U.S. patent application number 12/560599 was filed with the patent office on 2010-01-07 for apparatus and method for making preforms in mold.
This patent application is currently assigned to BRUNSWICK CORPORATION. Invention is credited to Christian W. Anderson, Scott A. Lammers, Steve H. Olson, Jonathan W. Schacher.
Application Number | 20100003416 12/560599 |
Document ID | / |
Family ID | 34396275 |
Filed Date | 2010-01-07 |
United States Patent
Application |
20100003416 |
Kind Code |
A1 |
Lammers; Scott A. ; et
al. |
January 7, 2010 |
Apparatus and Method for Making Preforms in Mold
Abstract
Apparatus and a method of preparing fiber preforms disperses
fibers and binder on a forming support surface such that the
materials are conditioned and then applied to the surface where the
composite material solidifies. Reinforcing material, such as fiber,
is mixed with binder, such as thermoplastic or thermoset materials,
so that the materials adhere. Then, the adhesive mixture is
dispersed in a controlled predetermined weight ratio on the support
surface where the mixture sticks to the support surface, cools and
solidifies. The deposited mixture can be an open mat having
interstices between fibers. The deposited mixture can also be
shaped further into a final desired shape before complete
solidification. This method eliminates the need for solvents and
their associated problems. The process does not require a vacuum or
plenum system to hold the reinforcing material in place. The
preform can be made in any shape, including sections or asymmetric
configurations and remain in mold while being processed to a
composite molded article.
Inventors: |
Lammers; Scott A.;
(Knoxville, TN) ; Schacher; Jonathan W.; (Lenoir
City, TN) ; Anderson; Christian W.; (Seymour, TN)
; Olson; Steve H.; (Knoxville, TN) |
Correspondence
Address: |
FITCH, EVEN, TABIN & FLANNERY
P. O. BOX 18415
WASHINGTON
DC
20036
US
|
Assignee: |
BRUNSWICK CORPORATION
LAKE FOREST
IL
|
Family ID: |
34396275 |
Appl. No.: |
12/560599 |
Filed: |
September 16, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11391256 |
Mar 29, 2006 |
7597760 |
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12560599 |
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10947543 |
Sep 23, 2004 |
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11391256 |
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60505838 |
Sep 26, 2003 |
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Current U.S.
Class: |
427/374.4 |
Current CPC
Class: |
B29C 70/305 20130101;
B29L 2031/307 20130101; B29K 2105/06 20130101; B29K 2223/0683
20130101; B29B 11/16 20130101 |
Class at
Publication: |
427/374.4 |
International
Class: |
B05D 3/02 20060101
B05D003/02 |
Claims
1-24. (canceled)
25. A method of making a preform for use in forming a structural
part, comprising: providing a stream of fibrous reinforcing
material; adhering particulate binder material to the reinforcing
material by combining a stream of binder material to the stream of
fibrous reinforcing material in a venturi device to form an
adhesive mixture; and applying the adhesive mixture of the
reinforcing material and the binder material from said venturi
through a heating zone and against a support surface, optionally
applying a stream of gaseous cooling media to the material sprayed
on said surface, such that the mixture adheres to the support
surface, and solidifies into the preform.
26. The method of claim 25, wherein said applying said adhesive
mixture comprises spraying and said method includes applying said
stream of gaseous cooling media by passing a cooling air curtain
over the adhesive mixture sprayed on the support surface.
27. The method of claim 26, wherein said spraying and said cooling
occur in the absence of a plenum system applied about or to the
support surface.
28. The method of claim 25, wherein adhering binder material to the
reinforcing material includes conditioning the binder material with
heat and forcing the conditioned binder material into the stream of
reinforcing material.
29. The method of claim 26, wherein said spraying includes creating
a heating zone and feeding the adhesive mixture through the heat
zone.
30. The method of claim 28, wherein providing a stream of fibrous
material includes blowing chopped fiberglass.
31. The method of claim 26, wherein spraying the adhesive mixture
includes spraying the mixture onto a vertical support surface.
32. The method of claim 26, wherein spraying the adhesive mixture
includes spraying the mixture onto a solid surface.
33. The method of claim 26, wherein spraying the adhesive mixture
includes spraying the mixture onto a perforated surface.
34. The method of claim 26, wherein spraying the adhesive mixture
includes spraying the mixture onto the support surface under
ambient air conditions.
35-47. (canceled)
Description
FIELD OF THE INVENTION
[0001] This invention relates to an apparatus and a method of
making a preform, particularly for use in composite molded
articles, and also composite molded articles. The apparatus and the
method especially relate to making a structural preform for use
with polymeric materials.
BACKGROUND OF THE INVENTION
[0002] High strength polymeric materials are being increasingly
used to replace traditional structural materials, such as metal, in
many applications. The polymeric materials have the advantage of
lower weight and are often less expensive and more durable than
metals. However, polymeric materials tend to be much lower in
strength than metal. Unless polymeric materials are reinforced in
some manner, they often do not meet the strength requirements for
metal replacement.
[0003] Thus, polymeric composites have been developed to meet such
strength requirements. These composites are characterized by having
a continuous polymeric matrix within which is embedded a
reinforcement material, which is usually a relatively rigid, high
aspect ratio material such as glass fibers.
[0004] Such composites are typically molded into a predetermined
shape, which is in many cases asymmetric. To place the
reinforcement material into the composite, the reinforcement
material is usually placed into the mold in a first step, followed
by closing the mold and then introducing a fluid molding resin. The
molding resin fills the mold, including the interstices between the
fibers, and hardens (by cooling or curing) to form the desired
composite. Alternatively, the molding resin can be applied to the
reinforcing fiber prior to molding. The reinforcing fiber with
resin thereon is then placed into a mold where temperature and
pressure are applied, curing the resin to prepare the desired
composite.
[0005] It is desirable to uniformly distribute the reinforcement
material throughout the composite. Otherwise, the composite will
have weak spots where the reinforcement is lacking. Thus, it is
important to prepare the reinforcement material so that the
individual fibers are distributed evenly throughout the composite.
In addition, the individual fibers should be held in place to
resist flowing with the molding resin as it enters the mold, which
would disrupt the fiber distribution.
[0006] For these reasons, reinforcement has been conventionally
formed into a mat outside of the mold. The preform mat is then
placed in the mold and either impregnated with resin to make the
final composite article, or simply heated and pressed to make a
very low density composite article. The mat is generally prepared
by forming the reinforcing fibers into a shape matching the inside
of the mold and applying a binder to the fibers. In some instances,
a thermosetting binder is pre-applied, and then cured after the
fibers are shaped into a mat.
[0007] In other methods, a thermoplastic binder is applied, so that
in a subsequent operation the binder can be heated and softened and
the mat subsequently shaped. This binder "glues" the individual
fibers to each other so that the resulting mat retains its shape
when it is transferred to the mold for further processing. The
binder also helps the individual fibers retain their positions when
the fluid molding resin is introduced into the mold. In some cases,
a molding resin can alternatively be applied to the reinforcing
fiber prior to molding. The fiber with binder and resin is placed
into a mold where temperature and pressure are then applied, curing
the resin to prepare the desired composite.
