U.S. patent application number 14/796658 was filed with the patent office on 2016-01-14 for stabilized braided biaxial structure and method of manufacture of the same.
The applicant listed for this patent is A&P Technology, Inc.. Invention is credited to Victor Ivers, Phil Lariviere, Lucas Rice.
Application Number | 20160010248 14/796658 |
Document ID | / |
Family ID | 55064975 |
Filed Date | 2016-01-14 |
United States Patent
Application |
20160010248 |
Kind Code |
A1 |
Lariviere; Phil ; et
al. |
January 14, 2016 |
STABILIZED BRAIDED BIAXIAL STRUCTURE AND METHOD OF MANUFACTURE OF
THE SAME
Abstract
A flat broad good is manufactured from a portion of an
intermediate braided structure laid into flat broad good form. The
portion forming the flat broad good is a stabilized braided biaxial
structure.
Inventors: |
Lariviere; Phil; (Milford,
OH) ; Ivers; Victor; (Amelia, OH) ; Rice;
Lucas; (Loveland, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
A&P Technology, Inc. |
Cincinnati |
OH |
US |
|
|
Family ID: |
55064975 |
Appl. No.: |
14/796658 |
Filed: |
July 10, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62023445 |
Jul 11, 2014 |
|
|
|
Current U.S.
Class: |
87/7 ; 156/267;
156/60; 87/8 |
Current CPC
Class: |
D04C 1/12 20130101; D10B
2505/02 20130101; D04C 1/06 20130101 |
International
Class: |
D04C 1/12 20060101
D04C001/12; D04C 1/06 20060101 D04C001/06 |
Claims
1. A method of manufacturing a flat broad good comprising providing
an intermediate braided structure; and laying at least a portion of
the structure into flat broad good form; where the portion forming
the flat broad good is a stabilized braided biaxial structure.
2. The method of claim 1 where the intermediate braided structure
is a generally biaxially braided sleeve including at least two tow
materials in oblique directions and has at least one triaxially
braided region.
3. The method of claim 2 where the triaxial region includes
thermoplastic tow materials laid in a longitudinal direction.
4. The method of claim 3 where the thermoplastic tow materials laid
in a longitudinal direction are generally of lower strength as
compared to the tow materials in the oblique directions.
5. The method of claim 4 further comprising: applying heat to the
triaxial region of the structure to affect melting of the
longitudinal thermoplastic tow materials.
6. The method of claim 5 further comprising: slitting the
intermediate braided structure along a cut line in the triaxial
region.
7. The method of claim 6 further comprising: trimming away at least
one section of the triaxial region.
8. The method of claim 1 where the intermediate braided structure
is a generally biaxially braided tape including at least two tow
materials in oblique directions and has at least one triaxially
braided region.
9. The method of claim 8 where the triaxial region includes
thermoplastic tow materials laid in a longitudinal direction.
10. The method of claim 9 where the thermoplastic tow materials
laid in a longitudinal direction are generally of lower strength as
compared to the tow materials in the oblique directions.
11. The method of claim 10 further comprising: applying heat to the
triaxial region of the structure to affect melting of the
longitudinal thermoplastic tow materials.
12. The method of claim 11 further comprising: slitting the
intermediate braided structure along a cut line in the triaxial
region.
13. The method of claim 11 further comprising: trimming away at
least one section of the triaxial region.
14. The method of claim 1 further comprising: applying a matrix
soluble thermoplastic epoxy coating to at least one side of the
broad good; and heating the coating.
15. The method of claim 14 where the coating is heated to a full
cure.
16. The method of claim 1 where the intermediate braided structure
is generally biaxially braided including at least two tow materials
in oblique directions and has at least one triaxially braided
region including thermoplastic tow materials and processing tow
materials laid in a longitudinal direction.
17. An intermediate braided structure comprising: at least two tow
materials biaxially braided in oblique directions; and at least one
other tow material laid in a longitudinal direction forming a
triaxially braided region.
18. The intermediate braided structure of claim 17 where the
structure is a sleeve.
19. The intermediate braided structure of claim 17 where the
structure is a tape.
20. A braided biaxial structure, generally supplied as a broad
good, comprising: interleaved tows of material in opposing oblique
directions; and a matrix soluble thermoplastic epoxy coating on at
least one side of the structure.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims priority to and the benefit of U.S.
Provisional Patent Application No. 62/023,445 filed Jul. 11, 2014,
the contents of which are hereby incorporated by reference in their
entirety.
