Patent Publication Number: US-8123463-B2

Title: Method and system for manufacturing a blade

Description:
BACKGROUND OF THE INVENTION 
     The field of this disclosure relates generally to blades and, more particularly, to a method and a system for manufacturing blades. 
     Many known gas turbine engine compressors include rotor blades that extend radially outwardly from a disk or spool to a blade tip to define an airflow path through the engine. In operation, air flowing through the engine imparts significant mechanical stresses (e.g., chordwise bending stresses) on the blades, causing the blades to crack or otherwise fail over time. As such, at least some known rotor blades are formed from plies of composite material that internally span the length of the blade to facilitate adding structural support and longevity to the blade. 
     At least some known compressor rotor blades have a larger cross-sectional area proximate the root of the blade to form a dovetail for coupling the blade to the disk or spool. To form the larger cross-sectional area, supplemental composite plies are often inserted near the root of the blade to spread apart the composite plies that span the blade. In many known rotor blades, the supplemental plies create zones of weakness throughout the dovetail, increasing the likelihood that the blade will fail under the thermal and/or mechanical stresses imparted on the blade during operation of the gas turbine engine. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one aspect, a method of manufacturing a blade is provided. The method includes providing a plurality of first plies, each of the first plies sized to extend substantially the length of a span of the blade and providing a plurality of second plies, each of the second plies sized to extend only partially the length of the span of the blade. The method also includes layering the plurality of first plies and the plurality of second plies in a mold such that the plurality of second plies is interspersed throughout the plurality of first plies to spread apart the plurality of first plies to facilitate increasing a cross-sectional area of the blade and bonding the plurality of first plies to the plurality of second plies to facilitate forming a structural core of the blade. 
     In another aspect, a system for manufacturing a blade is provided. The system includes a mold and a plurality of first plies, each of the first plies sized to extend substantially the length of a span of the blade. The system also includes a plurality of second plies, each of the second plies sized to extend only partially the length of the span of the blade, the plurality of first plies layered with the plurality of second plies in the mold such that the plurality of second plies is interspersed throughout the plurality of first plies to spread apart the plurality of first plies to facilitate increasing a cross-sectional area of the blade. 
     In another aspect, a blade is provided. The blade includes a plurality of first plies, each of the first plies sized to extend substantially the length of a span of the blade. The blade also includes a plurality of second plies, each of the second plies sized to extend only partially the length of the span of the blade, the plurality of first plies layered with the plurality of second plies such that the plurality of second plies is interspersed throughout the plurality of first plies to spread apart the plurality of first plies to facilitate increasing a cross-sectional area of the blade, the plurality of first plies bonded to the plurality of second plies. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a gas turbine engine; 
         FIG. 2  is a perspective view of a rotor blade for use with the gas turbine engine shown in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the blade shown in  FIG. 2 ; 
         FIG. 4  is a plan view of an exemplary ply for use in manufacturing the blade shown in  FIG. 3 ; 
         FIG. 5  is an enlarged cross-sectional view of a portion of the blade shown in  FIG. 3 ; and 
         FIG. 6  is an exploded view of a portion of the blade shown in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description illustrates exemplary methods and a system for manufacturing blades by way of example and not by way of limitation. The description enables one of ordinary skill in the art to make and use the disclosure, and the description describes several embodiments, adaptations, variations, alternatives, and uses of the disclosure, including what is presently believed to be the best mode of carrying out the disclosure. The disclosure is described herein as being applied to a preferred embodiment, namely, methods and a system for manufacturing blades. However, it is contemplated that this disclosure has general application to manufacturing components in a broad range of systems and in a variety of industrial and/or consumer applications. 
       FIG. 1  is a schematic illustration of a gas turbine engine  100  including a fan assembly  102 , a high pressure compressor  104 , and a combustor  106 . Engine  100  also includes a high pressure turbine  108  and a low pressure turbine  110 . In operation, air flows through fan assembly  102  and compressed air is supplied from fan assembly  102  to high pressure compressor  104 . The highly compressed air is delivered to combustor  106 . Airflow from combustor  106  drives rotating turbines  108  and  110  and exits gas turbine engine  100  through an exhaust system  118 . 
