Laser cutting machine cutting several key technologies is light, mechanical and electrical integration of integrated technology. Laser beam parameters, machine and numerical control system performance and accuracy have a direct impact on the efficiency and quality of laser cutting. Especially for the cutting accuracy or thickness of the larger parts, we must master and solve the following key technologies:
1, the focus position control technology:
One of the advantages of laser cutting is the high energy density of the beam, typically> 10 W / cm2. Since the energy density is proportional to 4 / πd2, the focal spot diameter is as small as possible to produce a narrow slit; the focal spot diameter is also proportional to the focal depth of the lens. The smaller the focusing lens focal depth, the smaller the focal spot diameter. But the cutting is spattered, the lens is too close to the workpiece is easy to damage the lens, so the general high power laser cutting industry widely used 5〃 ~ 7.5〃 "(127 ~ 190mm) focal length. The actual focal spot diameter of 0.1 ~ 0.4mm For high-quality cutting, the effective depth of focus is also related to the diameter of the lens and the material to be cut, for example, with a 5-inch lens cut carbon steel, the depth of focus is within +2% of the focal length, In the cut material surface is very important.Consider the cutting quality, cutting speed and other factors, in principle <6mm of metal material, the focus on the surface;> 6mm carbon steel, the focus on the surface;> 6mm stainless steel, The focus is under the surface. The exact size is determined experimentally.
2, there are three easy ways to determine the focus position in industrial production:
(1) printing method: the cutting head from top to bottom movement, laser beam printing on the plastic plate, print the smallest diameter at the focus. (2) Ramp method: Use a plastic plate diagonal to the vertical axis to pull it horizontally to find the smallest point of the laser beam. (3) blue spark method: Remove the nozzle, blowing air, the pulse laser hit the stainless steel plate, the cutting head from top to bottom movement, until the maximum blue laser focus.
For the flying light path of the cutting machine, due to the beam divergence angle, cutting the proximal end and distal end of the optical path length is different, there is a certain difference between the beam size before focusing. The larger the diameter of the incident beam, the smaller the diameter of the focal spot. In order to reduce the change of focal spot size caused by the change of beam size before focusing, domestic and foreign laser cutting system manufacturers provide some special devices for users to choose:
(1) collimator. This is a commonly used method, that is, a parallel light pipe is added at the output end of the CO2 laser to expand the beam, the expanded beam diameter becomes larger and the divergence angle becomes smaller, so that the proximal end and the distal end within the cutting working range The beam size before focusing is nearly the same. (2) Add a separate movable lens lower shaft to the cutting head, which is independent of the Z axis that controls the nozzle stand off from the material surface. When the machine table is moved or the optical axis is moved, the beam moves from the near end to the far end F-axis at the same time. After the beam is focused, the spot diameter is consistent throughout the machining area.
Article Source: Fuyang rules plastic machinery
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