U.S. patent application number 15/957759 was filed with the patent office on 2019-10-24 for integrated tooling for abrasive flow machining.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. The applicant listed for this patent is UNITED TECHNOLOGIES CORPORATION. Invention is credited to Henry H. Thayer, Wendell V. Twelves, Anthony Patrick Ventura.
Application Number | 20190321934 15/957759 |
Document ID | / |
Family ID | 66105053 |
Filed Date | 2019-10-24 |
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United States Patent
Application |
20190321934 |
Kind Code |
A1 |
Ventura; Anthony Patrick ;
et al. |
October 24, 2019 |
INTEGRATED TOOLING FOR ABRASIVE FLOW MACHINING
Abstract
A cluster-tool assembly for abrasive flow machining a plurality
of airfoils is disclosed. The cluster-tool assembly comprises an
airfoil cluster, the airfoil cluster including a supporting rail
and the plurality of airfoils spaced about the supporting rail, and
a sacrificial tool unitarily formed with the airfoil cluster, the
sacrificial tool including a body and a plurality of prongs
extending from the body.
Inventors: |
Ventura; Anthony Patrick;
(South Glastonbury, CT) ; Twelves; Wendell V.;
(Glastonbury, CT) ; Thayer; Henry H.;
(Wethersfield, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UNITED TECHNOLOGIES CORPORATION |
Farmington |
CT |
US |
|
|
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Farmington
CT
|
Family ID: |
66105053 |
Appl. No.: |
15/957759 |
Filed: |
April 19, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24C 5/00 20130101; B33Y
80/00 20141201; B24B 31/116 20130101; B24C 7/0092 20130101; B24C
3/327 20130101; F05D 2230/14 20130101; F05D 2240/12 20130101; B24B
19/14 20130101; B33Y 40/00 20141201; B24C 1/08 20130101 |
International
Class: |
B24B 31/116 20060101
B24B031/116; B24B 19/14 20060101 B24B019/14 |
Claims
1. A cluster-tool assembly for abrasive flow machining of a
plurality of airfoils, comprising: an airfoil cluster, the airfoil
cluster including a supporting rail and the plurality of airfoils
spaced about the supporting rail; and a sacrificial tool unitarily
formed with the airfoil cluster, the sacrificial tool including a
body and a plurality of prongs extending from the body.
2. The cluster-tool assembly of claim 1, wherein a first airfoil of
the plurality of airfoils is positioned between a first prong and a
second prong of the plurality of prongs.
3. The cluster-tool assembly of claim 2, wherein the first airfoil
includes a foil tip portion unitarily connected to the body of the
sacrificial tool.
4. The cluster-tool assembly of claim 3, wherein the first airfoil
defines a length from a leading edge to a trailing edge and wherein
a first side channel extends along the length between a convex foil
surface of the first airfoil and a concave prong surface of the
first prong.
5. The cluster-tool assembly of claim 4, wherein a second side
channel extends along the length between a concave foil surface of
the first airfoil and a convex prong surface of the second
prong.
6. The cluster-tool assembly of claim 5, wherein the first prong
includes a first prong tip portion positioned adjacent a first
platform portion of the supporting rail, defining a first platform
channel that extends along the length proximate a first base
portion of the convex foil surface of the first airfoil.
7. The cluster-tool assembly of claim 6, wherein the second prong
includes a second prong tip portion positioned adjacent a second
platform portion of the supporting rail, defining a second platform
channel that extends along the length proximate a second base
portion of the concave foil surface of the first airfoil.
8. The cluster-tool assembly of claim 6, wherein the first side
channel defines a channel width along the length, wherein the first
platform channel defines a channel height along the length and
wherein the channel height is greater than the channel width.
9. The cluster-tool assembly of claim 1, wherein each one of the
plurality of airfoils includes a foil tip portion unitarily
connected to the body of the sacrificial tool and wherein each one
of the plurality of airfoils is positioned between a first prong
and a second prong.
10. The cluster-tool assembly of claim 9, wherein each one of the
plurality of airfoils includes a convex foil surface positioned
adjacent a concave prong surface of the first prong and a concave
foil surface positioned adjacent a convex prong surface of the
second prong.
11. The cluster-tool assembly of claim 10, wherein each one of the
plurality of airfoils defines a length from a leading edge to a
trailing edge and wherein a first side channel extends along the
length between a first foil surface of each one of the plurality of
airfoils and a first prong surface of an adjacent prong of the
plurality of prongs.
12. The cluster-tool assembly of claim 9, wherein each one of the
plurality of airfoils defines a length from a leading edge to a
trailing edge and wherein a first side channel extends along the
length between a convex foil surface of each one of the plurality
of airfoils and a concave prong surface of a first adjacent one of
the plurality of prongs and wherein a second side channel extends
along the length between a concave foil surface of each one of the
plurality of airfoils and a convex prong surface of a second
adjacent one of the plurality of prongs.
