Several key technologies of laser cutting machine are integrated technologies of light, machine and electricity. In the laser cutting machine, the parameters of the laser beam, the performance and accuracy of the machine and the numerical control system directly affect the efficiency and quality of laser cutting. Especially for the parts with high cutting accuracy or large thickness, the focus position control technology must be mastered and solved.
There are several methods to solve the focus position in the production of laser cutting machine:
(1) Blue spark method: remove the nozzle, blow air, hit the pulse laser on the stainless steel plate, and move the cutting head from top to bottom until the maximum blue spark is the focus. In this way, the focus can be calculated, and the corresponding focus adjustment can be taken according to different plate thicknesses in the subsequent cutting process.
(2) Inclined plate method: use the plastic plate inclined at an angle with the vertical axis to pull it horizontally, and find the minimum position of the laser beam as the focus.
(3) Printing method: move the cutting head from top to bottom, and perform laser beam printing on the plastic plate, with the smallest printing diameter as the focus.
(4) Collimator. This is a common method, that is, a collimator is added to the output end of the CO2 laser to expand the beam. After the beam expansion, the beam diameter becomes larger and the divergence angle becomes smaller, so that the beam size before focusing at the near end and the far end is nearly the same within the cutting working range.
(5) The lower axis of an independent moving lens is added to the cutting head, which is two independent parts from the Z axis that controls the distance between the nozzle and the material surface. When the workbench of the machine tool moves or the optical axis moves, the F-axis of the beam moves from the near end to the far end at the same time, so that the spot diameter after the beam is focused remains the same in the whole processing area