Four vertical welding methods are shown today. Vertical welding needs to build a base platform by spot welding on base metal. Then it can be welded by zigzag method, crescent method, anti-crescent method and 8-character method.
Next, let’s briefly analyse the skills of these four ways to transport electrodes.
Sawtooth traveling strip method: When using this traveling strip method to weld, the end of the welding strip oscillates continuously and moves forward, and stops for a moment on both sides. The purpose of oscillation is to control the flow of molten metal and obtain the necessary weld width in order to obtain better weld forming.
Positive and inverse crescent rod method: When using this method to weld, the end of the rod oscillates left and right along the welding direction. The swing speed depends on the position of the weld, the form of the joint, the width of the weld and the value of the welding current. At the same time, it is necessary to make a short stay on both sides of the joint, in order to make the weld edge have enough penetration and prevent undercutting. The advantages of this method are that the metal melts well, the heat preservation time is long, the gas is easy to precipitate, the slag is easy to float on the surface of the weld, the quality of the weld is high, but the residual height of the weld is high.
Octagonal bar method: When welding with this method, the end of the electrode moves in octagonal shape and moves forward continuously, as shown in Fig. I. The point of this method is to ensure that the edge of the weld is fully heated, melted uniformly and penetrated. It is suitable for butt welds with grooves on thick plates. For example, when welding two welds with different thickness, the electrode should stay for a while on one side of the thickness to ensure uniform heating and full melting, so as to make the weld shape well.