13. An abrasive flow machine for polishing surfaces of a plurality
of airfoils, comprising: a housing; an abrasive media contained
within the housing; a driver operatively associated with the
abrasive media to cause the abrasive media to flow over the
surfaces of the plurality of airfoils; and a fixture configured to
retain a cluster-tool assembly within the flow of the abrasive
media, the cluster-tool assembly comprising an airfoil cluster and
a sacrificial tool unitarily formed with the airfoil cluster.
14. The abrasive flow machine of claim 13, wherein the airfoil
cluster comprises a supporting rail, wherein the plurality of
airfoils is equally spaced about the supporting rail, and wherein
the sacrificial tool comprises a body and a plurality of prongs
extending from the body.
15. The abrasive flow machine of claim 14, wherein each one of the
plurality of airfoils includes a foil tip portion unitarily
connected to the body of the sacrificial tool and wherein each one
of the plurality of airfoils is positioned between a first prong
and a second prong.
16. The abrasive flow machine of claim 15, wherein each one of the
plurality of airfoils includes a convex foil surface positioned
adjacent a concave prong surface of the first prong and a concave
foil surface positioned adjacent a convex prong surface of the
second prong.
17. A method for polishing surfaces of a plurality of airfoils,
comprising: fabricating a cluster-tool assembly, the cluster-tool
assembly including an airfoil cluster and a sacrificial tool
unitarily formed with the airfoil cluster, wherein the airfoil
cluster includes a supporting rail and the plurality of airfoils
spaced about the supporting rail, wherein the sacrificial tool
comprises a body and a plurality of prongs extending from the body,
wherein a first airfoil of the plurality of airfoils is positioned
between a first prong and a second prong of the plurality of prongs
and wherein the first airfoil includes a foil tip portion unitarily
connected to the body of the sacrificial tool; positioning the
cluster-tool assembly within an abrasive flow machine; and flowing
an abrasive media through a first side channel extending between a
convex foil surface of the first airfoil and a concave prong
surface of the first prong and a second side channel extending
between a concave foil surface of the first airfoil and a convex
prong surface of the second prong.
18. The method of claim 17, wherein the first prong includes a
first prong tip portion positioned adjacent a first platform
portion of the supporting rail, defining a first platform channel
that extends proximate a first base portion of the convex foil
surface of the first airfoil and wherein the abrasive media is
urged through the first platform channel.
19. The method of claim 18, wherein the second prong includes a
second prong tip portion positioned adjacent a second platform
portion of the supporting rail, defining a second platform channel
that extends proximate a second base portion of the concave foil
surface of the first airfoil and wherein the abrasive media is
urged through the second platform channel.
20. The method of claim 17, further comprising terminating the flow
of abrasive media and removing any portion of the sacrificial tool
that remains connected to the airfoil cluster.
Description
FIELD
[0001] The present disclosure relates generally to apparatus and
methods for abrasive flow machining and, more particularly, to
apparatus and methods for abrasive flow machining used to polish or
finish surfaces of airfoil clusters for gas turbine engines.
BACKGROUND
[0002] Abrasive flow machining is a process with application to
polishing or finishing surfaces of metal parts following initial
fabrication through, for example, casting or additive
manufacturing. The process has been found to be advantageous for
polishing or finishing of manufactured parts having complex
structural features such as, for example, internal passages or
buried cavities that include surfaces that are difficult to access
by other surface finishing techniques.
[0003] Abrasive flow machining has been employed as a manufacturing
step in the production of surface finished airfoil clusters for gas
turbine engines. The airfoil clusters may consist of a plurality of
airfoils attached to a supporting rail to form a unitary structure.
Due to the complex structural features of the airfoil clusters,
surface polishing by abrasive flow machining may prove more
effective than other polishing methods that exhibit difficulties in
finishing or polishing various regions of the airfoil cluster to a
desired degree.
[0004] While abrasive flow machining may provide an effective
method for surface polishing of airfoil clusters, differential
finishing (or uneven surface polishing) of various regions of the
airfoil clusters may occur in certain cases. As a result, various
surfaces of the airfoil cluster may receive more surface polishing
and more difficult to reach surfaces may be left with undesirable
surface roughness. Difficult to reach surface areas may include,
for example, the concave surfaces and the root radii of the
airfoils and the platforms located on the support rail between each
adjacent pair of airfoils.
SUMMARY
[0005] A cluster-tool assembly for abrasive flow machining of a
plurality of airfoils is disclosed. In various embodiments, the
cluster-tool assembly includes an airfoil cluster, the airfoil
cluster including a supporting rail and the plurality of airfoils
spaced about the supporting rail, and a sacrificial tool unitarily
formed with the airfoil cluster, the sacrificial tool including a
body and a plurality of prongs extending from the body.
