Research On Three-dimensional Stretch Bending Simulation And Die Surface Design Method Of Aluminum Alloy Profile

Aluminum alloy profile has the characteristics of low density,high strength and good processing performance.It is often used to process bending frame parts with complex three-dimensional shape.It has been widely used in aerospace,high-speed train manufacturing and other fields.The research on the forming mechanism and forming quality control method of three-dimensional stretch bending of aluminum alloy profile is of great significance to promote the development of transportation industry in China.This paper studies the three-dimensional stretch bending forming process of profile,puts forward the compensation design method of three-dimensional stretch bending die surface,and develops a plug-in program with the functions of finite element analysis and die surface compensation design based on the python interface of ABAQUS,which is described as follows.(1)The three-dimensional stretch bending of profiles is analyzed mechanically.The geometric characteristics of the three-dimensional bending part of the profile are studied and obtained from the perspective of differential geometry.Deformation law of profile three-dimensional stretch bending is analyzed and strain law is expressed by spatial deformation law of profile.The width of section in radial direction is analyzed,the mechanical characteristics of three-dimensional stretch bending of section are studied in combination with the theory of sheet metal bending engineering,and the mechanical calculation model of three-dimensional stretch bending load bending moment and spring-back of section is established.The results show that the loading bending moment and spring-back are mainly affected by the stress difference of section.(2)The key factors and parameters of three-dimensional stretch bending process of profile are studied by finite element simulation.The spatial motion trajectory of the clamp is calculated,and the finite element model of three-dimensional stretch bending of profile is established.The stretch bending and spring-back processes of three-dimensional bending parts with various curvature radii and under different friction conditions are simulated respectively.The effects of the target shape and the friction coefficient between the profile and the die on the stress-strain distribution,shape error and section distortion of three-dimensional stretch bending of profile are analyzed.The two main process parameters of pre stretching and supplementary stretching are selected,and the action laws of the two process parameters on the three-dimensional stretch bending of profiles are obtained through simulation experiments,which can provide effective guidance for the parameter selection and process optimization of three-dimensional stretch bending of profiles.(3)The compensation design method of die surface is put forward.Following the idea of discrete fitting,starting with the spatial shape of profile three-dimensional bending part,the element body discrete method of profile three-dimensional bending part model is proposed,and the spring-back compensation model of profile element body is established based on the deformation behavior of element body.The theoretical compensation obtained by the mechanical analytical formula and the simulation compensation output from the finite element simulation results are used to compensate the die surface.The results show that the die surface designed by the simulation compensation has a better effect on improving the forming accuracy of stretch bending.(4)The design platform of three-dimensional stretch bending die for profile is developed.Combined with the standard interface language of ABAQUS software,the calculation process of profile three-dimensional stretch bending clamp track and the design and calculation process of compensation die surface are compiled into executable Python script program,and a concise and humanized user graphic interaction interface is established.A 3D stretch bending die design platform is developed by combining stretch bending finite element simulation,data processing and die surface design.The results show that the platform greatly improves the efficiency of die surface design and has strong engineering practicability.