Patent Description:
Typical aircraft propulsion systems include one or more gas turbine engines, which each generally include a turbomachine. The turbomachine includes, in serial flow order, a compressor section, a combustion section, a turbine section, and an exhaust section. In operation, air is provided to an inlet of the compressor section where one or more axial compressors progressively compress the air until it reaches the combustion section. Fuel is mixed with the compressed air and burned within the combustion section to provide combustion gases. The combustion gases are routed from the combustion section to the turbine section. The flow of combustion gases through the turbine section drives the turbine section and is then routed through the exhaust section, e.g., to atmosphere.

<CIT> relates to solid state resistance welding for airfoil repair, wherein copper braiding may be used as a welding shunt. <CIT> relates to a method for friction-welding a blade to a turbomachine including a surfacing process.

In a first aspect of the invention, a method of repairing an airfoil is defined, according to claim <NUM>.

In a second aspect of the invention, an electrode assembly is defined, according to claim <NUM>.

Reference will now be made in detail to present embodiments of the disclosure, one or more examples of which are illustrated in the accompanying drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the disclosure.

As used herein, the terms "first," "second," and "third" may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

The terms "forward" and "aft" refer to relative positions within a gas turbine engine or vehicle and refer to the normal operational attitude of the gas turbine engine or vehicle.

The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

The approximating language may refer to being within a +/- <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent margin in either individual values, range(s) of values, and/or endpoints defining range(s) of values.

A typical compressor has multiple stages or rows of rotor blades and corresponding stator vanes that sequentially increase the pressure of the air as it flows in an axial downstream direction. In some compressors, the compressor blades include dovetails for being removably mounted in a corresponding dovetail slot in the perimeter of a rotor disk. The dovetail-to-dovetail slot configuration permits the individual manufacture of each blade, and the individual replacement thereof in the event of blade damage during operation. However, it can be expensive to completely replace damaged blades, particularly when the damage is located near the tip of the blade such that a majority of the blade and the dovetail remains intact and undamaged.

In other compressors, the compressor blades may be provided as a bladed disk, also referred to as a blisk. A blisk includes a row of rotor airfoils integrally formed with the perimeter of a rotor disk in a one-piece or unitary configuration. As such, unlike the removably mounted blades described above, in the event of a damaged blisk airfoil, either the entire blisk must be replaced or the damaged airfoil must be removed and replaced without damaging adjacent airfoils, which could be expensive and/or complicated. Other airfoils within a turbomachine, for example in the fan and turbine section, also may have either a dovetail configuration or be part of a blisk and face similar drawbacks or limitations as described above.

Accordingly, improved airfoil repair and airfoil handling methods and apparatus would be desirable.

Generally, the present subject matter provides methods and apparatus for airfoil repairs. For instance, the present subject matter provides methods and apparatus for removing a damaged portion of an airfoil to form a cropped airfoil and joining an airfoil repair component to the cropped airfoil to repair the airfoil. Such airfoil repairs can be time-consuming and/or expensive, while often also having low yield rates, but the methods and apparatus described herein can improve success and yield while reducing repair time and costs for repair of individual airfoils, e.g., airfoils secured to a disk via a dovetail, and/or integral airfoils, e.g., blisk airfoils that are integrally formed with a disk. For example, an airfoil repair component includes a repair attachment section for attaching the airfoil repair component to the cropped airfoil at a cropped airfoil attachment section. In at least some embodiments, the repair attachment section is oversized with respect to the cropped airfoil attachment section such that the repair attachment section has a repair chord length longer than a cropped chord length of the cropped airfoil attachment section and a repair width wider than a cropped width of the cropped airfoil attachment section. A locally or wholly oversized airfoil repair component can improve the chances of proper alignment between the airfoil repair component and the cropped airfoil (i.e., an airfoil with a damaged portion removed), with increased material margin or stock for post-joining processing to achieve the net shape of the original airfoil. Further, the present subject matter provides an electrode assembly comprising a repair component electrode and a cropped airfoil electrode, which surround the airfoil repair component and the cropped airfoil, respectively, and are positioned to align the airfoil repair component with the cropped airfoil such that when a current is passed therethrough under an applied force, the airfoil repair component is attached to the cropped airfoil. For instance, the present subject matter provides methods and apparatus for securing the airfoil repair component and/or the cropped airfoil within an electrode to eliminate over constraint and permit more accurate positioning of the airfoil repair component and/or cropped airfoil, while also reducing or eliminating hand tools in loading and unloading components from their respective electrodes, e.g., by using spring loaded design features and other easily hand-manipulated design features. Moreover, the present subject matter provides features for process feedback, environmental shielding, and/or stabilization that can produce higher quality welds or joints between the airfoil repair component and the cropped airfoil, better and/or faster alignment of the airfoil repair component with respect to the cropped airfoil, and/or easier post-joining extraction of the repaired airfoil.

Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures, <FIG> is a schematic view of an airfoil <NUM>, e.g., an airfoil of a gas turbine engine. <FIG> is a schematic view of a bladed disk <NUM>, also known as a blisk, having a plurality of airfoils <NUM> integrally formed with a rotor disk, such as may be used in a gas turbine engine. In at least some embodiments, the gas turbine engine may be a turbofan jet engine including a fan section and a core turbine engine disposed downstream from the fan section. The core turbine engine generally includes a substantially tubular outer casing that encases, in serial flow relationship, a compressor section including a booster or low pressure (LP) compressor and a high pressure (HP) compressor; a combustion section; a turbine section including a high pressure (HP) turbine and a low pressure (LP) turbine; and a jet exhaust nozzle section. A high pressure (HP) shaft or spool drivingly connects the HP turbine to the HP compressor. A low pressure (LP) shaft or spool drivingly connects the LP turbine to the LP compressor. During operation of the turbofan jet engine, a volume of air passes across fan blades of a fan disposed in the fan section. A first portion of the air is directed or routed into a bypass airflow passage and a second portion of the air is directed or routed into the LP compressor. The ratio between the first portion of air and the second portion of air is commonly known as a bypass ratio.

The pressure of the second portion of air is increased as it is routed through the high pressure (HP) compressor and into the combustion section, where it is mixed with fuel and burned to provide combustion gases. The combustion gases are routed through the HP turbine where a portion of thermal and/or kinetic energy from the combustion gases is extracted via sequential stages of HP turbine stator vanes that are coupled to the outer casing of the core turbine engine and HP turbine rotor blades that are coupled to the HP shaft or spool, thus causing the HP shaft or spool to rotate, thereby supporting operation of the HP compressor. The combustion gases are then routed through the LP turbine, where a second portion of thermal and kinetic energy is extracted from the combustion gases via sequential stages of LP turbine stator vanes that are coupled to the outer casing of the core turbine engine and LP turbine rotor blades that are coupled to the LP shaft or spool, thus causing the LP shaft or spool to rotate, thereby supporting operation of the LP compressor and/or rotation of the fan. The combustion gases are subsequently routed through the jet exhaust nozzle section of the core turbine engine to provide propulsive thrust.

Simultaneously, the pressure of the first portion of air is substantially increased as the first portion of air is routed through the bypass airflow passage before it is exhausted from a fan nozzle exhaust section, also providing propulsive thrust. The HP turbine, the LP turbine, and the jet exhaust nozzle section at least partially define a hot gas path for routing the combustion gases through the core turbine engine.

In some embodiments, the airfoil <NUM> depicted in <FIG> and <FIG> may be a compressor blade, such as a rotor blade of the LP compressor or the HP compressor of the turbofan jet engine described above. In other embodiments, the airfoil <NUM> depicted in <FIG> and <FIG> may be a turbine blade, such as a rotor blade of the LP turbine or the HP turbine of the turbofan jet engine. In still other embodiments, the airfoil <NUM> may be another airfoil of the turbofan jet engine described above, of another gas turbine engine, or of another assembly or system having one or more airfoils.

As shown in the depicted embodiments of <FIG> and <FIG>, the airfoil <NUM> includes a concave pressure side <NUM> opposite a convex suction side <NUM>. Opposite pressure side <NUM> and suction side <NUM> of the airfoil <NUM> extend radially along a span S from a root <NUM> to a tip <NUM> at the radially outermost portion of the airfoil <NUM>. That is, the root <NUM> defines a first radial extremity of the airfoil <NUM>, and the tip <NUM> defines a second radial extremity of the airfoil <NUM>, with the root <NUM> and the tip <NUM> spaced apart along a radial direction R. The pressure side <NUM> and the suction side <NUM> of the airfoil <NUM> extend axially along a chord length c between a leading edge <NUM> and an opposite trailing edge <NUM>. The leading edge <NUM> defines a forward end of the airfoil <NUM>, and the trailing edge <NUM> defines an aft end of the airfoil <NUM>, with the leading edge <NUM> and the trailing edge <NUM> spaced apart along an axial direction A. Further, the pressure side <NUM> defines an outer pressure surface <NUM> of the airfoil <NUM>, and the suction side <NUM> defines an outer suction surface <NUM> of the airfoil <NUM>.

