Method of machining turbine component using reference surface

Abstract

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

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 411,531 filed on September 29, 2022, the disclosure of which is hereby incorporated by reference in its entirety. Background Art

[0003] The field of the present disclosure relates generally to turbine blades for use with rotating machines, and more particularly to methods of manufacturing and repairing turbine blades having a pre-sintered preform layer in which a reference surface is used to machine the pre-sintered preform layer.

[0004] 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 extending radially outward toward a stationary housing that defines a portion of a hot gas flow path through the rotary machine. A plurality of stationary blades (or nozzles) are coupled to the housing in a circumferential array so that the stationary blades extend radially inward into the flow path. The stationary blades and rotating blades are arranged in alternating rows so that the blade rows and the blade rows immediately downstream form a "stage" of the rotary machine. The blades direct the hot gas flow toward the downstream blade row, where the blades extract energy from the flow to generate the power required to drive the rotor and / or an attached load (e.g., a generator). For example, but not limited to, the rotor assembly may be part of a steam turbine, or part of a compressor or turbine section of a gas turbine engine.

[0005] Some turbine hot gas path components may include one or more sheets of material applied over one or more portions of an underlying component. For example, during pre-sintered preform (PSP) fabrication, one or more sheets of material are brazed to at least some turbine components, such as shrouded blades or nozzles. Typically, a PSP sheet is superimposed on the component and then brazed to the component to form an outer surface. Typically, although these sheets are substantially flat, or include a curvature that is substantially similar to the overall geometry of the component surface to which they are attached, these sheets can be conformed to the underlying component surface during the attachment process by pressure, bending, etc.

[0006] At least some turbine components include shrouds located at the outer ends of the airfoils. These shrouds are typically designed with interlocking features that allow such components to interlock with adjacent components at their shrouds when each component is installed around the circumference of the turbine disk. The interlocking features help prevent airfoil vibration, thereby reducing stresses placed on the components during operation.

[0007] Turbine hot gas path components are typically made of nickel-based superalloys or other high-temperature superalloys designed to maintain high strength at high temperatures. However, the materials used to make the shrouds and interlocking features of the turbine components may not have sufficient hardness to withstand long-term exposure to wear stresses and / or friction that may occur during the startup and shutdown of the turbine engine. To improve wear at these locations, a hardface pre-sintered preform (PSP) can be brazed or welded to the component to serve as a wear surface. When the turbine components are under centrifugal loads, pressure loads, thermal loads, and / or vibration loads, the hardface material protects each corresponding component and the associated shroud from wear caused by frictional contact during operation.

[0008] Conventional manufacture and / or repair of turbine components that include a hardface PSP typically requires removing the existing PSP from the component, re-brazing or re-welding a new hardface PSP to the component, and machining the new hardface PSP to a target profile. Machining of the hardface PSP is typically performed using a multi-axis computer numerical control (CNC) unit. The CNC unit enables the cutting tool to move along multiple axes (including the X-axis, the Y-axis, and the Z-axis) as well as a rotational axis. When machining the hardface PSP, in order to ensure that the target profile of the hardface PSP is achieved, the movement of the CNC unit is guided by a coordinate system that relies on data collected from the component.

[0009] Typically, a single location on a component (e.g., a mid-span shroud) is used as an origin (reference point), and the relative rotation and / or translation of a portion of the component to which a hardface PSP is applied (e.g., a tip shroud of an airfoil) is calculated relative to the origin in order to derive a coordinate system for guiding the CNC unit. Data is collected and stored before the existing PSP is removed. After the new hardface PSP is applied, the reference points are detected and the stored data is analyzed to determine the final translation and rotation derived from the coordinate system transformation to guide the CNC unit when machining the new PSP. Conventional methods such as these may be limited because the method relies on the use of reference points that are not located on the portion of the component to which the PSP is applied. Therefore, during the method, the translation and rotation data derived from the coordinate system transformation requires a relatively high degree of accuracy at the same location on the component during initial and final machining and during data storage. Errors in machining hardface PSPs may be amplified due to indirect or inaccurate positioning, multiple detections, transformations, and / or errors in data storage.

[0010] Therefore, there is a need to simplify the manufacture and / or repair of turbine components, including machining pre-sintered preforms, so that the process can be repeated and reduce and / or eliminate the above-mentioned problems. Summary of the invention

[0011] In one aspect, a method of repairing a turbine blade is provided. The turbine blade includes a tip shroud and a first pre-sintered preform (PSP) attached to the tip shroud. The method includes positioning the turbine blade within a system including a machining tool; determining a first distance between a surface of the first PSP and a reference surface formed in the tip shroud; removing the first PSP from the tip shroud; coupling a second PSP to the tip shroud; and machining the surface of the second PSP using the machining tool, wherein machining the second PSP surface includes controlling movement of the machining tool using the reference surface as a reference so that the machined second PSP surface is located at the first distance from the reference surface.

[0012] In another aspect, a method of repairing a turbine component is provided. The turbine component includes a first hardface structure and a second hardface structure. The method includes positioning the turbine component within a system including a machining tool; determining a first distance between a surface of the first hardface structure and a reference surface formed in the turbine component; removing the first hardface structure and the second hardface structure from the turbine component; coupling a third hardface structure to the turbine component and coupling a fourth hardface structure to the turbine component; machining the surface of the third hardface structure using the machining tool, wherein machining the surface of the third hardface structure includes using the reference surface as a reference to control movement of the machining tool so that the machined surface of the third hardface structure is located at a first distance from the reference surface; and machining the surface of the fourth hardface structure using the machining tool to a second distance measured between the machined surface of the third hardface structure and the machined surface of the fourth hardface structure.