[0008] Binders conventionally used have been primarily of three
types, each of which have various drawbacks. The predominantly used
binders have been solvent-borne polymers, i.e., liquids, such as
epoxy and polyester resins. The solvent-borne binders are usually
sprayed onto the mat via an "air-directed" method, and then the mat
is heated to volatilize the solvent and, if necessary, cure the
binder. This means that the application of binder is at least a
two-step process, which is not desirable from an economic
standpoint. Also, the use of solvents is encountered, which raises
environmental, exposure and recovery issues. Dealing with these
issues potentially adds significantly to the expense of the
process. The procedure is also energy intensive, as the entire mat
must be heated just to flash off solvent and cure the binder. The
curing step also makes the process take longer.
[0009] Use of the solvent-borne polymer binders is extremely messy.
There are also high maintenance costs associated with keeping the
work area and the screen on which the mat is formed clean. In this
case, where the binder may be low viscosity fluid, it tends to flow
over and coat a large portion of the surface of the fibers. When a
composite article is then prepared from a preform made in this way,
the binder often interferes with the adhesion between the fibers
and the continuous polymer phase, to the detriment of the physical
properties of the final composite.
[0010] A second form of binder is powdered binders. These can be
mixed with the fibers, and then the mass formed into a preform
shape, which is heated to cure the binder in situ. Alternatively,
these binders can be sprayed to contact the fibers. However, simply
substituting a powdered binder in an air-directed method raises
problems. For example, powdered binders cannot be applied unless a
veil is first applied to the screen to prevent the binder particles
from being sucked through. Again, this adds to the overall cost and
adds a step to the process. Airborne powders may also present a
health and explosion hazard, depending on conditions of use. The
use of powdered binders additionally requires a heating step to
melt the binder particles after they are applied to the fibers.
Heating renders this process energy-intensive.
[0011] Binders of a third type are heated thermoplastic materials,
which can be melted and sprayed as a binder. Use of these materials
makes any subsequent heating step unnecessary, since the binder
does not require heat to achieve some undetermined measure of
adhesion to the fibers. This method has problems with "lofting," or
inadequate compaction of the preform. Lofting typically occurs
because the thermoplastics are conventionally heated to any random
temperature above their melting points, leading to a lack of
uniformity in their cooling patterns and extensive migration along
fiber surfaces. This allows some of the fibers to "bounce back"
before they are set into place by the solidifying thermoplastic.
This may result in formation of a lower density preform than
desired, density gradients throughout the preform, and poor
adhesion of the fibers to each other.
[0012] In view of the problems discussed herein, one prior art
method disclosed in U.S. Pat. No. 6,030,575, which is incorporated
herein by reference, applies a heated binder to fibers already
supported on a support surface while a vacuum is applied to the
other side of the support surface. By this method, the fibers are
held in place by the vacuum while the binder is applied at a high
pressure by a spray device. This application applies pressure to
the fibers thus forming a solid reinforcing structure. Upon
application, and with the assistance of the air flow from the
vacuum, the binder cools and solidifies into the desired preform
shape. However, the application of the vacuum requires additional
equipment in the form of a plenum arrangement and also requires
additional control functions and labor to properly apply the fibers
and vacuum. Therefore, the material and operating costs are
increased.
[0013] In view of these prior art methods, it would be desirable to
provide a simpler apparatus and a method for making preforms in
which the problems associated with using solvent-borne, powdered or
thermoplastic binders are minimized or overcome. It would also be
desirable to provide apparatus and a method in which sagging,
slumping, and separating of perform materials from tall vertical or
nearly vertical surfaces is avoided. It would also be desirable to
provide a lower cost method that is simple to operate and thus more
conducive to automation. In a more simple forming process, it may
even be possible to eliminate the need to transfer the preform to a
molding tool and/or eliminate the need to apply a vacuum to the
forming surface.
SUMMARY OF THE INVENTION
[0014] An aspect of this invention provides an apparatus and a
method in which a high strength structural preform and composite
molded article can be made efficiently and at a lower cost.
[0015] Another aspect of this invention provides an apparatus and a
method of making a preform and/or a composite molded article that
does not require the use of an additional amount of organic
solvents.
[0016] A further aspect of this invention provides an apparatus and
a method of making a preform and/or a composite molded article that
can assume a variety of shapes, including asymmetric parts or
portions of parts.
[0017] An additional aspect of this invention provides an apparatus
and a method that uses less components and thus reduces the capital
entry and operational production costs.
[0018] This invention can be easily adapted to automated production
and/or control.
[0019] A method in accordance with this invention comprises the
steps of providing reinforcing material, providing binder material,
mixing the reinforcing material and the binder material so that the
binder material adheres to the reinforcing material, applying a
stream of the mixture to a support surface thereby adhering the
mixture to the support surface, and solidifying the mixture to form
the preform.
[0020] In particular, the method relates to making a preform for
use in forming a structural part in which a stream of fibrous
reinforcing material is provided, particulate or liquid or atomized
binder material is adhered to the reinforcing material by providing
a stream of binder material into the stream of fibrous reinforcing
material in a venturi to form an adhesive mixture, and the adhesive
mixture of the reinforcing material and the binder material is
thermal sprayed against a support surface, optionally sequentially
cooled by applying cooling media to the just thermally sprayed and
deposited adhesive mixture, such that the mixture adheres to the
support surface and solidifies into the preform.
[0021] Preforms and composite molded articles made in accordance
with the method and its variations described herein are also
encompassed by this invention.