More generally, the airfoil <NUM> may be described as having a first side opposite a second side, with either of the first side and the second side being the pressure side <NUM> or the suction side <NUM> and the other of the first and second sides being the other of the pressure side <NUM> and the suction side <NUM>. Each of the first side and the second side extend axially between a first edge and an opposite second edge, with either of the first edge and the second edge being the leading edge <NUM> or the trailing edge <NUM> and the other of the first and second edges being the other of the leading edge <NUM> and the trailing edge <NUM>. Further, the first side defines a first outer surface of the airfoil <NUM>, and the second side defines a second outer surface of the airfoil <NUM>, with either of the first outer surface and the second outer surface being the outer pressure surface <NUM> or the outer suction surface <NUM> and the other of the first and second outer surfaces being the other of the outer pressure surface <NUM> and the outer suction surface <NUM>.

In the embodiment of <FIG>, the airfoil <NUM> extends radially outward from a platform <NUM>. A dovetail <NUM> extends from the platform <NUM> in a radially opposite direction from the airfoil <NUM>. The dovetail <NUM> is configured to be received within a complementarily shaped dovetail slot in a rotor disk (not shown). In the depicted embodiment, the airfoil <NUM>, the platform <NUM>, and the dovetail <NUM> are secured to one another, or integrally formed as a single piece or component, such that the airfoil <NUM>, platform <NUM>, and dovetail <NUM> together are removably received in the rotor disk. It will be appreciated that a plurality of airfoils <NUM> are secured to the rotor disk via a corresponding number of dovetails <NUM> to form a stage of rotor blades, e.g., a stage of compressor blades of a gas turbine engine compressor. The plurality of airfoils <NUM> are circumferentially spaced apart from one another, or spaced apart along a circumferential direction C, to define a ring of airfoils <NUM>, similar to the airfoils <NUM> of the blisk <NUM> shown in <FIG>.

As further illustrated in <FIG>, a fillet <NUM> defines a transition between the pressure side <NUM> and the platform <NUM>, as well as the suction side <NUM> and the platform <NUM>. Moreover, the airfoil <NUM> defines a section line SL, e.g., at one half of the distance between the tip <NUM> at the leading edge <NUM>, and a leading edge fillet tangency taken at the fillet <NUM> between the leading edge <NUM> and the platform <NUM>.

As previously stated, <FIG> depicts a bladed disk or blisk <NUM> that has multiple airfoils <NUM> extending from a rotor disk <NUM> at an integral platform <NUM>. It will be appreciated that the airfoils <NUM> of the blisk <NUM> are configured as described with respect to <FIG>. However, rather than a separate platform <NUM> and dovetail <NUM> for each airfoil <NUM> as in the embodiment of <FIG>, the blisk <NUM> comprises a single platform <NUM> that serves as a platform for each of the multiple airfoils <NUM>. Further, no dovetails <NUM> are necessary in the embodiment of <FIG> because the airfoils <NUM> are integrally formed with the rotor disk <NUM>. As such, while the airfoils <NUM> of <FIG> are removable from the described rotor disk, the airfoils <NUM> of <FIG> are not removable with respect to the rotor disk <NUM> but, instead, are integrally formed with the platform <NUM> and rotor disk <NUM> to form the blisk <NUM>.

From time to time, an airfoil <NUM> may become damaged during use. For instance, the airfoil <NUM> may experience localized damage during service, e.g., through inadvertent tip rub against a shroud or casing, impingement by a foreign object, and/or other contact between the airfoil <NUM> and another component, object, or substance. The airfoil <NUM> may develop a damaged area <NUM>, such as illustrated on an airfoil <NUM> of the blisk <NUM> shown in <FIG>, which may be, e.g., a cavity. As used herein, the term "cavity" refers to any hollow space within the airfoil <NUM>, such as an opening, crack, gap, aperture, hole, etc. Such a cavity or damaged area <NUM> can be formed on or in the airfoil <NUM> through normal use and generally represents an area where fragments, chunks, pieces, etc. of the original airfoil material have broken off or been liberated from the airfoil <NUM>.

In at least some instances, the damaged area <NUM> hinders the functionality of the airfoil <NUM> such that the airfoil <NUM> should be repaired. Generally, the airfoil <NUM> could be repaired by replacing the entire airfoil <NUM> or through removal and replacement of a portion <NUM> of the airfoil <NUM> containing the damaged area <NUM>, which is referred to herein as the damaged portion <NUM>. In some embodiments, the damaged portion <NUM> may be removed along a plane below or radially inward with respect to the section line SL (<FIG>), such that more than half of the airfoil <NUM> is removed. In other embodiments, the damaged portion <NUM> may be removed along a plane above or radially outward with respect to the section line SL, such that less than half of the airfoil <NUM> is removed.

It will be appreciated that replacement of the entire airfoil <NUM> generally is more expensive than replacing only the damaged portion <NUM> of the airfoil <NUM>. Further, at least for the blisk <NUM>, replacing the entire airfoil <NUM> generally involves a complicated manufacturing process and could risk damaging the platform <NUM> and/or rotor disk <NUM> of the blisk <NUM>, as well as adjacent, undamaged airfoils <NUM>. Other complications of replacing the entire airfoil <NUM> may be realized as well.

Accordingly, to minimize replacement costs and manage complexity, the present subject matter provides methods, components, systems, and apparatus for replacing only the damaged portion <NUM>. For example, turning to <FIG>, and <FIG>, an airfoil component or airfoil repair component <NUM> to replace the damaged portion <NUM> is provided. As described in greater detail herein, the damaged portion <NUM> is removed from the airfoil <NUM> (e.g., above, below, or at the section line SL shown in <FIG>) to form a cropped airfoil <NUM>, such that the cropped airfoil <NUM> has a radial height less than the span S of the airfoil <NUM> (<FIG>). The cropped airfoil <NUM> comprises the airfoil root <NUM> and, thus, remains secured (or can be re-secured) to the platform <NUM> and dovetail <NUM> of the individual airfoils <NUM> described with respect to <FIG>, or remains integral with the rotor disk <NUM> and platform <NUM> of the blisk <NUM> of <FIG>. Further, the cropped airfoil <NUM> comprises the remaining portions of the pressure side <NUM>, suction side <NUM>, leading edge <NUM>, and trailing edge <NUM>, which are referred to herein as the cropped pressure side 102c, the cropped suction side 104c (<FIG>), the cropped leading edge 110c (<FIG>), and the cropped trailing edge 112c (<FIG>).

Like the airfoil <NUM>, the cropped airfoil <NUM> may have features that more generally be described as a cropped first side and an opposite cropped second side, which are either of the cropped pressure side 102c or the cropped suction side 104c. Each of the cropped first side and the cropped second side extend axially between a cropped first edge and an opposite cropped second edge, which are either of the cropped leading edge 110c or the cropped trailing edge 112c.

Referring to <FIG>, because the airfoil repair component <NUM> attaches to the cropped airfoil <NUM> to yield a repaired airfoil <NUM>, the airfoil repair component <NUM> is configured similar to the airfoil <NUM> described with respect to <FIG> and <FIG>. More particularly, referring to <FIG>, and <FIG>, the airfoil repair component <NUM> comprises a body <NUM> having a repair pressure side <NUM> opposite a repair suction side <NUM>, and a repair leading edge <NUM> opposite a repair trailing edge <NUM>. Further, the repair pressure side <NUM> and the repair suction side <NUM> extend axially between the repair leading edge <NUM> and the repair trailing edge <NUM>. More generally, the airfoil repair component <NUM> comprises a body <NUM> having a first side opposite a second side, with the first and second sides being either of the repair pressure side <NUM> and the repair suction side <NUM>, and the first and second sides extend axially between a first edge and a second edge, with the first and second edges being either of the repair leading edge <NUM> and the repair trailing edge <NUM>. Like the cropped airfoil <NUM>, the airfoil repair component <NUM> has a radial height that is less than the span S of the airfoil <NUM> (<FIG>).

