Electrode feeding path searching for 5-axis EDM of integral shrouded blisks

With a closed shroud on the top of their blades, the so-called integral shrouded blisks gained more and more applications in turbine engines. 5-axis electrical discharge machining (EDM) is regarded as the most effective approach for integral shrouded blisks machining. The tool electrode is shaped and reduced according to the profile of the flow channels to get enough space for electrode feeding. The key of EDM of integral shrouded blisks is to search an interference-free and optimized electrode feeding path. In this paper, a new electrode feeding path searching method called tangent tracking was proposed. Based on the dynamic programming methodology, the electrode feeding path searching process is decomposed into a number of electrode attitude optimization subproblems. Each subproblem can be further divided into two phases: pre-optimization and re-optimization. The purpose of electrode attitude pre-optimization is to make the tangent vector of the electrode centre curve coincide with that of the flow channel centre curve at the flow channel's outlet section. If the electrode interferes with the blisk in the pre-optimization, the re-optimization needs to be conducted in order to find an interference-free attitude in the vicinity of the pre-optimized result. The tangent tracking method is validated by an integral shrouded blisk machining experiment.