U.S. patent application number 15/937165 was filed with the patent office on 2018-08-09 for spar for a blade, and a blade.
This patent application is currently assigned to AIRBUS HELICOPTERS. The applicant listed for this patent is AIRBUS HELICOPTERS. Invention is credited to Andre AMARI, Jacques GAFFIERO, Benedicte RINALDI.
Application Number | 20180222129 15/937165 |
Document ID | / |
Family ID | 52130289 |
Filed Date | 2018-08-09 |
United States Patent
Application |
20180222129 |
Kind Code |
A1 |
GAFFIERO; Jacques ; et
al. |
August 9, 2018 |
SPAR FOR A BLADE, AND A BLADE
Abstract
A method of fabricating a spar for a blade, which spar includes
transversely at least one arrangement. A male former is defined for
each arrangement that is to be fabricated and each arrangement is
subdivided into a pressure-side subassembly and a suction-side
subassembly, each comprising a plurality of hanks, each hank
comprising a plurality of U-shaped tape segments stacked on one
another. Each subassembly of an arrangement is fabricated outside a
mold for fabricating the blade on a single former adapted to that
particular arrangement, fabrication being by stacking tape segments
on the former using a fiber placement method implemented by a
placement head.
Inventors: |
GAFFIERO; Jacques; (PARIS,
FR) ; RINALDI; Benedicte; (PARIS, FR) ; AMARI;
Andre; (LA CHAPELLE EN SERVAL, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AIRBUS HELICOPTERS |
Marignane |
|
FR |
|
|
Assignee: |
AIRBUS HELICOPTERS
Marignane
FR
|
Family ID: |
52130289 |
Appl. No.: |
15/937165 |
Filed: |
March 27, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14800965 |
Jul 16, 2015 |
9950478 |
|
|
15937165 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 70/386 20130101;
B33Y 80/00 20141201; B64C 27/473 20130101; B29K 2105/0872 20130101;
B29L 2031/082 20130101; B29D 99/0025 20130101; B64C 2027/4736
20130101; B29C 70/382 20130101; F01D 5/147 20130101 |
International
Class: |
B29C 70/38 20060101
B29C070/38; B29D 99/00 20100101 B29D099/00; B64C 27/473 20060101
B64C027/473; B33Y 80/00 20150101 B33Y080/00; F01D 5/14 20060101
F01D005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2014 |
FR |
14 01624 |
Claims
1. A blade having at least one fastener bushing and a spar, the
spar including an arrangement wound around the fastener bushing,
the arrangement comprising a pressure-side subassembly and a
suction-side subassembly, the arrangement extending spanwise and
comprising in succession a root zone in the region of the fastener
bushing, a connection zone, and then a running zone, wherein at
least one section referred to as "connection" section of the
arrangement in the connection zone is lozenge-shaped, the
pressure-side subassembly being V-shaped and the suction-side
subassembly having an upside-down V-shape in the connection
section.
2. The blade according to claim 1, wherein each section referred to
as "root" section of the arrangement in the root zone comprises at
least one rectangular slab extending in elevation along its length,
the root axis being a vertical axis substantially orthogonal to the
plane in which the spar extends spanwise.
3. The blade according to claim 1, wherein at least one section of
a leading-edge arrangement presents a C-shape in the running zone,
with a trailing-edge arrangement extending the C-shape in a suction
side and in a pressure side of the blade.
4. The blade according to claim 1, wherein the root zone is
provided with a C-shaped root wall forming an end wall; the
connection zone having two twisted connection walls connected
respectively to two ends of the end wall; and the running zone
having two running walls connected respectively to the two
connection walls.
5. The blade according to claim 4, wherein the arrangement
comprises a plurality of U-shaped tape segments stacked on one
another.
6. The blade according to claim 5, wherein the tape segments are
disposed around a root axis.
7. The blade according to claim 6, wherein the arrangement includes
a void forming an inside volume of the spar.
8. The blade according to claim 6, wherein the arrangement includes
a fastener bushing, a root wedge surrounding the fastener bushing,
and a filler material.
9. The blade according to claim 5, wherein at least one of tape
segments covers, in the running zone, another of the tape segments
over a chord width that decreases.
10. The blade according to claim 5, wherein at least one of the
tape segments extends spanwise from the root axis over a first
length, and at least one other of the tape segment extends spanwise
from the root axis over a second length that is different from the
first length so as to impart decreasing thickness to the
arrangement.
11. A blade having at least one fastener bushing and a spar
including an arrangement disposed about the fastener bushing, the
arrangement comprising a pressure-side subassembly and a
suction-side subassembly, the arrangement extending spanwise and
comprising in succession a root zone in the region of the fastener
bushing, a connection zone, and then a running zone, wherein at
least one section referred to as "connection" section of the
arrangement in the connection zone is lozenge-shaped, with the
pressure-side subassembly being substantially V-shaped and the
suction-side subassembly having a substantially upside-down V-shape
in the connection section.
12. The blade according to claim 11, wherein each section referred
to as "root" section of the arrangement in the root zone comprises
at least one substantially rectangular slab extending in elevation
along its length, the root axis being a vertical axis substantially
orthogonal to the plane in which the spar extends spanwise.
13. The blade according to claim 11, wherein at least one section
of a leading-edge arrangement presents a substantially C-shape in
the running zone, with a trailing-edge arrangement extending the
C-shape in a suction side and in a pressure side of the blade.
14. The blade according to claim 11, wherein the root zone includes
a substantially C-shaped root wall forming an end wall; the
connection zone having two twisted connection walls connected
respectively to two ends of the end wall; and the running zone
having two running walls connected respectively to the two
connection walls.
15. The blade according to claim 14, wherein the arrangement
comprises a plurality of tape segments stacked on one another.
16. The blade according to claim 15, wherein the tape segments are
substantially U-shaped and are disposed about a root axis.
17. The blade according to claim 16, wherein the arrangement
includes a void forming an inside volume of the spar.
18. The blade according to claim 16, wherein the arrangement
includes a fastener bushing, a root wedge surrounding the fastener
bushing, and a filler material.
