Research On Electromagnetic Actuator Design,Force Field Control And Forming Process Of Sheet And Tube Metal Flanging

Metal flanging workpiece,such as aluminum alloy and steel,has important application value in aerospace,automobile manufacturing and other fields.However,the traditional quasi-static flanging process of these metals is faced with problems such as poor formability,easy to crack,rebound and wrinkle.Electromagnetic flanging,as a high-speed forming technology based on pulsed electromagnetic force,has outstanding advantages in improving the forming limit of materials,restraining wrinkling and springback,so it provides an effective way to realize high performance flanging of metal components.However,the further development of electromagnetic flanging technology is restricted by the poor generality of forming coils and the difficulty of controlling workpiece forming accuracy due to the difficulty of flexible control of electromagnetic forming field.In order to break through the above bottleneck,a coil-field shaper actuator with adjustable magnetic field distribution is proposed in this paper,aiming at high-precision flanging of multi-type(such as tubes and sheets),multi-material(such as aluminum alloy with high conductivity and steel with low conductivity)and multi-shape(such as round hole,racetrack hole,triangle hole and hexagonal hole)workpieces,a new method of electromagnetically driven forming by coil-field shaper actuator and conductive foil is developed,and a new structure of coilsplit field shaper actuator is designed.The electromagnetic force field control,deformation behavior and forming quality control of workpiece in flanging process are studied systematically.The design scheme of the coil-field shaper actuator is analyzed.Considering the forming efficiency and processing cost,the size parameters of the actuator are optimized,and its mechanical strength and temperature rise are checked.On this basis,the experimental platform and simulation model of electromagnetic flanging are built,which provides an analytical means for the follow-up research.Electromagnetic flanging of aluminum alloy sheet and tube are studied based on the coil-field shaper actuator.The different influencing mechanisms of field shaper seam on the sheet and tube forming are investigated.The results show that the forming accuracy and uniformity of sheet and tube are improved by placing the field shaper seam on the top of the maximum deformation area of sheet or the minimum deformation area of tube.On this basis,the electromagnetic force field and dynamic deformation behavior characteristics of sheet and tube in the multi-step flanging process are analyzed,and the high precision flanging of sheet and tube is realized.In addition,the regulation law of discharge energy on workpiece flanging quality in multi-step forming is further investigated,and the ability of the coil-field shaper actuator to regulate electromagnetic force field and forming quality is proved.Electromagnetic flanging of steel sheet is studied based on the coil-field shaper actuator.Aiming at the problem that it is difficult to adopt traditional electromagnetic driving method for curved steel sheet in multi-step flanging,an electromagnetic forming method driven by coil-field shaper actuator and conductive foil is proposed based on the analytical model of workpiece magnetic pressure,and a simplified simulation model is established with copper foil driven electromagnetic flanging of Q160 steel sheet as the specific object,which solves the problem that the real simulation model is too slow to calculate and even difficult to converge.On this basis,the influence law of the conductive foil geometry on electromagnetic force field and the deformation of steel sheet is revealed,and the steel sheet realizes uniform flanging under single loading and high-precision flanging under multi-step loading.In order to expand the applicability and application range of the above coil-field shaper actuator.,the structure of the coil-separate field shaper actuator is further proposed,the coupling mode between the separate field shaper and the influence of geometric parameters on the forming efficiency are analyzed,and a multifunctional electromagnetic flanging platform is developed.The results show that the separation field shaper avoids the problem of electric contact and realize the effective transmission of magnetic energy by means of electromagnetic induction.So it is successfully applied to flanging many kinds of holes such as round,racetrack,triangle and hexagon.