Breakthrough detection in electrochemical discharge drilling to enhance machining stability
Breakthrough detection in electrochemical discharge drilling to enhance machining stability
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DOI：
10.1016/j.cja.2022.09.023
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发表时间：
2022-09
影响因子：
5.7
通讯作者：
Tianyu Geng;Zhengyang Xu;Chenxiang Zhang;Jin Ning
中科院分区：
文献类型：
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作者：
Tianyu Geng;Zhengyang Xu;Chenxiang Zhang;Jin Ning
气膜冷却孔在航空发动机涡轮机叶片中应用广泛。这些叶片具有大量复杂角度的孔，需要高水平的表面完整性。电化学放电钻进是将放电钻进的高效率和电化学钻进的高质量结合起来的一种新型钻进技术。然而，由于存在各种能量用于材料去除，准确和及时地检测突破充满了困难。预设的安装距离不足会导致微小的出射孔径，影响结构的形状。此外，电极在大的过馈距离处易于弯曲，从而导致二次放电，破坏侧壁表面完整性。本文比较分析了EDD和ECDD处理波形的特点。提出了一种基于平均电压方差信号（VSAV）的穿透检测方法，以提高加工稳定性，实现无重铸层加工。该方法通过计算平均值的方差来提取波动变换。在信号检测之后，量化过度进给距离。实验用于验证在所有测试中具有100%准确度的突破检测。获得了孔角为0 °、30 °和60 °时的最佳超喂距离，实现了重铸层的稳定去除。最后，以典型的双壁结构工件和镍基单晶叶片为例，验证了该方法的有效性。
Film cooling holes are widely used in aero-engine turbine blades. These blades feature large numbers of holes with complex angles and require a high level of surface integrity. Electrochemical discharge drilling (ECDD) combines the high efficiency of electrical discharge drilling (EDD) with high quality of electrochemical drilling (ECD). However, due to the existence of a variety of energy for material removal, accurate and timely detection of breakthroughs is fraught with difficulties. An insufficient preset setting distance results in a tiny exit aperture, influencing the structure’s shape. In addition, the electrode is prone to bending at a large overfeeding distance, causing secondary discharge damaging sidewall surface integrity. This paper compares and analyzes the characteristics of processing waveforms using EDD and ECDD. A novel breakthrough detection method is proposed based on the variance signal of average voltage (VSAV) to increase machining stability and achieve fabrication without a recast layer. This method extracts the fluctuation transformation by calculating the variance of the average. Following signal detection, the overfeeding distance is quantified. An experiment is used to validate the breakthrough detection with 100% accuracy in all tests. The optimum overfeeding distances for hole angles of 0 °, 30 °, and 60 ° are obtained, and the stable removal of the recast layer is realized. Finally, the effectiveness of the method is verified on a typical workpiece with a double-wall structure and a nickel-based single crystal blade.