METHOD INVOLVING FRICTION PLUG WELDING A FLANGE

A method is provided that involves a component including a first fastener aperture that extends through the component. During the method, the component is machined to enlarge the first fastener aperture to provide an enlarged aperture. The component is friction plug welded to plug the enlarged aperture with friction plug welded material. A second fastener aperture is machined in the friction plug welded material, where the second fastener aperture extends through the component.

BACKGROUND OF THE INVENTION

1. Technical Field

This disclosure relates generally to a repairing or reconfiguring a fastener aperture in a component.

2. Background Information

A modern commercial gas turbine engine may include an aluminum fan case. Flanges with multiple bolt holes at each end of the fan case are used to secure that case to neighboring components. After operation of the gas turbine engine, some of the bolt holes may be damaged due to corrosion and/or other causes and need repair. These damaged bolt holes may be repaired using conventional arc welding processes. However, there are technical challenges associated with arc welding processes. The weld metal property of aluminum alloy from an arc welding process is known to be much lower than the base metal. The melting and solidification inherently associated with the arc welding process can create weld defects such as porosity or lack of fusion. Aluminum alloy is known to be prone to the formation of such weld defects. The formation of weld defects in aluminum alloy may further reduce the capability of aluminum alloy weld and make the aluminum alloy weld unable to meet the performance requirements especially when the weld metal property is needed to be closer to that of the base metal.

There is a need in the art for an improved method for repairing damaged bolt holes in a case of a gas turbine engine.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present disclosure, a method is provided involving a component comprising a first fastener aperture that extends through the component. During this method, the component is machined to enlarge the first fastener aperture to provide an enlarged aperture. The component is friction plug welded to plug the enlarged aperture with friction plug welded material. A second fastener aperture is machined in the friction plug welded material, where the second fastener aperture extends through the component.

According to another aspect of the present disclosure, another method is provided involving a tubular fan case structure of a gas turbine engine, where the fan case structure includes an annular flange and a first fastener aperture that extends through the flange, and where the flange is configured from or otherwise includes metallic material. During the method, the first fastener aperture is enlarged to provide an enlarged aperture. The flange is friction plug welded to plug the enlarged aperture with friction plug welded material. A second fastener aperture is drilled in the friction plug welded material.

According to still another aspect of the present disclosure, another method is provided involving a component including a defect or otherwise damaged portion. During the method, the defect (or otherwise damaged portion) is drilled out to remove the defect (or otherwise damaged portion) from the component and provide an aperture. The component is friction plug welded to plug the aperture with friction plug welded material.

During the method, a fastener aperture may be machined in the friction plug welded material. The fastener aperture may extend through the component.

The defect may be a crack, a fracture, a porous region, a pitted region, a worn region, a corroded region, etc.

The component may include a flange. The first fastener aperture may extend along an axis through the flange.

The friction plug welding may include: spinning a plug about a longitudinal axis of the plug; and moving the spinning plug along the longitudinal axis into the enlarged aperture.

The moving of the spinning plug may include pushing or pulling the spinning plug along the longitudinal axis into the enlarged aperture.

A portion of the friction plug welded material may be removed before the machining (e.g., drilling) of the second fastener aperture, where the portion projects out from the component (e.g., flange); e.g., from a surface of the flange.

The machining of the component (e.g., flange) may include removing a damaged portion of the component. In addition or alternatively, the machining of the component (e.g., flange) may include removing pitted material from the component. In addition or alternatively, the machining of the component (e.g., flange) may include removing corroded material from the component.

The first fastener aperture may have a first cross-sectional area. The second fastener aperture has a second cross-sectional area that is different the first cross-sectional area.

The first fastener aperture may have a first cross-sectional shape. The second fastener aperture may have a second cross-sectional shape that is different from the first cross-sectional shape.

The first fastener aperture may extend axially through the component (e.g., flange) along a first axis. The second fastener aperture may extend axially through the component (e.g., flange) along a second axis which is substantially co-axial with the first axis.

The component may be configured from or otherwise include an aluminum alloy.

The component may be configured from or otherwise include a case for a gas turbine engine.

A fan case structure for the gas turbine engine may include the case.

The component may be configured from or otherwise include metallic material and composite material attached to the metallic material. The metallic material may form the flange.

The method may be performed without heat treating the component (e.g., flange) before or after the friction plug welding.

