Electrode Path Planning For Numerical Control EDM Of Double-row Shrouded Integral Turbine Blisk

Turbine blisk with integral structure can improve the efficiency of the engine,which is the inevitable trend of the new generation of high performance aerospace engines.The double-row shrouded integral turbine blisk is a new structural component designed for a new generation of high performance liquid rocket engines.It has the characteristics of narrow structure channel,twisted blade,poor machinability of material and small distance between two stages.Multi-axis NC EDM is regarded as an effective machining approach for producing shrouded blisks.The key is to plan an interference-free electrode feed path.In this paper,the key problems in numerical control EDM of the double-row shrouded integral turbine blisk are studied,including geometric modeling,electrode design and motion path planning.The structure of the double-row shrouded integral turbine blisk is decomposed,and the modeling methods of straight blade and twisted blade are mainly discussed.The hub,crown and blade entity are constructed respectively,and the entities are merged by Boolean operation to realize the three-dimensional geometric modeling of the double-row shrouded integral turbine blisk.According to the blade channel to complete the initial design of the electrode,the optimization methods of shape electrode,such as height reduction design,thickness reduction design,axial splitting and radial splitting,as well as the design of electrode pre-loss zone,are proposed.A reverse search algorithm is proposed to plan the feed motion path of the double-row shrouded integral turbine blisk by forming electrode.The electrode feed path planning problem is discretized.Through preliminary optimization and deep optimization,the electrode is translated and rotated in the blade channel to obtain the optimal thickness of the formed electrode and its optimal position and attitude,and the NC path is generated to solve the difficult problem of NC EDM path planning for the double-row shrouded integral turbine blisk.Based on the above research,a special CAD/CAM system for multi-axis NC EDM of the double-row shrouded integral turbine blisk is developed.Finally,the double-row shrouded integral turbine blisk designed by a aerospace company is simulated by the simulation system.The simulation results show that the electrode and the motion path designed by the method proposed in this paper are correct and feasible.