Note: Descriptions are shown in the official language in which they were submitted.
. ..._ ...... .. ... .. . ....I... .. ,..., . , .. ...,......-.-.---_....
.. . - .. ..:.... :............... .............: ., .,......-.....
CA 02617076 2007-12-21
1
COMPOSITE AND METAL COMPONENT PRODUCTION. FORMING AND
BONDING SYSTEM
The present invention is directed to the manufacture of composite as well
as super plastic forming and bonding of thin sheet metal components.
Composite components are typically produced by impregnating a fibrous
material such as fiberglass with a resin matrix or bonding medium such as
thermoplastic or thermocuring resin, or forming and bonding sheets of
thermoplastic material together or in layers to fonn parts. This resin
impregnated
material is subsequently subjected to an elevated pressure and temperature to
compress the material and form or cure the resin matrix or bonding medium to
thereby produce the composite/bonded component. Bonded metal components
are formed by shaping the thin metal sheets and placing adhesive or bonding
material between the sheets then elevating the temperature whilst maintaining
a
holding pressure or clamping force to ensure an adequate bond. In each case
the material needs to be compressed to expel excess air and resin from within
the
composite lay-up or metal bond to cure the laminate into a solid layer or bond
the
solid laminates together to form a final part. Lightweight components of high
strength can be produced by this method making such components particularly
suitable for aircraft, automotive and marine applications.
The Applicant has developed a system for praducing such composite
components as described in U.S. Patent No. 6,149,844. The described system
uses a pair of pressure chambers respectively providing a mould surface and a
backing surface. The mould surface may be provided by a floating rigid or semi
rigid mould forming a wall of one of the pressure chambers. The backing
surface
may be provided by either a second cooperating floating rigid or semi rigid
mould,
or a vacuum bag, or a resiliently deformable bladder forming a wail of the
other
pressure chamber. A composite lay-up may be made up of a layer of resin
impregnated material overlaid by a peel cloth and a bleeder cloth which can be
located between the mould and backing surfaces. Once the composite lay-up are
placed in position, fluid at elevated pressure and temperature is circulated
through each pressure chamber to thereby both compress the lay-up and form or
cure the resin matrix or bonding medium. Altematively, layers of material may
be
initially laid in the mould to provide a laminate, and Resin Transfer Moulding
or
_ _ ... _ . ..,._ ......_..._------- -
CA 02617076 2007-12-21
2
Resin Film Infusion used to introduce the resin to the laminate thereby
allowing
forming of the part. The circulation of the fluid provides for very uniform
curing of
the component with fast cycle times, heat up and cool down and efficient
energy
use. Furthermore, in a preferred arrangement of this system, equal pressures
can be applied to opposing sides of the composite lay-up because fluid at the
same pressure is circulated through each pressure chamber. The resultant
composite component has excellent material uniformity when compared with
composite components manufactured with other known composite production
processes.
The Applicant has also developed a system for producing, repairing,
forming, and bonding both composite and metal components in Canadian
Application No. 2,401,811 using at least one pressure chamber having a
displaceable abutment face, with fluid being circulated at an elevated
temperature
and pressure.
In all of the systems, developed by the Applicant, the common principle of
operation is the use of circulating fluid at elevated temperature and pressure
to
effect the curing process. The advantage of using circulating fluid as a
heating
(or cooling medium) is the ability to transfer heat rapidly and evenly to the
area
being heating. In practice, this resuits in curing times for the production
composite products that are substantially shorter than that possible with
conventional autoclave production processes. This is because of the higher
heat
transfer rates in fluid compared with air (le typically 22 times greater with
water).
The result Is substantially greater production speeds and lower overall
production
costs per unit.
Another advantage in using circulating fluid is that the heat is transferred
more evenly to the lay-up with no "hot spots" as can occur using autoclave or
other heating methods.
The Applicant's systems also provide relatively uniform pressure over the
lay-up because of their use of circulating fluid at elevated pressure.
Furthermore,
in the arrangements where pressure is applied to opposing sides of a lay-up,
the
pressure can be balanced such that it Is unnecessary to use apparatus having
high structural strength to support any applied heavy loads.
............... .~_
CA 02617076 2007-12-21
3
Furthermore, the present invention can utilize a "balanced density" effect
wliich enables large panels and components to be produced. Details of this
effect will be hereinafter further described.
While the composite component production system described in U.S.
Patent No. 6,149,844 is in use, it is not possible to prepare the next
composite
lay-up until the composite component currently being manufactured has been
cured or formed. Furthermore, it is not possible to readily change moulds to
produce a different composite component as this requires the floating rigid or
semi rigid mould to be detached from the pressure chamber and to be replaced
with another rigid or semi rigid mould of a different configuration.
With the mould fixed in the wall of the pressure chamber it Is difficult to
maneuver
the mould to get access to the mould for example to place the -composite
materials into the mould.
In addition it is difficult to work on the mould to place the stiffeners into
the
part whilst it is in the pressure cell with the pressure chambers surrounding
it. It is
possible to take the composite part out of the mould then place it 9n a jig
and fit
the stiffeners e.g. ribs, bulkheads, strongbacks etc. However this is not
preferable as the composite component is not generally rigid and tends to flex
until all stiffeners are in position. It is therefore preferable to place all
stiffeners
and complete all secondary processes before removing the part from the mould.
In this way maximum dimensional accuracy is ensured:
Also in some circumstances it is necessary or preferable to have split
moulds to release a part from the mould. This is difficult to accommodate
within
the present process without split pressure chambers and sophisticated locking
mechanisms in the walls of the mould to hold the moulds together to ensure no
loss of fluids.
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
4
Also, it is difficult to adapt the pressure chamber to produce composite
components of widely different sizes because of the floating mould
arrangement.
This is therefore a"batch" process where it is not possible to undertake any
further action until the current curing, forming procedure is completed. It
would
however be advantageous to be able to have a composite production system that
allows for a "semi-continuous" process where at least a part of the
manufacturing
procedure can be done even when the system is currently compacting, curing
and or forming a composite or bonded metal component while at the same time
maintaining the quality of the component produced by such a system. It would
also be advantageous to be able to produce a variety of different components
and
moulds for those components themselves radically decreasing the cost of
tooling
without having to alter the basic configuration of the sealed pressure
chambers
and the release of fluid from the system. This will facilitate the
introduction of
such a system to mass production applications because of the improved time and
production efficiency.
It is therefore an object of the present invention to provide an improved
system and method for producing composite or bonded metal components.
