Numerical Simulation And Experimental Study Of Copper Cladding Aluminum Electric Flat Bar In The Rolling Process

As a new conductor, copper cladding aluminum (CCA) conductive flat bar has many advantages, such as low weight and less cost. It could be widely used as conductor of high-intermediate frequency heater, large junction bar of chemical and metallurgy industry, etc. A new process is presented to use CCA composite round billets to prepare conductive bar by flat rolling.Deformation behavior of CCA round billits in flat rolling process has been investigated with rigid plastic finite element, and effect of process parameters on rolling behavior and thickness distribution of copper cladding layer is analysed. At last, effect of reduction rate and depressing schedule on spread and thickness variation of copper cladding layer is studied.Finite element simulation and experiment results show that the spread conform to obvious linear relationship with reduction rate. Sidepiece deformation spreading is dominant during the first flat rolling pass. Influence of slip spreading enhances, while effect of sidepiece deformation spreading reduces during the later passes. Friction factor increase between roller surface and the rolled piece is beneficial to big spread and obtain uniform copper layer as CCA rod rolling, the same to roller diameter. Under the alloying of the rolling equipment and the tensile stress of the copper layer edge smaller than the tensile strength of copper, the first flat rolling reduction rate should be enlarged to enhance the binding force of copper and aluminum layer; when the reduction rate of the second flat rolling increased, the uneven degree of the copper cladding increased, too, which would lead to the crack of the metal of copper cladding layer edge. Billet reasonable agreement of the FEM predictions and the experimental results has been obtained. When the total reduction of CCA rod is fixed, flat bar that has good surface quality and uniform thickness of copper cladding layer, without apparent crack at the sidepiece and lamination at the composite interface, can be prepared by proper rolling process. With the reduction rate and the rolling speed increases, the risen degree of the temperature of the rolled piece at deformation zone increased. The surface temperature of copper and copper clad aluminum row and side temperature of aluminum conductor were higher than that of middle part the temperature. Before rolling, temperature should be elevated suitably to reduce rolling pressure and to accelerate the flow of the CCA. Elevating the annealing temperature and extending the annealing time can increase the thickness of transition layer of joint surface of copper and aluminum.During the process of using CCA composite round billets to prepare conductive bar by flat rolling, it should be reduce the times of flat rolling pass, increase the reduction of the first flat rolling pass, elevate the rolling temperature, decrease the coefficient of friction and increase the diameter of the roller.