[0006] In various embodiments, a first airfoil of the plurality of
airfoils is positioned between a first prong and a second prong of
the plurality of prongs. In various embodiments, the first airfoil
includes a foil tip portion unitarily connected to the body of the
sacrificial tool. In various embodiments, the first airfoil defines
a length from a leading edge to a trailing edge and a first side
channel extends along the length between a convex foil surface of
the first airfoil and a concave prong surface of the first prong.
In various embodiments, a second side channel extends along the
length between a concave foil surface of the first airfoil and a
convex prong surface of the second prong.
[0007] In various embodiments, the first prong includes a first
prong tip portion positioned adjacent a first platform portion of
the supporting rail, defining a first platform channel that extends
along the length proximate a first base portion of the convex foil
surface of the first airfoil. In various embodiments, the second
prong includes a second prong tip portion positioned adjacent a
second platform portion of the supporting rail, defining a second
platform channel that extends along the length proximate a second
base portion of the concave foil surface of the first airfoil. In
various embodiments, the first side channel defines a channel width
along the length, the first platform channel defines a height along
the length and the height is greater than the width.
[0008] In various embodiments, each one of the plurality of
airfoils includes a foil tip portion unitarily connected to the
body of the sacrificial tool and each one of the plurality of
airfoils is positioned between a first prong and a second prong. In
various embodiments, each one of the plurality of airfoils includes
a convex foil surface positioned adjacent a concave prong surface
of the first prong and a concave foil surface positioned adjacent a
convex prong surface of the second prong. In various embodiments,
each one of the plurality of airfoils defines a length from a
leading edge to a trailing edge and a first side channel extends
along the length between a first foil surface of each one of the
plurality of airfoils and a first prong surface of an adjacent
prong of the plurality of prongs.
[0009] In various embodiments, each one of the plurality of
airfoils defines a length from a leading edge to a trailing edge, a
first side channel extends along the length between a convex foil
surface of each one of the plurality of airfoils and a concave
prong surface of a first adjacent one of the plurality of prongs
and a second side channel extends along the length between a
concave foil surface of each one of the plurality of airfoils and a
convex prong surface of a second adjacent one of the plurality of
prongs.
[0010] An abrasive flow machine for polishing surfaces of a
plurality of airfoils is disclosed. In various embodiments, the
machine comprises a housing; an abrasive media contained within the
housing; a driver operatively associated with the abrasive media to
cause the abrasive media to flow over the surfaces of the plurality
of airfoils; and a fixture configured to retain a cluster-tool
assembly within the flow of the abrasive media, the cluster-tool
assembly comprising an airfoil cluster and a sacrificial tool
unitarily formed with the airfoil cluster.
[0011] In various embodiments, the airfoil cluster comprises a
supporting rail, the plurality of airfoils being equally spaced
about the supporting rail, and the sacrificial tool comprises a
body and a plurality of prongs extending from the body. In various
embodiments, each one of the plurality of airfoils includes a foil
tip portion unitarily connected to the body of the sacrificial tool
and each one of the plurality of airfoils is positioned between a
first prong and a second prong. In various embodiments, each one of
the plurality of airfoils includes a convex foil surface positioned
adjacent a concave prong surface of the first prong and a concave
foil surface positioned adjacent a convex prong surface of the
second prong.
[0012] A method for polishing surfaces of a plurality of airfoils
is disclosed. In various embodiments, the method comprises
fabricating a cluster-tool assembly, the cluster-tool assembly
including an airfoil cluster and a sacrificial tool unitarily
formed with the airfoil cluster, where the airfoil cluster includes
a supporting rail and the plurality of airfoils is spaced about the
supporting rail, where the sacrificial tool comprises a body and a
plurality of prongs extending from the body, where a first airfoil
of the plurality of airfoils is positioned between a first prong
and a second prong of the plurality of prongs and where the first
airfoil includes a foil tip portion unitarily connected to the body
of the sacrificial tool. In various embodiments, the method further
comprises positioning the cluster-tool assembly within an abrasive
flow machine and flowing an abrasive media through a first side
channel extending between a convex foil surface of the first
airfoil and a concave prong surface of the first prong and a second
side channel extending between a concave foil surface of the first
airfoil and a convex prong surface of the second prong.
