Perforated cutting techniques: any kind of thermal cutting technology, except in a few cases from the outside edge, generally must put a small hole on the Board. Earlier laser stamping machine is washed with punch out a hole, and then use the laser starts from the small hole for cutting. For laser cutting machine without a stamping device there are two basic methods of perforation:
(1) blasting perforation: (Blast drilling), treated by continuous laser irradiation in the Center to form a crater, and the oxygen flow with coaxial laser beam will soon melt material removed to form a hole. Related General size and thickness, blasting perforation average diameter is half the thickness, so the thicker plate blasting perforation apertures larger and not round, should not be used on the demanding parts (such as slotted tube of oil), can only be used on waste. Due to a hole in the oxygen pressure and cutting the same large splash.
(2) pulse perforations: (Pulse drilling) with a high peak power pulsed laser makes a small amount of material melting and vaporization, usually air or nitrogen as a secondary gas in order to reduce the exothermic oxidation of hole expansion, when the gas pressure is cutting oxygen pressure. Each produces smaller particles by pulsed laser jet, deepening and perforated plate in a few seconds. Once the piercing is completed, immediately replaced the auxiliary gas oxygen for cutting. Smaller diameter perforation, perforation of the quality is better than blasting perforation. The lasers that are used should not only have a high output power; more importantly time bunch of time and space characteristics of cross flow CO2 laser therefore cannot meet the requirements of laser cutting.
In addition, perforation of the pulse also has a reliable pneumatic control system, with the gas type, pressure switch and perforated time control. In the case of perforation of the pulse, in order to obtain high quality cut, from the rest of the workpiece, such as perforation of the pulse to the workpiece speed transitions of continuous cutting technology should pay attention to. Theoretically can usually be changed to speed up the cutting conditions: such as focal length, location of nozzles, gas pressure, but because there is little possibility of too short a time to change these conditions. Major changes in the industrial production laser average power means more realistic, there are three: (1) change the pulse width and (2) changing the pulse frequency; (3) changes the pulse width and frequency. Actual results indicate that paragraph (3) work best.