Studyon The Process Optimization Of Laser Cutting Galvanized Steel

Galvanized steel plates are widely used in car body because of its excellent corrosionresistance, while laser cutting technology will also be favored by the auto manufacturer forthe high quality, rapid speed and flexible processing. But up to now, systematic studiesabout the laser cutting technology on galvanized steel are quite less. Based on laser cuttingplatform designed by ourselves, laser cutting was carried out on galvanized steel plateswith a thickness of0.7mm in this study. The effects of the experimental parameters on thequality of laser cutting, such as laser power, cutting speed, distance between the nozzleand the sample surface as well as the assistant gas, were systematically analyzed. Kerfwidth, kerf roughness, lag thickness and striation were selected as evaluation criteria ofcutting quality. The influences of cutting parameters on the laser cutting quality weresynthetically analyzed.This study showed that laser power/cutting speed and pressure of assistant gas, otherthan the work distance, have a significant influence on the cutting quality.As laser power increases when other conditions remains unchanged,both theroughness and width of kerf accelerate at first and thenbegin to flatten. The striationbecomes clear and its striation depth grain increases. As the cutting speed increases, thekerf width appears to decrease slowly while kerf roughness trends to decline at first andthen increase. The striation becomes loose and its outline becomes much clearer.The auxiliary gas has a great effect on the quality of laser cutting, whichis presentedas follows. Firstly, the kerf roughness and width decreases slowly as the nitrogenpressureas assisting cutting increases.When the purity of nitrogen becomes higher,the kerfroughness becomes smaller, the changing degree of kerf width under different pressuresbecomes slower, and the striation morphology becomes more regular. Secondly, under thesame conditions, the minimum pressure of nitrogen is higher than that of oxygen, and theroughness and width of kerf as in cutting assisted by nitrogen are much lower than that incutting assisted by oxygen. At last, as the pressure increasesin cutting assisted by oxygen,the kerf roughness increases rapidly then declines and the kerf width increases quickly.The higher the purity of oxygen is, the more dramatic the changing level of the width androughness under different pressures is. The striation topographyin cutting assisted byoxygen is irregular, and it has an obvious protrusion and large fields. According to the regulation obtained in a single factor test, the process parametersshould be optimized on laser power, cutting speed, assist gas pressure. Process parametersof laser cutting can be achieved by designingan orthogonal test with three factors and fourlevels and analyzingexperimental results. Considering the quality, efficiency and its cost,the optimized parameters have been obtained as follows: nitrogen pressure of0.6MPa,cutting speed of39m/min, and laser power of2.5kW.A model of laser cutting process wasbuilt under Back Propagation usingexperimental data. The neural network will be built/trained and tested, which confirmedthat the prediction accuracy of the network met the requirements of industrial applications.