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Laser cutting machine "those things"

  Laser in the teaching, military, industrial applications. One of the laser cutting machine is one of its applications. Laser cutting machine in the metal and non-metallic cut on the use. The surface of the material is melted by the laser beam. This article will talk about the principle of laser cutting machine.

  Principle of Laser Cutting Machine - Introduction
  Laser cutting machine technology uses the laser beam to the surface of the metal plate when the release of energy. The metal sheet is melted and the slag is blown away by the gas. Since the laser power is very concentrated, only a small amount of heat is transferred to other parts of the sheet metal, resulting in a small or no deformation. The use of laser can be very accurate cutting complex shape of the blank, the cutting of the blank need not be further for further processing.
  Laser source generally use carbon dioxide laser beam, the working power of 500 to 5000 watts. The power level is lower than the power required for many home heating, and the laser beam is gathered in a small area due to the lens and the mirror. A high concentration of energy can be carried out rapid local heating, so that the metal plate to melt.
  The use of laser cutting equipment can cut 16mm below the stainless steel, add oxygen in the laser beam can cut 8 ~ 10mm thick stainless steel, but after the oxygen cut in the cutting surface to form a thin oxide film. The maximum thickness of the cut can be increased to 16mm, but the size of the cutting part of the larger error.
  As a high-tech laser technology, since its inception, has been for different social needs for the development of various industries for laser products, such as laser printers, laser beauty machine, laser marking CNC laser cutting machine, laser cutting machine and other products, As the domestic laser industry started late, in technology research and development on a large extent lagged behind in some developed countries, the current domestic laser products manufacturers to produce laser products, some key parts such as laser tube, drive motor, galvanometer, focus Mirror, etc. or use the goods. Which led to the rise in costs, but also increased the consumer's commitment.
  In recent years, with the progress of domestic laser technology, machine and some spare parts in the R & D and production has gradually moved closer to foreign advanced products. In some ways even better than foreign products, coupled with the advantages of the grid, in the domestic market or dominate. But in some precision machining and equipment, stability and patience, foreign advanced products or occupy an absolute advantage.
  Principle of laser cutting machine - principle
  In the laser cutting machine, its main work is the laser tube, so we have to understand the laser tube.
  Are clearly aware of the laser equipment, the importance of laser tube, the following is now the most common of a laser tube to determine. CO2 laser tube!
  The composition of the laser tube is made of a hard glass and is therefore a fragile, cracked material. To understand the CO2 laser tube, we must first understand the structure of the laser tube, like this kind of carbon dioxide laser are used in the sleeve structure, the most inside is a layer of discharge tube. However, the diameter of the laser discharge tube of the carbon dioxide is brighter than that of the laser tube itself. The thickness of the discharge tube is proportional to the diffraction effect caused by the size of the spot. The length of the tube length is proportional to the output power of the discharge tube. The proportion of.
  Laser cutting machine in the course of operation, the laser tube will produce a lot of heat, affecting the normal work of the cutting machine, so the need for special field chiller to cool the laser tube to ensure that the laser cutting machine in the thermostat state of normal work. 200W laser selection CW-6200 on it, the cooling capacity of 5.5KW; 650W laser to use CW-7800, cooling capacity can reach 23KW.
  Laser cutting machine principle - cutting characteristics
  Advantages of laser cutting:
  Advantages I - high efficiency
  Due to the transmission characteristics of the laser, laser cutting machine is generally equipped with multiple CNC table, the entire cutting process can be all CNC. Operation, just change the NC program, you can apply different parts of the cutting, both two-dimensional cutting, but also to achieve three-dimensional cutting.
  Advantages II - fast
  Power of 1200W laser cutting 2mm thick low carbon steel plate, cutting speed up to 600cm / min; cutting 5mm thick polypropylene resin board, cutting speed up to 1200cm / min. The material does not need to be clamped during laser cutting.
  Advantages III - good cutting quality
  A: laser cutting incision narrow, parallel to both sides of the slit and perpendicular to the surface, cutting parts of the dimensional accuracy of up to ± 0.05mm.
  2: cutting the surface smooth and beautiful, the surface roughness of only a few tens of microns, and even laser cutting can be used as a last process, without mechanical processing, parts can be used directly.
  After the laser cutting, the width of the heat affected zone is very small, the performance of the material near the slit is almost unaffected, and the workpiece deformation is small, the cutting precision is high, the geometry of the slit is good, and the cross section shape of the slit is Regular rectangle. Laser cutting, oxyacetylene cutting and plasma cutting methods are shown in Table 1, cutting material is 6.2mm thick low carbon steel plate.
