Fiber Laser Cutting Of Light-weight Alloy Sheets And Regression Analysis

Considering the energy conservation, emissions reduction and lightweight design requirements, light-weight alloys including aluminum(Al) alloys, tiantium(Ti) alloys and magenesium(Mg) alloys are widely used to replace traditional steel materials. Laser cutting is potential to improve the cutting quality of light-weight alloys becasused of high efficiency, high precise and excellent flexibility. However, few studies have been addressed on laser cutting of light-weight alloys. To deepen the understanding of this technique, this thesis investigates the process charaizations of laser cutting of AA2219 Al alloy, TC4 Ti alloy and AZ31 Mg alloy by employing a fiber laser. The main results are listed as follows.A series of expriments are carried out, and the effects of cutting parameters(laser power, cutting speed and laser defocus distance) on the kerf charsrstics(kerf width, root dross-height and kerf surface roughness) of the three alloys are obtained. In addition, the optimal range of cutting parameters are obtained according the experimental data. Under the optimal parameters, the kerf quality achieves the first standard.The regression analysis are employed to study fiber laser cutting of the three alloys. Both the two-order model and the exponential model are established. By contrasting the prediction precise, the matched model for each alloy are confirmed. Results show that the two-order model is more suitable in the regression of Al alloy, while the exponential model is more suitable in the regression of Ti alloy. For Mg alloy, the two-order model is more suitable in the regression of kerf width and root dross-height, while the the exponential model is more suitable in the regression of roughness.The generality of fiber laser kerf of Al alloy, Ti alloy and Mg alloy is that the kerf surfaces are grouped into three zones featured by different striation patterns from the upper to the bottom, which are horizontal striation zone at the upper, vertical striation zone at the middle, and oblique striation zone at the lower. The horizontal striation zone is the smoothest zone, while the oblique striation zone is the roughest zone. This generality is attributed to the own characteriations of laser cutting. The formation of the three striation zones on kerf surface is caused by the interaction between the gas pressure inside the cut and the other forces exerted on molten pool. In addition, the discrepancies on the kerf detals, such as the values of roughness and dross-height, are resulted from the different material properties of the three alloys.