Laser cutting machine is to melt and evaporate the workpiece with the energy released when the laser beam irradiates the workpiece surface, so as to achieve the purpose of cutting the workpiece. Laser cutting has many characteristics, such as high cutting precision, fast speed, no cutting pattern restrictions, automatic typesetting, saving cutting cost, smooth incision, low processing cost, etc. it will gradually improve or replace the traditional metal cutting equipment. So what are the perforation methods of laser cutting machine?
Cutting and piercing technology: any kind of thermal cutting technology, except for a few cases that can start from the edge of the board, generally must pierce a small hole in the board. Previously, in the laser stamping compound machine, a hole was punched with a punch, and then cut with a laser from the small hole. For laser cutting machines without stamping devices, there are two basic methods of perforation:
(1) Blast drilling: after the material is irradiated by continuous laser, a pit is formed in the center, and then the molten material is quickly removed by the oxygen flow coaxial with the laser beam to form a hole. Generally, the size of the hole is related to the thickness of the plate. The average diameter of the blasting hole is half of the thickness of the plate. Therefore, the hole diameter of the blasting hole for the thicker plate is large and not round, so it is not suitable to be used on the parts with higher requirements (such as the oil screen slotted pipe), but only on the waste. In addition, because the oxygen pressure used for perforation is the same as that used for cutting, the splash is large.
(2) Pulse perforation: (pulsedrilling) a small amount of materials are melted or vaporized by pulse laser with peak power. Air or nitrogen is often used as auxiliary gas to reduce the hole expansion due to exothermic oxidation. The gas pressure is smaller than the oxygen pressure during cutting. Each pulse laser only produces a small particle jet, which gradually deepens, so the perforation time of the thick plate takes a few seconds. Once the perforation is completed, immediately replace the auxiliary gas with oxygen for cutting. In this way, the perforation diameter is smaller, and its perforation quality is better than blasting perforation. Therefore, the laser used should not only have high output power; More importantly, the temporal and spatial characteristics of light beam, so the general cross flow CO2 laser can not meet the requirements of laser cutting.
In the case of laser cutting machine using pulse perforation, in order to obtain high-quality incision, the transition technology from pulse perforation when the workpiece is stationary to constant speed continuous cutting of the workpiece should be paid attention to. Theoretically, the cutting conditions of the acceleration section can usually be changed, such as focal length, nozzle position, gas pressure, etc., but in fact, it is unlikely to change the above conditions due to the short time. In industrial production, it is more realistic to change the average power of laser. The specific method is to change the pulse width; Change the pulse frequency; Change the pulse width and frequency at the same time.