Copper is a kind of metal with excellent conductivity, thermal conductivity, corrosion resistance and ductility, and its strength performance is also good. Generally speaking, red copper is copper, which is tough, soft and malleable. It has a rose red metallic luster. After the oxide film is formed on the surface, it turns purple. Therefore, the name of red copper is derived. The welding methods of red copper include gas welding, electrode arc welding, manual argon arc welding and manual carbon arc welding. Next, the hook net small knitting with you to understand, each welding method needs to pay attention to the matters.
Gas welding of red copper
Butt joint is the most commonly used joint method for gas welding of red copper, while lap joint and T-joint should be used less. There are two kinds of welding wire for gas welding, one is welding wire containing deoxidizing elements, such as wire 201 and wire 202, and the other is common copper wire or base metal cutting strip. Neutral flame should be used in red copper gas welding, and gas flux 301 should be used as flux.
Electrode arc welding of red copper
When using arc welding method to weld copper workpiece, if the thickness of welding piece is greater than 4 mm, preheating treatment must be carried out. The preheating temperature is generally between 400 and 500 ℃. During welding, copper 107 electrode should be used, and DC reverse connection should be used for power supply. The short arc is used in the arc, and the moving mode of the welding rod should be reciprocating linear motion, which can improve the forming effect of the welding seam, and should not swing horizontally. For the long weld, the step back welding method should be adopted, and the welding speed should be as fast as possible. For multi-layer welding, the slag on the surface of the previous layer must be completely removed before welding a new layer.
In addition, arc welding will produce a lot of copper vapor, so it must be carried out in a well ventilated place to avoid copper poisoning. After welding, the flat hammer should be used to knock the weld to relieve the stress and improve the quality of the weld.
Manual argon arc welding of red copper
In manual argon arc welding of red copper, the welding wire used is the same as gas welding, which is also wire 201 and wire 202. In addition, red copper wire, such as T2, can be used. Before manual argon arc welding, mechanical cleaning method or chemical cleaning method must be used to thoroughly clean the impurities such as oxide film and oil stain on the welding edge and welding wire surface. If it is not cleaned, it will form porosity, slag inclusion and other defects in the welding joint.
For butt joint plates with different thickness, different groove should be selected. When the thickness of butt joint plate is less than 3 mm, there is no need to make groove; if the thickness of joint plate is greater than 3 mm but less than 10 mm, V-shaped groove should be opened, and the angle of groove should be 60 to 70 degrees; if the thickness of joint plate is greater than 10 mm, it should be provided with “X” groove, and the angle of groove is also 60 to 70 degrees. In order to avoid the lack of penetration, the groove generally does not leave a blunt edge. According to the thickness of the plate and the size of the groove, the assembly gap of butt joint should be selected between 0.5 mm and 1.5 mm.
The direct current positive connection is adopted for the red copper machining manual argon arc welding power source, that is, the tungsten electrode is connected to the negative pole of the power supply. In order to eliminate the blowhole defect, ensure the weld root penetration and have reliable fusion, the weldment must be preheated before welding, and the welding speed should be increased and the consumption of argon gas should be reduced. When the plate thickness is less than 3 mm, the preheating temperature is between 150 ℃ and 300 ℃; when the plate thickness is greater than 3 mm, the preheating temperature should be increased to between 350 ℃ and 500 ℃. Otherwise, the mechanical properties of the joint can not be lower than the upper limit.
Manual carbon arc welding of red copper
The electrode used in manual carbon arc welding of red copper is carbon electrode or graphite electrode. The welding wires used in carbon arc welding are wire 201 and wire 202, the same as gas welding and manual argon arc welding. The base metal can also be used for cutting. The flux used is the same as that for gas welding, such as gas flux 301, etc.