The key technology of metal cutting machine

Several key technologies of metal cutting machines are integrated technologies of optical, mechanical and electrical integration. The parameters of the laser beam, the performance of the machine and the numerical control system, and the accuracy directly affect the efficiency and quality of the Laser Cutting. Especially for parts with high cutting precision or large thickness, the following key technologies must be mastered and solved: 
Focus position control technology: 
One of the advantages of laser cutting is that the energy density of the beam is high, 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 focal depth of the focusing lens, the smaller the focal spot diameter. However, there is splashing and the lens is damaged when the lens is too close to the workpiece. Therefore, the focal length of 5 to 7.5 inches (127 to 190 mm) is widely used in high-power CO2 laser cutting industrial applications. The actual spot diameter is between 0.1 and 0.4mm. For high quality cuts, the effective depth of focus is also related to the lens diameter and the material being cut. For example, the carbon steel is cut with a 5 inch lens, and the depth of focus is within +2% of the focal length, ie about 5 mm. Therefore, it is important to control the position of the focal point relative to the surface of the material being cut. Concerned with the cutting quality, cutting speed and other factors, in principle <6mm metal material, the focus on the surface;> 6mm carbon steel, the focus on the surface;> 6mm stainless steel, the focus is below the surface. The specific size is determined by experiment. 
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 board, print the smallest diameter as the focus. 
2. Inclined plate method: Use a plastic plate tilted at an angle with the vertical axis to pull it horizontally to find the focal point of the laser beam. 
3, blue spark method: remove the nozzle, blowing air, the pulsed laser hit the stainless steel plate, so that the cutting head moves from the top down, until the blue spark is the focus of the largest. 
For the cutting machine of the flying light path, due to the divergence angle of the light beam, the length of the light path is different when cutting the near end and the far end, and the beam size before the 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 focal spot size brought about by the change of the beam size before focusing, manufacturers of laser cutting systems at home and abroad provide some special devices for users to choose: 
1. Parallel light tube, which is a common method, that is, adding a collimator at the output end of a CO2 laser to perform beam expansion processing. After the expanded beam, the diameter of the beam becomes larger and the divergence angle becomes smaller, so that the working range of the cutting can be achieved. The near-end and far-end focus beams are nearly uniform in size. 
2. Add a separate lower axis of the moving lens to the cutting head, and the Z axis which controls the standoff of the nozzle to the material surface are two independent parts. When the machine table moves or the optical axis moves, the beam also moves from the near end to the far end F axis, so that the spot diameter of the Metal Cutting Machine beam is uniform throughout the entire processing area.