The body <NUM> of the airfoil repair component <NUM> defines a repair attachment section <NUM> for attaching the airfoil repair component <NUM> to the cropped airfoil <NUM>. As shown in <FIG>, and <FIG>, the cropped airfoil <NUM> comprises a cropped airfoil attachment section <NUM>, which is the radially outermost section of the cropped airfoil <NUM>. Likewise, as depicted in <FIG>, and <FIG>, the repair attachment section <NUM> is the radially innermost section of the airfoil repair component <NUM>.

To attach the airfoil repair component <NUM> to the cropped airfoil <NUM>, the repair attachment section <NUM> is aligned with the cropped airfoil attachment section <NUM> and the airfoil repair component <NUM> is secured to the cropped airfoil <NUM>, e.g., by welding the airfoil repair component <NUM> to the cropped airfoil <NUM> as described in greater detail below. For instance, the repair attachment section <NUM> defines a repair joining face <NUM> (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>) and the cropped airfoil attachment section <NUM> defines a cropped joining face <NUM> (<FIG>), and the repair joining face <NUM> interfaces with the cropped joining face <NUM> as the airfoil repair component <NUM> is aligned with the cropped airfoil <NUM>. Then, the airfoil repair component <NUM> may be joined to the cropped airfoil <NUM>, e.g., along the interface between the repair joining face <NUM> and the cropped joining face <NUM>, through a welding or other appropriate joining process. It will be appreciated that the repair joining face <NUM> defines an inner end of the airfoil repair component <NUM> and an opposite tip <NUM> (<FIG>, <FIG>) defines an outer end of the airfoil repair component <NUM>, while the cropped joining face <NUM> defines an outer end of the cropped airfoil <NUM> and the opposite root <NUM> defines an inner end of the cropped airfoil <NUM>.

As illustrated in <FIG>, at least the repair attachment section <NUM> is oversized with respect to the cropped airfoil attachment section <NUM>. For example, the repair attachment section <NUM> has a repair chord length cr longer than a cropped chord length cc of the cropped airfoil attachment section <NUM>, i.e., the repair chord length longer cr than a cropped chord length cc of the cropped airfoil attachment section <NUM>. As another example, the repair attachment section <NUM> is oversized with respect to the cropped airfoil attachment section <NUM> such that a repair width wr of the body <NUM> at the repair attachment section <NUM> is wider than a cropped width wc of the cropped airfoil <NUM> at the cropped airfoil attachment section <NUM>. In some embodiments, the repair attachment section <NUM> may be oversized with respect to the cropped airfoil attachment section <NUM> such that either the repair chord length cr is longer than the cropped chord length cc or the repair width wr is wider than the cropped width wc. In other embodiments, such as illustrated in <FIG>, both the repair chord length cr and the repair width wr are larger than the cropped chord length cc and the cropped width wc, respectively, i.e., the repair chord length cr is longer than the cropped chord length cc and the repair width wr is wider than the cropped width wc.

Like the chord length c described above, the repair chord length cr extends along the axial direction A from the repair leading edge <NUM> to the repair trailing edge <NUM> (or from the component first edge to the component second edge), and the cropped chord length cc extends along the axial direction A from the cropped leading edge 110c to the cropped trailing edge 112c (or from the cropped first edge to the cropped second edge). The width of each airfoil section is measured along the circumferential direction C, from the pressure side to the suction side. Thus, the repair width wr extends from the repair pressure side <NUM> to the repair suction side <NUM> (or between the component first side and component second side of the airfoil repair component <NUM>), and the cropped width wc extends along the circumferential C from the cropped pressure side 102c to the cropped suction side 104c (or between the cropped first side and the cropped second side of the cropped airfoil <NUM>). At least the repair attachment section <NUM> of the airfoil repair component <NUM> is oversized with respect to the cropped airfoil attachment section <NUM> of the cropped airfoil <NUM> such that the repair attachment section <NUM> extends beyond the cropped airfoil attachment section <NUM> axially or chordwise as well as circumferentially or widthwise.

Referring still to <FIG>, in at least some embodiments, the oversized repair attachment section <NUM> defines a flared extension of the body <NUM>. As shown in <FIG>, the repair attachment section <NUM> flares outward from the body <NUM>, with the repair width wr of the repair attachment section <NUM> wider than a body width wb of the body <NUM>. The flared or oversized repair attachment section <NUM> provides a larger repair joining face <NUM> than would be defined by a remainder of the body <NUM>, which provides a larger surface to align with the cropped joining face <NUM> that can help in aligning or positioning the airfoil repair component <NUM> with the cropped airfoil <NUM>. For example, the larger repair joining face <NUM> of the oversized repair attachment section <NUM> may be easier to align with the cropped joining face <NUM> than a joining face that was approximately the same size and shape as the cropped joining face <NUM> of the cropped airfoil <NUM>. That is, the flared, oversized repair attachment section <NUM> provides a larger land on the airfoil repair component <NUM> to improve initial part fitment allowance. The rest of the body <NUM> may be net shape, e.g., the flared extension defined by the repair attachment section <NUM> may be the only oversized portion of the airfoil repair component <NUM>, with the remainder of the airfoil repair component <NUM> being the same shape and size as the portion of the original airfoil <NUM> that the airfoil repair component <NUM> is replacing.

Turning to <FIG>, in some embodiments, the entire airfoil repair component <NUM> is oversized with respect to the cropped airfoil <NUM>. For instance, the body <NUM> of the airfoil repair component is oversized with respect to the cropped airfoil attachment section <NUM> such that the body <NUM> away from or outside of the repair attachment section <NUM> has a body chord length cb longer than the cropped chord length cc and a body width wb wider than the cropped width wc. In addition to the body <NUM>, the repair attachment section <NUM> is oversized with respect to the cropped airfoil attachment section <NUM> as described above, i.e., the repair chord length cr is longer than the cropped chord length cc, and the repair width wr is wider than the cropped width wc. As such, the airfoil repair component <NUM> may be overall larger than the cropped airfoil <NUM>.

As shown in <FIG>, the oversized, larger airfoil repair component <NUM> thus has "extra" or additional material, which may be machined away after the airfoil repair component <NUM> is attached to the cropped airfoil <NUM> to recover the desired net shape of the original undamaged airfoil <NUM>. That is, as illustrated in <FIG>, the net shape of the airfoil <NUM> is contained within the oversized airfoil repair component <NUM>, and the net shaped is revealed through processing (e.g., machining, deformation processing, etc.) after the airfoil repair component <NUM> is attached to the cropped airfoil <NUM>. In at least some embodiments, the oversized airfoil repair component <NUM> provides a greater margin of error in aligning the airfoil repair component <NUM> with the cropped airfoil <NUM>, e.g., as compared to an airfoil repair component <NUM> that is enlarged or oversized locally, such as only in the region of the repair attachment section <NUM>. For example, an airfoil repair component <NUM> that is enlarged or oversized overall (instead of a locally enlarged/oversized airfoil repair component <NUM>) may be used to repair a damaged airfoil <NUM> of a blisk <NUM> because there is less room to observe/detect and ensure the alignment of the airfoil repair component <NUM> with the cropped airfoil <NUM> on a blisk <NUM> because other airfoils <NUM> are adjacent the cropped airfoil <NUM>. The overall enlarged/oversized airfoil repair component <NUM> allows less precise placement of the airfoil attachment section <NUM> against the cropped airfoil attachment section <NUM> (e.g., compared to a locally enlarged or oversized airfoil repair component <NUM>, which may be used with a removable airfoil <NUM>) because the additional material can be machined away after attachment to define the shape of the airfoil <NUM>.

In contrast, the airfoil repair component <NUM> illustrated in <FIG> is locally enlarged or oversized, which an increased chord length cr and increased width wr only in the repair attachment section <NUM> as described above. The body <NUM> of the airfoil repair component <NUM> shown in <FIG> has the final shape of the airfoil <NUM>, i.e., the body <NUM> is shaped like the original, undamaged airfoil <NUM>. In at least some embodiments, the repair attachment section <NUM> is consumed as the airfoil repair component <NUM> is attached to the cropped airfoil <NUM> such that, unlike the overall enlarged/oversized airfoil repair component <NUM> of <FIG>, little to no processing is required once the airfoil repair component <NUM> is attached to the cropped airfoil <NUM> because the body <NUM> of the airfoil repair component <NUM> already defines the final shape of the airfoil <NUM>.

