U.S. patent application number 16/037917 was filed with the patent office on 2018-11-08 for open-cell reticulated foam.
The applicant listed for this patent is United Technologies Corporation. Invention is credited to Steven J. Bullied, Ryan B. Noraas.
Application Number | 20180318873 16/037917 |
Document ID | / |
Family ID | 55650018 |
Filed Date | 2018-11-08 |
United States Patent
Application |
20180318873 |
Kind Code |
A1 |
Noraas; Ryan B. ; et
al. |
November 8, 2018 |
OPEN-CELL RETICULATED FOAM
Abstract
A foam for use in a lost-foam casting process utilized in the
manufacture of a component for a gas turbine engine, the foam
having a void fraction less than or equal to ninety five percent,
is disclosed. The foam may include a first layer comprising polymer
foam having an open-cell structure and a void fraction greater than
ninety five percent. A second layer, comprising adhesive, may be
adhered to the first layer. A third layer comprising particulate
material may be adhered to the second layer.
Inventors: |
Noraas; Ryan B.; (Hartford,
CT) ; Bullied; Steven J.; (Pomfret Center,
CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
United Technologies Corporation |
Farmington |
CT |
US |
|
|
Family ID: |
55650018 |
Appl. No.: |
16/037917 |
Filed: |
July 17, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14617291 |
Feb 9, 2015 |
10035174 |
|
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16037917 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22C 7/023 20130101;
F01D 5/28 20130101; F05D 2220/36 20130101; Y02T 50/60 20130101;
F05D 2300/43 20130101; C08J 9/36 20130101; B05D 3/007 20130101;
F01D 5/288 20130101; B05D 1/24 20130101; F05D 2230/31 20130101;
F05D 2300/603 20130101; Y02T 50/673 20130101; B22C 9/046 20130101;
F05D 2240/303 20130101; F05D 2300/612 20130101; Y02T 50/672
20130101 |
International
Class: |
B05D 1/24 20060101
B05D001/24; F01D 5/28 20060101 F01D005/28; B05D 3/00 20060101
B05D003/00; B22C 7/02 20060101 B22C007/02; B22C 9/04 20060101
B22C009/04; C08J 9/36 20060101 C08J009/36 |
Claims
1. A foam for forming a gas turbine engine fan blade using a
lost-foam casting process, the foam having a void fraction less
than or equal to ninety five percent, comprising: a first layer,
the first layer comprising a polymer foam having an open-cell
structure and a void fraction greater than ninety five percent; a
second layer, the second layer comprising an adhesive adhered to
the first layer; and a third layer, the third layer comprising a
particulate material, the third layer adhered to the second
layer.
2. The modified foam according to claim 1, wherein the polymer foam
is selected from the group consisting of polyurethane polymer foam,
polyvinyl chloride polymer foam, polystyrene polymer foam,
polyimide polymer foam, silicone polymer foam, polyethylene polymer
foam, polyester polymer foam, polypropylene foam and combinations
thereof.
3. The foam according to claim 1, wherein the adhesive is an
adhesive polymer selected from the group consisting of acrylic
polymer, alkyd polymer, styrene acrylic polymer, styrene butadiene
polymer, vinyl acetate polymer, vinyl acetate homopolymer polymer,
vinyl acrylic polymer, vinyl maleate polymer, vinyl versatate
polymer, vinyl alcohol polymer, polyvinyl chloride polymer,
polyvinylpyrrolidone polymer, casein and combinations thereof.
4. The foam according to claim 1, wherein the particulate material
is selected from the group consisting of wax powder, wood flour,
polymer powder and combinations thereof.
5. The foam according to claim 4, wherein the wax powder is
selected from the group consisting of animal wax powder, vegetable
wax powder, mineral wax powder, petroleum wax powder and
combinations thereof.
6. The foam according to claim 4, wherein the polymer powder is
selected from the group consisting of polyurethane polymer powder,
polyvinyl chloride polymer powder, polystyrene polymer powder,
polyimide polymer powder, polyethylene polymer powder, polyester
polymer powder, polypropylene polymer powder and combinations
thereof.
7. A method of manufacturing foam for forming a gas turbine engine
fan blade using a lost-foam casting process, the foam having a void
fraction less than or equal to ninety five percent, comprising:
providing a polymer foam having an open-cell structure and a void
fraction greater than ninety five percent; coating the polymer foam
with an adhesive; and applying a particulate material to the
adhesive.
8. The method of manufacturing the foam according to claim 7,
wherein the polymer foam is selected from the group consisting of
polyurethane polymer foam, polyvinyl chloride polymer foam,
polystyrene polymer foam, polyimide polymer foam, silicone polymer
foam, polyethylene polymer foam, polyester polymer foam,
polypropylene foam and combinations thereof.
