The laser cutting machine needs to be equipped with auxiliary gases, mainly oxygen, nitrogen and air. When processing the workpiece, the optical fiber laser cutter is irradiated by the laser focus, the irradiated area will melt and vaporize instantly, and then move the irradiation position of the point through the CNC equipment system to achieve automatic cutting.
1. Compressed air.
Air is suitable for cutting aluminum sheet and galvanized steel sheet. To some extent, it can reduce the oxide film and save the cost. Generally, it is used when the cutting plate is relatively thick and the requirements on the cutting end face are not too high.
2. Nitrogen.
Nitrogen is an inert gas, which can prevent oxidation and combustion of the cutting end of the product during cutting (it is easy to happen when the plate is thick. Nitrogen can be selected for products that need high cutting end and are not exposed to high temperature).
3. Breathe oxygen.
It acts as a combustion promoter and can increase the cutting speed and thickness. Oxygen is suitable for thick plate cutting, high-speed cutting and thin plate cutting, such as some large carbon steel plates and some thick carbon steel plate structural components. Oxygen can be used. Increasing the air pressure can increase the cutting speed, but after reaching the set value, continuing to increase the air pressure will reduce the cutting speed.
When the auxiliary gas pressure is high, the reason for the reduction of cutting speed can be attributed to the higher pressure. In addition to enhancing the cooling effect and action area of the air flow, the intermittent shock wave in the air flow may interfere with the cooling of the air flow. Laser area. The non-uniformity of pressure and temperature in air flow will cause the change of air flow field density.
Such a density gradient will cause the refractive index in the field to change, which will lead to focusing, thus causing refocusing or beam divergence. This interference will affect the melting efficiency, and may sometimes change the mode structure, resulting in a decline in cutting quality. If the beam divergence is too large, making the spot too large may lead to serious consequences, resulting in the inability to effectively perform cutting.
Application of auxiliary gas:
1. Compressed air: It is widely used in the processing of some sheet metal cabinets and other products.
2. Nitrogen: processing of some decoration industries, aerospace and other parts;
The laser cutting machine uses different auxiliary gases to cut different materials. The pressure and required flow rate of auxiliary gas vary with the thickness of the cutting material.