| 7075 is a commonly used alloy of aluminum alloy,with the advantages of light weight,high strength,good toughness,tight structure and strong corrosion resistance,and is widely used in aerospace precision parts,automobile shape and important parts manufacturing and other fields.7075 aluminum alloy in the cutting process,due to high strength physical properties,resulting in the machining process of the machine tool spindle vibration abnormality,cutting force,sticking knife,vibrating knife,tool wear and processing surface quality is not easy to ensure and other factors affected,in order to make up for the lack of 7075 aluminum processing process parameters in the study,its process parameter optimization research significance.Based on this,this paper is based on the 7075 aluminum alloy CNC milling experiment,for high-quality and highperformance processing process parameter optimization research.Comprehensively analyze the cutting force,milling vibration and workpiece surface quality with the change of process parameters and give 7075 aluminum alloy optimized process parameters.The main research contents are as follows:(1)Preparations for milling experiments.VDF-850 A CNC machine tool is selected as experimental equipment,the experimental scheme is formulated,the milling method is determined to be smooth milling and dry one-way tooling,the experimental materials and tools are selected.(2)The experiment and analysis of milling force and milling vibration were carried out.The milling force and vibration characterization parameters were measured by Kistler9075 B measuring platform and DP700 dynamic signal analyzer.In order to study the variation law of milling force,milling vibration and surface quality with milling parameters,single-factor experiments and center composite multi-factor experiments based on response surface method were used for analysis,a polynomial model of milling resultant force and milling vibration was established and the obtained model fit,the results are good and meet the engineering requirements.(3)The surface roughness measurement and analysis were carried out.Mitutoyo SV-3100 surface roughness measuring instrument was used to measure the processed workpiece.The single factor experimental results show that the surface roughness decreases with the increase of the spindle speed and increases with the increase of the feed speed,milling depth and milling width.The change rule is explained by the principle of metal milling,the milling parameters are studied through the center composite multi-factor experiment results,combined with the multi-factor interactive response surface graph,and the surface roughness polynomial model is established.The model has good significance and meets engineering requirements.(4)The determination of the weight coefficients of each polynomial model is carried out.Using the combination of Analytic Hierarchy Process(AHP)and entropy weight method,the subjective and objective weight coefficients calculated respectively are brought into the multiplication and normalization combination weighting method,the subjective and objective combined weight coefficients of the milling resultant force,vibration and surface roughness model are obtained.(5)The parameter optimization of multi-island genetic algorithm was studied.Taking the spindle speed,feed rate,milling depth and milling width as the constraints,and the minimum milling force,the lowest vibration and the highest surface quality model as the optimization goals,the comprehensive objective optimization function model in the form of AHP-entropy weight method as the main and objective empowerment is established,and the parameter optimization is optimized by multiisland genetic algorithm,and the optimal 7075 aluminum processing combination process parameters are obtained. |
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