# Patent

## Title
Abrasive flow media fixture with end contour

## Abstract

A fixture assembly includes an inner diameter wall displaced from a main body by a first end wall with a convex surface and a second end wall with a concave surface. A method of machining a gas turbine engine component with an Abrasive Flow Media (AFM) process includes restricting a flow of media adjacent to an outer sidewall of an outer airfoil to be generally equal between each of a multiple of airfoils of the component.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to PCT Patent Application No. PCT/US14/045758 filed Jul. 8, 2014, which claims priority to U.S. Provisional Patent Application No. 61/844,680 filed Jul. 10, 2013.


BACKGROUND
The present disclosure relates to a fixture assembly and, more particularly, to a gas turbine engine airfoil fixture.
Gas turbine engines, such as those that power modern commercial and military aircraft, generally include a compressor section to pressurize an airflow, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases.
The compressor section includes a case circumscribing an engine axis and axially alternating arrays of stationary vanes and rotatable blades. Each vane array may be constructed of multiple vane clusters distributed circumferentially about the interior of the case with each cluster supported by the case. Some vane arrays include clusters of cantilevered vanes.
Precision engineered parts such as gas turbine components may be manufactured by direct metal laser sintering (DMLS) which is an additive metal fabrication technology sometimes also referred to by the terms selective laser sintering (SLS) or selective laser melting (SLM). DMLS components such as stators and rotor blades are typically final machined with an Abrasive Flow Media (AFM) process. The AFM process generally utilizes a putty packed with abrasive particles that is forced under high pressures around the surfaces of the component. Although effective, the AFM process may result in some differences in the desired surface state over the entirety of each component.
SUMMARY
A fixture assembly for an Abrasive Flow Media (AFM) process is provided according to one disclosed non-limiting embodiment of the present disclosure. This fixture assembly includes a main body and an inner diameter wall displaced from the main body by a first end wall with a convex surface and a second end wall with a concave surface.
In a further embodiment of the present disclosure, the inner diameter wall is arcuate.
In a further embodiment of any of the foregoing embodiments of the present disclosure, a lock plate is included that is mountable to the main body to retain a component between the first end wall and the second end wall.
In a further embodiment of any of the foregoing embodiments of the present disclosure, the component includes a multiple of airfoils.
In a further embodiment of any of the foregoing embodiments of the present disclosure, one of the multiple of airfoils includes a concave sidewall which faces the convex surface.
In a further embodiment of any of the foregoing embodiments of the present disclosure, the concave sidewall which faces the convex surface is displaced by a predetermined distance that is about equal to a distance between each of the multiple of airfoils.
In a further embodiment of any of the foregoing embodiments of the present disclosure, one of the multiple of airfoils includes a convex sidewall which faces the concave surface.
In a further embodiment of any of the foregoing embodiments of the present disclosure, the convex sidewall that faces the concave surface is displaced by a predetermined distance that is about equal to a distance between each of the multiple of airfoils.
In a further embodiment of any of the foregoing embodiments of the present disclosure, a first of the multiple of airfoils includes a concave sidewall that faces the convex surface and a second of the multiple of airfoils includes a convex sidewall that faces the concave surface.
In a further embodiment of any of the foregoing embodiments of the present disclosure, the concave sidewall which faces the convex surface and the convex sidewall which faces the concave surface is displaced by a predetermined distance that is about equal to a distance between each of the multiple of airfoils.
In a further embodiment of any of the foregoing embodiments of the present disclosure, the inner diameter wall is defined a predetermined distance from a tip of a component retained by the main body.
In a further embodiment of any of the foregoing embodiments of the present disclosure, the predetermined distance is about equal to a distance between each of a multiple of airfoils of the component.
In a further embodiment of any of the foregoing embodiments of the present disclosure, the component is a vane cluster.
A method of machining a gas turbine engine component with an Abrasive Flow Media (AFM) process is provided according to another disclosed non-limiting embodiment of the present disclosure. This method includes restricting a flow of media adjacent to an outer sidewall of an outer airfoil to be generally equal between each of a multiple of airfoils of the component.
In a further embodiment of any of the foregoing embodiments of the present disclosure, the method includes utilizing an Abrasive Flow Media (AFM) process for machining of the gas turbine engine component.
In a further embodiment of any of the foregoing embodiments of the present disclosure, the method includes locating a convex surface of a fixture adjacent to a concave sidewall of the outer airfoil.
In a further embodiment of any of the foregoing embodiments of the present disclosure, the method includes locating a concave surface of a fixture adjacent to a convex sidewall of the outer airfoil.
In a further embodiment of any of the foregoing embodiments of the present disclosure, the method includes: locating a convex surface of a fixture adjacent to a concave sidewall of a first outer airfoil of the component; and locating a concave surface of the fixture adjacent to a convex sidewall of a second outer airfoil of the component.
The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting.



