China is a country rich in copper and aluminum. The annual consumption of current carrying conductor materials in China's electrical industry accounts for nearly one-third of the total consumption of copper in the world. Therefore, copper has become another important strategic resource in China in addition to oil. Since the 1990s, with the intensification of the shortage of non-ferrous metal resources, the price of copper has risen sharply, resulting in a significant increase in the production and use costs of copper manufacturers and customers. Therefore, on the basis of ensuring the service performance of the original copper materials, the development of new materials to replace traditional materials has become a hot spot in the research and development of domestic and foreign production enterprises. The use of alternative composites to reduce the raw material cost has become a development trend of copper production and application at home and abroad.
Metal copper has good conductivity and welding performance, but resources are scarce, processing is expensive, metal aluminum has good conductivity and relatively low price, but the welding, arc extinguishing, wear resistance, conductivity and thermal conductivity of aluminum are worse than those of copper. It is difficult to directly replace copper with aluminum on many occasions. Forming copper-clad aluminum composite strip with copper-clad aluminum can not only save the consumption of metal copper, It can also maintain the ductility, conductivity, weldability and corrosion resistance of pure copper materials. In addition, China is rich in aluminum resources. The price of aluminum is lower than that of copper, and its density is less than 1 / 3 of that of copper, which means that under the condition of the same weight, the length of aluminum is three times that of pure copper. Especially in the communication field, the frequency of cable TV signal and mobile communication signal is high, generally at 500-800mhz. Due to the "skin effect", the high-frequency current is concentrated on the surface of the conductor for transmission. When pure copper is used for information transmission, the copper in the center does not play the role of main signal transmission. Therefore, it is a very ideal method to partially replace the copper in the middle layer with aluminum, It can greatly save the scarce and expensive copper resources in China. In fact, it is not only in the field of communication, but also in the field of power transmission to replace the copper strip with CAC bimetal sheet aluminum, which is widely used and in great demand. It is expected to form a huge industry.
There are many production methods of metal composites, which can be divided into solid-solid composite method and liquid-solid composite method. The solid-solid composite method includes rolling composite, explosive composite, extrusion drawing composite, welding method, etc. the liquid-solid composite method includes core filling continuous casting, double mold continuous casting, etc. Among them, rolling method is the most widely used. The conventional compound rolling technology adopts the one-time compound technology in the production of CAC bimetal sheet aluminum. For the production of large-size composite strip, the effect is obvious, the process is stable and the production efficiency is high. However, for the lamination of ultra-thin tapes with a thickness of less than 0.15, the effect of using the one-time lamination technology is not good, which is manifested in low dimensional accuracy, difficult to control the thickness ratio of three-layer composite tapes, low production efficiency and high scrap rate. Therefore, the application of this technology is relatively limited.
The two-step composite rolling method of CAC bimetal sheet aluminum is an efficient production method of copper / copper / copper / copper three-layer ultra-thin composite belt. When preparing copper / aluminum / copper double-sided composite belt, the rolling composite of copper / aluminum single-sided composite belt shall be carried out first. The thickness ratio of copper belt to aluminum belt is 1:1, and then the secondary rolling composite of aluminum surface of copper / aluminum single-sided composite belt shall be carried out, The copper / aluminum / copper double-sided composite tape is obtained, and the thickness ratio of each layer is copper: aluminum: Copper = 1:2:1. Using the composite strip prepared by this method, the amount of copper strip can be saved by 50%.
