电化学对微小孔毛刺去除的仿真及试验

Simulation and Experimental Study on Electrochemical Deburring of Microhole

钻削微小通孔产生的孔口毛刺严重影响了其表面质量,且微小孔因直径小导致其入口和出口毛刺去除困难,为此提出基于电化学的微小通孔双面毛刺的同步去除方法。以0.35 mm厚的304不锈钢板的钻孔毛刺为研究对象,建立电化学毛刺去除仿真模型,分析电流密度与微小孔不同区域材料去除速率间的对应关系,研究电极位置及工艺参数对毛刺去除效果的影响,并开展相关试验研究。结果表明,孔口表面电流密度大小表征了材料去除能力的强弱,毛刺尖端电流密度大,孔内壁电流密度小且分布均匀;电极位置对出口毛刺去除速率影响大,伸出型电极毛刺去除效果最好;随加工电压、电解质浓度及电极直径增大,毛刺去除效率增高,但扩孔率增大,且电极直径越大入口倒角越明显;试验基于伸出型电极位置,采用4 V加工电压、12%NaNO_(3)电解质、0.2 mm电极半径,实现了孔口毛刺的精准去除,加工后的倒角宽度为38μm,扩孔率仅1.99%,验证了仿真的准确性。研究结果可为微小通孔双面毛刺的高效、精准去除奠定研究基础。

Microholes are widely used in aero-engines,fuel nozzles,and in the biomedical,micro-electromechanical,and other fields.Microholes are often processed by microdrilling.However,orifice burrs are produced during the drilling process,which significantly affect the surface quality of microholes.The small diameter of through-microholes also makes it difficult to remove their entrance and outlet burrs.Therefore,an electrochemistry-based synchronous removal method for the double-sided burrs of through-microholes is proposed.An electrochemical burr removal simulation model was established based on the drilling burr of a 304 stainless steel plate with a thickness of 0.35 mm as the research object,and the correspondence between the current density and material removal rate in different areas of the microholes was analyzed.Parameters such as the chamfer width and reaming rate were used as evaluation indicators.The influence of parameters such as the electrode position,processing voltage,electrolyte concentration,electrode radius,and process on the burr removal effect was studied,and related experimental studies were carried out.1)The surface current density of the orifice determines the strength of the electrochemical removal ability of burr materials.The current density of the burr tip is large and that of the outlet is greater than that of the entrance.The current density of the front of the burr is greater than that of its back.The current density of the inner wall of the microholes is low and evenly distributed,while that of the nonmachined area of the outer wall of the orifice is almost zero.As the height of the burr decreased,the current density spikes in the areas at both ends of the hole wall gradually moved toward the middle area.2)The electrode position significantly influences on the outlet burr removal rate but has little effect on the inlet burr removal rate.The extended-type position of the electrode helps improve the efficiency of outlet burr removal as well as reduces the reaming rate and entrance chamfer of the microholes.It also has the best burr removal effect.The aligned-type electrode position has the second-best removal effect,while the inline-type electrode position has the worst.3)The burr removal efficiency and reaming rate increased as the processing voltage,electrolyte concentration,and electrode diameter increased.The chamfer width was mainly affected by the electrode diameter.The larger the diameter,the more obvious the entrance chamfer.For through-microholes with a radius of 0.4 mm,the best burr removal effect was achieved using a 4 V processing voltage,12%NaNO_(3)electrolyte,and an electrode radius of 0.2 mm.The chamfer width after deburr removal was 38μm and the reaming rate was only 1.99%,which is in good agreement with the simulation results.The bubble layer generated by electrolysis hindered the removal of material from the inner wall of the microholes,thereby reducing the reaming rate.The proposed electrochemical synchronous removal method of through-microhole double-sided burrs improved the efficiency and accuracy double-sided burr removal,and the morphological quality of orifices.To improve the burr removal effect,while taking into account the removal efficiency,the extended-type electrode position should be selected;the processing gap should be maximized;and the processing voltage and electrolyte concentration should be reduced.The established electrochemical model improved the simulation of the burr removal process,but failed to consider the influence of electrolytic bubbles.This resulted in deviations between the simulation and experimental results.