9. The method of manufacturing the foam according to claim 7,
wherein the adhesive comprises an adhesive polymer, the adhesive
polymer selected from the group consisting of acrylic polymer,
alkyd polymer, styrene acrylic polymer, styrene butadiene polymer,
vinyl acetate polymer, vinyl acetate homopolymer polymer, vinyl
acrylic polymer, vinyl maleate polymer, vinyl versatate polymer,
vinyl alcohol polymer, polyvinyl chloride polymer,
polyvinylpyrrolidone polymer, casein and combinations thereof.
10. The method of manufacturing the foam according to claim 7,
wherein the particulate material is selected from the group
consisting of wax powder, wood flour, polymer powder and
combinations thereof.
11. The method of manufacturing the foam according to claim 10,
wherein the wax powder is selected from the group consisting of
animal wax powder, vegetable wax powder, mineral wax powder,
petroleum wax powder and combinations thereof.
12. The method of manufacturing the foam according to claim 10,
wherein the polymer powder is selected from the group consisting of
polyurethane polymer powder, polyvinyl chloride polymer powder,
polystyrene polymer powder, polyimide polymer powder, polyethylene
polymer powder, polyester polymer powder, polypropylene polymer
powder and combinations thereof.
13. The method of manufacturing the foam according to claim 7,
wherein the coating the polymer foam with an adhesive step
comprises applying an emulsion to the polymer foam, the emulsion
comprising an adhesive polymer and solvent.
14. The method of manufacturing the foam according to claim 13,
further comprising removing excess solvent from the polymer foam
before applying a particulate material to the adhesive.
15. The method of manufacturing the foam according to claim 7,
wherein the polymer foam comprises ligaments positioned between
nodes, and further comprising heating the foam to a temperature
above the melting temperature of the particulate material, followed
by cooling the foam to a temperature below the melting temperature
of the particulate material to form a substantially continuous
coating of particulate material over the ligaments.
16. The method of manufacturing the foam according to claim 7,
wherein the applying a particulate material to the adhesive
includes passing the adhesive coated polymer foam through a
fluidized bed of particulate material.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/617,291 filed on Feb. 9, 2015, the entire
contents of which are incorporated herein by reference thereto.
FIELD OF THE DISCLOSURE
[0002] This disclosure generally relates to open-cell reticulated
foam and, more specifically, to open-cell reticulated foam for use
in the creation of gas turbine engine fan blades.
BACKGROUND OF THE DISCLOSURE
[0003] In order to increase operational efficiency, and thereby
decrease fuel consumption, designers of gas turbine engines
continually pursue ways to decrease component weight while
maintaining resilience necessary for the operation of such engine.
Fan blades are no exception.
[0004] One way gas turbine engine designers have utilized to reduce
fan blade weight is by employing an open-cell reticulated metal
foam core enveloped by an outer shell of a resilient second
material that forms the airfoil. In one design, the outer shell is
manufactured from a metal or metal alloy. In another design, the
outer shell is comprised of one or more layers of composite
material.
[0005] Such fan blade designs are not without complication. The
void fraction of the open-cell reticulated foam utilized to
manufacture such metal foam is commonly about ninety seven percent.
While not necessarily conclusive, data suggests that the ligaments
and nodes of metal foams created with the use of such high void
fraction open-cell reticulated foams lack the strength and
mechanical properties necessary for use in a fan blade.
Accordingly, a need exists for modified, open-cell reticulated
foams that can be used as a precursor to manufacture open-cell
reticulated metal foams for a gas turbine engine fan blade. This
disclosure is directed toward this end.
SUMMARY OF THE DISCLOSURE
[0006] In accordance with one embodiment of the present disclosure,
a foam for use in a lost-foam casting process, the foam having a
void fraction less than or equal to ninety five percent, is
disclosed. The foam may comprise a first layer made of polymer foam
having an open-cell structure and a void fraction greater than
ninety five percent. The foam may further include a second layer of
an adhesive adhered to the first layer. Finally, the foam may
include a third layer comprising a particulate material adhered to
the second layer.
[0007] In a refinement of the foam for use in a lost foam casting
process, the foam having a void fraction less than or equal to
ninety five percent, the polymer foam may be selected from the
group consisting of polyurethane polymer foam, polyvinyl chloride
polymer foam, polystyrene polymer foam, polyimide polymer foam,
silicone polymer foam, polyethylene polymer foam, polyester polymer
foam and combinations thereof.
[0008] In another refinement of the foam for use in a lost foam
casting process, the foam having a void fraction less than or equal
to ninety five percent, the adhesive may be an adhesive polymer
selected from the group consisting of acrylic polymer, alkyd
polymer, styrene acrylic polymer, styrene butadiene polymer, vinyl
acetate polymer, vinyl acetate homopolymer polymer, vinyl acrylic
polymer, vinyl maleate polymer, vinyl versatate polymer, vinyl
alcohol polymer, polyvinyl chloride polymer, polyvinylpyrrolidone
polymer, casein and combinations thereof.