BRIEF DESCRIPTION OF THE DRAWINGS
Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiments. The drawings that accompany the detailed description can be briefly described as follows:
FIG. 1 is a schematic cross-section of an example gas turbine engine;
FIG. 2 is a schematic cross-section of another example gas turbine engine;
FIG. 3 is a schematic expanded cross-section of a portion of an engine case with a multiple of cantilevered mounted stator vane airfoils of a multiple of vane clusters;
FIG. 4 is a front view of a vane array with a multiple of cantilevered mounted stator vane airfoils of a multiple of vane clusters;
FIG. 5 is a perspective partially exploded view of a vane cluster;
FIG. 6 is a perspective view of an abrasive flow media process fixture assembly;
FIG. 7 is a sectional view of an abrasive flow media process housing which contains a multiple of fixture assemblies;
FIG. 8 is an expanded view of a portion of the fixture assembly of FIG. 6; and
FIG. 9 is an expanded view of a portion of the fixture assembly of FIG. 6 at an end opposite the FIG. 8 end.



DETAILED DESCRIPTION
FIG. 1 schematically illustrates a gas turbine engine 20. The gas turbine engine 20 is disclosed herein as a two-spool turbo fan that generally incorporates a fan section 22, a compressor section 24, a combustor section 26 and a turbine section 28. Referring to FIG. 2, alternative engine architectures 10 might include an augmentor section 12 and exhaust duct section 14 among other systems or features. Referring again to FIG. 1, the fan section 22 drives air along a bypass flowpath while the compressor section 24 drives air along a core flowpath for compression and communication into the combustor section 26 then expansion through the turbine section 28. Although depicted as a turbofan in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engine architecture such as turbojets, turboshafts, and three-spool (plus fan) turbofans wherein an intermediate spool includes an intermediate pressure compressor (“IPC”) between a low pressure compressor (“LPC”) and a high pressure compressor (“HPC”), and an intermediate pressure turbine (“IPT”) between a high pressure turbine (“HPT”) and a low pressure turbine (“LPT”).
The engine 20 generally includes a low spool 30 and a high spool 32 mounted for rotation about an engine central longitudinal axis X relative to an engine static structure 36 via several bearing structures 38. The low spool 30 generally includes an inner shaft 40 that interconnects a fan 42, a low pressure compressor (“LPC”) 44 and a low pressure turbine (“LPT”) 46. The inner shaft 40 may drive the fan 42 directly or through a geared architecture 48 as illustrated in FIG. 1 to drive the fan 42 at a lower speed than the low spool 30. An exemplary reduction transmission is an epicyclic transmission, namely a planetary or star gear system.
The high spool 32 includes an outer shaft 50 that interconnects a high pressure compressor (“HPC”) 52 and a high pressure turbine (“HPT”) 54. A combustor 56 is arranged between the high pressure compressor 52 and the high pressure turbine 54. The inner shaft 40 and the outer shaft 50 are concentric and rotate about the engine central longitudinal axis X which is collinear with their longitudinal axes.
Core airflow is compressed by the LPC 44 then the HPC 52, mixed with the fuel and burned in the combustor 56, then expanded over the HPT 54 and the LPT 46. The turbines 46, 54 rotationally drive the respective low spool 30 and high spool 32 in response to the expansion. The main engine shafts 40, 50 are supported at a plurality of points by the bearing structures 38 within the static structure 36. It should be understood that various bearing structures 38 at various locations may alternatively or additionally be provided.
The HPC 52 includes a multiple of stages with alternate stationary vane arrays 60 and rotational rotor assemblies 62 along an airflow passage 64. Although the HPC 52 is illustrated in the disclosed non-limiting embodiment, other engine sections will also benefit herefrom. Moreover, although a particular number of stages are illustrated, it should be appreciated that any number of stages will benefit herefrom.
With reference to FIG. 3, each vane array 60 (also shown in FIG. 4) includes a multiple of cantilevered mounted stator vane airfoils 66 that extend in a cantilever manner from a platform 68 toward the engine central longitudinal axis X. The platform 68 is mounted to the engine static structure 36 such as an engine case 36-1 via, for example, segmented hooks or other interfaces. Each vane array 60 may be formed of a multiple of vane clusters 70 (see FIG. 5) each with a multiple of cantilevered mounted stator vane airfoils 66. It should be understood that various numbers of cantilevered mounted stator vane airfoils 66 and vane clusters 70 will benefit herefrom.
Each of the rotor assemblies 62 includes a multiple of blades 72 supported by a respective rotor hub 74. The platform 68 and airfoils 66 of the vane arrays 60 and a platform 76 that extends from each of the multiple of blades 72 generally bounds the airflow passage 64. The multiple of cantilevered mounted stator vane airfoils 66 extend in a cantilever manner from the engine case 36-1 such that the cantilevered mounted stator vane airfoils 66 extend toward the engine axis X to be disposed in close proximity to the hub 74. Provision for close clearances between the cantilevered mounted stator vane airfoils 66 and the rotor hub 74 increases engine efficiency.
