| Shrouded blisk components in aerospace engines play an extremely important role in improving the efficiency of the whole system and enhancing engine reliability.With the complicated geometry configuration,the channel of a blisk component is generally twisted and half-opened,which certainly brings enormous challenges for machining.According to practical experience,multi-axis numerically controlled electrical discharging machining is regarded as the best method for shrouded blisks machining,due to its good tool reachability and high machining precision.This dissertation focuses on several NC-EDM key technologies of shrouded blisks,such as electrode wear prediction,electrode simplify method and ganged-electrode mechanism analysis.In order to solve the problem of electrode wear prediction in EDM,the relationship among electrode wear,feeding direction and geometrical feature was analyzed and achieved by abundant experiments.Based on the corresponding electrode wear prediction model built in this dissertation,a method for the prediction of electrode wear was also proposed.The effectiveness of the method was verified by experiments.Considering the low machining efficiency of EDM,an electrode simplification method was proposed for shrouded blisk rough machining,in which the simplified electrode feeds along linear axis and removes as much the unwanted material on the blisk as possible.According to experiment results,the efficiency increased by more than 25% for single channel machining.To find the reason why ganged-electrode improves the machining efficiency,the effect of electrodes number on the utilization of power pulse was demonstrated by analyzing microscopic discharging mechanism.Besides,the optimization strategy of machining parameters for gangedelectrode method was proposed at the same time.Assisted by multi-axis EDM machine tool and CAD/CAM system,series of sample components have been machined,which proved the validity of the methods proposed in this dissertation. |
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