BACKGROUND
[0002] This relates generally to braided textile structures.
Braided textile structures are often embedded in a resin matrix to
form a final composite article and thereby act as reinforcement to
the final composite article and impart the final composite article
with certain predetermined and possibly varying tensile strengths
in different directions.
[0003] Braided biaxial structures are typically comprised of two
groups of tows of material laid into the structure in an
interleaving pattern wherein one group of tows is aligned along an
oblique direction relative to the longitudinal direction of the
structure and the other group of tows is aligned along an opposing
oblique direction. The opposing oblique directions and the
longitudinal direction are principal directions in the textile
architecture.
[0004] Braided textile structures are commonly manufactured in
generally cylindrical forms, such as sleeves, or flat forms, such
as tapes. In sleeve form the longitudinal direction lies along the
sleeve axis and the opposing oblique directions form opposing
helices wrapping around the longitudinal direction. In tape form,
the tows aligned along one oblique direction wrap around the edge
of the tape and the tow direction changes to the opposing oblique
direction until the wrapping around the opposing edge of the
tape.
[0005] A characteristic of a braided biaxial structure is that it
generally elongates in the longitudinal direction and contracts in
the transverse direction when subjected to longitudinal forces or
the longitudinal components of overall forces generally.
Conversely, the structure generally contracts in the longitudinal
direction and expands in the transverse direction when subjected to
transverse forces or the transverse components of overall forces
generally. The change in macroscopic geometry is generally due to
the interconnectedness of the interleaved groups of tows. The
corresponding geometric change within the structure may be
characterized by variations in the angles between tows lying in
oblique and longitudinal directions.
[0006] In one example, some braided biaxial sleeves can envelop and
conform to bodies of varying cross section. The conformability and
continuity of these sleeve structures around a body of varying
cross section provides for placement of tow materials along paths
may correspond to varying principal directions of the enveloped
body in a predetermined manner.
[0007] In another example, some braided biaxial tapes may generally
have less utility in this regard, as compared to some braided
biaxial sleeves, due to the structural discontinuity represented by
the edges of the tape.
[0008] While advantageous in some applications, this conformability
characteristic can be disadvantageous in other applications, for
example, when it is desired to maintain the orientation of the
oblique directions within a narrow tolerance range within regions
of the final composite article or across the entire article as a
whole. An example of one such application is large aerospace
structures including .+-.45 degree braided biaxial structure
reinforcements in a resin matrix.
[0009] In some applications of the example above, it is desired
that the behavior of the final composite structure be closely
approximated by the behavior of well-defined test structures. These
test structures generally include coupons with predetermined
dimensions and structure subjected to load, environmental and life
tests to develop a database of material properties. The material
properties of these structures are dependent on many factors and
composite structure designers must take care in ensuring that final
composite structures are similar enough to the test coupon
structures that the materials properties in the database can be
used with some level of confidence. In general, triaxial braided
structures, wherein the structure is comprised of two tows aligned
along opposing oblique directions and a third tow aligned along the
longitudinal direction, may be preferred in certain applications as
the longitudinal tows tend to lock the structure, restricting the
amount of deformation, and ensure that the structure deployed in
the final composite article will closely approximate the structure
of the test coupons.
[0010] In aerospace parts, which are highly scrutinized for weight
limitations, cost limits and other constraints, a triaxial
structure may not be optimum due to the additional material laid in
the longitudinal direction, particularly in applications where the
longitudinal material provides little to no additional desired load
carrying capability. A biaxial structure with low deformability
characteristics may be preferred to a triaxial structure for some
of these types of parts. For example, a biaxial structure with
limited, predictable deformability may be preferable for these
parts when a limited amount of drapability is required.
[0011] One example of a braided biaxial structure for some
applications includes tows of carbon or other high strength fiber
aligned along the opposing oblique directions and thermoplastic and
lower strength fibers, such as glass fibers, aligned along the
longitudinal direction. The glass material provides enough tensile
strength to facilitate manufacture of the braided structure without
undue distortion. The thermoplastic material may be melted, or
semi-melted, by application of heat and allowed to cool thereby
limiting the deformability of the braided structure. Development of
materials properties data relevant to said structures is costly and
time-consuming and few generally available materials properties
data are available. Therefore, these braided structures, though
generally not expected to deviate in properties from a biaxial
structure of similar material and geometric architecture, may not
be suitable for some applications. Therefore, there is a need for a
true biaxial structure that is stabilized such that distortion of
the braid is limited to a predetermined range allowing for use of
available materials properties data without incurring additional
testing.
