In general, when using the flame cutting method, three cutting flames can be obtained by adjusting the ratio of oxygen to acetylene: oxidizing flame, reducing flame. Neutral flame (ie normal flame)
The oxidant flame is produced in the case of excess oxygen. The flame core is conical, the length is obviously shortened, the outline is not clear, and the brightness is dim. Similarly, the reduction zone and the outer flame are shortened, and the flame is purple-blue. The sound is accompanied by a sound, and the sound is related to the pressure of oxygen. The temperature of the oxidizing flame is higher than that of the normal flame. If the oxidizing flame is used for cutting, the quality of the cutting will be significantly deteriorated.
The reducing flame is produced in the case of excess acetylene. The flame core has no obvious contour, and the end of the flame core has a green edge. According to the green edge, there is excess acetylene; the reduction zone is abnormally bright, almost The flame core is mixed; the outer flame is yellow. When there is too much acetylene, it starts to smoke, because acetylene combustion in the flame lacks the necessary oxygen.
The normal flame is characterized by no free oxygen and activated carbon in its reduction zone, with three distinct areas, and the flame core has a sharp outline (close to a cylindrical shape). The composition of the flame core is acetylene and oxygen, and its ends are uniformly round and shiny. The outer shell consists of red hot carbon dots. The temperature of the flame core reaches 1000 °C . The reduction zone is outside the flame core and the distinct difference from the flame core is its darkness. Reducing zone from the product of incomplete combustion of acetylene - carbon monoxide and hydrogen, the temperature of the reduction zone up to about 3000 ℃. The outer flame is the complete combustion zone, which is located outside the reduction zone. It consists of carbon dioxide and water vapor, nitrogen, and its temperature varies between 1200 and 2500 °C .
The energy of the preheating flame is closely related to the cutting speed and the quality of the cut. As the thickness of the workpiece to be cut increases and the cutting speed increases, the energy of the flame should also increase, but it should not be too strong, especially when cutting thick plates, the heat of reaction generated by metal burning increases, and the cutting is strengthened. The preheating capacity of the leading edge, at this time, the excessive preheating flame will cause the upper edge of the slit to melt and collapse. A too weak preheating flame will cause the steel plate to not get enough energy, which will reduce the cutting speed and even interrupt the cutting process. Therefore, the relationship between the strength of the preheating flame and the cutting speed is mutually restricted.
When cutting a large-thickness steel plate, the reducing flame should be preheated and cut, because the flame of the reducing flame is relatively long, and the length of the flame should be at least 1.2 times the thickness of the plate . In general, cutting a steel plate of 200 mm or less can achieve better cutting quality by using a neutral flame. Â
Flame adjustment is no longer a problem