1、 Relationship between nozzle and cutting quality:
When the center of the nozzle is different from the center of the laser, the influence on the cutting quality:
1) It affects the cutting section. When the cutting gas is ejected, it causes uneven air volume, which makes the cutting section more prone to the phenomenon of melting stains on one side and no melting stains on the other side. It has little impact on the cutting of thin plates less than 3mm. When cutting plates more than 3mm, its impact is more serious, and sometimes it will cause failure to cut.
2) It affects the quality of sharp corners. When cutting workpieces with sharp corners or small angles, it is easy to produce local over melting. When cutting thick plates, it may not be able to cut.
3) It affects the perforation. It is unstable during the perforation, and the time is not easy to control. The penetration of thick plates will cause over melting, and the penetration conditions are not easy to grasp, which has little impact on the perforation of thin plates.
2、 Selection of nozzle aperture:
The hole diameter of the nozzle is φ 1.0mm、 φ 1.5mm、 φ 2.0mm、 φ 2.5mm、 φ 3.0mm, etc. At present, nozzle aperture is often used φ 1.5mm、 φ 2mm. The difference between the two is:
1) Sheet less than 3mm: use φ 1.5mm, the cutting surface will be fine; use φ 2mm, the cutting surface will be thick, and the corner is easy to have melting stains.
2) Thick plates above 3mm: due to high cutting power, the relative heat dissipation time is longer, and the relative cutting time also increases. use φ 1.5mm, the gas diffusion area is small, so it is not stable when used, but it is basically available. use φ 2mm, the gas diffusion area is large, and the gas flow rate is slow, so it is relatively stable during cutting.
3) Diameter φ The hole diameter of 2.5mm can only be used for cutting thick plates above 10mm. To sum up, the size of nozzle aperture has a serious impact on the cutting quality and perforation quality. At present, laser cutting is mostly used φ 1.5mm、 φ 2mm diameter nozzle.
Therefore, the larger the nozzle aperture is, the worse the protection of the focusing lens is. Because the sparks of molten materials splash during cutting, there is a great chance of bouncing upward, which makes the life of the lens shorter.
The concentricity between the center of the nozzle and the laser is one of the important factors causing the cutting quality, especially when the thicker the workpiece is cut, its influence is greater. Therefore, the concentricity between the nozzle center and the laser must be adjusted to obtain a better cutting section.
Note: when the nozzle is deformed or there is molten stain on the nozzle, its impact on the cutting quality is the same as that described above. Therefore, the nozzle should be placed carefully without bumping to avoid deformation; The molten stains on the nozzle should be cleaned in time. The quality of nozzle requires high accuracy in manufacturing and correct method in installation. If various conditions need to be changed during cutting due to the poor quality of the nozzle, the nozzle should be replaced in time.