US-20260125982-A1 - METHODS OF MACHINING TURBINE COMPONENTS USING A REFERENCE SURFACE

US20260125982A1US 20260125982 A1US20260125982 A1US 20260125982A1US-20260125982-A1

Abstract

A method of repairing a turbine blade includes positioning the turbine blade within a system including a machining tool; determining a first distance between a surface of a first PSP attached to a tip shroud of the turbine blade and a datum surface formed in the tip shroud; removing the first PSP from the tip shroud; coupling a second PSP to the tip shroud; and machining a surface of the second PSP using the machining tool, wherein machining the second PSP surface includes controlling movement of the machining tool using the datum surface as a reference, such that the machined second PSP surface is located the first distance from the datum surface.

Inventors

Quyen Doan
Richard David Coen
Brently A. Lord

Assignees

GE VERNOVA INFRASTRUCTURE TECHNOLOGY LLC

Dates

Publication Date: 20260507
Application Date: 20251126

Claims (14)

1 . A method of repairing a turbine blade that includes a tip shroud and a first pre-sintered preform (PSP) attached to the tip shroud, the method comprising: positioning the turbine blade within a system including a machining tool; determining a first distance between a surface of the first PSP and a datum surface formed in the tip shroud; removing the first PSP from the tip shroud; coupling a second PSP to the tip shroud; and machining a surface of the second PSP using the machining tool, wherein machining the second PSP surface comprises controlling movement of the machining tool using the datum surface as a reference, such that the machined second PSP surface is located the first distance from the datum surface.
2 . The method of claim 1 , further comprising machining, using the machining tool, the datum surface in the tip shroud such that the datum surface is located the first distance from the first PSP surface.
3 . The method of claim 1 , wherein determining the first distance comprises machining the datum surface in the tip shroud and measuring a distance between the datum surface and the first PSP surface.
4 . The method of claim 1 , wherein determining the first distance comprises determining a pre-defined first distance and machining the datum surface in the tip shroud the pre-defined first distance from the first PSP surface.
5 . The method of claim 1 , wherein coupling the second PSP to the tip shroud comprises coupling the second PSP and the tip shroud securely together by one of brazing and welding.
6 . The method of claim 1 , further comprising coupling a third PSP to the tip shroud and, after machining the second PSP surface, machining a surface of the third PSP to a second distance measured between the machined second PSP surface and the machined third PSP surface.
7 . The method of claim 6 , wherein machining the third PSP surface to the second distance comprises machining the third PSP surface to a pre-defined second distance measured between the machined second PSP surface and the machined third PSP surface.
8 - 14 . (canceled)
15 . A method of repairing a turbine blade that includes a tip shroud, and a first pre-sintered preform (PSP) and a second PSP attached to the tip shroud, the method comprising: positioning the turbine blade within a system including a machining tool; controlling the machining tool to machine a datum surface in the tip shroud; removing the first and second PSPs from the tip shroud; coupling a third PSP and a fourth PSP to the tip shroud; controlling the machining tool to machine the third PSP using the datum surface as a reference; and controlling the machining tool to machine the fourth PSP after machining the third PSP.
16 . The method of claim 15 , wherein controlling the machining tool to machine the datum surface comprises controlling the machining tool to machine the datum surface using a surface of the first PSP as a reference.
17 . The method of claim 16 , wherein controlling the machining tool to machine the datum surface comprises controlling the machining tool to machine the datum surface a first distance from the first PSP surface.
18 . The method of claim 17 , wherein controlling the machining tool to machine the third PSP comprises controlling the machining tool to machine the third PSP using the datum surface as a reference and based on the first distance.
19 . The method of claim 17 , wherein controlling the machining tool to machine the third PSP comprises controlling the machining tool to machine the third PSP to the first distance from the datum surface.
