In the general thermal cutting technology, only a few cases cut directly from the edge, and most of them are perforated on the board first. For example, the early laser stamping compound machine used punches to punch holes first, and then laser cutting, but how to punch holes for laser cutting machines without punching devices? Let’s take a look at the experience summarized by professional small laser cutting machine manufacturers.
Pulse perforation technology is a pulsed laser with high peak power. First, a small amount of material or the surface of the material is melted or vaporized, and air or nitrogen is used as an auxiliary gas to reduce the expansion of pores due to exothermic oxidation. The gas pressure is lower than Oxygen pressure during cutting. Each pulse laser only produces small jets of particles, which penetrate slowly, so the perforation time of thick plates is longer than that of thin plates, about a few seconds. When the perforation is completed, the auxiliary gas is immediately replaced with oxygen for cutting work. In this way, the diameter of the perforation is small, and the perforation quality is better than that of blasting perforation. The lasers used in this process require high power output, and the time and space characteristics of the beam are also very important. Cross-flow CO2 lasers cannot meet this laser cutting requirement. Another important aspect of pulse perforation is the configuration of the gas circuit control system. It is necessary to ensure good control of the gas type, gas pressure cutting and perforation time.
Another perforation technology is blasting perforation. After continuous laser irradiation, a pit is formed in the center of the plate. The coaxial oxygen flow of the laser beam quickly melts the material to form a hole. Generally, plates of different thicknesses need to be equipped with different laser powers for cutting. machine, the average diameter of blasting perforation is half of the plate thickness, so blasting perforation for thicker plates will result in a larger perforation diameter, and it is not recommended to use blasting perforation technology for workpieces that require high processing accuracy. The same as the oxygen pressure during cutting, it will cause obvious splash, so pay attention to safety.
In order to obtain high-quality cutting in the case of small laser cutting machines using pulse perforation, the transition technology from pulse perforation when the workpiece is stationary to constant-speed continuous cutting of the workpiece should be paid attention to. In theory, by changing the cutting conditions of the acceleration section, such as the focal length , nozzle position, gas pressure, etc. In fact, it is unlikely to change the above conditions, because the time is too short. In industrial production, it is generally realized by changing the average power of the laser, and small laser cutting machines improve the cutting quality by changing the pulse width and pulse frequency.