As shown in <FIG>, and <FIG>, the repair joining face <NUM> and the cropped joining face <NUM> interface in a plane-to-plane interaction. Stated differently, there is plane-to-plane contact between the airfoil repair component <NUM> and the cropped airfoil <NUM>. This interaction is designed to minimize the influence of alignment inaccuracies and counteract joining-induced stresses. When the airfoil repair component <NUM> is joined to the cropped airfoil <NUM> in a welding process, the repair joining face <NUM> and the cropped joining face <NUM> are consumed in the welding process as the two components are joined together. The planar interaction between the airfoil repair component <NUM> and the cropped airfoil <NUM> can help ensure the airfoil repair component <NUM> is properly aligned with respect to the cropped airfoil <NUM> to define the overall shape of the airfoil <NUM> once the joining process, and, if needed, any post-joining processing such as machining, deformation processing (e.g., cold or hot working, etc.), is complete.

Referring to <FIG>, the repair joining face <NUM> may include one or more projections <NUM> extending away from the repair joining face <NUM>, e.g., toward the cropped joining face <NUM> (<FIG>) when the airfoil repair component <NUM> is positioned with respect to the cropped airfoil <NUM> for joining the airfoil repair component <NUM> to the cropped airfoil <NUM>, such as shown in <FIG>. Additionally or alternatively, although not shown in <FIG>, the cropped joining face <NUM> may include one or more projections <NUM> extending away from the cropped joining face <NUM>, e.g., toward the repair joining face <NUM> when the airfoil repair component <NUM> is positioned with respect to the cropped airfoil <NUM> for joining the airfoil repair component <NUM> to the cropped airfoil <NUM>. The one or more projections <NUM> change the profile of the repair joining face <NUM> (and/or the cropped joining face <NUM>, where the cropped joining face <NUM> includes one or more projections <NUM> such as shown in <FIG> with respect to the repair joining face <NUM>), e.g., to help direct current during a joining process, and each projection <NUM> may have any suitable shape and size. As shown in <FIG>, the depicted projection <NUM> narrows the repair joining face <NUM> from the body <NUM> toward the cropped airfoil <NUM> such that a smaller surface area of the airfoil repair component <NUM> contacts the cropped airfoil <NUM>-e.g., compared to the surface area of the airfoil joining face <NUM> without the projection <NUM>-when the airfoil repair component <NUM> and cropped airfoil <NUM> are brought together for joining. Thus, the one or more projections <NUM>, which are consumed during the joining process, help localize the current when the joining process begins, which can help focus heat in a desired area early in the joining process.

In some embodiments, the airfoil <NUM> comprises a twist along the span S. For example, in <FIG> the root <NUM> of the airfoil <NUM> may be offset from the tip <NUM> of the airfoil <NUM> along the circumferential direction C such that, e.g., the leading edge <NUM> does not extend in a generally straight line from the root <NUM> to the tip <NUM>. The twist, offset, or deviation from linearity need not exist over the entire span S, e.g., the airfoil <NUM> may not have a twist along a length of the span S. For instance, in some embodiments such as depicted in <FIG>, the airfoil <NUM> may extend substantially linearly along the radial direction R from about mid-span to the tip <NUM>, i.e., the twist may be located between the root <NUM> and mid-span. Nonetheless, regardless of the location or degree of the twist, when repaired with an airfoil repair component <NUM>, the repaired airfoil <NUM> should also comprise a twist such that the repaired airfoil <NUM> has the same final shape as the original, undamaged airfoil <NUM>.

As illustrated in <FIG>, in at least some embodiments, the airfoil repair component <NUM> may be shaped to eliminate the twist in the repair attachment section <NUM>. For example, the repair attachment section <NUM> extends substantially straight or linearly along the radial direction R while the airfoil repair component <NUM> radially above the repair attachment section <NUM> incorporates a twist along the span S (<FIG>). In some embodiments, the cropped airfoil attachment section <NUM> of the cropped airfoil <NUM> also may be substantially straight or linear along the radial direction R. For instance, as shown at a location <NUM> in <FIG>, the twist may be removed, or the cropped airfoil <NUM> may be straightened, in the region of the cropped airfoil attachment section <NUM> using a localized coining operation or similar process. Having a straight or linear cropped airfoil attachment section <NUM> and/or repair attachment section <NUM> can help define a planar interaction between the cropped airfoil <NUM> and the airfoil repair component <NUM> along the cropped joining face <NUM> and the repair joining face <NUM>, which can help improve alignment between the cropped airfoil <NUM> and the airfoil repair component <NUM>. Further, the straight or linear cropped airfoil attachment section <NUM> and/or repair attachment section <NUM> are consumed during the joining process, e.g., as the airfoil repair component <NUM> is welded to the cropped airfoil <NUM>, such that the airfoil geometry that is modified to remove or be without the twist disappears during the joining process, leaving the repaired airfoil <NUM> with only the twist of the original airfoil <NUM>.

Although the flared or locally oversized airfoil repair component <NUM> is described with respect to an individual airfoil <NUM> (<FIG>) and the overall oversized repair component <NUM> is described with respect to a blisk <NUM> (<FIG>), it will be appreciated that the features described with respect to <FIG> and the features described with respect to <FIG> apply to airfoil repair components <NUM> for either individual airfoils <NUM> or airfoils <NUM> incorporated into a blisk <NUM>. That is, the illustrations provided herein are not intended to limit the application of the features shown therein. Further, the projections <NUM> likewise can be used for airfoil repair components <NUM> and/or cropped airfoils <NUM> for either individual airfoils <NUM> or airfoils <NUM> incorporated into a blisk <NUM>. Similarly, other features described herein, although shown or described with respect to individual airfoils <NUM> or blisk airfoils <NUM>, may be used for airfoil repair components <NUM> and/or cropped airfoils <NUM> for either individual airfoils <NUM> or airfoils <NUM> incorporated into a blisk <NUM>.

Turning now to <FIG>, in at least some embodiments, the airfoil repair component <NUM> is part of an airfoil repair system <NUM> (<FIG>, <FIG>). The airfoil repair system <NUM> includes components for locating, positioning, and holding the airfoil repair component <NUM> with respect to the cropped airfoil <NUM>. The airfoil repair system <NUM> also includes components facilitating the joining of the airfoil repair component <NUM> to the cropped airfoil <NUM>.

Referring particularly to <FIG>, the airfoil repair system <NUM> includes an electrode assembly <NUM>. The electrode assembly <NUM> comprises a repair component electrode <NUM> and a cropped airfoil electrode <NUM>. The repair component electrode <NUM> receives the airfoil repair component <NUM>, and the cropped airfoil electrode <NUM> receives the cropped airfoil <NUM>. As described herein, an electrical current is passed through the repair component electrode <NUM>, with the airfoil repair component <NUM> positioned therein, and the cropped airfoil electrode <NUM>, with the cropped airfoil <NUM> positioned therein, to join the airfoil repair component <NUM> to the cropped airfoil <NUM>. For example, a solid state resistance welding (SSRW) technique may be used to weld the airfoil repair component <NUM> to the cropped airfoil <NUM> by passing electrical current through the airfoil repair component <NUM> and the cropped airfoil <NUM> while the repair joining face <NUM> is in contact with (or is interfacing with) the cropped joining face <NUM>; the repair component electrode <NUM> and cropped airfoil electrode <NUM> also can provide a compressive axial force, e.g., toward the end of the current pulses, to help weld the airfoil repair component <NUM> and cropped airfoil <NUM>. Other welding or joining techniques or processes may be used as well.

Turning to <FIG>, in some embodiments, the cropped airfoil electrode <NUM> comprises a dovetail block <NUM>, an electrode body <NUM>, and a retention assembly <NUM>. As previously described, the cropped airfoil <NUM> formed from an individual or removable airfoil <NUM>, as illustrated in <FIG>, comprises a dovetail <NUM> that helps secure the airfoil <NUM> to a rotor disk. As depicted in <FIG>, the dovetail <NUM> is receivable within the dovetail block <NUM> of the cropped airfoil electrode <NUM>. For instance, the dovetail block <NUM> defines a dovetail opening <NUM> having a shape complementary to the shape of the dovetail <NUM>, and the dovetail <NUM> is received in the complementary shaped dovetail opening <NUM> of the dovetail block <NUM>. Thus, the dovetail block <NUM> helps secure and/or stabilize the cropped airfoil <NUM> within the cropped airfoil electrode <NUM> and constrains the cropped airfoil <NUM> along a stacking axis As (<FIG>) or along any longitudinal orientation where stabilization is beneficial to the joining process. The dovetail block <NUM> may or may not be constrained with respect to the cropped airfoil electrode <NUM>. For example, the dovetail block <NUM> may be locked into position using a set screw or the like, or no hard constraint may be placed on the dovetail block <NUM> such that it is free to move with respect to the cropped airfoil electrode <NUM>. It will be appreciated that in other embodiments, e.g., where the cropped airfoil <NUM> does not include a dovetail <NUM>, such as in blisk <NUM> embodiments, the dovetail block <NUM> of the cropped airfoil electrode <NUM> may be omitted.

