Research On Process Characteristics Of Oil-in-Water Working Fluid Based On Density Balance

Electrical discharge machining(EDM)is an important machining method in special machining.It is widely used in many industries,such as mould manufacturing,electronics,aerospace,precision machinery and so on.In order to promote the green development of EDM,This dissertation presents an oil-in-water green working fluid based on density equilibrium,which can combine the advantages of oil-based working fluid and waterbased working fluid.The machinability and material removal mechanism of EDM are studied and some theoretical results are obtained.By means of theoretical analysis,simulation analysis and experimental analysis,the working liquid stability,machining flow field and discharge mechanism of water-in-oil EDM are systematically studied in this dissertation.The force of kerosene droplets containing powder in water-in-oil working fluid was studied.The movement,coalescence and splitting of kerosene droplets in deionized water were analyzed.The force model of kerosene droplets in deionized water was established.The coalescence and fragmentation of the droplets in the electric field were simulated and analyzed,and the stability of the droplet motion under the action of the electric field was studied.Based on the simulation and analysis of the gap flow field of the water-in-oil type EDM,the mathematical model and the simulation model of the gap flow field in the EDM of the water-in-oil type working fluid are established by using the method of external flushing fluid.The effects of inlet velocity of working fluid,machining depth and electrode size on clearance flow field and etching products in the flow field were studied.The effects of kerosene droplets with powder on dielectric constant,discharge gap between electrodes and discharge process were studied.It is found that the electric field between the electrodes is distorted and the breakdown voltage can be reduced by the simulation.The thermal process of EDM was simulated by simulation,and the material removal mechanism was studied.Through a large number of EDM experiments,the processing conditions of water-inoil composite working fluid,kerosene working fluid and deionized water working fluid under different open circuit voltage,peak current,pulse width and pulse interval are studied and compared.The influence of each electrical parameter on the machining effect of the workpiece is studied.It is found that the processing efficiency of kerosene working fluid is higher than that of water-in-oil working fluid in comparison with that of the working fluid of water-in-oil type.