Cylinder Craft Engraver-jk1215s

For different gases have different pressure threshold, when the nozzle pressure exceeds this value, the flow for normal shock wave, flow transition from subsonic to supersonic speed. This threshold and Pn, Pa ratio and gas molecules of degrees of freedom (n) related to two factors: such as oxygen, air n=5, so the threshold Pn=1barx (1.2) 3.5=1.89bar. When a higher nozzle pressure Pn/Pa= (1+1/n) at 1+n/2 (Pn;4bar), flow normal shock wave becomes a normal shock wave, cutting pressure Pc down, reduce the speed of air flow and Eddy current on the surface of the workpiece, weakens the effect of air removing molten material, effect of cutting speed. Conical hole small hole of the end of the nozzle and the nozzle of the oxygen pressure 3bar.

To further improve the speed of laser cutting, according to aerodynamics, increasing nozzle pressure does not produce a normal shock, designed and manufactured a type of zoom nozzle and Laval (Laval) nozzle. To facilitate the manufacturing structure that can be used in Figure 4. Germany University of Hanover Laser Center using 500WCO2 laser lens 2.5 ?, hole nozzle and Laval nozzle is tested separately, as shown in Figure 4. Test results are shown in Figure 5: represent the NO2, NO4, NO5, under different oxygen pressures, nozzles, cutting surface roughness Rz and cutting speeds Vc of relationship. As can be seen from figure NO2 hole nozzle Pn 400Kpa (4bar) cutting speed can only be achieved when 2.75m/min (carbon steel plate thickness 2mm). NO4, NO5, two Laval nozzle Pn 500Kpa to 600Kpa cutting speed of up to 3.5M/min and 5.5M/min. Should be noted that the cutting pressure Pc are artifacts and a function of the distance of the nozzle. Multiple reflections of boundary because of the oblique shock wave in the wind, the cutting pressure changes periodically.