ã€China Aluminum Industry Networkã€‘ 1. Typical production processes and performance control of auto body aluminum panels Under the global situation of advocating energy conservation and environmental protection, the lightweight technology application of the automotive industry has been put on the agenda. The application of aluminum alloy panels for automotive panels is a simple and effective lightweight method. Automotive aluminum sheet is one of the high-end aluminum alloy varieties. Due to the stringent requirements on the performance (formation, connection, etc.) and surface quality, the automotive aluminum sheet also provides more detailed control and management requirements for the processing of raw materials.
The automotive aluminum production process is shown in Figure 1. The aluminum liquid is continuously cast into aluminum billets of different specifications. After surface treatment and heating, hot rolling, coiling, and cold rolling are performed to obtain the desired thickness, and then the continuous annealing heat treatment is performed to obtain the desired microscopic fine structure and performance.
There are many key technologies and difficulties in the production of automotive aluminum sheet materials, and will also have an important impact on the subsequent use of performance (pressing, painting, etc.).
Throughout the automotive aluminum production process, from the perspective of the microstructure can be simply attributed to two aspects: cleanliness (chemical metallurgy process) and uniformity (physical metallurgical process). Reflected in the actual large-scale production process is the control process of smelting (casting) and rolling (heat treatment). Excellent aluminum liquid cleanliness and organizational (texture) uniformity have a positive effect on the press forming and joining properties of subsequent automotive plants. The homogeneity of the texture (texture) includes both the size of the grain size of the matrix structure and the proportion of the micro-texture that favors the formability. The macroscopic external appearance of material use performance is based on its microscopic intrinsic nature. With reasonable control of the microstructure and texture, the desired macroscopic properties can be obtained.
In view of the mismatch between the production time of raw material aluminum plants and automobile plants, the natural aging of automotive aluminum plates will occur during the phase-to-phase process, affecting subsequent molding. In order to solve this problem, domestic and foreign material engineers have conducted a systematic and in-depth study of the theoretical mechanism of the process, and proposed a pre-aging/pre-strain treatment process. Through the pre-aging process after the solution treatment of the raw material plant, the natural aging problem in the transportation and storage of the sheet material can be reduced, so that it has better moldability in the stamping process.
The reasonable treatment of the surface of the aluminum plate is beneficial to the subsequent coating treatment. The surface treatment is mainly to treat the cold rolled state and is divided into smooth finish (MF), Electron Discharge Texture (EDT) and Electron Beam Texture (EBT) treatment.
Second, the body aluminum plate technology equipment Automotive aluminum production core technology in continuous annealing heat treatment and surface treatment, heating furnace, hot rolling mill, coiler, cold rolling mill and air-cushion continuous heat treatment furnace. Modern hot-rolling mills typically consist of a reversing bloomer and a high-speed finishing train followed by a single-stand reversible mill. The smelting, hot rolling and cold rolling processes are not significantly different from the conventional aluminum plate production process, so there are no special requirements for the corresponding equipment.
The air-cushion furnace used in the continuous annealing heat treatment process mainly includes uncoilers, degreasing tanks, drying ovens, heating zones, cooling zones, coiling machines, etc. The static and dynamic airflow in the furnace supports the strips as a mat and achieves Heating or cooling. The aluminum plate floats stably at a certain height in the furnace, and the speed of the air flow is used to ensure high-speed heat exchange with the aluminum plate. By controlling the operating speed of the aluminum plate in the furnace, the tension applied and the furnace temperature, the solution treatment process of the aluminum plate is realized.
In the heating zone of the air-cushion furnace, the accuracy of the furnace temperature of foreign high-level solution treatment can be controlled at Â±1.5Â°C, the corresponding plate temperature is Â±2Â°C, and the domestic air-cushion furnace temperature control accuracy is Â±3Â°C. At present, the equipment produced by domestic manufacturers is not yet able to meet the precision requirements for the production of automotive panels. The entire automotive panel production line equipment needs to be imported. The major foreign manufacturers of rolling mills are SMSDemag AG, which was established by the merger of SMS Schneider Maschinenfabrik (SMS) and Mannesmann demark (Demag). It is a world-wide company in the steel, aluminum and copper industry in terms of complete equipment and engineering. Leaders. Continuous air-cushion furnace manufacturers mainly for the United States Surface company.
III. Capacity planning of aluminum plate suppliers at home and abroad and future car market forecasts The overseas car aluminum plate production capacity ABS production companies have a total of 19 plants with a total production capacity of 2.46 million tons. The main distribution:
At present, the total aluminum production capacity in China is about 915 thousand tons, and its distribution is shown in Figure 6. Among them, the foreign companies Nobles, Kobe Steel and Aleris International accounted for more than one-third of the total domestic production capacity. Due to their deep production experience and industry background, it is easier than domestic manufacturers. Obtained industry certification for the automotive industry.
Most domestic auto aluminum production enterprises do not have relevant industry background and technical foundation. They are still in the imitation of foreign countries and are at a disadvantage in theoretical mechanism and technology. However, most of the domestic aluminum manufacturers have a good basis for cooperation with domestic auto makers of their own brands. They also have certain advantages in terms of price, and they have strong operability and can be tailored to the actual needs of auto manufacturers.
Whether it is from the strategic needs of the country, or the technical strength of domestic manufacturers, there is no doubt that the automotive aluminum batch application. The demand in the domestic market is also amazing. This is also the reason why foreign companies have entered the business. In order to meet the automotive lightweight demand, many alternative materials will evolve, among which aluminum is a strong opponent that can challenge steel for a long time. A large number of aluminum applications are limited by factors such as high raw material and manufacturing costs, industrial structure, recycling, and management. With the development of various technologies, such restrictions will achieve breakthroughs.
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