Study On Magnetorheological Finishing Of Aluminum Alloy Optical Elements

With the continuous development of modern optical technology,metal optical elements represented by aluminum alloy materials have become an indispensable and important part in fields such as lasers,optical communication,and optical imaging.Singlepoint diamond turning can achieve rapid manufacturing of aluminum alloy optical elements,but the diffraction effect on the surface will reduce the performance of the optical elements.To achieve applications in visible and even ultraviolet wavelength bands,further polishing of aluminum alloy optical elements is required.Aluminum alloy material is a difficult-topolish material,and traditional polishing methods are difficult to produce aluminum alloy optical elements that meet high-quality requirements.As a new type of surface polishing technology,Magnetorheological finishing technology(MRF)has the advantages of high polishing efficiency,no wear of the polishing head,good polishing quality,stable polishing process,and low subsurface damage,which is very suitable for processing aluminum alloy optical elements.Currently,there is relatively little research on MRF technology for aluminum alloy optical elements in China,and the related theoretical and process systems are not yet mature.Starting from the characteristics of aluminum alloy materials,this project will systematically study MRF technology,and the specific research contents are as follows:Firstly,the applicable range of aluminum alloy materials under different preparation processes and processing methods was introduced,and the development history of MRF equipment was described.The control principle of the circulating control system for MR polishing fluid was also described.At the same time,the impact of process parameters on MRF was analyzed,and the role of removal function in the MRF process was elaborated,and the principles for selecting the removal function were given.Based on this,the overall research idea of this project was proposed.Secondly,starting from the constitutive model of MR fluid,the removal mechanism of MRF under macroscopic state was described based on the traditional interpretation of polishing.The dense particle flow theory was introduced to analyze the microscopic removal mechanism of MRF.At the same time,the theoretical modeling of the removal function in MRF was carried out,and the established model includes shape model of removal function,macroscopic removal function efficiency model,and microscopic removal function efficiency model.Then,based on the properties of MR polishing fluid and the characteristics of aluminum alloy materials,a single-factor experiment was conducted to control the composition of the polishing fluid,and the magnetorheological polishing fluid suitable for aluminum alloy materials was optimized.At the same time,the effect of the composition of the MR polishing fluid on the removal efficiency and surface roughness of aluminum alloy components was analyzed.The optimization experiments of process parameters for Magnetorheological finishing of aluminum alloy optical elements were carried out,and the process optimization ideas combining single-factor analysis method and Taguchi method were clarified,in order to determine the optimal process parameter combination and the ranking of the influence degree of process parameters.At the same time,the impact of process parameters on the removal efficiency and surface roughness of aluminum alloy elements was analyzed.Finally,optimization experiments were carried out on the MRF process parameters for aluminum alloy optical components.The process optimization idea combining single-factor analysis method and Taguchi method was clarified,and the optimal process parameter combination and the ranking of the influence degree of process parameters were determined.The optimal experimental plan for aluminum alloy components was proposed.Under the guidance of this plan,a MRF experiment was conducted on a RSA-6061 aluminum alloy flat mirror with a diameter of Φ100mm.After 45 minutes of polishing,the surface roughness was reduced from 8.619 nm to 2.715 nm.