Study On Cu/Al Sandwich Composite Experiment And Numerical Simulation During Cold Rolling

Copper/aluminum/copper sandwich composite material with good electrical conductivity,high thermal conductivity,light weight and low cost characteristic has wide application prospects in modern industries like power cables,packaging materials,radiator fin.Since there are some deformations between the metal sheets the production of the sandwich sheet can be more complex.Also without supporting the rolling theories the models for sandwich rolling are always based on production experiences.So the studies for sandwich rolling are significant for national production.In this paper,the copper aluminum sandwich composite sheet by cold rolling are studied through the experiment and finite element numerical simulation method.Symmetrical and asymmetrical cold rolling with different thickness reduction are used to study composite's interface bond strength and bond surface based on the experiments.Annealing experiment is also conducted to find the impact on composite plate bond strength and interfacial diffusion with different annealing temperature and annealing time.This can be used to provide the guidance for the establishment of annealing process in practical production.The effects of symmetrical and asymmetrical thickness reduction and asymmetrical roller speed ratio on composite board interface stress,strain distribution and the metal deformation law of mechanics behavior is studied with the finite element numerical simulation method.The main contents are as followings:(1)Thickness reduction rate and asymmetrical speed ratio are important factors which affect the bond strength of composite sheet.The bond strength of composite is researched respectively during symmetrical and asymmetrical rolling under different thickness reduction.The bond strength of composite material in symmetrical and asymmetrical rolling is compared under the same rate of thickness reduction.(2)Cu/Al composite material after cold rolling is treated adopting different annealing process.And then the type and content of the intermetallic compound which forms during diffusion are judged from the aluminum side to the copper side.The changes of diffusion layer thickness and content in composite sheet interface are studied under different annealing temperature and time.Furthermore,the influences of the compounds' type and content on the bond strength of composite sheet are investigated.(3)The effect of rolling parameters on Cu/Al sandwich composite rolling are analyzed by finite element numerical simulation method.The distributions of rolling pressure and friction stress in the contact arc,as well as the distribution of effective strains along the thickness direction are research under various thickness reduction rate in symmetrical rolling.In asymmetrical rolling,the influence of speed ratio on the CSR size under same thickness reduction,and the effect of thickness reduction on the CSR size under same speed ratio are investigated.The bond strength of composite sheet is explained from stress and strain distribution of rolling deformation zone.(4)The deformation rates of copper and aluminum are researched through comparing the final thicknesses measured in experiment with these calculated in numerical simulation.the deformation rate differences between the two metals are obtained under different thickness reduction rate.