[0022] It is to be understood that the invention described herein
can be varied in a number of ways and is not restricted to the
particular embodiments described herein. The invention is intended
to generally include any embodiment in which the fiber and binder
material is combined prior to application to the surface where it
then solidifies in the desired shape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The invention will be described in greater detail in
conjunction with the following drawings wherein:
[0024] FIG. 1 is a schematic perspective view of an end effector
depositing the material onto a surface to make a preform in
accordance with an aspect of this invention;
[0025] FIG. 2 is a schematic perspective view of a preform being
made in accordance with an aspect of this invention;
[0026] FIG. 2A is an enlarged partial section of one type of
forming surface for use with the method in accordance with the
invention;
[0027] FIG. 2B is an enlarged partial section of another type of
forming surface for use with the method in accordance with the
invention;
[0028] FIG. 2C is an enlarged partial section of another type of
forming surface for use with the method in accordance with the
invention;
[0029] FIG. 2D is an enlarged partial section of a preform formed
by a method in accordance with the invention;
[0030] FIG. 3 is a partial side view of an end effector for use
with an embodiment of the method in accordance with the
invention;
[0031] FIG. 4 is a partial perspective view of an end effector of
FIG. 3;
[0032] FIG. 5 is a partial side perspective view of an end effector
for use with an embodiment of a method in accordance with the
invention;
[0033] FIG. 6 is a partial perspective view of an end effector
showing provided with elements for applying a curtain of cooling
media;
[0034] FIG. 7 is a partial end view of an end effector and the
arrangement for providing a curtain of cooling media;
[0035] FIG. 7A is a cut away in cross section of a pair of venturi
apparatus;
[0036] FIGS. 8 and 8a and FIGS. 8c and 8d are respectively a
partial view of a chopper gun assembly mounted on an end effector
of FIG. 6 and a partial view of a chopper gun detached from an end
effector of FIG. 6;
[0037] FIG. 9 depicts an end effector with heaters in operation to
generate a heating zone and a mixture of reinforcing fibers plus
binder streaming through the heating zone;
[0038] FIG. 10 depicts an end effector mounted on a robotically
controlled arm being used in making a preform for a boat hull;
[0039] FIG. 11 photographically depicts a robotically controlled
arm having an end effector being used in applying fiber/binder in
to a gel coated mold tool;
[0040] FIG. 12 photographically depicts a boat hull preform,
obtained in a first mold tool after completing fiber/binder
application according to FIG. 11;
[0041] FIG. 13 photographically depicts a boat hull preform in a
first mold tool in which the perform is trimmed for subsequent
fabrication to a finished composite molded article;
[0042] FIG. 14 photographically depicts a trimmed boat hull preform
in a supported first mold tool with a matching second mold tool
shown in an open position, before initiating resin transfer molding
to manufacture a composite molded article; and
[0043] FIG. 15 illustrates the use of more than one end effector in
the fabrication of a preform.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0044] This invention is described below with reference to
formation of a preform for use in the marine industry to construct
fiberglass reinforced articles, such as a motor box for a boat, a
hatch, deck, deck section or a boat hull. However, it is to be
understood that this is an exemplary embodiment only and that the
method can be applied in various applications in which high
strength structural members are used. For example, a preform made
in accordance with the disclosed embodiments of the invention could
be used in the automotive, aircraft, or building industries or as a
component of household goods, such as appliances. Further, although
specific examples of materials are provided herein, any suitable
material can be used.
[0045] As seen in FIG. 1, a preform making assembly 10 used to
practice a method in accordance with the invention includes a
materials applicator 12 that applies the preform material mixture
14 to a support surface 16 to create preform 18. The term preform
in this application is intended to cover any structure used as a
reinforcing insert or structural support within a composite
structural part, which is preferably, but not necessarily, a molded
part. Such a preform 18 can be used while remaining in a mold.
Preform 18 could be formed and either used while remaining in its
mold or placed within a closed mold or on an open mold (a tray or
base, for example) to form the composite part. Alternatively,
preform 18 could be used as a base structure having materials
attached or molded to it, thus acting as a skeleton or tray and
eliminating the need for a mold base or molding tool. Preform 18
can be any desired shape. In its simplest form, it resembles a
shaped mat.
[0046] Materials applicator 12 in FIG. 1, includes a robotically
controlled arm 20 with an end effector 22 that delivers the preform
materials mixture 14 to support surface 16. Preform materials
mixture 14 can be applied by end effector 22 by any known
application method, including for example, spraying, blowing,
streaming, ejecting, laminating, or draping.
[0047] As seen in FIG. 1, support surface 16 can be any surface
including an entire part shape or portions of a part. Support
surface 16 can include surfaces oriented in any plane. This method
is particularly suited for applying material to a vertical surface
24. FIG. 2, for example, shows a preform 18 shaped as an entire
boat hull, which can serve as a free standing structural base
during molding. In this case, preform materials mixture 14 applied
to support surface 16 includes randomly oriented chopped glass
fibers retained by a thermoplastic binder, as seen in FIG. 2D.
[0048] As will be recognized, support surface 16 can be made of any
suitable material, including fiberglass, metal or ceramic,
especially materials known for use in molding tools. The surface
can also be pretreated if desired. For example, if preform 18 will
be used merely by compressing and heating the preform without
additional molding steps, it may be desirable to powder coat
support surface 16. Also, surface treatments used for molding can
be employed, such as a gel coat, mold release agent, peel shell or
veil, used alone or in various combinations. Obviously, the
intended use of preform 18 can dictate the precise configuration of
support surface 16.
[0049] FIGS. 2A-2C show variations of support surface 16 usable
with the method in accordance with embodiments of the invention.
Support surface 16 can be a perforated plate-like member 26 with
apertures 28, as seen in FIG. 2A, which allows air to flow through
apertures 28 in member 26 during application. Although, as
described below, there is no controlled air flow at support surface
16, ambient air trapped between support surface 16 and mixture 14
during application can escape through apertures 28, thus providing
more control during application of mixture 14 and a more compact
preform 18.
[0050] Alternatively, support surface 16 can be a stiff mesh 30 as
seen in FIG. 2B. In this embodiment, mixture 14 can adhere to mesh
30 and integrate mesh 30 into the preform structure, thus adding
rigidity. Mesh 30 also has the additional advantage of allowing
ambient air to flow through its apertures during application of
mixture 14. Mesh 30 can be any suitable material, including
fiberglass, plastic, metal, wood or any combination thereof. Mesh
30 offers advantages during subsequent molding by providing
interstices into which later applied resin can flow and bind.
[0051] FIG. 2C shows a third type of support surface 16 suitable
for this method. In this case, support surface 16 is a solid plate
32. A solid plate surface 32 is also shown in FIG. 1 in which a
preform for a part is being formed. Mixture 14 directly adheres to
plate 32 during application. This variation can result in a compact
preform structure 18 as mixture 14 is pressed onto plate 32. Also,
in this case, solidified mixture 14 can have a smooth outer surface
for later treatment.
[0052] Support surface 16 also does not need to be shaped into the
final desired shape of preform 18. Because mixture 14 is applied
while tacky or viscous, by controlling the applied viscosity,
mixture 14 can be pressed into a different desired shape than
support surface 16 before solidification. This allows a large
degree of flexibility in preform shapes as preform 18 is not
restricted to the shape of support surface 16.
[0053] Any suitable materials can be used to create preform 18. The
reinforcing material can be any material suitable as use as
reinforcement. Preferably, the reinforcing material is a relatively
rigid, high aspect ratio material. In a preferred embodiment, the
material is a chopped fibrous material such as fiberglass, aramid
fiber (Kevlar brand fiber), high molecular weight polyolefin such
as ultra high molecular weight polyethylene (UHMWPE), carbon fiber,
arcylonitrile fiber, polyester fiber or a combination of any
thereof. The material can be provided as a chop, or it can be
chopped during or just prior to the application process. It is
preferable that the reinforcement provides a surface with
interstices so that subsequently applied molding material can
closely bind with the reinforcement.
[0054] In the various described embodiments, fibrous reinforcement
cut or chopped sufficiently for deposition via an effector 22 may
be preferred. It should, however, be understood that a continuous
fiber deposition can also or additionally be accomplished in
accordance with the present invention. By appropriate programming
of a robotic arm 20, a suitable end effector 22 can deposit a
continuous fiber on a surface 16 in a pattern (swirls, loops or
other pattern) or orient continuous fiber during deposition in
order to provide certain properties to a preform and to a composite
molded article made from such a preform. For instance, a continuous
fiber pattern can be laid from bow to stem when making a preform
for a boat hull, and/or can be laid transverse across the beam
(port to starboard). The fiber thus laid can be continuous in the
pattern or a chopper can be programmed to cut fiber discretely as
an end effector 22 reaches a designated point as it traverses
across a surface 16. It will also be appreciated that in principle
a chopper, such as a chopper device 44 or a chopper gun in FIGS.