[0009] In another refinement of the foam for use in a lost foam
casting process, the foam having a void fraction less than or equal
to ninety five percent, the particulate material may be selected
from the group consisting of wax powder, wood flour, polymer powder
and combinations thereof.
[0010] In another refinement of the foam for use in a lost foam
casting process, the foam having a void fraction less than or equal
to ninety five percent, the wax powder may be selected from the
group consisting of animal wax powder, vegetable wax powder,
mineral wax powder, petroleum wax powder and combinations
thereof.
[0011] In another refinement of the foam for use in a lost foam
casting process, the foam having a void fraction less than or equal
to ninety five percent, the polymer powder may be selected from the
group consisting of polyurethane polymer powder, polyvinyl chloride
polymer powder, polystyrene polymer powder, polyimide polymer
powder, polyethylene polymer powder, polyester polymer powder,
polypropylene polymer powder and combinations thereof.
[0012] In accordance with another embodiment of the present
disclosure, a method for manufacturing foam for use in a lost-foam
casting process, the foam having a void fraction less than or equal
to ninety five percent, is disclosed. The method may include
providing polymer foam having an open-cell structure and a void
fraction greater than ninety five percent. Then, the polymer foam
may be coated with an adhesive. Finally, particulate matter may be
applied to the adhesive.
[0013] In a refinement of the method for manufacturing the foam for
use in a lost-foam casting process, the foam having a void fraction
less than ninety five percent, the polymer foam may be selected
from the group consisting of polyurethane polymer foam, polyvinyl
chloride polymer foam, polystyrene polymer foam, polyimide polymer
foam, silicone polymer foam, polyethylene polymer foam, polyester
polymer foam and combinations thereof.
[0014] In another refinement of the method for manufacturing the
foam for use in a lost-foam casting process, the foam having a void
fraction less than ninety five percent, the adhesive may comprise
an adhesive polymer, and the adhesive polymer may be selected from
the group consisting of acrylic polymer, alkyd polymer, styrene
acrylic polymer, styrene butadiene polymer, vinyl acetate polymer,
vinyl acetate homopolymer polymer, vinyl acrylic polymer, vinyl
maleate polymer, vinyl versatate polymer, vinyl alcohol polymer,
polyvinyl chloride polymer, polyvinylpyrrolidone polymer, casein
and combinations thereof.
[0015] In another refinement of the method for manufacturing the
foam for use in a lost-foam casting process, the foam having a void
fraction less than ninety five percent, the particulate material
may be selected from the group consisting of wax powder, wood
flour, polymer powder and combinations thereof.
[0016] In another refinement of the method for manufacturing the
foam for use in a lost-foam casting process, the foam having a void
fraction less than ninety five percent, the wax powder may be
selected from the group consisting of animal wax powder, vegetable
wax powder, mineral wax powder, petroleum wax powder and
combinations thereof.
[0017] In another refinement of the method for manufacturing the
foam for use in a lost-foam casting process, the foam having a void
fraction less than ninety five percent, the polymer powder may be
selected from the group consisting of polyurethane polymer powder,
polyvinyl chloride polymer powder, polystyrene polymer powder,
polyimide polymer powder, polyethylene polymer powder, polyester
polymer powder, polypropylene polymer powder and combinations
thereof.
[0018] In another refinement of the method for manufacturing the
foam for use in a lost-foam casting process, the foam having a void
fraction less than ninety five percent, the coating the polymer
foam with an adhesive step may comprise applying an emulsion to the
polymer foam, and the emulsion may comprise an adhesive polymer and
solvent.
[0019] In another refinement of the method for manufacturing the
foam for use in a lost-foam casting process, the foam having a void
fraction less than ninety five percent, the method may further
include the process of removing excess solvent from the polymer
foam before applying a particulate material to the adhesive.
[0020] In another refinement of the method for manufacturing the
foam for use in a lost-foam casting process, the foam having a void
fraction less than ninety five percent, the method may further
include wherein the polymer foam comprises ligaments positioned
between nodes, and further comprising heating the foam to a
temperature above the melting temperature of the particulate
material, followed by cooling the foam to a temperature below the
melting temperature of the particulate material to form a
substantially continuous coating of particulate material over the
ligaments.
[0021] In another refinement of the method for manufacturing the
foam for use in a lost-foam casting process, the foam having a void
fraction less than ninety five percent, the applying a particulate
material to the adhesive may include passing the adhesive coated
polymer foam through a fluidized bed of particulate material.