With this in mind, according to one aspect of the present invention, there is
provided a system for producing composite or bonded metal components
including:
first and second pressure chambers, each pressure chamber having an
elastically
deformable chamber wall;
means for circulating fluid at an elevated temperature and pressure through
each
said pressure chamber; and
at least one mould assembly including at least one separate mould section
providing a mould cavity within which a composite or bonded metal lay-up can
be
located;
wherein when the system is in use, the pressure chambers are held together
with
the elastically deformable chamber walls located in opposing relation, the at
least
one mould assembly containing a said lay-up being accommodated between the
chamber walls while fluid at elevated temperature and pressure is circulated
CA 02617076 2007-12-21
WO 02/058916 PCT/A1J02/00078
through each pressure chamber such that the lay-up can be compressed and
cured or formed.
The fiuid circulated through each pressure chamber may be maintained at
substantially the same pressure such that the forces acting around the mould
5 assembly and lay-up are balanced. This facilitates the use of chamber walls
of
an elastically deformable material such as that do not need to be of
substantial
mechanical strength to maintain dimensional accuracy and can therefore be of
lighter construction. The chamber walls can therefore be relatively thin to
allow
heat to be readily transferred through to the mould assembly and lay-up.
The elastically deformable chamber walls also conform closely about the
shape of the mould assembly and supported lay-up ensuring relatively uniform
heat transfer throughout the mould assembly.
In certain components having a particularly convoluted outer shape, the
chamber wall overlying the lay-up may not be able to properly conform against
the outer shape. This could for example occur where the component to be
produced has deep cavities or channels therein.
Under these circumstances, the chamber wall overlying the lay-up may be
configured to at least generally conform with the shape of the component being
produced. The circulation of fluid through the pressure chamber supporting the
configured chamber wall would urge that configured wall chamber wall closely
to
the shape of the component.
Because the mould assembly is separate from the pressure chambers, it
facilitates the use of the system according to the present invention is a semi-
continuous process because the mould assembly and lay-up can be assembled
separately from the pressure chambers. Furthermore, further mould assemblies
may be set up while the pressure chambers are being used
According to another aspect of the present invention, there is provided a
method of producing composite or bonded metal components including:
locating a composite or bonded metal lay-up in a mould cavity of a mould
assembly;
locating the mould- assembly together with the lay-up between first and second
pressure chambers, each pressure chamber having an elastically deformable
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
6
locating the mould assembly together with the lay-up between first and second
pressure chambers, each pressure chamber having an elastically deformable
chamber wall, the chamber walls being located in opposing relation with the
mould assembly located therebetween; and
circulating a fluid at an elevated pressure and temperature though each
pressure =
chamber such that the composite or bonded metal lay-up is compressed and
cured or formed.
The mould assembly may include a single mould section for supporting the
composite or bonded metal lay-up, with one of the elastically deformable walls
being in direct contact with the composite or bonded metal lay-up or a bleeder
cloth located over the lay-up when located between the two pressure chambers.
The mould section may be of a rigid or semi rigid construction. It is also
envisaged that the mould assembly include a pair of cooperating rigid or semi
rigid mould sections such that the composite or bonded metal lay-up can be
located therebetween.
The mould section(s) may be split to facilitate release of the completed
component therefrom. This is feasible in the system according to the present
invention because the mould section(s) being separate from the pressure
chambers can be easily split when separate from and outside the pressure
chambers. In this way the pressure chambers remain untouched and completely
sealed at all times. Therefore the ability to remove the mould section(s)
containing the part from the pressure chambers is preferable to having the
mould
section(s) sealed and attached to the pressure chamber.
Where a single mould section is used, a vacuum bag may be used to
provide an initial compression of the lay-up. To this end, the vacuum bag may
be
located over the lay-up, and the lay-up compressed prior to the mould assembly
being compressed between the pressure chambers.
The pressure chamber may include a housing supporting a said elastically
deformable chamber wall on a side thereof. The said wall may have pockets,
rings or attachment points for the moulds either in the elastic wall or to the
walls
of the respective pressure chambers or pockets cut in a rigid wali and lined
with
CA 02617076 2007112-21
WO 02/058916 PCT/AU02/00078
7
elastic material to suit the mould. The chamber wall may be formed of an
elastically deformable material such as rubber.
Alternatively, the pressure chamber may include an outer support housing
or frame supporting a flexible bladder therein. One face of the bladder may
provide the elastically deformable chamber wall for the pressure chamber. This
arrangement facilitates the maintenance of the pressure chambers. For example,
if any leak is found in the pressure bladder, that bladder can be simply
removed
and replaced with another bladder. There is also no need to provide any
specially sealing arrangement between the housing and a separate elastically
deformable wall which would be susceptible to leaks.
As the heat is transferred through the chamber walls, they need to conform
very closely to the shape of the mould assembly to ensure that there is
relatively
uniform heat transfer around the outer surface of the mould assembly and the
lay-
up located therein. This can however be difficult to achieve where the shape
of
the mould assembly is particularly convoluted. For example, mould assemblies
having deep channels extending therealong can make it difficult for the
chamber
walls to conform around the mould assembly and the lay-up located therein.
Therefore, according to another aspect of the present invention, there is
provided a mould assembly for a system for producing composite bonding metal
components including:
a mould section having opposing faces;
one of said mould section faces providing a mould cavity;
the mould assembly further including a fluid flow chamber provided adjacent
the
opposing mould section face such that fluid circulated through the fluid flow
chamber is in direct contact with at least a substantial portion of the
opposing
mould section face.
The fluid flow chamber may include a bladder formed of elastically
deformable material such as silicon rubber secured to the mould section along
its
periphery thereby covering at least a substantial portion of the adjacent
mould
section face. At least one support membrane may interconnect the bladder and
the mould section face to provide further support to the bladder as well as to
guide the fluid flow through the fluid flow chamber. It is also envisaged that
at
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
8
least one rigid or semi-rigid heat transfer fin may extend from the mould
section
face. The fin(s) may facilitate the heat transfer to the mould section and
help
guide the fluid flow. Furthermore, the fin(s) may be attached to the bladder
to
provide further support for the bladder.
It is alternatively envisaged that, the fluid flow chamber may be provided
by a rigid or semi-rigid housing or plate resiliently secured along its
periphery to
the mould section face through which fluid may be circulated.
The provision of the fluid flow chamber provides direct contact of fluid to a
substantial portion of the mould section face maximizing heat transfer from
the
fluid to the mould face. The above described mould assembly can be used in the
production system according to the present invention.
