U.S. patent application number 14/716402 was filed with the patent office on 2015-09-24 for system and method for forming elongated perforations in an inner barrel section of an engine.
This patent application is currently assigned to THE BOEING COMPANY. The applicant listed for this patent is THE BOEING COMPANY. Invention is credited to Mark F. Gabriel, Arnold J. Lauder.
Application Number | 20150267593 14/716402 |
Document ID | / |
Family ID | 54141642 |
Filed Date | 2015-09-24 |
United States Patent
Application |
20150267593 |
Kind Code |
A1 |
Lauder; Arnold J. ; et
al. |
September 24, 2015 |
SYSTEM AND METHOD FOR FORMING ELONGATED PERFORATIONS IN AN INNER
BARREL SECTION OF AN ENGINE
Abstract
Certain embodiments of the present disclosure provide an
acoustic inlet barrel of an engine. The acoustic inlet barrel may
include an inner barrel configured to provide a boundary for
directing airflow through the engine. The inner barrel may include
an inner face sheet separated from an outer face sheet by an
acoustic core. The inner barrel may include a plurality of
elongated, non-circular perforations formed through the inner face
sheet.
Inventors: |
Lauder; Arnold J.;
(Winnipeg, CA) ; Gabriel; Mark F.; (Renton,
WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THE BOEING COMPANY |
Chicago |
IL |
US |
|
|
Assignee: |
THE BOEING COMPANY
Chicago
IL
|
Family ID: |
54141642 |
Appl. No.: |
14/716402 |
Filed: |
May 19, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14012243 |
Aug 28, 2013 |
|
|
|
14716402 |
|
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|
Current U.S.
Class: |
181/214 ;
29/890.08; 408/131; 409/143 |
Current CPC
Class: |
B23C 3/00 20130101; B32B
2262/103 20130101; B32B 15/04 20130101; B23C 2215/04 20130101; B23B
39/14 20130101; B32B 2262/101 20130101; B23B 39/20 20130101; Y10T
29/49398 20150115; B32B 27/20 20130101; B32B 2307/102 20130101;
B25J 11/005 20130101; B23C 2220/24 20130101; B23C 3/02 20130101;
B32B 27/06 20130101; B23B 39/24 20130101; B23B 2270/20 20130101;
G10K 11/172 20130101; F02C 7/045 20130101; B23B 2226/27 20130101;
Y02T 50/60 20130101; Y10T 409/304424 20150115; B23B 2215/04
20130101; B32B 2262/0269 20130101; F01N 13/007 20130101; B32B
2605/18 20130101; Y10T 408/6764 20150115; B32B 15/20 20130101; B23C
2226/27 20130101; B23B 2270/32 20130101; B23C 2270/18 20130101;
B32B 3/12 20130101; Y02T 50/672 20130101; B23C 3/28 20130101 |
International
Class: |
F01N 13/00 20060101
F01N013/00; B23B 39/24 20060101 B23B039/24; B23C 1/12 20060101
B23C001/12; B23B 39/14 20060101 B23B039/14 |
Claims
1. An acoustic inlet barrel of an engine, the acoustic inlet barrel
comprising: an inner barrel configured to provide a boundary for
directing airflow through the engine, the inner barrel comprising
an inner face sheet separated from an outer face sheet by an
acoustic core, wherein the inner face sheet comprises a plurality
of elongated, non-circular perforations.
2. The acoustic inlet barrel of claim 1, wherein each of the
perforations is elongated with respect to a longitudinal axis.
3. The acoustic inlet barrel of claim 2, wherein the longitudinal
axis aligns with a flow contour line of the airflow through the
engine.
4. The acoustic inlet barrel of claim 1, wherein at least one of
the perforations is shaped as an elongated slot.
5. The acoustic inlet barrel of claim 1, wherein at least one of
the perforations has a teardrop shape.
6. The acoustic inlet barrel of claim 1, wherein at least one of
the perforations has an elliptical shape.
7. The acoustic inlet barrel of claim 1, wherein at least one of
the perforations has a dogbone shape.
8. A method of forming a component of an engine, the method
comprising: sandwiching an acoustic core between an inner section
and an outer section of the component; and forming a plurality of
elongated, non-circular perforations in at least a portion of the
inner section.
9. The method of claim 8, wherein the forming operation comprises
using at least one robotic forming unit to elongate each of the
perforations with respect to a longitudinal axis.
10. The method of claim 9, wherein the longitudinal axis aligns
with a flow contour line of the airflow through the engine.
11. The method of claim 8, wherein the forming operation comprises
forming at least one of the perforations as an elongated slot.
12. The method of claim 8, wherein the forming operation comprises
forming at least one of the perforations as one or more of a
teardrop shape, an elliptical shape, or a dogbone shape.
13. A forming system, comprising: at least one robotic forming unit
including at least one end effector positioned inside a barrel
section configured as a composite sandwich structure having an
inner face sheet, wherein the at least one robotic forming unit is
operable to form a plurality of elongated, non-circular
perforations into the inner face sheet using the at least one end
effector to provide a predetermined percent-open-area of the inner
face sheet.
14. The forming system of claim 13, wherein each of the
perforations is elongated with respect to a longitudinal axis.
15. The forming system of claim 14, wherein the longitudinal axis
aligns with a flow contour line of airflow through an engine.
16. The forming system of claim 13, wherein at least one of the
perforations is shaped as an elongated slot.
17. The forming system of claim 13, wherein at least one of the
perforations has a teardrop shape.
18. The forming system of claim 13, wherein at least one of the
perforations has an elliptical shape.
19. The forming system of claim 13, wherein at least one of the
perforations has a dogbone shape.
20. The forming system of claim 13, wherein the at least one
robotic forming unit is configured to: index a pattern of
perforations to one or more cell walls of a honeycomb core of the
composite sandwich structure; form the pattern of perforations in
the inner face sheet such that the perforations are located at a
spaced distance from the cell walls of the honeycomb core; and form
the perforations such that the percent-open-area in one section of
the inner face sheet is different than the percent-open-area in
another section of the inner face sheet.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 14/012,243, entitled "System and Method for
Forming Perforations in a Barrel Section," filed Aug. 28, 2013,
which is hereby incorporated by reference in its entirety.
FIELD OF THE DISCLOSURE
[0002] Embodiments of the present disclosure generally relate to
production of acoustic treatment of structures and, more
particularly, to the forming of acoustic perforations in an engine
inlet barrel section.
BACKGROUND
[0003] Commercial airliners are required to meet certain noise
standards such as during takeoff and landing. A large portion of
the noise produced by a commercial airliner during takeoff and
landing is generated by gas turbine engines commonly used on
airliners. Known methods for reducing the noise level of a gas
turbine engine include acoustically treating the engine inlet of
the engine nacelle. In this regard, the inner barrel section of a
gas turbine engine inlet may be provided with a plurality of
relatively small perforations formed in the walls of the inner
barrel section. The perforations absorb some of the noise that is
generated by fan blades rotating at high speed at the engine inlet,
and thereby reduce the overall noise output of the gas turbine
engine.
[0004] Conventional methods for forming perforations in acoustic
structures such as the barrel section include forming the inner
wall of the barrel section as a separate component, followed by
forming the perforations in the inner wall. The inner wall may then
be assembled with other components that make up the barrel section,
which is then assembled with the nacelle of the gas turbine engine.
Unfortunately, such conventional methods for forming acoustic
structures include operations that may result in the blockage of
some of the perforations after the perforations have been
formed.
[0005] Conventional methods for forming acoustic structures may
also result in missing perforations. Such blocked perforations or
missing perforations may reduce the percent-open-area (POA) of the
inner wall (e.g., the total area of the perforations as a
percentage of the surface area of the inner wall) which is a
characteristic of acoustic structures for measuring their overall
effectiveness in absorbing or attenuating noise. Furthermore,
conventional methods of forming perforations in acoustic structures
are time-consuming processes that add to the production schedule
and cost.
[0006] Additionally, known systems and methods for forming acoustic
structures include forming numerous round holes within an inner
barrel. In general, the formation of round holes is simple and
effective. However, round holes within an inner barrel may not
exhibit acoustic properties that are sufficient to efficiently
reduce sound within a structure, device, or component. For example,
a pattern of circular holes within the inlet barrel typically
depends on a size and nature of the components within an acoustic
inlet barrel. For each different acoustic inlet barrel, a unique
pattern of circular holes is first determined and then formed. As
such, a formed acoustic inlet barrel is typically designed for a
particular structure and may not be substituted for another
structure having different properties.