[0022] In accordance with another embodiment of the present
disclosure, a method for manufacturing a fan blade for a gas
turbine engine is disclosed. The method may include, providing
polymer foam having an open-cell structure and a void fraction
greater than ninety five percent, followed by coating the polymer
foam with an adhesive to create adhesive coated foam. In a next
step, a particulate material may be applied to the adhesive coated
foam to make a modified foam having a void fraction less than or
equal to ninety five percent. Then, the modified foam having a void
fraction less than or equal to ninety five percent may be covered
with a refractory material, and then this refractory material may
be cured until it hardens to form an investment. Next, the
investment casting may be heated to a temperature above the boiling
point of the modified foam having avoid fraction less than or equal
to ninety five percent to form a negative of modified foam. Then,
molten metal or metal alloy may be added to the negative, and the
negative may be cooled to a temperature below the melting
temperature of the metal or metal alloy to form a positive of the
modified foam. In a next step, the refractory material may be
removed to form an open-cell metal foam having a void fraction less
than or equal to ninety five percent. Finally, the open cell metal
foam having a void fraction less than or equal to ninety five
percent may be enveloped with an outer shell of first material, the
outer shell having the shape of an airfoil, to form a fan blade for
a gas turbine engine.
[0023] In a refinement of the method for manufacturing the fan
blade for a gas turbine engine, the polymer foam may be
polyurethane polymer foam, the adhesive may be vinyl acetate, the
particulate material may be polyethylene polymer powder and the
metal or metal alloy may be aluminum.
[0024] In another refinement of the method for manufacturing the
fan blade for a gas turbine engine, the outer shell of a first
material may be made of a metal or metal alloy selected from the
group consisting of aluminum, titanium and nickel, aluminum alloys,
steel, nickel alloys and titanium alloys.
[0025] In another refinement of the method for manufacturing the
fan blade for a gas turbine engine, the outer shell of a first
material may be made of a composite material, and the composite
material may be made fiber embedded in resin.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a side, partially cross-sectional view of a gas
turbine engine constructed in accordance with the present
disclosure.
[0027] FIG. 2 is a perspective view of an exemplary gas turbine
engine fan blade assembly that may be used in conjunction with the
gas turbine engine of FIG. 1.
[0028] FIG. 3 is a perspective view of an exemplary fan blade that
may be used in conjunction with the fan blade assembly of FIG.
2.
[0029] FIG. 4 is a cross-sectional view of the exemplary fan blade
that may be used in conjunction with the fan blade assembly of FIG.
2 taken along line 3-3 of FIG. 3.
[0030] FIG. 5 is a schematic illustration depicting open-cell
polymer foam for use in the manufacture of open-cell reticulated
metal foam, the open-celled reticulated metal foam able to be used
in the manufacture of the exemplary fan blade depicted in FIGS.
3-4.
[0031] FIGS. 6(a-b) are schematic illustrations depicting two
modified, open-cell polymer foams for use in the manufacture of
open-cell reticulated metal foam, the open-cell reticulated metal
foam able to be used in the manufacture of the exemplary fan blade
depicted in FIGS. 3-4.
[0032] FIG. 7 is a flowchart depicting an exemplary method for
preparing a modified, open-cell reticulated foam for use in the
manufacture of an open-cell reticulated metal foam, the open-cell
reticulated metal foam able to be used in the manufacture of the
exemplary fan blade depicted in FIGS. 3-4.
[0033] FIG. 8 is a flowchart depicting an exemplary method for
preparing the exemplary fan blade depicted in FIGS. 3-4 utilizing
the open-cell polymer foams of FIGS. 5-6 in a lost-foam casting
process.
[0034] These and other aspects and features of the present
disclosure will be more readily understood when read in conjunction
with the accompanying drawings.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0035] Referring now to the drawings, and with specific reference
to FIG. 1, a gas turbine engine is shown and generally referred to
be reference numeral 20. The gas turbine engine 20 disclosed herein
as a two-spool turbofan that generally incorporates a fan section
22, a compressor section 24, a combustor section 26 and a turbine
section 28. Alternative engines might include an augmentor section
(not shown) among other systems or features. The fan section 22
drives air along a bypass flowpath B, while the compressor section
24 drives air along a core flowpath C for compression and
communication into the combustor section 26. As will be described
in further detail herein, in the combustion section 26, the
compressor air is mixed with fuel and ignited, with the resulting
combustion gases then expanding in turbine section 28. Although
depicted as a turbofan gas turbine engine 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 engines
including, but not limited to, three-spool architectures as
well.
[0036] The engine 20 generally includes a low speed spool 30 and a
high speed spool 32 mounted for rotation about an engine central
longitudinal axis A relative to an engine static structure 36 via
several bearing systems 38. It should be understood that various
bearing systems 38 at various locations may alternatively or
additionally be provided.
