Research On Electrochemical Machining Of Microgrooves In Flexible Metal Sheet

Multi-microgrooves structure are typical structures of microchannel heat exchangers and fuel cell bipolar plate,which were mainly used to cool high heat flux devices.Microgrooves' size is between 10?m~500?m,and requires high precision.The workpiece is easy to deform during the machining process,the material of workpiece is usually hard to machine.Thus it's difficult to machine multimicrogrooves.Electrochemical micro-machining(ECMM)is based on the principle of electrochemical anodic dissolution,and the material is removed as ions.Thus,ECMM has great advantages in micro machining.In this paper,the ECMM of multi-microgrooves in flexible metal sheet is studied.Firstly,high-precision array microelectrodes of tungsten is prepared and then multi-microgrooves are processed.The main works of this paper are listed as follows:1.ECMM of tungsten using a rotary helical electrode.The polarization curves of tungsten in different types of solutions were determined,and the electrochemical characteristics of tungsten were analyzed.At last,potassium hydroxide was selected as the electrolyte.The optimal process conditions are determined experimentally: a KOH electrolyte concentration of 0.4 mol/L,a 10% pulse duty ratio,and a 500 kHz in pulse frequency.2.Precision machining of tungsten arrayed microelectrode.An experimental system of tungsten arrayed microelectrode machining was set up.Under the optimal conditions,the side gaps at different applied voltage(6.5V to 10V)and feed rate(0.1?m/s to 0.5?m/s)were obtained in experiments.A quantitative relationship between the side gap and the applied voltage and electrode feed rate was obtained by multivariate regression analysis.Besides,a contour map was drawn to aid in selecting the appropriate process parameters to achieve specific slit width.At last,tungsten array microelectrodes with same and variable cross-section were fabricated.3.ECMM of microgrooves in flexible metal sheet.Firstly,a flexible metal sheet was fixed in a cylindrical fixture.After the tungsten microelectrode radial fed for a depth,the cylindrical fixture start to rotate,and the continuous machining of multi-microgrooves is processed.An experimental system of ECMM of multi-microgrooves in flexible metal sheet was set up.The optimal process conditions are determined experimentally: 15% pulse duty ratio,and 5?s pulse period.The numerical analysis of the ECMM of microgrooves using electrodes of different thickness was carried out.The current density distribution at microgrooves' different parts were presented.Under the optimal conditions,five multimicrogrooves with 166.65?m in width and 24.34?m in depth were fabricated.