[0007] A need exists for a system and method for forming
perforations in an acoustic structure that minimizes, eliminates,
or otherwise reduces the occurrence of blocked or missing
perforations, and which may be performed in a timely and
cost-effective manner. Further, a need exists for a system and
method for efficiently forming perforations within an acoustic
structure. Moreover, a need exists for a system and method of
manufacturing a complex geometric pattern of perforations on an
acoustic inlet barrel of an aircraft engine, or other such
structure.
SUMMARY OF THE DISCLOSURE
[0008] The above-noted needs associated with forming perforations
in an acoustic structure such as an engine inlet are specifically
addressed and alleviated by the present disclosure which provides a
forming system that may include a plurality of robotic drilling
units. Each one of the robotic drilling units may include a drill
end effector positioned inside a barrel section of an engine inlet.
The barrel section may be configured as a composite sandwich
structure having an inner face sheet. The robotic drilling units
may be operable in synchronized movement with one another to drill
a plurality of perforations into the inner face sheet using the
drill end effectors in a manner providing a predetermined
percent-open-area of the inner face sheet.
[0009] Also disclosed is a method of fabricating an engine inlet.
The method may include providing an engine inlet inner barrel
section configured as a composite sandwich structure having an
inner face sheet, a core, and an outer face sheet. The method may
further include robotically drilling a plurality of perforations in
the inner face sheet after final cure of the composite sandwich
structure. The method may additionally include forming the
plurality of perforations in a quantity providing a predetermined
percent-open-area of the inner face sheet.
[0010] In a further embodiment, disclosed is a method of
fabricating an engine inlet including the step of providing an
engine inlet inner barrel section configured as a one-piece
composite sandwich structure having an inner face sheet, an outer
face sheet, and a honeycomb core. The composite sandwich structure
may be formed in a single stage cure wherein the inner face sheet,
the core, and the outer face sheet may be co-cured and/or co-bonded
in a single operation. The method may include drilling, using a
plurality of robotic drilling units, a plurality of perforations in
the inner face sheet after final cure of the composite sandwich
structure. The method may further include operating the plurality
of robotic drilling units in synchronized movement with one another
to simultaneously drill the plurality of perforations. The method
may also include forming the plurality of perforations in a
quantity providing a predetermined percent-open-area of the inner
face sheet.
[0011] Certain embodiments of the present disclosure provide an
engine component, such as an acoustic inlet barrel of an engine.
The acoustic inlet barrel may include an inner barrel configured to
provide a boundary for directing airflow through the engine. The
inner barrel may include an inner face sheet separated from an
outer face sheet by an acoustic core. The inner face sheet may
include a plurality of elongated, non-circular perforations.
Optionally, embodiments of the present disclosure may be used with
various other components of an engine, such as a translating
sleeve, inner walls, and the like.
[0012] Each of the perforations may be elongated with respect to a
longitudinal axis. The longitudinal axis may align with a flow
contour line of the airflow through the engine.
[0013] At least one of the perforations may be shaped as an
elongated slot. In at least one other embodiment, one or more of
the perforations may be shaped as a teardrop, ellipse, dogbone, or
the like.
[0014] Certain embodiments of the present disclosure provide a
method of forming an acoustic inlet barrel of an engine. The method
may include sandwiching an acoustic core between an inner barrel
and an outer barrel, and forming a plurality of elongated,
non-circular perforations in at least a portion of the inner
barrel. The forming operation may include using at least one
robotic forming unit to elongate each of the perforations with
respect to a longitudinal axis.
[0015] Certain embodiments of the present disclosure provide a
method of forming a component of an engine, such as an acoustic
inlet barrel of the engine. The method may include sandwiching an
acoustic core between an inner section and an outer section of the
component, and forming a plurality of elongated, non-circular
perforations in at least a portion of the inner section.
[0016] Certain embodiments of the present disclosure provide a
forming system that may include at least one robotic forming unit
including at least one end effector positioned inside a barrel
section configured as a composite sandwich structure having an
inner face sheet. The robotic forming unit(s) is operable to form a
plurality of elongated, non-circular perforations into the inner
face sheet using the end effector(s) to provide a predetermined
percent-open-area of the inner face sheet. The robotic forming
unit(s) may be further configured to index a pattern of
perforations to one or more cell walls of a honeycomb core of the
composite sandwich structure, form the hole pattern in the inner
face sheet such that the perforations are located at a spaced
distance from the cell walls of the honeycomb core, and/or form the
perforations such that the percent-open-area in one section of the
inner face sheet is different than the percent-open-area in another
section of the inner face sheet.
[0017] The features, functions and advantages that have been
discussed can be achieved independently in various embodiments of
the present disclosure or may be combined in yet other embodiments,
further details of which can be seen with reference to the
following description and drawings below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] These and other features of the present disclosure will
become more apparent upon reference to the drawings wherein like
numbers refer to like parts throughout and wherein:
[0019] FIG. 1 is a perspective illustration of an aircraft.
[0020] FIG. 2 is a perspective illustration of a nacelle of a gas
turbine engine of the aircraft of FIG. 1.
[0021] FIG. 3 is a perspective illustration of an inner barrel
section of an engine inlet of the gas turbine engine of FIG. 2.
[0022] FIG. 4 is a cross-sectional illustration of a leading edge
of the engine inlet of the gas turbine engine of FIG. 2.
[0023] FIG. 5 is a perspective illustration of an embodiment of a
forming system for forming perforations in a barrel section.
[0024] FIG. 6 is a perspective illustration of the forming system
with the barrel section shown in phantom lines to illustrate a
plurality of robotic drilling units of the forming system.
[0025] FIG. 7 is a side view of the forming system.
[0026] FIG. 8 is the top view of the forming system.
[0027] FIG. 9 is a side view of one of the robotic drilling units
forming a perforation pattern along an inner face sheet of the
inner barrel section.
[0028] FIG. 10 is a perspective illustration of a drill end
effector forming a perforation in an inner face sheet of a
composite sandwich structure of the inner barrel section.
[0029] FIG. 11 is a cross sectional illustration taken along line
11 of FIG. 10 and illustrating a drill bit of the drill end
effector drilling a perforation in the inner face sheet of the
composite sandwich structure.
[0030] FIG. 12 is a block diagram of an embodiment of the forming
system.
[0031] FIG. 13 is an illustration of a flow chart including one or
more operations that may be implemented in a method of fabricating
an engine inlet.
[0032] FIG. 14 illustrates an interior face view of an inner face
sheet having a plurality of elongated perforations, according to an
embodiment of the present disclosure.
[0033] FIG. 15 illustrates an interior face view of an inner face
sheet having a plurality of elongated perforations, according to an
embodiment of the present disclosure.
[0034] FIG. 16 illustrates an interior face view of an inner face
sheet having a plurality of elongated perforations, according to an
embodiment of the present disclosure.
[0035] FIG. 17 illustrates a perspective interior view of an
acoustic inlet barrel, according to an embodiment of the present
disclosure.
[0036] FIG. 18 illustrates an interior face view of a perforation
formed in an inner face sheet, according to an embodiment of the
present disclosure.
[0037] FIG. 19 illustrates an interior face view of a perforation
formed in an inner face sheet, according to an embodiment of the
present disclosure.
[0038] FIG. 20 illustrates an interior face view of a perforation
formed in an inner face sheet, according to an embodiment of the
present disclosure.
[0039] FIG. 21 illustrates an interior face view of a perforation
formed in an inner face sheet, according to an embodiment of the
present disclosure.
[0040] FIG. 22 is a flow diagram of an aircraft manufacturing and
service methodology.
[0041] FIG. 23 is a block diagram of an aircraft.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0042] The foregoing summary, as well as the following detailed
description of certain embodiments will be better understood when
read in conjunction with the appended drawings. As used herein, an
element or step recited in the singular and preceded by the word
"a" or "an" should be understood as not necessarily excluding the
plural of the elements or steps. Further, references to "one
embodiment" are not intended to be interpreted as excluding the
existence of additional embodiments that also incorporate the
recited features. Moreover, unless explicitly stated to the
contrary, embodiments "comprising" or "having" an element or a
plurality of elements having a particular property may include
additional elements not having that property.