19. The blade according to claim 15, wherein at least one of tape
segments covers, in the running zone, another of the tape segments
over a chord width that decreases.
20. The blade according to claim 15, wherein at least one of the
tape segments extends spanwise from the root axis over a first
length, and at least one other of the tape segment extends spanwise
from the root axis over a second length that is different from the
first length so as to impart decreasing thickness to the
arrangement.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 14/800,965 filed Jul. 16, 2015, which claims priority to French
patent application No. FR 14 01624 filed on Jul. 18, 2014, the
disclosures of which are incorporated in their entirety by
reference herein.
BACKGROUND OF THE INVENTION
(1) Field of the Invention
[0002] The present invention relates to a fabricated spar for a
blade, and to a fabricated blade.
(2) Description of Related Art
[0003] A rotorcraft has at least one engine that drives a main
rotor in rotation in order to provide the rotorcraft with lift and
possibly also propulsion. The main rotor has a hub carrying a
plurality of blades.
[0004] Blades conventionally comprise at least one spar extending
spanwise from the root of the blade.
[0005] While they are rotating, the blades are subjected to a force
torsor. The blades are subjected to centrifugal force and also to
multiple forces and bending and twisting moments due to the
movements of the blade, in particular due to its flapping movements
and its lead-lag movements.
[0006] Consequently, a particular function of the spar is to
transmit the forces to which the blade is subjected to the hub, and
in particular to transmit centrifugal force.
[0007] A first type of blade has a spar arranged at the leading
edge of the blade. The spar extends from the root of the blade
along the span of the blade. That type of spar is referred to below
for convenience as a "leading-edge" spar.
[0008] Such a leading-edge spar also contributes to static chord
balancing of the blade.
[0009] Furthermore, the leading-edge spar tends to improve ability
to withstand damage caused as a result of an object impacting
against the leading edge.
[0010] A second type of blade has a spar referred to as a
"distributed" spar. Such a distributed spar consists in a
leading-edge spar that is extended in its running portion by two
portions that are arranged flat respectively on the pressure side
and on the suction side of the blade. In its running portion, a
distributed spar thus has cross-sections of C-shape in a transverse
plane that is substantially parallel to the axis of rotation of the
rotor.
[0011] The distributed spar thus has a solid leading edge. This
leading edge is extended by a top flap extending over the suction
side of the blade and a bottom flap extending over the pressure
side of the blade.
[0012] In addition to having the advantages of a leading-edge spar,
a distributed spar tends to make the blade stiffer in flapping.
[0013] Furthermore, a distributed spar tends to optimize the
strength of the blade by imparting advantageous strength to the
blade in the event of local damage.
[0014] Nevertheless, it is difficult to fasten a blade having a
distributed spar to a rotor hub.
[0015] In order to be fastened to a hub, the distributed spar of a
blade may for example be wound at its root end around at least one
vertical axis that is substantially parallel to the axis of
rotation of the rotor. The blade is then fastened to the rotor by
inserting a pin extending along such a vertical axis.
[0016] Nevertheless, fabricating such a distributed spar that is
wound around at least one vertical pin can be difficult.
[0017] In a first step, an operator fabricates tape by impregnating
resin into glass fiber roving arranged side by side and calendared
to have the dimensions of the desired tape. The tape is assembled
with a separator film and then wound on a reel or "roll".
[0018] Prior to being polymerized, the roving tape used for
fabricating blades presents very good capacity for deformation.
This deformation capacity enables an operator to obtain complex
variations in shape by smoothing manually.
[0019] In a second step, the operator builds individual hanks from
segments of a roving tape. Each hank then presents a plurality of
layers of roving type.
[0020] Each individual hank is in the form of a long loop closely
wound around a root wedge, the hank having sections that are
substantially rectangular. Each hank has a C-shape in a plane that
is substantially orthogonal to the axis of rotation of the rotor.
Thus, each hank has two lateral strands connected to an end wall
juxtaposed against the root wedge. Such a root wedge is an elongate
part made of composite materials that is for receiving a fastener
bushing.
[0021] In a third step, the operator drapes a skin over a first
half-shell of a mold in order to embody the pressure side of the
blade, and over a second half-shell of the mold in order to embody
the suction side of the blade.
[0022] The hanks are then placed in the half-shells in order to be
smoothed. The hank portion that is wound about the fastener bushing
of the hanks are left practically untouched by the operator. In
contrast, the two hanks of each strand are handled by the operator
so as to be arranged in pre-established positions along the span of
the blade.
[0023] Finally, the hanks are worked manually during a smoothing
operation in order to cause the material to deform and to present
predefined variations in section.
[0024] At identified reference positions along the blades,
operators make use of templates that embody the sections to be
given to the spar so as to ensure that the strands of the hanks are
deformed progressively and as regularly as possible.
[0025] Performing the third step is found to be difficult.
[0026] The shapes of the spar are relatively simple at the fastener
bushing and in the running portion of the blade. In simplified
manner, the hanks extend substantially vertically in the vicinity
of the fastener bushing and substantially horizontally at the
pressure side and the suction side. In contrast, the path followed
by each hank between those two end zones is complex. This path in
particular is twisted in a complex zone referred to as the
"connection" zone.
[0027] Furthermore, it is not easy to lay the hank fibers coming
from the twisted section of the distributed spar so that they are
flat on the suction side and the pressure side of the blade.
[0028] The twisting in the connection zone can then lead to shapes
being poorly reproducible, and also to the mechanical and vibratory
characteristics being poorly reproducible from one blade to
another.
[0029] Furthermore, if filler elements need to be arranged in the
blade, then the filler elements need to be complex in shape and to
vary from one blade to another when the twisting of the spar is not
reproduced identically. Blade fabrication can then be difficult to
automate.
[0030] Document FR 2 918 347 proposes a fastener bushing enabling
the distributed spar to be wound not around a vertical axis but
rather around a horizontal axis.
[0031] Document JP S63-179706 describes a blade having two fastener
bushings. The blade has a spar provided with a box including a
rounded tip. The box is then extended by two arms each of which is
wound around a fastener bushing.