SUMMARY
[0012] The present subject matter relates to stabilized braided
biaxial structures manufactured as flat broad goods. The present
subject matter also relates to a method of manufacture of these
structures.
[0013] A braided biaxial structure, generally supplied as a broad
good, includes interleaved tows of material in opposing oblique
directions and further includes a matrix soluble thermoplastic
epoxy coating on at least one side of the structure.
[0014] A method of manufacture includes a step where an
intermediate braided structure is manufactured in a conventional
sleeve form. The structure of the intermediate braided structure
may be generally biaxial and include at least one triaxial region.
The triaxial region may be formed from thermoplastic tow materials
laid in the longitudinal direction. The triaxial region may further
include materials laid in the longitudinal direction that are
generally of lower strength, and possibly also lower cost, as
compared to the tow materials in the oblique directions. It is
expected that the materials will carry tensile forces induced by
the manufacturing apparatus within the braided structure and
prevent distortion of the biaxial regions of the structure.
[0015] A method of manufacture may include a step where heat is
applied to a triaxial region of a structure to affect melting of
longitudinal thermoplastic fibers thereby limiting distortion of a
biaxial region of the structure during subsequent manufacturing
steps.
[0016] A method of manufacture may include a step where a matrix
soluble thermoplastic epoxy coating is applied to at least one side
of a broad good and heated to solidify the coating. The duration
and intensity of heat may be controlled so as to prevent cure of
the coating and retain the coating as matrix soluble for when a
braided biaxial structure is deployed as reinforcement in a
composite article.
[0017] A method of manufacture may include a step to trim away a
triaxial region or regions of a structure resulting in a stabilized
braided biaxial structure that may withstand tensile forces applied
during deployment as reinforcement in a composite article without
distortion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a plan view of a stabilized braided biaxial
structure.
[0019] FIG. 2 is a transverse cross sectional view of a portion of
the stabilized braided biaxial structure of FIG. 1.
[0020] FIG. 3 is a front view showing an intermediate braided
structure in the manufacture of the stabilized braided biaxial
structure of FIG. 1.
[0021] FIG. 4 is a plan view of the intermediate braided structure
of FIG. 3 in a slit state.
[0022] FIG. 5 is a flowchart of a method of manufacture of the
stabilized braided biaxial structure of FIG. 1.
[0023] FIG. 6 is a view similar to FIG. 3 showing an intermediate
braided structure according to another embodiment.
[0024] FIG. 7 is a flowchart of a method of manufacture of a
stabilized braided biaxial structure incorporating the intermediate
braided structure of FIG. 6.
[0025] FIG. 8 is a schematic illustration of the applying and
curing of thermoplastic epoxy coating of the method of FIG. 5.
[0026] FIG. 9 is a schematic illustration of the curing of
thermoplastic epoxy coating according to another embodiment.
[0027] FIG. 10 is a plan view of the intermediate braided structure
of FIG. 6 in a slit state.
[0028] FIG. 11 is a schematic view of a multilayer lamination
process according to a further embodiment.
[0029] FIG. 12 is a schematic view of an application of epoxy
according to yet another embodiment.
DETAILED DESCRIPTION
[0030] As used in the disclosure, a "braided structure" is a
structure including a plurality of strands of material, commonly
called tows, such that each tow is intertwined with at least one
other tow in a repeating pattern. Two-dimensional braided materials
are those wherein the repeating pattern is largely characterized by
two or more principal weave directions all in a common plane,
typically the longitudinal direction of the braided structure,
commonly called the axial direction, and one or more oblique
directions, commonly called bias directions, each at a
predetermined angle to the longitudinal direction.
Three-dimensional braided structures are those wherein additional
principal directions, generally mutually perpendicular to the
longitudinal and oblique directions, are required to completely
define the structure and the patterns thereof. For simplicity of
description, these additional directions are generically referred
to as radial directions, whether the structure is generally tubular
in form, laid out as a flattened tubular form or in a fabric, or
generally planar, form. Herein, reference to braided structure
generally implies two-dimensional forms but does not exclude
three-dimensional forms.
[0031] Two-dimensional braided structures may be manufactured as
generally cylindrical materials, commonly called sleeves, with the
axial direction corresponding to the longitudinal axis of the
cylinder and the bias directions oblique to the longitudinal axis.