Therefore, according to a further aspect of the present invention, there Is
provided a system for producing composite or bonded metal components
including:
first and second pressure chambers, each pressure chamber having an
elastically
deformable chamber wall;
at least one mould assembly including a mould section having opposing faces;
one of said mould section face providing a mould cavity within which a
composite
or bonded metal lay-up can be located; the at least one mould assembly
including
a fluid flow chamber provided adjacent a said mould section face such that
fluid
circulated through the fluid flow chamber is in direct contact with at ieast a
substantial portion of the opposing mould section face; and
means for circulating fluid at an elevated temperature and pressure through
each
said pressure chamber and through the fluid flow chamber;
wherein when the system is in use, the pressure chambers are held together
with
the elastically deformable chamber walls located in opposing relation, the at
least
one mould assembly containing a said lay-up being accommodated between the
chamber walls while fluid at elevated temperature and pr-essure is circulated
through each pressure chamber and the fluid flow chamber of the at least one
mould assembly such that the lay-up can be compressed and cured or formed.
According to yet another aspect of the present invention, there is provided
a method of producing composite or bonded metal components including:
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
9
locating a composite or bonded metal lay-up in a mould cavity of a mould
assembly including a mould section, the mould section including a face
opposing
the mould cavity, with a fluid flow chamber being located adjacent said
opposing
mould section face;
locating the mould section together with the lay-up between the first and
second
pressure chambers, each pressure chamber having an elastically deformable
chamber wall, the chamber walls being located in opposing relations with the
mould sections with said lay-up located therebetween; and
circulating fluid at an elevated temperature and pressure through each
pressure
cMamber and the fluid flow chamber such that the composite or bonded metal lay-
up is compressed and cured or formed.
The use of the mould assembly with the fluid flow chamber having fluid
circulating therethrough allows a separation of the components providing the
pressure application (the pressure chambers) and the component providing the
heat application (the mould asserribly). The facilitates improved management
of
both the pressure and heat application to the mould assembly.
As fluid is separately circulated through the pressure chambers and the
fluid flow chamber, the temperature of the circulating fluid in the pressure
chambers can be maintained relatively constant (for example, about 80 C) while
the temperature of the fluid circulating through the fluid flow chamber can be
cycled between higher and lower temperatures (for example between 40 - 200 C).
This is because it is not necessary in this arrangement to heat or cool the
pressure chamber walls. It is therefore that fluid passing through the fluid
flow
chamber that provides the principal heat or cooling source for the mould
assembly. Another advantage in utilizing the arrangement is that the
relatively
lower volume of fluid to be required to be circulated through the fluid flow
chamber compared with the pressure chambers means that less fluid Is required
to effect changes in temperature resulting in faster cycling times.
A separate top fluid flow chamber may also be located over the lay-up.
The top fluid flow chamber may be in the form of a bladder formed of
elastically
deformable material. A face of the bladder may be generally configured to at
least generally follow the shape of the mould cavity when fluid is circulated
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
therethrough. The top fluid flow bladder may be located over the lay-up and
fluid
circulated at elevated temperature through the top fluid flow bladder while
the
mould assembly is located between the pressure chambers to thereby supply
heat to the lay-up. This provides for more uniform heat transfer, the top
fluid flow
5 chamber conforming closely to the lay-up. Therefore, the top fluid flow
bladder in
conjunction with the mould assembly having the attached fluid flow chamber
acts
to supply heat to both the lay-up and the mould section.
The fluid temperature circulating through the top fluid flow chamber may
also cycle between higher and lower temperatures as within the fluid flow
10 chamber of the mould assembly.
The mould assembly including the fluid flow chamber, with the top fluid
flow chamber located over the lay-up supported within the mould assembly may
also be located between the pressure chambers of the production system of the
present invention.
It is sometimes necessary to bond other component parts to the composite
or bonded metal component. These component parts can include stringers,
reinforcement ribs or attachment rings. It would be preferable to be able to
bond
these component parts at the time the component is being produced. This would
provide far superior bonding of the parts to the component.
Therefore, according to yet another aspect of the present invention, there
is provided a system for producing composite or bonded metal components, the
system including first and second pressure chambers, each pressure chamber
having an elastically deformable chamber wall; means for circulating fluid at
elevated temperature and pressure through each said pressure chamber, a
mould assembly including a mould cavity within which a composite or bonded
metal lay-up and at least one component part can be located, and a configuring
arrangement for positioning the component parts on said lay-up, wherein when
the system is in use, the pressure chambers are held together with the
elastically
deformable chamber walls located in opposing relation, the mould cavity
containing a said lay-up and at least one component part located in position
by
the configuring arrangement being accommodated between the chamber walls
while fluid at elevated temperature and pressure is circulated through each
CA 02617076 2007112-21
WO 02/058916 PCT/AiJ02/00078
11
pressure chamber such that the lay-up is compressed and cured or bonded and
the at least one component part is bonded thereto.
The component parts may include stringers, reinforcement ribs or any
other component that needs to be bonded to the composite or bonded metal
component.
A vacuum bag may be laid over the lay-up to allow for an initial
compression of said lay-up
The configuring arrangement may include at least one strap configured to
engage and locate the or each component parts in its desired position over the
lay-up. For exampie, when the component parts are reinforcement ribs, the
straps may extend laterally relative to the rib, the straps including one or
more "U"
shaped bends to engage the upstanding portion of the rib thereby locating the
rib
in position over the lay-up. The straps may be located on or under the vacuum
bag.
Alternatively, the configuring arrangement may be provided by the
chamber wall of the pressure chamber located over the mould cavity, the
chamber wall being configured to include pockets or channels for accommodating
and locating component parts over the lay-up. The pressure chamber may
include an outer housing or frame for accommodating a bladder bag, a face of
the
bladder bag providing the configured chamber wall. The bladder bag may be
initially located in position over the lay-up and component parts before the
outer
housing is located over the bladder bag. The bladder bag can then be fully
inflated by the circulating fluid. This arrangement makes it easier to locate
the
bladder bag and the cooperating component parts in position over the lay-up
prior
to inflation of the bladder bag. It is also envisaged that more than one
bladder
bag could be accommodated in the outer housing. This may allow this system to
be used on very large components where it would not be possible to use a
single
bladder only.
