电火花多电极高效加工GH4169D闭式整体叶轮

High efficiency machining of GH4169D closed integral impeller by multi-electrode EDM

叶轮是飞机发动机的重要核心零/部件之一,镍基高温合金GH4169D闭式整体叶轮是其中加工难度最大的一种。传统电火花加工(Electrical Discharge Machining,EDM)闭式整体叶轮,主要受限于加工效率低,成品率低。为此,创新研发了电火花多电极多变量自适应控制系统,根据加工过程中的放电状态和加工环境,自适应调节间隙电压、抬刀周期和脉冲间隔时间,既保证了多电极同时加工的条件,又可以维持高效加工的极间加工环境。在大能量放电条件下,采用多个电极同时加工闭式整体叶轮的多个流道型面;在小能量放电条件下,通过分步加工的方法,修整粗加工后的流道型面,这样既可以提高加工效率又可以满足加工表面质量的要求。实验结果显示,在多电极粗加工中,单个流道型面加工平均用时仅需17 min,相比单电极加工单个流道型面,效率提高了10倍左右。在多电极精加工中,叶盆和叶背表面粗糙度分别仅为1.246和1.487μm。该结果表明了电火花多电极多变量自适应控制系统可广泛应用于闭式整体叶轮的加工制造中,具有十分重要的意义。

The impeller is one of the important core parts of the aircraft engine,and the nickel-base high temperature alloy GH4169D closed integral impeller is the most difficult one to process.The traditional EDM closed integral impeller is mainly limited by low processing efficiency and low yield.Therefore,a multi-electrode and multi-variable adaptive control system for EDM was innovated and developed.According to the discharge state and processing environment during the machining process,the gap voltage,tool lifting period and pulse closing time can be adjusted adaptively,which not only ensures the conditions for simultaneous machining of multi-electrodes,but also maintains an efficient inter-electrode processing environment.Under the condition of high energy discharge,multi-electrodes were used to process multiple flow paths of closed integral impeller at the same time.Under the condition of small energy discharge,the flow path profile after rough machining was trimmed by step machining method,which can not only improve the processing efficiency but also meet the requirements of machining surface quality.The experimental results show that in multi-electrode rough machining,the average processing time of single flow path profile is only 17 minutes,which is about 10 times higher than that of single electrode machining.In the multi-electrode finishing process,the surface roughness of the blade basin and the blade back is only 1.246 and 1.487μm,respectively.The results show that the EDM multi-electrode and multi-variable adaptive control system can be widely used in the machining and manufacturing of closed integral impeller,which is of far-reaching significance.