10 major welding technology must know knowledge points
Release time:
2023-08-01
The process of igniting and producing a stable arc is called arc striking. There are two kinds of arc striking method: scratch arc striking method and direct arc striking method.
igniting and producing a stable arc is called arc initiation. There are two kinds of arc striking method: scratch arc striking method and direct arc striking method.
scratch arc ignition method, align the end of the welding rod with the arc ignition position, and then gently scratch the welding rod on the surface of the welding piece with wrist force like a match, scratch the distance of 10-20mm, and lift the welding rod 3-3mm.
Direct arc striking method. First, align the welding rod with the welding part to be welded and gently touch it, and lift the welding rod 2-3mm in time to ignite.
When starting the arc, the electrode should be lifted quickly, otherwise it will easily stick to the workpiece. If sticking occurs, the welding rod can be pulled apart after shaking left and right. If it cannot be opened, the welding tongs shall be loosened, the welding circuit shall be cut off, and the welding parts shall be treated after they are slightly cold.
1. The following points should be paid attention to when starting the arc:
(1) After starting the arc, the arc length should not exceed the diameter of the electrode. Do not apply too much force during arc ignition to prevent the coating skin at the arc ignition end from cracking or even falling off, which will affect arc ignition and welding.
(2) Do not ignite on the weldment at will when striking the arc, especially high-strength steel, low-temperature steel, and stainless steel. This is because the arc scratch site is likely to cause hardening or micro-cracking, stainless steel will reduce corrosion resistance.
(3) When starting the arc, if the welding rod and the welding part are connected together and cannot be removed by shaking, the welding tongs should be removed immediately. After the welding rod is cooled, it is easy to remove it.
2. What is spot fixation before welding?
In order to fix the relative position of the two weldments, tack welding (usually called spot fixation) should be carried out at both ends of the workpiece before welding.
# Clean up the slag after fixing at 20 o'clock. If the weldment is longer, it can be every 200-300mm or so, point fixed a solder joint.3. What is positive connection? What is reverse connection?During the welding process, the two poles of the arc welding machine are respectively connected to the welding rod and the weldment to form a complete welding circuit. For DC welders, one is very positive and the other is very negative. When the weldment is connected to the positive pole and the welding tongs (welding rods) are connected to the negative pole, it is called the positive connection method (referred to as the positive connection), otherwise it is called the reverse connection method (referred to as the reverse connection). For AC welding machine, since the polarity of the power supply is alternating, there is no problem of positive and negative connection.4. How to start when welding rod arc welding?Welding Technology The beginning of the weld is the beginning part of the weld. Due to the low temperature of the weldment, the temperature of the weldment cannot be quickly increased after arc ignition. Under normal circumstances, the residual height of this part of the weld is slightly higher, the penetration depth is shallow, and even poor fusion and slag inclusion may occur. Therefore, the arc should be slightly elongated after arc ignition to preheat the workpiece, and then the pressure arc should be welded normally. Flat welding and alkaline welding rods mostly use reflow welding method, starting the arc from 10mm away from the initial welding point, reflow to the starting point, gradually depressing the arc, while the welding rod swings slightly to reach the required weld width, and then normal welding is carried out.Latest News
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