[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. Its rolling performance and the corresponding quality conditions have a major influence on it.
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.
Materials
The purity of pure aluminum is very important. Although it is clearly identified as a 1060 alloy in the customer's contract, the aluminum fin cracking defects are likely to be caused by the impurity content in the alloy components in GB/T3190. Therefore, in the actual composition control, the company strictly controls the aluminum alloy components. The specific comparisons are 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
The standard value can be seen close to the 1070 alloy, but the individual components are even stricter than the 1070 alloy. The original 1070 alloy already has a good height, but the purity of the components should be considered for the fin thickness and cracking problems. Now. 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 extrusion die design of ordinary non-rolled aluminum tube does not need to consider the problem of full welding. Under the normal inspection conditions, the appearance is visually observable with no visible lines, no obvious cracking, and under such conditions, the internal pressure capacity Generally, it is 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 performed. 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.
2.3 Cooling
For the required H112 state, no full air cooling is required as long as the aluminum tube does not burn the cooling bed and does not affect the subsequent straightening temperature.
2.4 Straightening
Due to the material and temperature, the ratio of straightening stretch to tube length for pure aluminum tubes is between 30:8400.
2.5 Sawing
The pure aluminum tube has strict requirements on the length of the head at both ends when sawing. Experience and calculations have proved that it is very suitable to remove the material head with a length of ≥ 1.8m.
.package
The method of packing and stacking is very important. After a lot of experiments, the author has proved that 9 packages per package are more suitable, and the “product†shape is used for stacking. Due to the mechanical effect, it is beneficial to avoid flattening the external force of the tube. Wrapping wrapping paper outside requires compactness to avoid loose friction during transportation between aluminum tubes.
4. Storage and transportation
Due to the special circumstances of the aluminum pipe, its material and hardness, the reasons for the cross-section, but also consider the length of the case, pure aluminum pipe is not suitable for long-distance transportation, because it is very easy to cause bending scratches, so for pure aluminum The custody of the tube is based on the principle of safekeeping. At the same time, it is equipped with a special vehicle for loading and unloading problems: A 9-meter-long pallet is manufactured. The surface of the panel is covered with rubber to prevent the aluminum tube from being scratched, and at the same time, from being bent.