Design of Laser Cutting Machine Nozzle and Air Flow Control Technology
Laser cutting machine nozzle design and air flow control technology Introduction: laser cutting machine laser cutting steel, oxygen and focused laser beam is sprayed through the nozzle to the material at the cut, thus forming a gas stream. Laser Cutting Machine The basic requirement for airflow is that the amount of air entering the incision is large and the velocity is high so that sufficient oxidation allows the exfoliation material to be sufficiently exothermic and that there is sufficient momentum to blow out the molten material. Therefore, in addition to the quality of the beam and its control directly affect the quality of cutting, the nozzle design and air flow control (such as nozzle pressure, the workpiece in the air position, etc.) is also very important factor. At present, the laser cutting nozzle with a simple structure, that is, Laser Cutting Machine a tapered hole with a small round hole. Usually by experiment and error method design. As the nozzle is generally made of copper, smaller, is vulnerable parts, often need to be replaced, so no hydrodynamic calculation and analysis.
In the use of the side of the nozzle from the introduction of a certain pressure Pn (gauge pressure Pg) of the gas, said nozzle pressure, from the nozzle outlet, a certain distance to reach the workpiece surface, the pressure that cutting pressure Pc, the last gas expansion to atmospheric pressure Pa. The study shows that as Pn increases, Laser Cutting Machine the airflow velocity increases and Pc increases.
Can be calculated using the following formula: V = 8.2d2 (Pg + 1)
V-gas flow rate L / min
D - nozzle diameter mm
Pg-nozzle pressure (gauge) bar
For different gases have different pressure threshold, when the nozzle pressure exceeds this value, the air flow is normal oblique shock, air flow from subsonic to supersonic transition. This threshold is related to the Pn, Pa ratio and the degree of freedom of the gas molecule (n): such as oxygen, air n = 5, so the threshold Pn = 1bar × (1.2) 3.5 = 1.89bar. When the nozzle pressure is higher Pn / Pa = (1 + 1 / n) 1 + n / 2 (Pn; 4bar), Laser Cutting Machine the normal flow of the airflow becomes a positive shock wave, the cutting pressure Pc decreases, the air velocity decreases The formation of eddy current on the surface of the workpiece, weakening the role of air to remove molten material, affecting the cutting speed. So the use of tapered bore with small round hole at the end of the nozzle, the oxygen nozzle pressure often 3bar or less.
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