[0013] In another aspect, a method of repairing a turbine blade is provided. The turbine blade includes a tip shroud and a first pre-sintered preform (PSP) and a second PSP attached to the tip shroud. The method includes positioning the turbine blade within a system including a machining tool; controlling the machining tool to machine a reference surface in the tip shroud; removing the first PSP and the second PSP 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 reference surface as a reference; and after machining the third PSP, controlling the machining tool to machine the fourth PSP. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] These and other features, aspects and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings, in which like characters refer to like parts throughout the several views, and in which:

[0015] Figure 1is a schematic diagram of an exemplary rotating machine;

[0016] Figure 2 It is available with Figure 1 A front view of an exemplary turbine blade for use with a rotating machine;

[0017] Figure 3 and Figure 4 They are Figure 2 front and rear perspective views of a tip shroud of a turbine blade;

[0018] Figure 5 An exemplary process for manufacturing a turbine blade is shown, the turbine blade including attachment to Figure 3 and Figure 4 a pre-sintered preform of a tip shroud; and

[0019] Figure 6 Shown is the method for executing Figure 5 Schematic diagram of an exemplary system of the process.

[0020] Corresponding reference numerals used in all drawings represent corresponding parts. Unless otherwise specified, the drawings provided herein are intended to illustrate the features of the embodiments of the present disclosure. It is believed that these features are applicable to a wide variety of systems including one or more embodiments of the present disclosure. Therefore, the drawings are not intended to include all conventional features required for practicing the embodiments disclosed herein known to those of ordinary skill in the art. DETAILED DESCRIPTION

[0021] Embodiments described herein provide methods for manufacturing (e.g., repairing) a component for a rotating machine (such as, for example, a blade for a turbine engine). A turbine blade includes a tip shroud and a first pre-sintered preform (PSP) attached (e.g., brazed or welded) to the tip shroud. A reference surface is formed (e.g., machined) in the tip shroud so that the reference surface is oriented substantially parallel to an outer surface defined by the first PSP. The reference surface is used as a reference point for machining the PSP subsequently attached to the tip shroud. In particular, the reference surface is located at a distance from the outer surface defined by the first PSP. The distance is determined (e.g., can be predetermined, fixed, or determined in situ). The first PSP is then removed during the repair process, for example, in the case where the turbine blade was previously used during operation of the turbine engine and the first PSP experienced operational wear. Then, a second PSP is coupled to the tip shroud at the same position as the removed first pre-sintered preform. The second PSP is then machined to a target profile so that the second PSP defines the outer surface of the component.

[0022] Advantageously, the reference surface is used as an origin (reference point) during machining of the second PSP to facilitate machining the second PSP to a profile substantially identical to that of the first PSP. For example, the second PSP is machined such that an outer surface defined by the second PSP substantially matches an outer surface defined by the first PSP. In addition, the outer surface defined by the second PSP is oriented substantially parallel to the reference surface after machining and is substantially located at the same distance from the reference surface as the outer surface defined by the first PSP. Compared to conventional methods of repairing turbine blades having a PSP attached to a tip shroud, the embodiments described herein help reduce errors in machining the PSP and improve accuracy and repeatability by using a reference surface formed in the tip shroud.

[0023] Unless otherwise indicated, approximate language as used herein, such as "substantially", "substantially" and "about" indicate that as will be recognized by one of ordinary skill in the art, the term so modified may apply only to an approximate degree, rather than an absolute or perfect degree. Therefore, the value modified by one or more terms (such as "about", "approximately" and "substantially") is not limited to the specified precise value. In at least some cases, the approximate language may correspond to the precision of the instrument used to measure the value. In addition, unless otherwise indicated, the terms "first", "second", etc. are used only as labels in this article and are not intended to impose order, position or hierarchical requirements on the items to which these terms refer. In addition, for example, a reference to a "second" item does not require or exclude the existence of, for example, a "first" or lower numbered item or a "third" or higher numbered item. As used herein, the term "upstream" refers to the front end or inlet end of a rotating machine, and the term "downstream" refers to the downstream end or outlet end of a rotating machine.

[0024] As used herein, the phrase "hardface structure", "pre-sintered preform" or "PSP" refers to a structure, component or composition that improves the wear resistance of a component to which the hardface structure or PSP is attached (e.g., brazed or welded). The hardface structure or pre-sintered preform may be a sintered powder metallurgy product comprising a homogeneous mixture of a superalloy matrix material and a brazing alloy powder. The PSP brazing material may include a superalloy. The term "superalloy" refers to an alloy having many superior physical properties compared to conventional alloys, such as but not limited to high mechanical strength and high resistance to thermal creep deformation. Exemplary superalloys include but are not limited to iron-based superalloys, nickel-based superalloys, or cobalt-based superalloys. In some examples, in addition to the base metal, the PSP brazing material may also include at least one of aluminum (Al), titanium (Ti), chromium (Cr), tungsten (W), molybdenum (Mo), rhenium (Re), tantalum (Ta), silicon (Si), boron (B), or iron (Fe).

[0025] As used herein, "X-axis," "Y-axis," and "Z-axis" refer to axes that are perpendicular to each other (i.e., each is orthogonal to the other) and are used to describe a three-dimensional aspect or orientation. The description of an element of the subject matter disclosed herein is not limited to one or more specific axes used to describe the three-dimensional orientation of the element. In other words, the axes can be interchangeable when referring to the three-dimensional aspects of the disclosed subject matter.

[0026] Figure 1 1 is a schematic diagram of an exemplary rotary machine 110. In the exemplary embodiment, rotary machine 110 is a gas turbine engine. Alternatively, rotary machine 110 may be any other turbine engine and / or rotary machine, including but not limited to a steam turbine engine, a gas turbofan aircraft engine, other aircraft engines, a wind turbine, a compressor, and / or a pump. In the exemplary embodiment, gas turbine 110 includes a rotor assembly 112 including a shaft 114 and a plurality of axially spaced rotor wheels 118.

