Prediction Of Electrical Discharge Machining Time Of Integral Shrouded Blisk

The integral shrouded blisk is the core component of the aerospace engine and directly affects the performance of the engine.Due to the extremely severe high-temperature and high-pressure environment where it is used,its materials are usually superalloys,coupled with its semi-closed and highly twisted channel geometry,which makes traditional milling difficult,so that EDM become the preferred machining.For the needs of production arrangement,the prediction of machining time is a very important part.However,due to the numerous influencing factors of EDM,it is difficult to predict the machining time of integral shrouded blisk,which restricts the development of the technology of integral shrouded blisk EDM in automation.In view of this problem,this thesis focuses on the factors influencing EDM time,EDM time algorithm of integral shrouded blisk and the development of simulation software for machining time prediction.Due to the numerous influencing factors of EDM,the machining time of the part is not only related to its feed trajectory,but also related to the discharge state in the process.The material removal amount of the workpiece is in a non-linear relationship with the machining time,especially for the parts with complex shapes,so it is difficult to predict EDM time.In order to solve this problem,a method of obtaining stable machining parameters and using gradient descent to predict machining time is proposed.First of all,through the DOE of designing the parameters of electrical machining,and combining with the simulation of jump motion and flushing,the method of obtaining stable processing parameters was explored.After that,the stable processing parameters and the rod electrode with a diameter of 5mm and 15 mm were used to carry out the processing experiment with a depth of 5mm.The errors were 3.3% and 4.9%,proving the feasibility of the prediction method.The EDM of integral shrouded blisk needs to adopt the multi-axis machining,but the machining efficiency of each axis is greatly different,which makes the rule that the material removal rate changes with the processing depth under a single servo axis no longer applicable.To solve this problem,a weighted average algorithm based on machining trajectory is proposed.According to the feed quantity of each servo axis,the weight of each servo axis was determined.According to the weight and the machining efficiency of each servo axis,the variation law of material removal rate with machining depth under the condition of multi-axis EDM was obtained,and the machining time was predicted.The experimental results show that the error of the predicted feed time is 0.5% and the error of the total machining time is 1.8%,which can effectively predict the EDM time of the integral shrouded blisk.In order to choose the time of change the electrode by matching machining time and electrode wearing,computer simulation is needed.Aiming at the problems,the software module of machining time prediction is developed.The time prediction simulation by using 10 mm diameter rod electrode with feed depth of 6mm and 8mm was carried out machining,with errors of 2.4% and 6.0%.The integral shrouded blisk time prediction simulation shows the feed error and total time error are 5.1% and 2.6%respectively.This shows the time prediction software can predict the electrode morphology according to different machining time and provide guidance for electrode dressing and replacement.