Research On Laser Paint Removal Technology And Device Based On Pulsed Fiber Laser

Laser cleaning has received extensive attention and achieved rapid development since the last century.Laser paint removal is a kind of widely used technology in laser cleaning.With its non-contact cleaning method,high efficiency,pollution-free and low cost,it has very important research value and development potential in many areas of industrial processing.In this dissertation,which analyzes the process of laser paint removal,simulates the model of paint removal and conducts comparative verification through experiments,finally obtains the best parameters.The results of the study will help guide to select cleaning parameters that remove different coatings.The mobile paint removal device,which is designed in this paper,promotes the industrialization process.1.In this dissertation,the laser paint removal technology and its principle is studied theoretically,which mainly analyzed two mechanisms and the interaction between laser and material.According to the principle of ablation effect and vibration effect,the theoretical basis for paint removal are T₁?27?T?0,t??27?T₂,₁F>F?.₁T,T?0,t?and ₂T are the gasification temperature of paint layer,the temperature of the paint surface and the melting point of substrate.₁F and F?are the paint release force and the adhesion of the paint layer,respectively.2.The laser paint removal model is constructed based on ablation mechanis m,which has two absorptive layers and is more accord with practical situations.The thermal process of laser in each layers is analyzed through this model.The software of ANSYS was used to simulate the process of laser paint removal,and The model was solved to obtain the temperature distribution of paint surface when laser heat clean the mold,and temperature change curve under different laser energy density and scanning speed.Finally,the linear equation between laser energy density and maximum temperature of paint surface was obtained by a series of data.The theoretical energy range required to remove the 40?m red paint layer was 164.13 J/cm² to 176.07 J/cm²,and the damage threshold was 253.66J/cm².3.Experiments were done to study the laser cleaning technology.The energy density,scanning speed,and line width to the impact of cleaning effect was gained using data and results.The laser used in experiment has a maximum output power of 200 W,2-50 kHz adjustable repetition rate,a maximum single pulse energy of 10 mJ,the focus spot of 0.05 mm.The thickness of the paint before and after the cleaning was measured by thickness gauge,and the percent of paint removal was calculated.The surface morphology of the cleaned sample was observed by metallographic microscope.The results show that,for the paint with a thickness of 40?m on the steel substrate,the paint removal effect was the best under the value of energy density was 176.11J/cm²,the substrate damage was serious when the energy density was 240.97J/cm².It is very close to the theoretical value and verifies the accuracy of this experimental results.The scanning speed and line width affect the overlap of laser spot in the X and Y directions,which more than ratio of 80%is effective to remove the paint while keeping the substrate undamaged.The corresponding line width is 0.01 mm,scanning speed is 200 mm/s under the repetition rate of 20 kHz,these two values can be adjusted according to the beam diameter and laser parameters.4.A mobile laser cleaning device was designed based on the application of paint removal,which is suitable for large area paint and rust removal.It adopts a separate structure of cabinet and handheld laser processing apparatus,which is easy to carry and operate.The cleaning efficiency is up to 6m²/h and the maximum output power is 200W.In the system,the working status of the whole machine is controlled by the PLC module,and the scanning length of laser beam can be adjusted according to the sample of different shapes and positions.