Investigation On The Lubricating Performance And Mechanism Of Electrostatic Atomization Cutting Using Micro Oil-based Nanofluids

Minimal quantity lubrication(MQL) has become a common concern of cooling and lubrication technology due to the fact that it reduces the use of cutting fluids greatly and shows good cutting performance. However, its cooling and lubricating performance can not meet the high demands of high efficiency machining. Moreover it can lead to high oil mist concentration in cutting environment. In order to improve cooling/lubrication performance and ambient air quality, therefore the cutting/lubricating performance and mechanism of oil-based nanofluids in electrostatic atomization cutting were investigated in this paper. The major research works are as follows:(1) Dispersion and thermal physical properties of nanofluids used in cuttingThe oil-based nanofluids were prepared by two-step method. The nanoparticles used in this research are graphite, multi-walled carbon nanotubes and diamond, and meanwhile LB2000 vegetable-based oil was chosen as base fluids. The influence of volume fraction,particle size, particle type and vibration time on particle size distribution, viscosity, surface tension and thermal conductivity was investigated. The influence rules of above factors on dispersion and thermal physical properties of nanofluids were found. Further, the theoretical basis for selecting nanofluids used in cutting was provided.(2) Tribological properties of oil-based nanofluidsA pin-on-disk friction and wear tester was used to investigate the tribological properties of oil-based nanofluids. It was found that the friction-reducing and antiwear properties of base oil could be significantly improved by the addition of graphite nanoparticles and carbon nanotubes. Combined with tribological model and surface morphology as well as energy spectrum analysis of titanium alloy disk, the lubrication mechanisms of graphite nanoparticles and carbon nanotubes as vegetable based oil additive were revealed.(3) Simulation of electrostatic field based on electrostatic atomization cuttingBased on the concept of electrostatic atomization cutting, a finite element model of electrostatic field for electrostatic atomization cutting was developed using a commercial software Ansoft Maxwell. The influence of nozzle angle, electrode distance, electrode voltage and nozzle structure on electrostatic field intensity was analyzed. The variation of electrostatic field intensity with above factors, optimal nozzle angle and structure wereobtained. Thus, the findings provided a theoretical basis for electrostatic atomization cutting experiments.(4) Electrostatic atomization cutting experiments of oil-based nanofluidsElectrostatic atomization cutting system of oil-based nanofluids was constructed.Milling experiments of titanium alloys and the detection of oil mist concentration in cutting environment were conducted. The influence of cooling and lubrication conditions on tool wear and oil mist concentration was analyzed. The experimental results suggested that compared with minimal quantity lubrication, electrostatic atomization cutting of oil-based nanofluids not only effectively reduced the tool wear but also remarkably improved the ambient air quality.