Counter-rotating electrochemical machining of a combustor casing part using a frustum cone-like cathode tool

Abstract

An aero-engine casing is a thin-walled revolving part with many complex convex structures on its outer surface. It is usually made of difficult-to-cut materials such as nickel-based super alloy or titanium alloy, and may have a material removal ratio as high as 60–80%. Thus, manufacturing aero-engine casings via conventional machining methods is time-consuming and expensive. In this paper, a frustum cone-like cathode tool is used to manufacture a combustor casing part via counter-rotating electrochemical machining (CRECM). A mathematical model based on the CRECM process is established. A cathode design method is proposed based on optimizing the edge points of the concave window. The methods used to determine the three main frustum cone-like cathode tool parameters: the radius, the half cone angle, and the concave window angle, are described in detail. An experiment is performed using the frustum cone-like cathode tool in which a combustor casing part with complex convex structures is successfully machined. The surface is smooth and contains no flow tracks or rib-like remnants. Convex structures with various shapes can be fabricated using a single frustum cone-like cathode tool. The edges of the convex structures are trenchant and the dimensions of the machined convex structure meet the tolerance requirements. This indicates that the proposed CRECM process offers a superior machining ability to manufacture hard-to-machine combustor casing parts.