Little knowledge about carbon arc gouging

1、 Principle and characteristics of carbon arc gouging

The characteristics of carbon arc gas generation are:

1. Carbon arc air gouging can increase productivity by 10 times compared with air shovel, and has more advantages in overhead or vertical position.

2. Compared with the pneumatic shovel, the noise is small, the labor intensity is reduced, and it can be mechanized.

3. Small defects are easy to be found when carbon arc gas welding root is carried out for back cover welding, and the disadvantage that the pneumatic shovel cannot be used due to its narrow position can be overcome.

4. Carbon arc gouging also has some disadvantages, such as smoke, high noise, dust pollution, arc radiation, etc.

Carbon arc gouging is widely used to clean the weld root, remove the weld defects, open the welding groove (especially the U-shaped groove), clean the rough edges, pouring risers and defects of castings, and cut various metal materials that cannot be cut with oxygen acetylene flame.

2、 Carbon arc gouging equipment

1. The carbon arc gas generating equipment is composed of power supply, air gouging gun, carbon rod, cable gas pipe and air compressor.

2. Carbon arc gouging generally adopts direct and current power supply with steep drop external characteristics. Due to large current and long continuous working time, arc welding rectifier and arc welding generator with high power shall be selected.

3. The tool of carbon arc gouging is carbon arc air gun, which has two types: side air supply air gun and circumferential air supply air gun.

4. The electrode material of carbon arc air gouging generally adopts copper plated solid carbon rod, and its section shape has circular and flat shape, which is selected according to the planing requirements. Among them, circular carbon rod is the most widely used. - Welcome your inquiry to - XINGSHI Carbon electrode 

3、 Carbon arc gouging process

The process parameters of carbon arc gouging mainly include power polarity, current and carbon rod diameter, cutting speed, compressed air pressure, extension length of carbon rod, inclination angle between carbon rod and workpiece, arc length, etc.

1. Polarity

Carbon arc air gouging generally adopts DC reverse polarity (positive polarity is adopted for cast iron, copper and copper alloy), so that the gouging process is stable and the gouging groove is smooth.

2. Carbon rod diameter and current

The diameter of carbon rod is selected according to the thickness and current of the planed metal. The thicker the planed metal is, the larger the diameter of carbon rod is. The planing current is directly proportional to the diameter of the carbon rod. The diameter of the carbon rod is also related to the groove width. The larger the diameter of the carbon rod, the wider the groove. Generally, the carbon rod should be 2-4mm smaller than the groove.

3. Planing speed

The planing speed has a certain influence on the groove size and surface quality. If the planing speed is too fast, the carbon rod will collide with the metal, making the carbon rod stick to the planing groove, resulting in carbon inclusion defects. The planing speed increases and the planing depth decreases. Generally, the planing speed is 0.5 ~ 1.2 m / min.

4. Pressure of compressed air

The pressure of compressed air is high, which can quickly blow away the liquid metal and make the carbon arc gouging smoothly. Generally, the pressure of compressed air is 0.4-0.6mpa. The moisture in compressed air shall be properly controlled. Excessive moisture and oil will deteriorate the surface quality of gouging.

5. Arc length

The arc is too long, resulting in unstable operation and even arc extinguishing. Therefore, it is required to keep a short arc as far as possible during operation, which can improve productivity and improve the utilization rate of carbon rods. However, the arc is too short and it is easy to cause "carbon inclusion" defects. Therefore, the length of carbon arc gouging arc is generally 1 ~ 2 mm.

6. Inclination of carbon rod

The included angle between the carbon rod and the planer along the direction of the planer is called the inclination of the carbon rod. The dip angle affects the depth of the groove. With the increase of the dip angle, the groove depth increases, and the dip angle of the carbon rod is generally 25 ° ~ 45 °.

7. Extension length of carbon rod the length of carbon rod from the conducting nozzle to the arc end is the extension length. The longer the extension length of the carbon rod, the insufficient wind force of compressed air to the molten pool will not be able to successfully blow away the molten metal. At the same time, the longer the extension length, the resistance of the carbon rod will increase and the burning loss will be faster. However, too short extension length will cause inconvenient operation. Generally, the extension length of carbon rod should be 80 ~ 100 mm.