In another preferred embodiment, a further fluid flow bladder may be
provided, the fluid flow bladder being formed from elastically deformable
material
and may be adapted to conform or be readily conformable over the component
parts and the lay-up when laid over them. The bladder may have a relatively
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
12
narrow overall bladder thickness to thereby facilitate the conforming of the
bladder thereon. Fluid at elevated temperature and pressure may be circulated
through the fluid flow bladder.
The configuring arrangement further includes providing a configured
chamber wall of the pressure chamber adapted to conform with and urge the
liquid flow bladder more closely against the component parts and the lay-up
upon
which the component parts are located.
In another embodiment, the configuring arrangement may be in the form of
an internal support frame located within the pressure chamber locatable over
the
mould cavity. The internal support frame may be adapted to support an
elastically deformable chamber wall of that pressure chamber having a
configuration adapted to conform against the lay-up and component parts prior
to
the circulation of fluid through the pressure chamber. The configured chamber
wall moves away from the support frame to engage the mould assembly when
fluid is circulated therethrough and draws back onto the support frame when
there
is no fluid flow therethrough.
Location means may also be provided to accurately locate a mould section
on the chamber wall and maintain accurate alignment and dimensional stability
of
the mould in operation. The location means may simply be in the form of
attachment points on the chamber wall for the mould assembly. For example,
lugs, sockets, rings or pockets may be provided on the chamber wall to which
the
mould assembly could be secured. The attachment point can be tethered to the
pressure chamber housing using wire or other means. These help to generally
maintain the attachment points in their correct position. The location means
may
alternatively include a location frame located within the pressure chamber,
and
having at least one locating pin extending through the chamber wall of that
pressure chamber. A plurality of locating pins may preferably extend from the
chamber wall, each locating pin extending from the location frame. This
location
frame may be separate from the housing of the pressure chamber and may
therefore move independently from and may not be directly connected to the
housing. The location frame may also be tethered to the pressure chamber
housing to maintain it in the correct position therein. The location pins
therefore
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
13
may pass through the chamber wall and may be adapted to engage cooperating
apertures provided in a said mould section. The locating pins therefore locate
the
mould section in a specific place on the chamber wall.
This location arrangement also allows the pressure chamber walls to be
positioned at an inclined angle relative to a horizontal plane as the mould
section
can be maintained in position over the chamber wall though this is not
imperative
to the ability to incline the mould. The advantage of this inclined position
is that it
allows and encourages any air or gas remaining in the composite or bonded
metal lay-up to move up to the uppermost section of the lay-up as the rest of
the
lay-up is saturated with resin. This air is eventually pushed/driven out from
the
lay-up by the transferred resin. This results in a composite component with
fewer
air bubbles/voids.
The use of a location frame within the pressure chamber is acceptable as
long as the location frame can be readily accommodated with the pressure
chamber. It is preferable that the volume of the pressure chamber, through
which
the circulating fluid flows not be increased to support a larger location
frame. This
is because a larger amount of fluid will need to be circulated through the
pressure
chamber which can be undesirable.
Therefore, according to a further aspect of the present invention, there is
provided a system for producing a composite or bonded metal components
including:
first and second pressure chambers, each chamber having an elastically
deformable chamber wall;
means for circulating fluid at an elevated temperature and pressure through
each
said pressure chamber; and
at least one mould assembly including a mould section providing a mould cavity
within which a composite or bonded metal lay-up can be located,
location means for locating the at least one mould assembly in a fixed
position,
the pressure chamber being supported about the at least one mould assembly in
a floating relation relative thereto;
wherein when the system is in use, the pressure chambers are held together
with
the elastically deformable walls located in opposing relation, the at least
one
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
14
mould assembly containing said lay-up being accommodated between the
chamber walls while fluid at elevated temperature and pressure is circulated
through each pressure chamber such that the lay-up can be compressed and
cured or formed.
The mould assembly may be fixed in position by a location frame rigidly
supported outside of the pressure chambers. The volume of the pressure
chamber does not therefore need. to be included to accommodate a location
frame therein. The mould assembly may be supported by at least one support
post of the location frame extending through at least one of the pressure
chambers.
This system operates in an opposite manner to the earlier described
arrangement in that the mould assembly is held fixed whereas the pressure
chambers can float about the mould assembly. By comparison in the earlier
arrangement, the pressure chambers are fixed in position, with the mould
assembly floating between the pressure chamber walls. The manufacturing
process is however still the same in both system arrangements.
In the abovedescribed arrangement, the mould assembly is rigidly
supported with the mould system being supported on the location frame. It is
however also envisaged that only one pressure chamber be used, the pressure
chamber being locatable over the rigidly supported mould assembly.
Therefore, according to another aspect of the present invention, there is
provided a system for producing a composite or bonded metal components
including:
a fixed mould assembly including a mould section providing a mould cavity;
a pressure chamber having an elasticaliy deformable chamber wall; and
means for circulating fluid at an elevated temperature through the pressure
chamber;
wherein when the system is in use, the pressure chamber is located over the at
least one mould assembly with the chamber wall located over the at least one
mould assembly, the mould cavity accommodating a said lay-up, and fluid at
elevated temperature and pressure is circulated through the pressure chamber
such that the lay-up can be compressed and cured or formed.
.._-_------
CA 02617076 2007-12-21
The pressure chamber may be located in floating relation over the mould
assembly. The pressure chamber may therefore move relative to the fixed mould
assembly when fluid is circulated therethrough.
The system does not provide for the balancing of forces applied to the
5 mould section. Nevertheless, the benefits achieved through the use of
circulating
fluid in the pressure chambers are still present making this system
particularly
useful for components not requiring dimensional accuracy.
The fluid circulating means including at a plurality of fluid reservoirs each
supporting fluid at differing relative temperatures, and flow control means
for
10 directing fluid of different temperatures to the pressure chamber. This
arrangement has been previously described in the Applicants U.S. Patent No.
6,149,844.
Means may be provided to provide a cyclically variable pressure in the fluid
15 within the pressure chamber. For example a vibration generator may be
15 secured to the pressure chamber to vibrate the pressure chamber and the
fluid
therein. The use of this vibration facilitates the removal of air bubbles
within the
composite or bond metal material. The use of vibration is generally applicable
to
all of the production systems according to the present invention.
