Drilling of film cooling holes by a EDM/ECM in situ combined process using internal and side flushing of tubular electrode
Drilling of film cooling holes by a EDM/ECM in situ combined process using internal and side flushing of tubular electrode
复制标题
使用管状电极的内部和侧面冲洗，通过 EDM/ECM 原位组合工艺钻出薄膜冷却孔
DOI：
10.1007/s00170-015-7575-3
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发表时间：
2016-03-01
影响因子：
3.4
通讯作者：
Zhu, Yun
中科院分区：
文献类型：
--
作者：
Zhang, Yan;Xu, Zhengyang;Zhu, Yun
为了允许非常高的涡轮机入口气体温度，在燃气涡轮机发动机中广泛应用薄膜冷却孔。由于对加工效率和表面质量的高要求，在难加工材料上加工气膜冷却孔的难度极大。提出了一种管状电极电火花高速钻削/电解加工原位复合工艺。在该方法中，有效地采用放电加工（EDM）来形成孔，随后通过电化学溶解从加工表面去除由此产生的重铸层。在这项研究中，一个管状电极和一个专门设计的冲洗装置，与内部和侧面冲洗同时进行，使电火花加工和电解加工可以结合在原位。在镍基高温合金上研究了该技术的性能。为了实现最佳性能，确定了电火花加工参数（峰值电流、脉冲持续时间和脉冲间隔）的理想值。电解加工是用来去除电火花加工产生的粗糙表面的。与电火花加工相比，电火花/电解原位复合加工提高了孔的表面质量，消除了再铸层。结果表明，该复合工艺适用于无重铸层的气膜孔加工。
To allow very high turbine inlet gas temperatures, film cooling holes are widely applied in gas turbine engines. Owing to the requirements of high machining efficiency and surface quality, the fabrication of film cooling holes in difficult-to-machine materials is extremely difficult. A tubular electrode electro-discharge high-speed drilling/electrochemical machining (ECM) in situ combined process has been proposed for this task. In this approach, electro-discharge machining (EDM) is efficiently employed to form the holes, following which the recast layer thereby generated is removed from the machined surface by electrochemical dissolution. In this study, a tubular electrode and a specially designed flushing device are used, with internal and side flushing being performed at the same time so that EDM and ECM can be combined in situ. The performance of the technique is investigated on a nickel-based superalloy. To achieve the best performance, the ideal values of EDM parameters (peak current, pulse duration, and pulse interval) are determined. The ECM is employed to remove the rough surface produced by the EDM. Compared with EDM alone, it is found that the EDM/ECM in situ combined process improves the surface quality of the holes and removes the recast layer. It is confirmed that the combined process is suitable for producing film cooling holes without a recast layer.