Further, as depicted in <FIG>, the cropped airfoil <NUM> is removably secured to the electrode body <NUM> by one-handed manipulation of the retention assembly <NUM>. For example, the retention assembly <NUM> comprises a thrust element <NUM>, such as a lever or button, and a stop <NUM>, which may be a pin or the like. The thrust element <NUM> and the stop <NUM> are disposed opposite one another along the cropped chord length cc, e.g., when the cropped airfoil <NUM> is loaded in the cropped airfoil electrode <NUM>, one of the thrust element <NUM> and the stop <NUM> is disposed against the cropped leading edge 110c, and the other of the thrust element <NUM> and stop <NUM> is disposed against the cropped trailing edge 112c. The thrust element <NUM> may be manipulated by a user, e.g., using a single finger (such as a thumb) or a single hand, to load and unload the cropped airfoil <NUM> from the cropped airfoil electrode <NUM>. For instance, each of the thrust element <NUM> and the stop <NUM> provides a point constraint on the cropped airfoil <NUM>, and the thrust element <NUM> is manipulable, or moveable, to relax the point constraint provided by the thrust element <NUM> to load and/or unload the cropped airfoil <NUM> with respect to the cropped airfoil electrode <NUM>. More particularly, the thrust element <NUM> may be moved away from the cropped airfoil <NUM>, or the area where the cropped airfoil <NUM> is positioned when loaded into the electrode body <NUM>, to load and/or unload the cropped airfoil <NUM> from the cropped airfoil electrode <NUM>.

Referring now to <FIG>, in at least some embodiments, the airfoil repair component <NUM> similarly is removably secured to the repair component electrode <NUM>. For example, like the cropped airfoil electrode <NUM>, the repair component electrode <NUM> shown in <FIG> comprises an electrode body <NUM> and a retention assembly <NUM>. To differentiate between the electrode body <NUM> and the electrode body <NUM> more easily, in at least some instances herein, the electrode body <NUM> of the cropped airfoil electrode <NUM> may be referred to as the cropped airfoil electrode body <NUM>, and the electrode body <NUM> of the repair component electrode <NUM> may be referred to as the repair component electrode body <NUM>.

The airfoil repair component <NUM> is removably secured to the electrode body <NUM> by one-handed manipulation of the retention assembly <NUM>. In the embodiment of <FIG>, the retention assembly <NUM> comprises a thrust element <NUM>, such as a lever or button, and a stop <NUM>, which may be a pin or the like. The thrust element <NUM> and the stop <NUM> are disposed opposite one another along the repair chord length cr. For instance, when the airfoil repair component <NUM> is loaded in the repair component electrode <NUM>, one of the thrust elements <NUM> and stop <NUM> is disposed against the repair leading edge <NUM>, and the other of the thrust elements <NUM> and stop <NUM> is disposed against the repair trailing edge <NUM>.

The thrust element <NUM> may be manipulated by a user, e.g., using a single finger (such as a thumb) or a single hand, to load and unload the airfoil repair component <NUM> from the repair component electrode <NUM>. For example, each of the thrust element <NUM> and the stop <NUM> provides a point constraint on the airfoil repair component <NUM>. The thrust element <NUM> is manipulable, or moveable, to relax the point constraint provided by the thrust element <NUM> to load and/or unload the airfoil repair component <NUM> with respect to the repair component electrode <NUM>. That is, the thrust element <NUM> may be moved away from the airfoil repair component <NUM>, or the area where the airfoil repair component <NUM> is positioned when loaded into the electrode body <NUM>, to load and/or unload the airfoil repair component <NUM> from the repair component electrode <NUM>.

<FIG> and <FIG> illustrate another embodiment of the repair component electrode <NUM>. In the embodiment of <FIG> and <FIG>, the retention assembly <NUM> includes a stabilization element <NUM> defining an opening <NUM> that receives the airfoil repair component <NUM>, with a perimeter <NUM> extending about the opening <NUM>. Further, the stabilization element <NUM> includes a stabilization arm <NUM>, which contacts the repair suction side <NUM> to urge the airfoil repair component <NUM> into a first stop 328a contacting the repair pressure side <NUM>, and a second stop 328b, which provides at least a point constraint on the repair leading edge <NUM>. Referring particularly to <FIG>, the stabilization arm <NUM> includes a set screw <NUM> for tightening the stabilization arm <NUM> against the airfoil repair component <NUM>, with one or more springs used to retract the stabilization arm <NUM>. In this way, the smallest force may be used to hold the airfoil repair component <NUM> in place, such that the airfoil repair component <NUM> is not over-constrained. In other embodiments, other means may be used to advance and retract the stabilization arm <NUM> with respect to the airfoil repair component <NUM>.

In various embodiments, the components of the stabilization element <NUM> (i.e., perimeter <NUM>, stabilization arm <NUM>, first stop 328a, and second stop 328b) may provide point, line, and/or planar constraint on the airfoil repair component <NUM>, depending on, e.g., the configuration of the stabilization element component and the airfoil repair component <NUM>. It will be appreciated that the stabilization arm <NUM> may be manipulated to constrain or release the airfoil repair component <NUM>, with the perimeter <NUM>, stabilization arm <NUM>, first stops 328a, and second stop 328b of the stabilization element <NUM> providing sufficient constraint to stabilize the airfoil repair component <NUM> for the joining process without over-constraining the airfoil repair component <NUM>.

Turning now to <FIG>, the repair component electrode <NUM> comprises a repair component electrode insert <NUM> that surrounds at least a portion of the airfoil repair component <NUM> and is removable with respect to the repair component electrode body <NUM>. As shown in <FIG>, the repair component electrode insert <NUM> is received in the repair component electrode body <NUM>. In <FIG>, the repair component electrode insert <NUM> is shown removed from the repair component electrode body <NUM>.

As shown in <FIG>, the repair component electrode insert <NUM> defines an inert gas manifold <NUM> for receipt of an inert gas. Further, the repair component electrode insert <NUM> defines a first plurality of grooves 334a extending from the inert gas manifold <NUM> along a first outer surface 336a of the repair component electrode insert <NUM> and a second plurality of grooves 334b extending from the inert gas manifold <NUM> along a second outer surface 336b of the repair component electrode insert <NUM>. The first plurality of grooves 334a and the second plurality of grooves 334b direct the inert gas IG from the inert gas manifold <NUM> along a first side 338a and a second side 338b, respectively, of the repair component electrode insert <NUM> to define an inert gas shield around the airfoil repair component <NUM>.

An inert gas shield is useful, e.g., when the airfoil <NUM> and airfoil repair component <NUM> are formed from a reactive material, such as a titanium alloy or the like. For instance, a reactive material may have undesired reactions during some joining processes, such as solid state resistance welding (SSRW), which could contaminate the weld interface between the cropped airfoil <NUM>, the airfoil repair component <NUM>. By providing a shield or barrier of inert gas, the undesirable atmospheric reactions can be reduced or eliminated.

In the illustrated embodiment of <FIG> and <FIG>, the repair component electrode insert <NUM> engages both the leading edge and trailing edge profiles of the airfoil repair component <NUM>. That is, the repair component electrode insert <NUM> is shaped such that an inner surface <NUM> of the repair component electrode insert <NUM> engages both the repair leading edge <NUM> and the repair trailing edge <NUM>. Further, the repair component electrode insert <NUM> includes a leading edge guide 331a and a trailing edge guide 331b. The leading and trailing edge guides 331a, 331b are minimally conductive, high temperature and wear resistant guides that help stabilize the relatively thin edges of the airfoil repair component <NUM>, e.g., in titanium airfoil repair applications. For instance, the leading and trailing edge guides 331a, 331b hold the leading edge <NUM> and trailing edge <NUM>, respectively, to stabilize the airfoil repair component <NUM>. The leading and trailing edges guides 331a, 331b can also control heat and the leading edge <NUM> and trailing edge <NUM>, respectively, to help prevent overheating the leading and trailing edges <NUM>, <NUM> during the joining process. The leading and trailing edge guides 331a, 331b may be made from a material selected to minimize conduction, withstand high temperatures, and resist wear.