It should be noted that the pressure chambers can even operate when in a
vertical position, with the chamber walls being located in a generally
vertical
plane. This demonstrates a key aspect of the system and method of the present
invention being the "ba.lanced density effect. This is where the pressure of
the
circulating fluid and the fluid pressure of the resin when in a liquefied
state are
generally balanced within the system because the density of the fluid and the
resin are similar. The density and viscosity of the liquefied resin is close
to that of
water .and the heat transfer fluid used. Therefore, the pressure applied by
the
circulating fluid to the liquefied resin is generally balanced even in
situations
where the pressure chambers are vertical or inclined. Although there would be
a
natural tendency for the liquefied resin to slump down towards the lower part
of
the mould section, the fluid pressure of the circulating fluid also increases
with
increasing depth in the pressure chamber. This results in a balancing of the
fluid
pressures between the liquefied resin and the circulating fluid along the
mould
section thereby counteracting the tendency for the slumping of resin towards
the
CA 02617076 2007-12-21
16
lower part of that mould section. The result is that it is possible to
maintain a
consistent thickness in the composite component produced in an inclined or
vertical pressure chamber according to the present invention. This process
overcomes many of the difficulties experienced with the prior art in that it
enables
large parts with deep sides to be constructed and not have the resin, due to
the
effect of gravity, run down the side of these deep faces resulting in
a"wicking" or
slumping effect wherein the resin flows down the wall, even with high levels
of
vacuum applied by vacuum bag, resulting in excess resin at the base of the
wall
and a shortage of resin at the top. To overcome this effect matched metal
moulds are generally employed to provide an enclosed rigid resin volume but at
consequent high cost. The present invention can therefore produce far larger
panels or other components than conventional composite production systems.
In another aspect of the invention the pressure chambers can be
progressively filled with fluid from the empty state to the full state. As the
column
of hot fluid fills the pressure chambers it presses against the bladder and
mould
walls compressing the laminate therebetween and melting the resin. It is
envisaged that this will result in a line or wave of resin moving in front of
the
raising column of fluid. This will tend to force the air out of the laminate
and result
in a controlled wet out of the part as the fluid column and thus resin column
rises
over the face of the part. This is not possible or practical using
conventional
systems of either rigid or flexible air filled bladders. The system of
balanced
density provides very accurate resin and fibre control of the laminate by
forming
around the part accurately to make up for variations in thickness and provide
even pressure and resin content over all the part from top to bottom.
The means for circulating the fluid may be the same as or similar to the
arrangement shown in U.S. Patent No. 6,149,844. The fluid may preferably be
oil.
The arrangement includes a series of fluid reservoirs each containing fluid
at differing temperatures. For example, three fluid reservoirs may be provided
containing fluid at a low and high temperature respectively, the third fluid
reservoir
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
17
containing fluid at a temperature intermediate the fluid temperature of the
other
fluid reservoirs.
Each pressure chamber and fluid flow chamber may be in fluid
communication to all the fluid reservoirs such that fluid at differing
temperatures
can be circulated therethrough. A series of fluid pumps and valves may be
provided for controlling the fluid flow from each reservoir. Each fluid
reservoir
may be pressurized so that the fluid being delivered from the reservoir is at
an
elevated pressure.
The advantage of this arrangement is that it is not necessary to heat and
cool the fluid within the system at each production cycle of a component
reducing
energy usage of the system.
Each fluid reservoir may be provided with a "ring main" so that a number of
production systems can be connected at any one time to the reservoirs.
The cycling of fluid at differing temperatures may be staggered between
each production system so that there is not an excess drain of fluid from any
fluid
reservoir at any one time. This also enables the curing process to start at
any
time and moulds once prepared do not have to wait for a curing cycle to finish
before a new cycle can commence which is ineeient in a fixed station design.
Furthermore, means may be provided to allow the pressure in the
chambers to be cyclically varied to produce vibration or pressure waves
through
the fluid through water hammer or piston or vibrating the mould directly
during at
least part of the duration of application of pressure in the pressure chambers
as
described in the abovenoted International Patent Application.
At least one mould assembly may be located between the pressure
chambers when the system is in use. It is also possible to have a number of
mould assemblies between the pressure chambers when in use to enable a
plurality of composite components to be produced at the same time.
The mould section(s) can be loaded with the composite lay-up or bonded
metal sheets prior to being located between the pressure chambers. This
therefore enables the ongoing preparation of further composite lay-ups within
mould sections while another composite lay-up is being compressed and cured or
formed. Furthermore, the use of separate mould sections allows different
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
18
composite components to be produced without changing the configuration of the
pressure chambers. This also allows the production of a plurality of composite
components at the same time if a plurality of mould assemblies can be located
between the pressure chambers.
A vacuum film may also be placed over the composite lay-up, with the =
edges of the film being sealed against the mould section. Air may then be
extracted from under the vacuum film to thereby remove as much of the air and
other gases as possible from the composite lay-up. This helps to minimize the
amount of air bubbles/voids within the final composite component. It should
however be noted that the use of the vacuum film is not essential to the
operation
of the present invention.
Once the mould assembly is located between the pressure chambers, the
introduction of pressurised fluid into the chambers urges the elastically
deformable chamber walls to deform about the mould assembly such that a
pressure is applied to the composite lay-up located in the mould section(s),
the
shape of the final composite component being defined by the shape of the mould
section(s). The outer surfaces of these mould section(s) are preferably smooth
to ensure that their surfaces are slippery to the elastically deformable faces
of the
pressure chambers. With this slip the elastic deformable pressure chamber
walls
can slide into close contact with the shape of the mould section(s) and impart
the
maximum force and heat to the mould section(s) with the least distortion. To
enhance this process a lubricant can be applied to the mould section(s) or the
pressure chamber wall. In addition or as part of the lubrication to obtain
maximum heat transfer from the fluid within the pressure chambers to the mould
section(s) and the component within the mould it is preferable to have a fluid
or
transfer medium to transfer the heat. Once the elastically deformable walls
have
come into close contact with the mould section(s), the pressure from within
the
pressure chamber compresses the composite lay-up or bonded metal component
thereby removing excess resin or bonding medium and air bubbles therefrom. As
previously described above, the mould assembly could alternatively include a
mould section having a fluid flow chamber. Furthermore, a top fluid flow
chamber
could also be located over the mould assembly. This mould assembly and
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
19
optionally the top fluid flow chamber can then be located between the pressure
chamber walls to compress and cure the lay-up located in the mould assembly.
The application of a cyclically variable pressure or vibration producing
pressure
waves through the fluid or vibration of the mould assembly itself facilitates
the
removal of air bubbles ensuring that the final composite/bonded metal
component
has very un'rform material properties therethrough. Furthermore, because the
fluid is circulated through the pressure chamber, this ensures that there is
relatively rapid and uniform heating and cooling of the composite lay-up or
bonded metal component along its entire surface ensuring uniform curing and
cooling of the lay-up/part/metal componen.t. In addition, at any point in the
cycle,
the fluid flows can be stopped and intemal heaters used - to maintain the
temperature to fully cure the part.