[0032] Documents FR 2 321 997, FR 2 030 036, EP 1 035 963, and FR
993 491 are remote from the problems of the invention.
[0033] Documents DE 2 738 514 and GB 2 092 543 are also known.
[0034] Document FR 2 321 997 discloses a method of fabricating
articles of non-circular section by winding continuous
filaments.
[0035] That method makes use of a stationary mandrel that is
inflatable. The mandrel is inflated in order to become circular in
shape and is then set into rotation. Continuous filaments are then
wound around the mandrel and coated in a curable resin.
[0036] The mandrel is then deflated to transform the winding into a
deformable sheath.
[0037] The deformable sheath is then placed in the cavity of a
mold. Thereafter an operator raises the pressure inside the sheath
in order to cause the winding to fit closely to the shape of the
mold. Finally, the operator causes the resin to cure in order to
transform the sheath into a rigid hollow structure.
[0038] That method of winding continuous fibers around a stationary
mandrel does not appear to be suitable for a distributed spar for a
blade.
[0039] According to Document FR 2 030 036, an operator performs
winding to make a cylindrical element that is to constitute the
outer skin of the blade. The cylindrical element is then subdivided
into two subassemblies, each of which is placed in a mold.
[0040] The spar of the blade is also made by winding.
[0041] The spar has a first block of fiber layers presenting an
angle of 45.degree. with the longitudinal axis of the blade, and
then a second block of fiber layers presenting an angle of
30.degree. with the longitudinal axis, and finally a third block of
fiber layers presenting an angle of 15.degree. with the
longitudinal axis.
[0042] The spar projects to the outside at the blade root through
an opening, and a wound attachment is wedged in the opening.
Thereafter, the spar is inserted between the two molds in which the
two subassemblies of the outer skin of the blade are arranged.
[0043] That fabrication method is effective but appears to be
difficult to adapt to a distributed spar. Furthermore, multiple
steps need to be performed.
[0044] Document EP 1 035 963 describes a control system for a
fiber-placement device. That document EP 1 035 963 nevertheless
does not give any teaching about a spar for a blade.
[0045] The fiber-placement method is an alternative to winding a
continuous filament.
[0046] Fiber placement is a method of laying fibers, tapes, roving,
or other similar reinforcement, while dry or when pre-impregnated
with resin, on surfaces of various shapes. The placement is
performed by using a device having a movable placement head. The
placement head thus ensures that the material used is positioned on
a surface by making direct mechanical contact with the surface. For
this purpose, the placement head is moved by a movement system of
the type comprising a robot or a positioning gantry, with degrees
of freedom in movement that are servo-controlled depending on the
shape of the surface to be covered.
[0047] The fiber-placement method thus makes it possible in
particular to make surfaces of large dimensions and small
thicknesses, within the limits set by the size of the placement
head.
[0048] In particular, the fiber-placement method makes it possible
automatically to perform operations of laying discontinuous fibers
by performing starting, laying, and cutting operations.
[0049] Document FR 2 993 491 discloses a fiber-placement
machine.
[0050] It should be observed that placing a roving tape by means of
a placement system can be difficult. The material in the form of
tapes as laid by placement systems tends to be viscous. That method
then provides little latitude to an operator for smoothing the
tape, and that can appear to be incompatible with making a
spar.
[0051] Furthermore, the size of the volumes swept by a placement
head would not appear to be compatible with the volumes of the
half-shells used when fabricating a blade using the above-described
method.
[0052] Finally, a spar presents large thicknesses, unlike the parts
that are generally fabricated by fiber placement.
[0053] In addition, a spar presents sections in its span direction
that are of a very great variety of kinds. Under such
circumstances, fabricating a spar by applying a fiber-placement
method would appear to be difficult to perform.
BRIEF SUMMARY OF THE INVENTION
[0054] An object of the invention is thus to provide a method of
fabricating a spar for a blade by fabricating a distributed spar of
a blade with the help of a composite material.
[0055] The invention thus provides a method of fabricating a spar
of a blade using tapes of composite materials, said spar having at
least one arrangement, each arrangement being for winding around a
root axis, the method comprising the following steps:
[0056] during a preparation step, defining one male former per
arrangement to be fabricated, each former having a pressure-side
running surface, and a suction-side running surface of U-shape,
each running surface comprising:
[0057] a root zone provided with a C-shaped root wall forming an
end wall of said U-shape;
[0058] a connection zone presenting two twisted connection walls
that are connected respectively to two ends of said end wall;
and
[0059] a running zone presenting two running walls connected
respectively to the two connection walls;
[0060] during a fabrication step, subdividing each arrangement into
a pressure-side subassembly and a suction-side subassembly, each
comprising at least one hank, each hank comprising a plurality of
U-shaped tape segments stacked on one another;
[0061] during said fabrication step, fabricating said pressure-side
subassembly and said suction-side subassembly of an arrangement on
a single former adapted to the arrangement and outside a mold for
fabricating said blade, said pressure-side subassembly and said
suction-side subassembly of an arrangement being fabricated by
stacking tape segments on said former by a fiber placement method
using a placement head, said placement head winding each tape
segment of the pressure-side subassembly around a root axis by
laying said segment over the pressure-side running surface, said
placement head winding each tape segment of the suction-side
subassembly around a root axis by laying said segment on the
suction-side running surface; and
[0062] during a heating step, heating each arrangement on its
former.
[0063] Thus, if the tape segments include a thermosetting resin,
then the spar is polymerized on being heated. If the tape segments
include a thermoplastic resin, then the spar is consolidated on
being heated.
[0064] The method thus proposes defining a former for each type of
arrangement.
[0065] The former defines a pressure-side running surface and a
suction-side running surface. Each arrangement is thus subdivided
into a pressure-side subassembly for laying on a pressure-side
running surface and a suction-side subassembly for laying on a
suction-side surface.
[0066] Under such circumstances, the method proposes making a spar
by laying U-shaped tape segments on a former so as to fabricate the
various hanks. Such a tape may be a low-track tape provided with
fibers that have been impregnated by the "solvent" technique.
