Research On Effect Of Process Parameters On Springback Of Warm Forming For AA5754 Aluminum Alloy Sheet

Under the restraints of resources and environment, lightweight of automobile becomes the development trend of current auto industry, and lightweight of vehicle body is the key technology of lightweight of automobile. Aluminum alloy becomes the ideal material of lightweight of vehicle body for its predominances such as small mass, adequate reserves, simple preparation, high recovery rate and so on. However, the plastic deformation capacity of aluminum alloy is poor at room temperature, and there is a serious springback problem in deep drawing, affecting the geometry and dimension precision of parts. In order to improve the springback problem, the warm forming technology of aluminum alloy sheet emerges as ·the times require.Firstly, the theoretical analysis method is applied to investigate the state of stress and strain of blank in deep drawing process. Meanwhile, the numerical simulation of split-ring experiment for cylindrical warm drawing cups is performed, and the simulation result is compared with experiment result. Secondly, the springback property of aluminum alloy cylindrical drawing cups with different process parameters is investigated by orthogonal test design method in conjunction with numerical simulation method during warm forming process, the optimization scheme minimizing springback is determined, which is validated by numerical simulation method. Finally, based on regression orthogonal test design, a regression model of relationship between springback and process parameters, including initial forming temperature of blank, friction coefficient, blank holder force, die radius and die clearance, is established for warm forming of aluminum alloy, by the numerical simulation of split-ring experiment for cylindrical warm drawing cups. The regression model is applied to predict the springback, whose result is compared with the ones of experiment and numerical simulation.The research indicates that:(1) The numerical simulation result is close to experiment result, indicating that the numerical simulation result is reliable, and the finite element model is proper.(2) During aluminum alloy warm forming process, in view of the significant level of the effect of process parameters on springback, the effect of initial forming temperature of blank is the strongest, blank holder force takes the second place, followed by die radius, die clearance and friction coefficient, while the effects of punch velocity and punch radius are almost negligible.(3) In a certain range of process parameters, the springback amount of cylindrical drawing cup decreases with the increasing of initial forming temperature of blank, blank holder force and friction coefficient. And the springback amount first increases then decreases with the increasing of die radius. Meanwhile, the springback amount first decreases then increases with the increasing of die clearance.(4) The regression model indicates that:the interactions between the process parameters are negligible, and the effects on parts springback from process parameters, including initial forming temperature of blank, friction coefficient, blank holder force and die radius, are significant. Meanwhile, there is a good additivity on the effects of the process parameters.(5) The regression prediction result is close to the ones of experiment and numerical simulation, indicating that the regression model is reliable, which reflects the relationship between parts springback and process parameters accurately during aluminum alloy warm forming process.