The composite lay-up may include layers of resin impregnated material
(known as "prepreg") or layers of metal sheet. Reinforcements for the final
composite component and other dry fibers may also be included in the lay-up. A
peel cloth and bleeder cloth may then be placed over the composite lay-up
where
required. The resin matrix or bonding medium in the form of resin is provided
within the prepreg thermoplastic sheet or metal sheet. It is however also
envisaged that at least a significant amount of the resin matrix or bonding
medium be supplied to the composite lay-up once it has been applied to the
mould section(s). The composite lay-up may be a relatively dry "preform"
formed
from layers of or plies of continuous fibres. The resin matrix or bonding
medium
may be supplied to the mould section(s) after the dry preform has been located
between the chamber walls by means of one or more supply lines or sprues. This
enables the system according to the present invention to utilize what is known
as
a resin transfer moulding (RTM) process for producing the composite component.
According to yet another aspect of the present invention, there is provided
a method of producing composite or bonded metal components including:
locating a composite or bonded metal lay-up in the mould cavity of a mould
assembly; locating the mould assembly together with the composite or bonded
metal lay-up between first and second pressure chambers at least substantially
filled with fluid, each pressure chamber having an elastically deformable
chamber
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
wall, the chamber walls being located in opposing relation with the mould
assembly located therebetween; supplying resin to the mould assembly and
through the lay-up located therein; collecting the overflow of resin from the
mould
assembly for subsequent supply to another mould assembly; and circulating
fluid
5 at an elevated pressure and temperature through each pressure chamber such
that the lay-up and is compressed and cured or formed.
The steps of collecting and supplying the overflow of resin from one mould
assembly to another mould assembly may follow sequentially over one or more
further mould assemblies.
10 This can lead to a significant reduction in the amount of resin wasted when
resin is supplied separately to a number of mould assemblies using RTM.
Resin may be supplied under pressure from a first resin container to a first
mould assembly, the amount of resin being supplied being greater than that
required for the lay-up in the first mould assembly. The result is a wave or
resin
15 traveiing through the mould assembly. This resin wave may include a moving
front of resin containing excess resin and may be in the form of a thick
wavefront
of resin passing therethrough. The mould assembly may be held in an inclined
position such the pressure of the fluid, which increases with depth in the
fluid,
helps to force the resin up through the lay-up. The overflow of resin from the
first
20 mould assembly can then be supplied to subsequent mould assemblies. Air
would be pushed out of the lay-up by the traveling resin wavefront reducing or
eliminating air bubbles in the final component. This excess resin may be
initiaiiy
delivered to a subsequent resin reservoir which may be under vacuum. Further
resin may be squeezed from the lay-up when a valve closes off the first resin
container and pressure is applied to the mould assembly, this additional resin
being collected in the subsequent resin reservoir. A valve controlling the
resin
flow from the subsequent resin reservoir to the next mould assembly may be
opened and resin can be pumped under pressure into the next mould assembly.
This can continue over several mould assembiies if required.
The use of a wavefront of resin moving through one mould assembly after
another therefore acts to minimize the wastage of resin that could occur if
each
mould assembly is supplied separately.
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
21
Another way of supplying resin to the dry preform is by way of a plurality of
solid resin blocks or tiles which can be distributed over the surface of the
dry
preform which is itself supported in a mould section. The mould section
supporting the dry preform and blocks/tiles of resin can then be located
between
the pressure chambers, and the resin is then melted by circulating fluid at an
elevated temperature through the pressure chambers. The system according to
the present invention can therefore al.so utilize what is known as a resin
film
infusion (RFI) process.
It has been found that the RTM process can produce a relatively brittle
composite product. This is because the resin must be able to be readily
transferred lengthwise along the plane of the composite lay-up. The resin must
therefore be of a "short molecular chain" type to enable ready transfer of the
resin
through the lay-up. The resultant product can be relatively brittle.
By comparison, because the RFI process distributes solid resin blocks over
the composite lay-up, the resin, when melted only needs to wet the area of the
composite lay-up immediately adjacent to the resin block. The resin can
therefore be a"toughened" type having relatively longer molecular chains. The
resultant composite product produced in a RFI process can have greater
structural strength than products produced using a RTM process.
Although the RFI process can produce an improved composite product, it
can be labour intensive because of the need to manually distribute the resin
blocks over the dry preform.
Therefore, according to a further aspect of the present invention, there is
provided a method of producing composite or bonded metal components
including:
applying a layer of solidified resin over a mould surface of at least one
rigid or
semi-rigid mould section;
locating a composite or bonded metal lay-up in said at least one rigid or semi
rigid
mould section;
locating the at least one mould section together with the lay-up between first
and
second pressure chamber, each pressure chamber having an elastically
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
22
deformable chamber wall, the chamber walls being located in opposing relation
with the at least one mould section located therebetween; and
circulating fluid at an elevated pressure and temperature through each
pressure
chamber such that the resin layer is liquefied and the liquefied resin is
transferred
into the lay-up and is compressed and cured or formed.
The viscosity of the resin varies substantially with temperature. Therefore,
heated resin in a liquefied state can be sprayed onto the mould surface. This
surface may be at a lower temperature than the resin. Means may be provided to
chill the mould section. This results in the solidification of the resin into
a layer on
the mould surface. One way of allowing the precooling of the mould section is
to
provide cooling passages or cavities within the mould section through which
fluid
can be circulated. These cooling passages may be provided immediately under
the mould surface to maintain that surface at the required temperature. In
another application the mould may be sited upon a separate bladder that is
chilled and on the carrier holding the mould.
This method provides a product similar to that produced by the RFI
process. The method according to the present invention is however less labour
intensive.
The resin can be of very high viscosity that at low temperature and without
vibration, sticks and readily adheres to the mould to build up a thick layer
and
maintain high thixostropy, that is not to slump or fall off the mould surface.
The
physical behaviour of the resin is wax-like in characteristics. The dry fiber
reinforcing and prepreg or wet lay-up material can then be placed within the
mould. The mould section can then be placed within the pressure cell. Once in
position the pressure can be applied and the temperature increased, to rapidly
melt the resin reducing its viscosity and wetting out the fiber reinforcement.
