The main components of the cutting head are laser cutting technology, which is a non-contact processing technology using laser as energy. It is widely used in metal cutting, automobile manufacturing, aerospace and other fields with its own advantages. The laser cutting head is a key component of the laser cutting machine. Taking the fiber cutting head as an example, its main components include fiber connection module, collimation module, focusing module, protective window module, non-contact sensor, cutting nozzle, etc.
The optical fiber is connected to the cutting head from the connection module interface. The collimation module converges the divergent laser into a parallel beam, and finally focuses it into a light spot through the focusing module for cutting. The protective mirror can isolate the outside world from the internal optical path of the cutting head to ensure The sealing of the optical path extends the service life of the fiber cutting head. During cutting, the cutting auxiliary gas forms a high-speed airflow in the inner cavity of the cutting nozzle, which can blow away the molten material. During the cutting process, the sensor and the Z-axis servo motor form a closed-loop control system to automatically sense the distance between the cutting nozzle and the sheet surface. When the flatness of the cut sheet changes, the Z-axis servo motor automatically compensates to make it The distance remains constant, thus ensuring optimal cut quality.
Focus control technology
Focus diameter
The laser beam focused by the cutting head is a Gaussian beam, and the power density is greatly improved after focusing, making it easier to cut the workpiece. The so-called focus is the beam waist of the Gaussian beam. The beam waist diameter is generally used to characterize the size of the focus, and the spot diameter is closely related to the cutting quality. The optical path principle of the fiber cutting head is to reduce the divergence angle of the light beam, and the laser beam needs to be collimated before the laser enters the focusing module of the cutting head.
Focus position control
When a laser cutting machine cuts a workpiece, it not only requires high precision, but also ensures cutting quality, which requires precise control of the focus of the cutting head. Different cutting materials have different focus positions. Generally, when cutting thin mild steel plates, the focus is on the surface of the workpiece; when cutting thick mild steel plates, the focus is on the upper part of the workpiece surface; when cutting stainless steel and aluminum plates, the focus is on the surface of the workpiece. Down. There are three main methods for controlling the focus position of the cutting head: F-axis focusing, variable curvature mirror focusing and collimation module focusing. F-axis focusing controls the focus position by changing the position of the focusing mirror. The movement amount of the focus position is the movement amount of the focusing mirror position.
Focus diameter control
Focus diameter control is also called zoom, which changes the spot diameter at the focus. Zoom technology is mainly used in thick plate cutting and improving thick plate perforation efficiency. When cutting thin plates at high speed, a small spot diameter is conducive to increasing energy density and small slits, which facilitates high-speed cutting; when cutting thick plates, a large spot diameter increases the width of the slits, which is beneficial to slag discharge, and can also obtain larger The depth of focus and high cross-section verticality are beneficial to improving cutting quality.
Conclusión
The application of automatic focusing and automatic zoom technology on laser cutting machines is becoming more and more widespread, allowing laser cutting machines to cut plates of different thicknesses and types without manual intervention, greatly improving the degree of automation and productivity, and leading a new market trend. Reasonable cutting head focus control plays a key role in the quality and cutting speed of laser cutting. (1) Focus position control technology mainly includes F-axis focusing, variable curvature mirror focusing and collimation module focusing. The focus position change amount of F-axis focusing is the movement amount of the focusing mirror position; the focus position change amount of variable curvature mirror focusing is linearly related to the pressure change value, and the focusing speed is faster; during the collimation module focusing, the focus position The ratio of the movement amount to the alignment module movement amount is approximately f 2 F /f 2 C. (2) In addition to achieving zooming by replacing the focusing lens or collimating lens or the beam diameter φ, focus diameter control can also be used to continuously and quickly change the spot diameter by moving the position of the adjustment mirror in the collimation module according to the principle of continuous zooming.