With reference to FIG. 5, each cantilevered mounted stator vane airfoil 66 includes a first sidewall 86 that may be convex and defines a suction side, and a second sidewall 88 that may be concave and define a pressure side of the cantilevered mounted stator vane airfoils 66. Sidewalls 86, 88 are joined at a leading edge 96 and at an axially spaced trailing edge 98. More specifically, the airfoil trailing edge 98 is spaced chordwise and downstream from the airfoil leading edge 96. The sidewall 86 and the sidewall 88, respectively, extend longitudinally or radially outward in span from an (e.g., outer) airfoil root 90 to a (e.g., inner) tip 92. Each vane cluster 70 may be manufactured from a metallic alloy such as, but not limited to, titanium or a composite material.
In one disclosed non-limiting embodiment, the vane cluster 70 is manufactured by direct metal laser sintering (DMLS) which is an additive metal fabrication technology sometimes also referred to by the terms selective laser sintering (SLS) or selective laser melting (SLM). The DMLS manufactured vane cluster 70 components are then machined with, for example, an Abrasive Flow Media (AFM) process such as that of Micro Technica Technologies [http://www.micro-technica.de/abrasive_flow/Abrasive_Flow_Machining html]. It should be appreciated that although a vane cluster 70 is illustrated in the disclosed non-limiting embodiment, other components such as blades that are to be fine machined, other flow structures, or indeed any additively manufactured component with a complex geometry requiring a smooth surface will also benefit herefrom.
With reference to FIG. 6, each vane cluster 70 is mounted within a fixture assembly 100 for use with the example AFM process. Although a particular fixture configuration is illustrated it should be appreciated that other fixtures will benefit herefrom.
The fixture assembly 100 generally includes a frame 102 to which is attached a lock plate 104 that retains the vane cluster 70. The frame 102 includes an inner diameter wall 106 displaced from a main body 108 of the frame 102. The main body 108 is configured to receive the platform 68 generally as mounted to the engine static structure 36 and retained to the frame 102 by the lock plate 104 with fasteners 105. Furthermore, a multiple of fixture assemblies 100 may be assembled in a ring within a housing 101 (see FIG. 7) for use with the AFM process.
The inner diameter wall 106 is adjacent to the tip 92 of each of the airfoils 66 of the vane cluster 70. The inner diameter wall 106 is generally arcuate and displaced a predetermined distance from each tip 92 that, in the disclosed non-limiting embodiment, slows or essentially prevents flow of the abrasive media to assure even minimal abrasive wear on the tips 92. Edge radii of the tips 92, for example, are thereby maintained to desired specifications. In one disclosed non-limiting embodiment, the inner diameter wall 106 is spaced relatively close to each tip 92.
The inner diameter wall 106 is spaced from the main body 108 of the frame 102 by a first end wall 112 and a second end wall 114. The first end wall 112 is located adjacent to a second sidewall 88 that may be concave and define a pressure side of a first stator vane airfoil 66-1 (see FIG. 8). The second end wall 114 that may be convex is located adjacent to the first sidewall 86 and defines a suction side of another stator vane airfoil 66-2 that, in this disclosed non limiting embodiment is, for example, the sixteenth (16th) or last stator vane airfoil of the vane cluster 70 (see FIG. 9). It should be appreciate that the vane cluster 70 with any number of stator vane airfoils will benefit herefrom.
In the disclosed non-limiting embodiment, the first end wall 112 includes a convex surface 116 and the second end wall 114 includes a concave surface 118. That is, the convex surface 116 faces the concave surface of the second sidewall 88 and the concave surface 118 faces the convex surface of the first sidewall 86. Alternatively, the inner diameter wall 106 or the main body 108 may define separate airfoil shaped structures which imitate the shape of the each airfoil 66.
The convex surface 116 and the concave surface 118 are spaced a distance L from the respective stator vane airfoil 66-1, 66-2 that is equivalent to distance W. That is, the end walls 112, 114 essentially operate as additional sidewall surfaces for the respective outer stator vane airfoils 66-1, 66-2 to represent the adjacent airfoils of adjacent vane clusters 70 as assembled in the engine 20.
The end walls 112, 114 restrict the flow of the media of the example AFM process around the outer airfoils experience such that the outer stator vane airfoil 66-1, 66-2 experience the same flow as the other outer stator vane airfoil as compared to flat end walls which choke the media flow which may result in uneven wear.
The inner diameter wall 106 restricts the flow of the media of the example AFM process along the airfoil sidewalls 86, 88 and tips 92. Edge radii of the tips 92, for example, are thereby maintained to desired specifications.
The fixture assembly 100 masks the portions of the vane cluster 70 that do not require contact with the media of the example AFM process. The fixture assembly 100 may be manufactured of a glass-impregnated nylon in an additive manufacturing system to facilitate manufacture of the relatively complex three-dimensional geometry.
The use of the terms “a” and “an” and “the” and similar references in the context of description (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or specifically contradicted by context. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. It should be appreciated that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting.
Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.
It should be appreciated that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be appreciated that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.
Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.
The foregoing description is exemplary rather than defined by the features within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be appreciated that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.