[0027] A plurality of rotating blades 120 are coupled to each rotor wheel 118 such that each blade 120 extends radially outward from each respective rotor wheel 118. More specifically, the blades 120 are arranged in rows extending circumferentially around each wheel 118. A plurality of stationary blades 122 extend circumferentially around the shaft 114 such that each row of stationary blades 122 is between a pair of axially adjacent rows of blades 120. For example, the turbine 110 includes a plurality of stages including rows of stationary blades 122 extending from the rotor wheel 118 and rows of rotating blades 120.

[0028] Compressor 124 is coupled downstream of intake section 123, and a plurality of combustors 126 are coupled circumferentially about rotor assembly 112 such that each combustor 126 is in flow communication with compressor 124. Exhaust section 130 is coupled downstream of turbine 110. Turbine 110 is rotatably coupled to compressor 124 via shaft 114.

[0029] During operation, air at atmospheric pressure is compressed by compressor 124 and delivered downstream to combustor 126. The air exiting the compressor is heated by adding fuel to the air and combusting the resulting air / fuel mixture. The airflow resulting from the combustion of the fuel in the combustion stage then expands through turbine 110, delivering some of its energy to drive turbine 110 and a load such as an electrical generator.

[0030] To generate the required drive torque, the turbine 110 includes one or more stages. Each stage includes a row of stationary blades 122 and a row of rotating blades 120 mounted on a rotor wheel 118. The stationary blades 122 direct the incoming gas from the combustion stage onto the rotating blades 120, thereby driving the rotor wheel 118 and the rotor shaft 114.

[0031] Figure 2 is an exemplary turbine blade 200 that may be used with a rotating machine (e.g., Figure 1 1 and 12. A front view of a blade 120 for use with a rotary machine 110 is shown in FIG. Additionally or alternatively, turbine blade 200 may be used with other electric turbines, including, but not limited to, gas turbofan aircraft engines, other aircraft engines, steam turbines, wind turbines, compressors, fans, and / or pumps. In an exemplary embodiment, each turbine blade 200 in a circumferential row of rotary machine 110 has substantially the same configuration as the other turbine blades in the row. In alternative embodiments, at least one turbine blade 200 in each row may be different from the remaining blades in the row.

[0032] The turbine blade 200 includes an airfoil portion or airfoil 202 including a leading edge 204 and an opposing trailing edge 206. A pressure sidewall 208 and a suction sidewall 210 each extend from the leading edge 204 to the trailing edge 206. The turbine blade 200 also includes a root 212 that enables the blade 200 to be mounted on a rotating machine (e.g., a rotating machine 110 (e.g., Figure 1 For example, the root 212 enables the turbine blade 200 to be coupled to the turbine rotor wheel 118 of the rotary machine 110. In the exemplary embodiment, the root 212 is in the form of a dovetail 212. The airfoil 202 and the root 212 are separated by a platform 214, which may include an "angel wing" seal (not shown).

[0033] The airfoil 202 extends between a platform 214 and a tip shroud 216 that is securely coupled to the radially outer end of the airfoil 202 opposite the platform 214. The pressure sidewall 208 is generally concave, and the suction sidewall 210 is generally convex. Thus, the airfoil 202 has an arcuate profile. The curvature of the pressure sidewall 208 and the suction sidewall 210 that define the arcuate profile of the airfoil 202 may vary depending on the particular turbine and stage in which the airfoil 202 is intended to be used. The present disclosure is not limited to any particular geometry of the airfoil 202, and the embodiments disclosed herein are suitable for use with airfoils 202 of various geometries.

[0034] The airfoil 202 also includes a pair of partial span shrouds 218 and 220 that help adjust and / or dampen the vibration characteristics of the airfoil 202 during operation. The partial span shrouds 218 and 220 extend outwardly away from the airfoil 202 in a mirrored relationship. More specifically, the shroud 218 extends outwardly from the airfoil pressure sidewall 208, and the shroud 220 extends outwardly from the airfoil suction sidewall 210. In an exemplary embodiment, the partial span shrouds 218 and 220 extend outwardly from the respective sidewalls 208 and 210 at the same radial span. The partial span shrouds 218 and 220 of the turbine blades 200 in each circumferential row at each stage of the rotary machine 110 may be substantially circumferentially aligned so that each of the shrouds 218 and 220 extends outwardly from the respective airfoil 202 at the same radial span position. Alternatively, the shrouds 218 and 220 may extend outwardly from the respective airfoil 202 at different radial spanwise locations. The partial span shrouds 218 and 220 may have the same size and shape, each extending an equal axial distance from the respective sidewalls 208 and 210, or alternatively, the shrouds 218 and 220 may be different in shape and / or size from each other.

[0035] As described above, the turbine blade 200 includes a tip shroud 216 attached to the radially outer end of the airfoil 202. Alternatively, the tip shroud 216 may be integral with the airfoil 202. The tip shroud 216 may generally define the radially outermost portion of the blade 200, and the tip shroud 216 provides a surface area that extends substantially perpendicular to the airfoil 202 so that it covers or covers the tip of the airfoil 202. During operation, the tip shroud 216 joins two adjacent tip shrouds 216 of adjacent blades 200 at opposite ends to form a generally annular ring or shroud that circumscribes the hot gas path at the location of the blade 200 stage. This "annular ring" keeps the expanding gas of the hot path on the airfoil 202 (i.e., it does not allow the gas to slip over the end of the airfoil blade), so that a greater proportion of the energy in the working fluid can be converted into mechanical energy by the turbine blades. Therefore, the tip shroud generally improves the performance of the gas turbine.

[0036] Figure 3 and Figure 4 The tip shroud 216 is shown in greater detail. As shown, the tip shroud 216 includes a seal rail 222 extending between a first end 224 and a second end 226 of the tip shroud. Alternative embodiments may include more seal rails 222 (e.g., two seal rails 222, three seal rails 222, etc.) or no seal rails 222 at all. As is understood in the art, the seal rail 222 may have any of a variety of cooling passages (not shown) extending therethrough to cool the tip shroud 216.