       FIG. 2  is a perspective view of an exemplary rotor blade  200  for use with gas turbine engine  100  (shown in  FIG. 1 ). In one embodiment, a plurality of rotor blades  200  form a high pressure compressor stage (not shown) of gas turbine engine  100 . Each rotor blade  200  includes an airfoil  202  and an integral dovetail  204  for mounting airfoil  202  to a rotor disk (not shown). In one embodiment, blades  200  may extend radially outwardly from the disk such that a plurality of blades  200  form a blisk (not shown). 
     Airfoil  202  includes a first contoured sidewall  206  and a second contoured sidewall  208 . First sidewall  206  is convex and defines a suction side of airfoil  202 , and second sidewall  208  is concave and defines a pressure side of airfoil  202 . Sidewalls  206  and  208  are joined at a leading edge  210  and at an axially-spaced trailing edge  212 . A chord  214  of airfoil  202  includes a chord length  216  that represents the distance from leading edge  210  to trailing edge  212 . More specifically, airfoil trailing edge  212  is spaced chordwise and downstream from airfoil leading edge  210 . First and second sidewalls  206  and  208  extend radially outward in a span  218  from a root  220  to a tip  222 . In the exemplary embodiment, blade  200  has a greater cross-sectional area CC proximate root  220  than proximate tip  222  to facilitate forming dovetail  224  for coupling blade  200  to the disk. 
       FIG. 3  is a cross-sectional view of blade  200  proximate dovetail  224  during a manufacturing process of blade  200 . In the exemplary embodiment, blade  200  is constructed by stacking plies  302  of composite material in a mold  304  and heating mold  304  (e.g., using a curing process) to form a structural core  306  of blade  200 . Mold  304  is at least partially formed in the shape of blade  200 . In the exemplary embodiment, mold  304  has two halves, namely a pressure half  308  and a suction half  310 . Pressure half  308  and suction half  310  extend from a mold base portion  312  to a mold tip portion (not shown). An axis X runs through mold from base portion  312  to the tip portion. Pressure half  308  and suction half  310  are generally convex and may be coupled together to form mold  304 . Mold  304  includes a hollow cavity (not shown) that is sized to accommodate a stack  314  of plies  302  therein. 
     In the exemplary embodiment, blade  200  is formed by initially layering plies  302  atop one another upwardly from pressure half  308  (hereinafter referred to as stacking plies  302  in an “upward direction  309 ”) and coupling suction half  310  with pressure half  308  to at least partially encase stack  314  within the cavity of mold  304 . Alternatively, stack  314  may be formed by layering plies  302  in any direction relative to mold  304  that enables blade  200  to function as described herein, such as, for example, by layering plies  302  atop one another upwardly from suction half  310 . After encasing stack  314  within mold  304 , mold  304  is subjected to a heating process that facilitates solidifying stack  314  into a structural core  306 . After structural core  306  has been formed, structural core  306  is removed from mold  304  and is machined along a dovetail form  316  (e.g., using a grinding process) to create blade root  220  (shown in  FIG. 2 ) and dovetail  224  (shown in  FIG. 2 ). 
     Stack  314  includes plies  302  that extend substantially the length of span  218  (shown in  FIG. 2 ) (i.e., extend from blade root  220  to blade tip  222  after structural core  306  has been machined at dovetail form  316 ) (hereinafter referred to as “structural plies  318 ”). Stack  314  also includes plies  302  that extend only partially the length of span  218  (i.e., extend only a portion of span  218  from blade root  220  after structural core  306  has been machined at dovetail form  316 ) (hereinafter referred to as “insert plies  320 ”). Insert plies  320  are layered in stack  314  to facilitate spreading structural plies  318  apart from one another proximate root  220  to facilitate forming dovetail  224 . In one embodiment, insert plies  320  may be fabricated from a different material (e.g., a different composite material) than the material used to fabricate structural plies  318 . Insert plies  320  are layered in stack  314  in bunches (hereinafter referred to as “insert packs  322 ”). In one embodiment, each insert pack  322  may include ten insert plies  320 , for example. In another embodiment, insert pack  322  may include only one insert ply  320 . Alternatively, insert pack  322  may include any number of insert plies  320  that enables blade  200  to function as described herein. 