During the method, the component (e.g., flange) may be heat treated after the friction plug welding and, in some embodiments, after the drilling of the second fastener aperture.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure includes devices, systems and methods for repairing, reconfiguring and/or otherwise working on a component with one or more apertures. The component may be repaired, for example, to restore at least one aperture and/or an area near that aperture to meet its intended application; e.g., shape, dimension, finish, etc. In another example, the component may be reconfigured to modify at least one aperture and/or an area near that aperture to meet a new application.

An exemplary embodiment of a component20is schematically illustrated inFIGS. 1 and 2. This component20is configured as a tubular case for a gas turbine engine, which case may be an axial segment of a tubular fan case structure for the gas turbine engine. The present disclosure, however, is not limited to the foregoing exemplary component configuration, or to gas turbine engine applications.

The component20ofFIGS. 1 and 2is configured having a tubular, full hoop body. The component20extends circumferentially around an axial centerline22; e.g., a centerline of a gas turbine engine. The component20extends axially along the centerline22between opposing component ends24.

The component20includes a tubular base26and one or more annular flanges28. The component20may also include a tubular liner30. The component20may also or alternatively also include one or more other members/structures radially outside and/or inside of the base26structure.

The base26extends circumferentially around the centerline22and circumscribes the liner30. The base26extends axially along the centerline22between the opposing component ends24.

Each of the flanges28extends circumferentially around the centerline22and circumscribes the base26. Each of the flanges28extends axially between opposing flange side surfaces32. Each of the flanges28projects, for example radially outward, from the base26to a distal end34. One of the flanges28is disposed at (e.g., on, adjacent or proximate) one of the component ends24. The other one of the flanges28is disposed at the other one of the component ends24.

Each of the flanges28includes one or more fastener apertures36. The fastener apertures36associated with each flange28are arranged about the centerline22in a respective annular array. Each of the fastener apertures36extends along a respective axis38through the flange28between the opposing flange side surfaces32. The term “fastener aperture” may describe a hole configured to receive a fastener such as a screw, bolt, stud, rivet, etc.

Each of the flanges28is connected to the base26. Each of the flanges28, for example, may be formed integral with the base26such that the base26and the flanges28are part of a unitary, monolithic body. This body is for tried from or otherwise includes metallic material such as, but not limited to, aluminum (Al), aluminum alloy, nickel (Ni)-based super alloy, nickel based alloy, titanium (Ti) alloy, cobalt (Co)-based alloy, or stainless steel.

The liner30is a structure within the base26structure; e.g., a case structure. The liner30may be configured as or otherwise include one or more acoustic panels (e.g., noise attenuating panels), one or more anti-icing panels, etc. The liner30extends circumferentially around the centerline22within a bore of the base26. The liner30extends axially along the centerline22, for example, between the opposing component ends24. The liner30may be formed discrete from the base26, but engaged with an interior surface40of the base26that forms the bore after assembly. The liner30, for example, may be mechanically fastened, welded, brazed, adhered with an adhesive (e.g., epoxy, resin, etc.) and/or otherwise attached to the base26adjacent the interior surface40. The liner30may be formed from or otherwise include metallic material and/or composite material.

Each fastener aperture36in each flange28is configured to receive a respective one of a plurality of fasteners (not shown), where each fastener extends into a respective one of the fastener apertures36. The fasteners attach the component20with at least one other component; e.g., an adjacent axial segment of the fan case structure. During operation, each of the flanges28may be subject to various forces, internal stresses and/or exposure to certain environmental conditions that may wear or otherwise damage the flange28. Such damage may alter the configuration (e.g., shape, dimension, etc.) of one or more of the fastener apertures36and/or the configuration (e.g., dimension, surface finish, internal structure, etc.) of the flange areas forming and/or near those fastener apertures36. Exemplary embodiments of such damage to the flange28is illustrated inFIGS. 3A-3C.

FIG. 3Adepicts the flange28with a fastener aperture according to original specification (see dotted line42) overlaid with the fastener aperture after the flange28forming that aperture is worn (see solid line44). In this embodiment, the flange28is worn in such a manner so as to increase a cross-sectional dimension (e.g., radius) of the fastener aperture36.

FIG. 3Bdepicts the flange28with a fastener aperture according to original specification (see dotted line46) overlaid with the fastener aperture after the flange28forming that aperture is worn (see solid line48). In this embodiment, the flange28is worn in such a manner so as to increase a cross-sectional dimension (e.g., radius) of the fastener aperture36as well as change a cross-sectional shape of the fastener aperture36from a circular shape to an oval shape.