[0067] The method thus defines the paths to be followed by a fiber
placement head in order to obtain a spar presenting various
sections. In particular, the method makes it possible to make a
spar having a root axis referred to as "vertical" axis that is
substantially orthogonal to the plane in which said spar extends
spanwise. Such a root axis is then substantially parallel to the
axis of rotation of the rotor fitted with the blade having the
spar.
[0068] Under such circumstances, it becomes possible to lay tape
segments by using a placement head mounted on the arm of a
robot.
[0069] The arm may be moved in translation along a longitudinal
bench extending parallel to a former. Furthermore, the head can
also be tilted relative to the arm so as to be able to go around
the root zone. The placement head thus presents six degrees of
freedom, thereby enabling each tape segment to be laid along a
U-shaped path.
[0070] The tape segments are thus laid in full and automatically on
a former outside the mold for a blade, unlike certain present-day
manual methods.
[0071] Consequently, the spars obtained by the method can be
substantially identical to one another.
[0072] This method also presents the advantage of making it
possible to fabricate a spar that is solid along its leading edge,
i.e. a spar presenting considerable thickness. Nevertheless, the
fiber placement method used to appear to be unsuitable for such
fabrication.
[0073] As explained below, the former makes it possible to obtain
hanks that are suitable for obtaining a solid leading edge.
[0074] Furthermore, the method makes it possible in particular to
fabricate a distributed spar that is hollow in its running
portion.
[0075] In addition, the method also makes it possible to make a
spar that is wound around two optionally vertical pins, which used
to appear to be incompatible with a path that can be followed by a
placement head.
[0076] The method makes it possible to make a first arrangement on
a first former and a second arrangement on a second former. The
formers are then placed adjacent to each other prior to the step of
heating the arrangements.
[0077] The tape segments are then laid in two passes, respectively
on two different formers.
[0078] The method may also include one or more of the following
characteristics.
[0079] Thus, the connection walls of a former together form a
lozenge-shape (< >) as seen in chord section of the former,
thereby facilitating the laying of said segments.
[0080] This shape enables a placement head to lay the tape segments
without risk of interfering with an auxiliary structure.
[0081] Furthermore, during said fabrication step, said placement
head winds each tape segment of the pressure-side subassembly
around a root axis by laying said segment over a first running wall
of the pressure-side running surface, a first connection wall of
the pressure-side running surface, the root wall, a second
connection wall of the pressure-side running surface, and a second
running wall of the pressure-side running surface, said placement
head winding each tape segment of the suction-side subassembly
around a first root axis by laying said segment over a first
running wall of the suction-side running surface, a first
connection wall of the suction-side running surface, the root wall,
a second connection wall of the suction-side running surface, and a
second running wall of the suction-side running surface.
[0082] The paths to be followed can thus be followed by a fiber
placement head.
[0083] In addition, these paths make it possible in particular to
obtain hanks that are provided with sections that are rectangular
in the root zone. The hanks are then twisted in the connection zone
and then spread out in the running zone.
[0084] The hank sections can be made to vary in spite of the
material from which certain types of composite tape are made
presenting very little ability to deform in creep.
[0085] The spreading is performed by a pre-programmed distribution
of the directions in which the tapes are applied in the running
zone. For example, the tape segments are offset transversely in the
chord direction in alternation to the "left" and to the "right"
relative to a middle direction, thereby making it possible to
obtain the desired variations in section.
[0086] Furthermore, at least one former may be a removable former
that is formed by using tooling representing an inside volume of a
spar, said former being removed after said heating step.
[0087] The tape segments are then laid on a male former
representative of the inside volumes that are surrounded by the
spar.
[0088] Alternatively, at least one former is a non-removable former
that is formed by a fastener bushing, a root wedge surrounding said
fastener bushing, and a filler material of a blade.
[0089] The inside volume on which the tape segments are laid is
then constituted by real individual parts that are to form portions
of the blade. These individual parts may include, for example, a
complete fastener bushing, a root wedge extending the bushing, and
"lightweight" filler material that extends spanwise from the root
wedge. Such a filler material may be a polyurethane type foam, for
example.
[0090] Furthermore, the former may be arranged on tooling that is
secured to a rocker, said rocker rocking the former during the
fabrication step.
[0091] For example, the former may be fastened on a rocker by means
of tooling. The tooling enables the former to be turned about its
longitudinal axis of symmetry so as to be able to cover either its
pressure-side running surface or else its suction-side running
surface.
[0092] In addition, the rocker can rock during the operation of
laying tape segments so as to facilitate movements of the placement
head, in particular while turning around the root zone.
[0093] Advantageously, and in the context of a "vertical" type root
axis, the rocking axis of the rocker passes through the vertical
axis of the root zone and remains parallel with the longitudinal
axis of symmetry of the former.
[0094] In another aspect, during the fabrication step, said hanks
are formed one after another by laying all of the segments of one
of the hanks on a former before laying the segments of another
hank.
[0095] Furthermore, the sections of the hanks can be thought of as
rectangles in the root zone. These sections can be made to vary so
as to become tapering surfaces in order to match the stresses
applied along the span.
[0096] In a first alternative, tapering may be performed by
reducing the width of the tapes, as is made possible by subdividing
the tape.
[0097] Thus, at least one tape segment of a subassembly covers, in
the running zone, another segment of the subassembly over a chord
width that decreases going away from said root axis.
[0098] In a second alternative, tapering may be performed in the
span direction of the blade by cutting tape sections along a
radius.
[0099] Thus, at least one tape segment of a subassembly extends
spanwise from said root axis over a length referred to as a "first"
length, and at least one other segment extends spanwise from said
root axis over a length referred to as a "second" length that is
different from the first length so as to impart decreasing
thickness to the subassembly.
[0100] The first and second alternatives may be combined.
[0101] Furthermore, said spar includes an arrangement referred to
as a "trailing-edge" arrangement, and a "trailing-edge" former is
defined that is provided with a pressure-side running surface and
with a suction-side running surface that are vertically spaced
apart from each other.