[0037] The low speed spool 30 generally includes an inner shaft 40
that interconnects a fan blade assembly 42, a low pressure (or
first) compressor section 44 and a low pressure (or first) turbine
section 46. The inner shaft 40 is connected to the fan blade
assembly 42 through a geared architecture 48 to drive the fan
assembly 42 at a lower speed than the low speed spool 30. The high
speed spool 32 includes an outer shaft 50 that interconnects a high
pressure (or second) compressor section 52 and high pressure (or
second) turbine section 54. The outer shaft 50 is typically
concentric with and radially outward from the inner shaft 50. A
combustor 56 is arranged between the high pressure compressor 52
and the high pressure turbine 54. A mid-turbine frame 57 of the
engine static structure 36 is arranged generally between the high
pressure turbine 54 and the low pressure turbine 46. The
mid-turbine frame 57 supports one or more bearing systems 38 in the
turbine section 28. The inner shaft 40 and the outer shaft 50 are
concentric and rotate via bearing systems 38 about the engine
central longitudinal axis A, which is collinear with their
longitudinal axes. As used herein, a "high pressure" compressor or
turbine experiences a higher pressure than a corresponding "low
pressure" compressor or turbine.
[0038] The core airflow C is compressed first by the low pressure
compressor 44, and then by the high pressure compressor 52, before
being mixed and burned with fuel in the combustor 56, and lastly
expanded over the high pressure turbine 54 and low pressure turbine
46. The mid-turbine frame 57 includes airfoils 59 which are in the
core airflow path. The turbines 46, 54 rotationally drive the
respective low speed spool 30 and high speed spool 32 in response
to the expansion.
[0039] The engine 20 in one example is a high-bypass geared
aircraft engine. In a high-bypass engine a greater volume of air
moves along a bypass flowpath B than through core airflow C. The
ratio of the mass of air moving through bypass flowpath B to core
airflow C is known as the bypass ratio. In a further example, the
engine 20 bypass ratio is greater than about six (6), with an
example embodiment being greater than ten (10), the geared
architecture 48 is an epicyclic gear train, such as a star gear
system or other gear system, with a gear reduction ratio of greater
than about 2.3 and the low pressure turbine 46 has a pressure ratio
that is greater than about 5. In one disclosed embodiment, the
engine 20 bypass ratio is greater than about ten (10:1), the fan
diameter is significantly larger than that of the low pressure
compressor 44, and the low pressure turbine 46 has a pressure ratio
that is greater than about 5:1. Low pressure turbine 46 pressure
ratio is pressure measured prior to inlet of low pressure turbine
46 as related to the pressure at the outlet of the low pressure
turbine 46 prior to an exhaust nozzle. It should be understood,
however, that the above parameters are only exemplary of one
embodiment of a geared architecture engine and that the present
invention is applicable to other gas turbine engines including
direct drive turbofans.
[0040] Referring to FIGS. 2 and 3, a fan blade 60 of the fan blade
assembly 42 may include a root 62 supporting a platform 64. An
airfoil 66 may extend from the platform 64 to a tip 68. The airfoil
66 includes spaced apart leading and trailing edges 70, 72.
Pressure and suction sides 74, 76 adjoin the leading and trailing
edges 70, 72 to provide a fan blade contour 78. In certain
embodiments the fan blade includes a leading edge sheath 80. The
sheath 80 is secured to the fan blade 60 over the edge 82. In one
example, the sheath 80 is constructed from titanium. In another
example, the sheath 80 is made from titanium alloy. It should be
understood that other metals or materials may be used for sheath
80.
[0041] Now with reference to FIGS. 3-4, in one aspect of the
present disclosure, the fan blade 60 may include a core 84 of
open-cell reticulated metal foam enveloped by an outer shell 86 of
a first material. Although other configurations are possible, in
one embodiment the core 84 may extend from the about the tip 68 to
about the root 62. Similarly, the core 84 may extend from about the
leading edge 70 to about the trailing edge 72. Furthermore, in an
additional embodiment, the fan blade may include a second core (not
shown) being made of the first material surrounded by the shell
86.
[0042] The open-cell reticulated metal foam of the core 84 may be
made of a metal or a metal alloy. Although other metals are
certainly possible, some metals from which the open-cell
reticulated metal foam core 84 may be made consists of aluminum,
titanium, nickel, copper, lead, molybdenum, tin, zinc and
combinations thereof. Some metal alloys from which open-cell metal
foam of the core 84 may be made includes aluminum alloy, nickel
alloy, titanium alloy, steel and combinations thereof. Examples of
metal alloys from which the core 84 may be selected includes
aluminum alloys, steel, nickel alloys and titanium alloys, such as
series 2000, 6000 or 7000 aluminum, 300 and 400 series stainless
steels, precipitation hardenable stainless steels, Ti-6Al-4V,
Ti-6Al-2Sn-4Zr-2Mo, WASPALOY.RTM., INCONEL 718.RTM., INCONEL
718+.RTM., INCONEL 939.RTM. or HAYNES 282.RTM.. Other metal alloys
are certainly possible.