In the depicted embodiment, the repair component electrode insert <NUM> defines a cavity <NUM> for receipt of the airfoil repair component <NUM>. In some embodiments, only one of the repair leading edge <NUM> and the repair trailing edge <NUM>, or only a portion of one or both of the repair leading edge <NUM> and the repair trailing edge <NUM>, is engaged by the repair component electrode insert <NUM>. Engagement between the repair component electrode insert <NUM> and the airfoil repair component <NUM> can help stabilize airfoil repair component <NUM> within the repair component electrode <NUM> by preventing buckling or lapping of the thinner leading and trailing edges of the cropped airfoil <NUM> and/or the airfoil repair component <NUM>.

As further shown in <FIG>, in some embodiments the repair component electrode insert <NUM> comprises a first half 330a and a second half 330b. In the depicted embodiment, the repair component electrode insert <NUM> is divided chordwise or along the axial direction with respect to the airfoil repair component <NUM> to define the first half 330a and second half 330b. Each of the first half 330a and the second half 330b defines a portion of the inert gas manifold <NUM> such that together the two halves 330a, 330b define the inert gas manifold <NUM>.

Moreover, each of the first half 330a and the second half 330b of the depicted repair component electrode insert <NUM> defines a portion of the plurality of grooves <NUM>. More particularly, the first half 330a defines a first plurality of grooves 334a of the plurality of grooves <NUM>, and the second half 330b defines a second plurality of grooves 334b of the plurality of grooves <NUM>. Each of the first plurality of grooves 334a and the second plurality of grooves 334b extends from the inert gas manifold <NUM> along the respective first half 330a and second half 330b of the repair component electrode insert <NUM>.

As illustrated in the embodiment of <FIG>, each groove <NUM> of the plurality of grooves <NUM> extends parallel to the remaining grooves <NUM> of the plurality of grooves <NUM>. In other embodiments, the plurality of grooves <NUM> may not all be parallel to one another, but instead, at least one groove <NUM> of the plurality of grooves <NUM> may extend in a different direction with respect to one or more of the plurality of grooves <NUM>. Further, the plurality of grooves <NUM> may be generally symmetric with respect to the repair component electrode insert <NUM>. For example, for the halved repair component electrode insert <NUM> shown in <FIG>, the number of the first plurality of grooves 334a equals the number of the second plurality of grooves 334b, and each respective groove 334a of the first plurality of grooves 334a is defined across from a respective groove 334b of the second plurality of grooves 334b along the widthwise dimension of the airfoil repair component <NUM>. However, in other embodiments, the plurality of grooves <NUM> may not be symmetric, e.g., a different number of grooves 334a may be defined in the first half 330a than the number of grooves 334b defined in the second half 330b.

Referring to <FIG>, in at least some embodiments, the repair component electrode <NUM> includes serrations <NUM> defined in the repair component electrode body <NUM>. The serrations <NUM> are openings or areas without material in the repair component electrode body <NUM>. As shown in <FIG>, each serration <NUM> includes a change in direction, e.g., a serration <NUM> includes a first portion angling from a first side of the repair component electrode body <NUM> toward an opposite second side of the repair component electrode body <NUM> and a second portion angling from the second side of the repair component electrode body <NUM> toward the opposite first side of the repair component electrode body <NUM>. The serrations <NUM> can act like a spring or other biased member to achieve better or improved contact between the repair component electrode <NUM> and the airfoil repair component <NUM>. Further, the serrations <NUM> can provide cooling, especially at the leading edge <NUM> and/or trailing edge <NUM> of the airfoil repair component <NUM> during the joining process, e.g., to protect the relatively thin leading edge <NUM> and trailing edge <NUM>. For example, the serrations <NUM> can throttle or choke current passing through the repair component electrode <NUM> to the airfoil repair component <NUM> at the leading edge <NUM> and/or trailing edge <NUM> to help avoid overheating the leading edge <NUM> and/or trailing edge <NUM> as the airfoil repair component <NUM> is joined to the cropped airfoil <NUM>.

Turning now to <FIG>, <FIG>, and <FIG>, the airfoil repair system <NUM> includes a tooling assembly <NUM> for positioning the airfoil repair component <NUM> with respect to the cropped airfoil <NUM>. Referring particularly to <FIG>, in at least some embodiments, the tooling assembly <NUM> comprises an alignment assembly <NUM>. In the embodiment of <FIG>, the alignment assembly <NUM> is an independent axis three degree-of-freedom manipulator configured to adjust the position of the airfoil repair component <NUM> (enclosed within the repair component electrode <NUM> in <FIG>) with respect to the cropped airfoil <NUM> (enclosed within the cropped airfoil electrode <NUM> in <FIG>) along three separate axes defined by the cropped airfoil <NUM>. As shown, the alignment assembly <NUM> includes a first rotatable knob 348a, which adjusts the position of the airfoil repair component <NUM> along a first degree of freedom, the axial direction A or chordwise along the cropped airfoil <NUM>; a second rotatable knob 348b, which adjusts the position of the airfoil repair component <NUM> along a second degree of freedom, the circumferential direction C or widthwise along the cropped airfoil <NUM>; and a third rotatable knob 348c, which adjusts the position of the airfoil repair component <NUM> with respect to a third degree of freedom, the stacking axis AS. Using rotatable knobs 348a, 348b, 348c to adjust the position of the airfoil repair component <NUM> may allow more precise alignment of the airfoil repair component <NUM> with respect to the cropped airfoil <NUM> than other modes of alignment. However, it will be appreciated that, in addition to or in place of rotatable knobs, in other embodiments the alignment assembly <NUM> may utilize other means for adjusting the position or alignment of the airfoil repair component <NUM> along the various degrees of freedom. It will be appreciated that the illustrated alignment assembly <NUM> is by way of example only. In other embodiments, the alignment assembly <NUM> can manipulate or adjust the position of the airfoil repair component <NUM> and/or the cropped airfoil <NUM> in any number of degrees of freedom, e.g., less or more than three.

Further, using the alignment assembly <NUM>, the airfoil repair component <NUM> may be tilted or biased with respect to the cropped airfoil <NUM>, e.g., to help ensure a desired geometry of the joined airfoil repair component <NUM> and cropped airfoil <NUM>. For example, the position of the airfoil repair component <NUM> may be manipulated along one or more degrees of freedom to control the post-joining (e.g., post-weld) geometry, which can minimize or eliminate post-joining cold working. As such, the alignment assembly <NUM> can help position the airfoil repair component <NUM> with respect to the cropped airfoil <NUM> (e.g., with a few degrees of tilt, such as within a range of <NUM>°-<NUM>° with respect to the axial direction A, radial direction R, and/or circumferential direction C, or the like) to closely resemble or approximate the post-joining geometry of the airfoil <NUM>.

Referring now to <FIG>, in at least some embodiments, the tooling assembly <NUM> comprises a feedback system <NUM> including at least one feedback device <NUM> located to determine a position of the airfoil repair component <NUM> with respect to the cropped airfoil <NUM> and/or to determine the size (e.g., height, width, and/or thickness) of the airfoil repair component <NUM>, repair component electrode <NUM>, etc. Determining the size of the respective component may be referred to as on-machine probing, in which one determines the size of a component and then decides where to position the component for a desired process.

In the embodiment of <FIG>, the feedback system <NUM> includes a first feedback device 352a and a second feedback device 352b positioned radially outward from the electrode assembly <NUM>. The first feedback device 352a and the second feedback device 352b may provide feedback as to the position of the repair component electrode <NUM> (in which the airfoil repair component <NUM> is disposed) with respect to the cropped airfoil electrode <NUM> (in which the cropped airfoil <NUM> is disposed), or with respect to another reference point or component within the airfoil repair system <NUM>, and/or as to the size of the airfoil repair component <NUM> and/or the repair component electrode <NUM>. The feedback can be used to ascertain whether the airfoil repair component <NUM> is properly aligned with the cropped airfoil <NUM> prior to a joining process and, if not, may assist in repositioning the airfoil repair component <NUM> until the airfoil repair component <NUM> is adequately aligned with the cropped airfoil <NUM> to begin the joining process. It will be appreciated that the one or more feedback devices, such as the first feedback device 352a and the second feedback device 352b, may be cameras, non-contact or contact-type gages, non-contact or contact-type measurement devices, or the like or a combination thereof that provide images, location data, and/or other data to a user interface, controller, etc. to allow a user or operator, a controller, etc. to manually or automatically initiate repositioning of the airfoil repair component <NUM> or the start of the joining process. Further, although not shown in <FIG>, the feedback system <NUM> may be supported by a frame or other support system that allows the electrode assembly <NUM> to be removed from and replaced within the field of view or field of sensing of the at least one feedback device <NUM>, e.g., after one airfoil repair component <NUM> is joined to one cropped airfoil <NUM> and another airfoil repair component <NUM> is prepared to be joined to another cropped airfoil <NUM>.

