One of the advantages of the metal laser cutting machine is that the energy density of the beam is high, so the focal spot diameter will be as small as possible in order to produce extremely tiny slits.
In the past, the focus of metal laser cutting machines was manual, so it was troublesome to operate. With the continuous advancement of science and technology, high-performance high-speed laser cutting machine tools have a fully automatic focusing function. Then, some people will say that the optical path is integrated into the cutting head, can’t simply change the laser height? The cutting head is raised, the focus position is higher, and the cutting head is lowered, the focus position is lower. However, it turns out that it is not as simple as everyone thought.
The bottom of the cutting head is a nozzle. During the cutting process, the distance between the nozzle and the workpiece (nozzle height) is about 0.5 to 1.5 mm. It may be regarded as a fixed value, that is, the nozzle height is unchanged, so it cannot be adjusted by lifting the laser head. Coke.
The focal length of the focusing lens cannot be changed, so it is not practical to adjust the focus by changing the focal length. If you change the position of the focus lens, the corresponding is to change the focus position: the focus lens goes down, the focus goes down, and the focus lens goes up, the focus goes up. –This is indeed a way of focusing. A motor is used to drive the focusing lens to move up and down to achieve automatic focusing.
Another automatic focusing method is: before the beam enters the focusing mirror, a variable curvature mirror (or adjustable mirror) is set, and the divergence angle of the reflected beam is changed by changing the curvature of the mirror, and the focus position is changed.
With the automatic focusing function, when processing workpieces of different materials and different thicknesses, the machine can automatically adjust the focus to a suitable position automatically by means of numerical control. This can significantly improve the processing efficiency of high-speed laser cutting machine tools, and the perforation time of thick plates will also be greatly reduced.
Therefore, for high-speed laser cutting machine tools, the automatic focusing function is an important and indispensable function.