[China Aluminum Industry Net] One of the performances of pure aluminum aluminum tubes in industrial use is the industrialization of the rolling wings. Such products are widely used from common industrial plant heating, large-scale cooling and heat exchange equipment, and high-performance radiators for automobiles. Divided from its attached pipes are generally divided into steel pipes and copper pipes. The method of rolling is that the steel pipe or copper pipe is passed through a pure aluminum pipe and is formed by a fin rolling mill after determining the corresponding rolling parameters. In this process, the height of the fins, and the roundness and cracking of the fins, in addition to the wall thickness and fit clearance of the pipe design, the performance of the pure aluminum pipe itself and the corresponding quality conditions are the main It's up.
The following takes the 1060H112 as an example to illustrate the quality control of pure aluminum pipes from several aspects such as material, extrusion, packaging, storage and transportation.
1. Material
The aluminum purity of the aluminum-aluminum tube is very important. Although it is clearly identified as a 1060 alloy in the customer's contract, the fin cracking defect is easily caused by the impurity content in the alloy composition in GB/T3190. Therefore, in the actual composition control, the company has strictly controlled the alloy composition. The specific comparison is shown in Table 1.
Table I
Grade
chemical composition/%
Si
Fe
Cu
Mn
Mg
Cr
Ni
Zn
Ti
other
Al
single
total
1060
≤0.25
≤0.35
≤ 0.05
≤0.03
≤0.03
-
-
≤ 0.05
V: 0.05
≤0.03
≤0.03
-
99.60
Internal control
≤0.15
≤0.12
≤0.04
≤0.01
≤0.01
≤0.01
≤0.01
≤0.04
V: 0.05
≤ 0.02
≤ 0.02
0.05
99.70
1070
≤0.20
≤0.25
≤0.04
≤0.03
≤0.03
-
-
≤0.04
V: 0.05
≤0.03
≤0.03
-
99.70
As can be seen from Table 1, the composition of the control is quite strict, from the composition of the index value can be seen close to the 1070 alloy, but the individual components than the 1070 alloy is even more stringent, originally 1070 alloy has a very good height However, the purity of the components should be taken into consideration for the fin thickness and cracking. In addition, the purity of aluminum is also a prerequisite for good welding and rolling elongation.
2. Extrusion
Extrusion The performance of pure aluminum pipes, whether it is the height, the rolling elongation, or the rolling yield, is determined in terms of impact. The effect of extrusion on pure aluminum tubes is reflected in the following aspects:
2.1 Mold
The common non-rolling aluminum tube extrusion die design does not need to consider the problem of full welding, under normal inspection conditions, the appearance of the naked eye to observe no obvious weld line, no obvious cracking, in this condition, its internal Pressure capacity can generally be 1.5 times higher than the index value. However, for pure aluminum tubes, the requirement of welding is very important. At this time, the design of common molds cannot meet the requirements. Compared with ordinary molds, it is necessary to work hard at full welding, when the mold is designed. Sufficient sink bridge treatment should be made. In this state, there is a difference of 10-12 mm from the normal mold. This has a profound effect on the cracking degree of the rear wing fins of pure aluminum tubes.
2.2 Warming
Normal aluminum rod heating is generally between 450-490 °C, insulation 2.5 hours or so, but for aluminum rod heating aluminum rod is not applicable. After a long-term experiment, the author found out that the groping and trial production had been found to be more reasonable. The heating temperature was controlled between 500 and 530°C. It was more reasonable and the insulation was maintained for more than 2.5 hours. This will ensure adequate welding, lift height and elongation.