[0043] In one design, the first material comprising the outer shell
86 may be a metal or a metal alloy. While the following list is not
meant to be exhaustive, the metal from which outer shell 86 may be
made includes, but is not limited to, aluminum, titanium and
nickel. Some examples of metal alloys from which the outer shell 86
may be selected includes aluminum alloys, steel, nickel alloys and
titanium alloys, such as series 2000, 6000 or 7000 aluminum, 300
and 400 series stainless steels, precipitation hardenable stainless
steels, Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo, WASPALOY.RTM., INCONEL
718.RTM., INCONEL 718+.RTM., INCONEL 939.RTM. or HAYNES
282.RTM..
[0044] In another design, the first material comprising the outer
shell 86 may be a composite material. Such composite material may
be made of fiber embedded in resin. Some examples of the fibers
from which the composite material may be made include,
carbon-fiber, poly(p-phenylene-2,6-benzobisoxazole) fiber, mullite
fiber, alumina fiber, silicon nitride fiber, silicon carbide fiber,
boron fiber, boron nitride fiber, boron carbide fiber, glass fiber,
titanium diboride fiber, yttria stabilized zirconium fiber and
combinations thereof. Other fibers are certainly possible.
[0045] The resin of such composite material may be a thermoset
resin or a thermoplastic resin. Examples of resins from which the
composite material may be made includes, but is not limited to,
polyester, thermoset urethane, cyanate ester, vinyl ester,
polyimide, bisphenol A epoxy, bisphenol F epoxy, novolac epoxy,
glycidyl epoxy, cycloaliphatic epoxy, glycidylamine epoxy,
melamine, phenol formaldehyde, polyhexahydrotriazine, low density
polyethylene, medium density polyethylene, high density
polyethylene, ultra-high molecular weight polyethylene, polyvinyl
chloride, polyethylene terephthalate, vinyl, polypropylene,
poly(methyl methacrylate), nylon, polybenzimidazole, polystyrene,
polytetrafluroethylene, polyetherimide, polyether ketone, polyether
ether ketone, acrylonitrile butadiene styrene, styrene
acrylonitrile, acrylonitrile styrene acrylate, polyamide, polyaryl
ether ketone, polycarbonate, polyoxymethylene, polyphenylene ether,
polyphenylene sulfide, polysulfone, polybutylene terephthalate and
combinations thereof.
[0046] Now with reference to FIGS. 5-6(a-b), foam for use in a
lost-foam casting process, such as during the creation of open-cell
reticulated metal foam for gas turbine engine fan blades 60, for
example, is generally referred to by the reference number 88.
Generally speaking, such foam 88 may have a reticulated
three-dimensional structure comprising one or more ligaments 90
extending between two or more nodes 92. Being a three-dimensional
structure, a ligament 90 may extend between two or more nodes 92
out of the same plane.
[0047] Now turning specifically to FIG. 5, such foam 88 may
comprise a first layer 94 made of polymer foam having a void
fraction greater than or equal to ninety five (95) percent. While
other polymer foams are certainly possible, some polymer foams from
which the first layer 94 may be made includes polyurethane polymer
foam, polyvinyl chloride polymer foam, polystyrene polymer foam,
polyimide polymer foam, silicone polymer foam, polyethylene polymer
foam, polyester polymer foam, polypropylene foam and combinations
thereof. While such first layer 94 may have a void fraction of
ninety five (95) percent or greater, in another instance such layer
94 may have a void fraction greater than ninety six (96) percent.
In further instances, the first layer may have a void fraction
greater than ninety seven (97) percent, or even ninety eight (98)
percent.
[0048] As demonstrated in FIG. 5, such foam may further include a
second layer 96, and such second layer 96 may be adhered to the
first layer 94. Such second layer 96 may be an adhesive, such as an
adhesive polymer. Some adhesive polymers from which the second
layer may be made includes, but is certainly not limited to,
acrylic polymer, alkyd polymer, styrene acrylic polymer, styrene
butadiene polymer, vinyl acetate polymer, vinyl acetate homopolymer
polymer, vinyl acrylic polymer, vinyl maleate polymer, vinyl
versatate polymer, vinyl alcohol polymer, polyvinyl chloride
polymer, polyvinylpyrrolidone polymer, casein and combinations
thereof.
[0049] Such foam 88 may additionally include a third layer 98
adhered to the second layer 96 as depicted in FIGS. 6(a-b). While
specifically referring to FIG. 6a, it is seen that such third layer
98 may be comprised of a particulate material. Such particulate
material from which the third layer 98 may be made includes wax
powder, wood flour, polymer powder and combinations thereof. Some
wax powders from which the third layer 98 may be manufactured
includes, animal wax powder, vegetable wax powder, mineral wax
powder, petroleum wax powder and combinations thereof. Polymer
powders from which the third layer 98 may be made includes
polyurethane polymer powder, polyvinyl chloride polymer powder,
polystyrene polymer powder, polyimide polymer powder, polyethylene
polymer powder, polyester polymer powder, polypropylene polymer
powder and combinations thereof. Certainly, other polymer powders
may be utilized to manufacture the third layer 98 of the foam 88
for use in the creation of the open-celled metal foam for gas
turbine engine fan blades 60.
