Research On Electromagnetic Incremental Forming Technology Of Large Thin-walled Aluminum Components

Large thin-walled aluminum components is a key structural part that hinders the development of aerospace and other advanced manufacturing fields.Traditional forming technology can no longer meet high index requirements of modern manufacturing in most aspects,and electromagnetic incremental forming(EMIF)technology is an process combined with electromagnetic forming and single-point incremental forming,which has advantages of both processing technology,local dynamic deformation driven by pulsed electromagnetic field gradually accumulates uneven deformation,which further improves formability,reduces defects such as springback and wrinkling in traditional processing technology,and provides a promising solution to solve the manufacturing problem of large thin-walled aluminum components.In this paper,the numerical simulation of whole manufacturing process of large thin-walled aluminum components is carried out to study influence of coil's structure,discharging path,and various process parameters on formability,the regulation of stress wave propagation during the forming process and the result indicators such as displacement,springback amount,sticking mold degree,thinning rate and so on were characterized and analyzed.According to the forming characteristics,the whole process is divided into four forming stages.Research shows that there are obvious stress wave propagation characteristics in the first four passes of sequential discharge in the free deformation stage,keeping the Z-direction displacement of the coil constant,with the increase of discharging passes,radial amplitude of stress wave increases gradually,and deformation is dominated by tensile stress,while circumferential stress changes from tensile stress to compressive stress,but mostly negative,and deformation is dominated by compressive stress.The radial stress wave propagation regulation is that closer to complex deformation zone,the wave propagation period is longer.Compared with free deformation path,the regulation of stress wave propagating on the path of obstacles maintains S₁-S₂-S₃-S₄-S₂-S₃form;but circumferential stress is that closer to the larger structural constraint zone,longer the wave propagation period,the propagating regulation of stress wave maintains the form of N₁-N₂-N₃-N₄-N₁-N₂,and entire stage has a good uniformly formed except the first larger degree of deformation because of no structural constraint before.Drawing-bulging stage simplifies the discharge path by adjusting station and discharge parameters on the basis of meeting the forming requirements.In center sticking stage,on basis of ensuring maximum sticking area,the contour shape of the mold was optimized after that a new coil structure is designed and the station parameters are adjusted,finally verified by measuring the degree of sticking mold.In sidewall sticking stage,kidney-shaped coils are designed according to the shape of the mold,the sticking mold degree in active area is used as standard to define the number of sticking and optimize the discharge path at this stage after adjusting the displacement and deflection angle in each direction.Finally,the integral forming within the 320mm radius of the billet reaches the standard and formability is good by measuring the topography.Maximum thinning rate is 10.6%,and average thinning rate is 7.35%,both meet the requirement of process accuracy.It has an important reference significance for guiding whole process of manufacturing large thin-walled aluminum components.