[0043] Certain embodiments of the present disclosure provide
systems and methods for forming noise abatement structures having
non-circular perforations, such as slots, for example. The
non-circular perforations may be formed through use of a plurality
of robots and/or drill or mill end effectors. In at least one
embodiment, the non-circular perforations may be formed into an
inner face sheet of an acoustically treated structure, such as an
acoustic inlet barrel of an aircraft engine. Certain embodiments of
the present disclosure provide systems and methods for creating a
plurality of non-circular perforations on a structure having a
complex curvature, such as an acoustically-treated inner barrel of
an acoustic inlet barrel of an aircraft engine.
[0044] A face sheet may include a single ply of material, or
multiple plies of material. For example, the face sheet may include
multiple sheets or plies of material that are laminated
together.
[0045] Certain embodiments of the present disclosure provide an
acoustic engine inlet inner barrel that may include an inner
portion having a plurality of perforations. Each of the
perforations may be elongated along an axis. Each perforation may
be formed as a slot, tear drop, ellipse, diamond, or various other
elongated shapes. The axis may be substantially parallel to a flow
contour line, which may be uniform or non-uniform. The inner barrel
may be integrally formed as a single piece.
[0046] Certain embodiments of the present disclosure provide a
method of creating perforations on an interior of a curved
structure that may include loading a program into one or more
robots to carve non-circular perforations. Each of the non-circular
perforations may be elongated in a first direction. The direction
may be parallel to flow contours along a surface of the curved
structure.
[0047] Embodiments of the present disclosure provide structures
having improved acoustic performance and aerodynamics (for example,
the non-circular holes may be aligned with airflow that may not be
perfectly straight). Further, embodiments of the present disclosure
provide efficient manufacturing systems and methods of forming
perforations in composite material. Further, embodiments of the
present disclosure provide systems and methods of forming
non-rectilinear patters of perforations in engine inlet
barrels.
[0048] Referring now to the drawings wherein the showings are for
purposes of illustrating various embodiments of the present
disclosure, shown in FIG. 1 is a perspective illustration of an
aircraft 100. The aircraft 100 may include a fuselage 102 extending
from a nose to an empennage 104. The empennage 104 may include one
or more tail surfaces for directional control of the aircraft 100.
The aircraft 100 may include a pair of wings 106 extending
outwardly from the fuselage 102.
[0049] In FIG. 1, the aircraft 100 may include one or more
propulsion units which, in an embodiment, may be supported by the
wings 106. Each one of the propulsion units may be configured as a
gas turbine engine 108 having a core engine (not shown) surrounded
by a nacelle 110. The nacelle 110 may include an engine inlet 114
and a fan cowl 118 surrounding one or more fans (not shown) mounted
on a forward end (not shown) of the core engine. The nacelle 110
may have an exhaust nozzle 112 (e.g., a primary exhaust nozzle and
a fan nozzle) at an aft end (not shown) of the gas turbine engine
108.
[0050] FIG. 2 illustrates an embodiment of a gas turbine engine 108
having an engine inlet 114. The engine inlet 114 may include a
leading edge 116 and an inner barrel section 120 located aft of the
leading edge 116 of the engine inlet 114. The inner barrel section
120 may provide a boundary surface or wall for directing airflow
(not shown) entering the engine inlet 114 and passing through the
gas turbine engine 108. The inner barrel section 120 may be located
in relatively close proximity to one or more fans (not shown). In
this regard, the inner barrel section 120 may also be configured to
serve as an acoustic structure having a plurality of perforations
in an inner face sheet of the inner barrel section 120 for
absorbing noise generated by the rotating fans and/or noise
generated by the airflow entering the engine inlet 114 and passing
through the gas turbine engine 108.
[0051] As described below, the total area of the perforations in
the inner face sheet may be expressed as a percent-open-area which
represents the total area of the perforations as a percentage of
the surface area of the inner face sheet. The percent-open-area may
be a characteristic for measuring the overall effectiveness or
acoustic-attenuating capability of the inner barrel section 120.
During the design and/or development of the aircraft 100, a
predetermined percent-open-area may be selected for the inner
barrel section 120 to meet acoustic performance requirements of the
engine inlet 114.
[0052] FIG. 3 is a perspective illustration of an embodiment of an
inner barrel section 120 of an engine inlet 114. In the embodiment
shown, the barrel section 120 may have a diameter (not shown) of up
to 5-8 feet or larger, and a length (not shown) extending from an
aft edge 126 to a forward edge 124 of up to 2-3 feet or longer.
However, the barrel section 120 may be provided in any size, shape,
and configuration, without limitation. The inner barrel section 120
may be formed as a composite sandwich structure 122 having an inner
face sheet 134 and an outer face sheet 132 separated by a core 128.
The inner face sheet 134 and/or the outer face sheet 132 may be
formed of composite material including fiber-reinforced polymeric
matrix material such as graphite-epoxy, fiberglass-epoxy, or other
composite material. Alternatively, the inner face sheet 134 and/or
the outer face sheet 132 may be formed of metallic material such as
titanium, steel, or other metallic materials or combinations of
materials. The core 128 may include a honeycomb core having a
plurality of cells 130 oriented generally transverse to the inner
face sheet 134 and outer face sheet 132. The core 128 may be formed
of metallic material and/or non-metallic material and may include
aluminum, titanium, aramid, fiberglass, or other core
materials.
[0053] In an embodiment, the engine inlet 114 may include a
one-piece inner barrel section 120. The inner barrel section 120
may be fabricated from raw materials (not shown) and assembled and
cured in one or more stages. For example, the inner face sheet 134
and the outer face sheet 132 may be separately formed by laying up
dry fiber fabric (not shown) or resin-impregnated ply material (for
example, pre-preg) on separate layup mandrels (not shown) and
separately cured, followed by bonding the inner face sheet 134 and
the outer face sheet 132 to the core 128. Alternatively, the inner
barrel section 120 may be fabricated in a single-stage cure process
in which the inner face sheet 134 may be laid up on a layup mandrel
(not shown), after which the core 128 may be laid up over the inner
face sheet 134, followed by laying up the outer face sheet 132 over
the core 128. The layup assembly (not shown) may be cured in a
single stage, after which a forming system disclosed herein may be
implemented for forming perforations in the inner face sheet
134.
[0054] In at least one embodiment, the forming system may be
implemented for forming a plurality of perforations in the inner
face sheet 134 of the assembled barrel section 120. The
perforations may be non-circular. For example, the perforations may
be formed as elongated structures, such as slots, elliptical
openings, diamond-shaped openings, dogbone-shaped openings, and/or
the like. In at least one embodiment, the forming system may
include a plurality of robotic drilling units positioned inside the
barrel section 120 for robotically drilling a plurality of the
perforations in the inner face sheet 134 after final cure of the
composite sandwich structure 122. The perforations may be formed in
a size and quantity to provide a predetermined percent-open-area
for the inner barrel section 120 to allow the inner barrel section
120 to meet acoustic performance requirements of the engine inlet
114.
[0055] In FIG. 3, the inner barrel section 120 may include a
unitary structure having a closed shape with a generally
cylindrical configuration. However, in at least one other
embodiment, the inner barrel section 120 may be formed as multiple
segments (not shown) assembled together to form a closed shape. The
inner barrel section 120 may be provided in a contoured
cross-sectional shape (not shown) to promote airflow through the
gas turbine engine 108. In this regard, when viewed along a
circumferential direction, the inner barrel section 120 may have a
cross section that may be complexly curved and may be formed
complementary to the shape of the engine inlet 114 leading edge 116
at a forward edge 124 of the inner barrel section 120, and
complementary to the shape of the interior nacelle surfaces (not
shown) aft of the inner barrel section 120. However, the inner
barrel section 120 may be provided in any shape including a simple
cylindrical shape and/or a conical shape.
[0056] FIG. 4 is a cross-sectional illustration of the leading edge
116 of the engine inlet 114 showing the composite sandwich
construction including the circumferential inner face sheet 134,
the circumferential outer face sheet 132, and the core 128
separating the inner face sheet 134 and outer face sheet 132 of the
barrel section 120. The forward edge 124 of the inner barrel
section 120 may be coupled to or may interface with the engine
inlet 114 leading edge 116. The aft edge 126 of the inner barrel
section 120 may be coupled to or may interface with the nacelle
interior (not shown). In the embodiment shown, the inner face sheet
134, the core 128, and the outer face sheet 132 may have a
complexly-curved cross sectional shape to promote efficient airflow
through the nacelle 110.
