What is Gas Gouging?
Carbon arc gouging is to use the high-temperature current generated between the carbon electrode and the metal to locally heat the metal to a molten state, and at the same time use the high-speed air flow of compressed air to blow away these molten metals, thereby achieving planing and cutting of the metal base A processing method.
Gouging
- Arc gouging
- Carbon arc gouging is to use the high-temperature current generated between the carbon electrode and the metal to locally heat the metal to a molten state, and at the same time use the high-speed air flow of compressed air to blow away these molten metals, thereby achieving planing and cutting of the metal base A processing method.
- 1. Clean the roots.
- Use
- Carbon rod specifications and applicable current (Table 1)
- The current has a great influence on the size of the planing groove. When the current increases, the width of the planing groove increases and the depth increases more. Taking a large current can increase the planing speed and obtain a smoother planing groove. However, when the current is too large, the carbon rod head is prone to redness, and the copper plating layer is liable to fall off. Under normal current, the length of redness of the carbon rod is 25mm. If the current is small, the phenomenon of carbon sticking is easy to occur. In actual production, you can refer to Table 1 to select the current.
- Table 1 Carbon rod specifications and applicable current
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- Planing speed
- The cutting speed has a certain effect on the size of the groove and the surface quality. Too fast speed will cause the carbon rods to collide with the metal, which will cause the carbon to stick to the top of the trough and form a "clamping" defect. On the contrary, too slow and prone to "slag sticking" problems. Usually, the planing speed is 0.5-1.2 m / min.
- Arc length
- When gouging, the arc length can cause arc instability and even arcing. Generally, short arc should be used to improve production efficiency and carbon rod utilization. Generally, the arc length should be 1-2 mm.
- Carbon stick extended length
- The length of the carbon rod from the jaw to the arc end is the extended length (as shown in Figure 1). The longer the extended length, the farther the jaw is from the arc, the lower the blowing force of compressed air to the molten pool, and the molten metal cannot Blow off smoothly; on the other hand, the longer the extended length, the greater the resistance of the carbon rod, and the faster the burning. In operation, the suitable extension length of the carbon rod is 80-100 mm, and it needs to be adjusted when it burns to 20-30 mm.
- Carbon rod inclination
- The angle between the carbon rod and the workpiece along the groove direction is called the carbon rod inclination angle, and the depth of the groove is related to the inclination angle. Increasing the inclination angle increases the depth of the gouging groove; otherwise, decreasing the inclination angle decreases the depth of the gouging groove. The inclination of carbon rods is generally 25 ° --45 °
- 1. Prepare the workpiece
- Before planing, check whether the polarity of the power supply is correct (generally, the planing gun is connected to the positive electrode, and the workpiece is connected to the negative electrode). Check whether the cables and air pipes are connected properly. And choose the diameter of the carbon rod and adjust the current according to the thickness of the workpiece and the width of the groove. Adjust the carbon rod extension length to 80 <? Xml: namespace prefix = st1 ns = "urn: schemas-microsoft-com: office: smarttags" /> 100mm. Check the compressed air line and adjust the pressure, adjust the air outlet and align it with the trough.
- 2. Pilot arc
- When initiating an arc, the gas valve should be opened slowly, and then the arc should be ignited, otherwise "carbon trapping" and carbon rods will be easily burned. When the arc is ignited, it should not be pulled too long, so as not to extinguish.
- 3.Planing
- Because the temperature of the steel plate is low at the beginning of planing, it cannot be melted quickly. When the arc is ignited, the planing speed should be slower; When the steel plate is melted and blown away by compressed air, the planing speed can be appropriately increased.
- During the planing process, the carbon rods should not oscillate laterally and reciprocate back and forth, but can only move linearly along the planing direction.
- The inclination angle of the carbon rod is determined by the groove depth requirement, and the inclination angle can be 25 ° --45.
- When planing, the movement of the hand should be stable, and the center line of the carbon rod should be coincident with the center line of the planing groove. Otherwise, it is easy to cause the shape of the trough to be asymmetric.
- When gouging in the vertical position, it should be moved from top to bottom so that the welding slag flows out.
- Keep a uniform planing speed. When planing, a uniform and crisp "hiss, hiss" sound indicates that the arc is stable and a smooth and even planing groove can be obtained. When each section of the trough is connected, an arc should be induced on the arc pit to prevent touching the trough or generating serious dents.
- When the planing is finished, cut off the arc first, and then close the gas valve after a few seconds to cool the carbon rod.
- After planing the trough, remove the iron slag, burrs and scale on the planing trough and its edges. Use a wire brush to remove the carbon ash and "copper spots" in the planing trough. According to the requirements of the planing groove, check whether the root of the weld is completely planed and whether the defect is completely removed.
- 4.Planing defects during welding repair
- After the weld is inspected, it is found that there are superstandard defects, which can be removed by carbon arc gouging. Plan according to the marks of the defect positions made by the inspectors on the welding process. Plan the layers one by one during the planing process, and each layer should not be too thick. When a defect is found, gently plan further down one or two layers until the defect is completely planed away.