FIG. 3Cdepicts the flange28with a fastener aperture (see solid line50), which flange28may or may not have been worn as described above with respect toFIG. 3A, 3Bor otherwise.FIG. 3Calso depicts the flange28with a damaged portion (see area between dotted line52and solid line50), which may at least partially form and/or be near (e.g., surround) the fastener aperture36. This damaged portion of the flange28may include pitting, cracks, fractures, corrosion and/or other defects in the flange28material.

FIG. 4is a flow diagram of a method400involving a component such as the component20described above and shown inFIGS. 1 and 2. For ease of description, the method400is described below as repairing a damaged portion of the flange28as described above with respect toFIG. 3A. However, the method400may also be performed to repair, reconfigure or otherwise work on a portion of the flange28as described above with respect toFIG. 3B, 3Cand/or otherwise.

In step402, the flange28is machined to enlarge a damaged fastener aperture36A (seeFIG. 5) to provide an enlarged aperture54(seeFIG. 6). The damaged fastener aperture36A ofFIG. 5, for example, may be drilled out with a drill bit to provide the enlarged aperture54ofFIG. 6. This machining step402may be used to provide the aperture54with a predetermined cross-sectional dimension (e.g., radius). The machining step402may also be used to provide the aperture54with a predetermined shape, particularly where damage to the flange28changes the geometry of the aperture36as shown inFIG. 3B.

In step404, the flange28is friction plug welded to plug the enlarged aperture54with friction plug welded material56as shown byFIGS. 7-9. For example, referring toFIG. 7, an elongated plug58(e.g., a partially tapered pin) is held within a chuck of a tool60, where the plug58has a larger cross-sectional dimension (e.g., radius) than that of the enlarged aperture54. The tool60spins the plug58about a longitudinal axis62of the plug58, which axis62is substantially coaxial with the axis38of the enlarged aperture54. The tool60and/or a fixture (not shown) holding the component20subsequently move relative to one another such that the spinning plug58translates along the axis38,62into the enlarged aperture54. The spinning plug58may be pushed into the enlarged aperture54as shown byFIGS. 7 and 8. Alternatively, the spinning plug58may be pulled through the aperture54using other known friction plug welding systems.

Frictional contact between materials of the plug58and the flange28during the moving of the spinning plug58into the enlarged aperture54cause plug58and aperture54to join together as shown inFIG. 9. In this manner, the plug58is welded to the flange28and thereby fills the previously enlarged aperture54with friction plug welded material56; i.e., material of the welded plug58.

Typically, a friction plug welding process generates significantly less heat than other known welding processes such arc welding; e.g., tungsten inert gas (TIG) welding or electron beam welding. As a result, the material of the flange28may not require heat treatment after the welding step404. In addition, the heat generated during the welding step404may be maintained below a critical temperature of another (e.g., a composite) material configured with the component20. For example, where the liner30ofFIGS. 1 and 2is bonded to the base26via a composite material adhesive, the heat generated during the welding step404may be less than a temperature at which molecular bonds of the adhesive breakdown.

In step406, one or more portions64and66of the friction plug welded material56may be removed. For example, referring toFIG. 9, a tip portion64of the welded plug58may project axially out from one of the flange side surfaces32. A base portion66of the welded plug58may project axially out from another one of the flange side surfaces32. Each of these portions64and66of the welded plug58may be machined (e.g., cut off and/or ground down) so as to provide the flange28with smooth flange side surfaces32as shown inFIG. 10.

In step408, a new (e.g., repaired or reconfigured) fastener aperture36B is formed in the friction welded material56as shown inFIGS. 11 and 12. The new fastener aperture36B, for example, may be drilled or otherwise machined into the friction welded material56. The new fastener aperture36B ofFIGS. 11 and 12is configured with an axis that is substantially coaxial with the axis38of the damaged fastener aperture36A. Thus, the new fastener aperture36B replaces the damaged fastener aperture36A.

Depending on the specific damage to the flange28, the new fastener aperture36B may have a different (e.g., smaller) cross-sectional dimension and, thus, a different (e.g., smaller) cross-sectional area than the damaged fastener aperture36A. The new fastener aperture26B may also or alternatively have a different cross-sectional shape than the damaged fastener aperture36A. The axes of the fastener aperture36A and/or36B may be parallel to the centerline22, or alternatively angled relative to the centerline22.

