Grinding Mechanism,Force Prediction Model And Experimental Validation Of Vegetable Oil Based Nanofluids Minimum Quantity Lubrication

Nanofluid minimum quantity lubrication?NMQL?grinding is a new way of precision processing with high efficiency,low-energy consumption,cleaner and low-carbon use.The new technology can not only maximize the heat transfer ability and lubricating performance of MQL grinding,solve the technical bottlenecks of insufficient heat transfer ability of MQL,but also open up a new way for the application of MQL technology on grinding process of new and difficult-to-machine materials.However,from the perspective of grinding mechanism,there are the following mainly bottlenecks of NMQL grinding:the formation mechanism of oil film of vegetable oil in grinding zone,the evaluation system of physical properties of nanofluids on antiwear and antifriction as well as heat transfer mechanism,the mechanism of material removal in low and high speed grinding,the lubricating effects of NMQL on the mechanical behavior of abrasive cutting has not been solved,and to say nothing of realizing the active parameterized control on cooling lubrication performance in the application of the NMQL.Aiming at the bottlenecks in the application of the above technology,the processing mechanisms of NMQL grinding are studied in this paper,the influence mixed of nanoparticle MQL on the tribological and enhanced heat transfer characteristics in grinding zone are analyzed theoretically and experimentally,and the material removal mechanism and mechanical behavior in low and high speed grinding are also revealed.Based on the above,the grinding force prediction model is established.The main contents of the paper are as follows:1.The mechanism of cooling lubrication of vegetable oil based NMQL grinding is revealed.The influence law of different vegetable oils,physical properties and molecular structure of nanofluids on the film formation mechanism as well as antiwear and antifriction properties of grinding zone are studied.The heat transfer mechanism and influencing factors of nanofluids boundary layer in wheel/workpiece wedge-shaped space are analyzed.The evaluation system of the effect of vegetable oil based nanofluids on the cooling lubrication performance in grinding zone is established,which provides the theory evidence for the application of vegetable oil and NMQL.The grinding experiment of 45 steel workpiece material is carried out,and the grinding performance parameters of grinding force,specific grinding energy,grinding heat and workpiece surface roughness are observed to verify the influence rule.2.The influence rule of molecluer tructure on grinding mechanism is revealed.A new method for high temperature nickel-based alloys grinding with molybdenum disulfide?MoS₂?/carbon nanotubes?CNTs?mixed nanoparticles is proposed,and the effect of"physical synergism"of mixed nanoparticles on high temperature nickel-based alloy grinding and the enhanced heat transferare mechanism are revealed.The effect of the proportion of mixed nanoparticles on the phenomenon of"physical coating"is further explored and the optimal parameters of nanofluids are obtained.GH 4196 is used as workpiece to evalution the grinding performance of mixed nanoparticles.3.Based on the excellent performance of vegetable oil and mixed nanoparticles,a method of vegetable oil based NMQL grinding is further put forward,and the process optimization of high-temperature nickel-based alloy workpiece is carried out.The effects of concentration of nanofluids on the physical properties?viscosity,contact angle?of nanofluids are investigated.The surface morphology of workpiece characteristics is analyzed by means of autocorrelation analysis of workpiece surface morphology,and the influence trend of processing parameters on workpiece surface quality is quantitatively characterized.4.The material removal mechanism and basic mechanical behavior in wedge-constrained space of grinding wheel/workpiece are studied.A new grinding force prediction model based on material removal and plastic stacking principle is established.The kinematics mechanism of dynamic effective particle interference in grinding zone is revealed and the calculating formula of dynamic effective abrasive particle position and cutting depth is established.The precision prediction of grinding force under different lubrication conditions?dry grinding,MQL,NMQL?is realized based on single particle grinding force model.5.Aiming at high speed grinding process with different lubricating conditions,the kinematics formula and debris model of single abrasive interference material in grinding zone are established.The influence mechanism of velocity effect as well as lubrication effect on the deformation mechanism and strain rate of debris shear slip zone is revealed.The mechanism of debris formation and plastic accumulation under the combined influence of strain rate strengthening effect,strain hardening effect and thermal softening effect are analyzed.The effects of different grinding speed and lubrication conditions?dry grinding,MQL,NMQL?on the shape of debris,plastic stacking rate and grinding mechanical parameters are studied.