Research On Pulsed Laser Cleaning Of Cessna 172 Engine Casing

Continuous airworthiness maintenance is a remanufacturing process of aircraft and a means to maintain and restore the initial airworthiness level and inherent reliability of aircraft.In the process of aero-engine maintenance,the casing surface needs to be cleaned to ensure the reliable operation of the engine.Currently,traditional cleaning methods have drawbacks such as low efficiency,serious pollution and health hazards,which cannot meet the requirements of green and intelligent development in the field of civil aviation maintenance.In contrast,laser cleaning technology is favored because of the characteristics of"green,environmental protection,efficient and controllable".The application scope has covered medical treatment,cultural relics,aerospace,ships,automobiles,high-speed rail and so on.This paper mainly studied the engine accessory casing of Cessna 172 aircraft,which is widely used in general aviation.Aiming at the cleaning requirements of the surface layer and contaminated layer of Cessna 172 aircraft engine casing,this paper explored the influence of laser process parameters on the cleaning effect of the casing surface.The optimal laser process parameters for removing different adhesion layers on the casing surface were obtained,and the surface quality of the casing after cleaning was evaluated comprehensively,in order to form the suitable technical conditions and equipment for laser cleaning on the casing surface.First of all,according to different types of adhesive layers on the surface of the cartridge and the main process parameters of laser cleaning,orthogonal experiments and single factor experiments were designed in this paper.By analyzing the surface microstructure,roughness and cleanliness of the laser cleaning area of the cartridge,the influence rules of different laser parameters on the cleaning effect of the cartridge surface were explored.To find the optimal laser process parameters for removing different adhesion layers on the casing surface.The results show that the influence degree of laser process parameters on the cleaning effect of casing surface coating is as follows:average laser power,scanning speed,scanning line spacing;The laser energy density of 18.33 J/cm~2 and scanning speed of 1600 mm/s are the best paint removal parameters.The influence degree of laser process parameters on the cleaning effect of contaminants on the surface of the casing is successively as follows:scanning speed,average laser power,scanning line spacing;The laser energy density of 6.11J/cm~2 and scanning speed of 2000 mm/s are the best cleaning parameters for the pollutants on the surface of the casing.The research results provide data reference for the application of laser cleaning technology in aircraft engine casing.Secondly,in order to ensure the safety of the casing substrate while obtaining the ideal process parameters,the surface quality,microhardness,roughness and other corresponding surface properties of the casing after laser cleaning were comprehensively evaluated and verified.The results show that,for the removal of paint layer on the casing surface,under the action of the optimal laser paint removal process parameters,the substrate itself is not damaged,and the paint removal rate can reach 98.7%.Compared with the original surface of the casing,the surface microhardness increases by 1.9%,the surface roughness S_a is 2.48μm,and the surface free energy increases by 36.2%.It is beneficial to repainting the casing surface.In addition,the pollutants on the casing surface can be effectively removed under the optimal laser parameters,and the substrate surface is not damaged.Compared with the original surface of the casing,the surface roughness S_a is 2.73μm,the corrosion resistance is improved,the surface microhardness is increased by 6.6%,the surface free energy is reduced by 23.3%,and the hydrophobicity is maintained,meeting the quality requirements of the casing surface cleaning.Finally,this paper systematically analyzed the practical engineering application requirements of Cessna 172 aircraft engine casing surface cleaning and the requirements for each component of laser cleaning equipment.The system modules of the equipment are designed and selected,the software and hardware modules were optimized and integrated,and a set of portable laser cleaning equipment was designed.After the assembly and testing of the whole system,it can effectively removed the paint and pollution layer on the surface of the object,achieve the desired cleaning effect,and achieve the performance requirements of the whole machine.The integrated portable laser cleaning equipment improves the shortcomings of the existing equipment,such as complex operation and limited cleaning format,and makes the laser cleaning more intelligent and more convenient to use in actual industrial production.The research results have formed a high quality non-destructive cleaning technology and equipment for engine casing surface,which is helpful to provide technical support for the development of laser cleaning engineering application in aero-engine manufacturing and remanufacturing.