Views: 1 Author: MC Laser Publish Time: 2021-07-08 Origin: MC
The laser cutting machine is to focus the laser light emitted from the laser into a high-power density laser beam through the optical path system. The laser beam irradiates the surface of the workpiece to make the workpiece reach the melting point or boiling point, and the high-pressure gas coaxial with the beam blows away the molten or vaporized metal.
The laser cutting machine processing method has the characteristics of high precision and low processing cost.
Compared with traditional oxyacetylene, plasma and other cutting processes, laser cutting speed is fast, the slit is narrow, the heat-affected zone is small, the edge of the slit is perpendicular, and the cutting edge is smooth. At the same time, there are many types of materials that can be laser cut, including carbon steel. , Stainless steel, alloy steel, wood, plastic, rubber, cloth, quartz, ceramics, glass, composite materials, etc. With the rapid development of the market economy and the rapid development of science and technology, laser cutting technology has been widely used in automobiles, machinery, electricity, hardware, and electrical appliances. In recent years, laser cutting technology is developing at an unprecedented speed, with an annual growth rate of 15% to 20%. Since 1985, my country has grown at a rate of nearly 25% per year. At present, the overall level of my country's laser cutting technology still has a big gap compared with advanced countries. Therefore, laser cutting technology in the domestic market has broad development prospects and huge application space.
During the cutting process of the laser cutting machine, the beam is focused by the lens of the cutting head into a small focal point, so that the focal point can reach a high power density, and the cutting head is fixed on the z-axis. At this time, the heat input by the beam far exceeds the part of the heat reflected, conducted or diffused by the material, and the material is quickly heated to the melting and vaporization temperature. At the same time, a high-speed airflow will melt from the coaxial or non-coaxial side. And the vaporized material is blown out to form holes for cutting the material. With the relative movement of the focus and the material, the hole forms a continuous slit with a very narrow width to complete the cutting of the material.
At present, the outer optical path part of the laser cutting machine mainly adopts the flying optical path system. The light beam emitted from the laser generator reaches the focusing lens on the cutting head through the reflecting mirrors 1, 2, and 3, and forms a light spot on the surface of the material to be processed after focusing. The reflecting lens 1 is fixed on the fuselage without moving; the reflecting mirror 2 on the beam moves in the x direction with the movement of the beam; the reflecting lens 3 on the z axis moves in the y direction with the movement of the z axis. It is not difficult to see from the figure that during the cutting process, as the beam moves in the x direction and the z-axis part moves in the y direction, the length of the light path changes all the time.
Due to the manufacturing cost and other reasons, the laser beam emitted by the civilian laser generator has a certain divergence angle and is "conical". When the height of the "cone" changes (equivalent to a change in the optical path length of the laser cutting machine), the cross-sectional area of the beam on the surface of the focusing lens also changes. In addition, light also has the nature of waves. Therefore, diffraction phenomenon will inevitably occur. Diffraction will cause the beam to expand laterally during propagation. This phenomenon exists in all optical systems and can determine the performance of these systems. Limit value. Due to the "cone" of the Gaussian beam and the diffraction effect of light waves, when the length of the optical path changes, the diameter of the beam acting on the lens surface changes momentarily, which will cause changes in the focus size and depth, but affect the focus position Very small. If the focus size and focus depth change during continuous processing, it will inevitably have a great impact on the processing. For example, it will cause inconsistent cutting slit widths, incomplete cutting or ablation of the plate under the same cutting power.