电火花成形电极包络修整叶片边缘工艺的探究

Research on EDM Electrode Envelope Trimming Blade Edge Process

航空发动机叶片进排气边缘的精度直接影响着飞机的气动性能。为解决电解加工叶片存在的叶缘尺寸误差问题,提出了采用成形电极曲面,以“线-线”接触方式,电火花包络加工的方法对叶片边缘进行修整,即通过共轭曲面的基本原理设计出与理论叶缘曲面互相啮合的电极曲面,当电极与叶片按照刀位轨迹进行共轭运动时,电极曲面与叶缘曲面在每一个刀位点处始终保持有且仅有一条线接触,利用该特征曲线(刀刃线)对叶缘毛胚余量进行蚀除,再利用自研的六轴电火花机床对叶片毛胚进行了边缘修整实验。实验结果表明:修整后的叶片叶缘整体尺寸误差范围为-16.4~88.5μm、电极相对体积损耗率为0.87;通过对电极曲面不同部位的损耗情况进行分析,确定了电极曲面损耗严重区域的位置以及相应的材料去除量与电极损耗的关系,为后续的电极补偿提供了依据。

The accuracy of the leading and trailing edges of aero-engine blades seriously affects the aerodynamic performance of the aircraft.To correct the edge size and shape errors by electrical chemical machining,proposes a method of trimming the blade edges by electrical discharge machining(EDM)“line-line”contact using a curved surface electrode.Based on the basic principle of conjugate surface,the electrode surface is designed to match theoretical blade edge surface.When the electrode moves along the tool path of conjugation movement,the electrode surface and the blade edge surface always maintain a line contact at each tool position,and the material of blade edge is removed.The blade edge trimming experiment is carried out on the self-developed six-axis EDM machine.The experimental results show that the overall size error of the trimmed leaf edge is in the range of-16.4~88.5μm.The relative volume wear rate of electrode is 0.87.The wear location on different parts of electrode surface and the corresponding relationship between the material removal volume and the electrode wear volume are analyzed.This provides a basis for the subsequent electrode compensation.