Design and grindability assessment with cup shaped electroplated CBN wheel grinding turbine disc slots of powder metallurgy superalloy FGH96

Abstract

The machining surface integrity of aero-engine turbine disc slots has a significant impact on their fatigue life and service performance, and achieving efficiency and high-precision machining is still a great challenge. The high machining requirements of future aeroengine turbine disc slots will be difficult to satisfy using the broaching method. In addition, existing methods of slot machining face difficulties in ensuring surface integrity. This study explored a cup shaped electroplated Cubic Boron Nitride (CBN) abrasive wheel for profile grinding the turbine disc slots of FGH96 powder metallurgy superalloy. The matrix structure of the cup shaped abrasive wheel was designed and verified. A profile grinding experiment was conducted for fir-tree slots on a five-axis machining center. The accuracy and the surface integrity were analyzed. Results show that the key dimension detection results of the slots were within the allowable tolerance range. Meanwhile, an average surface roughness Ra of 0.55 μm was achieved, the residual stress was compressive, the plastic deformation layer thickness was less than 5 μm, and the hardening layer thickness was less than 20 μm. The research findings provide a new approach to machining the slots of aviation engine turbine discs and guidance for the high-quality processing of complex components.