[0057] FIG. 5 is an illustration of an embodiment of a forming
system 200 as may be implemented for forming perforations in a
barrel section, such as the inner barrel section 120 of the engine
inlet 114 of the gas turbine engine 108 (shown in FIG. 3). However,
the forming system 200 may be implemented for forming perforations
in any type of barrel structure for any application, without
limitation. For example, the forming system 200 may be implemented
for forming perforations in a barrel section of any one of a
variety of different types of commercial, civilian, and military
aircraft. Furthermore, the forming system 200 may be implemented
for forming perforations in the barrel section of a gas turbine
engine of rotorcraft, hovercraft, or in any other vehicular or
non-vehicular application in which a predetermined quantity of
acoustic perforations are desired for acoustic attenuating
purposes.
[0058] In FIG. 5, the forming system 200 is shown mounted within an
interior of the barrel section 120. The forming system 200 may
include robotic forming units 208 that are configured to form
perforations in a barrel section 120 according to embodiments of
the present disclosure. For example, the robotic forming units 208
may be configured to provide a predetermined percent-open-area of
the inner face sheet 134 of the barrel section 120. As indicated
above, the predetermined percent-open-area 144 may be determined
during the design and/or development of the aircraft 100 (shown in
FIG. 1) to meet acoustic performance requirements of the engine
inlet 114. The forming system 200 is configured to consistently
form perforations in the inner face sheet 134 of the composite
sandwich structure 122 barrel sections 120 to provide a
predetermined percent-open-area in the inner face sheet 134. In
this regard, the forming system 200 advantageously overcomes the
drawbacks associated with conventional methods for forming
perforations in conventional inner barrel sections such as the
above-mentioned drawbacks associated with blocked perforations due
to subsequent processing of a conventional inner barrel section in
a conventional multi-stage forming process, and/or due to missing
perforations (not shown) during conventional perforating of the
inner skin of a conventional inner barrel section. Such blocked
perforations or missing perforations may reduce the predetermined
percent-open-area of the inner skin of the conventional inner
barrel section which may otherwise reduce the acoustic performance
of the engine inlet 114.
[0059] In FIG. 5, a plurality of robotic forming units 208 (for
example, two robotic forming units 208, three robotic forming units
208, etc.) may be supported on a system base 202. Each one of the
robotic forming units 208 may include an end effector 234, such as
a drill end effector, a mill end effector, or the like. In at least
one embodiment, the system base 202 may include a relatively rigid
structure and a tooling fixture, a shop floor, or a table
configured to support the plurality of robotic forming units 208.
In addition, the system base 202 may be configured to support the
barrel section 120. However, the forming system 200 may be provided
in another embodiment in which the plurality of robotic forming
units 208 are supported by a structure that is located separate
from the barrel section 120. For example, the plurality of robotic
forming units 208 may be suspended over the inner barrel section
120 such as by an overhead fixture (not shown) in a manner such
that the end effectors 234 may be positioned within the interior of
the barrel section 120, and/or the plurality of robotic forming
units 208 may be mounted inside or outside of the barrel section
120.
[0060] FIG. 6 is a perspective illustration of the plurality of
robotic forming units 208 positioned on the system base 202 and
mounted within relatively close proximity to one another such that
the barrel section 120 circumscribes the plurality of robotic
forming units 208 when the barrel section 120 is mounted to the
system base 202. Although four (4) robotic forming units 208 are
shown, any number may be provided. In an embodiment, the robotic
forming units 208 may be mounted in an array. For example, each one
of the robotic forming units 208 may include a forming unit base
212 (such as shown in FIG. 7). The forming unit bases 212 may be
mounted to the system base 202 in a circular array 206 (as shown in
FIG. 8) such that when the barrel section 120 is mounted to the
system base 202, each one of the forming unit bases 212 is
positioned at substantially the same distance from the inner face
sheet 134 of the barrel section 120.
[0061] FIG. 7 is a side view of an embodiment of the forming system
200. The barrel section 120, shown in phantom lines, may be
supported on one fixture 204 or multiple fixtures 204. The fixtures
204 may include spacers sized and configured to position the barrel
section 120 at a vertical location that is complementary to the
movement capability of the end effectors 234 of the robotic forming
units 208. In this regard, the fixtures 204 may be configured such
that the end effectors 234 may form perforations (such elongated,
non-circular perforations) in the inner face sheet 134 of the
barrel section 120 at any vertical location between the forward
edge 124 of the barrel section 120 and the aft edge 126 of the
barrel section 120. Each of the fixtures 204 may include a rigid
material and may be configured as simple blocks (not shown) formed
of metallic or polymeric material and which may be fixedly coupled
to the system base 202. The fixtures 204 may extend vertically
along any portion of the height of the barrel section and
horizontally along any portion of the circumference of the barrel
section 120.
[0062] FIG. 8 is a top view of the forming system 200 illustrating
an arrangement of the robotic forming units 208. Each one of the
robotic forming units 208 may include a robotic arm assembly 210
having an end effector 234 mounted on an end of the robotic arm
assembly 210. The robotic forming units 208 may be mounted such
that forming unit bases 212 are positioned adjacent to a center of
the array of the robotic forming units 208. In at least one
embodiment, the forming system 200 may include a single robotic
forming unit 208 or a plurality of robotic forming units 208. For
example, the forming system 200 may include two (2) or more robotic
forming units 208 having forming unit bases 212 which may be
arranged at a predetermined spacing relative to one another, such
as a substantially equiangular spacing relative to one another.
[0063] Referring still to FIG. 8, the plurality of robotic forming
units 208 may be configured (for example, programmed) to drill
perforations (such as elongated, non-circular perforations) within
substantially equivalent arc segments 142 of the barrel section
120. For example, for the embodiment shown, the plurality of
robotic forming units 208 may include four (4) robotic forming
units 208. The forming unit bases 212 may be arranged such that the
forming unit bases 212 are positioned at an angular spacing of
approximately ninety degrees relative to one another. In at least
one embodiment, each one of the robotic forming units 208 may be
configured to form perforations within an approximate ninety-degree
arc segment 142 of the barrel section 120. However, the robotic
forming units 208 may be positioned at any location relative to one
another and may be configured to form perforations at any
circumstantial location or any vertical location of the barrel
section 120.
[0064] In FIG. 8, the end effector 234 of each one of the robotic
forming units 208 may be oriented generally radially outwardly away
from the forming unit base 212. The forming unit bases 212 may be
positioned to provide space for movement of the robotic arm
assemblies 210 during operation of the forming system 200. In this
regard, the robotic forming units 208 are simultaneously operable
in synchronized movement with one another in a manner allowing the
end effectors 234 to simultaneously form a plurality of
perforations in the barrel section 120. The robotic forming units
208 may be programmed to avoid collisions with one another and with
the barrel section 120 during the synchronized movement with one
another.
[0065] FIG. 9 is a side view of one of the robotic forming units
208 showing the barrel section 120 supported on fixtures 204 and
illustrating a forming bit 236 of one of the end effectors 234
forming perforations 136 in a predetermined perforation pattern 140
along the inner face sheet 134 of the inner barrel section 120. In
this regard, in at least one embodiment, each one of the robotic
forming units 208 may be indexed to the system base 202. The barrel
section 120 may also be indexed to the system base 202 such as with
fixtures 204 to provide a means for the end effector 234 to form
perforations 136 within a relatively small positional tolerance
relative to a circumferential direction (not shown) of the barrel
section 120 and relative to an axial direction (not shown) of the
barrel section 120. However, the barrel section 120 and the robotic
forming units 208 may be indexed relative to one another by other
means, and are not necessarily limited to being indexed to the
system base 202.
