A framework for accuracy enhancement in milling thin-walled narrow-vane turbine impeller of NiAl-based superalloy

Abstract

Impeller with narrow-vane is a typical thin-walled structural part of the turbine engine. The high-accuracy requirement for the impeller is difficult to achieve in the machining process due to its low structural stiffness and narrow machining domain. This paper proposes a framework for enhancing the milling accuracy of the thin-walled narrow-vane turbine impeller, which is made of NiAl-based superalloy. The proposed framework consists of a machinability study of the impeller material, a machining deformation analysis, and an error compensation. By studying the milling force and tool wear behavior experimentally, the machinability study yielded optimized process parameters for machining NiAl-based superalloy. A cantilever beam–based tool deformation model and a finite element analysis method model were developed respectively to analyze and predict the deformation of the milling tool in machining the impeller. A flexible and iterative compensation method was studied for decreasing the machining error when milling the impeller. The effectiveness of the proposed framework has been validated experimentally. The results show that the milling accuracy of the turbine impeller has been enhanced significantly.