Braided structures manufactured in cylindrical form may then be
laid-flat to form a two-dimensional fabric comprised of two layers
joined along the longitudinal edges. The edges may be removed to
form two separate and distinct layers. One edge may be removed and
the cylindrical structure laid-flat to form a singly-slit single
layer structure. Two edges may be removed to form a double-slit
two-layer structure. Two-dimensional braided structures may further
be manufactured in a single layer flat form, commonly called a
tape.
[0032] In the art, the terms "strand", "tow", "yarn", "yarn
bundle", "fiber" and "fiber bundle" are generally meant to describe
what is laid into or intertwined in each of the principal
directions of a braided structure. In this disclosure, the term
"tow" will generally be used to describe what is laid into or
intertwined in each of the principal directions of a braided
structure. A tow is an amalgamation of all material that runs
together in a principal direction. A tow can comprise
monofilaments, multiple filaments or be comprised of staple, or
spun, material. Tow material can have a variety of cross-sectional
shapes, including but not limited to, generally circular,
ellipsoidal, triangular, and flat tape shapes. Tow material may be
subject to intermediate or pre-processing prior to braiding
operations. Examples of intermediate or pre-processing may include,
but are not limited to, twisting, braiding small numbers of
filaments into braided tow materials, pre-impregnation with resins
and specialty coating to facilitate braiding and/or subsequent
processing. A tow can comprise any combination of these materials
and material forms. Any one tow may comprise one or more filament
or staple materials. A tow may be comprised of carbon materials,
basalt, glass materials, thermoplastic polymeric materials,
thermoset polymeric materials, a combination of carbon and
polymeric materials or a combination of polymeric and glass
materials, or some combination thereof, and other suitable
materials. Tows that lay in one of the bias directions of the
fabric are commonly called bias tows. Tows that lay in the axial
direction of the fabric are commonly called axial tows.
[0033] Biaxial braid is generally formed from bias tows. Triaxial
braid generally includes bias and axial tows. Hybrid braided
structure may be formed of contiguous materials including one or
more adjacent regions of biaxial and triaxial braid.
[0034] Referring now to the drawings, there is illustrated in FIG.
1 a stabilized braided biaxial structure 11 with principal
longitudinal direction 12 and opposing oblique directions 13 and
14. Illustrated in part, a first group of tows 15 are aligned along
the first oblique direction 13 and a second group of tows 16 are
aligned along the second oblique direction 14.
[0035] As best shown in FIG. 2, the stabilized braided biaxial
structure 11 includes a matrix soluble thermoplastic epoxy coating
21 affixed to one surface of the braided biaxial structure 11.
[0036] There is shown in FIG. 3 an intermediate braided structure
31 formed in a process for manufacturing the braided biaxial
structure 11. As illustrated, the intermediate braided structure 31
is a hybrid structure in sleeve form including a biaxial region 32
and a triaxial region 33 with thermoplastic tows 34 laid in along
the longitudinal direction. Processing tows 35 may also be laid
into the longitudinal direction along with the thermoplastic tows
34. The amalgamation of thermoplastic tows 34 and processing tows
35 may herein be referred to commonly as longitudinal tows 34, 35.
In the process of manufacture, a method for which is further
described below, the intermediate braided structure 31 may be slit
along a cut line, indicated at 36, and then laid flat to form an
intermediate broad good 41, as shown in FIG. 4, with central
biaxial region 42 formed from the biaxial region 32 and edge
triaxial regions 43 formed from the triaxial region 33.
[0037] There is illustrated in FIG. 5 a method 50 for the
manufacture of a stabilized braided biaxial structure. In a first
step 51, an intermediate braided structure of hybrid form with
biaxial and triaxial regions is manufactured. The triaxial region
includes axial or longitudinal tows comprised of thermoplastic
fibers and may also include processing tows. It is expected that
the processing tows will reduce distortion in the biaxial region
due to tensile forces imposed on the structure during
manufacture.
[0038] In a second step 52, heat is applied to the axial tows in
the triaxial region of the structure to melt the thermoplastic tow
materials thereby affixing in place the portions of the bias tows
passing through the triaxial region.
[0039] In a third step 53, the intermediate braided structure is
slit along a cut line in the triaxial region.
[0040] In a fourth step 54, the intermediate braided structure is
laid flat into a broad good form.
[0041] In a fifth step 55, a matrix soluble thermoplastic epoxy
coating is applied to at least one surface of the broad good form.
The matrix soluble thermoplastic epoxy coating may be applied in
powder or liquid form.