[0066] In FIG. 9, the robotic forming units 208 may be operated in
a manner to form the perforations 136 in the inner face sheet 134
such that a percent-open-area 144 in one section 148 of the inner
face sheet 134 is different than the percent-open-area 144 in
another section 150 of the inner face sheet 134. In this regard,
the robotic forming units 208 may be programmed to form
perforations 136 to provide a greater percent-open-area 144 in a
first section 148 of the inner face sheet 134 relative to drilling
perforations 136 to provide a lower percent-open-area 144 in a
second section 150 of the inner face sheet 134. For example, the
second section 150 with a smaller percent-open-area 144 may be
located adjacent to a forward edge 124 and/or an aft edge 126 of
the barrel section 120, and the first section 148 with a larger
percent-open-area 144 may be located in an interior region (not
shown) of the inner barrel section 120 between the forward edge 124
and the aft edge 126. However, the robotic forming 208 units may
form the perforations 136 such that the percent-open-area 144 in
the inner face sheet 134 is different at different circumferential
sections (not shown) of the barrel section 120, or the
percent-open-area 144 of the inner barrel section 120 may vary in a
different manner than the above-noted embodiments.
[0067] In FIG. 9, one or more of the robotic forming units 208 may
have a six-axis robotic arm assembly 210 which may allow for
accurately positioning the end effector 234 at any desired location
and orientation along the inner face sheet 134. As the end effector
234 is positioned and oriented at a desired location of a
perforation 136, the end effector 234 may be moved axially to drive
the forming bit 236 into the inner face sheet 134 to form a
perforation 136. After an initial opening is formed, the forming
bit 236 may radially shift through a radial arc to form the
elongated perforation 136. In this manner, the forming bit 236 may
be a drill or milling bit that may be configured to rotate about a
central longitudinal axis and radially shift in order to form the
elongated perforation 136. In at least one other embodiment, the
forming bit 236 may be sized and shaped as a desired shape of an
elongated perforation 136 and puncture the inner face sheet 134 to
form the elongated perforation 136. Alternatively, the end effector
234 may be positioned at a desired location of a perforation 136 on
the inner face sheet 134, and the end effector 234 may axially
drive the forming bit 236 along a direction of the forming bit axis
238 to drill the perforation 136 in the inner face sheet 134. In at
least one embodiment, the six-axis robotic arm assembly 210 may
include a first arm 220 which may be attached to the forming unit
base 212 at a shoulder joint 216. The first arm 220 may be attached
to a second arm 226 at an elbow joint 222. The second arm 226 may
be attached to the end effector 234 at a wrist joint 230.
[0068] In FIG. 9, the forming unit base 212 may be configured to
rotate about a vertical base axis 214 relative to the system base
202. The first arm 220 may be configured to rotate about a shoulder
axis 218 of the shoulder joint 216 coupling the first arm 220 to
the forming unit base 212. The second arm 226 may be configured to
rotate about an elbow axis 224 of the elbow joint 222 coupling the
second arm 226 to the first arm 220. A portion of the second arm
226 may also be configured to swivel about a second arm axis 228
extending along a direction from the elbow joint 222 to the wrist
joint 230. The end effector 234 may be configured to rotate about a
wrist axis 232 of the wrist joint 230. In addition, the end
effector 234 may be configured to rotate about an end effector axis
235 which may be generally parallel to the forming bit axis 238. In
an optional embodiment, the end effector 234 may be configured to
linearly translate the forming bit 236 along a forming bit axis 238
such as when drilling a portion of perforation 136 in the inner
face sheet 134.
[0069] In FIG. 9, the robotic arm assembly 210 is shown in a
six-axis embodiment. However, the robotic arm assembly 210 may be
provided in alternative arrangements. For example, the robotic arm
assembly 210 may be provided in a 3-axis embodiment, a 4-axis
embodiment, or a 5-axis embodiment. In addition, the robotic arm
assembly 210 may be provided in an embodiment having more than six
(6) axes. Furthermore, the robotic arm assembly 210 may be
configured as a motion control system (not shown), a rigid frame
(not shown) having linear axes along which the end effector is
movable, or any other type of motion control device for controlling
an end effector 234 for forming the perforations 136. In addition,
each robotic arm assembly 210 may include more than one end
effector 234. Furthermore, each end effector 234 may have more than
one forming bit 236 for simultaneously forming perforations
136.
[0070] FIG. 10 shows an end effector 234 forming a perforation 136
in the inner face sheet 134 of a composite sandwich structure 122
of the inner barrel section 120. Advantageously, the forming system
200 is configured to accurately and rapidly place the end effector
234 for forming perforations 136 in a predetermined perforation
pattern, such as the pattern 140 shown in FIG. 9. For example, in
at least one embodiment, each one of the end effectors 234 of a
robotic forming unit 208 may be configured to form up to three (3)
or more perforations 136 per second, per end effector 234. In at
least one embodiment, the end effector 234 may be provided with a
forming bit 236 configured to form elongated, non-circular acoustic
perforations 136 having a length of approximately 0.2 inch, 0.3
inch, 0.4 inch, or 0.5 inch. Optionally, the perforations 136 may
be longer or shorter than noted.
[0071] As shown, the end effector 234 may initially form a portion
of the perforation 136 through a drilling operation. For example,
the end effector 234 may be rotated about its central longitudinal
axis and urged into the inner face sheet 134. After the initial
portion is formed through the drilling operation, the forming
system 200 may be rotated in a radial sweeping direction A to
elongate the perforation 136 starting from the initial drilled
opening to an end point, as determined by the forming program. In
at least one other embodiment, the forming system 200 may remain in
a fixed position, while the barrel section 120 is rotated about a
central axis relative to the forming system 200.
[0072] In at least one embodiment, for forming perforations 136 in
a composite inner face sheet 134, the end effector 234 may be
configured to drive the forming bit 236 at a feed rate of
approximately 20-60 inches per minute, and at rotational speeds of
between approximately 20,000 to 40,000 rpm, although larger or
smaller feed rates and larger or smaller rotational speeds may be
selected based on the material being drilled and the composition of
the forming bit 236. The forming bit 236 feed rate and the forming
bit 236 rotational speed may be controlled to minimize forming bit
236 wear, and such that the perforations 136 may meet tight
tolerances for size, shape, and other hole parameters.
Significantly, each robotic forming unit 208 may be configured to
quickly and accurately form perforation patterns at a relatively
small center-to-center positional tolerance (that is,
perforation-to-perforation) such as a center-to-center positional
tolerance of approximately 0.010 inch or less. However, the
center-to-center positional tolerance may be greater than 0.010
inch, such as up to approximately 0.050 inch or greater.
[0073] One or more of the end effectors 234 may include a vacuum
attachment 240 for removing debris (not shown) such as dust and
chips that may be generated as the perforations 136 are formed. The
vacuum attachment 240 may have a hollow (not shown) or open portion
(not shown) that may be positioned around the forming bit 236 and
may be placed adjacent to or in contact with the inner face sheet
134 when the forming bit 236 contacts the inner face sheet 134 and
forms a perforation 136. The vacuum attachment 240 may include a
vacuum port 242 for connection to a vacuum source (not shown) using
a vacuum hose (not shown) for drawing a vacuum 244 on the vacuum
attachment 240 for drawing debris (not shown) from the area
surrounding the perforation 136.
[0074] In at least one embodiment, the forming system 200 may be
provided with an automated bit changer (not shown) for changing the
forming bits 236 using robotic control. In this manner, worn
forming bits 236 may be replaced after forming a predetermined
quantity of perforations 136. For example, an automated bit changer
(not shown) may replace each forming bit 236 after forming anywhere
from approximately 1,000 to 30,000 perforations 136, although the
forming bits 236 may be replaced after forming a smaller or larger
quantity of perforations 136 than the above-noted range. Depending
upon the size (for example, diameter and height) of the inner
barrel section 120 and the total quantity of robotic forming units
208 that are used, each end effector 234 may undergo 1 to 20 or
more forming bit changes per barrel section 120, for example.
[0075] Referring again to FIG. 9, in at least one embodiment, the
end effectors 234 may be controlled to form perforations 136 in a
perforation pattern 140 of vertical rows along a height of the
barrel section 120. In this regard, each end effector 234 may form
a vertical row of perforations 136, and the end effector 234 may be
rotated about the vertical base axis 214 to allow the end effector
234 to form another vertical row of perforations 136 adjacent to
the previously-formed vertical row of perforations 136. The end
effectors 234 may also be controlled to form perforations 136 in
horizontal rows (not shown), or in any other direction or
combination of directions. As indicated above, the robotic arm
assemblies 210 may be operated in a synchronized manner such that
the end effectors 234 are maintained at a generally equiangular
spacing from one another during the simultaneous drilling of
perforations 136 in the inner face sheet 134 of the barrel section
120. For example, for a forming system 200 having four (4) robotic
forming units 208, the end effectors 234 may be maintained at an
angular separation of approximately ninety (90) degrees from each
other during the simultaneous forming of perforations 136 in the
inner face sheet 134.
