Reasearch On Surface Texturing And Parameters Optimization Of Radical Ultrasonic Rolling Electrochemical Micromachining

The non-smooth surface texturing at micrometer scale on the metal to replace the traditional surface strengthening treatment process can not only reduce costs,but also improve the performance of the products,such as reducing friction and wear,reducing resistance,improving bearing capacity,and avoiding surface adhesion and seizure.However,this kind of structure is small in size,various in shape and mostly in group structure.What's more,the materials used for machining are usually metals.Sometimes,some special materials(titanium alloy,nickel,super alloys and stainless steel,etc.)are used to satisfy the requirements.This has brought certain difficulties to machine,and has become a bottleneck restricting high-tech products,which needs to be resolved urgently.In order to realize the high efficiency and precision machining of surface texturing at micrometer scale on the metal,this paper proposes a new machining method based on electrochemical micromachining and ultrasonic energy field—radial ultrasonic rolling electrochemical micromachining.The micro-jet will be formed in the inter-electrode gap when the ultrasonic vibration is applied.This changes the flow state of the flow field,promotes the electrolyte renewal in the processing zone of the gap and enhances electric field distribution in the gap.The surface quality,material removal rate and roughness of surface texturing could be improved.The main research contents of the paper are as follows:(1)The motion law and gap characteristic of radial ultrasonic rolling electrochemical micromachining are expounded.By the research of the elliptical vibration mode of the cathode and the impact of the gap micro-jet on the both bottom and side walls,radial ultrasound is confirmed its superiority of improving the surface quality,and the conclusion is further confirmed by SEM photos of forming dimple's wall.(2)The experiment of electrochemical micromachining with or without radial ultrasonic energy field is carried out to study the influence of different electrical parameters on micro dimples array's accuracy,forming consistency and material removal rate.The results show that after applying ultrasonic vibration,the depth of micro dimple is increased by 45%-50%,and the cross-sectional area is increased by40%-45%.What's more,with the voltage is increased from 9 V to 12 V,the roughness of micro dimple bottom generated without radial ultrasonic fieldis is decreased from 0.310?m to0.616?m while the roughness of micro dimple bottom generated by radial ultrasonic rolling electrochemical micromachining is decreased from 0.233?m to 0.177?m.(3)The gap pressure measurement system and the current measurement system are separately established to study the influence of the gap pressure on the machining performance and the effect of the current on the passive film.Gap pressure measurement results show that in one period of time,the gap pressure change curve of electrochemical micromachining is close to a straight line,and the peak pressure is increased from 0.05 MPa to 0.08 MPa with the voltage increased from 9 V to 12 V;the gap pressure change curve of radial ultrasonic rolling electrochemical micromachining is approximately sinusoidal,and the peak pressure is increased from0.76 MPa to 1.01 MPa with the voltage increased from 9 V to 12 V.Current measurement results show that the ultrasonic vibration has a certain effect on the breakdown time of the passive film.When the current density is small,that is,the processing gap is large,the breakdown time of the passive film decreases rapidly with the increase of the current density,and when the current density continues to increase to a certain extent,the breakdown time of the passive film will eventually tend to a stable value 0.109 s.(4)Based on processing parameters,the response surface methodology is used to systematically study the influence of different parameters on target parameters such as roughness and material removal rate of micro dimples,and then establish a mathematical model of the target parameters to provide more excellent processing plans for machining typical surface texturing.The results show that within the experimental parameters set in the paper,the optimal parameters at the maximum removal rate is the voltage 14.08 V,the rotation speed 0.15°/s,the pulse frequency5.70 Khz,the machining gap 59.54?m,and the corresponding removal rate is 0.0596mm~2;the optimal parameters are when the roughness is minimum.The optimal parameters at the minimum roughness is the voltage 13.40 V,the rotation speed0.15°/s,the pulse frequency 5.35 Khz,the machining gap 57.76?m,and the corresponding roughness is 49.895 nm.At the same time,experimental verification was performed based on the optimized parameter combination.The error between the removal rate simulation and the experiment was 0.8%,and the error between the roughness simulation and the experiment was 2.4%,which indicated that the fitting result is reliable.