Turning to <FIG>, a cropped airfoil portion 344C of the tooling assembly <NUM> for stabilizing the cropped airfoil <NUM> of a blisk <NUM> is illustrated. As shown in <FIG>, in at least some embodiments, the cropped airfoil portion 344C of the tooling assembly <NUM> includes a frame <NUM> that supports a hoop clamp <NUM>, a hydraulic clamp assembly <NUM> including an electrode element <NUM> and hydraulic cylinder <NUM>, and a band electrode <NUM>. The hoop clamp <NUM> and hydraulic clamp assembly <NUM> stabilize the cropped airfoil <NUM>, e.g., such that the airfoil repair component <NUM> can be aligned with the cropped airfoil <NUM> to perform a joining operation. The hoop clamp <NUM> is not directly coupled to the frame <NUM> but is joined to the frame <NUM> in such a way to avoid inducing any significant stress and/or distortion to the frame <NUM>, which helps ensure the highest level of accuracy while utilizing the least total material. As depicted in <FIG>, the electrode element <NUM> of the hydraulic clamp assembly <NUM> extends from the hydraulic cylinder <NUM> and presses the cropped airfoil <NUM> into the band electrode <NUM>, which is supported by the hoop clamp <NUM> such that the cropped airfoil <NUM> is pressed into the hoop clamp <NUM>.

Further, the hoop clamp <NUM> extends about the hydraulic clamp assembly <NUM> and is free to slide within the frame <NUM>, and the hydraulic cylinder <NUM> is supported by the frame <NUM>. For example, in the arrangement depicted in <FIG>, the hoop clamp <NUM> applies an enclosed structural loop of squeezing force to reduce or eliminate bending stress from the frame <NUM> and other interrelated tooling components. Thus, the tooling assembly <NUM> decouples the holding elements from the electrodes to help eliminate the bending moment on the cropped airfoil <NUM> and airfoil repair component <NUM>.

Moreover, one or more openings <NUM> may be formed in the hoop clamp <NUM>, as well as other components of the cropped airfoil portion 344C of the tooling assembly <NUM>, to accommodate airfoils <NUM> of the blisk <NUM> that are adjacent the cropped airfoil <NUM>. It will be appreciated that the tooling assembly cropped airfoil portion 344C may be made as compact as possible, e.g., for easier post-joining extraction of the blisk <NUM>, and the cropped airfoil portion 344C captures the cropped airfoil 140to position the blisk <NUM> and the cropped airfoil <NUM> with respect to the airfoil repair component <NUM>. Further, the cropped airfoil portion 344C of the tooling assembly <NUM> can help stabilize the cropped airfoil electrode <NUM> and help ensure contact between the cropped airfoil <NUM> and the cropped airfoil electrode <NUM>. Additionally, the cropped airfoil portion 344C of the tooling assembly <NUM> helps align the airfoil repair component <NUM> with the blisk <NUM> and its cropped airfoil <NUM>, e.g., as shown in <FIG>.

<FIG> provides a side perspective view of the tooling assembly <NUM>, including airfoil-side tooling, i.e., the cropped airfoil portion 344C, and airfoil repair component-side tooling, i.e., the airfoil repair component portion 344R. For example, the tooling assembly <NUM> as illustrated in <FIG> may be used to stabilize a blisk <NUM> and an airfoil repair component <NUM>, with the respective repair component electrode <NUM> and cropped airfoil electrode <NUM>, while joining the airfoil repair component <NUM> to a cropped airfoil <NUM> of the blisk <NUM>. As such, as shown in <FIG>, the cropped airfoil portion 344C of the tooling assembly <NUM> (or segments thereof) may be mounted onto a slide rail <NUM>, or other similar support element, to help move the blisk <NUM> with respect to the airfoil repair component portion 344R of the tooling assembly <NUM>. As further depicted in <FIG>, the feedback system <NUM> may be mounted vertically below the cropped airfoil <NUM> and airfoil repair component <NUM> in the tooling assembly <NUM>. It will be appreciated that, in other embodiments, the feedback system <NUM> may be mounted or supported at any suitable location of the airfoil repair system <NUM>, e.g., above, below, on one side, at an angle relative to the airfoil repair system <NUM>, or one or more components of the feedback system <NUM> may be mounted in one location while one or more components of the feedback system <NUM> are mounted in one or more different locations.

Referring now to <FIG>, the present subject matter also provides methods of repairing an airfoil. As shown in <FIG>, a method <NUM> of repairing an airfoil <NUM> comprises (<NUM>) removing a damaged portion <NUM> of the airfoil <NUM> to form a cropped airfoil <NUM>. As described herein, the damaged portion <NUM> may include a damaged area <NUM>, which is a hollow area or cavity such as an opening, crack, gap, aperture, hole, etc. in the airfoil <NUM>. For instance, as described with respect to <FIG>, the airfoil <NUM> may include a section line SL, which may be, e.g., one half of the distance between the tip <NUM> at the leading edge and a leading edge fillet tangency T. The damaged portion <NUM> (including the damaged area <NUM>) may be removed above, below, or at (or radially outward from, radially inward from, or at) the section line SL.

Further, the method <NUM> may comprise (<NUM>) locally removing a spanwise twist from the cropped airfoil <NUM>, which also may be referred to as coining the cropped airfoil <NUM> to remove the twist along at least a portion of the airfoil span S. As described herein, e.g., with respect to <FIG>, in at least some embodiments, the cropped airfoil <NUM> may be shaped to eliminate the twist in the cropped airfoil attachment section <NUM>, and the airfoil repair component <NUM> may be shaped to eliminate the twist in the repair attachment section <NUM>. For example, each of the cropped airfoil attachment section <NUM> and the repair attachment section <NUM> extends substantially straight or linearly along the radial direction R while the remainder of the cropped airfoil <NUM> and the airfoil repair component <NUM> incorporates a twist along the span S. Having a straight or linear cropped airfoil attachment section <NUM> and/or repair attachment section <NUM> can help define a planar interaction or surface or area contact between the cropped airfoil <NUM> and the airfoil repair component <NUM> along the cropped joining face <NUM> and the repair joining face <NUM>, which can help improve alignment between the cropped airfoil <NUM> and the airfoil repair component <NUM>. Further, the straight or linear section cropped airfoil attachment section <NUM> and/or repair attachment section <NUM> are consumed during the joining process, e.g., as the airfoil repair component <NUM> is welded to the cropped airfoil <NUM>, such that, during the joining process, the airfoil geometry that is modified to remove or be without the twist is expelled from the weld interface in the form of weld flash, and the repaired airfoil <NUM> has the twist of the original airfoil <NUM>. It will be appreciated that, in other embodiments, the original airfoil <NUM> may not include a spanwise twist such that (<NUM>) locally removing the spanwise twist may be omitted from the method <NUM>.

Referring still to <FIG>, the method <NUM> further comprises (<NUM>) disposing the cropped airfoil <NUM> in a cropped airfoil electrode <NUM> and (<NUM>) disposing an airfoil repair component <NUM> within a repair component electrode <NUM>. The cropped airfoil <NUM>, airfoil repair component <NUM>, repair component electrode <NUM>, and cropped airfoil electrode <NUM> are configured as described herein, e.g., with respect to <FIG>. The repair component electrode <NUM> and cropped airfoil electrode <NUM> are of an electrode assembly <NUM>, and and the repair component electrode <NUM> comprises a repair component electrode insert <NUM> removably received within a repair component electrode body <NUM>. The repair component electrode insert <NUM> includes an inert gas manifold <NUM> and a plurality of grooves <NUM> for creating an inert gas shield around the airfoil repair component <NUM>.

