| It is inevitable to use paint to protect metals in daily life and industrial fields.But when the metal has been working for a long time,the paint will gradually fall off and cannot protect the metal.Therefore,the original paint layer must be completely removed before spraying a new paint layer.As a new type of non-contact surface pollutant removal technology,laser cleaning has the characteristics of high efficiency,environmental protection,and high accuracy.It is gradually applied in the industrial field.Aiming at the efficient removal of acrylic polyurethane paint on the surface of5083 aluminum alloy by fiber pulse laser without damaging the substrate,this paper studies the theoretical mechanism of laser paint removal,simulates the process of pulse laser paint removal,and finally compares it with simulation through experiments verify and get the best cleaning parameters.The main research contents are as follows:(1)The characteristics of the laser as a cleaning light source and the heat conduction model of laser energy between the paint layer and the substrate are studied,the partial differential equation of heat conduction is analyzed,the analytical solution of the heat conduction equation is solved,and the laser energy is obtained on the substrate and surface of the material.The depth law of the effect of the lacquer layer.The theoretical mechanism of laser paint removal was discussed,and a theoretical model of pulsed laser paint removal was established.(2)Using COMSOL multiphysics software,a numerical model of fiber pulse laser cleaning of the surface paint layer of 5083 aluminum alloy was established,and the effects of lasers of different powers on the temperature field distribution and cleaning depth of the aluminum alloy surface paint layer,as well as the spot overlap rate were explored.The effect on the cleaning effect is the laser power that can prevent the surface of the substrate from being damaged,and can also completely remove the paint layer material,and the spot overlap rate that can obtain a good cleaning effect,providing theoretical guidance for subsequent experimental research.(3)The experiment of pulsed laser cleaning of acrylic polyurethane paint on the surface of 5083 aluminum alloy was studied,and the influence of different laser parameters on the micro morphology,roughness,cross-sectional microstructure and cross-sectional hardness of the cleaned sample was analyzed.The results show that the pulsed laser will leave 50?m pits on the surface of the sample for cleaning.When the laser energy density is 15.587J/cm~2,the power is 30W,and the spot overlap rate is50%,it can make the paint on the surface of the sample is completely removed without damaging the surface of the substrate,and the roughness of the sample after cleaning under this parameter is the lowest compared to before cleaning,which is4.48?m.After cleaning,the hardness of the area near the cleaning layer on the sample surface ranges from 65 to 75 HV,while the hardness before cleaning is 46 to 60 HV,and the hardness increases by about 30%after cleaning,The tensile and bending properties of 5083 aluminum alloy substrate were not significantly affected before and after pulse laser cleaning. |
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