First, strike the arc.

The so-called arc initiation is the process of igniting the welding arc. There are two kinds of arc striking methods:

(1) rowing method: first, aim the covered electrode at the weldment, lightly cut the covered electrode on the surface of the weldment like a match, ignite the arc, and then quickly lift the covered electrode for 2 ~ 4 mm to keep the combustion stable.

(2) Direct arc initiation method: butt weld the electrode tip of the coating, then bend the wrist downward, so that the coating electrode can be lifted 2 ~ 4 mm quickly after slight contact with the weldment, and hold the electrode holder by the wrist to make the arc burn stably. This method will not scratch the surface of the weldment and is commonly used in production. In order to facilitate arcing, the cored wire should be exposed at the end of covered electrode. If there is a coated sleeve at the end of covered electrode, it can be clipped off with the welder's gloves. If there is adhesion during arc striking, it can be removed by swinging the covered electrode left and right.

Second, shipment.

After arc striking, covered electrode generally has three basic actions, namely, gradually feeding in the direction of the molten pool, gradually moving along the welding direction, and swinging laterally.

(1) covered electrode gradually feeds into the molten pool, which means that the molten metal in covered electrode transits to the molten pool, and the covered electrode becomes shorter. In order to keep a certain arc length, covered electrode must be sent into the molten pool, and keep the same feeding speed as covered electrode. If the feed speed is slow, the arc will be too long or broken. If the feed speed is fast, the coated covered electrode will not melt and stick to the weldment.

(2) The covered electrode moves along the welding direction, gradually forming a weld bead. If covered electrode moves forward too fast, the weld will become narrow and the fusion will be poor. If covered electrode moves forward too slowly, the weld will be too high and too wide, and the thin weldment will burn through.

(3) covered electrode's lateral swing is to obtain a weld with a certain width. The swing range depends on the thickness of weldment, groove form, weld height and covered electrode diameter. The thicker the weldment, the greater the swing amplitude. The swing of the V-shaped groove is wider than that of the V-shaped groove, and the swing of the outer layer is wider than that of the inner layer.

The above three actions cannot be separated mechanically, but must be coordinated and unified to get a beautiful and qualified weld.

Third, the weld connection

Because a complete weld is limited by the length of covered electrode, it needs to be welded by several covered electrode, which leads to the problem of weld connection. In order to ensure the quality of weld connection and make weld connection uniform, welders are required to choose appropriate methods and master them skillfully. There are four weld bead connection methods.

First, the joint method is to strike an arc about 10mm before the crater of the previous weld bead, lengthen the arc and move it to 2/3 of the original crater, reduce the arc, covered electrode slightly rotates, and then move forward into normal welding after the crater is filled.

Second, the starting point of the first pass is required to be slightly lower. When connecting, the arc should be started slightly in front of the starting point of the first weld bead, and the arc should be slightly elongated. Move the arc to the beginning of the first pass, lower the arc and cover the fused end to move forward into normal welding.

Thirdly, the back weld bead starts from the other end of the joint and is welded to the end of the front weld bead. The welding speed is slightly slower to fill the arc pit of the weld bead, and then the arc is extinguished slightly forward at a faster welding speed. Fourthly, the end of the back weld bead is connected with the beginning of the first weld bead, and then the beginning of the first weld bead is repeatedly melted by the high temperature at the end, and the arc striking is completed after the weld bead is leveled.

Fourth, the station, welding posture

As the saying goes, "there is a standing posture when standing, and a sitting posture when sitting." Of course, welders should also have correct standing posture and welding posture when operating. Correct standing posture and welding posture can not only help the welder to complete the welding task with half the effort, but also effectively avoid the welder's scald and protect all joints, lumbar vertebrae and cervical vertebrae from injury. The correct position generally requires the welder to choose a reasonable position according to the spatial position of the weld. When standing, we should consider the effective functions of various parts of the body, such as the distance between the glasses and the weld, whether it will affect the wrist swing and so on. Welding posture is also important. Correct welding posture means that the welder gives full play to all parts during welding, with low physical consumption, good vision and convenient operation. This requires welders to abandon the mentality of "making do" from subjective and objective factors, take it seriously subjectively, analyze it carefully and try again and again. Over time, the experience of correct welding posture will become more and more abundant, and objectively, we should actively eliminate the factors that may cause incorrect welding posture.

Five, the weld is beautiful

The welder controls the welding pool according to the process card and reasonable skills, and realizes the weld with beautiful appearance and excellent quality. Welders are required to fully understand the temperature field of molten pool and the principle of arc transition. Generally, the temperature of the welding pool is basically the highest in the center of the pool, and the molten iron has good fluidity, and the temperatures on both sides and the back surface gradually decrease. According to this principle, we can analyze that the arc pool is also moving. When moving from 1-2-3-4-N, because the arc frequently passes through the center of the molten pool, the heat in the middle of the molten pool is the highest, so the molten iron in the middle is thinner. If 1-2-3-4-N moves at a uniform speed, the middle of the weld will protrude, but the two sides are not full, resulting in defects such as excessive weld residual height and undercut on both sides. According to this principle, when welding by hand, the welder must avoid the uniform motion of the arc in the weld. Generally, it is required to stop at both sides of the weld and make a quick transition in the middle to balance the heat of the molten pool and control the weld quality and beautiful appearance.