[0013] In various embodiments, the first prong includes a first
prong tip portion positioned adjacent a first platform portion of
the supporting rail, defining a first platform channel that extends
proximate a first base portion of the convex foil surface of the
first airfoil, and the abrasive media is urged through the first
platform channel. In various embodiments, the second prong includes
a second prong tip portion positioned adjacent a second platform
portion of the supporting rail, defining a second platform channel
that extends proximate a second base portion of the concave foil
surface of the first airfoil, and the abrasive media is urged
through the second platform channel. In various embodiments, the
method further comprises terminating the flow of abrasive media and
removing any portion of the sacrificial tool that remains connected
to the airfoil cluster.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The subject matter of the present disclosure is particularly
pointed out and distinctly claimed in the concluding portion of the
specification. A more complete understanding of the present
disclosure, however, may best be obtained by referring to the
following detailed description and claims in connection with the
following drawings. While the drawings illustrate various
embodiments employing the principles described herein, the drawings
do not limit the scope of the claims.
[0015] FIG. 1 is a cross sectional schematic view of a gas turbine
engine, in accordance with various embodiments;
[0016] FIG. 2A is a perspective schematic view of an airfoil
cluster, in accordance with various embodiments;
[0017] FIG. 2B is an axial schematic view of an airfoil assembly
formed using several of the airfoil clusters illustrated in FIG.
2A, in accordance with various embodiments;
[0018] FIG. 3A is a perspective schematic view of a cluster-tool
assembly, comprising a sacrificial tool and an airfoil cluster, in
accordance with various embodiments;
[0019] FIG. 3B is a perspective schematic view of the indicated
portion of the cluster-tool assembly illustrated in FIG. 3A, in
accordance with various embodiments;
[0020] FIG. 4A is a cross-sectional schematic view of an abrasive
flow machine configured to finish several assemblies of sacrificial
tools and airfoil clusters retained by a fixture, in accordance
with various embodiments;
[0021] FIG. 4B is an axial schematic view of several assemblies of
sacrificial tools and airfoil clusters retained by a fixture in an
abrasive flow machine, in accordance with various embodiments;
[0022] FIG. 5 is a cross-sectional schematic view through the
section 5-5 of FIG. 3A, illustrating the flow of abrasive media
through side channels of the cluster-tool assembly, in accordance
with various embodiments; and
[0023] FIG. 6 is a flow chart diagram, illustrating steps involved
in finishing several assemblies of sacrificial tools and airfoil
clusters retained by a fixture, in accordance with various
embodiments.
DETAILED DESCRIPTION
[0024] The following detailed description of various embodiments
herein makes reference to the accompanying drawings, which show
various embodiments by way of illustration. While these various
embodiments are described in sufficient detail to enable those
skilled in the art to practice the disclosure, it should be
understood that other embodiments may be realized and that changes
may be made without departing from the scope of the disclosure.
Thus, the detailed description herein is presented for purposes of
illustration only and not of limitation. Furthermore, any reference
to singular includes plural embodiments, and any reference to more
than one component or step may include a singular embodiment or
step. Also, any reference to attached, fixed, connected, or the
like may include permanent, removable, temporary, partial, full or
any other possible attachment option. Additionally, any reference
to without contact (or similar phrases) may also include reduced
contact or minimal contact. It should also be understood that
unless specifically stated otherwise, references to "a," "an" or
"the" may include one or more than one and that reference to an
item in the singular may also include the item in the plural.
Further, all ranges may include upper and lower values and all
ranges and ratio limits disclosed herein may be combined.
[0025] Referring now to the drawings, FIG. 1 schematically
illustrates a gas turbine engine 20. The gas turbine engine 20 is
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 augmenter section (not shown) among other systems or
features. The fan section 22 drives air along a bypass flow path B
in a bypass duct defined within a nacelle 15, while the compressor
section 24 drives air along a primary or core flow path C for
compression and communication into the combustor section 26 and
then expansion through the turbine section 28. Although depicted as
a two-spool turbofan gas turbine engine in the disclosed
non-limiting embodiment, it will be understood that the concepts
described herein are not limited to use with two-spool turbofans as
the teachings may be applied to other types of turbine engines,
including three-spool architectures.
[0026] The gas turbine 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 at various locations may
alternatively or additionally be provided and the location of the
several bearing systems 38 may be varied as appropriate to the
application. The low speed spool 30 generally includes an inner
shaft 40 that interconnects a fan 42, a low pressure compressor 44
and a low pressure turbine 46. The inner shaft 40 is connected to
the fan 42 through a speed change mechanism, which in this gas
turbine engine 20 is illustrated as a fan drive gear system 48
configured to drive the fan 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 compressor 52 and a high pressure
turbine 54. A combustor 56 is arranged in the gas turbine engine 20
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 and may include airfoils 59 in the core
flow path C for guiding the flow into the low pressure turbine 46.
The mid-turbine frame 57 further supports the several bearing
systems 38 in the turbine section 28. The inner shaft 40 and the
outer shaft 50 are concentric and rotate via the several bearing
systems 38 about the engine central longitudinal axis A, which is
collinear with their longitudinal axes.