[0037] The tip shroud 216 also includes a radial outer surface 228 located in an XY plane containing the X-axis and the Y-axis. The sealing rail 222 extends radially outward from the radial outer surface 228 in the Z-axis direction. The radial outer surface 228 spans a leading edge portion 230 of the tip shroud 216 and a trailing edge portion 232 of the tip shroud 216. The periphery of the leading edge portion 230 is surrounded by a leading edge wall 234. The periphery of the trailing edge portion 232 is surrounded by a trailing edge wall 236. Each of the leading edge wall 234 and the trailing edge wall 236 extends downward from the radial outer surface 228. The leading edge portion 230 of the tip shroud 216 is firmly coupled to the leading edge 204 of the airfoil 202. The trailing edge portion 232 of the tip shroud 216 is firmly fixed to the trailing edge 206 of the airfoil 202.

[0038] like Figure 3 and Figure 4 As shown, the blade 200 also includes a hardface structure attached to the tip shroud 216. The hardface structures in the exemplary embodiment are pre-sintered preform structures 238 and 240, otherwise referred to herein as pre-sintered preforms 238 and 240, or PSPs 238 and PSPs 240. PSP 238 is coupled (e.g., brazed or welded) to a first end 224 of the tip shroud 216, and PSP 240 is coupled (e.g., brazed or welded) to a second end 226 of the tip shroud 216. Each PSP 238 and 240 functions as a wear part to help improve wear characteristics at the first end 224 and the second end 226 of the tip shroud 216, respectively, thereby helping to extend the useful life of the associated blade 200. In particular, the PSP 238 and PSP 240 attached to the respective ends 224 and 226 help protect the tip shroud 216 at these locations from wear caused by frictional contact during operation when the tip shroud 216 is exposed to centrifugal loads, pressure loads, thermal loads, and vibration loads. In some embodiments, each of the PSP 238 and PSP 240 is coupled to the first end 224 and the second end 226, respectively, by brazing.

[0039] The PSP 238 and the PSP 240 each have a suitable predetermined geometry when attached to the respective ends 224 and 226 of the tip shroud 216. For example, the PSP 238 and the PSP 240 have substantially the same geometry as the respective ends 224 and 226 and cover the sealing rail 222 at the respective ends 224 and 226. When attached, the PSP 238 and the PSP 240 each define an outer surface 242 and 244, respectively. The outer surfaces 242 and 244 extend substantially parallel to each other and are substantially perpendicular to the radial outer surface 228. Therefore, the outer surfaces 242 and 244 each lie in a ZY plane containing the Z axis and the Y axis. The PSP 238 and the PSP 240 also have a suitable thickness, which is measured as the distance extending between the respective outer surfaces 242 and 244 and the respective ends 224 and 226 to which the PSP 238 and the PSP 240 are attached in the X-axis direction.

[0040] The PSP 238 and PSP 240 may be machined after being attached to the respective ends 224 and 226 to ensure that the respective outer surfaces 242 and 244 are substantially planar and to remove excess material from the PSP 238 and PSP 240. Machining of the PSP 238 and PSP 240 may be performed using any now known or later developed machining process, such as, but not limited to, electrical discharge machining (EDM), wire EDM, grinding, laser cutting, etc. The machining tool (e.g., Figure 6 The machining tool 602 in the embodiment of the present invention is operably connected to a controller (e.g., Figure 6 Controller 610 in the communication device (e.g., Figure 6 The motion device may be a truss system, a computer numerical control (CNC) machine, a Cartesian robot, or other suitable system that facilitates multi-axis motion of a machining tool. A controller is used to control the multi-axis motion of the motion device to guide the tool path of the machining tool. As the description proceeds, the motion device may also be referred to as a CNC unit or a CNC system.

[0041] During operation, the PSP 238 and the PSP 240 may deteriorate or degrade due to exposure to loads (e.g., mechanical loads, vibration loads, and / or thermal loads). Repair of the blade 200 may include replacing one or both of the PSP 238 and / or the PSP 240 with a new PSP 238 and / or a new PSP 240. Generally, the initial PSP 238 and / or the PSP 240 are removed, and the new PSP 238 and / or the PSP 240 are attached (e.g., brazed or welded) to the respective ends 224 and 226 of the tip shroud 216. The new PSP 238 and / or the PSP 240 are then machined to a target profile (e.g., by planarizing the respective outer surfaces 242 and 244 and removing excess material).

[0042] During machining of the new PSP 238 and / or PSP 240, the motion of the motion device operably coupled to the machining tool is guided by the coordinate system. In particular, the target profile of the PSP 238 and / or PSP 240 is referenced to the X-axis, Y-axis, and Z-axis and converted to coordinate values ​​in the X, Y, and Z Cartesian coordinate system relative to the origin in the coordinate system. For example, the outer surface 242 and / or the outer surface 244 are machined according to the Z coordinate value and the Y coordinate value at the fixed X coordinate value relative to the origin. By defining the X, Y, and Z coordinate values ​​of the PSP 238 and / or PSP 240, the target profile of the PSP 238 and / or PSP 240 can be more accurately determined, and the motion device operably coupled to the machining tool can be guided accordingly.

[0043] Additional references Figure 5 , showing the manufacture (eg, repair) of a tip shield 216 (in Figure 3 and Figure 4 The turbine blade 200 (shown in Figure 2 Although the method 300 will be described in the context of repairing a turbine blade 200, it should be understood that the method 300 may be used for initial manufacturing of the turbine blade 200 (e.g., before the turbine blade 200 has been used with the turbine engine 110 during operation).

