Although the nozzle is an inconspicuous small component, its function is not small. It not only needs to resist the upward rebound of impurities such as molten stains, but also controls the gas diffusion area. Therefore, nozzle’s quality of laser pipe cutting machine is one of the important factors determining the quality of cutting. Today, we will talk about how to choose a nozzle.
1. Single layer laser nozzle
The structure of a single-layer laser nozzle in tube laser cutting system is relatively simple, with only one layer of air ports, fixed jet direction, and a large opening of the nozzle, suitable for cutting medium thickness metal materials. During the cutting process, the airflow velocity of a single-layer nozzle is slower than that of a double-layer nozzle, and the jet range is relatively short.
2. Double layer laser nozzle
The structure of a double-layer laser nozzle is more complex than that of a single-layer nozzle in laser pipe cutter, with two layers of air ports inside. The airflow can be adjusted according to needs, corresponding to different thicknesses of cutting materials. Due to the smaller jet direction and nozzle opening, the jet speed is fast and the jet range is relatively long, which can better adapt to the cutting needs of materials with different thicknesses.
On the surface, there is not much difference between single-layer and double-layer nozzles, but in reality, there are significant differences in jet speed and jet range between the two. The airflow speed of a single-layer nozzle is relatively slow, which is only suitable for cutting medium thickness materials; The double-layer nozzle has a very fast airflow speed and is suitable for cutting metal materials of various thicknesses. In addition, the double-layer nozzle can reduce the oxidation degree of the cutting material surface and improve the cutting quality due to its fast airflow speed and long jet range.
A single-layer laser nozzle is used for melting and cutting, which uses nitrogen as an auxiliary gas to cut stainless steel and aluminum plates, etc., using a single-layer laser nozzle with a specification of 1.4-3.0mm. Double layer laser nozzles are generally used for oxidation cutting, which uses oxygen as an auxiliary gas for cutting carbon steel. Double layer laser nozzles with specifications of 1.5-3.0 are used.
3. How to choose the nozzle of a laser cutting machine?
(1) Size of nozzle. Select the nozzle size based on the thickness of the metal sheet cut by the user. The aperture of the nozzle controls the gas flow rate and the shape of the gas field, which is very important for cutting quality. When using a laser cutting machine to cut thin plates below 3mm, it is recommended to use a nozzle with a diameter of 1mm, while a nozzle with a diameter of 1.5mm is recommended for thicknesses above 3mm. When cutting metal plates with a diameter of 10mm or more, a nozzle with a diameter of 2mm or more is generally chosen.
(2) Material of the nozzle . A good nozzle must be made of a material with high conductivity and good thermal conductivity. Generally, nozzles made of copper material are better than those made of brass material, ensuring a good capacitive signal.
(3) Processing accuracy of nozzles. A good laser head nozzle should have a concentricity of 0.03mm, while nozzles with dimensions below 1.0mm should have a concentricity of 0.02mm. A high-precision concentric nozzle can not only reduce the initial debugging during the processing process, but also effectively prevent high-energy laser from hitting the inner wall of the laser head, thereby avoiding damage to the laser head.
(4) Surface smoothness and anti oxidation treatment of the nozzle. A smooth surface and good anti oxidation treatment can effectively reduce the adhesion of molten substances during the cutting process and extend the service life of the nozzle.