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Domestic sheet metal plate cutting obstacles encountered laser processing potential

  With the computer control technology and optical technology continues to progress, people for their processing capacity expectations are getting higher and higher, this expectation is not only able to cut, but also cut well and cut fast expectations. Laser processing as an advanced means of material cutting, has been more and more accepted by sheet metal producers.
  Laser processing started earlier in Europe and the United States and Japan, in the last century 80 years by the laser processing machine manufacturers of steel production put forward specific quality requirements, which have different from ordinary steel but the price of high laser dedicated steel. With the laser processing as the main means of cutting is accepted, 25mm following ordinary steel to laser professional materials as a standard material. However, due to the rapid development of China, steel production too late to adapt, there is the Chinese steel and imported steel points. The main difference is that the content of impurities in the steel and steel surface treatment and transportation and a series of reasons, resulting in the status of China's plate cutting difficult.
  China's crude steel production is not only the world's first, it is more than 50% of global production, developing countries and even some developed countries such as Australia and South Korea to save costs are also a lot of use of Chinese plate, so with its expectations of Chinese steel to adapt Laser cutting is not as good as research and proposing methods and proposals for quality processing of inferior materials. This article presents some of these considerations to initiate.
  [In the plate processing problems encountered]
  1. Carbon steel plate perforation problem
  In the thick plate processing perforation time accounted for a large proportion of the laser manufacturers have developed a rapid perforation technology, more representative of the high-energy perforation (hole), the advantages of this method is fast (1 second to t16mm For example - the same below), but the defect is not only affect the small shape of the processing, perforation into the huge energy so that the plate temperature rise and then affect the next overall cutting process. And perforation with a small power pulse, the time is very long (12 seconds), will lead to the efficiency of cutting and unit cost increase.
  2. Cutting surface quality problems
  Figure 1 and Figure 2 show the cutting section that is often encountered when machining a plate. Such cutting is not only questionable about the quality of the finished product, but also with the presence of overgrowth and severe sticky slag, Laser processing machine is different from the value of other cutting means.
  3. The whole board processing stability problem
  In the domestic steel processing of the whole board, there will often be local area of the phenomenon of poor processing. This phenomenon is sometimes very random, even in the case of good processing machine will appear. In order to deal with local failure products and greatly affected the progress of the work, here for this unexplained processing failure also gives some of the author's analysis and countermeasures proposal.
  Solution to the above problem
  1. Peak perforation (HPP) program
  As the name suggests is the use of a small duty cycle of the peak pulse laser, supplemented by spraying the material on the surface of the fuel to remove the edge of the hole attached to the control of the pulse of the reasonable frequency of cooling edge perforation. (3 seconds), but the perforation of the aperture is small (about φ4mm) and the edge of the hole without adhesion and lower heat, easy to the next normal cutting processing, compared to ordinary perforation The efficiency increased by 4 times. Figure 3 shows the difference between ordinary perforation, HPP perforation and high energy perforation.
  2. Cutting section improvement program
  An important factor in improving the cutting section for carbon steel is to control the heat of the plate and to ensure sufficient combustion of the laser beam. Mitsubishi Electric developed K-CUT processing conditions better completed this mission. Figure 4 is a comparison of the effects of cutting on conventional slabs with conventional conditions and K-CUT conditions. And for stainless steel is an important factor in improving the cutting section of the beam is improved (improve the depth of focus) and the effective use of auxiliary gas. Bright cutting technology is to improve the vibration and the nozzle of the results obtained. Figure 5 is the improved effect. Section of the upper part of the roughness of 8μ, the lower 12μ comparable to machining.
  3. To ensure the stability of the program
  In order to improve the speed of the processing machine, the laser machine uses the structure of the flying optical path, that is, the material tray does not move and the machining head moves in the whole machinable area. In order to compensate for the relative position of the processing head and the light source changes, the manufacturers also as much as possible to ensure that the spot in the processing range of consistency, the use of curvature variable refractor is a common choice. This method, although the structure is simple but will change the depth of focus, so that the focus is very sensitive to the thick plate cutting will become powerless (both to keep the spot unchanged but also to maintain the same depth of focus). Mitsubishi Electric used equal length optical way (in the range of processing within the light source and the processing head between the light propagation path equal length) to avoid the depth of change, so that the spot and focus are consistent. In addition to the emphasis on the heat of the plate to accumulate the heat to be controlled, a better solution to the stability problem. Figure 6 shows the principle of an equal length optical path and the processing effect at different locations in the machining area.