[0044] Method 300 may use system 600 ( Figure 6 ) is performed, the system includes a system operably coupled to a multi-axis computer numerical control (CNC) unit (e.g., Figure 6 CNC unit 604) of the machining tool (e.g., Figure 6602 in the machining tool 600). System 600 may be referred to herein as a CNC system. In various embodiments, machining tool 602 may be, for example, an electrical discharge machining (EDM) tool, a wire EDM tool, a grinding tool, a laser cutting tool, etc. CNC systems used with machining tools are known in the art and are described, for example, in U.S. Pat. No. 7,351,290 B2 (S. Rutkowski et al.), which is incorporated herein by reference in its entirety. A CNC unit (e.g., unit 604) facilitates movement of a machining tool (e.g., machining tool 602) along a plurality of X-, Y-, and Z-axes.

[0045] Will refer to Figure 6 The method 300 is described with reference to the system 600 shown, which includes a machining tool 602 operably coupled to a CNC unit 604. To begin the method 300, the turbine blade 200 is loaded onto the CNC unit 604, i.e., disposed within the CNC unit. For example, the turbine blade 200 may be loaded onto a workpiece holder 606 of the CNC unit 604. The turbine blade 200 loaded onto the workpiece holder is positioned at Figure 6 Schematically represented by a workpiece 608 located on a workpiece support 606 .

[0046] The CNC unit 604 is operable to move the machining tool 602 along one or more of the X-axis, the Y-axis, and the Z-axis relative to the workpiece 608. The workpiece support 606 is also operable to move the workpiece about or along one or more axes relative to the machining tool 602. A sensor 612 (e.g., a contact probe, a camera, or a tool sensor) is mounted within the system 600 (e.g., mounted on the CNC unit 604) to calibrate and / or position the machining tool 602 relative to the workpiece 608. One or more sensors 612 may be included and mounted in the system 600 to enable the system to operate as described herein.

[0047] In an exemplary embodiment, the system 600 includes a controller 610 that is communicatively coupled to a machining tool 602, a CNC unit 604, a workpiece support 606, and a sensor 612. The controller 610 can communicate with one or more of these components via a communication interface that is communicatively coupled to one or more of these devices. The communication interface can include, but is not limited to, a wired network adapter, a wireless network adapter, a mobile telecommunications adapter, a serial communication adapter, or a parallel communication adapter. The communication interface can receive data signals from or transmit data signals to one or more remote devices, such as a machining tool 602, a CNC unit 604, a workpiece support 606, and / or a sensor 612.

[0048] The controller 610 is operable to control components of the system 600 (e.g., machining tool 602, CNC unit 604, workpiece support 606, and sensor 612) by executing instructions stored in a memory device 616 via a processor 614, which is communicatively coupled to the processor 614. The processor 614 may include one or more processing units, such as, for example, a multi-core configuration. The memory device 616 is one or more devices that allow information such as executable instructions or other data to be stored and retrieved. The memory device 616 may include one or more computer-readable media, such as, but not limited to, random access memory (RAM), dynamic RAM, static RAM, solid state disk, hard disk, read-only memory (ROM), erasable programmable ROM, electrically erasable programmable ROM, or non-volatile RAM memory. The above memory types are exemplary only and are therefore not limited to the types of memory that can be used to store computer programs.

[0049] The processor 614 may be programmed by encoding operations as one or more executable instructions and providing these executable instructions in the memory device 616. In various embodiments, the processor 614 may be programmed to coordinate and control the movement of the CNC unit 604, the machining tool 602, and / or the workpiece support 606 in any one or a combination of the X-axis, the Y-axis, and the Z-axis. In this regard, the processor 614 may be programmed to control multi-axis movement of the machining tool 602 relative to the workpiece 608. The processor 614 may adjust the power settings of the machining tool 602, including, for example, by adjusting the amount of force (e.g., mechanical and / or electrical) applied by the machining tool 602 to the workpiece 608.

[0050] The memory device 616 may store data associated with the operation of the system 600, including, but not limited to, real-time and historical operating parameter values ​​or any other type of data. The memory device 616 may store instructions that can be executed by the processor 614 to control the CNC unit 604, the workpiece support 606, and / or the machining tool 602 based on, for example, the desired geometry of the workpiece 608. The desired geometry of the workpiece 608 may be defined by a three-dimensional drawing file (e.g., obtained from a CAD / CAM program) stored in the memory device 616. In some embodiments, the memory device 616 may include, but is not limited to, sufficient data, algorithms, and commands to enable the processor 614 to control the components of the system 600 to operate as described herein.

[0051] In some embodiments, the controller 610 includes a presentation interface 618 coupled to the processor 614. The presentation interface 618 presents information (such as a user interface) to an operator of the system 600. In one embodiment, the presentation interface 618 includes a display adapter (not shown) coupled to a display device (not shown), such as a cathode ray tube (CRT), a liquid crystal display (LCD), an organic LED (OLED) display, or an "electronic ink" display. In some embodiments, the presentation interface 618 includes one or more display devices. Additionally, or alternatively, the presentation interface 618 includes an audio output device (not shown), such as, but not limited to, an audio adapter, a speaker, or a printer (not shown).

[0052] In some embodiments, the controller 610 includes a user input interface 620. In an exemplary embodiment, the user input interface 620 is coupled to the processor 614 and receives input from an operator. The user input interface 612 may include, for example and without limitation, a keyboard, a pointing device, a mouse, a stylus, a touch-sensitive control pad (such as, but not limited to, a touch pad or a touch screen), and / or an audio input interface (such as, but not limited to, a microphone). A single component, such as a touch screen, may serve as both a display device for the presentation interface 618 and a user input interface 620.

[0053] The method 300 includes identifying or determining 302 an initial reference surface (first origin) for a controller 610 to control movement of a machining tool 602 (e.g., via a CNC unit 604). In order for the controller 610 to control movement of the machining tool 602 as accurately as possible, the controller must know the position of the machining tool very accurately. A sensor 612 may be used to determine a reference surface, which may then be processed by the controller 610 to control movement of the machining tool 602 via the CNC unit 604. For example, the sensor 612 used to determine the reference surface may be a contact probe. When contact with the probe occurs, the position of the machining tool 602 may be calibrated by such a probe by recording the position of the probe axis scale. Based on the observed deviation between the programmed position and the actual position, a compensation offset may be determined and stored in a memory device 616 of the controller 610. The offset compensates for the difference between the programmed contact position and the actual contact position of the machining tool 602.

