MQL Processing Characteristics And Experimental Research Based On Nano Additive

Minimum Quantity Lubrication(MQL)processing,as a green processing technology,is becoming more and more widespread.Spraying micro degradable lubricating oil can achieve a large number of cutting fluid.The key of the oil is lubricant and additives.In this study,numerical calculations and experimental verification methods were used.Nano-graphene and nano-copper powders were used as additives,and oleic acid and linoleic acid in vegetable oils were used as base oils to explore the characteristics of micro-lubrication in cutting processing.The main work is as follows:(1)Relevant literatures of MQL processing technology were reviewed firstly.Then the lubrication mechanism of MQL and related knowledge of vegetable oil were stated.By analyzing the lubrication of vegetable oil and additives during the cutting process,the main factors influencing the lubrication effect were proposed finally,including the adsorption energy of fatty acid molecules,the sub structure and the content ratio of nano additives.(2)Useing the Material studio7.0 molecular dynamics software,the adsorption and the shear on the Fe(110)surface were simulated at different propotions of oleic acid and linoleic acid.The surface binding energy of the molecules with the metal substrate and the distribution of the friction coefficient and the molecular concentration were obtained.Results show that the lubrication effect of oleic acid is better than that of linoleic acid.(3)Adsorption and shear simulation with different proportions of oleic acid,linoleic acid and nano additive(graphene and copper)were performed.It's obvious from the simulation that nano copper powder can enhance the adsorption of oleic acid and linoleic.Besides,nano copper particles are more prone to sink than graphene.Effects of the shear rate,pressure,proportion of mixed oil and additive content on shearing were analyzed and the best combination of above-mentioned parameters was achieved through the orthogonal experiment.(4)A MQL turning experiment system was built.First the turning experiment on 45 steel was carried out using single factor method under different test conditions of vegetable oil 2000,oleic acid/linoleic acid(1:1.5)and corn oil.With the changing of cutting speed and feed rate,the corresponding changing regulations of main cutting force,surface roughness and cutting temperature were obtained.Furthermore,the L16(4~4)orthogonal cutting experiment(Related experimental parameters were consistent with simulation)was carried out.Effects of cutting speed,feed rate,the proportion of oleic acid/linoleic acid and the mass fraction of nano additive on the main cutting force,surface roughness and cutting temperature were analyzed.The best parameters were obtained.Experiment results were basically consistent with simulation results.Finally,the L16(4~3)orthogonal experiment was carried out using corn oil as the base oil,whose results show that the esters and other fatty acids in the corn oil have little effect on the best nanoscale content.This reaearch is the part of National major projects"High-speed CNC cutting process monitoring and evaluation method"(No.2013ZX04009031-4),which revealled the mechanism of micro lubrication and achieved the best formulation of the lubricating oil and additives.It helps to further enrich and develop the theory of metal cutting and provide a reference basis for enterprises'production.