[0102] In addition, said spar may have a "leading-edge"
arrangement, and a "leading-edge" former is defined having a
pressure-side running surface and a suction-side running surface
that join together to form a tip.
[0103] After the tape segments have been laid, the leading-edge
former and the trailing-edge former can be fastened together prior
to heating said segments.
[0104] After the heating step, a single-piece spar is obtained
provided with the leading-edge arrangement and with the
trailing-edge arrangement.
[0105] Furthermore, the leading-edge former may, for example,
present:
[0106] a suction-side running surface provided transversely with an
outer suction-side zone and an inner suction-side zone that are
spaced apart vertically by a suction-side step; and
[0107] a pressure-side running surface that is provided
transversely with an outer pressure-side zone and with an inner
pressure-side zone that are spaced apart vertically by a
pressure-side step, the inner pressure-side zone and the inner
suction-side zone joining together to form said tip.
[0108] Such a leading-edge former makes it possible to obtain a
spar that is solid at the leading edge of a blade. The leading-edge
former enables hanks to be stacked so as to give the spar
considerable thickness.
[0109] Thereafter, the laying of segments of a hank of the
pressure-side subassembly may be alternated with the laying of
segments of a hank of the suction-side subassembly, with a strand
of one hank being placed adjacent against a strand of the
previously-laid hank in the region of said tip in order to form a
herring-bone configuration at the leading-edge.
[0110] The term "strand" is used to designate a segment of a
hank.
[0111] More particularly, during the fabrication step, the
following steps are performed:
[0112] forming a first hank of the suction-side subassembly by
organizing a plurality of segments on said former using said
placement head, each segment of the first hank comprising in
succession a first strand with a central strand and a second
strand, the first strand being laid on the outer suction-side zone
and a suction-side connection zone, the central strand being laid
on a suction-side root zone, and the second strand being laid on
the suction-side connection zone and the inner suction-side zone, a
suction-side portion of the outer suction-side zone leading to the
suction-side step not being covered by the first strand, the second
strand projecting transversely from the inner suction-side
zone;
[0113] forming a second hank of the pressure-side subassembly by
organizing a plurality of segments on said former using said
placement head, each segment of the second hank comprising in
succession a third strand with a central strand and a fourth
strand, the third strand being laid on the outer pressure-side zone
and on a pressure-side connection zone, the central strand being
laid on a pressure-side root zone, the fourth strand being laid on
the pressure-side connection zone and on the inner pressure-side
zone, a pressure-side portion of the outer pressure-side zone
leading to a pressure-side step not being covered by the first
strand, the fourth strand projecting transversely from the inner
pressure-side in order to press against an edge of the first
strand;
[0114] forming a third hank of the suction-side subassembly by
organizing a plurality of segments on said former using said
placement head, each segment of the third hank comprising in
succession a fifth strand with a central strand and a sixth strand,
the fifth strand being laid jointly on said suction-side portion
and partially on the second strand in the running portion and then
covering the suction-side connection zone in the running portion,
the central strand being laid on the suction-side root zone, and
the sixth strand being laid on the suction-side connection zone and
then in the running zone on the second strand and on an edge of the
fourth strand, the sixth strand projecting transversely from the
fourth strand; and
[0115] forming a fourth hank of the pressure-side subassembly by
organizing a plurality of segments on said former using said
placement head, each segment of the fourth hank comprising in
succession a seventh strand with a central strand and an eighth
strand, the seventh strand being laid jointly on said pressure-side
portion and in part on the fourth strand in the running portion and
then covering the pressure-side connection zone in the running
portion, the central strand being laid on the pressure-side root
zone, and the eighth strand being laid on the pressure-side
connection zone and then in the running zone on the fourth strand
and against an edge of the sixth strand.
[0116] The method of the invention thus makes it possible to
arrange hanks in a superposed herring-bone configuration at the
leading-edge so as to enable this portion of the spar to be made
"heavier" at will.
[0117] A small amount of manual shaping and smoothing may be
envisaged prior to heating in order to improve the shape of the
spar, locally flattening the rectangular sections of the strands so
as to give them the desired final shape.
[0118] Optionally, the portion of the first hank that is laid on
said inner suction-side zone is flush with the outer suction-side
zone, and the portion of the second hank that is laid on said inner
pressure-side zone is flush with the outer pressure-side zone.
[0119] Furthermore, the invention provides a method of fabricating
a blade, the method comprising the following steps:
[0120] fabricating a spar by applying the method as described
above;
[0121] fabricating a mold for the spar;
[0122] placing said spar in said mold; and
[0123] placing said mold in heater means for heating said
blade.
[0124] The invention also provides a blade having at least one
fastener bushing and a spar, the spar including an arrangement
wound around the fastener bushing, the arrangement comprising a
pressure-side subassembly and a suction-side subassembly, the
arrangement extending spanwise and comprising in succession a root
zone in the region of the fastener bushing, a connection zone, and
then a running zone.
[0125] At least one section referred to as "connection" section of
said arrangement in the connection zone is lozenge-shaped (<
>), said pressure-side subassembly being V-shaped and said
suction-side subassembly having an upside-down V-shape in said
connection section.
[0126] The term "upside-down" should be considered relative to an
observer looking at the spar in the span direction, the
suction-side subassembly being situated above the pressure-side
subassembly.
[0127] This feature makes it possible to make the blade while using
the above-described fiber-placement method.
[0128] The blade may then have a leading-edge arrangement and a
trailing-edge arrangement. Each arrangement may possess a
connection section that is lozenge-shaped. Nevertheless, it is
possible for only one arrangement to have such a shape.
[0129] Furthermore, when said root axis is a vertical axis
substantially orthogonal to a plane in which the spar extends
spanwise, each section referred to as "root" section of said
arrangement in the root zone may comprise at least one slab
extending lengthwise in elevation.
[0130] Conversely, each "running" section of said arrangement in
the running zone comprises at least one slab extending transversely
lengthwise.
[0131] Each slab extends lengthwise and widthwise. The "length" of
a slab of a spar thus represents the largest dimension of the
slab.
