Views: 7 Author: Site Editor Publish Time: 2019-11-29 Origin: Site
When laser cutting machine cuts parts with high precision or thickness,
Focus position control is one of them. One of the advantages of laser cutting is the high energy density of the beam, so the diameter of the focal spot is as small as possible in order to create a narrow slit. Because the smaller the focal depth of the focusing lens, the smaller the focal spot diameter. For high-quality cutting, the effective focal depth is also related to the lens diameter and the material being cut. It is therefore important to control the position of the focal point relative to the surface of the material being cut.
Since the laser power density has a great influence on the cutting speed, the choice of lens focal length is an important issue. After focusing, the spot size of the laser beam is proportional to the focal length of the lens. The spot size of the beam after focusing by the short focal length lens is small, and the power density at the focal point is very high, which is very beneficial for material cutting. However, it has the short focal depth and the adjustment margin. Small, generally suitable for high-speed cutting of thin materials. Because the telephoto lens has a wide focal depth, as long as it has sufficient power density, it is more suitable for cutting thick workpieces.
After determining which focal length lens is used, the relative position of the focal point and the surface of the workpiece is particularly important to ensure the quality of the cut. Due to the high power density at the focal point, in most cases the focal position is just at the surface of the workpiece or slightly below the surface during cutting. During the entire cutting process, ensuring that the relative position of the focal point and the workpiece is constant is an important condition for obtaining stable cutting quality. Sometimes, the focal length changes due to the heat of the lens due to poor cooling, which requires timely adjustment of the focal position.
When the focus is in the proper position, the slit is small, the efficiency is high, and the cutting speed can obtain good cutting results. In most applications, the beam focus is adjusted just below the nozzle. The distance between the nozzle and the surface of the workpiece is generally about 1.5mm.