## Claims

1. A fixture assembly for an Abrasive Flow Media process, the assembly comprising:
a main body;
an inner diameter wall displaced from said main body by a first end wall with a convex surface and a second end wall with a concave surface; and
a lock plate mountable to said main body to retain a component between said first end wall and said second end wall.

2. The assembly as recited in claim 1, wherein said inner diameter wall is arcuate.

3. The assembly as recited in claim 1, wherein said component includes a multiple of airfoils.

4. The assembly as recited in claim 3, wherein one said multiple of airfoils includes a concave sidewall which faces said convex surface.

5. The assembly as recited in claim 4, wherein said concave sidewall which faces said convex surface is displaced by a predetermined distance that is about equal to a distance between each of said multiple of airfoils.

6. The assembly as recited in claim 3, wherein one of said multiple of airfoils includes a convex sidewall which faces said concave surface.

7. The assembly as recited in claim 6, wherein said convex sidewall which faces said concave surface is displaced by a predetermined distance that is about equal to a distance between each of said multiple of airfoils.

8. The assembly as recited in claim 3, wherein a first of said multiple of airfoils includes a concave sidewall which faces said convex surface and a second of said multiple of airfoils includes a convex sidewall which faces said concave surface.

9. The assembly as recited in claim 4, wherein said concave sidewall which faces said convex surface and said convex sidewall which faces said concave surface is displaced by a predetermined distance that is about equal to a distance between each of said multiple of airfoils.

10. The assembly as recited in claim 9, wherein said inner diameter wall is defined a predetermined distance from a tip of a component retained by said main body.

11. The assembly as recited in claim 10, wherein said predetermined distance is about equal to a distance between each of a multiple of airfoils of the component.

12. The assembly as recited in claim 3, wherein said component is a vane cluster.

13. A method of machining a gas turbine engine component with an Abrasive Flow Media process, the method comprising:
restricting a flow of media adjacent to an outer sidewall of an outer airfoil to be generally equal between each of a multiple of airfoils of the component;
locating a convex surface of a fixture adjacent to a concave sidewall of a first outer airfoil of the component; and
locating a concave surface of the fixture adjacent to a convex sidewall of a second outer airfoil of the component,
wherein the outer airfoil is one of the first outer airfoil or the second outer airfoil.

14. The method as recited in claim 13, further comprising utilizing an Abrasive Flow Media process for machining of the gas turbine engine component.