(1) Printing method: the cutting head is moved from top to bottom, and laser beam printing is performed on the plastic plate, and the smallest diameter is the focus.
(2) Inclined plate method: The plastic plate obliquely placed at an angle to the vertical axis is horizontally pulled, and the minimum point of the laser beam is focused.
(3) Blue spark method: remove the nozzle, blow the air, and pulse the laser on the stainless steel plate to move the cutting head from top to bottom until the blue spark is at the maximum focus.
For the cutting machine of the flying light path, due to the divergence angle of the beam, the length of the optical path is different when the proximal end and the distal end are cut, and the beam size before focusing has a certain difference. The larger the diameter of the incident beam, the smaller the diameter of the focal spot. In order to reduce the change of the spot size caused by the change of the beam size before focusing, the manufacturers of laser cutting systems at home and abroad provide some special devices for users to choose:
(1) Parallel light pipe. This is a commonly used method, in which a parallel light tube is added to the output end of the CO2 laser for beam expansion processing, the beam diameter after beam expansion becomes larger, and the divergence angle becomes smaller, so that the proximal end and the distal end are within the cutting working range. The beam size is close to the same before focusing.
(2) Adding a separate moving lens lower shaft to the cutting head, which is two independent parts from the Z axis that controls the nozzle to stand off from the material surface. When the machine table moves or the optical axis moves, the beam also moves from the proximal end to the distal F axis, so that the spot diameter remains the same throughout the processing area after the beam is focused. As shown in Figure 2.
(3) Control the water pressure of the focusing mirror (generally the metal reflection focusing system). If the beam size becomes smaller before focusing and the focal spot diameter becomes larger, the water pressure is automatically controlled to change the focus curvature to make the focal spot diameter smaller.
(4) The compensation optical path system in the x and y directions is added to the flying optical path cutting machine. That is, when the optical path of the cutting distal end is increased, the compensation optical path is shortened; when the optical path of the cutting proximal end is decreased, the compensation optical path is increased to keep the optical path length consistent.