[0050] Such foam 88, comprising the first layer 94, second layer 96
adhered to the first layer 94 and third layer 98 adhered to the
second layer 94 may have void fraction less than or equal to ninety
five (95) percent. In another instance, such foam 88 may have void
fraction less than or equal to ninety four (94) percent. In a
further instance, such foam 88 may have void fraction less than or
equal to ninety three (93) percent. In further instances, such foam
88 comprising the first layer 94, second layer 96 adhered to the
first layer 94 and third layer 98 adhered to the second layer 94
may have void fraction less than or equal to ninety two (92)
percent, ninety one (91) percent or even ninety (90) percent.
[0051] Turning now to FIG. 6b, a modification of the foam 88
comprising the first layer 94, second layer 96 adhered to the first
layer 94 and third layer 98 adhered to the second layer 94, is
depicted. As seen there, the third layer 98 may be characterized as
being a substantially more continuous, non-particulate, shaped
coating. This third layer 98 may take on such continuous,
non-particulate, shaped characteristic upon the exposing the
particulate matter of the third layer 98 to heat energy that is at
or above the melting temperature of the particulate matter. That
is, the particulate matter melts, and subsequently upon cooling,
forms a substantially continuous coating of melted particulate
matter over the ligaments 90 and nodes 92 of the foam 88. Like the
foam 88 having a more particulate shaped third layer 98 depicted in
FIG. 6a, this foam 88 with a more continuous third layer 98 may
have a void fraction less than or equal to ninety five (95)
percent. In another instance, such foam 88 may have void fraction
less than or equal to ninety four (94) percent. In a further
instance, such foam 88 may have void fraction less than or equal to
ninety three (93) percent. In further instances, such foam 88
comprising the first layer 94, second layer 96 adhered to the first
layer 94 and third layer 98 adhered to the second layer 94 may have
void fraction less than or equal to two percent (92), ninety one
(91) percent or even ninety (90) percent.
[0052] While not depicted in FIGS. 5-6(a-b), such foam 88 may
additionally include a fourth layer comprising an adhesive adhered
to the third layer. Such adhesive may be an adhesive polymer and
may be selected from the list of adhesives described above in
paragraph [0047]. Alternatively, such adhesive may be a different
adhesive polymer altogether. Further, such foam 88 may additionally
comprise a fifth layer adhered to the fourth layer. Such fifth
layer may be a particulate material and the particulate material
may be a powder selected from such materials described in paragraph
[0048] of this application. Certainly other particulate materials
are possible. Additional adhesive and particulate material layers
may be added as needed so that the void fraction of the foam 88 for
use in a lost foam casting process is less than or equal to ninety
five (95) percent.
[0053] Turning now to FIG. 7, steps to a method of manufacturing
foam 88 for use in a lost-foam casting process, the foam 88 having
a void fraction less than or equal to ninety five (95) percent, are
illustrated. At a step 100, polymer foam having an open-cell
structure and a void fraction greater than ninety five (95) percent
may be provided. Such polymer foam may be selected, for example,
from the group consisting of polyurethane polymer foam, polyvinyl
chloride polymer foam, polystyrene polymer foam, polyimide polymer
foam, silicone polymer foam, polyethylene polymer foam, polyester
polymer foam, polypropylene foam and combinations thereof. At a
step 102, the polymer foam may be coated with an adhesive. Such
adhesive may be an adhesive polymer, for instance, and may be
selected from the group consisting of acrylic polymer, alkyd
polymer, styrene acrylic polymer, styrene butadiene polymer, vinyl
acetate polymer, vinyl acetate homopolymer polymer, vinyl acrylic
polymer, vinyl maleate polymer, vinyl versatate polymer, vinyl
alcohol polymer, polyvinyl chloride polymer, polyvinylpyrrolidone
polymer, casein and combinations thereof. Certainly, other adhesive
polymers are possible. At a step 104, a particulate material may be
applied to the adhesive, and the particulate material may be chosen
from the group consisting of wax powder, wood flour, polymer powder
and combinations thereof. Further, the wax powder may be selected
from the group consisting of animal wax powder, vegetable wax
powder, mineral wax powder, petroleum wax powder and combinations
thereof. If a polymer powder is chosen, it may be selected from the
group consisting of polyurethane polymer powder, polyvinyl chloride
polymer powder, polystyrene polymer powder, polyimide polymer
powder, polyethylene polymer powder, polyester polymer powder,
polypropylene polymer powder and combinations thereof.
