Technical Research On Array Dimples Air-shielded Electrochemical Micromachining

Surface textures can effectively improve the friction,bearing capacity,and lubrication performances of various mechanical components.Hence,it has been widely used in agricultural machinery,aerospace,mechanical engineering and other fields.Hydraulic jump is presented,and the electric current is distributed around machining area,which deteriorates the localization and surface roughness in EMM because the high speed and the high pressure electrolyte are employed.In view of the electrochemical processing technology and air-film protection principle,a new processing method,AS-EMM was proposed to improve the surface quality and the machining accuracy in this study.A continuous stream of an electrolyte surrounded by a high-pressure air jet is blasted onto the workpiece.The pure electrolyte area is shrink and gas-liquid mixing flow field is extended,so the characteristics of the interelectrode fluid and the electric field are improved.The main contents of the paper is as follows:1.Based on the theory of fluid dynamics,multiphase flow,combined with the finite element analysis method,the flow and distribution of the electrolyte flow field between nozzle and a workpiece were simulated by the ANSYS FLUENT.The gas-liquid volume fraction and flow field velocity of the workpiece surface were captured,which are able to describe the electrolyte flow state and the change rule.Furthermore,the distance between nozzle and a workpiece surface,the distance between gas and liquid,the distance among electrode and such design parameters were optimized.2.Direct current power was employed to conduct confirmatory experiments by optimal parameters of single electrode nozzle.Dimensions and surface accuracy were measured by SEM(scanning electron microscope)and optical profiler.In addition,the taper and standard deviation were calculated.Compared with traditional electrochemical micromachining(EMM),the average diameter of dimples is reduced by 40%,the deviation of the diameter is reduced by 67.7%,taper is increased by 42%.In addition,the standard deviation were calculated.The results suggest that localization and stability by air-shielding electrolyte jet machining are improved when using appropriate machining parameters.3.Micro-dimple arrays and grooves were created on a stainless steel surface with the consideration of the effects of machining parameters,including the air velocity,the electrolyte velocity,applied voltage,the feeding speed and pluse frequency.The results show that the better quality array micro-dimples with the higher taper are able to be achieved when the pulse period,pulse period,electrolyte velocity,air velocity,voltage,and feeding speed are 12?s,6-7?s,5m/s,100m/s,12 V and 70?m/min respectively.4.Based on the theory of Support Vector Machines(SVM),the Matlab was employed to find the optimized parameters with the consideration of the machining efficiency,localization,and dimension consistency of micro-dimples.In AS-EMM,the dispersive corrosion,localization and dimension consistency can be improved.The results are able to be the valuable references in the array electrochemical machining field and related engineering.