Selection Of Welding Process

Pipeline automatic welding wire feeding method:

The smoothness of wire feeding directly affects the welding quality. Wire feeding methods can be simply divided into two ways: wire drawing and wire pushing. When the wire is drawn, the welding gun is closer to the installation position of the wire feeder. During the welding process, the resistance of the welding wire after leaving the wire feeder is small, so the wire feeding process can be ensured smoothly, but the wire feeder and the welding wire reel must be installed in the welding head. The upper part increases the weight of the welding head, which makes manual assembly and disassembly difficult, and the increase in weight can easily cause the welding head to walk unevenly. The use of a small welding wire with a diameter of 0.8mm or 1.0mm (weight is about 5kg) reduces the weight and load of the welding head and makes the welding process easy to control, but it has a certain impact on the welding efficiency. When the wire push method is used, the wire feeding mechanism is installed outside the welding head, which reduces the size and weight of the welding head. You can use a high-power wire feeder and a large plate of welding wire with a diameter of 1.2mm (weight about 15kg). Thereby improving welding efficiency. However, because the wire feeder is far away from the welding gun when pushing the wire, there must be a wire feeding hose connected between them. When the welding wire is continuously pushed to the welding gun nozzle, the friction resistance of the welding wire is relatively large. The curvature of the wire feeding hose has a certain effect on the smoothness of the wire feeding. In severe cases, the wire feeding will not be smooth. Therefore, the above factors must be fully considered when using the wire pushing.

Selection of welding process:
At present, in addition to manual welding, automatic submerged arc welding and gas-shielded welding are commonly used in pipeline welding.
Automatic submerged arc welding has the characteristics of good weld formation, high welding efficiency, and low welding cost. For pipeline construction, automatic submerged arc welding can be used for double pipe joint welding, referred to as "two to one", that is, the welding torch is fixed at a certain position, the tube rotates. Obviously, it is impossible to rotate the pipe when welding long-distance pipes, so "two-by-one" can only be used for pipe prefabrication. If the submerged arc welding process is used for all-position automatic welding of the pipeline, the welding device is equipped with a flux placement, support, and recovery mechanism, which makes the structure of the welding device more complicated, which brings inconvenience to operation. The load of the trolley affects the stability of the head. Submerged arc welding generally uses thick wire and high current welding methods. For all-position automatic welding, welding defects such as droplet and flow may occur due to the high deposition rate, which affects the formation and quality of the weld. Therefore, the submerged arc welding is more difficult to realize automatic welding in all positions welding of pipelines.