[0027] The air in the core flow path is compressed by the low
pressure compressor 44 and then the high pressure compressor 52,
mixed and burned with fuel in the combustor 56, and then expanded
over the high pressure turbine 54 and low pressure turbine 46. The
low pressure turbine 46 and the high pressure turbine 54
rotationally drive the respective low speed spool 30 and the high
speed spool 32 in response to the expansion. It will be appreciated
that each of the positions of the fan section 22, the compressor
section 24, the combustor section 26, the turbine section 28, and
the fan drive gear system 48 may be varied. For example, the fan
drive gear system 48 may be located aft of the combustor section 26
or even aft of the turbine section 28, and the fan section 22 may
be positioned forward or aft of the location of the fan drive gear
system 48.
[0028] Referring now to FIG. 2A, an airfoil cluster 200 is shown.
The airfoil cluster 200 may, for example, be a cluster of vanes in
a stator section of one or more of the turbine sections and the
compressor sections referred to above with reference to FIG. 1. In
various embodiments, the airfoil cluster 200 includes a plurality
of airfoils 202 attached to a supporting rail 204. In various
embodiments, the airfoils 202 and the supporting rail 204 may be
formed separately and then assembled to form the airfoil cluster
200. In various embodiments, each of the airfoils 202 may have a
leading edge 206, a trailing edge 208 and a root radii 210 near the
base of the airfoils 202, as illustrated. In addition, each of the
airfoils 202 may have a concave surface 212 (pressure side of
airfoil) and a convex surface 214 (suction side of airfoil).
Between each adjacent pair of the plurality of airfoils 202 may be
a platform 216 along a radially inward surface of the supporting
rail 204, as illustrated. Throughout the disclosure, the convex and
concave surfaces of the airfoils may sometimes be referred to as
convex and concave foil surfaces.
[0029] Referring now to FIG. 2B, in various embodiments, an airfoil
assembly 250 includes a plurality of airfoil clusters 252, each
cluster comprising, for example, the components of the airfoil
cluster 200 described above with reference to FIG. 2A. The
plurality of airfoil clusters 252 may be interconnected at
connection points 254 to form the airfoil assembly 250, which may
have an annular structure, as illustrated in FIG. 2B. In various
embodiments, the plurality of airfoil clusters 252 includes nine
individual airfoil clusters assembled to form the airfoil assembly
250. Alternatively, the airfoil assembly 250 may comprise other
numbers of airfoil clusters or, in various embodiments, a single
ring-like airfoil cluster. In various embodiments, the airfoil
assembly 250 may form a stage of a high pressure compressor of a
gas turbine engine, such as, for example, the high pressure
compressor 52 described above with reference to FIG. 1. For
example, the airfoil assembly 250 may be a stator vane assembly
forming one stage of a high pressure compressor. In various
embodiments, the airfoil assembly 250 may be a component of another
region of a gas turbine engine, such as, for example, the rotor
blades or stator vanes of the low pressure compressor or the high
or low pressure turbine sections described above with reference to
FIG. 1.
[0030] In various embodiments, the airfoil cluster 200 may be
formed from metal and be manufactured by a 3D-printing or additive
manufacturing technique, such as, for example, direct metal laser
sintering (DMLS). Following manufacture, in some circumstances,
certain regions of the airfoil cluster 200 such as, for example,
the concave surface 212, the convex surface 214, the platform 216
and the root radii 210 of each of the plurality of airfoils 202 may
have rough surfaces. In order to bring the surface roughness of the
various regions of the airfoil cluster 200 to a desired smoothness
or to remove excess material to meet part specifications and
quality regulations, the airfoil cluster 200 may require surface
polishing prior to distribution and incorporation into the airfoil
assembly 250 and the gas turbine engine. Typically, such surface
polishing will target areas of the airfoil cluster 200 that may be
characterized by high surface roughness following manufacture
(e.g., the concave surface 212, the convex surface 214, the
platform 216 and the root radii 210 of each of the plurality of
airfoils 202). The below disclosure provides apparatus and methods
that may be employed to finish or polish the regions of high
surface roughness to desirable levels, in accordance with various
embodiments.