8a-d, can be programmable and thus controlled to permit an end
effector 22 to switch from depositing a mixture of chopped
fiber/binder to depositing continuous fiber (fiber or fiber plus
binder) and so on as a preform is fabricated in a mold.
[0055] The binder can be a commercially available particulate
binder material, including thermoplastic and thermoset polymers,
cellular and non-cellular polymers, glasses, ceramics, metals, or
multi component reactive systems. One type of suitable binder, for
example, is a thermoplastic epoxy hybrid. Preferably, the binder is
a true solid or supercooled liquid at the ambient temperature
prevailing during use so that volatile organics such as solvents
are not present in significant amounts. By this, environmental
problems associated with solvents can be avoided. Further, the
binder is preferably a material that does not need post heat
treatment for curing, thus reducing time and energy requirements.
The particular material can be any known binder, preferably one
that can be conditioned, and/or melted without significant
decomposition, adhered to reinforcing material upon cooling, and
durable at temperature ranges typical in molding. A binder can be
formulated to include a rubbery component or be rubbery binder to
provide toughness to the preform and composite molded article
therefrom. A rubbery component can also be added separately from
the binder and/or separately from fiber. Suitably rubbery
components include, for instance, nitrile, urethane or a
thermoplastic, preferably as suitably sized particulates. Although
a single polymeric binder can be used, a blend is preferred when
the deposited material needs to adhere well on a tall vertical or
tall nearly vertical surface because adhesion is improved,
especially when a curtain of a cooling media is passed over
deposited material (fibers and binder blend). In the various
described embodiments, the binder can advantageously be a mixture
or combination of binders. A commercially available polyester type
binders, such as Stypol.RTM. brand polyesters such as grade
044-8015 (Cook Composites and Polymers), becomes tacky after heat
is applied in a heating zone from burners and can exhibit good
initial adherence to a surface. A hybrid binder, such as a blend of
epoxy and polyester binder ingredients, can become tacky quickly
and, when subjected to a cooling media after being deposited on a
surface, surprisingly can exhibit a comparatively quicker set,
stiffness and rigidity to maintain the fiber in place when a
fiber/binder mixture is applied as deposited material on a vertical
or nearly vertical surface. An exemplary binder blend may
incorporate an epoxy based thermoplastic granular powder (50-100
mesh, <35% fines) having relatively high molecular weight,
softening point approximately 75-80 C, with suitable polyester or
also in combination a lower molecular weight pulverulent epoxy
(50-100 mesh, <35% fines) having a higher softening point
approximately 90 to 95 C, with the latter being more soluble in a
solvent than the former epoxy. Suitable epoxies are available from
Dow Chemical. In principle, suitable combinations of binder
constituents can be chosen based on reactivities, Tg, and the like
known in the powder coating industry. In one of the preferred
embodiments, about 10 wt. % binder relative to glass fibers (cut,
chopped etc.) is used. In a further aspect of one of the preferred
embodiments, the 10 wt. % binder comprises, as a hybrid binder, a
blend of about 3:1 polyester epoxy. The ratio can be adjusted to
suit specific application requirements. The particular binder can
be selected based on the desired characteristics of the preform and
its ultimate intended use. The density of the perform can be
controlled by the length of fiber chop or combination of fiber
lengths applied, the amount of binder and the layer or layer(s) of
fiber/binder applied, and/or by whether or not the perform is
subsequently compressed.
[0056] It will be appreciated that a variation of the described
embodiments in which an end effector 22 deposits what may be termed
a "pre-preg" on a surface 16, which may be a mold surface in mold
tooling, is also part of the invention. In this embodiment, the
amount of fiber reinforcement and resin deposited via an end
effector 22 can include higher quantity of binder(s). For instance,
in a pre-preg type embodiment, the binder(s) can be in an amount
ranging up to approximately 20 to 30 or even up to 40% of the
deposited material on a surface 16. The fiber reinforcement can
constitute approximately the remainder, but is preferably deposited
in higher lofted condition upon deposition for certain end uses.
Higher lofting can be achieved by using longer cut or chopped fiber
lengths, or a higher percentage of longer lengthed fiber
reinforcement.
[0057] In principle, in these and the other embodiments, other
materials can be introduced into an end effector 22 to be applied
to a support surface 16. For example, a preform having potential
electrical conductivity can be prepared by incorporating a powdered
metal, carbon powder, or even an electrically conductive polymer in
the reinforcement stream, the binder stream or by a separate
stream. Flame retardant materials, for example, can be applied when
forming a preform. The additional optional materials can be
incorporated in the mixture as applied to the surface 160f course,
if desired the other materials can be applied separately to a
surface 16 (such as a prepared surface of a mold tool) apart from a
fiber/binder mixture supplied end effector 22.
[0058] An exemplary type of suitable end effector 22 is shown in
FIGS. 3 and 4. End effector 22 is any element that can deliver
material in accordance with the method and its variations disclosed
herein. End effector 22 is preferably carried by robotic arm 20,
but obviously could be manually or otherwise supported. In this
method, a dual heat element configuration is employed. As seen in
FIG. 3, a balanced split supply header 33, preferably natural gas,
feeds two burners 34 and 36. The balanced header 33 splits a main
header to allow common feed to burners 34 and 36 to maintain
uniformity and equity of gas mixture supply and inlet pressure
conditions in-process. Although not shown, an end effector 22
preferably includes a manifold (sometimes referred to as curtain
generating and directing device) capable of providing a curtain of
cooling media, such as air or a non-ignitable gas, to material 14
deposited on a surface 16 as the end effector 22 passes across the
surface 16.
[0059] Each burner 34 and 36 has a burner ignition element 38 and
40, respectively, which could be capable of program driven ignition
or manual remote control. Other burners described herein can be
similarly ignited and controlled. As will be described below, the
dual burner configuration creates a heat envelope or zone 42 within
the flames thrown by burners 34 and 36.
[0060] Preferably, burner(s) 34 (36), for example, provides a
controlled, variable and even temperature profile with a nominal
capacity of about 10,000 BTU per lineal inch of burner. Burner(s)
34 (36) can include a supplied gas mixture control cabinet with
sensors that continually monitor and correct flame mixture quality
and oxygen content. Thus, flame quality can be controlled within
predetermined limits. Automatic shutdown can be provided when the
specified parameters are exceeded or if unsafe mixture conditions
occur. The use of natural gas is preferred for cost and efficiency,
but any fuel could be used. A low pressure flame or, in principle,
a hot air stream, can also be employed. For example, the flame
velocity can be around 1000 feet per minute. Of course, any number
of burners or other suitable heat source(s) could be used depending
on the desired size and configuration of heating zone 42.
