Abstract: Through experimental research, the optimized finish annealing process for 0.095mm thick 3102 aluminum alloy foil is determined as follows: 2h furnace gas is heated to 290°C, heat preservation is 12h, after 0.5h furnace gas is cooled to 275°C, heat preservation is 10h The foil roll is air-cooled out of the oven. Using this optimized process for finished annealing, the performance of the foil meets the requirements of air-conditioning foil, and it saves about 6h compared with the annealing process before optimization, reducing energy consumption.
The rapid development of the air-conditioning industry has increased the market demand for aluminum foil for air-conditioning. At present, domestic air-conditioning foils are mainly produced with 8011 and 3102 aluminum alloys. Due to the alloying elements contained in 3102 aluminum alloy, its brittleness is reduced, and the tendency of edge cracking is small during the rolling process. This aluminum alloy foil product has a higher yield strength and can better adapt to punching processing. It has good processing performance, and the use performance can fully meet the processing performance requirements of customers and other advantages. Therefore, 3102 aluminum alloy is favored by air conditioner aluminum foil manufacturers.
Our company has successfully developed and produced 3102-H26 aluminum alloy air conditioner foil. At present, our company has been mass production and supply to various customer groups. Due to the continuous increase in output, the annealing process has gradually become a bottleneck restricting its increase in output and reducing costs due to the longer time. Therefore, in order to meet market demand, reasonable optimization of the annealing process has become an urgent problem to be solved.
1 Test 1.1 Test materials and equipment Air conditioner The performance requirements of 3102-H26 aluminum alloy are shown in Table 1.
The test material is 3 rolls of 3102 aluminum alloy rolled foil, the material width is 1380mm, and the rolled product has a coil weight of 6.22t to 6.27t. The equipment used for the test is a 60t hot-air circulating trolley-type annealing furnace for the annealing of aluminum plates, strips and foils.
1.2 Determination of the experimental plan for the optimized annealing process The thickness of the finished 3102 aluminum alloy foil used in the test is 0.095mm, and the total rolling deformation rate is 98.60%. The tensile strength of the 3102 aluminum alloy foil in the H18 state before annealing is 248.39N/mm2. According to the accumulated actual production experience, the sample is taken from the foil coil used for the test and the annealing test is carried out in the muffle furnace. The test results are shown in the figure 1 shown.
The results of the annealing test in the muffle furnace are: the tensile strength of the sample is 146.24N/mm2 when the temperature is kept at 280°C for 4h; the tensile strength of the sample is 144.77N/mm2 when the temperature is kept at 280°C for 6h; the temperature is kept at 300°C The tensile strength of the sample was 140.37N/mm2 at 4h; the tensile strength of the sample was 140.36N/mm2 at 300°C for 6h, but at this time, the tensile sample showed a slight orange peel. Analysis believes that the annealing temperature of 280°C has met the annealing demand. The muffle furnace is a small-scale experimental annealing furnace. Considering its slightly poorer furnace insulation and its difference with large-scale annealing furnaces for production, in order to prevent excessive annealing of aluminum foil, the annealing temperature is set to 275° when designing the industrial test plan. C. The design plan of industrial experiment to optimize the annealing process is shown in Table 3.
2 Industrial annealing test results and analysis In the industrial annealing test, the furnace gas temperature was set to rise to 290°C within 2h, and the furnace material temperature reached 260°C on average when the furnace gas temperature reached 290°C and kept for 12h; After the furnace gas temperature is reduced to 275°C and kept for 3 hours, the material temperature reaches an average of 274°C. After keeping the temperature for 8 hours, the furnace is air-cooled. The temperature measurement curve is shown in Figure 2.
From the temperature measurement curve in Figure 2, there are slight differences in the heating process of the foil coils at different positions in the furnace, but as the annealing time increases, the temperature of the three foil coils gradually tends to be the same. The main reason for this phenomenon is that the axial flow fan at the top of the annealing furnace works due to the way of radial heat dissipation. The hot air flow and the foil roll placed horizontally on the rack form convective heat exchange in the radial direction. This is to a certain extent. The above will affect the heat exchange efficiency of the foil, so when installing the furnace, try to ensure the distance between the foil rolls and the position of the foil rolls, and try to avoid uneven heat exchange leading to temperature deviations. In order to reduce the above-mentioned adverse effects, measures such as controlling the amount of furnace installed and appropriately increasing the holding time are generally adopted in production.
After annealing, the foil performance test results are shown in Table 4. Its performance meets the expected requirements, and the 3102-H26 aluminum alloy foil produced meets the user’s requirements during the processing of the two air conditioner fins.
The above-mentioned annealing process schematic diagram is shown in Figure 3. The final annealing temperature CD section is the key stage of the annealing process, which determines whether the performance of the product can reach the required level. Because aluminum alloy foil has a large total processing deformation rate, and the distortion energy stored in the metal is large, the recovery and recrystallization speed of aluminum alloy foil during the annealing process will be relatively fast, and the recrystallization and deformation structure must be controlled. In relative proportion, in this experiment, the temperature measurement method is used to effectively control the heating process of the annealing treatment of aluminum alloy foil, accurately grasp the temperature transition point of the high temperature stage, avoid excessive recrystallization process, and ensure the holding time at the final annealing temperature . It has been verified that the annealing process system meets the actual production situation, meets the requirements of aluminum alloy foil performance, improves the annealing efficiency, and alleviates the bottleneck problem of the annealing process.
3 Conclusion Under the condition that the company’s original rolling and other processes remain unchanged, the optimal annealing process for 3102-H26 aluminum alloy foil optimization is: 2h furnace gas temperature rise to 290°C, heat preservation 12h, 0.5h furnace gas temperature drop to 275° C, the foil rolls out of the furnace and air-cooled after holding for 10 hours. The annealing process not only meets the performance requirements of air conditioning foils, but also shortens the annealing cycle, reduces energy consumption, and saves costs.
This article is translated from the light alloy processing technology Li Gaolin Tangwei, if you are interested in our company’s aluminum foil products, please feel free to contact Jack Han [email protected]