There can be sequential heating of the mould section, with the composite lay-
up
being initially heated to prepare it for subsequent wet out by the resin. The
resin
will more easily wet a heated composite lay-up. Heat may then be subsequently
applied to the mould section to liquefy the resin layer and allow the resin
transfer
to occur. It may be preferable to locate a transfer control means such as a
Keviar
veil between the resin layer and the composite lay-up. This veil prevents the
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
23
transfer or resin until the resin is at a low enough viscosity to readily wet
out the
composite lay-up. This minimizes the possibility of dry spots in the composite
lay-
up that can occur if the resin is too viscous.
The mould section can also be vibrated to spread and liquefy the resin and
remove any entrapped air. In this way the resin layer is liquefied, forced out
into
the dry fiber reinforcements, the air driven out of the laminate, the laminate
compressed and the part cured.
Separate supply lines may respectively supply a resin and a catalyst to a
spray head. The resin and catalyst can be mixed while passing through the
spray
head. It is however also envisaged that different resins may be sprayed
simultaneously or alternatively by the spray head on the mould surface, the
resins
reacting to form the resin layer. The resin may also be sprayed in different
spray
patterns over the mould surface to provide areas of different-resin thickness
in the
final resin layer. This enables the correct amount of the resin to be supplied
to
areas of a composite lay-up having varying thicknesses. Also, this enables
"prepacks"' to be properly impregnated with precisely placed and measured
amounts of resin and then cured. The spraying process combined with the
ability
to "freeze" or chill the resin into position as it hits the mould or shortly
thereafter
provides for very accurate placement of the resin into the position on the
mould to
accurately wet out the prepack by driving or transferring the resin into the
prepack
as it is melted. This has been referred to as Resin Spray Transfer or RST.
These
prepacks include preinstalled components such as attachment lugs and so on
and therefore require different amounts of resin to be supplied to different
areas
of the prepack.
An important advantage of the resin characteristics is that because the
resin solidifies as soon as it contacts the chilled surface, it enables the
lay-up to
be immediately held in position in the mould. This is advantageous where the
surface is inclined or vertical.
The apparatus used to spray the resin may be heated and cooled by the
fluid supplied from the same fluid circulation system used to circulate fluid
through
the pressure chambers. To this end, the resin supply.line may include an outer
conduit through which fluid is circulated and an inner conduit located at
least
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
24
generally concentrically within the outer conduit. The resin is supplied to
the
spray head through the inner conduit. Fluid at elevated temperature can be
circulated through the outer conduit when the resin needs to be maintained in
a
liquid state. This arrangement ensures that there is uniform heating of the
resin
within the inner conduit as the resin flows therethrough. Fluid at elevated
temperature can also be circulated about the spray head and about a resin
hopper where solidified resin is initially heated and melted before being
supplied
to the resin line. The hopper may include outer hollow walls though which the
fluid circulate. Alternatively, tubes through which the fluid can circulate
may
extend around the hopper wall.
The temperature of the fluid circulating through the resin spray apparatus
can be adjusted to avoid the curing of the resin within the system. Cooler
fluid
can be circulated though the apparatus when no resin is being sprayed to stop
any curing reaction of the resin.
Other means for applying a resin matrix bonding mediums to the
composite lay-up are also envisaged. For example, this material can be in the
form of a power or a film or wet out of a cloth or as part of a thermoplastic
sheet
applied over the composite lay-up.
The present invention allows for a semi-continuous production of
composite components facilitating mass production of such components.
Therefore, according to a further aspect of the present invention, there is
provided a method for producing composite or bonded metal components
including:
preparing and locating a composite or bonded metal lay-up in the mould cavity
of
a plurality of mould assemblies;
locating one or more mould assemblies between two separated pressure
chambers, each pressure chamber having an elastically deformable chamber wall
bringing the pressure chambers together in a production stage such that the or
each mould assembly is located between the chamber walls of the pressure
chambers;
_ , ,......_.... .... . _ ..
CA 02617076 2007-12-21
circulating fluid at elevated temperature and pressure through each pressure
chamber during said production stage to thereby compress and cure or form the
component;
remQVing the or each mould assembly from between the pressure chambers;
5 separating the completed component from the or each mould assembly; and
replacing the or each mould assembly with a further one or more mould assembly
accommodating a said lay-up for a following production stage.
The mould assembly may include at least one mould section.
Altematively, the mould assembly may include a mould section having a fluid
flow
10 chamber as previously described.
The fluid may be circulated by a fluid circulation means including a plurality
of fluid reservoirs, each containing fluid at relatively different
temperatures, and
fluid supply means for controlling the fluid flow to the pressure chambers and
fluid
flow chamber as required. Each fluid reservoir may include a ring main to
15 facilitate supply of fluid to a plurality of pressure chambers.
The abovedescribed method allows for a semi-continuous process for the
production of composite or bonded metal components because the mould
assemblies can be prepared beforehand.
It is also envisaged that the production system described in U.S. Patent
20 No: 6,149,844 would be adapted to provide for semi continuous process.
Therefore according to another aspect of the present invention, there is
provided a method for producing composite or bonded metal components
including:
preparing and locating a composite or bonded metal lay-up in the mould cavity
of
25 a plurality of mould sections, each mould section being resiliently mounted
and
forming a chamber wall of a bottom pressure chamber respectively;
locating each said bottom pressure chamber under a separate top pressure
chamber including an elastically resilient chamber wall, said chamber wall
being
located over the mould cavity, bringing the top and bottom chambers together
in a
production stage such that the chamber wall of the top chamber is located over
the mould section;
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
26
circulating fluid at elevated temperature and pressure through the top and
bottom
pressure chambers during the production stage to thereby compress and cure or
form the component, and
replacing the bottom pressure chamber with -another bottom pressure chamber
accommodating a said lay-up for the next production stage.
The bottom pressure chamber may be mounted for at least generally
horizontal movement to enable each bottom pressure chamber to be located
under the upper pressure chamber which may be located in one position and
moveable in an at least generally vertical position.
For example, the pressure chamber may support wheels or be mounted on
a trolley.
Fluid supply lines may. be secured to the upper pressure chamber. The
fluid supply lines may be respectively connected to and released from each
bottom pressure chamber as they are moved under the upper pressure chamber.
It is however also envisaged that the bottom pressure chambers be held
stationary and the upper pressure chamber moveable over each bottom pressure
chamber.
In certain applications, it may be acceptable to utilize a production system
utilizing a single pressure chamber as previously described.
