Laser cutting machine double-value constant equal length optical path compensation system

by:Lxshow     2021-05-21

General fiber laser cutting machines have their own optical path according to the laser type. The divergence angle Θ of the fast axial flow CO2 laser is usually 2 mrad (that is, the beam diameter increases by 2 mm for every extension of the laser beam by 1 m).

As the propagation distance of the beam increases, the beam diameter gradually increases, and the change of the beam diameter means the change of the focus position, which has a very large impact on the cutting quality. For thin plates and thick plates, there are different and better cutting optical path lengths. Only the double-value constant length optical path cutting effect is the most ideal. It can not only meet the cutting of thin plates, but also meet the cutting of thick plates, and the total length of the cutting time path remains unchanged. . At present, the optical path length required for thin plate cutting has been successfully applied, but sometimes it is necessary to cut thick plates. Therefore, this article introduces two optical path design ideas for thin plates and thick plates.

Dual-value constant-length optical path compensation system

The dual-value constant-length optical path compensation system of fiber laser cutting machine is an intelligent and fully automatic optical path length restriction mechanism, which effectively controls With the laser cutting machine changing the beam diameter in the entire processing range, it also satisfies the need for better cutting of thin and thick plates. The optical path length is used to control the thickness of the plate to move the laser to the corresponding position according to the X and Y strokes. The different position data of the compensation axis is automatically calculated, and the compensation axis servo motor is controlled by the system to determine the position of the compensation axis. The total length transmitted by the optical path of the cutting head is kept unchanged to ensure that the beam diameter at the cutting head remains unchanged, which indirectly ensures The focus position and focal spot diameter are stable. The propagation principle of the dual-value constant equal-length optical path compensation system: when the cutting head cuts at any position of the workpiece, the total optical path length from the laser light outlet to the cutting head remains unchanged; at the same time, for thin and thick plates, it is better to move the laser to change the optical path length Cut the length of the optical path.

When the cutting head moves to workbench position 1 for processing, the mirrors 1 and 2 move to A1B1 in the constant-length optical path control unit according to the compensation principle. At this time, the total optical path length is L1u003dOA1+ A1B1+B1C+CD1+D1E1; when the cutting head moves to workbench position 2 for processing, the light path path L2u003dOA2+A2B2+B2C+CD2+D2E2; when processing 3 positions the same path L3u003dOA3+A3B3+B3C+ CD1+D1E3; when processing 4 locations, the path L4u003dOA4+A4B4+B4C+CD2+D2E4, as long as the total length of the optical path of processing 1, 2, 3, 4 remains the same, that is, L1u003d L2u003dL3u003dL4, you can The total stroke of the constant-length optical path compensation control unit is calculated as A1A4u003d(D1D2+E1E3)/2, D1D2 is equivalent to the Y-axis stroke of the machine tool, E1E3 is equivalent to the X-axis stroke of the machine tool, and so on, the compensation principle is : The moving distance of the mirror of the constant-length optical path compensation control unit is half (x+y)/2 of the compound moving distance of the X-axis and Y-axis. The above are only processing paths for the 4 extreme positions. Of course, they can be divided in more detail. The division principle is also based on the compensation principle. No matter where the cutting head is processed on the worktable, the total length of the laser light path remains the same, the beam diameter remains the same, and the focus position remains the same, ensuring stable and reliable cutting quality. When cutting thin plates, automatically move the laser to the dotted line to meet a better optical path length and achieve a suitable cutting optical path. The constant-length optical path compensation control unit has the same principle as the thick plate cutting, keeping the total optical path length unchanged during cutting.

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