       FIG. 4  is a plan view of an exemplary ply  302  (shown in  FIG. 3 ). In the exemplary embodiment, ply  302  includes an arrangement  400  of composite fibers  402  (e.g., carbon fibers, ceramic matrix fibers, etc.). In one embodiment, composite fibers  402  are oriented in a direction relative to an axis Y of ply  302  (hereinafter referred to as a “unidirectional fiber orientation μ”). In another embodiment, arrangement  400  may include composite fibers that are woven together (i.e., oriented in different directions relative to axis Y). In the exemplary embodiment, arrangement  400  is impregnated with a resin material (not shown) such that, during the heating process, the resin material flows between plies  302  of stack  314  (shown in  FIG. 3 ) to facilitate solidifying structural core  306 . As used herein, the term “ply” refers to a segment of material having any contour and is not limited to substantially planar material segments as described herein. 
       FIG. 5  is an enlarged cross-sectional view of a portion  500  of stack  314  (shown in  FIG. 3 ) taken along area  55 . Each insert pack  322  (shown in  FIG. 3 ) is formed with a tapered tip  501  that creates a divergence region  502  between adjacent structural plies  318  to facilitate reducing a formation of resin pockets  504  between insert pack  322  and adjacent structural plies  318  during the heating process. Tapered tip  501  is formed by staggering inner ends  506  of insert plies  320  as insert plies  320  are layered in stack  314 . In the exemplary embodiment, tapered tip  501  has a top insert ply  508 , a bottom insert ply  510 , and at least one middle insert ply  512  positioned between top insert ply  508  and bottom insert ply  510 . Bottom insert ply  510  extends into mold  304  a distance A from mold base portion  312 , middle insert ply  512  extends into mold  304  a distance B from mold base portion  312 , and top insert ply  508  extends into mold  304  a distance C from mold base portion  312 . In the exemplary embodiment, distance B is greater than distance A and distance C, such that middle insert ply  512  extends further from mold base portion  312  than top insert ply  508  and bottom insert ply  510 . In another embodiment, distance A is greater than distance B, and distance B is greater than distance C, such that bottom insert ply  510  extends further from mold base portion  312  than middle insert ply  512 , and middle insert ply  512  extends further from mold base portion  312  than top insert ply  508 . Alternatively, distance C is greater than distance B, and distance B is greater than distance A, such that top insert ply  508  extends further from mold base portion  312  than middle insert ply  512 , and middle insert ply  512  extends a distance further from mold base portion  312  than bottom insert ply  510 . 
     Each structural ply  318  has a thickness TT, and each insert ply  320  has a thickness T. In the exemplary embodiment, thickness TT is greater than thickness T to facilitate reducing a formation of resin pockets  504  during the heating process. In one embodiment, thickness TT is twice as thick as thickness T. For example, thickness TT may be approximately 0.01 inches, and thickness T may be approximately 0.005 inches. 
       FIG. 6  is an exploded view of a portion  600  of stack  314  (shown in  FIG. 3 ). In the exemplary embodiment, each ply  302  (shown in  FIG. 3 ) is layered in stack  314  such that unidirectional fiber orientation μ is angled relative to axis X of mold  304  (shown in  FIG. 3 ). Alternatively, at least one ply  302  may be layered in stack  314  such that unidirectional fiber orientation μ is parallel to axis X of mold  304 . 