Additionally, such particulate material may be applied by passing
the adhesive coated polymer foam through a fluidized bed of
particulate material.
[0054] When coating the polymer foam with an adhesive at step 102,
such step may comprise applying an emulsion to the polymer foam.
Such emulsion may comprise any of the foregoing described adhesive
polymers dispersed in a solvent. Further, such step may further
include removing the excess solvent from the polymer foam before
applying a particulate material to the adhesive.
[0055] In an addition to the process described above, the polymer
foam comprises ligaments positioned between nodes, and may further
comprise heating the foam to a temperature above the melting
temperature of the particulate material, followed by cooling the
foam to a temperature below the melting temperature of the
particulate material, to form a substantially continuous coating of
particulate material over the ligaments.
[0056] In an optional additional step, the third layer may be
coated with a fourth layer, the fourth layer comprising an
adhesive. Such adhesive may be an adhesive polymer selected from
the list described above in paragraph [0052], but other adhesive
polymers are certainly possible. Then, such fourth layer may be
coated with a fifth layer comprising particulate material. Such
particulate material may be a powder chosen from those described
above in paragraph [0052], although other materials are possible.
Additionally, such foam 88 may be coated with additional adhesive
and particulate material layers beyond the fourth and fifth layer
until the void fraction of the foam 88 for use in a lost-foam
casting process is less than or equal to ninety five (95)
percent.
[0057] Referring next to FIG. 8, steps to a method of manufacturing
a fan blade 60 for a gas turbine engine 20 are depicted. At a step
106, polymer foam having an open-cell structure and a void fraction
greater than ninety five (95) percent may be provided. At a step
108, the polymer foam may be coated with an adhesive to create
adhesive coated foam. At a step 110, particulate material may be
applied to the adhesive coated foam to make a modified foam having
a void fraction less than or equal to ninety five (95) percent. At
a step 112, the modified foam having a void fraction less than or
equal to ninety five (95) percent may covered with a refractory
material. At a step 114, the refractory material may be cured until
it hardens and forms an investment. At a step 116, the investment
may be heated to a temperature above the boiling point of the
modified foam having a void fraction less than or equal to ninety
five (95) percent to form a negative of the modified foam. At a
step 118, molten metal or metal alloy may be added adding to the
negative, followed by cooling the negative to a temperature below
the melting temperature of the metal or metal alloy to form a
positive of the modified foam. At a step 120, the refractory
material may be removed to form an open-cell metal foam having a
void fraction less than or equal to ninety five (95) percent. At a
step 122, the open-cells metal foam having a void fraction less
than or equal to ninety five (95) percent may be enveloped with an
outer shell of a first material, the out shell having the shape of
an airfoil, to form a fan blade for a gas turbine engine.
[0058] In one instance of the foregoing method, the polymer foam is
polyurethane polymer foam, the adhesive is vinyl acetate, the
particulate material is polyethylene polymer powder and the metal
or metal alloy is aluminum. Further, the outer shell of first
material may be made of a metal or metal alloy that is from the
group consisting of aluminum, titanium and nickel, aluminum alloys,
steel, nickel alloys and titanium alloys. Alternatively, the outer
shell of first material may be made of a composite material and
this composite material may comprise fiber embedded in resin.
INDUSTRIAL APPLICABILITY
[0059] In operation, foam for use in a lost-foam casting process
can find use in many industrial applications, such as in the
creation of open-cell reticulated metal foams for use in gas
turbine engine fan blades. More specifically, the foam may find use
as a positive in the lost-foam casting process for open-cell
reticulated metal foams. The void fraction of foam utilized in such
process is typically ninety seven (97) percent. While not
conclusive, data suggests that gas turbine engine fan blades
comprising open-cell reticulated metal foam manufactured from the
above-described foams lack the resilience necessary for use in such
fan blades.
[0060] Accordingly, the current application describes foam that can
be used in a lost-foam casting process to create open-cell
reticulated metal foam with a lesser void fraction. Such foam may
include a first layer comprising a polymer foam having a void
fraction greater than ninety five (95) percent, a second layer
comprising an adhesive adhered to the first layer and a third layer
of particulate material adhered to the third layer. Such foam,
having these three layers, has a void fraction that is less than or
equal to ninety five (95) percent and therefore may be used in a
lost-foam casting process to create an open-cell reticulated metal
foam having the necessary resilience to be used in gas turbine
engine fan blades. Additionally, methods are described to
manufacture such foam having three layers with the necessary void
fraction. Further, methods are described to create a fan blade for
a gas turbine engine utilizing the afore-described foam having
three layers with the necessary void fraction.
[0061] The above description is meant to be representative only,
and thus modifications may be made to the embodiments described
herein without departing from the scope of the disclosure. Thus,
these modifications fall within the scope of present disclosure and
are intended to fall within the appended claims.
* * * * *