[0054] In the exemplary method 300, determining 302 an initial reference surface includes probing an outer surface of the workpiece 608 at the area to be machined. For example, the sensor 612 may be used to probe an outer surface of a PSP of the turbine blade 200 (e.g., the outer surface 242 of the PSP 238 or the outer surface 244 of the PSP 240) that will be removed and replaced during repair of the turbine blade. The probed surface is set as an origin to calibrate the position of the machining tool 602 by the controller 610 (and if applicable, a predetermined offset may also be applied at this stage).

[0055] The method 300 also includes identifying or determining 304 a reference surface on the workpiece 608. For example, the reference surface can be defined in the tip shroud 216. The reference surface can be formed (e.g., machined) in the tip shroud 216 prior to starting the method, or the reference surface can be formed during the method 300 (e.g., machined using the machining tool 602). The reference surface can be identified or determined 304 using a sensor 612 (e.g., by probing the reference surface), and this information can be processed by a controller 610 for use in controlling the machining tool 602.

[0056] In exemplary method 300, a reference surface is formed in tip shroud 216 and is oriented substantially parallel to an outer surface of a PSP (eg, PSP 238 or PSP 240) detected when determining 302 a reference surface. Figure 3 and Figure 4 In the exemplary embodiment, the reference surface is a notch 246 formed in the leading edge wall 234. The notch 246 defines a surface oriented substantially parallel to the outer surface 244 of the PSP 240. The outer surface 244 of the PSP 240 serves as the initial reference surface previously detected when determining 302 the reference surface.

[0057] Determining 304 the reference surface also includes determining a distance D1 between the notch 246 and the outer surface 244 of the PSP 240 measured along the X-axis direction. The distance D1 can be used by the controller 610 to control the machining tool 602 in subsequent machining, as described below. The distance D1 can be, for example, between about 3 inches and about 5 inches, or such as between about 4.0 inches and about 4.2 inches. The distance D1 can vary depending on the part repaired by the process 300 and the relative size of the part. The notch 246 oriented substantially parallel to the outer surface 244 and the distance D1 determined between the notch 246 and the outer surface 244 ensure that the spatial relationship between the notch 246 and the new PSP 240 is easily determined by the controller 610 for controlling the machining tool 602 to machine the new PSP 240 to a target profile, as described below. It should be appreciated that in alternative embodiments, exterior surface 242 of PSP 238 may be detected as an initial reference surface when determining 302 a reference surface, and a notch (not shown) may be formed in trailing edge wall 236 and subsequently determined 304 as a datum surface.

[0058] In some embodiments, determining 304 the reference surface includes machining the reference surface (e.g., the recess 246) in the tip shroud 216 after determining 302 the initial reference surface. The reference surface may be machined to a predetermined or predefined distance D1 from the reference surface determined 302. For example, after determining 302 the reference surface, the machining tool 602 may be controlled via the controller 610 and the CNC unit 604 to machine the reference surface (e.g., the recess 246) in the tip shroud 216 to a distance D1 from the initial reference surface (e.g., the outer surface 244 of the PSP 240). Alternatively, the reference surface may be machined in the tip shroud 216 and the distance D1 between the reference surface (e.g., the recess 246) and the initial reference surface (e.g., the outer surface 244) may be subsequently determined (e.g., by probing the reference surface and measuring the distance D1).

[0059] The method 300 continues by removing 306 the PSP from the tip shroud, the PSP defining the outer surface previously detected when determining 302 the reference surface. The PSP may be removed 306 from the tip shroud using a machining tool 602 or by another suitable device. In the exemplary method 300, the PSP 240 defining the outer surface 244 previously detected when determining 302 the reference surface is removed 306. In some examples, the PSP 238 defining the outer surface 242 may also be removed 306. Because the outer surface 242 of the PSP 238 is located at a known or predetermined distance D2 from the outer surface 244 of the PSP 238 as measured in the direction of the X-axis, and because the outer surfaces 242 and 244 are oriented to be substantially parallel to each other, additional detection of the outer surface 242 is not required prior to removing the PSP 240 because the spatial relationship between the outer surfaces 242 and 244 is known (e.g., stored in the memory device 616). For example, the distance D2 may be defined by a three-dimensional drawing file stored in the memory device 616. After removing 306 the PSP 240 , and optionally the PSP 238 , a new PSP 240 is attached 308 (eg, brazed or welded) to the second end 226 of the tip shroud 216 , and optionally a new PSP 238 is attached 308 (eg, brazed or welded) to the first end 224 of the tip shroud 216 .

[0060] The method 300 continues by machining 310 the new PSP 240 attached 308 to the tip shroud 216 to a target profile using a machining tool 602 operably coupled to a controller 610. The target profile is converted to coordinate values ​​that are readily determined by the controller 610 by reference to a reference surface (e.g., the notch 246) in the tip shroud 216. Specifically, the target profile of the attached 308 PSP 240 substantially matches the target profile of the previously removed 306 PSP 240. As described above, the target profile is converted to coordinate values ​​that are readily determined by the controller 610 using the reference surface (e.g., the notch 246) as an origin (reference point) for machining 310. For example, after the PSP 240 is attached 308 and machined 310, the PSP 240 defines an outer surface 244 that substantially matches the outer surface 244 defined by the previously removed 306 PSP 240. That is, when attached 310, the outer surface 244 of the PSP 240 is oriented substantially parallel to the reference surface (e.g., notch 246) and is located at a precise distance D1 from the reference surface. In this regard, by detecting (e.g., using sensor 612) the reference surface (e.g., notch 246) and using the reference surface as an origin during machining 310, the target profile (e.g., planarization of the outer surface 244) of the previously attached 308 PSP 240 can be easily determined. The new PSP 238 (where previously attached 308) can be machined 312 using the distance D2 measured between the outer surface 242 of the previously removed 306 PSP 238 and the outer surface 244 of the PSP 240, respectively. A blend-to-finish operation is then performed on the previously attached 310 PSP 240 and optionally the attached 312 PSP 238 to smooth these newly added components and obtain a finished tip shroud 216 for subsequent operation of the rotary machine 110 .

