Research On Fabrication Of Precision Micropores By Ultrashort Pulsed Laser

Aerospace industry belongs to the national security industry.Machinery industry,electronics industry and automobile industry are pillar industries and high-tech industries in China.With the development of industrial manufacturing technology,the performances of aero-engine and motor vehicle nozzles have been continuously improved.Many new grouped holes have been adopted in the design.These micro-holes are required to have high precision,good surface and side wall quality,no recast layer and micro-cracks.In the face of these technical requirements,traditional EDM and machine are required.The machining methods of machine lathes and millisecond nanosecond laser drilling technology have gradually failed to meet the requirements.On the basis of traditional microporous fabrication technology and existing laser drilling technology,a new laser microporous fabrication technology is proposed in this paper.The technology of ultra-short pulse laser for high antimetal material is studied theoretically and experimentally.The mechanism of interaction between ultra-short pulse laser and material is discussed and analyzed.Through various comparative experiments,ultra-short pulse laser is selected as the final choice.A rotating light system based on Dove prism is proposed to break through the limitations of traditional impact drilling and general galvanometer scanning optical rotation.Firstly,through the theoretical analysis of the laser-material interaction and the experimental results,the mechanism of the light-material interaction and the law of surface quality change are analyzed;the principle and limitations of laser-impacted drilling are revealed through experiments,and the traditional micro-hole processing methods are compared,such as EDM drilling,nanosecond laser drilling and so on.The superiority of rotary drilling in comparison with percussive drilling is analyzed through experiments.Secondly,the limitations of the existing optical rotation drilling,especially the galvanometer scanning drilling technology,are revealed through experiments.The Dove prism optical rotation drilling system is proposed.The principle and advantages of optical rotation are obtained through theoretical analysis,and the possible systematic errors are corrected and analyzed.Thirdly,the effects of single pulse energy,laser repetition frequency,spot rotation speed,polarization direction,focus position and assistant means on hole-making efficiency are studied by using a 15 picosecond pulse laser combined with the mechanism of picosecond laser and material interaction.The research shows that laser drilling is affected by many factors,and these factors need to be considered comprehensively in the preparation of micro-holes.Based on the above three points,a set of ultra-short pulse optical rotation system with high quality micro-pore preparation was built.With the aid of auxiliary means,high quality and controllable drilling technology was realized for specific materials such as sapphire,borosilicate glass and 304 stainless steel.