Papers by Keyword: Electromagnetic Forming

Abstract: The rebound-effect that frequently occurs during electromagnetic sheet metal forming is one of the main causes of deviations in the shape and dimensional accuracy of flat surfaces. The selection of the die material and its corresponding energy absorption capabilities has a critical impact on this effect. This article analyses materials with different physical properties in terms of their energy absorption behavior under dynamic impact load. A variety of model tests are being conducted to examine a wide range of impact velocities and energies. The experimental setups comprise two variations of a drop tower test, which can be used to determine the percentage of impact energy absorbed at high and low momentum. To achieve higher impact velocities, a third experiment involving an electromagnetically accelerated impact body was conducted for the material that demonstrated the best result in the preceding tests.

Abstract: Flat spiral coil for electromagnetic forming system has been modelled in FEMM 4.2 software. Copper strip was chosen as material for designing the actuator coil. Relationship between height to width ratio (S-factor) of the copper strip and coil’s performance has been studied. Magnetic field intensities, eddy currents and Lorentz force were calculated for the coils that were designed using six different 'S-factor' values (0.65, 0.75, 1.05, 1.25, 1.54 and 1.75), keeping the cross-sectional area of strip same. Results obtained through simulation suggest that actuator coil with S-factor ~ 1 shows optimum forming performance as it exerts maximum Lorentz force (84 kN) on work piece. The same coils was fabricated and used for electromagnetic sheet forming experiments. Aluminum 6061 sheets of thickness 1.5 mm have been formed using different voltage levels of capacitor bank. Smooth forming profiles were obtained with dome heights 28, 35 and 40 mm in work piece at 800, 1150 and 1250 V respectively.

Abstract: A numerical simulation study of collision effect on damage evolution in electromagnetic forming (EMF) was presented. EMF technology can greatly improve the forming limit of metal sheet duo to the high rate. However, collision behavior is also an important factor for the formability of sheet. Free form model and conical die model were carried out to study the effect of collision behavior on mechanical properties of Al alloy sheet. The EMF process of 1050 Al alloy sheet was analyzed and discussed by numerical analysis software LS-DYNA. The combined strategy of boundary element method and finite element method was adopted to realize the coupling calculation of electromagnetic field and structural field. Based on the GTN material model, the evolution of void volume fraction of 1050 Al sheet were calculated and analyzed. Comparing the free form model results and the die form model results, showed that the collision behavior could reduce the void volume fraction of sheet, but excessively high collision speed lead to the sheet rebound, which aggravated the damage of material and reduce the accuracy of the product. Therefore, the appropriate discharge voltage in this work was found to improve mechanical property of sheet on the premise of forming precision.

Abstract: A new method, electromagnetic incremental tube bulging with casting pipe, has been developed to manufacture corrosion resistant bi-metal pipeline as bulging aluminium alloy tube stuck to the internal surface of casting pipe. By formulating simulation parameters, electromagnetic model and structural model to do numerical simulation. The bulging tube is more homogeneous and closer to a long-straight tube when setting a casting pipe outside the aluminium pipe. Simulation results match well with the experiment. A solenoid coil discharges at different places inside the aluminium alloy tube with casting pipe a few millimetres outside the aluminium alloy tube. The aluminium alloy tube impacts on the internal surface of casting pipe instantaneously under the repulsive electromagnetic forces. The aluminium alloy tube can not be peeled off the casting pipe when tensile force reaches to 1kN. The result demonstrates that it is feasible to produce corrosion resistant bimetallic fluid pipe using electromagnetic incremental forming. The research can provide a certain reference for electromagnetic incremental aluminium alloy tube bulging.

Abstract: A method for the virtual process design of combined quasi-static and electromagnetic forming processes based on a thorough process simulation is developed. Its flexibility is demonstrated by means of an identification problem for process parameters yielding a minimum bottom edge radius in round cup forming. Particularly, an optimum double exponential current pulse is identified. This class of pulses is parameterized as an example for pulses with mono-directed current employed to reduce the wear of the tool coil.

Abstract: To make the advantages of electromagnetic forming applicable for industrial manufacturing, a three step tool design strategy is suggested. At first, simplified decoupled electromagnetic and structural mechanical simulations are used for creating a preliminary design via a systematic iterative optimization process. The selected design is verified in more accurate coupled simulations. A prototypic realization serves for further optimization, if necessary. The applicability of the approach is proved on the basis of an inductor system for magnetic pulse welding of tubes.

Abstract: A frequent application of electromagnetic forming in the industry is joining by electromagnetic compression of tubular parts. The goodness of the joints is determined by the strength of the joint, and it is considered excellent if it reaches the strength of the weaker material pair. Strength of these joint are generally tested for tensile and torsion loadings. In order to increase strength, one or more horizontal and/or radial grooves can be fabricated onto the male joining pair to utilize form fitting besides interference fit. In the present paper, the strength of the joint is studied by finite element simulations.

Abstract: Electromagnetic forming is a high speed forming process, wherein the forming pressure is created by high energy density electromagnetic pulse. Besides direct shaping there are other application areas as well, so electromagnetic plastic forming is a potential field of creating joints between tube and rod-like components. Connecting components of dissimilar materials is an increasing demand in the manufacturing process of structures in the automotive industry. The application of new technologies, such as electrodynamic, especially electromagnetic forming, is a possible method to satisfy these demands. The article summarizes the most important fundamentals of electromagnetic forming; in particular, tube-rod joints, the main types of such joints; interference-fit and form-fit joints are described. Experiments, which were carried out producing tube-rod joints with electromagnetic forming, are also introduced. A new type of form-fit joints for tube-rod connections has been developed, which can withstand not only tensile loads but also torsion. Experiments and mechanical tests have proved the applicability of this kind of joints.

Abstract: Electromagnetic forming is a kind of processing technology that use lorentz force to make rapid prototyping of metal workpiece, which can significantly improve the metal forming performance,and it is expected to become an emerging technology that alternative to traditional machining to process light alloy materials. Based on the understanding the basic structure of the electromagnetic coupling on the basis of physical process of electromagnetic forming, this article adopt ANSYS sequential coupling method to simulate the electromagnetic coupling process of electromagnetic structure, and analysis of tube electromagnetic forming and plate of workpiece in the process of free bulging deformation behavior. The solenoid coil tubing have an axis of symmetry due to bulging, and it’s electromagnetism load and constraint has symmetry, so its formability is uniform in hoop direction. When the plank free bulge, the distribution of the electromagnetic force caused by the flat spiral coil is not uniform,and the artifacts accelerate fastest in the part of the radius of coil 1/2, but the center area of the workpiece’s forming height is highest.

Abstract: Electromagnetic forming (EMF) is a typical high speed forming process using the energy density of a pulsed magnetic field to form work sheets made of metals with high electrical conductivity like aluminium alloys, which have low formability at low strain rate. Under high velocity forming, metallic materials exhibit an increase of flow stress and ductility with increasing deformation rate. Therefore, materials of lower ductility can be deformed to higher strains using high strain rate deformation processes such as electromagnetic or explosive forming techniques. In this paper analysis of an electromagnetic sheet metal forming process is carried out by using commercial finite element software LS-DYNA^®, which incorporates a sequential coupling method involving electromagnetic field, structural and thermal solutions. Study of process parameters for forming aluminium ice tray (used in refrigerator) by Electromagnetic forming process has been carried out, simulation was done involving a die, Al worksheet and a spiral coil.