20 . The method of claim 15 , wherein controlling the machining tool to machine the fourth PSP comprises controlling the machining tool to machine the fourth PSP based on a distance between the first and second PSPs.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a divisional of U.S. application Ser. No. 18/475,650 filed Sep. 27, 2023 which claims the benefit of U.S. Provisional Ser. No. 63/411,531 filed Sep. 29, 2022, the disclosures of which are hereby incorporated herein by reference in its entirety. BACKGROUND The field of the disclosure relates generally to turbine blades used with rotary machines, and more particularly to methods of manufacturing and repairing turbine blades having a pre-sintered preform layer wherein a reference surface is used for machining the pre-sintered preform layer. At least some known rotary machines include at least one rotor assembly coupled to a rotor shaft. The rotor assembly includes a plurality of circumferentially-spaced blades that extend radially outward towards a stationary casing that defines a portion of a hot gas flow path through the rotary machine. A plurality of stationary vanes (or nozzles) are coupled to the casing in a circumferential array such that the stationary vanes extend radially inwardly into the flow path. The stationary vanes and rotating blades are arranged in alternating rows such that a row of vanes and the immediate downstream row of blades form a “stage” of the rotary machine. The vanes direct the hot gas flow towards the downstream row of blades wherein the blades extract energy from the flow, thereby developing the power necessary to drive a rotor and/or an attached load, e.g., a generator. For example, but not by way of limitation, the rotor assembly may be part of a steam turbine, or part of a compressor or turbine section of a gas turbine engine. Some turbine hot gas path components may include one or more sheets of material applied over a portion or portions of the underlying component. For example, during pre-sintered preform (PSP) fabrication, one or more sheets of material are brazed onto at least some turbine components, such as a shrouded blade or a nozzle. The PSP sheets are usually overlaid across the component, and then brazed onto the component to form an external surface. Typically, the sheets are substantially flat or include a curvature that is generally similar to the overall geometry of the component surface to which they become attached, although, through pressure, bending, and the like, these flat sheets may be conformed to the underlying component surface during the attachment process. At least some turbine components include shrouds at the outer extremity of the airfoil. The shrouds are typically designed with an interlocking feature which enables each component to be interlocked at its shroud with an immediately-adjacent component when such components are installed about the circumference of a turbine disk. This interlocking feature assists in preventing the airfoils from vibrating, thereby reducing the stresses imparted on the components during operation. Turbine hot gas path components are typically made of nickel-based superalloys or other high temperature superalloys designed to retain high strength at high temperature. However, the material used in fabricating the shroud of the turbine component and the interlocking feature may not be of a sufficient hardness to withstand prolonged exposure to the wear stresses and/or rubbing that may occur during start-up and shut down of a turbine engine. To improve the wear at these locations, a hardface pre-sintered preform (PSP) may be brazed or welded to the component to serve as a wear surface. The hardface material protects each respective component and associated shroud from wear arising from frictional contact during operation, when the turbine components are under centrifugal, pressure, thermal, and/or vibratory loading. Conventional fabricating and/or reconditioning of a turbine component including a hardface PSP typically requires removing an existing PSP from the component, re-brazing or re-welding a new hardface PSP onto the component, and machining the new hardface PSP to a targeted profile. Machining the hardface PSP is typically performed using a multi-axis computer numerically controlled (CNC) unit. CNC units enable movement of the cutting tool along a number of axes, including X-, Y-, and Z-axes, as well as rotational axes. In machining the hardface PSP, movement of the CNC unit is guided by a coordinate system that relies on data gathered from the component to ensure the targeted profile of the hardface PSP is achieved. Typically, a separate location on the component (e.g., a midspan shroud) is used as an origin (a reference point) and relative rotation and/or translation of a portion of the component to which the hardface PSP is applied (e.g., a tip shroud of the airfoil) is calculated relative to the origin in order to derive a coordinate system for guiding the CNC unit. The data is gathered and saved prior to removing an existing PSP. After the new hardface PSP is applied, the reference point is probed and the saved data is analyzed to determine final trans