阴极调速法测定电解加工ηω-i曲线特性的试验研究及其应用

Study on Characteristics of ηω-i Curve in ECM by Cathode Speed Control Method

镍基高温合金GH4169是航空发动机叶片的常用材料。为了精确获取GH4169的ηω-i曲线特性,采用调节阴极进给速度的新方法,实时控制加工间隙,使加工过程迅速过渡到平衡状态。利用阴极调速法开展了电解加工试验,经过计算得出ηω-i曲线。结果表明:当电流密度i小于6A/cm2时,ηω值趋向于0;当i大于50A/cm2时,ηω保持在1.28mm3/(A.min)不变。针对某航空发动机叶片,基于阴极调速法和恒速法测定的ηω-i曲线特性,分别设计了工具阴极,并开展了对比工艺试验研究。研究表明:根据阴极调速法测得ηω-i曲线特性设计的阴极,加工出叶片的复制精度明显提高,叶片精度整体提高0.03mm,证明该方法测定ηω-i曲线特性更加准确。

Ni-based superalloy GH4169 is a material frequently used for aeroengine blades. To obtain the characteristics of the ηω-i curve of GH4169 precisely,a new method called the cathode speed control method is adopted to control the machining gap so that the machining process can reach an equilibrium state quickly. Electrochemical machining （ECM） experiments are conducted by means of this method and the ηω-i curve is drawn after a series of calculation. The curve shows that when current density i is below 6 A/cm2,the ηω value approaches 0; and when i is above 50 A/cm2,the ηω keeps constant at the point of 1.28 mm3/（A·min）. In the final part of this article,two cathodes are designed respectively in light of a certain aeroengine blade and their different ηω-i curves drawn respectively by the speed control method and the unchanged speed method. Then,contrastive experiments between them are carried out. The results show that the cathode designed according to the ηω-i curve by the speed control method achieves better duplication accuracy,and the overall blade accuracy is increased by 0.03 mm. Therefore,the characteristics of the ηω-i curve obtained by this new method are more satisfactory.