Effects Of Debris Evacuation And Servo Speed On The Edm Process Of Integral Shrouded Blisk

Integral shrouded blisk is one of the most important kinds of parts in aerospace engines.The performance and reliability of the engine depend heavily on the blisk.Due to its extremely harsh working environment,the integral shrouded blisk is made of difficult-to-cut material with complex profile and semi-closed structure.Thus,the processing of such parts is a challenge to the industry.At present,the best processing method for integral shrouded blisk at home and abroad is multi-axis numerically controlled EDM.This method has the advantages of good electrode accessibility and high processing precision,but the low machining efficiency is still the main problem.In order to solve this problem,this dissertation focuses on the debris evacuation and electrode servo speed optimization to improve the machining efficiency in the EDM process of integral shrouded blisk.In order to solve the problem of low EDM machining efficiency due to poor debris evacuation condition,numerical simulation and experimental study of regular flushing and flushing with pre-machined holes were conducted.The effect of the flushing parameters,jump motion and holeflushing were simulated,and the simulation results were verified by the experiments.The flushing parameters selecting method for blisk EDM processing was given according to the results of the simulation and the experiment.The method improved the debris evacuation effect and the machining efficiency of the blisk increased by 5% through the optimization of the flushing parameters.Considering the limited improvement of the debris evacuation effect by flushing method,a new debris evacuation method named hole-sucking method was proposed,in which the working fluid was sucked from the opposite side of the flow channel via pre-machined holes.The new method was realized through the pumping system.The influence of the premachined hole parameters on debris evacuation effect was analyzed through simulation and experiment.Pre-machined hole parameters designing method and its processing method were also given.The machining process of certain integral shrouded blisk revealed that the hole-sucking debris evacuation method greatly improved the debris evacuation effect,and a machining efficiency increase of 22% was achieved.As the instability of the discharge state affects the EDM efficiency,the servo sensitivity parameters that determine the servo speed in the servo control system were studied.The relationships among servo sensitivity,machining efficiency and surface roughness were analyzed.The servo sensitivity selection method under given debris evacuation condition was given to improve the machining efficiency in both rough machining and finish machining.With this method,the efficiency of the EDM of blisk improved 25% while the surface roughness declined 7.3%.