Patent Publication Number: US-9840926-B2

Title: Abrasive flow media fixture with end contour

Description:
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.