Numerical Simulation And Experimental Research On Micro Bending Process Of Pure Copper Foil

In recent years, metal foil is wide applied in electronics industry, micro electromechanical systems, medical and new energy fields. Plastic micro forming technology becomes the first choice of mass production of miniature parts for its advantages including high efficiency, high quality and low cost. With the miniaturization of specimen size, the mechanical characteristics and properties of materials exhibit strong size effect during the process of sheet metal forming, which urges us to study the mechanical parameters and deformation law of the microseale material and promote the development of micro metal foil forming technology.Tensile tests of pure copper foils with various thickness and grain size were conducted at room temperature to acquire stress-strain relationship of copper foils and investigate how the stock thickness and grain size influence the mechanical properties of materials, and provide mechanical properties for micro bending simulation.The results showed that, in the same heat treatment condition, the flow stress of material decreases with the decrease of stock thickness and shows the first size effects, when the stock thickness is more than90um. And the flow stress of material increases with the decrease of stock thickness and shows the second size effects, when the stock thickness is less than90um. When the stock thickness is the same, the flow stress decreases with the increase of grain size. In addition, the change of thickness has almost no effect on the elasticity modulus of copper foil, while grain size shows certain size effects, that is, the elasticity modulus increases with the decrease of grain size.This paper adopted two ways of numerical simulation and experiment to study the micro bending process and springback of pure copper foil. The eta/DYNAFORM was used to simulate the micro bending process and springback of copper foil based on material flow model obtained by tensile tests. The simulation results showed that the springback amount increases with the decrease of stock thickness, and the increasing trend is gradually obvious with the decrease of stock thickness, which shows the size effect of the springback amount and the thinning of thickness. The springback amount decreases with the increase of grain size, and shows the first size effects. The springback amount decreases with the increase of bending angle, and increases with the increase of die radius and clearance between punch and die. Among them, the stock thickness is the greatest impact, which increases significantly with the decrease of stock thickness.Designed and manufactured the micro bending experimental facility, which can be easily realize the experiments about different stock thicknesses, grain sizes and bending angles. The experiment results showed that iniluence laws of stock thickness, grain size and bending angle to the bending springback of copper foil are consistent with the simulation results, which indicates that the material performance parameters obtained by tensile tests, the bending process modeling, the influence laws of various factors to bending springback and the analyses about size effect are credible.