic die properties in terms of specific electric resistance and relative magnetic permeability, electromagnetic simulations were carried out. A change in the resulting forming forces in the sheet metals was determined. To confirm the simulation results, electromagnetic forming and embossing tests were carried out with the corresponding die materials. The results from simulation and experiment were in good agreement.

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Determination of Plastic Material Properties of Thin Metal Sheets under Electromagnetic Forming Conditions

10.25518/esaform21.850 ◽

2021 ◽

Author(s):

Björn Beckschwarte ◽

Marius Herrmann ◽

Christian Schenck ◽

Bernd Kuhfuss

Keyword(s):

Magnetic Field ◽

Electromagnetic Field ◽

Sheet Metal ◽

Material Properties ◽

Plastic Material ◽

Electromagnetic Forming ◽

Material Behavior ◽

Process Conditions ◽

Force Transmission ◽

The Magnetic Field

Electromagnetic forming is a contactless high-speed forming technique. In this process force transmission is initiated by an electromagnetic field provided by a tool coil. While forming thin sheet metal, the magnetic field is present in the whole depth of the sheet metal by definition. Thus, the magnetic field generates eddy currents in the complete sheet volume. The resulting Lorenz` forces act as body forces and are used for forming. Thereby high strain rates, high temperatures and multiaxial stress fields influence the plastic material properties of the workpiece. In this study, the plastic properties were investigated under real electromagnetic forming conditions. By varying process conditions like charge energy, sheet thickness and die material, the magnetic field and thus the plastic material properties were changed. To visualize the influence of the electromagnetic field, forming experiments were carried out. The strain of the formed sheets was measured. Furthermore, the forming forces were determined by measurements during the electromagnetic forming as well as by finite element simulations. With the measured strain and the determined forming force, a model for the plastic material behavior during electromagnetic forming was evolved.

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Large Ellipsoid Parts Manufacture Using Electromagnetic Incremental Forming With Variable Blankholder Structure

10.21203/rs.3.rs-308311/v1 ◽

2021 ◽

Author(s):

Xiaohui Cui ◽

Yan Ziqin ◽

Chen Baoguo ◽

Du Zhihao ◽

Xiao Ang ◽

...

Keyword(s):

Numerical Simulation ◽

Compressive Stress ◽

Sheet Metal ◽

Incremental Forming ◽

Sheet Material ◽

Electromagnetic Forming ◽

Blank Holder ◽

Load Bearing ◽

Metal Thickness

Abstract The large ellipsoid parts are the main load-bearing components in the rocket tank, which are prone to wrinkle when using the traditional stamping. In order to solve the wrinkling problem in large parts, the EMIF method with a variable blank holder is proposed in this paper. The numerical simulation has shown that the sheet material near the blank holder is, as a consequence of stamping, subjected to circumferential compressive stress. When the drawing height was 100 mm, the sheet metal was notably wrinkled. In the electromagnetic forming (EMF) process, the sheet region facing the coil becomes thinner. However, the sheet metal thickness corresponding to the coil edge increases with the increase in forming height. If the EMF forming height is 150 mm, the sheet, which is in contact with the smooth mold, is deformed without a wrinkle. Compared to the traditional stamping, the EMF can significantly reduce the sheet metal wrinkling, improving the deformation height of the sheet metal smooth area.

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