Over-head position welding must pay attention to maintain the correct operation posture, the welding point is not in the person is above, should be the top of the front, and the weld bias to the right side of the operator, as shown in the figure, overhead welding electrode clamping mode is the same as the vertical welding.
Adopt small diameter electrode and small current welding. Generally, the welding current of vertical welding is between the welding current of horizontal welding and the welding current of vertical welding.
Adopt short arc welding to facilitate droplet transition.
Maintain proper electrode Angle and correct rod handling mode as shown in the following figure.
For butt welding with no groove, the straight line strip should be used when the gap is small, and the reciprocating straight line strip should be used when the gap is large.
When the butt butt welding of groove is multi-layer welding, the straight line or straight line transport mode is used for the first layer of weld according to the size of groove gap.The rest of the layers are in crescent or zigzag mode.
Straight - line strip should be used for multi-layer and multi-pass welding.
For the T-joint with small welding foot size, the single-layer welding is adopted, and the straight-line running mode is selected.When the welding foot size is large, multi-layer welding or multi-layer welding is used.The first layer should choose straight line strip, the rest of the layers can use oblique ring or triangular strip mode.
When the temperature of the molten pool is too high, the arc can be slightly raised to lower the temperature of the molten pool slightly.
Due to the gravity of welding gun and cable, the operator is prone to instability of the gun, so sometimes it is necessary to hold the gun in both hands for welding.
When using the oblique circle strip, you should consciously let the electrode head point to the upper plate first, so that the droplet will fuse with the upper plate first. Due to the action of the strip, part of the liquid metal will naturally be dragged to the steel plate of the facade, so that the two times can get uniform fusion.
The short arc welding of 0.5~1mm should be maintained when the straight line is transported. Do not drag the electrode head along the weld to prevent the occurrence of narrow and convex weld.Maintain correct electrode Angle and uniform welding speed, keep the arc short, and the upward feed speed should be consistent with the burn rate of the electrode.
When the temperature is high, the surface of the weld pool will bulge or protrude, and when it is serious, the weld nodule will appear. The solution is to accelerate the forward swing speed and shorten the stay time on both sides, and reduce the welding current when necessary.
Multi-pass welding in addition to the bottom of the careful slag cleaning, cover the surface of each do not clear slag, can be welded in the order shown in the following figure, after the center of the welding rod pointing to the front of a weld 1/3 or 1/2 edge.The welding rod Angle must be correct, the speed should be uniform, and the arc should be short.
Start welding and continue in the preheating process is easy to appear the phenomenon of molten slag and metal liquid mixed together, then the Angle between the electrode and the upper plate should be reduced to increase the arc blowing force, never extinguish the arc, if the start welding has been too high or welding tumor, it should be cut off with arc.
2021-01-28 
