Laser cutting is mainly conducted in the form of heat conduction. It can also cut through thick plates in the actual cutting process. However, the greater the thickness, the greater the heat loss, which leads to the reduction of cutting speed and affects the processing efficiency.
1： There are many slags at the bottom of the cutting section. The formation of slags is due to the low average cutting temperature at the bottom of the cutting section and the large energy loss. In this case, the cutting quality is usually not high.
2： The fiber laser spot diameter is small and the focal depth is limited. Although the optical fiber laser cutting machine can maintain a high laser power density in the cutting depth, it is not conducive to cutting and slag discharge because of the small beam diameter and small kerf. This puts forward higher requirements for the collimation mode and range of fiber laser speckle beam scattering, and also brings difficulties to the processing quality of cutting medium thick metal plates.
3： The influence and influence of the quality and pressure of the auxiliary gas. Oxygen plays an important role in fiber laser cutting carbon steel plate. Laser irradiation forms holes on the surface of the workpiece. When the laser beam moves along the cutting direction, there is oxidized melt around the hole and the slit. The purity and pressure of oxygen have great influence on laser cutting. Oxygen with many impurities and inappropriate pressure cannot provide enough energy to the cutting bottom, forming a melt with high fluidity, reducing the cutting quality and cutting speed.
By measuring the quality and pressure of the auxiliary gas at different slit positions, it is found that the narrower the slit is, the worse the effect of the auxiliary gas is, and the more difficult it is to maintain the cutting quality. Therefore, it is very important to ensure the proper slit width, the quality of auxiliary gas and the pressure control of cutting quality. The difference of geometric shape reduces the cutting quality of inflection point. When laser cutting thick plates, the melting rake angle will become prominent, which will lead to the reduction of the laser absorption coefficient of the material, thus ensuring the cutting quality by increasing the cutting power and reducing the cutting speed.
Laser cutting machine will be widely used in the cutting field because of its high point conversion, high cutting accuracy, flexible processing ability, good cutting quality and adaptive performance.