[0076] FIG. 11 is a cross sectional view of a forming bit 236 of
the end effector 234 forming a perforation 136 in the inner face
sheet 134 of a composite sandwich structure 122. In an embodiment,
the end effector 234 may include a forming stop (not shown) to
control a depth 138 at which the forming bit 236 extends into the
composite sandwich structure 122, and minimize the depth 138 of the
forming bit 236 into the core 128 material. Furthermore, a forming
stop (not shown) may stabilize the end effector 234 when forming
the perforation 136 to prevent lateral movement of the forming bit
236 relative to the perforation 136, and which may advantageously
avoid a non-conformance regarding the positional tolerance, arcuate
tolerance, or other tolerance parameters of the perforation 136. In
at least one embodiment, each end effector 234 may include a
non-contact method of gauging the depth 138 at which each
perforation 136 is drilled such as by using a laser device (not
shown), an ultrasonic device (not shown), and other non-contact
device. The depth 138 of forming may also be controlled by a
controller (not shown) controlling the end effector 234.
[0077] FIG. 12 is a block diagram of an embodiment of a forming
system 200. The forming system 200 may include a plurality of
robotic forming units 208. Each one of the robotic forming units
208 may include a robotic arm assembly 210 as described above. An
end effector 234 may be coupled to the end of each one of the
robotic arm assemblies 210 of each robotic forming unit 208. The
robotic forming units 208 may be simultaneously operable in
synchronized movement with one another such that the end effectors
234 may simultaneously form a plurality of perforations 136 in the
barrel section 120.
[0078] In FIG. 12, the barrel section 120 may include an inner
barrel section 120 of an engine inlet 114 such as that of a gas
turbine engine 108 (shown in FIG. 3), as indicated above. In at
least one embodiment, the barrel section 120 may be formed as a
composite sandwich structure 122. The composite sandwich structure
122 may have an outer face sheet 132, a core 128, and an inner face
sheet 134 which may be assembled or bonded together to form a
one-piece engine inlet inner barrel section 120. The forming system
200 may rapidly and accurately form a plurality of perforations 136
in a predetermined perforation pattern of perforations 136 (FIG. 9)
in the inner face sheet 134 to provide a predetermined
percent-open-area 144 for the inner barrel section 120 to meet
acoustic performance requirements.
[0079] FIG. 13 is an illustration of a flow chart including one or
more operations that may be included in a method 300 of fabricating
an engine inlet 114 (FIG. 3). Step 302 of the method may include
providing a barrel section 120 (FIG. 3) such as an inner barrel
section 120 (FIG. 3) of an engine inlet 114 (FIG. 3). As indicated
above, the inner barrel section 120 (FIG. 3) may be provided as a
one-piece composite sandwich structure 122 (FIG. 3). In such a
composite sandwich structure 122 (FIG. 3), the inner face sheet 134
(FIG. 3) may be formed of composite material and the outer face
sheet 132 (FIG. 3) may be formed of composite material (for
example, fiber-reinforced polymeric matrix material). However, the
inner face sheet 134 (FIG. 3) and/or the outer face sheet 132 (FIG.
3) may be formed of metallic material, or a combination of metallic
material and non-metallic material.
[0080] As indicated above, the core 128 (FIG. 3) may include
honeycomb core formed of metallic material and/or non-metallic
material and may include aluminum, titanium, aramid, fiberglass, or
other core materials. The engine inlet 114 (FIG. 3) inner barrel
section 120 (FIG. 3) may be fabricated as a one-piece composite
sandwich structure 122 (FIG. 3) formed in a single-stage cure. As
described above, the barrel section 120 (FIG. 3) may be provided in
a single-stage cure wherein the inner face sheet 134 (FIG. 3), the
core 128 (FIG. 3), and the outer face sheet 132 (FIG. 3) may be
laid up on a layup mandrel, after which heat and/or pressure may be
applied to the layup (not shown) for a predetermined time for
curing in a single stage.
[0081] Step 304 of the method 300 of FIG. 13 may include mounting
and indexing the inner barrel section 120 (FIG. 7) to a system base
202 (FIG. 7). In this regard, the inner barrel section 120 (FIG. 7)
may be supported on a plurality of fixtures 204 (FIG. 7) which may
be mounted to the system base 202 (FIG. 7). The fixtures 204 (FIG.
7) may fixedly position the inner barrel section 120 (FIG. 7) on
the system base 202 (FIG. 7) which may comprise a table (not
shown), an assembly (not shown), or other relatively rigid
structure configured to support the inner barrel section 120 (FIG.
7) and prevent movement thereof during the drilling of the
perforations 136 (FIG. 9) in the inner barrel section 120 (FIG.
7).
[0082] As indicated above, the fixtures 204 may be positioned at
spaced intervals around a perimeter (not shown) of the inner barrel
section 120 such as along the aft edge 126 (FIG. 9) or forward edge
124 (FIG. 9) of the inner barrel section 120. The fixtures 204 may
include mechanical indexing features (not shown) to index the inner
barrel section 120 to the fixtures 204. A laser system (not shown)
may be implemented to aid in positioning the inner barrel section
120 relative to the fixtures 204. The inner barrel section 120 may
be mechanically coupled to the fixtures 204 to rigidly clamp the
inner barrel section 120 in position.
[0083] Step 306 of the method 300 of FIG. 13 may include indexing
the plurality of robotic forming units to the system base 202 (FIG.
7) as shown in FIG. 7. In at least one embodiment, each one of the
plurality of robotic forming units 208 (FIG. 7) may have a forming
unit base 212 (FIG. 7) that may be directly mounted to the system
base 202 and indexed to the system base 202 and/or to the fixtures
204 (FIG. 7) supporting the inner barrel section 120 (FIG. 7). For
example, the forming unit bases 212 of the robotic forming units
208 may be mounted to the system base 202 and may be located inside
the inner barrel section 120 as shown in FIG. 7. Alternatively, the
forming unit bases 212 may be located outside of the inner barrel
section 120 and the end effectors 234 (FIG. 7) of the robotic arm
assemblies 210 (FIG. 7) may extend inside the inner barrel section
120 to form the perforations 136 (FIG. 9). In a further embodiment,
the robotic forming units 208 may be supported by a structure (not
shown) that is located separate from the system base 202 and
separate from the barrel section 120. For example, the forming unit
bases 212 of the robotic forming units 208 may be mounted to an
overhead fixture (not shown) that may be indexed to the system base
202 and/or to the fixtures 204 supporting the inner barrel section
120. The end effectors 234 may extend inside the barrel section 120
to drill the perforations 136.
[0084] Step 308 of the method 300 of FIG. 13 may include
acoustically treating the engine inlet 114 (FIG. 9) by robotically
forming a plurality of perforations 136 (FIG. 9) into the inner
face sheet 134 (FIG. 9) of the composite sandwich structure 122
(FIG. 9) engine inlet 114 inner barrel section 120 (FIG. 9) such as
after final cure of the composite sandwich structure 122. For
example, the method 300 may include robotically forming the
plurality of perforations 136 in the inner barrel section 120 using
a plurality of the robotic forming units 208 (FIG. 9). The method
300 may include simultaneously forming the plurality of
perforations 136 in the inner face sheet 134 using the end
effectors 234 (FIG. 9) to provide a predetermined percent-open-area
144 of the inner face sheet 134. In an embodiment, each one of the
robotic forming units 208 may include a robotic arm assembly 210
(FIG. 9) configured as a three-axis, four-axis, five-axis, or
six-axis arm assembly respectively having three axes, four axe,
five axes, and six axes. The robotic arm assemblies 210 may be
programmed to move the end effectors 234 in a synchronized manner
relative to one another to form the perforations 136 at a
relatively rapid rate. For example, each one of the end effectors
234 may be configured to form 2-3 or more perforations 136 per
second.
