Surface Formation Mechanism And Experimental Study Of Mixed Nanofluid Minimum Quantity Lubrication And Multi-angle Ultrasonic Vibration Coupling Grinding

Green development of manufacturing industry is an international trend.Reducing the use of a lot of grinding fluid in machining operations especially grinding,avoiding environmental and healthy problems from the root causes,and developing the clean,efficient and low carbon grinding technology has become necessary conditionsof green manufacturing.Nanofluid Minimal Quantity Lubrication?MQL?grinding inherites all theadvantages and solves the heat transfer problemof MQLgrinding.It is a kind of green and environment-friendly,efficient and economical grinding technology.However,the single nanoparticles can not have good lubricating and cooling performances at the same time,and Nanofluid MQL can not actively control the micro-morphology of the workpiece surface.According to the above problems,the research work of the coupling grinding of Al₂O₃/SiC mixed nanofluid MQL and multi-angle two-dimensional ultrasonic vibration was carried out.The effects of concentration of mixed nanofluids and different physical coating phenomena on grinding force and surface morphology in MQL are studied in this paper,and the optimization of jet parametersis analyzed in this paper.The variation of elliptical orbit of ultrasonic vibration at different angles was obtained by matlab simulation.Then the mechanism of effects of elliptical orbit at different angles on the surface morphology of multi-angle two-dimensional ultrasonic vibration grinding were analyzed..Finally,the surface formation mechanism of micro lubricating grinding of Al₂O₃/SiC mixed nanofluid MQL with multi-angle two-dimensional ultrasonic vibration grinding was studied experimentally.As follows was idiographic research:1.The lubrication mechanism related to MQL grinding of Al₂O₃/SiC mixed nanofluid was studied,and the evaluation parameters of lubrication performance were investigated.The lubrication performance was characterized by grinding force,grinding force ratio,specific grinding energy,workpiece removal parameters,surface roughness,and micro-morphology of workpiece surface and debris surface.2.The effect of different concentrations of Al₂O₃/SiC mixed nanofluid on the lubricating performance of grinding wheel/workpiece interface was studied,and the lubricating properties of Al₂O₃ nanofluid and pure SiC nanofluid were compared.The superiority of micro lubrication of mixed nano fluid was analyzed,and the optimum concentration ratio of Al₂O₃/SiC was obtained.3.Nanofluid was prepared by mixing Al₂O₃ and SiC nanoparticles with different particle sizes.The experiments of micro-lubricating grinding of high-hard Ni-base alloy with nano-particle jet were carried out.By analyzing the grinding performance parameters:specific grinding force,workpiece removal parameters,surface roughness?Ra value,RSm value and profile support length ratio?,debris morphology,contact angle and cross-correlation analysis of the surface profile curve of the workpiece.The effect of different“physical synergism”and“coating effect”on lubricating performance of Al₂O₃/SiC mixed nano-fluid with different particle size was investigated.4.The jet parameters of MQL with Al2O3/SiC mixed nanofluid were optimized by orthogonal experiment.The experimental results were verified on the basis of several relatively optimized jet parameters,and the power spectral density analysis of the micro-morphology of the workpiece surface was carried out.The surface morphology and debris morphology of the workpiece were analyzed,and the optimal jet parameters were obtained.5.The combined resonance of two-dimensional ultrasonic vibration system is studied by mechanical impedance.The dynamic response of the vibration system excited by ultrasonic frequency signal is analyzed.The resonant frequencies of tangential ultrasonic oscillator and axial ultrasonic oscillator are obtained as 19960Hz and 19930Hz,respectively.According to the theory of ultrasonic vibration,the relative motion characteristics of grinding wheel abrasive particles and workpiece are analyzed from the angle of kinematics in multi-angle two-dimensional ultrasonic vibration assisted grinding.For the first time,a mathematical model of the relative motion of abrasive particles and workpieces for grinding wheel with multi-angle two-dimensional ultrasonic vibration assisted grinding is established,and the elliptical geometry of the grinding wheel with different angles is obtained by Matlab simulation.The characteristics of the motion trajectory of lapping and the relative motion trajectory of abrasive particle and workpiece in a single cycle.According to the contact arc length model of grinding wheel abrasive cutting,the time required for grinding particles from cutting into the workpiece to cutting out the workpiece is calculated,and the vibration period of ultrasonic vibration is combined.The vibration times of ultrasonic vibration system in the process from cutting into the workpiece to cutting out the workpiece are calculated and the characteristics of the two-dimension ultrasonic vibration grinding in one cutting and many times of optical grinding are verified.6.The equipment design of multi-angle two-dimensional ultrasonic vibration grinding system was carried out,then the construction was carried out.Moreover,according to the mathematical model of relative motion of grinding wheel and workpiece and Matlab simulation results,the experimental study is carried out on the basis of multi-angle two-dimensional ultrasonic vibration assisted grinding,the surface generation mechanism of multi-angle two-dimensional ultrasonic vibration assisted micro lubricating grinding of Al₂O₃/SiC mixed nano-fluid was studied experimentally.The surface quality and micro-morphology of workpiece were compared between one-dimensional ultrasonic vibration and two-dimensional ultrasonic vibration grinding.At the same time,adjusting the axial ultrasonic oscillator to change the vibration direction of two-dimensional ultrasonic vibration,the optimal vibration angle is studied.