Applied Fundamental Research On Precision And Efficient Electrical Discharge Machining Of Cowled Integral Impeller

As the key part of energy conversion and transmission, cowled impeller is widely used in airspace engine, weaponry and advanced turbine machinery. With the integration, miniaturization and lightweight of modern machinery, cowled impeller is usually designed into integral structure. In this design the out coronary, blade and hub are integral and the channel between blades is semi-closed which give the processing a poor accessibility. Furthermore, the difficult-to-cut materials existing in some parts such as titanium alloy and superalloy make the integral manufacture more difficult.Based on the research and application from the practice of NC- electrical discharge machining(NC-EDM) of cowled integral impeller, researches on efficient EDM of cowled integral impeller with cylindrical out coronary inner torus,cylindrical hub out torus and freeform blade surface were carried out. Processing scheme which focuses on multi-channels simultaneous forming with group cathodes was proposed. The key technologies including selection of preprocessing, movement scheme of group electrodes, forming process of channel between blades, structure design of group electrodes, channels amount of simultaneous processing and selection of process parameters based on general precision EDM forming machine were mainly researched.In order to improve the efficiency and accuracy of electrode design furtherly, the secondary development on UG was carried out and digital platform of EDM was built combined with the EDM process and digital manufacturing of cowled impeller, which realized the automatic search of electrode trajectory, automatic correction of the profile, simulation of the motion and error analysis of the profile/position.Based on the research above, a typical cowled integral impeller meeting the design requirement was trial-produced and technical scheme is systemic verified. In this work, the effective method for efficient EDM process of cowled integral impeller was explored, and the digital platform of EDM was developed to improve the design accuracy of electrode and trajectory and reduce the previous experiments amount. A foundation for the engineering application of cowled integral impeller EDM technology was laid by this study.