Study on modal analysis and chip breaking mechanism of Inconel 718 by ultrasonic vibration-assisted drilling

In this study, both theoretical and experimental research was conducted to investigate the role played by a difficult-to-machine material, Inconel 718, in improving the surface finish quality in drilling holes. Ultrasonic vibration technology was applied to assist with the drilling process. An axial ultrasonic vibration-assisted drilling (UAD) system was designed to determine the structural relationships between different component parts, based on which an axial UAD model was established. Abaqus finite element software was applied to perform model simulation and an analysis was conducted of the structure to find its optimal natural frequency and vibration mode. The conditions for complete geometric chip breaking based on the mechanisms of UAD and chip breaking, as well as pre-set parameters, were inferred and the theoretical domain of complete geometric chip breaking was mapped. Subsequently, a range of different parameters was applied to conduct experiments on the drilling process, from which it was established that the characteristics of chipping satisfy the conditions required for complete geometric chip breaking. Finally, under the circumstances where the parameters for the drilling process are identical and chip breaking conditions are met, UAD was found to be advantageous over conventional drilling (CD) as the former produces a more apparent chip breaking effect. Additionally, UAD can reduce the Ra value and abrasion of cutting tools, thus improving the quality of the hole drilling process.