     To form stack  314 , structural plies  318  (shown in  FIG. 3 ) are layered in upward direction  309  in a predetermined directional sequence (hereinafter referred to as the “structural ply stacking sequence  602 ”). In the exemplary embodiment, structural ply stacking sequence  602  is repeated throughout stack  314 . Alternatively, structural ply stacking sequence  602  may vary throughout stack  314 . A set  604  of structural plies  318  forms structural ply stacking sequence  602 . Set  604  may include any number of structural plies  318  that enables blade  200  to function as described herein. In the exemplary embodiment, set  604  includes a first structural ply  606 , a second structural ply  608 , a third structural ply  610 , and a fourth structural ply  612 , for example. First structural ply  606  is layered in stack  314  such that unidirectional orientation μ is positioned relative to axis X at an angle α. Second structural ply  608  is layered in stack  314  such that unidirectional orientation μ is positioned relative to axis X at an angle β. Third structural ply  610  is layered in stack  314  such that unidirectional orientation t is positioned relative to axis X at an angle ⊖. Fourth structural ply  612  is layered in stack  314  such that unidirectional orientation μ is positioned relative to axis X at an angle λ. Angles α, β, ⊖, and λ may constitute any angular orientation that enables blade  200  to function as described herein. Angles α, β, ⊖, and λ are different than one another in the exemplary embodiment. Alternatively, two or more of angles α, β, ⊖, and λ are the same. 
     To form stack  314 , insert plies  320  (shown in  FIG. 3 ) are also layered in upward direction  309  in a predetermined directional sequence (hereinafter referred to as the “insert ply stacking sequence  614 ”). In the exemplary embodiment, insert ply stacking sequence  614  is repeated throughout stack  314 . Alternatively, insert ply stacking sequence  614  may vary throughout stack  314 . A set  616  of insert plies  320  forms insert ply stacking sequence  614 . Set  616  may include any number of insert plies  320  that enables blade  200  to function as described herein. In the exemplary embodiment, set  616  includes a first insert ply  618 , a second insert ply  620 , a third insert ply  622 , and a fourth insert ply  624 , for example. First insert ply  618  is layered in stack  314  such that unidirectional orientation μ is positioned relative to axis X at an angle ε. Second insert ply  620  is layered in stack  314  such that unidirectional orientation μ is positioned relative to axis X at an angle ρ. Third insert ply  622  is layered in stack  314  such that unidirectional orientation μ is positioned relative to axis X at an angle τ. Fourth insert ply  624  is layered in stack  314  such that unidirectional orientation μ is positioned relative to axis X at an angle ψ. Angles α, β, ⊖, and λ may be any angular orientation that enables blade  200  to function as described herein. In the exemplary embodiment, angles ε, ρ, τ, and ψ are different than one another. Alternatively, two or more of angles ε, ρ, τ, and ψ are the same. In the exemplary embodiment, insert ply stacking sequence  614  is different than structural ply stacking sequence  602 . In one embodiment, at least one of the following is true: angle α is different than angle ε; angle β is different than angle ρ; angle ⊖ is different than angle τ; and angle λ is different than angle ψ. 
     The methods and systems described herein enable a blade to be manufactured in a manner that facilitates increasing a load carrying capacity of the blade. The methods and systems described herein further enable a blade to be manufactured to have a more uniform core structure that facilitates reducing the likelihood that the blade will crack or otherwise fail under thermal or mechanical stress applications. The methods and systems described herein further facilitate increasing a reliability of the blade and thus extending a useful life of the blade, while also reducing a cost associated with manufacturing the blade. 
     Exemplary embodiments of methods and systems for manufacturing blades are described above in detail. The methods and systems for manufacturing blades are not limited to the specific embodiments described herein, but rather, components of the methods and systems may be utilized independently and separately from other components described herein. For example, the methods and systems described herein may have other industrial and/or consumer applications and are not limited to practice with rotor blades as described herein. Rather, the present invention can be implemented and utilized in connection with many other industries. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.