CO₂Laser Cutting Of Thick Low-carbon Steel

With the development of Construction Machinery field, laser cutting of thick lowcarbon steel becomes more and more important. However, with the increase of steel platethickness, it’s difficult to cut thick metal steel by laser cutting due to the much drossattachment, side burning and thick stripes. In terms of the present domestic situation, laserpower of domestic laser machine is generally within the scope of2000W to4000W, andthe ordinary laser machine is equipped with a conventional converging nozzle. Therefore,the use of low-power CO₂laser with a conventional converging nozzle to cut the thicksteel is very necessary.In this study, laser cutting was carried out on low carbon steel plate with a thickness of20mm. First, experiments were carried out by only varying one of the cutting processparameters while keeping the rest at constant values to study the effects of input processparameters on cut quality including nozzle diameter, focal point position, oxygen pressure,cutting speed, nozzle standoff distance, laser power. Kerf width, heat affected zone,surface roughness, striation and dross attachment were selected as criteria of cuttingquality. The influences regulation of cutting parameters on the laser cutting quality weresynthetically analyzed. At the same time, we also investigated that the tape of kerfcomparing to the kerf tape of thin sheet and the number of stripes in the zone which within2-5mm distance to the upper kerf for the effects of laser cutting quality.Through the effects of6process parameter for laser cutting quality, it indicated that4cutting parameters which had a greater impact on the cutting performance including laserpower, cutting speed, oxygen pressure, focal point position. Four factors and three levelsorthogonal experimental was performed to determine the optimal parameter of lasercutting of20mm-thick low carbon steel plate. After range analysis and verification test, wegot optimization parameters respectively corresponding to the minimum kerf width,minimum HAZ width and minimum surface roughness. In order to verify optimal parameter on the basis of the orthogonal test, we investigated the laser curve plate cuttingof different radius of circular arc and different angle corner cutting. The optimal parameterhad a good quality for curve and corner cutting.