[0042] In a sixth step 56, heat is applied to the matrix soluble
thermoplastic epoxy coating to solidify the coating with or without
curing the resin. The solidified matrix soluble thermoplastic epoxy
coating serves to lock the orientation of the bias tows in the
biaxial region of the braided structure.
[0043] In a seventh step 57, the triaxial regions of the structure
are trimmed off thereby leaving a stabilized braided biaxial
structure.
[0044] In an alternative method of manufacture may also include an
optional step, not shown, between laying the slit sleeve flat, the
fourth step 54, and applying the matrix soluble thermoplastic epoxy
coating, the fifth step 55, where the laid flat broad good is wound
onto a reel and the reel is then moved to another set of
apparatuses for performance of subsequent steps.
[0045] An alternative intermediate braided structure 61 is shown in
FIG. 6. The alternative intermediate braided structure 61 is a
hybrid structure in sleeve form and includes at least two biaxial
regions 62 and at least two triaxial regions 63. In a method of
manufacture for the alternative intermediate braided structure 61,
the alternative intermediate braided structure 61 may be slit along
cut lines 64 and the resulting sections laid flat to each form an
intermediate broad good similar to that shown in FIG. 4.
[0046] There is illustrated in FIG. 7 another method 70 for the
manufacture of a stabilized braided biaxial structure. The method
70 may utilize the intermediate braided structure 61 of FIG. 6.
[0047] The method 70 includes a first step 71 an intermediate
braided structure of hybrid form with at least two biaxial regions
and at least two triaxial regions is manufactured. Each triaxial
region includes axial or lateral tows including thermoplastic
fibers and may also include processing tows. It is expected that
the processing tows will reduce distortion in adjacent biaxial
regions due to tensile forces imposed on the structure during
manufacture.
[0048] In second step 72, heat is applied to the axial tows in each
triaxial region of the structure to melt the thermoplastic tow
materials thereby affixing in place the portions of the bias tows
passing through each triaxial region.
[0049] In third step 73, the intermediate braided structure is slit
along a cut line in each triaxial region.
[0050] In a fourth step 74, each resultant section of the structure
is laid flat
[0051] In a fifth step 75, a matrix soluble thermoplastic epoxy
coating is applied to at least one surface of each resultant
section of the structure. The matrix soluble thermoplastic epoxy
coating may be applied in powder or liquid form.
[0052] In a sixth step 76, heat is applied to the matrix soluble
thermoplastic epoxy coating on each resultant section to solidify
the coating with or without curing the resin.
[0053] In a seventh step 77, the triaxial regions of each resultant
section of the structure are trimmed off thereby leaving each
resultant section of the structure as a stabilized braided biaxial
structure.
[0054] There is illustrated in FIG. 8 one process of applying
thermoplastic epoxy coating. In the illustrated process, epoxy is
transferred to a braided material 81 by utilization of gravity
application. The process includes the braided material 81 passing
through an epoxy application chamber 82, wherein uncured epoxy is
released from an epoxy depositor 83 and transferred to the braided
material 81 via gravity feed, as shown at 84, and thus accumulating
on the surface of the braided material 81. The applied uncured
epoxy 85 on the braided material 81 travels past a heater 86 which
cures the thermoplastic epoxy from an uncured state, as shown at
85, to semi-cured state, as shown at 87, and optionally to a
fully-cured state, as shown at 88, thus producing a stabilized
biaxial braided structure.
[0055] There is illustrated in FIG. 9 a thermoplastic curing
process. In the illustrated process, braided material 91 has
uncured thermoplastic epoxy 92 applied. The uncured epoxy 92 on the
braided material 91 travels past a heater 93 which cures it from an
uncured state 92, to semi-cured state 94, and optionally to a fully
cured state 95, producing a stabilized biaxial braided
structure.
[0056] An alternative method of manufacture may include a step
where a resultant section is wound onto a reel and the reel is then
moved to another set of apparatuses for performance of subsequent
steps. Such a step may occur between laying the resultant section
flat and applying the matrix soluble thermoplastic epoxy coating to
the resultant section.