[0031] Referring now to FIGS. 3A and 3B, an airfoil cluster 300
having a plurality of airfoils 302 is illustrated in combination
with a sacrificial tool 320 to form a cluster-tool assembly 330. In
various embodiments, the cluster-tool assembly 330 is manufactured
as a unitary component, using a 3D-printing or additive
manufacturing technique, such as, for example, DMLS. In the
discussion that follows, while the cluster-tool assembly 330 is a
unitary component, comprising the airfoil cluster 300 and the
sacrificial tool 320, it is sometimes helpful to describe the
cluster-tool assembly 330 with respect to its individual
components. For example, in various embodiments, the sacrificial
tool 320 may be described as including a comb-like structure
comprising a body 364 from which a plurality of prongs 366 may
extend. Each one of the plurality of prongs 366 is dimensioned to
extend between adjacent pairs of the plurality of airfoils 302 of
the airfoil cluster 300 leaving spaces there between. When the
cluster-tool assembly 330 is viewed as a unitary structure, the
body 364 is connected between adjacent pairs of the plurality of
prongs 366 to tip portions 317 corresponding to each airfoil of the
plurality of airfoils 302, which results from the additive process
used to fabricate the cluster-tool assembly 330 as a unitary,
single-piece unit.
[0032] More specifically, each of the plurality of prongs 366 may
be configured to reside between a convex surface 314 of an airfoil
from the plurality of airfoils 302 and a concave surface 312 of an
immediately adjacent airfoil from the plurality of airfoils 302
without coming into physical contact with the concave and convex
surfaces of the airfoils. Each of the plurality of prongs 366 may
have a length 340 in an axial direction that equals or exceeds a
length of each of the plurality of airfoils 302, as measured from a
leading edge to a trailing edge, such as the leading edge 206 and
the trailing edge 208 described above with reference to FIG. 2A. In
addition, each of the plurality of prongs 366 may have a concave
surface 368 and a convex surface 370, each having a shape and
curvature identical to, or at least substantially identical to, the
concave surface 312 and the convex surface 314 of each one of the
plurality of airfoils 302, respectively. In this regard, the
sacrificial tool 320 may be custom designed according to the
geometry of each of the plurality of airfoils 302 of the airfoil
cluster 300.
[0033] Still referring to FIGS. 3A and 3B, each of the plurality of
prongs 366 of the sacrificial tool 320 may define side channels 375
between each of the plurality of prongs 366 and the concave and
convex surfaces of adjacent pair of airfoils. The side channels 375
may, for example, include a first side channel 376 formed between a
concave surface 342 of a first prong 343 and a convex surface 344
of a first airfoil 378, and a second side channel 377 formed
between a convex surface 345 of the first prong 343 and a concave
surface 346 of a second airfoil 379, wherein the first airfoil 378
and the second airfoil 379 are immediately adjacent airfoils in the
airfoil cluster 300. In various embodiments, each of the side
channels 375 in the cluster-tool assembly 330 has a channel width,
W, which may be constant or vary along the length 340 of the side
channel. Further, each of the side channels 375 in the cluster-tool
assembly 330 may define a flow path providing for flow of abrasive
media there through during an abrasive flow polishing process and
control of the velocity of the abrasive media over the concave
surface 312, the convex surface 314, the leading edge, and the
trailing edge of each of the plurality of airfoils 302. In
addition, the channel width, W, of the side channels 375 may be
fixed along the length 340 (from forward to aft) of the side
channels 375. This arrangement may assist in providing a uniform
flow velocity of the abrasive media across the surfaces of each of
the plurality of airfoils 302, including the concave and convex
surfaces of each of the airfoils. The channel width, W, of the side
channels 375 may also vary depending on the polishing
specifications of the airfoil cluster 300 as well as on the
consistency of the abrasive media. As a non-limiting possibility,
the channel width, W, of the side channels 375 may be about 0.07
inches (about 1.8 mm), but may be greater for more viscous abrasive
media or lesser for less viscous abrasive media. Throughout the
disclosure, the convex and concave surfaces of the airfoils may
sometimes be referred to as convex and concave foil surfaces.
Similarly, the convex and concave surfaces of the prongs may
sometimes be referred to as convex and concave prong surfaces.
[0034] With continued reference to FIGS. 3A and 3B, each of the
plurality of prongs 366 of the sacrificial tool 320 may have a tip
portion 380 that, when manufactured unitarily with the airfoil
cluster 300, may be positioned adjacent a platform 316, which
defines a platform channel 382 there between. The abrasive media
may flow through the platform channel 382 during the abrasive flow
polishing process and the platform channel 382 may assist in
controlling the velocity of the flow of the abrasive media over the
surfaces of both the platform 322 and a corresponding pair of root
radii 310. Each platform channel 382 may have a channel height, H,
as measured by the distance from the tip portion 380 of each of the
plurality of prongs 366 to the platform 322 corresponding thereto.
In one possible arrangement, each channel height, H, may be greater
than the channel width, W, of the side channels 375. As a
non-limiting possibility, the channel height, H, of the platform
channel 382 may be up to about two times greater than the channel
width, W, of the side channels 375. For example, the channel
height, H, of each platform channel 382 may be about 0.14 inches
(about 3.6 mm) wide, but other channel heights are certainly
possible depending on the airfoil cluster geometry or the viscosity
of the abrasive media. In addition, in various embodiments, the
channel height, H, of the platform channel 382 may be equal to or
less than the channel width, W, of the side channels 375.
