Study Of Multi-focus Lens Coaxial Water-jet Guided Laser Microfabrication System And Its Processing Performance

Compared with traditional laser processing technology,coaxial water-jet guided laser processing technology has the advantages of long processing distance,high processing accuracy,small heat affected zone and no obvious hot slag.It has broad application prospects in aerospace,precision manufacturing,biomedical and other industries.Although coaxial water-jet guided laser processing technology has such significant advantages,the key technologies are in the hands of western countries.At present,commercial coaxial water-jet guided laser processing equipment is not only expensive,but also blockades the technology of our country,becoming one of the "choke" technologies for our country.Although some universities and research institutes in China have studied the technology and equipment of water-jet guided laser processing,there has been no breakthrough in the key technical issues of processing power and efficiency,which limits the promotion and application of coaxial water-jet guided laser processing technology in China.Based on the discovery of "gas explosion" and the study of the causes of "gas explosion",this paper proposes a technical scheme that uses multi focus lens to replace single focus lens to solve the problem of gas explosion,thereby improving the power and processing efficiency of water-laser coupling laser,and carries out the key technology research of water-laser coupling system based on this technical scheme.At the same time,the micro water beam generation device and coaxial water-jet guided laser processing technology are deeply studied in this paper.The specific research contents are as follows:1.Study on the coaxial water-jet guided laser water-laser coupling machining system.The functional modules of the coaxial water-jet guided laser micro machining system are divided by the method of functional flow module division,and the development scheme of the coaxial water-jet guided laser water-laser coupling machining system is determined.A coaxial water-jet guided laser micromachining experimental system with the functions of laser focusing,micro water beam generation,water-laser coupling and precise movement was developed.Using Zemax optical analysis software,the simulation model of water-laser coupling is established,and the influence of static alignment deviation on the water-laser coupling efficiency and the energy distribution of the cross section of the water beam fiber is explored.Based on the principle of least square method,an image acquisition and processing program for water-laser coupling is developed,which reduces the alignment deviation of water-laser coupling and improves the water-laser coupling efficiency.2.Study on the water-laser coupling technology of coaxial water-jet guided laser with multi focus lens.Aiming at the key technical problems of the high-power underwater laser coupling device,such as the explosion of the nozzle and the inability of the water-laser coupling to continue,a large number of water-laser coupling experiments were carried out,and the phenomenon of "gas explosion" was found.The fundamental cause and mechanism of "gas explosion" are studied,and a technical scheme is proposed to replace single focus lens with multi focus lens to solve the problem of gas explosion and improve the power and processing efficiency of water-laser coupling laser.Based on the technical scheme,a four focus lens and corresponding water-laser coupling device were developed,and a large number of water-laser coupling experiments were carried out,which significantly improved the water-laser coupling laser power and the water-jet guided laser processing efficiency.The water-laser coupling laser power generated without gas explosion was increased from 120 W to 388 W,increasing by 223%.In this paper,the coaxial water-laser coupling model of multi focus lens is established by using optical simulation software,which provides the theoretical basis and simulation basis for the development of multi focus lens.3.Research on the micro water beam generator of coaxial water-jet guided laser.By using Fluent fluid analysis software,the velocity and turbulent kinetic energy distribution of the flow field in the coupling water chamber with different structures are simulated and analyzed,and the influence of the channel structure on the flow stability in the coupling water chamber is determined.By analyzing the attenuation law of velocity and turbulent kinetic energy on the axis of micro water jet,a theoretical basis is provided for determining the optimization of structural parameters of micro water jet nozzle.Based on the self-developed coaxial water-jet guided laser micro water beam generator,the stable length and impact of the water beam were detected.It was found that the stable length of the micro water beam obtained by the optimized nozzle increased by 4%,and the impact force increased by 16.9%.4.Study on coaxial water-jet guided laser processing technology of multi focus lens.The micro groove machining experiment of Ti-6Al-4V alloy was carried out by using a multi focus lens coaxial water-jet guided laser processing system.The influence of processing parameters on the machining morphology and surface roughness was analyzed.BBD design and response surface methodology were used to analyze the interaction of different processing parameters on micro groove depth,micro groove width and material removal rate.The established quadratic polynomial mathematical model can accurately predict the quality of the workpiece after machining.The experiment of cleaning the coating on the surface of metal substrate was carried out by using the coaxial water-jet guided laser processing system.The mechanism of removing the resin based coating on the surface of metal substrate by coaxial water-jet guided laser cleaning was revealed,and the mapping relationship between the cleaning process parameters and the cleanliness and roughness of the cleaned substrate surface was established.