The method <NUM> also may include (<NUM>) positioning the airfoil repair component <NUM> with respect to the cropped airfoil <NUM>. As described herein, in at least some embodiments, positioning the airfoil repair component <NUM> with respect to the cropped airfoil <NUM> comprises locating the repair component electrode <NUM> using a feedback system to ascertain a position of the airfoil repair component <NUM> with respect to the cropped airfoil <NUM>. For example, the feedback system <NUM> may include one or more feedback devices <NUM>, such as cameras, measurement gages, or the like, positioned about the electrode assembly <NUM> to provide feedback as to the position of the repair component electrode <NUM> with respect to the cropped airfoil electrode <NUM>.

Further, in at least some embodiments, positioning the airfoil repair component <NUM> with respect to the cropped airfoil <NUM> comprises manipulating an alignment assembly <NUM>, such as an independent axis degree-of-freedom manipulator, to reposition the airfoil repair component <NUM> and/or the cropped airfoil <NUM> along one axes, e.g., defined by the cropped airfoil <NUM>. For instance, the alignment assembly <NUM> may comprise three rotatable knobs, e.g., a first knob 348a, a second knob 348b, and a third knob 348c, where each knob 348a, 348b, 348c adjusts or manipulates the position of the repair component electrode <NUM> with respect to the cropped airfoil electrode <NUM> along one degree-of-freedom.

As further illustrated in <FIG>, the method <NUM> may comprise (<NUM>) conducting a joining process to join the airfoil repair component <NUM> to the cropped airfoil <NUM>, thereby replacing the damaged portion <NUM> removed from the airfoil <NUM> with the airfoil repair component <NUM>. In at least some embodiments, the joining process comprises passing current through the cropped airfoil electrode <NUM> and the repair component electrode <NUM> to attach the airfoil repair component <NUM> to the cropped airfoil <NUM> and form a repaired airfoil. For example, passing current through the cropped airfoil electrode <NUM> and the repair component electrode <NUM> comprises welding the airfoil repair component <NUM> to the cropped airfoil <NUM> through solid state resistance welding. In other embodiments, other suitable methods for joining the airfoil repair component <NUM> to the cropped airfoil <NUM> may be used.

Further, for embodiments utilizing current to join the airfoil repair component <NUM> to the cropped airfoil <NUM>, the airfoil repair system <NUM> may incorporate adaptive current control to improve yield. For instance, the airfoil repair system <NUM> may utilize weld luminescence and/or thermal imaging and a controller or the like to analyze and adjust the supplied current, e.g., to match the weld uniformity to a predetermined weld uniformity. The current may be adjusted, e.g., through manipulation of a pulsing sequence. By adjusting the weld during the joining process, increased yield or repair success may be achieved.

Additionally, or alternatively, the airfoil repair system <NUM> may utilize a variety of power sources. For example, for a resistance welding joining process (such as solid state resistance welding), the airfoil repair system <NUM> may utilize single-phase alternating current (AC), primary and secondary rectified direct current (DC), capacitive discharge (CD), or medium frequency DC (MFDC). MFDC, for instance, may allow finer current control, faster rise time, and a smaller footprint than AC and DC power sources. However, AC, DC, and CD power may provide advantages over MFDC for some applications of the airfoil repair system <NUM>.

Referring still to <FIG>, the method <NUM> also may comprise (<NUM>) obtaining a net shape finished part from the repaired airfoil <NUM>. For example, the method <NUM> may include post-joining processing to achieve the net shape of the original airfoil <NUM> from the repaired airfoil <NUM>. For instance, after joining the airfoil repair component <NUM> to the cropped airfoil <NUM>, the repaired airfoil <NUM>, including the airfoil repair component <NUM>, may be machined (e.g., milled or the like) to obtain the net shape of the original airfoil <NUM>. As described herein, the airfoil repair component <NUM> may be locally oversized, e.g., in the region of the repair attachment section <NUM>, or wholly oversized (i.e., the entire airfoil repair component <NUM> is oversized), such that at least a portion of the airfoil repair component <NUM> does not have the net shape of the airfoil <NUM>. It will be appreciated that the term "oversized" refers to additional material of the airfoil repair component <NUM> that may provide increased margin or tolerance for alignment between the cropped airfoil <NUM> and the airfoil repair component <NUM> such that the two components do not have to be precisely aligned. For instance, the extra material of the oversized airfoil repair component <NUM> allows misalignment between the airfoil repair component <NUM> and the cropped airfoil <NUM> to be corrected through finish machining, e.g., the repair pressure side <NUM> or repair suction side <NUM> may be machined more or less than the other of the repair pressure side <NUM> and repair suction side <NUM> to compensate for widthwise misalignment. As another example, rather than machining after joining, the repaired airfoil <NUM> may undergo other post-joining processing, such as cold working or other deformation processing, to transform a non-conforming airfoil to a net shape part. In such embodiments, the repaired airfoil <NUM> may be largely the desired shape post-joining but may require some cold-working to shape the airfoil <NUM> within desired limits.

The airfoil repair component <NUM> may be oversized at least in the vicinity of where the airfoil repair component <NUM> is joined to the cropped airfoil <NUM>, such that at least a portion of the oversized section of the airfoil repair component <NUM> may be consumed in the joining process. After joining the airfoil repair component <NUM> and the cropped airfoil <NUM>, the portions of the airfoil repair component <NUM> that remain oversized may be machined to define the desired shape of the airfoil <NUM>. As described herein, the airfoil repair component <NUM> for an individual airfoil <NUM> (having a platform and dovetail, e.g., as shown in <FIG>) may be locally oversized while the airfoil repair component <NUM> for an airfoil <NUM> of a blisk <NUM> may be oversized all over, e.g., to minimize the risk of damaging the entire blisk <NUM> during repair of one blisk airfoil. Of course, in some embodiments, the airfoil repair component <NUM> for an individual airfoil <NUM> may be wholly oversized while the airfoil repair component <NUM> for an airfoil <NUM> of a blisk <NUM> may be locally oversized.

Various features of the airfoil repair component <NUM> and/or airfoil repair system <NUM> may be described or shown herein with respect to either an individual airfoil or a blisk airfoil. However, it will be appreciated that at least certain features of the airfoil repair component <NUM> and/or airfoil repair system <NUM> may apply to both configurations although shown and/or described herein with respect to only one configuration. Additionally, it will be understood that the various features of the airfoil repair component <NUM> and/or airfoil repair system <NUM> may be utilized in additional and/or alternative combinations than those shown and described herein.

Further, it will be appreciated that, although described above with respect to airfoil repairs, the present subject matter also could be used with respect to initial or new build parts. For example, the airfoil repair component <NUM> could, instead, be referred to as an airfoil component <NUM>, which is joined to a cropped or base airfoil <NUM> to form a whole or complete airfoil <NUM>. The airfoil component <NUM> can be formed as described herein as airfoil repair component <NUM>, e.g., the airfoil component <NUM> can have a flared attachment section <NUM> or a body <NUM> that is overall oversized, and the airfoil component <NUM> has a component pressure side <NUM> opposite a component suction side <NUM> (or a component first side and a component second side) that each extend axially between a component leading edge <NUM> and a component trailing edge <NUM> (or a component first edge and a component second edge). For instance, the attachment section <NUM> attaches the airfoil component <NUM> to the cropped or base airfoil <NUM> and is oversized with respect to a cropped airfoil attachment section <NUM> such that the attachment section <NUM> has a component chord length cr longer than a cropped chord length cc of the cropped airfoil attachment section <NUM> and a component width wr wider than a cropped width wc of the cropped airfoil attachment section <NUM>. Further, the airfoil component <NUM> can be received in an electrode like the repair component electrode <NUM>, which may be referred to as an airfoil component electrode <NUM>, and be positioned with the cropped or base airfoil <NUM> in its cropped airfoil electrode <NUM> using a tooling assembly <NUM> as described herein. Joining an airfoil component <NUM> to a cropped or base airfoil <NUM> may be useful, e.g., for some configurations of a blisk <NUM>, where certain size airfoils <NUM> may be easier to manufacture as a blisk <NUM> using the joining techniques and features described herein.

Claim 1:
A method of repairing an airfoil comprising:
disposing (<NUM>) a cropped airfoil (<NUM>) in a cropped airfoil electrode (<NUM>);
disposing (<NUM>) an airfoil repair component (<NUM>) within a repair component electrode (<NUM>), the repair component electrode comprising a repair component electrode insert (<NUM>) removably received within a repair component electrode body (<NUM>);
positioning (<NUM>) the airfoil repair component with respect to the cropped airfoil;
characterised in:
passing an inert gas to the repair component electrode via an inert gas manifold (<NUM>) defined in the repair component electrode; and
conducting (<NUM>) a joining process to attach the airfoil repair component to the cropped airfoil and form an airfoil.