Nozzle designLaser accessoriesSheet metal processingHardware accessoriesLaser cutting machineBending MachineLaser cutting machine Accessories
Nozzle design and air flow control technology: when laser cutting steel, oxygen and focused laser beam are emitted to the material to be cut through the nozzle, thus forming an air flow beam. The basic requirement for the air flow is that the air flow into the notch should be large and the speed should be high, so as to oxidize enough to make the notch material fully carry out exothermic reaction; at the same time, there is enough momentum to jet out the molten material. Therefore, in addition to the quality of the beam and its control directly affect the cutting quality, the design of the nozzle and the control of the air flow (such as the nozzle pressure, the position of the workpiece in the air flow, etc.) are also very important factors.Laser accessories
The nozzle for laser cutting adopts a simple structure, i.e. a conical hole with a small round hole at the end (as shown in Fig. 4). It is usually designed by experiment and error method. Because the nozzle is generally made of red copper, which is small and vulnerable, it needs to be replaced frequently, so the hydrodynamics calculation and analysis are not carried out. When in use, a certain pressure PN (gauge pressure PG) gas is introduced from the side of the nozzle, which is called nozzle pressure. It is ejected from the nozzle outlet and reaches the workpiece surface through a certain distance. Its pressure is called cutting pressure PC, and finally the gas expands to atmospheric pressure PA. The results show that with the increase of PN, the flow velocity and PC are increasing.Sheet metal processing
It can be calculated by the following formula: v = 8.2d2 (PG + 1)
V-gas flow rate L / min
D-nozzle diameter mm
PG nozzle pressure (gauge pressure) barHardware accessoriesLaser cutting machineBending
There are different pressure thresholds for different gases. When the nozzle pressure exceeds this value, the flow is a normal oblique shock wave, and the flow speed transits from subsonic to supersonic. This threshold value is related to the ratio of PN and PA and the degree of freedom (n) of gas molecules: for example, n = 5 of oxygen and air, so the threshold value PN = 1bar × (1.2) 3.5 = 1.89bar. When the nozzle pressure is higher pN / PA = (1 + 1 / N) 1 + n / 2 (PN; 4bar), the normal oblique shock wave seal of the air flow changes into a positive shock wave, the cutting pressure PC decreases, the air flow speed decreases, and eddy current is formed on the surface of the workpiece, which weakens the role of the air flow in removing molten materials and affects the cutting speed. Therefore, the nozzle with cone hole and small round hole at the end is adopted, and the nozzle pressure of oxygen is usually less than 3bar.MachineLaser Cutting
In order to further improve the laser cutting speed, according to the principle of aerodynamics, under the premise of increasing the pressure of the nozzle, there is no positive shock, so we can design and manufacture a zoom nozzle, namely Laval nozzle. The structure shown in Figure 4 can be used for the convenience of manufacturing. The laser center of the University of Hanover in Germany uses a 500wco2 laser with a lens focal length of 2.5 ″. Experiments are carried out with a small hole nozzle and a Laval nozzle respectively, as shown in Figure 4. The test results are shown in Fig. 5: the function relationship between the incision surface roughness Rz and the cutting speed VC of NO2, No4 and No5 nozzles under different oxygen pressures. It can be seen from the figure that the cutting speed of NO2 small hole nozzle can only reach 2.75m/min when PN is 400kPa (or 4bar) (the thickness of carbon steel plate is 2mm). The cutting speed of No4 and No5 Laval nozzles can reach 3.5m/min and 5.5m/min when PN is 500kPa to 600kpa. It should be pointed out whether the cutting pressure PC is a function of the distance between the workpiece and the nozzle. Because the oblique shock waves reflect at the boundary of the air flow many times, the cutting pressure changes periodically.
The first high cutting pressure zone is close to the nozzle outlet, the distance between the workpiece surface and the nozzle outlet is about 0.5 ~ 1.5mm, and the cutting pressure PC is large and stable, which is a commonly used process parameter in industrial production. The second high cutting pressure area is about 3 ~ 3.5mm of the nozzle outlet, and the cutting pressure PC is also large, which can also achieve good results, and is conducive to protecting the lens and improving its service life. Other high cutting pressure areas on the curve are too far away from the nozzle outlet to match the focusing beam.Machine Accessories
Carbon dioxide series: Carbon dioxide optical lens, excitation module, high pressure module, turbine, Focusing mirror, Bypos mirror, refractor, cutting head, nozzle, Ceramic Ring, dust cover
Optical fiber series: push in nozzle, Protective Lens, sapphire lens, ceramic ring, cutting head, cutting head accessories, ipg module, communication module, communication cable, protective cover , various filter elements, pressure reducing valve, Nozzle Body, quick-insert nozzle body, adaptor 2.0, servo, Motor , power supply, CNC rack, highyag cutting head, collimator Lens, focusing mirror and more.
Contact Now
