Numerical Simulation And Experimental Study On Electromagnetic Hole-flanging Forming Process Of Aluminum Alloy Sheet

Lightweight and high-strength aluminum alloy materials are widely used in aviation,aerospace and automotive industries to achieve energy saving and pollution reduction.The flanging forming process can be used for partial forming of large workpieces to facilitate assembly with other parts,or to increase the rigidity of the workpiece.However,with the traditional flanging process,a large set of tooling is required,which has high cost and long intermediate process.The electromagnetic flange forming does not require a flanged punch,and the mold structure is simple;the workpiece has less springback and high forming precision;the workpiece is plastically deformed under the action of electromagnetic force and inertia,does not contact with the punch,and has high surface quality;forming speed Fast and efficient;its high-speed forming features also improve the plastic forming properties of the material,so it is very suitable for the formation of difficult-to-machine materials such as aluminum alloys.Therefore,the research on the electromagnetic flanging forming process is of great significance.In order to study the round electromagnetic hole-flanging forming process,the annealed AA3003(LF21M)aluminum alloy plate round hole-flanging piece is used as the experimental material and research object,and the flanging die and coil are designed and manufactured to establish the traditional round hole-flanging and electromagnetic flanging.Experimental tooling.The finite element model of electromagnetic flanging forming with electromagnetic-structure coupling was established.The combination of numerical simulation and experimental research was used to study the process of electromagnetic franging of aluminum alloy plate.Firstly,the numerical simulation of the electromagnetic coil forming process of the flat coil and the gradient coil is carried out,and the structural deformation,magnetic field,electromagnetic force,sheet speed,and stress-strain distribution of the sheet during the electromagnetic flanging forming process of the flat coil are obtained.The results show that the electromagnetic force of the sheet material in the middle of the deformation zone is relatively concentrated,and the sheet material at the edge of the hole is firstly pasted,and the sheet material in the middle of the deformation zone is final ly unable to be molded,and the quality of the flanging is poor.Two problems were found: the flanged part failed to obtain the vertical edge and the plastic deformation unevenness of the sheet;and the numerical simulation results of the gradient coil electromagnetic flange forming showed that the electromagnetic force of the sheet at the edge of the hole was the most concentrated and had a step The electromagnetic force distribution,the die fillet,the middle of the deformation zone,and the sheet at the edge of the hole can all be pasted.The distribution of magnetic field,electromagnetic force and speed is more reasonable.For three different flanging coefficients(0.72,0.68,0.64),the sheets can be turned into vertical edges,and the innermost copper wire of the coil and the edge of the sheet are increased.The relative distance can increase the electromagnetic concentration of the sheet at the edge of the hole.Subsequently,the electromagnetic flanging experiments of the spiral flat coil and the spiral gradient coil were carried out,and the simulation results were verified.The final forming shape,the flanging height,the thickness thinning and the sticking of the flanging coefficient sheets under different discharge voltage conditions were obtain ed.Distance and so on.The results show that the flanging quality obtained by the electromagnetic coiling test of the flat coil is getting worse with the flanging coefficient.Therefore,a new multi-layer variable number gradient coil is proposed for the first problem,and the gradient coil electromagnetic flanging forming experiment is carried out.The results show that the die fillet,the middle of the deformation zone and the sheet at the edge of the hole can be sequentially Finish the model.For differ ent flanging factors,the sheet can be turned into a vertical edge with a maximum average mold clamping distance of only 0.29 mm.A concentric circular flat coil and a concentric circular gradient coil are proposed for the second problem,and experimental research shows that the flange height and quality of the flanged part are improved and the forming uniformity is improved compared with the spiral type coil.Sexual problem,reducing the mold-to-mold distance,and the average mold-fitting distance of the flanging parts obtained by the electromagnetic flanging of the concentric circular gradient coils of different flanging coefficients is less than 0.10 mm,the degree of sticking is higher,and the flanging quality is better.