Research On Ultrasonic Vibration Assisted Bulging Technology Of 5052 Aluminum Alloy Spherical Caparray

With the development of the electronics industry,the requirements for micro-parts in the industrial field have a sharp increase,and the metal sheet micro forming technology has the advantages of low production cost and high forming precision,therefore,micro forming technology has been more and more widely applied.At the same time,with the development of miniaturization of products,the micro-parts produced by traditional micro forming technology can not meet the requirements of industrial development.Therefore,many scholars at home and abroad have studied new thin sheet micro forming technology—ultrasonic vibration assisted micro forming,it was found that the application of ultrasonic vibration during plastic processing can improve the surface quality and forming accuracy of the formed parts.At present,there are few researches on ultrasonic vibration assisted micro-bulging technology of spherical cap arrays at home and abroad.Therefore,the paper proposes ultrasonic vibration assisted sheet metal micro-bulging technology,and the subsequent microbulging process is to adopt EVA soft mold instead of the traditional rigid punch,in order to study the effect of soft mold on the forming quality of spherical cap array parts.Micro-tensile experiments were performed on 5052 aluminum alloy thin sheet with thickness of 50?m,it was found that the hardening index of the material was the highest at 600°C,and the uniform deformation capability was the best.After the vibration was applied,the flow stress of the material was reduced,the hardening index was increased,and the hardening index at 600°C was increased from 0.42 to 0.48,therefore the formability of the sheet was improved;the effect of vibration loading time on the mechanical properties was studied with an amplitude of 5?m,it was found that the flow stress of the material was reduced by about 34 percent at the moment of vibration loading,and when the loading time reached 40 s,the tensile strength of the material was reduced by approximately 6.6 percent;with the increase of amplitude,the material flow stress decreases with a greater amplitude.the flow stress was reduced by about 47.8percent when the amplitude reached 6.2?m;the thin sheet with different thicknesses show the “smaller and weaker” size effect and after the vibration is applied,the material has a "softening" effect.By the numerical simulation of the micro-bulging process of the thin sheet,it is found that when the die corner radius is 0.3mm and the friction coefficient is 0.13,the wall thickness thinning rate of the spherical cap array part is the lowest,and the forming parts have the least tendency to crack;it is found that vibration can reduce the strain concentration of the bulging parts,improve the wall thickness reduction of the bulgingparts,and increase the forming limit of the bulging parts,when the amplitude is 2?m,the forming performance of the bulging parts is the best;soft mold assisted microbulging technology can increase the deformation uniformity of the bulging parts,and increase the wall thickness of the intersection and the bottom of the spherical caps,therefore the cracking tendency of these parts is reduced,and the forming performance of the bulging parts is improved.The rigid punch-assisted thin sheet bulging experiment is carried out through the change of the amount of reduction,heat treatment temperature,sheet thickness,it is found that with the increase of the amount of reduction,the contour of the junction edge,the junction and the bottom of bulging parts are more clearly,and the forming accuracy of bulging parts is more higher;When the reduction amount is 1.1mm,only the bulging parts at 200°C breaks at the intersection,which means that increasing the heat treatment temperature can increase the forming limit of the bulging parts;when the sheet thickness is 80?m and 100?m,the forming limit of the bulging parts is more higher,and no cracking occurs;After the EVA soft mold is applied,the surface quality of the bulging parts is greatly improved,and the surface roughness is lower and the moldability is better,the length of the intersection edge and the design value are only about 5?m apart.The vibration-assisted sheet micro-bulging experiment indicates that the ultrasonic vibration can improve the die attach ability of the bulging parts,when the amplitude is75 percent,the surface quality and moldability of the bulging parts are the best,the surface roughness decreases from 2.29 to 2.11,at the same time,compared with no vibration,the bulging height was increased by 9.6 percent;the bulging parts formed by the vibration assisted soft mold is compared with the parts formed by the vibration assisted rigid punch,the former has a better surface quality and contour shape,and with the increase of the vibration loading time,the surface quality and the moldability of the bulging parts are gradually increased,when the loading time is 300 s,the bulging height is increased by about 7.7 percent,and reaches about 1.01 mm,the length of the intersection is about 2.3112 mm,which is basically the same as the design value of2.31 mm.