The laser cutting machine needs to be equipped with auxiliary gases during use, mainly oxygen, nitrogen and air. When the fiber laser cutting machine is processing the workpiece, it will be irradiated by the laser focal spot, and the irradiated area will be instantly melted and vaporized, and then the spot irradiation position is moved through the numerical control equipment system to realize automatic cutting.
1. Compressed air.
Air is suitable for cutting aluminum plates and galvanized steel plates. To a certain extent, it can reduce oxide film and save costs. Generally, it is used when the cutting plate is relatively not thick and the requirements for the cutting end face are not too high.
Nitrogen is an inert gas, which prevents oxidation of the cut end surface of the product during cutting and prevents combustion (it easily occurs when the sheet is thick. Nitrogen can be selected for products that have higher requirements on the cut end surface and are exposed to the outside without processing.
Oxygen mainly plays a role in supporting combustion. It can increase the speed during cutting and increase the thickness of the cutting. Oxygen is suitable for thick plate cutting, high-speed cutting and thin plate cutting. For example, some larger carbon steel plates and some thicker carbon steel structures can use oxygen.
Increasing the gas pressure can increase the cutting speed, but after reaching a set value, continuing to increase the gas pressure will cause the cutting speed to drop. Under high auxiliary gas pressure, the reason for the decrease in cutting speed can be attributed to the high air velocity and the enhancement of the cooling effect of the action area, and it may also be the interference of the intermittent shock wave existing in the airflow on the cooling of the laser action area.
There are uneven pressure and temperature in the airflow, which will cause the change of the airflow field density. Such a density gradient results in a change in the refractive index in the field, thereby constricting the focus of the beam energy, causing refocusing or beam divergence. This interference will affect the melting efficiency, and sometimes may change the mode structure, resulting in a decrease in cutting quality, if the beam diverges too much. If the light spot is too large, it may even cause serious consequences of not being able to cut effectively.
Application of auxiliary gas:
1. Compressed air: It is widely used in the processing of some sheet metal chassis, cabinets, cabinets and other products.
2, Nitrogen: processing some parts of the decoration industry, aerospace and other parts;
Laser cutting machine uses different auxiliary gases to cut different materials. The pressure and required flow rate of the auxiliary gas vary with the thickness of the cutting material.