[0061] The above-described embodiments present several advantages over conventional methods for repairing turbine blades having tip shrouds that include one or more PSP structures. For example, in conventional methods, portions of the blade (e.g., partial span shrouds) may be used as reference points for machining a PSP attached to the tip shroud. These reference points are located at different locations from the tip shroud, and the coordinate system used to guide the machining tool must be transformed based on the rotation and / or translation of the tip shroud relative to the partial span shroud. These methods also require data storage so that the coordinate system can be transformed based on these reference points once a new PSP is attached to the tip shroud. These conventional methods are limited by reliance on reference points that are not located on the portion of the component to which the PSP is applied, translational and rotational motions derived from coordinate system transformations that need to reach the same position during initial machining and final machining, and data storage. Errors in machining hardface PSPs may be amplified due to indirect positioning, multiple probing, transformations, and data storage.

[0062] The above-described embodiments overcome the limitations and disadvantages of these conventional methods by forming a reference surface in the tip shroud that is located at a known or fixed distance from a new PSP attached to the tip shroud during manufacturing and / or repair. The reference surface is used as an origin when determining coordinate values ​​for subsequent machining of the new PSP (e.g., by forming an outer surface oriented parallel to the reference surface and located at a known or fixed distance from the reference surface). Advantages of this embodiment include reducing or eliminating data storage from the machining process, and reducing detection and coordinate system transformations from different locations on the turbine blade. These are achieved by using a fixed distance origin measured at the level of the tip shroud (e.g., using a reference plane with a Z-axis coordinate at the level of the Z-axis coordinate of the new PSP). In addition, since the embodiments described herein use plane-to-plane measurements, coordinate measuring machines (CMMs) and hardness testers can be relied upon for in-process inspection.

[0063] Other aspects of the disclosure are provided by the subject matter of the following clauses:

[0064] Item 1. A method for repairing a turbine blade, the turbine blade comprising 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 comprising a machining tool; determining a first distance between a surface of the first PSP and a reference surface formed in the tip shroud; removing the first PSP from the tip shroud; connecting a second PSP to the tip shroud; and machining the surface of the second PSP using the machining tool, wherein machining the second PSP surface comprises using the reference surface as a reference to control movement of the machining tool so that the machined second PSP surface is located at the first distance from the reference surface.

[0065] Clause 2. The method of clause 1, further comprising machining the reference surface in the tip shroud using the machining tool such that the reference surface is located at the first distance from the first PSP surface.

[0066] Clause 3. The method of any of the preceding clauses, wherein determining the first distance comprises machining the reference surface in the tip shroud and measuring a distance between the reference surface and the first PSP surface.

[0067] Clause 4. The method of any of the preceding clauses, wherein determining the first distance comprises determining a predefined first distance and machining the reference surface in the tip shroud to be the predefined first distance from the first PSP surface.

[0068] Clause 5. The method of any of the preceding clauses, wherein coupling the second PSP to the tip shroud comprises securely coupling the second PSP and the tip shroud together by one of brazing and welding.

[0069] Clause 6. A method according to any of the preceding clauses, further comprising connecting a third PSP to the tip shroud and, after machining the second PSP surface, machining the surface of the third PSP to a second distance measured between the machined second PSP surface and the machined third PSP surface.

[0070] Clause 7. The method of any of the preceding clauses, wherein machining the third PSP surface to the second distance comprises machining the third PSP surface to a predefined second distance measured between the machined second PSP surface and the machined third PSP surface.

[0071] Item 8. A method for repairing a turbine component comprising a first hardface structure and a second hardface structure, the method comprising: positioning the turbine blade within a system comprising a machining tool; determining a first distance between a surface of the first hardface structure and a reference surface formed in the turbine component; removing the first hardface structure and the second hardface structure from the turbine component; coupling a third hardface structure to the turbine component and coupling a fourth hardface structure to the turbine component; machining the surface of the third hardface structure using the machining tool, wherein machining the surface of the third hardface structure comprises using the reference surface as a reference to control movement of the machining tool so that the machined surface of the third hardface structure is located at a first distance from the reference surface; and machining the surface of the fourth hardface structure using the machining tool to a second distance measured between the machined surface of the third hardface structure and the machined surface of the fourth hardface structure.

[0072] Clause 9. A method according to any of the preceding clauses, wherein machining the fourth hardface structural surface comprises machining the fourth hardface structural surface to the second distance, the second distance being substantially equal to the distance measured between the first hardface structural surface and the second hardface structural surface.

[0073] Clause 10. A method according to any of the preceding clauses, wherein machining the fourth hardface structural surface to the second distance comprises machining the fourth hardface structural surface to a predefined second distance measured between the machined third hardface structural surface and the machined fourth hardface structural surface.

[0074] Clause 11. A method according to any of the preceding clauses, the method further comprising machining the reference surface in the turbine component using the machining tool, wherein machining the reference surface in the turbine component comprises using the first hard surface structural surface as a reference to control movement of the machining tool.

[0075] Clause 12. The method of any of the preceding clauses, wherein determining the first distance comprises machining the reference surface in the turbine component and measuring a distance between the reference surface and the first hardfacing structural surface.

[0076] Clause 13. The method of any of the preceding clauses, wherein determining the first distance comprises determining a predefined first distance and machining the reference surface in the turbine component to be the predefined first distance from the first hardface structural surface.

