Spray Flow Field Characteristics Of Electrostatic Minimal Quantity Lubrication And Its Influence On Lubrication Performance

In the metal machining Process,cutting fluid is usually heavily used to decrease the friction between tool and workpiece,lower cutting temperature and reduce the workpiece roughness.At all stage of manufacture,using,waste treatment and disposal,cutting fluid brings excessive resource consumption and environmental pollution.With the growing environmental awareness,taking the minimal quantity lubrication representative of Green Manufacturing is imperative.On the basis of the minimal quantity lubrication(MQL)and the electrostatic spray(ES),the electrostatic minimal quantity lubrication(EMQL)technology has been developed.It has many characteristics,such as smaller and more uniform droplet size,smaller surface tension and contact angle,stronger adsorption,etc.The advantages of these characteristics are used to improve lubricating-cooling performance.In this paper,for the spray flow field characteristics of the electrostatic minimal quantity lubrication,the main research is as follows:Firstly,the FLUENT software is introduced to simulate the atomizing area of downstream of the nozzle.Analyze the distribution of droplet velocity and diameter under different air supply pressure,oil flow rate and electrostatic voltage.The results indicate that with the increase of air supply pressure,the droplet velocity increases and the droplet diameter decreases;With the increase of oil flow rate,the droplet velocity decreases and the droplet diameter increases within a certain range;With the increase of electrostatic voltage,the droplet velocity increases and the droplet diameter decreases.Secondly,the droplet velocity measuring device was set up,and the PIV(Particle Image Velocimetry)technology was used to measure and analyze the spray flow field on the traditional minimal quantity lubrication and the electrostatic minimal quantity lubrication.The results indicate that in contrast to the minimal quantity lubrication,both the droplet velocity and the spray cone angle increased because of the effects of electrostatic field on electrostatic minimal quantity lubrication.The droplets collecting device was set up,and the Matlab image recognition and detection technology was used to collect and identify droplets.The results indicate that with the voltage increases,the Sauter mean diameter(SMD)of droplets decreases on the electrostatic minimal quantity lubrication,the distribution of the droplet diameter become more uniform and the spray quality is improved dramatically.Thirdly,it shows that the simulation model can predict the charged two-phase flow in a certain extent by comparing the simulation results with the experimental results of the distribution of the droplet velocity and diameter.Lastly,the influence of the spray flow field characteristic parameters on the friction and wear properties was studied and analyzed by using four-ball friction tests on the electrostatic minimal quantity lubrication.The results indicate that in contrast to the minimal quantity lubrication,the electrostatic minimal quantity lubrication significantly improves the lubrication of the friction field and reduces the friction coefficient and wear rate;The spray flow field characteristics have an influence on the lubrication of the friction field;These characteristics include physical and chemical properties of charged droplets,the distribution of droplet velocity and diameter,etc.There exists a condition of optimal charge voltage,oil flow rate,air pressure and spray distance,which makes the effect the most significant on the electrostatic minimal quantity lubrication.