  Advantages IV - cutting non-contact
  Laser cutting when the torch and the workpiece is not in direct contact, there is no tool wear. Processing different parts of the shape, do not need to replace the "tool", just change the laser output parameters. Laser cutting process low noise, small vibration, small pollution.
  Advantages Ⅴ - cutting materials and more
  Compared with oxyacetylene cutting and plasma cutting, laser cutting materials, including metal, non-metallic, metal and non-metallic matrix composites, leather, wood and fiber.
Laser cutting machine principle - cutting method
  Ⅰ vaporization cutting
It is meant that the removal of the material to be processed is carried out mainly by vaporizing the material.
  In the process of vaporization, the workpiece table and under the action of the focused laser beam, the temperature quickly rises to the vaporization temperature, the material is vaporized in large quantities, and the high pressure steam is formed by supersonic outward injection. At the same time in the laser area to form a "hole", the laser beam in the hole several times to reflect the material and the absorption of laser abundance of rapid increase.
  During high-pressure steam jetting, the melt in the slit is blown away from the slit at the same time until the workpiece is cut off. Within the vaporization of cutting mainly rely on the way the material vaporization, so the required power density is high, generally should reach 10 square kilometers per square centimeter above the square.
  Vaporization cutting is a method of laser cutting some low-ignition materials (such as wood, carbon and some plastic) and refractory materials (such as ceramics, etc.). When cutting the material with a pulsed laser, the method of vaporization is also used.
  Ⅱ reaction melting cutting
  In the case of melt cutting, if the auxiliary gas stream is not only blown away from the melt in the slit, but also with the workpiece to heat up the reaction, so that the cutting process to increase the other - heat source, such a cut called reactive melting cutting. The gas that normally reacts with the workpiece is oxygen or a mixture of oxygen.
  When the surface temperature of the workpiece reaches the ignition temperature, a strong combustion exothermic reaction occurs, which greatly improves the ability of laser cutting. For low carbon steel and stainless steel, the energy provided by the combustion exothermic reaction is 60%. For active metals such as titanium, the energy provided by combustion is about 90%.
  As a result, the reactive melting cut is required to have a lower laser power density of less than 1/20 of the vaporization cut, and 1/2 of the melt cut, as compared to laser vaporization cutting, like melting. However, in the reaction melting cutting, the internal combustion reaction will cause some chemical changes on the surface of the material, which will affect the performance of the workpiece.
  Ⅲ melt cutting
  In the laser cutting process, if the addition of an auxiliary blowing system with the laser beam coaxial, so that the removal of the melt during the removal process is not solely on the material vaporization itself, but mainly rely on the high-speed auxiliary air blowing effect, the melt Continuously blowing away from the slits, such a cutting process known as melting cutting.
  During the melt cutting process, the workpiece temperature no longer needs to be heated above the vaporization temperature, so the required laser power density can be greatly reduced. From the latent heat ratio of the material melted and vaporized, the laser power required for melt cutting is only 1/10 of that of the vaporization cutting method.
  Ⅳ laser scribing
  This method is mainly used for: semiconductor materials; the use of high power density of the laser beam in the surface of the semiconductor component workpiece to draw - a shallow trench, because this groove weakened the bonding strength of semiconductor materials. The method or vibration of the method to break it. The quality of the laser scribing is measured by the size of the surface debris and the heat affected zone.
  Ⅴ cold cutting
  This is a new type of processing method, with the recent years of ultraviolet band high-power excimer laser and the emergence of the proposed. Its basic principle: the energy of ultraviolet photons with many organic materials can be similar to the combination of high-energy photons to hit the organic material with the bond and break it. So as to achieve the purpose of cutting. This new technology has a broad application prospects, is not in the electronics industry in the application will be very wide.
  Ⅵ thermal stress cutting
  The brittle material is heated under the laser beam, and its surface is liable to produce a large stress, so that it can be tended to be broken by the stress point of the laser heating. This cutting process is called laser thermal stress cutting. The mechanism of thermal stress cutting is that the laser beam heats a certain area of ​​the brittle material to produce a significant temperature gradient.
  The workpiece surface temperature is higher to occur, while the workpiece temperature is low to hinder the expansion of the workpiece surface, resulting in tensile stress on the inner surface of the radial extrusion stress. When the two stresses exceed the breaking strength of the workpiece itself. It will crack on the workpiece. So that the workpiece is broken along the crack. Thermal stress cutting speed - the stock is m / s order of magnitude. This cutting method is suitable for cutting glass, ceramics and other materials.
  Summary: Laser cutting machine is the use of laser characteristics and focus on the lens to focus on the material surface melting or gasification of a cutting technology. Can do cutting quality, fast, cutting materials and more efficient.