脉冲气体辅助掩模电解加工技术

Pulse gas-assisted through-mask electrochemical machining technology

表面织构被广泛应用于航空发动机关键零部件中,以提高其散热及润滑效果。掩模电解加工是一种高效加工表面织构的工艺方法,但加工中存在加工产物难以排出、电解液流速不均匀以及加工一致性难以保证等问题。为此,提出一种脉冲气体辅助掩模电解加工的新方法,该方法利用脉冲气体的瞬间冲击力对加工区域的电解产物进行冲刷,以促进加工区域电解液的更新。为了研究脉冲气体辅助掩膜电解加工工艺规律,基于COMSOL Multiphysics仿真软件建立了单喷嘴固定条件下加工区域气液两相流与电场耦合的多物理场理论模型。仿真结果显示,当喷气速度为100m/s时,掩模孔底部流体流动速度最大可达到3.5mm/s。加工后掩模板表面能够清晰看到产物的排出痕迹。此外,还探究了不同工艺参数对加工一致性与加工效率的影响规律。实验结果表明,喷嘴固定不动时加工一致性随脉冲气体喷射速度的减弱以及喷气脉冲间歇时间的增加而提高,而加工效率却会降低,实验中得到微坑深度标准差最小达到0.75μm,平均深度最大达到15.2μm。最后,分别对比了实验中有无脉冲气体辅助的加工结果以及模拟和实验的成形规律,并在喷嘴移动条件下加工出深度标准差与平均深度分别为1.06μm与10.7μm的阵列凹坑。结合理论分析与实验研究结果,证明该方法对加工区域流体具有强烈扰动作用,能够同时提高加工效率与加工一致性。

Surface texture are widely used in key components of aero engines to help improve their heat dissipation and lubrication.Through-mask electrochemical machining is a highly efficient method for processing surface texture,despite some problems in processing such as uneven flow velocity of electrolyte,difficult to discharge the processed products and ensure the consistency of the surface texture,etc.Therefore,a new method of pulsed gas-assisted through-mask electrochemical machining was proposed,which could use the instantaneous impact force of the pulse gas to wash the electrolysis products in the machining area,thereby promoting the renewal of the electrolyte.In order to study the process law of pulsed gas-assisted through-mask electrochemical machining,under the fixed condition of a single nozzle,a multi-physics model of gas-liquid two-phase flow coupled with electric field was established based on COMSOL Multiphysics simulation software.Through theoretical analysis and experimental study,it was proved that this method has a strong disturbance effect on the fluid in the processing area.The simulation results show that the maximum fluid flow velocity at the bottom of the mask hole was about 3.5 mm/s at a jet velocity of 100 m/s.Traces of product dis-charge can be clearly observed on the surface of the processed mask.In addition,the effects of different process parameters on processing consistency and efficiency were studied.The experimental results show that with the increase of the pulse interval of the jet and the decrease of the gas injection speed,the processing consistency would increase and the processing efficiency would be less.In the experiment,the standard deviation of micro-pit depth could reach a mini-mum of 0.75μm and the average depth could reach a maximum of 15.2μm.Finally,the machining results with or without pulsed gas assist and the forming laws of simulation and experiment with pulsed gas assist were compared.Then,the array pits with the standard deviation of depth and the average depth of 1.06μm and 10.7μm were processed in the condition of nozzle scanning.Combining theoretical analysis and experimental research results,it was proved that this method had a strong disturbing effect on the fluid in the processing area,and could improve processing efficiency and consistency.