[0061] Reinforcing material is provided by material chopping device
44. Chopping device 44 can vary depending on the type of material
being chopped. Chopping device 44 may be fully integrated with the
process control system to allow in-process start, stop, and run
parameter adjustment based on control program requirements or
process sensors and control system signals from process monitoring.
Chopping device 44 may also be manually controlled or varied by
operator input. It is also possible to use pre-chopped material or
other particulate material if desired. A chopping device, such as a
chopping gun, in this or other embodiments herein can provide
chopped fiberous reinforcement in more than one length, i.e. a
quantity of chopped fibrous reinforcement of a certain length and
another quantity of chopped fibrous reinforcement of longer or
shorter length.
[0062] Chopped material 46 is fed through material shape tube 48.
Chopped material 46, also called "chop", can be blown, dropped,
ejected or otherwise expelled from tube 48. Tube 48 is designed to
provide a discrete controlled area for material processing in
preparation for introducing chopped material 46 into the material
stream. It can also provide a controlled volume for any material
conditioning medium that may be desired. As seen in FIG. 3, chopped
material 46 is fed in a stream toward heating zone 42. An air inlet
50 is provided in tube 48 to assist in shaping or orienting the
stream of chopped material 46 as it is expelled from tube 48.
[0063] Binder introduction ports 52 and 54 deposit binder 56, in
the form of streams, toward heat zone 42. Ports 52 and 54 are
preferably designed to introduce air conveyed binder from a metered
dispensing unit into the material stream. Binder 56 can be in the
form of particulate or any conventional form that can be mixed in
with chopped fibers 46, as noted above. In this arrangement, binder
56 is presented as dual streams that are interspersed into the flow
of chopped fibers 46 prior to entering heat zone 42.
[0064] An alternate end effector assembly is shown in FIG. 5, in
which an end effector 60 is mounted on robotic arm 20. In this
arrangement, a central burner element 62 is provided with a single
burner ignition element 64 and a burner face 66. A pair of
reinforcement material chopping devices 68 and 70 are positioned on
either side of burner element 62 and deliver streams of chopped
fiber 46 toward a focal point in heat zone 42 though delivery tubes
72 and 74, respectively. Four binder introduction ports E
(reference numbers 76, 76a, 78, and 78a) are provided adjacent to
reinforcing material delivery tubes 72, 74 to deliver streams of
binder toward the focal point). By this, streams of reinforcing
material 46 and binder 56 can be layered together into the heating
zone 42 to mix the materials and create an adhesive mixture.
Although not shown, an end effector 22 preferably includes a
manifold (sometimes referred to as curtain generating and directing
device) capable of providing a curtain of cooling media, such as
air or a non-ignitable gas, to material 14 deposited on a surface
16 as the end effector 22 is directed or passed across the surface
16.
[0065] Alternatively, binder 56 can be conditioned by a
conditioning device, such as a heater, prior to being introduced
into the stream of reinforcing material 46. In this case, no heat
zone would be necessary, which would eliminate the gas control
cabinet and controls, independent metered binder feed unit, burner
supply header, and the ignition and burner elements. Such a binder
heater could heat treat the material and then blow air across the
surface to eject heated binder particles.
[0066] In operation, the particular end effector could vary
provided that reinforcing material 46 is delivered to a zone in
which heated binder 56 can be mixed therewith. The mixing causes
the materials to adhere into an adhesive mixture 14. Adhesive
mixture 14 is then deposited onto support surface 16 where it
solidifies into preform 18. Use of different end effector
arrangements allows different properties to be achieved. Using
different numbers of streams or layers of reinforcing material 46
and binder 56 will vary the final preform properties. Similarly,
mixing binder 56 after it is heated, before it is heated or while
it is being heated will vary the final properties of preform 18
[0067] As depicted in FIG. 6, another suitable end effector 22
includes venturi 80 that have a generally centrally located port 81
through which reinforcement, chopped fiber glass, carbon fiber or
the like, is introduced. The binder is delivered into a venturi
through port 100, can coat the reinforcement streaming through the
venturi 80 and together with the reinforcement is expelled by a
carrier gas from the venturi 80 through a nozzle 84 in a spray
pattern.
[0068] As shown in FIGS. 6 and 7, opposing burners 85 and 86 are
preferably canted inwardly at a slight angle relative to one
another. In operation, the flames from burners 85 and 86 are
preferably not parallel to a stream of binder and reinforcement
expelled nozzle 84 so that as the stream exits a nozzle, it will
pass through a heating zone created by the flames from burners 85
and 86. This zone is similar to zone 42 (FIG. 3 and FIG. 4). This
is also shown in FIG. 9.
[0069] As described above, an end effector 22 is preferably,
operatively positioned at a distance from a surface 16 (not shown)
in order to achieve a consistent deposit of binder/reinforcement
("deposited material) on the surface.
[0070] With a surface 16 that includes a relatively vertical
portion, vertical portion, or portion having complex curvature or
arc, such as a side of a boat hull or vehicle body part, material
14 (from the stream of binder coated fiber) initially sticks to
such surface. The deposited material 14 can, however, sag, slump or
slough off such vertical portions (sometimes called sections or
regions), such as sections of boat hulls or vehicle parts. A
cooling curtain can overcome the above problem. A gaseous cooling
media, such as an air curtain, from balanced manifolds 88 and 88a
(FIGS. 6, 7, 8 and 9), is applied to the fiber/binder mixture
deposited as an end effector 22 traverses over a surface 16 or over
a previously deposited layer on a surface. The cooling provided is
such that the binder may be induced to more quickly set, or at
least more completely partially cure, so the deposited material can
retain internal rigidity, shape and position on a vertical portion,
nearly vertical portion, or a highly complex curved portion of a
surface 16. Steeply sloped portions of a surface 16 also
advantageously receive deposited material with subsequent cooling
from a cooling curtain as described above. As shown in FIGS. 6 and
7, manifolds 88 and 88a can include a guide element 89 to help
direct the cooling media to the surface 16 while minimizing
potential interference with the heating zone established by the
flames from burners 85 and 86. The guide element 89 also helps
avoid accumulation of fibers and stray binder from accumulating on
and potentially clogging the manifolds 88 and 88a. The manifolds,
e.g., cooling curtain generating and delivering devices, provide a
gaseous cooling media that can, if desired, be pre-cooled or
conditioned. The gaseous cooling media can be air or an inert,
non-ignitable gas such as nitrogen. An air curtain can also
advantageously entrain surrounding atmosphere as it flows towards a
surface 16 to thereby increase the overall volume of cooling media
applied. The cooling media supplied via manifolds 88 and 88a is
preferably subject to process controls that regulate, for instance,
the rate, amount, pressure, duration, and interruption in the
supply or application of the cooling media.
[0071] As shown in FIG. 7A, venturi 80 can include a port 100 for
introducing binder, a fiber port 81 (sometimes referred to herein
as an inlet) for introducing fiber (cut fiber glass, carbon fiber,
polyester fiber, acrylonitrile fiber, aramid fiber (Kevlar brand
fiber), and/or HMWPE, chopped or cut to a desired length(s)), a
port 102 for introducing a pressurized carrier gas, and nozzle 84.
