Brushed aluminum plate in the actual use of the process, is the need to weld before they can be used, but the welding steps believe that many people are not very well understood, GNEE the following for you to briefly introduce:
First, pre-welding preparation: the choice of chemical or mechanical methods, strict cleaning of the weld bevel on both sides of the appearance of the oxide film. Chemical cleaning is the use of alkali or acid cleaning the appearance of the workpiece, the approach can remove the oxide film, but also remove oil, the specific process is as follows: volume fraction of 6% ~ 10% of sodium hydroxide solution, soaked at about 70 ℃ for 0.5 minutes → wash → volume fraction of 15% of nitric acid at room temperature for 1 minute to neutralize the treatment → wash → warm water wash → dry. After washing, the appearance of the aluminum alloy is silver-white without luster. Clean up immediately after welding, if placed more than 4h, should be re-cleaned.
Second, to determine the installation gap and positioning welding distance welding process, aluminum plate thermal expansion, resulting in weld bevel gap reduction, pre-welding installation gap if left too small, the welding process will cause the two boards of the bevel overlap, adding weld plate surface unevenness and deformation; on the contrary, the installation gap is too large, it is difficult to weld, and there is a possibility of burn-through. Appropriate positioning welding distance can ensure that the required positioning welding gap, therefore, select the appropriate installation gap and positioning welding distance, is to reduce the deformation of an effective way.
Third, the selection of welding equipment on the market now more welding product varieties, it is generally advisable to choose AC tungsten argon arc welding (i.e., TIG welding). It is under the protection of argon gas, the use of tungsten electrode and workpiece asked to occur in the arc heat melting base material and filler wire of a welding method. The welding machine operation, because the polarity of the AC current is in the cycle of change, in each cycle half-wave DC positive connection, half-wave DC reverse connection. Positively connected half-wave during the tungsten electrode can emit enough electrons without overheating, which is conducive to the stability of the arc. Reverse half-wave period of the workpiece surface generated during the oxide film is easy to be cleaned up and get the appearance of bright and beautiful, forming an outstanding weld.
Fourth, the selection of welding wire generally choose 301 pure aluminum wire and 311 aluminum silicon wire. Selection of welding methods and parameters generally to the left welding method, the torch and the workpiece into a 60 ° angle. Welding thickness of 15mm or more, to the right welding method, the torch and the workpiece into a 90 ° angle. Welding wall thickness of more than 3mm, open V-shaped bevel, the angle of 60 ° ~ 70 °, the gap shall not be greater than 1mm, to complete the multi-layer welding. Wall thickness of 1.5mm or less, no bevel, no gap, no filler wire. Welding fixed pipe butt joints, when the pipe diameter of 200mm, wall thickness of 6mm, should be selected for the diameter of 3~4mm tungsten electrode, 220~240A welding current, diameter of 4mm filler wire, to 1~2 layers of welding.
