What Is Oxygen Cutting?

Oxygen cutting is a method that uses the thermal energy of a gas flame to preheat the cutting part of the workpiece to the ignition point, and then sprays a high-speed cutting oxygen stream to burn the metal and release heat to achieve the cutting. There are three types of manual, semi-automatic and automatic gas cutting according to the torch moving mode.

Oxygen cutting is referred to as gas cutting. It has the advantages of simple equipment, flexibility, convenience, and good quality. It is suitable for cutting thick and long-sized scrap steel, such as large scrap steel plates, steel castings, waste boilers, and waste steel structural frames. It is more flexible and convenient for the disintegration of waste cars and the disintegration of old ships. It is not restricted by the narrow space of the site or the size of objects, and can be operated in any occasion. In addition to using gas cutting to process steelmaking furnace materials, you can also cut valuable materials such as plates, shapes, and pipes from scrap steel for production use. Therefore, oxygen cutting is one of the main methods of scrap steel processing, and it is currently widely used in metal recycling departments.

Oxygen cutting of steel uses a gas flame (called a preheating flame) to heat the surface of the steel to the ignition point and form an activated state, and then sends high-purity, high-flow cutting oxygen to burn iron in the steel to generate oxidation in an oxygen atmosphere. Iron slag emits a lot of heat at the same time. With the heat of combustion and slag, the lower layer of steel and the leading edge of the cut are continuously heated to reach the ignition point to the bottom of the workpiece. At the same time, the momentum of the cutting oxygen stream blows away the slag, forming a cut to cut the steel. Therefore, from a macro perspective, oxygen cutting is a processing method that combines the chemical process of burning iron in steel (broadly speaking, metal) in high-purity oxygen and the physical process of removing slag by the flow of cutting oxygen. .

First open the preheated oxygen and acetylene valves, ignite the preheated flame, adjust the flame to a neutral flame, heat the starting point of the T-piece cut to above the ignition point, and then open the cutting oxygen valve. High-temperature T-pieces immediately produce a violent oxidation reaction, and the liquid oxide is quickly blown away by the oxygen flow; the next layer contacts the oxygen and continues to burn, so the oxygen can burn the cut metal from the surface to the deep layer and even penetrate As the torch moves forward, the T piece forms a cut. ^[1]

(1) The ignition point of the material to be cut should be lower than the melting point to ensure that the combustion is performed in a solid state, otherwise a neat cut cannot be formed.

(2) The melting point of the metal oxide formed by combustion should be lower than the melting point of the metal itself. When the oxide formed by combustion is blown away in a liquid state, the metal at the notch has not yet melted.

(3) The heat emitted during metal burning should be sufficient to preheat the surrounding metal, so that the temperature of the metal at the cutting point 1: I can be maintained above the ignition point, so that the cutting process can be continued.

Of the common metals, only steel is easy to gas cut, and the most commonly used is gas cutting of low carbon steel and low alloy steel. Cast iron, non-ferrous metals, and stainless steel cannot be gas-cut.

(1) First select the appropriate oxygen pressure and cutting nozzle according to the thickness of the workpiece, use a neutral flame as a preheating flame, and check whether the pure oxygen jet is thin and straight.

(2) At the beginning of gas cutting, first heat the edge of the cutting piece to the metal ignition temperature, and slowly open the oxygen valve at the same time, the workpiece is cut through to form a cutting seam.

(3) Keep the distance between the cutting nozzle and the workpiece during the cutting process. The distance is generally 3 ~ 5mm. It should be uniform throughout the gas cutting process, not too fast, so as to prevent the metal plate from cutting through and the oxide metal splashing, resulting in Fire occurs (if the same fire occurs, the acetylene valve should be closed immediately).

(4) When the gas cutting is nearing the end point, the cutting nozzle should be tilted back slightly along the cutting direction, so that the lower part of the T piece is cut through in advance to ensure the quality of the slit at the end.

(5) At the end of gas cutting, the cutting oxygen valve should be closed first, and then the acetylene and preheating oxygen valves should be closed. ^[2]