[0057] Another alternative method of manufacture may include
manufacturing an intermediate braided tape structure, as opposed to
an intermediate braided sleeve structure, with triaxial regions as
described in the methods above. The intermediate braided tape
structure may include triaxial regions along both edges of the tape
and biaxial region between the two edges. A mechanism may be
utilized to ensure the orientation of the bias tows after the
braided tape structure has fully formed. The mechanism may be
crowned rollers, bowed rollers, tension adjustment mechanisms, and
or any other suitable mechanisms. Once the intermediate braided
tape structure is manufactured, heat may be applied to the triaxial
regions to melt the thermoplastic tow materials and lock the edges
of the tape. Following, a matrix soluble thermoplastic epoxy
coating may be applied and solidified and then the triaxial regions
trimmed away.
[0058] An alternate embodiment of the method of manufacture
utilizing an intermediate tape structure comprises an intermediate
tape structure with at least two biaxial regions and three triaxial
regions slit into at least two structures. As best shown in FIG.
10, the intermediate tape structure 100 consists of triaxial
regions 101 and biaxial regions 102. Within the central triaxial
region 101 is a cut line 103 for further processing and separation
of sections of the tape structure 100 (shown as consisting of a
biaxial regions paralleled with a triaxial regions).
[0059] Other alternate embodiments may include applying and heating
thermoplastic film over regions of biaxial braid to fix or lock the
orientation of the bias tows in place of thermoplastic tow
materials laid into the braid. Thermoplastic films may also remove
the need for processing tow materials laid into the biaxial regions
where cuts will be made.
[0060] Further alternate embodiments may include multi-layer
lamination of braid materials as shown in FIG. 11. An initial
braided material layer 111, for example un-stabilized biaxial
braided material layer, receives uncured thermoplastic epoxy 112a.
The initial braided material layer 111 with the thermoplastic epoxy
112a travels past a primary heater 113a, producing a semi-cured
epoxy 114a. While the epoxy is in a semi-cured state as semi-cured
epoxy 114a, an additional layer of braided material 116, for
example another un-stabilized biaxial braided material layer, is
applied to the initial layer 111. The heater 113a further cures the
epoxy to a fully-cured state epoxy 115a, generally bonding the two
layers 111 and 116 together. An additional layer of thermoplastic
epoxy 112b may be added to the additional braid layer 116. The
additional braided material layer 116 may then receive uncured
thermoplastic epoxy 112b. The additional braided material layer 116
with the thermoplastic epoxy 112b may then travel past a second
heater 113b, producing a semi-cured epoxy 114b. The second heater
113b may further cure the epoxy with to a fully-cured state epoxy
115b, generally bonding the two layers 111 and 116 together.
Further optional layers of braid or epoxy may be added to further
stabilize or reinforce the resultant product. While the above
heating was described with two heaters, it must be understood that
the heating may be performed by one heater or any number of
multiple heaters.
[0061] Another alternate embodiment includes application of an
epoxy through fluid assistance. As shown in FIG. 12, as braided
material 121 passes into an epoxy application chamber 122, uncured
thermoplastic epoxy 124 is released by an epoxy depositor 123. The
uncured thermoplastic epoxy 124 may be generally dispersed via
gravity. During descent of the uncured thermoplastic epoxy 124,
fluid nozzles 125, which are preferably offset, deliver a
pressurized fluid into the chamber 122. The fluid may be or include
an inert gas or atmospheric fluid. The offset angle of the nozzles
and velocity of the fluid causes the gravity-dispersed epoxy 124 to
become suspended in the chamber 122. The suspended epoxy 126 may be
transferred to the braided material 121, by the theory that the
braided material 121 is a semi-permeable structure allowing fluid
from the pressurized chamber 122 to pass through yet capture
suspended epoxy 126 on the braided material 121, creating an
uncured epoxy layer 127. This method allows for application of
atmospheric sensitive epoxies and even coverage regardless of
process orientation.
[0062] Additional other alternate embodiments may include using a
matrix soluble thermoplastic epoxy in place of thermoplastic tow
materials or thermoplastic films, with or without processing tow
materials. Further alternate embodiments replacing thermoplastic
tows or film with the matrix soluble thermoplastic epoxy may
include steps to apply the coating across the entire braided
structure once the braid is formed and then to apply heat only
where cuts will be made, laying the structure or sections of the
structure flat and then to apply heat across the entire surface or
surfaces to lock the structure or structures in place. These
alternate embodiments may exclude a step of trimming away regions
of material employed to hold the structure in place until the
matrix soluble thermoplastic epoxy coating is solidified, thereby
increasing production yield.
[0063] While principles and modes of operation have been explained
and illustrated with regard to particular embodiments, it must be
understood, however, that this may be practiced otherwise than as
specifically explained and illustrated without departing from its
spirit or scope.
* * * * *