In some embodiments, the method400may be performed to repair a damaged portion of another member of a case structure other than the flange28as described above. In still other embodiments, the method400may be performed to repair a damaged portion in another turbine engine component other than a case structure; e.g., a stator vane, a rotor disk, a shaft, a mid-turbine frame, etc.

In some embodiments, the damaged portion of the component20may not have originally included an aperture. However, the method400may be performed to drill out a defect in the damaged portion of the component20and then plug that hole as described above. The plug may then be left solid, or drilled to provide a fastener aperture where one was not previously located. The defect may be a crack, a fracture, a porous region, a pitted region, a worn region, a corroded region and/or any other type of defective region.

In some embodiments, the component20may be heat treated after the friction plug welding step. This heat treatment may be performed before or after the formation of the new fastener aperture36B.

In some embodiments, the component20may be in an aero gas turbine engine.FIG. 13illustrates an exemplary embodiment of such a gas turbine engine70, which is configured as a geared turbofan gas turbine engine. This turbine engine70extends along an axis72(e.g., centerline22) between an upstream airflow inlet74and a downstream airflow exhaust76. The turbine engine70includes a fan section78, a compressor section79, a combustor section80and a turbine section81. The compressor section79includes a low pressure compressor (LPC) section79A and a high pressure compressor (HPC) section79B. The turbine section81includes a high pressure turbine (HPT) section81A and a low pressure turbine (LPT) section81B.

The engine sections78-81are arranged sequentially along the axis72within an engine housing84. This housing84includes an inner case86(e.g., a core case) and an outer case88(e.g., a fan case structure), which may include the component20. The inner case86may house one or more of the engine sections79-81; e.g., an engine core. The outer case88may house at least the fan section78.

Each of the engine sections78,79A,79B,81A and81B includes a respective rotor90-94. Each of these rotors90-94includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks. The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed, adhered and/or otherwise attached to the respective rotor disk(s).

The fan rotor90is connected to a gear train96, for example, through a fan shaft98. The gear train96and the LPC rotor91are connected to and driven by the LPT rotor94through a low speed shaft99. The HPC rotor92is connected to and driven by the HPT rotor93through a high speed shaft100. The shafts98-100are rotatably supported by a plurality of bearings102. Each of these bearings102is connected to the engine housing84by at least one stationary structure such as, for example, an annular support strut.

During operation, air enters the turbine engine70through the airflow inlet74. This air is directed through the fan section78and into a core gas path104and a bypass gas path106. The core gas path104extends sequentially through the engine sections79-81. The bypass gas path106extends away from the fan section78through a bypass duct, which circumscribes and bypasses the engine core. The air within the core gas path104may be referred to as “core air”. The air within the bypass gas path106may be referred to as “bypass air”.

The core air is compressed by the compressor rotors91and92and directed into a combustion chamber108of a combustor in the combustor section80. Fuel is injected into the combustion chamber108and mixed with the compressed core air to provide a fuel-air mixture. This fuel air mixture is ignited and combustion products thereof flow through and sequentially cause the turbine rotors93and94to rotate. The rotation of the turbine rotors93and94respectively drive rotation of the compressor rotors92and91and, thus, compression of the air received from a core airflow inlet. The rotation of the turbine rotor94also drives rotation of the fan rotor90, which propels bypass air through and out of the bypass gas path106. The propulsion of the bypass air may account for a majority of thrust generated by the turbine engine70, e.g., more than seventy-five percent (75%) of engine thrust. The turbine engine70of the present disclosure, however, is not limited to the foregoing exemplary thrust ratio.

The component20may be included in various aircraft and industrial turbine engines other than the one described above. The component20, for example, may be included in a geared turbine engine where a gear train connects one or more shafts to one or more rotors in a fan section, a compressor section and/or any other engine section. Alternatively, the component20may be included in a turbine engine configured without a gear train. The component20may be included in a geared or non-geared turbine engine configured with a single spool, with two spools (e.g., seeFIG. 13), or with more than two spools. The turbine engine70may be configured as a turbofan engine, a turbojet engine, a propfan engine, a pusher fan engine or any other type of turbine engine. The present disclosure therefore is not limited to any particular types or configurations of turbine engine, or to turbine engine applications as set forth above.