The cutting quality of a flat bevel fiber laser cutting machine largely depends on the relative positional accuracy between the laser focus and the workpiece surface. Especially in bevel cutting scenarios, the sloping features on the surface of the workpiece double the difficulty of controlling the focal position, making the automatic focusing system the core component of the equipment to ensure machining stability. Its core function is to real-time correct the position deviation between the focus and the workpiece surface, always maintain the optimal cutting energy state, and avoid the efficiency loss and accuracy fluctuation caused by manual focusing.

The core principle of autofocus is based on closed-loop control logic, with "energy matching" as the core objective. The best effect of laser cutting corresponds to a specific focal position, where the laser energy density is concentrated, the material melting and vaporization efficiency is high, and a smooth cutting seam and precise groove angle can be formed. The system collects real-time deviation signals between the focal position and the workpiece surface through sensing units. After filtering and computing the signals by the controller, adjustment instructions are generated to drive the actuator to correct the focal position deviation, forming a closed-loop loop of "detection operation adjustment" to dynamically maintain focal accuracy.

Sensing detection is a prerequisite for achieving automatic focusing, and mainstream technology paths have their own adaptation scenarios. Capacitive sensing technology senses distance deviation by detecting changes in capacitance between the laser head and the workpiece, and has strong resistance to cutting dust and splash interference. It is suitable for groove cutting of common metals such as carbon steel and stainless steel; Laser triangulation technology calculates distance by emitting an auxiliary laser beam and using the position offset of the reflected beam. It has better adaptability to materials with higher surface smoothness and can accurately capture the position changes of bevel slopes. Both technologies can meet the detection needs of groove cutting and can be adapted according to the characteristics of the processing material.

The precise response of the execution adjustment module is the key to the implementation of the principle. This module usually consists of a drive unit and a transmission mechanism. The mainstream configuration is to use a servo motor with a ball screw - the servo motor receives precise speed control commands from the controller, and the ball screw converts rotational motion into linear motion, driving the laser head to smoothly lift and lower to adjust the focal position. For high-speed bevel cutting scenarios, some equipment is driven by linear motors, which improve response speed and reduce adjustment lag with the advantage of non-contact transmission. Some systems also integrate optical focusing components, which change the focal length of the optical path by driving the lens group with a motor, achieving faster focus switching.

Software algorithms provide intelligent decision support for the system. The algorithm establishes a parameter library by presetting the optimal focus parameters corresponding to different materials, thicknesses, and groove angles. During processing, combine the groove path information in the CNC program to predict the trend of changes in the focus position and issue adjustment instructions in advance; Simultaneously possessing adaptive learning ability, optimizing parameters based on feedback signals during the cutting process to ensure sustained stability in complex bevel cutting scenarios.