[0035] When manufactured as a unitary component, the cluster-tool
assembly 330, comprising the airfoil cluster 300 and the
sacrificial tool 320, may assist in targeting certain surfaces of
the airfoil cluster 300 for enhanced polishing. More specifically,
given that the velocity of the flow of the abrasive media through
the side channels 375 and each platform channel 382 may be directly
correlated with the channel width, W, and the channel height, H,
and that each platform channel 382 may be wider than the side
channels 375, the abrasive media may flow with higher velocities in
the platform channel 382 than in the side channels 375 during the
abrasive flow polishing process. Consequently, the surfaces of the
airfoil cluster 300 that are located in each platform channel 382
may experience greater abrasive wear and enhanced polishing as
compared to the surfaces located in the side channels 375. In
similar fashion, the channel width, W, and the channel height, H,
may be adjusted relative to one another to enhance the polishing of
the concave and convex surfaces of each airfoil relative to the
platform and root radii surfaces. In various embodiments, the
channel width, W, may vary along the span or length of each
airfoil, from root to tip, to enhance polishing at, for example,
the tip of the airfoil relative to the root of the airfoil. As can
be appreciated, the sacrificial tool 320 may have alternative
configurations creating different flow channel geometries to direct
enhanced abrasive activity to other selected regions of the airfoil
cluster 300.
[0036] Referring now to FIGS. 4A and 4B, an abrasive flow machine
400 configured for abrasive flow polishing of one or more
cluster-tool assemblies 430, such as the cluster-tool assembly 330,
comprising the airfoil cluster 300 and the sacrificial tool 320,
described above with reference to FIGS. 3A and 3B is illustrated.
In various embodiments, the abrasive flow machine 400 comprises a
housing 402 for containing an abrasive media 404. The abrasive
media 404 may have a viscous, gel-like or putty-like consistency
and it may be permeated with an abrasive material that may act to
abrade and polish surfaces of one or more airfoil clusters 406 and
wear away the material comprising one or more sacrificial tools 408
corresponding to the airfoil clusters 406. The abrasive flow
machine 400 may include a fixture 410 configured to retain each of
the duster-tool assemblies 430, which comprise the airfoil dusters
406 and sacrificial tools 408 in a static position during the
abrasive flow polishing process. The abrasive flow machine 400 may
include a driver 412 to cause the abrasive media 404 to flow over
the surfaces of the cluster-tool assemblies 430. The driver 412 may
drive a pair of opposing pistons 422 to direct the abrasive media
404 back and forth in a reciprocating motion between an upper
chamber 414 and a lower chamber 416 of the housing 402. In
operation, the pair of opposing pistons 422 direct the abrasive
media 404 in a forward direction 418, causing the abrasive media
404 to flow from the upper chamber 414 to the lower chamber 416,
and in a reverse direction 420, causing the abrasive media 404 to
flow from the lower chamber 416 to the upper chamber 414. During
this process, the abrasive media 404 flows back and forth over the
surfaces of the duster-tool assemblies 430, including the airfoil
dusters 406 and the sacrificial tools 408. As illustrated, the
fixture 410 may retain a plurality of the cluster-tool assemblies
430 during abrasive flow polishing.
[0037] Referring now to FIG. 5, a schematic depiction of the flow
of abrasive media 504 through a cross section of a cluster-tool
assembly 530, such as the cluster-tool assembly 330 described above
with reference to FIGS. 3A and 3B is illustrated. As illustrated,
the cluster-tool assembly comprises a plurality of airfoils 502
positioned between a plurality of prongs 566. A plurality of side
channels 575, such as the side channels 375 described above with
reference to FIGS. 3A and 3B, extend along a length of each of the
plurality of airfoils 502. Each of the side channels 575 may have a
curvature that matches, or at least substantially matches, the
curvature of the concave and convex surfaces of the plurality of
airfoils 502. Accordingly, the flow of the abrasive media 504 in
both a forward direction 518 and the reverse direction 520 may
follow a curved pathway 585 having a curvature that matches, or at
least substantially matches, the curvature of each of the plurality
of airfoils 502.
[0038] Referring now to FIG. 6, a method 600 for finishing or
polishing a plurality of airfoils within a cluster-tool assembly,
comprising an airfoil cluster and a sacrificial tool, is provided.
Beginning with the first block 602, one or more cluster-tool
assemblies, each including an airfoil cluster and a sacrificial
tool, is fabricated. The cluster-tool assemblies may be fabricated
using an additive process. In various embodiments, the material
used to fabricate the sacrificial portion of the cluster-tool
assembly is made of a softer material than the material used to
fabricate the airfoil cluster. In a second step 604, the
cluster-tool assemblies are positioned within and secured to a
fixture and the fixture is placed within an abrasive flow machine.