By present preference, in operation, the binder is delivered
through a binder inlet 100, preferably into approximately the
center of a fiber stream before the constriction in the central
passage way of venturi 80. Due to the venturi effect, venturi 80
can pull the fiber reinforcement from a fiber source, such as
chopper gun operatively connected to venturi 80, the fiber and
binder are admixed in venturi 80, and then propelled (expelled)
from venturi 80 through nozzle 84 by the carrier gas. The expelled
material passes through a heating zone to be heated on its way
towards the target surface, which can be a prepared surface of a
mold tool. In this embodiment, a heating zone can be formed
downstream of the fan nozzles 84 about a region where flame from
the burners 85 and 86 is thrown. The adhesive mixture of
fibers/binder passes through the heating zone (FIG. 9). Presently,
a separate carrier gas stream is preferably used and is introduced
through port 102. However, variations in venturi design and
operation are within the scope of the invention. For instance, the
binder can also be introduced into venturi 80 through port 102 with
forced carrier media, such as ambient air or other suitable gas,
and this carrier media can, if desired, be used as a carrier gas
for venturi 80. The fibers can also be pulled or expelled from a
chopper gun or fiber source by a carrier media, such as an air
stream, into the fiber port 81. In either case, the carrier gas,
its rate of flow, and the like are preferably subject to
appropriate process controls, such as computer controls, including
flow regulators. An end effector 22 can have one or more venturi 80
or another configuration of venturi 80. A venturi 80 is an
effective and efficient means for delivering an adhesive
combination of fiber with binder through a heating zone before
being deposited on a surface 16.
[0072] The rate of media flow through venturi 80 out nozzles 84 is
a parameter affecting the dwell time of the fiber/binder mixture
(sometimes called mixture 14) in the heating zone 42 and thus the
qualities of the perform. Accordingly, the velocity of gas flow
through venturi 80 can be monitored and controlled by suitable
process controls when the end effector 22 is in operation. Or, for
instance, the flow rates can be manually set, in which case the
flow rate will be measured and dwell time ascertained based on the
flow rate through the heating zone. Thus, if a binder is introduced
into venturi 80 with a binder carrier gas, the binder supply can be
shut off and binder carrier gas allowed to flow through venturi 80.
Similarly, if fibrous reinforcement, or any other material, is
propelled into a venturi 80 with a gas, the fiber and all other
material supply can be shut off and its carrier gas allowed to flow
through venturi 80. The velocity of all "carrier gas" through the
venturi 80 can be monitored and measured from which a dwell time in
the heat zone can be calculated or estimated and the flow rate(s)
set manually or adjusted by process controls. The dwell time in
heating zone 42 establishes a thermal treatment suitable for the
binder(s) in the fiber/binder mixture so that when deposited on the
surface 16, such as a mold tool, the fiber/binder mixture is at
least more capable of retaining its shape and position without
undesired sagging, slumping and the like. Inadequate dwell time can
lead to poorly adherent deposited materials and thus an inferior
preform. It will be appreciated that the parameters may, in
principle, also be ascertained for a particular process combination
by conducting appropriate test runs.
[0073] In FIGS. 8a-8d show an end effector of FIG. 6 in which guide
elements 89 are not installed with a chopped gun assembly. FIGS. 8a
and 8b depict end effector 22 in operative connection with a
chopper gun and FIGS. 8c and 8d depict end effector 22 and a
chopper gun separated to show how they may be connected.
[0074] In FIG. 9 an end effector 22 on a robotic arm 20 is shown in
which a stream of material propelled through nozzle 84 passes
through a heating zone established by the flames from burners 85
and 86. The stream of reinforcement and binder propelled from a fan
nozzle 84 passes through or by a heating zone established by the
flame from the burners before being deposited on a surface 16 (not
shown).
[0075] End effector 22 on a robotic arm 20 can be controlled as
shown in FIG. 10 to apply (spray deposit etc.) fiber/binder in a
pre-selected pattern. More particularly, FIG. 10 shows a robot arm
20 with an end effector 22 being applied in a controlled pattern to
form a preform in a first mold. The arrows depict an exemplary
pattern of deposited material corresponding to the pre-selected
traverse of end effector 22 over the surface. The robot arm is
preferably under process controls, such as computer programming or
the like.
[0076] FIG. 11 illustrates a computer controlled robotic arm 20, an
end effector 22 (with air curtains), the flange 92 of a first mold
tool 90, a skirt 91 about the exterior of the first mold tool 90.
In this embodiment, the first mold tool 90 can have a gel coat on
the molding surface and, optionally barrier coat(s) and/or
reinforcement layer(s) laid over the gel coat, before the
fiber/binder is sprayed to form the boat bull preform 95 as
shown.
[0077] FIG. 12 and FIG. 13 show, respectively, a preform 95
obtained after completing the fiber/binder application with slight
over spray of material (FIG. 12) protruding over the flange 92 (not
seen), and the trimmed preform 95a in the first mold tool 90 (FIG.
13) with the flange 92 clear. In FIG. 13, the protective skirt 91
has been removed to show a portion of support structure 96 for
first mold tool 90.
[0078] FIG. 14 shows a trimmed preform 95a in a first mold tool 90
having support structure 96 and in open relationship to matching
second mold tool 90a. The second mold tool 90a can be closed, e.g.
clamped or be vacuum sealed, in operative molding relationship with
first mold tool 90 to define a mold cavity containing preform 95a
and resin can be introduced into the cavity of the closed mold. A
gantry or frame 99 with a lift capability is shown supporting mold
tool 90a in open, opposed relationship to mold tool 90. Gantry or
frame 99 can lower mold tool 90a to mold tool 90 to establish a
closed mold. It will be appreciated that the gantry or frame may
have extendible and retractable (or even rotatable) armature
support for mold tool 90a to more readily permit, among other
things, its spatial adjustment over a mold tool 90 prior to forming
the closed mold tool. Mold tool 90 with a formed-in-place preform
95a (a boat hull) has been moved between work stations. Support
structure 96 can include or be operatively connectable to a
transport system 98 so that after preform 95a is prepared in a work
station, it can be transported while remaining in the mold tool 90
within the factory to another work station and positioned in
operative relationship to receive other treatment, such as in this
case being positioned relative to mold tool 90a. Transport system
98 includes rails as shown. It will be appreciated that other
suitable apparatus for shifting work pieces (mold tools etc.)
between different work stations in factory can be employed as shown
in FIG. 15. For smaller work pieces a manually movable apparatus
for conveying a mold tool with preform from one to another work
station. It is in principle possible to have the gantry or frame 99
also on tracks or connected to other suitable transport mechanism
to permit movement within a factory. It will be appreciated that
the transport system or mechanism may also be process
controlled.
[0079] FIG. 15 shows the surface 16 of a first mold tool 90 (not
shown) and a pair robotic controlled arms 20 and 20a, end effector
22, and a carriage (roller as illustrated). Each end effector 22
can deposit the same or a different fiber/binder mixture. By
preference, each is also process controlled. Robotic arms 20 and
20a can each more readily extend their respective end effector 22
across a surface 16, such as a mold tool 90, to a far side away
from their respective base 20b and 20c to more readily permit even
deposition of fiber/binder to a respective opposing portion of
surface 16, such as a mold tool 90, especially if such opposing
portion has a complex shape or steep portion.
