In the actual cutting process of the metal laser cutting machine, the thickness of the plate that the power can cut through is limited, which is related to the principle of laser cutting. Laser cutting is the process of focusing a high-power laser on the surface of the workpiece to be cut, melting or burning it, supplemented by cutting gas, chasing away the slag, and moving the cutting head on the surface of the workpiece to form a slit, so that the workpiece is separated.

In the cutting process, whether the melting or burning of the metal material can be sustained and stable is the key to ensure the cutting ability and quality. The temperature at the top of the slit must reach the ignition point, and the energy released by the metal and air combustion reaction alone does not actually ensure that the combustion process continues.

First, because the slit is continuously cooled by the oxygen flow from the nozzle, the temperature of the cutting surface is reduced; Second, the layer of ferrous oxide formed by combustion covers the surface of the workpiece, hindering the diffusion of oxygen, and when the concentration of oxygen is reduced to a certain extent, the combustion process will be extinguished.

When cutting thick plates, the cutting speed is relatively slow, and the burning speed of the workpiece surface is faster than the speed of the cutting head. After the combustion continues for a period of time, the concentration of oxygen in the air decreases, resulting in the combustion process being extinguished. When the cutting head is moving, the burning process of the cutting surface is carried out periodically, which will lead to the temperature fluctuation of the cutting front, and the quality of the incision becomes worse.

There are the following technical difficulties in metal cutting thick plates:

1. Quasi-steady combustion process is difficult to maintain

2. The oxygen purity and pressure of plate thickness direction are difficult to maintain constant

In order to maintain the stability of cutting, the purity and pressure of cutting oxygen flow in the direction of plate thickness are required to remain basically constant. There are generally three ways to solve this problem:

(1) Increase the size of the auxiliary air flow;

(2) Match the power of the corresponding cutting capacity

(3) Adjust the matching cutting speed.