In a third step 606, abrasive flow machining is performed. In
various embodiments, the abrasive flow machining, such as that
described above with reference to FIGS. 4A and 4B, contemplates
reciprocating motion of an abrasive material through side channels
and platform channels within the cluster-tool assemblies, such that
the airfoils are polished while the sacrificial tool is abraded
away. Once the flow of the abrasive media is initiated, the
curvature and geometries of the side channels and the platform
channels (which may vary depending on the design of the airfoil
clusters and sacrificial tool components of the cluster-tool
assemblies) may assist in controlling the direction and velocity of
the flow of the abrasive media over the surfaces of the airfoil
cluster in order to target specific regions (e.g., the concave and
convex airfoil surfaces, the platforms and the root radii) of the
airfoil clusters for enhanced abrasion and polishing or to assist
preventing abrasive wear on selected regions of the airfoil. In a
fourth step 608, any residual material from the sacrificial tools
is removed from the airfoil clusters.
[0039] The foregoing provides an apparatus and method that may be
used to enhance post-processing (e.g., finishing or polishing) of
components by abrasive flow machining. In various embodiments, this
is accomplished by fabricating a sacrificial tool into the
component (e.g., an airfoil cluster) and exposing the combination
to abrasive flow media. The sacrificial component is configured to
beneficially guide the abrasive flow media toward regions of the
component that are either difficult to reach or require focused
smoothing or polishing of undesired roughness. Although this
approach is particularly amenable to components made through
additive manufacturing, the same principles according to the
disclosure may be applied to other methods of manufacture, such as
casting, used to create the combination of a desired component and
sacrificial tool having a geometry configured to tailor the flow of
abrasive material about various surfaces of the component.
[0040] Finally, it should be understood that any of the above
described concepts can be used alone or in combination with any or
all of the other above described concepts. Although various
embodiments have been disclosed and described, one of ordinary
skill in this art would recognize that certain modifications would
come within the scope of this disclosure. Accordingly, the
description is not intended to be exhaustive or to limit the
principles described or illustrated herein to any precise form.
Many modifications and variations are possible in light of the
above teaching.
[0041] Benefits, other advantages, and solutions to problems have
been described herein with regard to specific embodiments.
Furthermore, the connecting lines shown in the various figures
contained herein are intended to represent exemplary functional
relationships and/or physical couplings between the various
elements. It should be noted that many alternative or additional
functional relationships or physical connections may be present in
a practical system. However, the benefits, advantages, solutions to
problems, and any elements that may cause any benefit, advantage,
or solution to occur or become more pronounced are not to be
construed as critical, required, or essential features or elements
of the disclosure. The scope of the disclosure is accordingly to be
limited by nothing other than the appended claims, in which
reference to an element in the singular is not intended to mean
"one and only one" unless explicitly so stated, but rather "one or
more." Moreover, where a phrase similar to "at least one of A, B,
or C" is used in the claims, it is intended that the phrase be
interpreted to mean that A alone may be present in an embodiment, B
alone may be present in an embodiment, C alone may be present in an
embodiment, or that any combination of the elements A, B and C may
be present in a single embodiment; for example, A and B, A and C, B
and C, or A and B and C. Different cross-hatching is used
throughout the figures to denote different parts but not
necessarily to denote the same or different materials.
[0042] Systems, methods and apparatus are provided herein. In the
detailed description herein, references to "one embodiment", "an
embodiment", "various embodiments", etc., indicate that the
embodiment described may include a particular feature, structure,
or characteristic, but every embodiment may not necessarily include
the particular feature, structure, or characteristic. Moreover,
such phrases are not necessarily referring to the same embodiment.
Further, when a particular feature, structure, or characteristic is
described in connection with an embodiment, it is submitted that it
is within the knowledge of one skilled in the art to affect such
feature, structure, or characteristic in connection with other
embodiments whether or not explicitly described. After reading the
description, it will be apparent to one skilled in the relevant
art(s) how to implement the disclosure in alternative
embodiments.
[0043] Furthermore, no element, component, or method step in the
present disclosure is intended to be dedicated to the public
regardless of whether the element, component, or method step is
explicitly recited in the claims. No claim element herein is to be
construed under the provisions of 35 U.S.C. 112(f) unless the
element is expressly recited using the phrase "means for." As used
herein, the terms "comprises", "comprising", or any other variation
thereof, are intended to cover a non-exclusive inclusion, such that
a process, method, article, or apparatus that comprises a list of
elements does not include only those elements but may include other
elements not expressly listed or inherent to such process, method,
article, or apparatus.
* * * * *