The gas cutting process of metal is a continuous process of preheating, combustion and slag blowing, and its essence is the process of metal burning in pure oxygen, not melting. Use preheating flame to heat the starting point (the hyperbaric oxygen valve is closed at this time), and the preheating time depends on the metal temperature until the surface of the workpiece is close to melting (the surface is orange). Then gently open the hyperbaric oxygen valve and start gas cutting.

If the preheating place cannot be cut off, it means that the preheating temperature is too low, and the hyperbaric oxygen should be turned off to continue preheating. The front end of the flame center of the preheating flame should be 2 ~ 4 mm away from the surface of the workpiece, and a certain angle should be paid attention to between the cutting torch and the workpiece. When cutting a workpiece with a thickness of 5 ~ 30 mm, the cutting torch should be perpendicular to the workpiece; When the thickness is less than 5mm, the cutting torch can be tilted back by 5 ~ 10.

If the thickness exceeds 30mm, the cutting torch can be tilted forward by 5 ~ 10 at the beginning of gas cutting, and can be perpendicular to the workpiece until the gas cutting is completed. If the preheating area is cut off, continue to increase the amount of hyperbaric oxygen to increase the depth of the incision until it is completely cut through.

During gas welding operation, hold the welding torch with your right hand, put your thumb on the acetylene switch and your forefinger on the oxygen switch, so as to adjust the gas flow at any time. The basic operations of gas welding are: ignition, flame adjustment, welding and flameout.

Extended data

When cutting steel with different thickness, the selection of cutting nozzle and the adjustment of oxygen working pressure are closely related to the quality and efficiency of gas cutting. For example, if the nozzle is too small to cut thick steel, the cutting work cannot be carried out smoothly because of insufficient oxygen combustion and injection capacity. Even if it is cut again and again, the quality is poor and the work efficiency is low.

On the other hand, if an oversized nozzle is used to cut thin steel, it will not only waste a lot of oxygen and acetylene, but also the quality of gas cutting is not good. Therefore, it is necessary to select the size of the cutting opening.

The relationship between the pressure of cutting oxygen and the thickness of metal: insufficient pressure not only slows down the cutting speed, but also makes the slag difficult to blow off, and the incision is uneven and sometimes even impenetrable; When the pressure is too high, in addition to the increase of oxygen consumption, the metal is also easy to cool, thus reducing the cutting speed, widening the incision and making the surface rough.

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