[0132] In addition, at least one section of a leading-edge
arrangement may present a C-shape in the running zone, with a
trailing-edge arrangement extending the C-shape in the suction side
and in the pressure side of the blade.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0133] The invention and its advantages appear in greater detail
from the context of the following description of embodiments given
by way of illustration and with reference to the accompanying
figures, in which:
[0134] FIG. 1 is a plan view and section view showing a blade
having a vertical root axis obtained by applying the method of the
invention;
[0135] FIG. 2 is a diagrammatic view of a fiber placement system of
the invention;
[0136] FIG. 3 is a view of a trailing-edge former carried by
tooling;
[0137] FIG. 4 is a view of a leading-edge former;
[0138] FIG. 5 is a section view of a leading-edge arrangement;
[0139] FIG. 6 is a view of a leading-edge arrangement;
[0140] FIG. 7 is a diagrammatic view of a non-removable former;
[0141] FIG. 8 is a view showing a tape segment of decreasing
width;
[0142] FIG. 9 is a view of two tape segments having different
lengths;
[0143] FIG. 10 is a view showing tape segments that are offset in
the chord direction;
[0144] FIG. 11 is a view showing how a blade is fabricated; and
[0145] FIG. 12 is a plan view and section view of a blade having a
horizontal root axis obtained by applying the method of the
invention.
[0146] Elements present in more than one of the figures are given
the same references in each of them.
DETAILED DESCRIPTION OF THE INVENTION
[0147] It should be observed that three mutually orthogonal
directions X, Y, and Z are shown in some of the figures.
[0148] The first direction X is said to be longitudinal. The term
"longitudinal" relates to any direction parallel to the first
direction X.
[0149] The second direction Y is said to be transverse. The term
"transverse" relates to any direction parallel to the second
direction Y. The chord of the fabricated blade extends
transversely, whereas the span of the blade extends
longitudinally.
[0150] Finally, the third direction Z is said to be in elevation.
The term "in elevation" relates to any direction parallel to the
third direction Z.
[0151] FIG. 1 shows a blade 1 fabricated by applying the method of
the invention.
[0152] The blade 1 has an outer skin 2 within which there extends a
spar 5.
[0153] The spar 5 thus extends longitudinally along the span of the
blade 1 in a plane P1 that extends spanwise and transversely along
the chord of the blade 1.
[0154] Each section of the blade 1 is then a cross-section parallel
to the second direction Y and to the third direction Z.
[0155] The spar 5 surrounds at least one fastener bushing. Thus,
the spar 5 has one arrangement per fastener bushing. Each
arrangement is then wound around a root axis AX1, AX2 of symmetry
of a fastener bushing. In the embodiment of FIG. 1, such a root
axis is a vertical axis substantially orthogonal to the plane P1
extending spanwise.
[0156] Nevertheless, and with reference to FIG. 12, the root axis
could be a substantially horizontal axis lying in the plane P1
extending spanwise.
[0157] With reference to FIG. 1, the blade may have two fastener
bushings 41. Under such circumstances, the spar 5 has one
arrangement referred to as the "leading-edge" arrangement 10 that
surrounds the fastener bushing closer to the leading edge of the
blade and that is wound around a first root axis AX1. In addition,
the spar 5 has another arrangement referred to as the
"trailing-edge" arrangement 15 that surrounds the fastener bushing
closer to the trailing edge of the blade, being wound around a
second root axis AX2.
[0158] FIG. 1 also shows sections of the blade in a root zone Z1, a
connection zone Z2, and a running zone Z3.
[0159] Each section of an arrangement is substantially in the form
of two rectangles in the root zone Z1. The length of each rectangle
extends substantially parallel to the corresponding root axis.
[0160] In contrast, each section of an arrangement is substantially
lozenge-shaped (< >) in the connection zone Z2, this lozenge
shape flattening on going away from the root zone.
[0161] Finally, each section of the leading-edge arrangement 10
tends to present a C-shape in the running zone Z3, the
trailing-edge arrangement 15 extending this C-shape both in the
suction side and in the pressure side of the blade in the
embodiment of FIG. 1.
[0162] Such a spar 5 and such a blade 1 can be fabricated in
automatic manner by applying the method of the invention.
[0163] The method seeks to fabricate the spar from at least one
tape of composite materials by using a fiber placement head.
[0164] With reference to FIG. 2, the method uses a system having a
robot 51. The robot 51 has an articulated arm 52 mounted on a
carriage 54 that is slidable along rails 55. In addition, the robot
51 has a placement head 53 enabling segments of a tape made of
composite materials to be laid on a support. Such a segment is
referred to as a "tape segment" for convenience.
[0165] The placement head then has six degrees of freedom, namely
three degrees of freedom to move in translation and three degrees
of freedom to move in rotation.
[0166] Furthermore, the system may include one former 20, 30 per
arrangement.
[0167] In order to fabricate a spar as shown in FIG. 1, the system
then has a leading-edge former 20 for laying tape segments in order
to embody the leading-edge arrangement 10. Furthermore, the system
also has a trailing-edge former 30 serving to lay tape segments in
order to embody the trailing-edge arrangement 15.
[0168] In order to lay tape segments made of composite materials on
a former, the former may be organized on tooling 56. Such tooling
may comprise pivot means 57 for causing the former to turn about
its longitudinal axis of symmetry AX3. The longitudinal axis AX3
may cross the axis of the former embodying the root axis AX1 about
which the arrangement in question is wound.
[0169] For example, the tooling comprises a plane plate 56' secured
to two rods 56'' suitable for carrying the former.
[0170] Furthermore, the tooling 56 may be carried by a rocker 60.
The rocker 60 may comprise a shaft 58 secured to the tooling 56,
and a servo-controlled motor 59 suitable for turning the shaft
about an axis of rotation AX3. This axis of rotation AX4 is
advantageously parallel to the longitudinal axis AX3 of the former
being carried.
[0171] The rocker then serves to tilt the former relative to the
placement head so as to facilitate laying tape segments.
