Tp2 Copper Tube Induction Annealing And Final Annealing Study

Rapid economic development promotes the development of air conditioner market, air conditioner quality requirements is increasingly demanded by the application of the new generation of refrigerant (such as R134a), while with the increased awareness of environmental protection, inner-grooved TP2 copper tube has become the first chosen efficiency heat transfer tube that products heat exchanger, including evaporator and condenser, it appears in green CFC-free air conditioning and refrigerator. The heat exchanger develops toward the high performance, small size and low quantization direction, it leads copper tube to the high cleaning, high performance, high precision and high value-added direction, so copper processing industry have to go professional, efficient large-scale road. Annealing process is especially important in the copper production, in-line induction annealing controls yield rate of inner-groove forming, and final annealing controls the microstructure and mechanical properties of final products, so studying the copper tube annealing process has meaningful guidance for the production of copper tube.The thesis comes from National Key Technology R&D Program of China——production technology of large-diameter plastic covered inner-grooved copper tube. The object of study is TP2 copper tube, combining with induction heating theory, the mathematical model during in-line induction annealing process is established, use of finite element software DEFORM-2D to simulate temperature field of copper tube, also main influencing factors on temperature distribution are analyzed. Mechanical properties of in-line induction annealing copper tube are tested so that main influencing factors on microstructure and mechanical properties are analyzed. The main process parameters of in-line induction annealing are line speed and voltage so that the relationship between the main process parameters and geometry of copper tube is analyzed, and its mathematical model is established, thus it provides a theoretical basis for developing annealing process parameters. Finally, mechanical properties of final annealing copper tube are tested so that the reason for unstable mechanical properties of copper coil tube and hard-core are analyzed.After simulation of in-line induction annealing, it shows that line speed, current density, heat frequency, size of inducting coil and size of copper tube affect the temperature distribution. During the annealing process, skin effect occurs in copper tube, also according to a large number of experimental data, medium frequency induction heating is an optimal choice. After testing mechanical properties, it shows that grain size, geometry of copper tube and ambient temperature affect the microstructure and mechanical properties of copper tube. After analyzing the main parameters, it shows that the mathematical model of line speed-voltage curve is U = A+B₁V l +B₂V_l². Finally, after testing mechanical properties of final annealing copper tube, it shows that grain size of surface is larger than the core's, and the core is stiff. The temperature difference between surface and core can be used for early entry into the cooling stage to reduce the overheating of the time the surface of copper tube during production so that the microstructure and mechanical properties of the surface and the core of copper coil tube are consistent.