[0080] As will be understood, preform 18 or 95a can be used to
fabricate a composite molded article in subsequent processing using
resin transfer molding (RTM), VARTM (vacuum assist resin transfer
molding), compression molding process, structural-reaction
injection molding (S-RIM), or, for instance, in a vacuum infusion
process. Heat and/or pressure molding steps can be employed in
fabricating a composite article from a preform.
[0081] Of course, any suitable end effector 22 can be used,
provided that the appropriate mixing and heat control can be
employed. As can be understood from above, preform 18 or 95a can be
made with different properties by controlling, for instance, the
heating zone, the temperature of the binder, reinforcement and the
degree to which reinforcement fiber is chopped or cut, and the
distance between end effector 22 and support surface 16. For
example, the material 14 or a fiber/binder mixture as in FIG. 9 can
be controlled so that the mixture has sufficient tackiness when
applied to support surface 16 so that it quickly solidifies.
Alternatively, mixing can be controlled so that the mixture applied
(hitting) support surface 16 is sufficiently tacky to adhere to
support surface 16 but remain moldable so that it can be pressed or
further shaped.
[0082] As described herein, control of the various elements and
parameters can be manual or automated. If automated, a system can
be provided using known programming techniques in a controller or
processing apparatus, such as a microprocessor. Process control,
especially robotic control, can be achieved by robot control
signals, process sensor feedback signals, process material
regulation, material selection and preset specifications. These and
other concepts are also embodied within the term computer
controlled, or the like. Programming packages are commercially
available that can be used to program a controller for a robotic
arm 20 or chopper gun. Using process control for a robotic arm
helps ensure correct orientation of end effector 22, attaining an
optimal concentration of fiber over surface 16 or other surface to
which the material is deposited with minimal deviations and minimal
variation between like-made preforms.
[0083] Although mentioned elsewhere, the parameters that affect
preform fabrication include the level of control of the heat source
or flame, the velocity at which the flame, binder and chop are
introduced, the ratio between these elements, and the distance of
end effector 22 from a support surface 16, which can be a prepared
surface of a mold tool 90 or 90a as the case may be. For example,
if a less viscous mixture is desired, a binder can be selected that
is less viscous when heated to a higher temperature. By this
method, application of adhesive mixture can be controlled. Adhesive
mixture also does not need to be applied at a high velocity and
pressure. Because an adhesive mixture, such as a mixture 14,
adheres to support surface 16, it may be draped over a surface 16
(or mold tool 90) to achieve different qualities in a preform 18 or
preform 95a.
[0084] As mixture 14 can stick to support surface 16 due, for
instance, to the conditioning during the mixing operation, no
additional methods of holding the reinforcing material 46 in place
are necessarily required. This eliminates the need for any vacuum
or plenum assembly over the mold. Further, since a low pressure
flame velocity is used, the problem of blowing reinforcing material
off of support surface 16 or to different places on support surface
16 is not present. Additionally, since mixture 14 can be closely
controlled, different shapes and thickness of preform 18 can be
achieved. However, as described herein, the adhesive mixture
advantageously receives cooling from a gaseous cooling curtain,
especially if the surface 16 is or has a tall vertical or near
vertical section, such as the freeboard of a large boat hull.
[0085] Thus, it can be seen that the apparatus, the method and
their variations in accordance with this invention allows
complicated shapes to be easily molded directly on a forming
surface, such as a mold tool, thus simplifying the process of
making preform 18 or 95 a and also the ultimate molding processes
in which preform 18 or 95a is used. Also, a one piece preform, even
in large shapes such as boat hulls, can be formed using the preform
without first removing the preform from its mold tooling. This
reduces labor costs and production time and can result in a
stronger composite part.
[0086] Preform 18 or 95a formed in accordance with any of the above
embodiments can be used in a molding process to make a composite
structural part. For example, preform 18 or 95a may be used in a
vacuum molding process in which resin is applied to preform 18 or
95a with the assistance of vacuum and then the composite structure
is cured. Alternatively, a molding material, such as resin, can be
applied to preform 18 or 95a and, then, heat and/or pressure can be
applied to form the composite part. Also, simply heat and/or
pressure can be applied to preform 18 or 95a to compress mixture 14
and form a part. The pressure can include reduced pressure in a
vacuum bagging apparatus. The direct formation of a composite is
particularly suited for the pre-preg embodiment. Pre-preg
embodiment may find particular application in aerospace and
non-civilian applications.
[0087] The present invention offers a composite part maker a cost
advantageous process to apply fiber reinforcement directly into
existing gel-coated mold tool to fabricate a preform without having
to remove the preform from its associated mold tooling in order to
make the final composite molded article. It will be appreciated
that the preform can have a shaped surface corresponding to a
desired shaped surface of the finished composite molded
article.
[0088] For example, a preform made according to this invention
could be used in a molding process that includes the following
steps. After the preform is solidified, the preform remains in its
mold (or, is placed in a suitable mold) and a molding material,
such as resin, is applied. A gel coat or the like can, if desired,
be formed first in the mold before a preform is placed in the mold.
The mold can be an open mold or a closed mold. In the latter case,
the molding tool would usually be closed prior to introduction of
resin into the mold cavity. Then, after the mold is completely
filled, the resin is cured. The article can then be removed from
the mold and used in that state or further treated or shaped to
suit a manufacturing process. Before the introduction of the
molding material, the preform could also be shaped prior to its
complete solidification, cut, or heated and shaped to conform to
desired molding conditions. Additionally, separate preforms could
be used together to form a structural base prior to molding.
[0089] More particularly, in a manufacturing embodiment, a boat
hull, boat deck or other composite part can be prepared as follows.