[0077] Clause 14. The method of any of the preceding clauses, wherein coupling the first and second hardface structures to the turbine component comprises securely coupling each of the first and second hardface structures to the turbine component by one of brazing and welding.

[0078] Item 15. A method for repairing a turbine blade, the turbine blade comprising 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 in a system comprising a machining tool; controlling the machining tool to machine a reference surface in the tip shroud; removing the first PSP and the second PSP from the tip shroud; connecting a third PSP and a fourth PSP to the tip shroud; controlling the machining tool to machine the third PSP using the reference surface as a reference; and after machining the third PSP, controlling the machining tool to machine the fourth PSP.

[0079] Clause 16. The method of any of the preceding clauses, wherein controlling the machining tool to machine the reference surface comprises controlling the machining tool to machine the reference surface using a surface of the first PSP as a reference.

[0080] Clause 17. The method of any of the preceding clauses, wherein controlling the machining tool to machine the reference surface comprises controlling the machining tool to machine the reference surface a first distance from the first PSP surface.

[0081] Clause 18. The method of any of the preceding clauses, wherein controlling the machining tool to machine the third PSP comprises controlling the machining tool to machine the third PSP using the reference surface as a reference and based on the first distance.

[0082] Clause 19. The method of any of the preceding clauses, 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 reference surface.

[0083] Clause 20. The method of any of the preceding clauses, 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 PSP and the second PSP.

[0084] Exemplary embodiments of turbine blades and methods of manufacturing and repairing turbine blades are described in detail above. The present disclosure is not limited to the specific embodiments described herein, but the components of the system can be used independently and separately from other components described herein. For example, the methods disclosed herein can be used in conjunction with rotating components other than those specifically described herein, and the turbine blades can also be used in conjunction with other rotating machines and methods, and are not limited to practice only with gas turbine engines or steam turbine engine components as described herein. Instead, the exemplary embodiments can be implemented and used in conjunction with many other rotating machinery applications.

[0085] Although specific features of various embodiments of the present invention may be shown in some drawings and not in others, this is for convenience only. In addition, reference to "one embodiment" in the above description is not intended to be interpreted as excluding the existence of additional embodiments that also include the described features. In accordance with the principles of the present invention, any feature of a drawing may be referenced and / or claimed in conjunction with any feature of any other drawing.

[0086] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any device or system and performing any combined method. The patentable scope of the invention is defined by the claims, and may include other examples that occur to one skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. A method of repairing a turbine blade, the turbine blade comprising 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 reference surface formed in the tip shroud; removing the first PSP from the tip shroud; coupling a second PSP to the tip shroud; as well as The surface of the second PSP is machined using the machining tool, wherein machining the second PSP surface includes controlling movement of the machining tool using the reference surface as a reference so that the machined second PSP surface is located at the first distance from the reference surface. 2 . The method of claim 1 , further comprising machining the reference surface in the tip shroud using the machining tool so that the reference surface is located at the first distance from the first PSP surface. 3 . The method of claim 1 , wherein determining the first distance comprises machining the reference surface in the tip shroud and measuring a distance between the reference surface and the first PSP surface.

4. The method of claim 1, wherein determining the first distance comprises determining a predefined first distance and machining the reference surface in the tip shroud to be the predefined first distance from the first PSP surface. 5 . The method of claim 1 , wherein coupling the second PSP to the tip shroud comprises securely coupling the second PSP and the tip shroud 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 predefined second distance measured between the machined second PSP surface and the machined third PSP surface.

8. A method of repairing a turbine component comprising a first hardface structure and a second hardface structure, the method comprising: positioning the turbine component within a system including a machining tool; determining a first distance between a surface of the first hardface structure and a reference surface formed in the turbine component; removing the first hardface structure and the second hardface structure from the turbine component; coupling a third hardface structure to the turbine component and coupling a fourth hardface structure to the turbine component; machining a surface of the third hardface structure using the machining tool, wherein machining the surface of the third hardface structure includes controlling movement of the machining tool using the reference surface as a reference so that the machined surface of the third hardface structure is located at the first distance from the reference surface; as well as The surface of the fourth hardface structure is machined using the machining tool to a second distance measured between the machined third hardface structure surface and the machined fourth hardface structure surface.

9. The method of claim 8, wherein machining the fourth hardface structural surface comprises machining the fourth hardface structural surface to the second distance, the second distance being substantially equal to the distance measured between the first hardface structural surface and the second hardface structural surface.

10. The method of claim 8, wherein machining the fourth hardface structural surface to the second distance comprises machining the fourth hardface structural surface to a predefined second distance measured between the machined third hardface structural surface and the machined fourth hardface structural surface.

11. The method of claim 8, further comprising machining the reference surface in the turbine component using the machining tool, wherein machining the reference surface in the turbine component comprises controlling movement of the machining tool using the first hardface structural surface as a reference. 12 . The method of claim 8 , wherein determining the first distance comprises machining the reference surface in the turbine component and measuring a distance between the reference surface and the first hardfacing structural surface.

13. The method of claim 8, wherein determining the first distance comprises determining a predefined first distance and machining the reference surface in the turbine component to be the predefined first distance from the first hardface structural surface.

14. The method of claim 8, wherein coupling the first and second hardface structures to the turbine component comprises fixedly coupling each of the first and second hardface structures to the turbine component by one of brazing and welding.

15. A method of repairing a turbine blade, the turbine blade comprising 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 reference surface in the tip shroud; removing the first PSP and the second PSP 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 reference surface as a reference; as well as After machining the third PSP, the machining tool is controlled to machine the fourth PSP. 16 . The method of claim 15 , wherein controlling the machining tool to machine the reference surface comprises controlling the machining tool to machine the reference 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 reference surface comprises controlling the machining tool to machine the reference 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 reference 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 reference 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 PSP and the second PSP.

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