Method of automatic focusing
1.When cutting different materials, the focus of the laser beam is required to fall on different positions of the cross-section of the work piece, as shown in the figure, so it is necessary to constantly adjust the focus position.
Someone think that as long as the height of the cutting head is changed, the cutting head rises, the focus position rises, and the cutting head lowers, the focus position decreases. In fact, it is not that simple.
As we all know, the bottom of the cutting head is the nozzle. During the cutting process, the distance between the nozzle and the work piece (nozzle height) is about 0.5～1.5 mm, which is a fixed value, that is, the nozzle height does not change, so you cannot adjust the focus by lifting the cutting head. , Otherwise the cutting process cannot be completed.
The focal length of the focusing lens cannot be changed, so the focus cannot be adjusted by changing the focal length. Changing the position of the focusing lens can change the focus position: when the focusing lens drops, the focus drops; when the focusing lens rises, the focus rises. This is also a commonly used automatic focusing method, which drives the focusing lens to move up and down through a motor.
2.Another method of automatic focusing is to configure a variable curvature of reflector before the beam enters the focusing lens, and change the divergence angle of the reflected beam by changing the curvature of the reflector, thereby changing the focus position.