[0172] The motor 59 and the robot 51 are controlled by a processor
unit. The processor unit has a processor and memory, the processor
executing instructions stored in the form of lines of code in the
memory in order to apply the method of the invention. For example,
the processor unit is a computer.
[0173] FIG. 3 shows a trailing-edge former 30 fastened to tooling
56. This FIG. 3 shows in particular tooling provided with a rod
56'' carrying pivot means 57 and a rod 56''' carrying a pin 300 for
fastening the arrangement that is to be made.
[0174] FIG. 4 shows a leading-edge former 20.
[0175] Thus, the blade fabrication method of the invention includes
a method of fabricating a spar made of composite materials. The
spar is provided with at least one fastener bushing. Under such
circumstances, the spar has one subassembly known as an
"arrangement" per fastener bushing.
[0176] In this method of fabricating a spar, one former 20, 30 is
defined per arrangement that is to be fabricated during a
preparation step STP1.
[0177] With reference to FIGS. 3 and 4, at least one former may be
a removable former made with the help of tooling and representing
an inside volume of a spar. Such a removable former is separated
from an arrangement when the arrangement is heated.
[0178] Nevertheless, and with reference to FIG. 7, at least one
former may be a non-removable former. The non-removable former then
includes a fastener bushing 41, a root wedge 42 surrounding the
fastener bushing, and filler material 43 representing component
elements of the blade that is to be fabricated.
[0179] With reference to FIGS. 3 and 4, each former has a
pressure-side running surface 21, 31 and a suction-side running
surface 22, 32. Each running surface is U-shaped in horizontal
section seen in an elevation direction Z.
[0180] Furthermore, each running surface has a root zone Z1 with a
substantially vertical root wall 23, 33 that is C-shaped, in order
to make the spar of FIG. 1. This root wall thus forms a U-shaped
end wall 231, 331 of the running surface.
[0181] In addition, each running surface has a connection zone Z2
presenting two connection walls 24, 25 or 34, 35 that are offset
transversely, twisted, and respectively connected to two ends 232,
233, or 332, 333 of the end wall 231, 331 of the running
surface.
[0182] The two connection walls of the suction-side connection
surface of a former and the two connection walls of the
pressure-side connection surface of the former together generate a
lozenge-shape as seen in cross-section of the former.
[0183] Finally, each running surface has a running zone Z3
presenting two running walls 26, 27 or 36, 37 that are offset
transversely and connected respectively to the two connection walls
24, 25 or 34, 35.
[0184] In summary, each former has a suction-side running surface
of U-shape that comprises in succession a running wall referred to
as a "first suction-side running wall" 26, 36, a connection wall
referred to as a "first suction-side connection wall" 34, 24, a
root wall 23, 33, a connection wall referred to as a "second
suction-side connection wall" 25, 35, and a running wall referred
to as a "second suction-side running wall" 27, 37.
[0185] The first suction-side running wall 26, 36 forms an outer
suction-side zone 224. The second suction-side running wall 25, 35
forms an inner suction-side zone 223.
[0186] Under such circumstances, the first suction-side connection
wall 24, 34 and the second suction-side connection wall 27, 37
together form a suction-side connection zone.
[0187] Likewise, each former has a pressure-side running surface
that is U-shaped, comprising in succession a running wall referred
to as a "first pressure-side running wall", a connection wall
referred to as a "first pressure-side connection wall", a root
wall, a connection wall referred to as a "second pressure-side
connection wall", and a running wall referred to as a "second
pressure-side running wall".
[0188] The first pressure running wall forms an outer pressure-side
zone 222. The second pressure-side running wall forms an inner
pressure-side zone 225.
[0189] The first pressure-side connection wall and the second
pressure-side connection wall together form a pressure-side
connection zone.
[0190] Furthermore, and with reference to FIG. 3, the trailing-edge
former may include a pressure-side running surface 31 and a
suction-side running surface 32 that are vertically spaced apart
from each other.
[0191] In contrast, and with reference to FIG. 4, the leading-edge
former 20 is provided with a pressure-side running surface 21 and a
suction-side running surface 22 that meets so as to form a tip.
[0192] In addition, the outer suction-side zone 224 and the inner
suction-side zone 223 of the leading-edge former 20 are vertically
and transversely spaced apart by a suction-side step 226.
Similarly, the outer pressure-side zone 222 and the inner
pressure-side zone 221 are spaced apart vertically and transversely
by a pressure-side step 225.
[0193] Finally, the inner pressure-side zone 221 and the inner
suction-side zone 223 join together to form the tip of the
leading-edge former.
[0194] Under such circumstances, and with reference to FIG. 3, a
placement head can lay a U-shaped tape segment on the running
surface that does not face the plate 56' of the tooling. In order
to lay tape segments on the other running surface, it suffices to
pivot the former by using the pivot means 57, after previously
removing the pin 300.
[0195] During a fabrication step STP2, each arrangement is
subdivided into a pressure-side subassembly and a suction-side
subassembly.
[0196] Each subassembly then has at least one hank, each hank being
constituted by a stack of tape segments forming a U-shape that are
laid on a running surface of a former.
[0197] Each arrangement of the spar is then fabricated separately
and outside a mold for the blade.
[0198] The appropriate former is thus placed on the tooling. A
subassembly of the arrangement is then fabricated with the help of
the placement head, possibly while using the rocker.
[0199] The former is then turned over. The other subassembly of the
arrangement is then fabricated with the help of the placement head,
possibly while using the rocker.
[0200] Each subassembly is fabricated by stacking tape segments on
the former by means of a fiber placement method.
[0201] For example, the placement head 53 then winds each tape
segment of the pressure-side subassembly around a root axis AX1,
AX2 of the former while laying said segment on the pressure-side
running surface 21, 31. The placement head optionally winds each
tape segment of the pressure-side subassembly around a root axis by
following a U-shaped path. The placement head then lays a segment
over a first running wall of the pressure-side running surface, a
first connection wall of the pressure-side running surface, the
root wall, a second connection wall of the pressure-side running
surface, and a second running wall of the pressure-side running
surface.
