| Surfaces with micro-groove structures make devices exhibit more excellent characteristics in heat transfer,hydrodynamic,chemical reaction and frictional properties,and have great potential for industrial application.In order to solve the problems in micro-groove arrays machining on difficult-to-cut metal surface,a method of pulse electrochemical machining in discrete fields and domains is presented,which can machine these structures with high efficiency,high precision,good surface quality and high processing stability.The research contents of this dissertation are divided into the following parts:1.A new method of pulse electrochemical machining of micro-groove arrays in discrete fields and domains was proposed.In the method,the entire machining zone is divided into multiple fields with a nonconducting masking template,each field corresponds to an independent processing area and the processing area does not affect each other,so a better processing environment can be created for electrochemical machining.To meet the requirements of different processing depth of micro-groove,two processes using movable fence-like mask electrochemical machining and multi-wire electrochemical machining in discrete fields and domains were designed,and special fixtures were designed according to the specific conditions of these two methods.2.COMSOL Multiphysics software was used to simulate the electrochemical machining of micro groove arrays in discrete fields and domains,and the feasibility of presented method was verified.From the simulation results of electrolyte flow,the flow rate of electrolyte in the machining zone can be increased when the entire machining zone is divided into several independent fields,and the difference of the velocities of electrolyte between each field is small.The masking template with the array channels not only helps to realize the field dispersion,but also has the effect of shielding the non-processing area on workpiece surface,so that the non-processing area is not affected by electrolyte.3.Verification experiment of micro groove arrays machining process with movable fence-like masking template using electrochemical machining in discrete fields anddomains was carried out.Using this method,9 micro-grooves with 538.76?m width,25.78?m depth and overcut 19.38?m were obtained within 1 minute.Then,single factor experiments and orthogonal experiments were designed and carried out to optimize the processing parameters.4.Experiments of single groove cutting process with multi-wire electrochemical machining in discrete fields and domains were performed.The comparison experiments with and without masking template were conducted.It was found that the masking template can successfully constrain the processing geometry and thus improve the surface quality of groove.Micro groove with 981?m width and 1058?m depth was successfully fabricated on stainless steel surface with this process,in which a masking template with notch width 1mm and wire cathode with diameter of 0.3mm were utilized.Then,single factor experiments and orthogonal experiments were designed and carried out to optimize the processing parameters.5.Multi-wires electrochemical micromachining of micro-groove arrays in discrete fields and domains were carried out.From the experimental results,the feed rate of wire electrodes 0.2 mm/min could not be achieved without the masking template,while with the masking template,the machining becomes possible in this feed rate because of the discretization of electrolyte flow field in machining zone.To explore the influence of template material on micro-groove machining,the elastic template was also used,which proves to help the processing more stable and eliminate the stray corrosion zone.This is because that during the whole processing period,the elastic template can be tightly pressed onto the workpiece surface,thus completely prevent the electrolyte from entering the non-processing zone,therefore corrosive pitting is eliminated. |
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