A first molding tool is prepared. Preparing the mold surface of the
first mold tool can include cleaning and, as necessary, providing a
coating of a release agent. The prepared mold tool can be gel
coated. For instance, if a surface of a finished composite part
formed by the first mold surface needs to have a decorative or
protective coating, a so-called powder coating can be applied to
the molding surface of the prepared first mold. Or, such surface it
can, if desired, be only primed. A gel coating or powder coating
may be omitted if no specific surface coating is required on either
a preform or final composite. If a gel-coat is applied, it is
preferably allowed to cure. Barrier coats, as needed or desired,
can be applied over the gel-coat. If the first mold tool has a
section, area or region having a tight radius or complex
curvatures, fiber strands or air fluffed fiber strands, or strips
of any other reinforcement can be laid up, if desired, over any
coating (gel coat or barrier layer(s)) in the tight radius or on
the complex curvature to minimize fiber bridging during later
process steps. Shorter length fibers can also be applied with an
end effector 22 into these tight corners or complex curvatures to
minimize fiber bridging. The first mold tool and its support (if
support is provided) are positioned and fiber/binder are applied
directly to form a mat of deposited material onto the cured
gel-coat preferably using at least one robotically controlled
device equipped with an end effector 22. The robotically controlled
device is preferably operatively equipped with an end effector 22
having venturi 80 and cooling curtain means 88 and/or 88a. The
fiber/binder mixture, such as in FIG. 9 or mixture 14, can be
applied according to a selected pattern, such as shown in FIG. 10,
as deposited material and can be applied to form layer(s) in a mat
of fiber/binder. The mat preferably has open interstices between
and among fibers. Robotically applied material is preferably
computer controlled to assure ready, repeatable fabrication of a
particular preform design. For instance, fiber chop, binder feed,
spray patterns, layering, flame temperature, cooling air (cooling
curtain), and distance from the substrate are among the features
that can be computer controlled. It will be appreciated, however,
that the fiber/binder can be applied by manually controlling an end
effector 22, but this could introduce process variation and cause
reduced consistency in both the process and in the finished
composite structure. It will also be appreciated that different
fiber materials can be applied by end effector 22 or a plurality of
end effectors 22 in order to form differing layers or regions of a
preform with different composite properties. For example, in a
multi-layered preform, different layers can in principle have
different fiber reinforcement or different fiber orientation(s). A
carbon fiber layer can be applied on top of the e-glass layer to
replace in whole or in part an engineered fabric that may otherwise
be laid into the mold tool during the process of fabricating a
preform. Of course, application of carbon fiber alone, another
fiber(s) alone, e-glass (fiber glass etc.) alone or any in
combination is contemplated by our invention. Depending on the
composite structure to be produced, other engineered fabrics can be
laid in as desired before, during, or after the fiber/binder are
applied. It will be appreciated that in manufacturing certain boat
hulls or other marine composites, additional structural elements,
such as stingers, bulkheads, flooring support, and the like, can be
introduced into the first mold as the preform is being formed or
afterwards. Such additional structural elements can be used to
define storage areas or, for instance, compartments in which a
marine motor or fuel tank can be installed. Stringers, bulkheads,
other structural elements and the like, such as disclosed in U.S.
Pat. No. 5,664,518, the complete disclosure of which is
incorporated herein by reference, can be used. Obviously, the
preform fabrication method could be adapted to fabricate
pre-glassed structural elements themselves. Closed cell shaped foam
or other structural material can be laid in to provide additional
preform structure, such as a bulkhead, stringer etc., even without
being pre-glassed or pre-fleeced with fiber-reinforcement,
preferably before the fiber/resin completely cures. The foam or
other structural material can have a surface(s) prepared with
adhesive or binder compatible with the deposited material in a
preform. The fiber/binder application can be interrupted to permit
installation of additional structural element(s), in which case the
fiber/binder application can be resumed, as desired, to provide a
layer(s) deposited over the added structural element(s) to make it
an integral and relatively seamless part of the preform. After a
material is deposited on the surface, especially if the surface has
a steeply sloped or a tall vertical section, an end effector 22
(FIGS. 6 and 7) having manifolds 88 and/or 88a (e.g., at least one
cooling curtain means) applies a curtain of gaseous cooling media
to the just deposited material to avoid sagging, slumping,
sloughing off or other separation of the deposited fiber/binder
from the surface or from another intervening layer deposited on the
surface. After the fiber/binder application is completed and cures,
the preform obtained is trimmed as needed and the flange of a first
mold tool etc. is cleaned as necessary. In a preferred embodiment,
a closed mold system is used with the first mold tool being a
female mold and a second mold tool being a matching male mold
wherein one or both of the first and second molds is closable with
respect to the other so as to define there between a mold cavity.
Depending on the molding process, in a subsequent step resin can be
injected or infused into the mold cavity. In manufacturing a boat,
any conventional resin can be used, including thermoplastic resin.
The resin cures, the mold is opened and the thus produced composite
(boat hull in this example) is removed.
[0090] It will also be appreciated that a composite structure, such
as a boat hull, can be prepared with a finished exterior exposed
hull surface and a finished interior (deck, cockpit etc.) exposed
surface. In this embodiment, the general procedure can be the same
as above but modified so that the molding surface of the second
mold is coated with release agent, gel-coated or finish coated
before it is closed with the first mold tool and the resin is
introduced into the cavity defined by the closed mold tools. The
second mold can be contoured so that the finished composite can
have the desired interior surface. In principle, the general
procedure can be modified further to fabricate a composite formed
from a preform in the first mold and a preform fabricated in the
second mold. When the matching first and second molds are closed,
the injected or infused resin bonds the two preforms together. In
this and other embodiments, the resin can, in principle, be
foamable for use in a closed or open mold application.
[0091] The use of an end effector 22 in accordance with the present
invention can be combined with so-called zero injection pressure
resin transfer molding ("ZIP RTM molding"). The latter molding
process is generally described in Composite Fabrication, pages
24-28 (March 2003), the complete disclosure of which is
incorporated herein by reference. For instance, an end effector 22,
preferably one with curtain(s) of cooling media and using a venturi
for fiber and binder supply, can be used to form a layer(s) of
fiber/binder instead of hand laying in the fiber mats and binder.
Although vacuum can be applied to frames in a ZIP RTM molding
process, it is not a requirement in the present embodiment. For
instance, a lower molding tool according to a ZIP RTM molding
process can be used as a first mold in this embodiment because it
is similar to an open mold, but advantageously lighter mold tooling
becomes feasible.
[0092] It will be appreciated that a composite structure can be
prepared in which instead of a gel coating, a skin layer can be
first formed in a first mold and, optionally, one or more barrier
layers (solid and/or foamed) can be formed on the exposed surface
of the skin layer, and fiber/binder layer(s) can be applied over
the barrier layer(s) using an end effector 22 in accordance with
the present invention. The remainder of the procedure can be
conducted as described above. In a further variation of this and
the other embodiments, all or part of the resin introduced into the
closed mold can be a foamable resin.
[0093] It will be appreciated that manifold 88 and/or 88a can be
selectively controlled so as to supply a warmer or hot air curtain,
if needed, or one can supply a warm or hot air curtain and the
other a cooling air curtain. In this variation, each manifold can
be appropriately process controlled so that an air curtain of a
selected temperature can be applied.
[0094] Various parts can be made, as noted above, that are useable
in the marine industry or other industries that utilize fiberglass
reinforced articles. For example, partial hulls, boat decks in
whole or part, hatches, covers, engine covers, marine accessories
and the like may be manufactured using preforms made in accordance
with this process. Similarly, other marine vessels such as personal
watercraft may be manufactured with parts made from this process,
including for example, engine covers, hulls in whole or part,
hatches and the like. Parts made according to this process would
also be usable in the automotive industry to manufacture both
interior and exterior components or body parts for vehicles. The
use of such parts is not limited to vehicles as such parts could be
used in any structural article, such as a storage container or
construction component.
[0095] The complete disclosure of U.S. application Ser. No.
10/038,771, filed Jan. 8, 2002 is incorporated herein by
reference.
[0096] It is to be understood that the essence of the present
invention is not confined to the particular embodiments described
herein but extends to other embodiments and modifications that can
be encompassed by the appended claims.
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