[0085] The method 300 (FIG. 13) may include forming the
perforations 136 (FIG. 9) in a predetermined perforation pattern
140 (FIG. 9) in the engine inlet 114 (FIG. 9) inner barrel section
120 (FIG. 9) which may have a honeycomb core 128 (FIG. 11). The
robotic forming units 208 (FIG. 9) may be configured to control the
end effectors 234 (FIG. 9) to form the perforations 136 normal (for
example, perpendicular) to the inner face sheet 134 (FIG. 10). In
addition, the robotic forming units 208 may be configured to form
the perforations 136 at a spaced distance to the cell walls 131
(FIG. 11) of the honeycomb core 128. In this regard, the robotic
forming units 208 may be configured to form one or more
perforations 136 in each of the cells 130 at a distance from the
cell walls 131 to avoid puncturing the cell walls 131. The robotic
forming units 208 may form the perforations 136 in a perforation
pattern 140 that may be configured complementary to the geometry
and size of the cells 130 of honeycomb core 128. For example, the
perforation pattern 140 (FIG. 9) may be such that one perforation
136 (FIG. 11) is formed into each cell 130 (FIG. 11) such as at an
approximate center (not shown) of each cell 130. However, the
perforation pattern 140 may be such that two or more perforations
136 may be formed into each cell 130 of the honeycomb core 128
(FIG. 11).
[0086] The robotic forming units 208 (FIG. 9) may be configured to
index or position the perforation pattern 140 (FIG. 9) relative to
the cell 130 (FIG. 11) centers (not shown) or relative to the cell
walls 131 (FIG. 11) of a honeycomb core 128. For example, for a
honeycomb core 128 having a generally uniform arrangement of cells
130 of equal size and shape, the robotic forming units 208 may be
configured to establish a location of one of the cell walls 131 in
order to index a perforation pattern 140 relative to the locations
of the cell 130 of the honeycomb core 128. After establishing the
location of one or more cell walls 131, the robotic forming units
208 may be configured to form the perforation pattern 140 of
perforations 136 in the inner face sheet 134 of the honeycomb core
128 such that each perforation 136 is formed at a predetermined
location in each cell 130 such as at a center (not shown) of each
cell 130, or at a predetermined location or spaced distance 146
relative to the cell walls 131 of each cell 130. The perforation
pattern 140 may also be such that multiple perforations 136 may be
formed into each cell 130 and may be located at predetermined
distances or spaced distances 146 from the cell walls 131 of each
cell 130.
[0087] Advantageously, the robotic forming units 208 (FIG. 9) may
be configured to form perforations 136 (FIG. 9) within a relatively
high positional tolerance (e.g., 0.010 inch on centers) in the
hole-to-hole spacing. In addition, as indicated above, each one of
the end effectors 234 (FIG. 10) may include a vacuum attachment 240
(FIG. 10) configured to be positioned adjacent to or against the
inner face sheet 134 during the forming of the perforations 136.
The vacuum attachment 240 may include a vacuum port 242 (FIG. 11)
that may be coupled to a vacuum source (not shown) via a vacuum
hose (not shown) to provide a vacuum 244 (FIG. 10) for suctioning
dust, chips, and other debris away from a location where a
perforation 136 is being drilled.
[0088] Step 310 of the method 300 of FIG. 13 may include
periodically changing the forming bits 236 (FIG. 10) of the end
effectors 234 (FIG. 10) during the process of forming perforations
136 (FIG. 10) in the inner barrel section 120 (FIG. 10). In an
embodiment, the method may include robotically changing the forming
bits 236 using an automated bit changer (not shown). Forming bits
236 may be replaced after forming a predetermined quantity of
perforations 136. For example, each forming bit 236 may be replaced
after forming several thousand or more perforations 136. The
frequency at which the forming bits 236 may be replaced may be
affected by the thickness of the inner face sheet 134 (FIG. 11),
the material composition of the inner face sheet 134, a rotational
speed of the forming bit 236, the feed rate of the forming bit 236,
the material composition of the forming bit 236, and other factors.
In at least one embodiment, the method may include detecting when a
forming bit 236 is becoming dull, at which point the method may
include replacing the dull forming bit 236 with a new or sharpened
forming bit.
[0089] Advantageously, the forming system 200 (FIG. 12) and method
disclosed herein provides for operating a plurality of robotic
forming units 208 (FIG. 12) in a synchronized manner to accurately
and rapidly form perforations 136 (FIG. 12) in the inner face sheet
134 (FIG. 12) of an inner barrel section 120 (FIG. 12) with a high
degree of repeatability. In addition, the forming system 200
provides a means for forming perforations 136 with a significant
reduction in defects and rework commonly associated with
conventional methods. In this regard, the forming system 200 and
method disclosed herein may avoid the above-mentioned defects of
missing perforations (not shown) and/or blocked perforations (not
shown) during subsequent processing in a multi-stage barrel section
fabrication process (not shown), and the associated reduction in
percent-open-area 144 (FIG. 9) in the inner face sheet 134 of the
inner barrel section 120.
[0090] As indicated above, the percent-open-area 144 (FIG. 9) of
the inner face sheet 134 is the total area of the perforations 136
(FIG. 9) as a percentage of the surface area (not shown) of the
inner face sheet 134 (FIG. 9) and is a characteristic for measuring
the overall effectiveness or acoustic-attenuating capability of the
inner barrel section 120 (FIG. 9). In FIG. 9, the robotic forming
units 208 (FIG. 9) may be operated in a manner to form perforations
136 to provide a percent-open-area 144 (FIG. 9) in one section 148
(FIG. 9) of the inner face sheet 134 that is different than the
percent-open-area 144 in another section 150 (FIG. 9) of the face
sheet 134. For example, in FIG. 9, a first section 148 of
perforations 136 formed in the inner face sheet 134 may have a
larger percent-open-area 144 relative to a second section 150 of
perforations 136 which may be located adjacent to a forward edge
124 and/or an aft edge 126 of the barrel section 120. However, as
indicated above, differing sections (not shown) of
percent-open-area 144 may be arranged in any manner along the inner
face sheet 134 of the inner barrel section 120 (FIG. 9), and are
not limited to the arrangement shown in FIG. 9 or described
above.
[0091] FIG. 14 illustrates an interior face view of the inner face
sheet 134 having a plurality of elongated perforations 136,
according to an embodiment of the present disclosure. The inner
face sheet 134 may be formed of a cured composite material.
Alternatively, the face sheet 134 may be formed of a metallic
structure. Each perforation 136 may be formed as a non-circular
opening formed through the face sheet 134. For example, the
perforations 136 may be formed as elongated slots. In at least one
embodiment, the slots 136 may be approximately 0.1 inch long. In at
least one another embodiment, the slots 136 may be approximately
0.7 inch long. It is to be understood, however, that the slots may
be greater or lesser than 0.1 inch long or greater or lesser than
0.7 inch long.
[0092] The percent-open-area of the face sheet 134 (that is, the
area of the face sheet 134 that is occupied by the perforations
136) may be approximately 30%. Alternatively, the percent-open-area
of the face sheet 134 may be greater or lesser than 30%. For
example, in at least one embodiment, the percent-open-area may be
15%. In at least one other embodiment, the percent-open-area may be
50%. The percent-open-area may be determined by the size, shape,
weight, and other properties of the acoustic inlet barrel. For
example, if the acoustic core of the acoustic inlet barrel has
relatively large, thick honeycomb cells, the percent-open-area may
be increased beyond 30%, as the larger, thicker honeycomb cells may
more efficiently absorb sound energy. Conversely, if the acoustic
core of the acoustic inlet barrel has smaller cells, the
percent-open-area may be less than 30%.
[0093] Overall, the use of elongated perforations 136 allows for
simpler, easier, and more efficient manufacturing processes. For
example, if it is determined that additional percent-open-area is
desired, the elongated perforations 136 may be elongated to a
greater length. In contrast, if circular openings were used, an
entire hole pattern may need to be determined and recalculated, and
an initial face sheet having an undesired hole pattern may need to
be discarded.
[0094] As shown, rows 1000, 1002, 1004, 1006, 1008, and 1010 of
elongated perforations 136 may be offset with respect to one
another. For example, perforations 136 in the row 1000 may not be
radially aligned (or vertically aligned, as shown in FIG. 14) with
the perforations 136 in the row 1002. For example, a leading edge
1013a of a perforation 136 in the row 1008 may be axially offset
with respect to a rear of a leading edge 1013b of a perforation 136
in the row 1010. Further, a spacing 1012 between adjacent
perforations 136 in a row may be configured to provide a desired
percent-open-area.
[0095] Each of the perforations 136 may be the same size and shape.