[0202] Thereafter, the placement head 53 winds each tape segment of
the suction-side subassembly around a root axis AX1, AX2, laying
said segment on the suction-side running surface. For example, the
placement head winds each tape segment of the suction-side
subassembly around a root axis by laying said segment over a first
running wall of the suction-side running surface, a first
connection wall of the suction-side running surface, the root wall,
a second connection wall of the suction-side running surface, and a
second running wall of the suction-side running surface.
[0203] The hanks are optionally fabricated one after the other by
applying all of the segments of one hank on a former prior to
placing the segments of another hank.
[0204] In addition, the spar may have thickness that tapers
spanwise going away from a root axis.
[0205] In order to obtain this characteristic, and with reference
to FIG. 8, at least one tape segment 72 of a subassembly may cover
in the running zone another segment 71 of the subassembly across a
decreasing chord width 73.
[0206] In the variant of FIG. 9, at least one tape segment 74 of a
subassembly extends spanwise from a root axis over a first length
L1. Under such circumstances, at least one other segment 75 extends
spanwise from the root axis over a second length L2 that is
different from the first length L1, and in particular that is
shorter than the first length L1.
[0207] In the variant of FIG. 10, at least one segment 76 is offset
transversely relative to another segment 77 in the running
zone.
[0208] These variants can be combined.
[0209] With reference to FIG. 5, the leading-edge arrangement may
be made by alternating the laying of segments of a hank of the
pressure-side subassembly with laying segments of a hank of the
suction-side subassembly. Furthermore, the placement head acts in
the vicinity of the tip 28 of the leading-edge former to lay a
strand 82 of a hank against a previously-laid strand of the hank so
as to form a leading-edge herring-bone configuration 84.
[0210] This characteristic makes it possible to obtain a solid
leading edge.
[0211] For example, the placement head forms a first hank 91 of the
suction-side subassembly of the leading-edge arrangement.
[0212] This placement head thus organizes a plurality of tape
segments on the leading-edge former 20. It should be observed that
only the segments of the first hank are shown in order to avoid
overcrowding FIG. 5.
[0213] Each segment of the first hank 91 may have a first strand
81, a central strand 81b that can be seen in FIG. 6, and a second
stand 82 so as to impart a U-shape to the segment. Thereafter, the
placement head lays the first strand 81 on the outer suction-side
zone 224 and the suction-side connection zone, the central strand
81b on a suction-side root zone, and the second strand 82 on the
suction-side connection zone and the inner suction-side zone
223.
[0214] A suction-side portion 227 of the outer suction-side zone
224 leading to the suction-side step 226 is nevertheless not
covered by the first strand 81.
[0215] However, the second strand 82 projects transversely from the
inner suction-side zone 223.
[0216] Advantageously, the portion 821 of the first hank 91 that is
laid on the inner suction-side zone 223 is flush with the outer
suction-side zone 224.
[0217] Thereafter, the placement head forms a second hank 92 of the
pressure-side subassembly 11 with each segment of the second hank
comprising in succession a third strand 83 together with a central
strand 83b that can be seen in FIG. 6, and a fourth strand 84.
[0218] For each segment, the placement head lays the third strand
83 on the outer pressure-side zone 222 and a pressure-side
connection zone, the central strand 83b on a pressure-side root
zone, and the fourth strand 84 on the pressure-side connection zone
and on the inner pressure-side zone 221.
[0219] Nevertheless, a pressure-side portion 228 of the outer
pressure-side zone 222 leading to the pressure-side step 225 is not
covered by the third strand 83.
[0220] However, the fourth strand 84 projects transversely from the
inner pressure-side zone 221 so as to press against an edge of the
first strand 81.
[0221] The portion 841 of the second hank 92 that is laid on said
inner pressure-side zone 221 is flush with the outer pressure-side
zone 222.
[0222] The placement head then forms a third hank 93 of the
suction-side subassembly by organizing a plurality of segments on
said former, each segment of the third hank comprising in
succession a fifth strand 85 together with a central strand 85b
visible in FIG. 6, and a sixth strand 86.
[0223] For each segment, the placement head lays the fifth strand
85 jointly on the suction-side portion 227 and partially on the
second strand 82 in the running portion and then on the
suction-side connection zone. The central strand 85b is laid on the
suction-side root zone. In addition, the sixth strand 86 is laid on
the suction-side connection zone and then in the running zone on
the second strand 82 and on an edge of the fourth strand 84.
[0224] In addition, the sixth strand 86 projects transversely from
the fourth strand 84.
[0225] Finally, the placement head forms a fourth hank 94 of the
pressure-side subassembly by organizing a plurality of segments on
said former. Each segment of the fourth hank 94 comprises in
succession a seventh strand 87 together with a central strand 87b
visible in FIG. 6, and an eighth strand 88.
[0226] For each strand, the placement head lays the seventh strand
87 jointly on said pressure-side portion 228 and in part on the
fourth strand 84 in the running portion and then on the
pressure-side connection zone. The central strand is laid on the
pressure-side root zone. Finally, the eighth strand 88 is laid on
the pressure-side connection zone and then in the running zone on
the fourth strand 84 and against an edge of the sixth strand
86.
[0227] FIG. 6 is a diagram showing the resulting leading-edge
arrangement.
[0228] Furthermore, when the placement head has laid all of the
tape segments on a former, the arrangement is heated on the
former.
[0229] For a spar having two fastener bushings, the leading-edge
former and the trailing-edge former may be placed adjacent each
other and then heated together in order to polymerize or
consolidate the spar.
[0230] With reference to FIG. 11, an operator also fabricates a
mold 95 of the blade that is to be fabricated. The operator then
places the spar 5 in the mold 95.
[0231] The mold 95 is then placed in heater means in order to
polymerize or consolidate the blade 1.
[0232] Naturally, the present invention may be subjected to
numerous variations as to its implementation. Although several
implementations are described, it will readily be understood that
it is not conceivable to identify exhaustively all possible
implementations. It is known to be possible to envisage replacing
any of the means described by equivalent means without going beyond
the ambit of the present invention.
* * * * *