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Main process classification and description of laser cutting

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Industry News
Release time:
2018/09/29
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Abstract: Under the heating of high power density laser beam, the surface temperature of the material rises to the boiling point temperature so fast that it avoids the melting caused by heat conduction, so some materials are vaporized into vapor disappearing, and some materials are used as the ejected material from the slit. The bottom is blown away by the auxiliary gas stream. The laser cutting temperature exceeds 11000 ° C, enough to vaporize any material, so when laser cutting. In addition to melting, gasification also plays an important role. The laser cutting process of some materials (such as carbon and some ceramics) is purely a gasification process.
 
Main process classification and description of laser cutting
 
l, gasification laser cutting processing.
Under the heating of the high power density laser beam, the surface temperature of the material rises to the boiling point temperature so fast that it is sufficient to avoid melting caused by heat conduction, so that some of the material vaporizes into vapor and some of the material is ejected from the bottom of the slit. The auxiliary gas stream is blown away. The laser cutting temperature exceeds 11000 ° C, enough to vaporize any material, so when laser cutting. In addition to melting, gasification also plays an important role. The laser cutting process of some materials (such as carbon and some ceramics) is purely a gasification process.
2. Melting laser cutting processing.
When the power density of the incident laser beam exceeds a certain value, the inside of the material at the beam irradiation point evaporates to form a hole. Once such a small hole is formed, it will absorb all of the incident beam energy as a black body. The aperture is surrounded by the molten metal wall and then an auxiliary gas stream coaxial with the beam carries away the molten material around the hole. As the workpiece moves, the small holes are simultaneously traversed in the cutting direction to form a slit. The laser beam continues to illuminate along the leading edge of the slit, and the molten material is blown away from the slit continuously or pulsatingly.
3. Oxidation melting laser cutting processing.
Melting and cutting generally uses an inert gas. If it is replaced by oxygen or other reactive gas, the material is ignited under the irradiation of a laser beam, and a strong chemical reaction with oxygen produces another heat source called oxidative melting cutting.
4, control fracture laser cutting processing
For brittle materials that are easily damaged by heat, high-speed, controlled cutting by laser beam heating is called controlled fracture cutting. The main content of this cutting process is that the laser beam heats the small area of ​​the brittle material, causing a large thermal gradient and severe mechanical deformation in the area, resulting in the formation of cracks in the material. As long as a balanced heating gradient is maintained, the laser beam can direct the crack to occur in any desired direction.
CO2 laser cutting: Laser cutting is mainly CO2 laser cutting. CO2 laser cutting uses a focusing mirror to focus the CO2 laser beam on the surface of the material to melt the material, while blowing the melted material with a compressed gas coaxial with the laser beam. The laser beam and the material are moved relative to each other along a certain trajectory to form a slit of a certain shape. The obvious advantages of CO2 laser cutting technology over other methods are:
(1) Good cutting quality. The slit width is narrow (typically 0.1--0.5mm), the precision is high (the general hole center distance error is 0.1--0.4mm, the contour size error is 0.1--0.5mm), and the surface roughness of the slit is good (generally Ra is 12.5--25μm) ), the slits are generally welded without further processing.
(2) Cutting speed is fast. For example, with 2KW laser power, the cutting speed of 8mm thick carbon steel is 1.6m/min; the cutting speed of 2mm thick stainless steel is 3.5m/min, the heat affected zone is small and the deformation is very small.
(3) Clean, safe and non-polluting. Greatly improved the working environment of the operators. Of course, in terms of precision and surface roughness of the slit, CO2 laser cutting is unlikely to exceed electrical machining; it is difficult to achieve flame and plasma cutting levels in terms of cutting thickness. However, the above significant advantages are sufficient to prove that CO2 laser cutting has been and is replacing some of the traditional cutting processes, especially the cutting of various non-metallic materials. It is an advanced processing method that is rapidly developing and widely used.
Since the 1990s, due to the development of China's socialist market economy and fierce competition among enterprises, each enterprise must correctly select certain advanced manufacturing technologies according to its own conditions to improve product quality and production efficiency. Therefore, CO2 laser cutting processing technology has achieved rapid development in China.