| As a typical micro scale structure,micro grooves with a certain size and shape are widely used in micro sensors,micro reactors,micro fluidic devices and micro fuel cells.How to realize the precision,high efficiency and low cost manufacturing of micro grooves with complex shapes has become the focus of research.At present,the machining methods of micro groove mainly include mechanical micromachining,laser beam micromachining,electrical discharge micromachining and electrochemical micromachining.Electrochemical machining has obvious advantages in metal microstructure processing due to its features of stress-free contact,no cutting heat,no electrode tool wear,and ion level material removal.Aiming at the problems such as complex mask making process,difficult to eliminate electrolytic products,and poor consistency of groove size in traditional electrochemical machining,this paper proposed a novel approach of masked jet electrochemical machining for micro groove structure.A flexible insulated mask with micro through holes was covered on the head surface of a metallic nozzle.During machining,the mask on the modified nozzle was contacted with the workpiece,and the jetting electrolyte in the nozzle was divided into different machining regions by the micro-through-holes in the mask,then,the micro grooves could be generated by moving the workpiece with an effective voltage applied between the nozzle and workpiece.By controlling the relative motion between nozzle and workpiece,complex curved shape or array micro grooves can be processed from dot to line scanning.The main contents of this paper are as follows:(1)A masked jet electrochemical machining method was proposed,and an experimental device for micro groove machining was built.The software development of motion control and data acquisition based on the Lab VIEW platform was carried out to meet the requirements of the processing experiment.(2)In this paper,the forming process of micro grooves in masked jet electrochemical machining is theoretically analyzed by ANSYS electric field simulation.The simulation of single-point micro dimple forming process and the simulation of point-line micro groove forming process were completed respectively.The process of forming transition arcs at both starting and ending points of micro groove was analyzed by calculating the current density change,and the arc profiles of the theoretical calculation and the actual machining of micro groove at both starting and ending points were compared.The influence of pulse voltage,mask size and scanning speed on the simulation results of micro groove was studied.(3)On the basis of the simulation results,the experimental verification was carried out.The relationship between the key parameters,such as pulse frequency,pulse duty cycle,scanning speed and scanning times,and the machining localization,material removal rate and current efficiency of the micro grooves was studied.Finally with the optimized parameters(pulse voltage 30 V,pulse frequency 1000 Hz,pulse duty cycle20%,scanning speed 20 μm/s),serpentine,straight line,cross shape micro grooves and array microslit structure with the width of 90 μm,the depth of 20 μm were successfully generated,verified the feasibility of the masked jet electrochemical machining method.(4)In order to improve the localization of processed micro groove,the conductive mask was used to replace the insulation mask for the simulation and experimental study.The simulation results showed that using conductive mask could change the electric field distribution in the micro groove processing area,reduce the electric field identity at the edge of the mask hole,and reduce the undercutting of the profile compared to that generated with insulated mask.In the experiment,the etch factor(EF)increased from1.47 to 6.11 using conductive mask,which showed a low undercutting and high machining localization. |
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