Alternatively, certain perforations 136 may be sized and shaped
differently than other perforations 136.
[0096] As shown, each perforation 136 may be elongated along or
otherwise with respect to a longitudinal axis 1020, which may
generally bisect each perforation into lateral halves. The
longitudinal axis 1020 may be substantially parallel to a flow
contour line 1030, which may be uniform or non-uniform. The flow
contour line 1030 represents a direction of airflow through an
acoustic inlet barrel, for example.
[0097] FIG. 15 illustrates an interior face view of the inner face
sheet 134 having a plurality of elongated perforations 136,
according to an embodiment of the present disclosure. The inner
face sheet 134 shown in FIG. 15 is similar to the inner face sheet
134 shown in FIG. 14, except that the perforations 136 with
adjacent rows may be radially aligned with one another.
[0098] FIG. 16 illustrates an interior face view of the inner face
sheet 134 having a plurality of elongated perforations 136,
according to an embodiment of the present disclosure. The inner
face sheet 134 shown in FIG. 15 is similar to the inner face sheet
134 shown in FIG. 14, except that the perforations 136 in adjacent
rows may be offset in an opposite direction.
[0099] Referring to FIGS. 14-16, the elongated, non-circular
perforations 136 may form various other patterns than shown. The
perforation pattern 136 may be any pattern desired. In at least one
embodiment, each row of perforations may include the same number of
perforations 136. In at least one other embodiment, the number of
perforations 136 in at least one row may differ than the number of
perforations 136 in other rows.
[0100] FIG. 17 illustrates a perspective interior view of an
acoustic inlet barrel 1100, according to an embodiment of the
present disclosure. The acoustic inlet barrel 1100 includes an
inner face sheet 1102 having a plurality of elongated perforations
1104. The perforations 136 may be parallel to or otherwise aligned
with a flow contour of airflow that flows from the front 1120 of
the acoustic inlet barrel 1100 to a rear 1122 of the acoustic inlet
barrel 1100.
[0101] FIG. 18 illustrates an interior face view of a perforation
1200 formed in an inner face sheet, according to an embodiment of
the present disclosure. The perforation 1200 includes an expanded
front end 1202 connected to a reduced rear end 1204. The
perforation 1200 may form a teardrop shape.
[0102] FIG. 19 illustrates an interior face view of a perforation
1300 formed in an inner face sheet, according to an embodiment of
the present disclosure. The perforation 1300 form a teardrop
shape.
[0103] FIG. 20 illustrates an interior face view of a perforation
1400 formed in an inner face sheet, according to an embodiment of
the present disclosure. The perforation 1400 may form a diamond
shape. The perforation 1400 may have angled corners 1402. The
corners 1402 may have distinct edges, or may be blunted, rounded,
or curved.
[0104] FIG. 21 illustrates an interior face view of a perforation
1500 formed in an inner face sheet, according to an embodiment of
the present disclosure. The perforation 1500 may have a dogbone or
barbell shape.
[0105] Referring to FIGS. 22 and 23, embodiments of the disclosure
may be described in the context of an aircraft manufacturing and
service method 400 as shown in FIG. 22 and an aircraft 402 as shown
in FIG. 23. During pre-production, exemplary method 400 may include
specification and design 404 of the aircraft 402 and material
procurement 406. During production, component and subassembly
manufacturing 408 and system integration 410 of the aircraft 402
takes place. Thereafter, the aircraft 402 may go through
certification and delivery 412 in order to be placed in service
414. While in service by a customer, the aircraft 402 is scheduled
for routine maintenance and service 416 (which may also include
modification, reconfiguration, refurbishment, and so on).
[0106] Each of the processes of method 400 may be performed or
carried out by a system integrator, a third party, and/or an
operator (e.g., a customer). For the purposes of this description,
a system integrator may include without limitation any number of
aircraft manufacturers and major-system subcontractors; a third
party may include without limitation any number of venders,
subcontractors, and suppliers; and an operator may be an airline,
leasing company, military entity, service organization, and so
on.
[0107] As shown in FIG. 23, the aircraft 402 produced by exemplary
method 400 may include an airframe 418 with a plurality of systems
420 and an interior 422. Examples of high-level systems 420 include
one or more of a propulsion system 424, an electrical system 426, a
hydraulic system 428, and an environmental system 430. Any number
of other systems may be included. Although an aerospace example is
shown, the principles of the invention may be applied to other
industries, such as the automotive industry.
[0108] Apparatus and methods embodied herein may be employed during
any one or more of the stages of the production and service method
400. For example, components or subassemblies corresponding to
production process 408 may be fabricated or manufactured in a
manner similar to components or subassemblies produced while the
aircraft 402 is in service. Also, one or more apparatus
embodiments, method embodiments, or a combination thereof may be
utilized during the production stages 408 and 410, for example, by
substantially expediting assembly of or reducing the cost of an
aircraft 402. Similarly, one or more of apparatus embodiments,
method embodiments, or a combination thereof may be utilized while
the aircraft 402 is in service, for example and without limitation,
to maintenance and service 416.
[0109] As described above, embodiments of the present disclosure
provide systems and methods for forming perforations in an acoustic
structure that minimize, eliminate, or otherwise reduce the
occurrence of blocked or missing perforations, and which may be
performed in a timely and cost-effective manner. Further,
embodiments of the present disclosure provide systems and methods
for efficiently forming perforations within an acoustic structure.
Moreover, embodiments of the present disclosure provide systems and
methods of manufacturing complex geometric patterns of perforations
on an acoustic inlet barrel of an aircraft engine, or other such
structure.
[0110] As described above, embodiments of the present disclosure
provide systems and methods of forming an acoustic inlet barrel of
an engine of an aircraft. Embodiments of the present disclosure may
be used with respect to various other components other than
acoustic inlet barrels. For example, embodiments of the present
disclosure may be used with respect to various other acoustic
treatments within propulsion systems, such as translating sleeves,
inner walls, and the like. In short, embodiments of the present
disclosure are not limited to acoustic inlet barrels.
[0111] While various spatial and directional terms, such as top,
bottom, lower, mid, lateral, horizontal, vertical, front and the
like may be used to describe embodiments of the present disclosure,
it is understood that such terms are merely used with respect to
the orientations shown in the drawings. The orientations may be
inverted, rotated, or otherwise changed, such that an upper portion
is a lower portion, and vice versa, horizontal becomes vertical,
and the like.
[0112] As used herein, a structure, limitation, or element that is
"configured to" perform a task or operation is particularly
structurally formed, constructed, or adapted in a manner
corresponding to the task or operation. For purposes of clarity and
the avoidance of doubt, an object that is merely capable of being
modified to perform the task or operation is not "configured to"
perform the task or operation as used herein.
[0113] It is to be understood that the above description is
intended to be illustrative, and not restrictive. For example, the
above-described embodiments (and/or aspects thereof) may be used in
combination with each other. In addition, many modifications may be
made to adapt a particular situation or material to the teachings
of the various embodiments of the disclosure without departing from
their scope. While the dimensions and types of materials described
herein are intended to define the parameters of the various
embodiments of the disclosure, the embodiments are by no means
limiting and are exemplary embodiments. Many other embodiments will
be apparent to those of skill in the art upon reviewing the above
description. The scope of the various embodiments of the disclosure
should, therefore, be determined with reference to the appended
claims, along with the full scope of equivalents to which such
claims are entitled. In the appended claims, the terms "including"
and "in which" are used as the plain-English equivalents of the
respective terms "comprising" and "wherein." Moreover, the terms
"first," "second," and "third," etc. are used merely as labels, and
are not intended to impose numerical requirements on their objects.
Further, the limitations of the following claims are not written in
means-plus-function format and are not intended to be interpreted
based on 35 U.S.C. .sctn.112(f), unless and until such claim
limitations expressly use the phrase "means for" followed by a
statement of function void of further structure.
[0114] This written description uses examples to disclose the
various embodiments of the disclosure, including the best mode, and
also to enable any person skilled in the art to practice the
various embodiments of the disclosure, including making and using
any devices or systems and performing any incorporated methods. The
patentable scope of the various embodiments of the disclosure is
defined by the claims, and may include other examples that occur to
those skilled in the art. Such other examples are intended to be
within the scope of the claims if the examples have structural
elements that do not differ from the literal language of the
claims, or if the examples include equivalent structural elements
with insubstantial differences from the literal language of the
claims.
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