In the actual cutting process of a metal laser cutting machine, the relative power to cut through the thickness of the sheet is limited, which is related to the principle of laser cutting. Laser cutting is the process of focusing high-power laser onto the surface of the workpiece being cut, melting or burning it, and then using cutting gas to blow away the slag. The cutting head moves on the surface of the workpiece to form a cutting seam and separate the workpiece.
Whether the melting or burning of metal materials can be sustained and stable during the cutting process is the key to ensuring cutting ability and quality. The temperature at the top of the cutting seam must reach the ignition point, and relying solely on the energy released by the combustion reaction between metal and air cannot guarantee the continuous combustion process.
One reason is that the cutting seam is continuously cooled by the oxygen flow sprayed from the nozzle, which reduces the temperature of the cutting surface; The second is that the ferrous oxide layer formed by combustion covers the surface of the workpiece, hindering the diffusion of oxygen. When the concentration of oxygen decreases to a certain extent, the combustion process will be extinguished.
When cutting thick plates, the cutting speed is relatively slow, and the speed of burning on the surface of the workpiece is faster than the speed of the cutting head. After a period of combustion, the combustion process is extinguished due to a decrease in the concentration of oxygen in the air. During the movement of the cutting head, the combustion process of the cutting surface occurs periodically, which can lead to temperature fluctuations at the cutting edge and a decrease in the quality of the cut.
The following technical difficulties exist in metal cutting thick plates:
Maintaining quasi steady state combustion process is relatively difficult
The oxygen purity and pressure in the thickness direction of the 02 plate are difficult to maintain constant
In order to maintain stable cutting, it is required that the purity and pressure of the oxygen flow in the thickness direction of the plate be kept basically constant.
There are generally three ways to solve this problem:
(1) Increase the size of auxiliary airflow;
(2) Match the power level corresponding to the cutting capability;
(3) Adjust the matching cutting rate.