Therefore according to a further aspect of the present invention, there is
provided a method for producing composite or bonded metal components
including:
preparing and locating a composite or bonded metal lay-up in the mould cavity
of
a plurality of rigidly mounted sections;
locating each said mould section under a top pressure chamber including an
elasticity resilient chamber wall, said chamber wall being located over the
mould
cavity, bringing the top pressure chamber down onto the mould section in a
production stage such* that the chamber wall of the top chamber is located
over
the mould section;
circulating fluid at elevated temperature and pressure through the top
pressure
chamber during the production stage to thereby compress and cure or form the
component, and
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
27
replacing the mould section with another mould section accommodating a said
lay-up for the next production stage.
The structural strength of the mould section could be increased in another
preferred embodiment of the mould section. This mould section may include an
inner mould skin providing the mould cavity, an outer mould skin on the
opposing
side of the mould section, and a series of reinforcement fins extending
between
the inner and outer mould skins. The inner mould skin may be thicker than the
outer mould skin for dimensional accuracy. The reinforcement fins act to
provide
a series of box structures within the mould section. This is because the
reinforcement fins also act as heating or cooling fins improving the heat
transfer
efficiency to the mould section. Fluid at elevated temperatures can also be
circulated though these box structures. The outer mould skin can also be
provided with an insulation layer.
The reinforced mould section is more rigid than typical single wall mould
sections as well as having better heat transfer efficiencies
It will be convenient to further describe the invention with respect to the
accompanying drawings which illustrate preferred embodiments of the composite
or bonded metal production system according to the present invention. Other
embodiments of the invention are possible, and consequently, the particularity
of
the accompanying drawings is not to be understood as superceding the
generality
of the proceeding description of the invention.
In the drawings:
Figure 1 is a side cross-sectional view of a system for producing composite or
bonded metal components according to the present invention;
Figure 2 is a side cross-sectional view of one of the pressure chambers of the
system of Figure 1;
Figure 3a and 3b are side cross-sectional views of co-operating mould sections
for producing a boat hull and deck moulding respectively;
Figure 4 is a top view of a pressure chamber of the system of Figure 1
supporting
a large deck mould assembly;
Figure 5 is a pressure chamber of the system of Figure 1 supporting a
plurality of
mould assemblies;
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
28
Figure 6 is a schematic view of a semi continuous production process using the
system according to the present invention.
Figures 7 to 10 are schematic cross-sectional views show in more detail the
production process according to the present invention utilizing a mould
section
with a resin layer on the mould surface;
Figure 11 is a schematic view of a resin spraying apparatus for the production
process of Figure 7 to 10;
Figures 12 and 13 illustrate the principle of the balanced density effect;
Figures 14 is a schematic cross sectional view of a mould assembly having a
fluid
flow chamber according to the present invention;
Figure 15 is schematic view of the mould assembly of Figure 14 located between
pressure chambers according to the present invention;
Figures 16 to 19 are schematic views of alternative means for locating a mould
assembly on a chamber wall;
Figures 20 to 21 b are schematic views showing another embodiment of a
production system according to the present invention;
Figure 22 is a schematic view showing a further embodiment of a production
system according to the present invention;
Figures 23 and 24 are schematic views showing a resin supply arrangement for
systems according to the present invention;
Figures 25 to 28 are schematic views showing alternative configuring
arrangements for locating component parts on a lay-up;
Figures 29 to 31 are schematic views of semi-continuous production systems
according to the present invention; and
Figure 32 is a schematic cross-sectional view of a mould section having
internal
fins.
The composite components production system according to the present
invention includes separate upper and lower pressure chambers 1, 2, one of
said
chambers being shown in Figure 2. Each pressure chamber includes a main
housing 3 supporting an elastically deformable and readily conformable chamber
wall 5. The top pressure chamber 1 can be located over the bottom pressure
chamber 2 with their respective elastically deformable and readily conformable
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
29
chamber walls being located in opposing relation. Mould section assemblies 7,
9
can be located between the opposing chamber walls 5. Each mould assembly
may typically include an upper mould section and lower mould section as for
example shown in Figures 3a and 3b. Figure 3a shows a mould assembly 7 for
producing a boat hull including an upper mould section 7a and lower mould
section 7b. A composite lay-up may be located between the upper and lower
mould sections 7a, 7b. This composite lay-up may typically include resin
impregnated material, dry fibres, and reinforcement materials. Figure 3b shows
a
mould assembly 9 including an upper mould section 9a and lower mould section
9b for producing a deck moulding for the boat. A composite lay-up may also be
provided between the upper and lower mould sections 9a, 9b.
With the top pressure chamber 2 removed, the mould assemblies can be
placed on top of the elastically deformable chamber wall 5 of the bottom
pressure
chamber 2. Figure 4 shows the bottom pressure chamber 2 supporting a single
large deck mould assembly 11 which covers most of the surface area of the
chamber walls 5. It is however possible to locate a number of smaller mould
assemblies 13, 15, 17, 19 on top of the chamber wall 5 of the bottom chamber 2
as shown in Figure 5.
Once the mould sections have been located on the bladder or deformable
wall of the bottom pressure chamber 2, the top pressure chamber 1 can then be
laid over the bottom pressure chamber 2 as shown in Figure 1. Fluid such as
water or oil is then circulated through the inner volume 6 of both the upper
and
lower pressure chambers 1, 2. This circulating fluid is provided at an
elevated
temperature and pressure. Because the fluid in each pressure chamber is at an
elevated pressure relative to ambient pressure the elastic walls of the
pressure
chamber are forced out and deformed over the adjacent mould assemblies 7, 9,
this results in the compression of the composite lay-up there between. The
elevated temperate of the fluid acts to cure/form the resin matrix or bonding
medium within the composite lay-up. The pressure within the internal volumes 6
of both the upper and lower pressure chambers 1, 2 maybe at least
substantially
equal to thereby provide a balanced force on the mould assemblies 7, 9. This
allows the moulds to be of a lighter construction and still maintain
dimensional
....-,..:__.. , . ----....__.... ._.,._...---------
CA 02617076 2007-12-21
accuracy then otherwise would be the case where there is uneven pressure
between the pressure chambers 1, 2. The pressure within each pressure
chamber 1, 2 can also be cyclically varied or a vibration or pressure wave
introduced into the fluid of the, pressure chambers by the use of a piston or
other
5 type of vibration source attached to the mould assembly itself to thereby
apply a
vibrating force on the mould assemblies 7, 9. It has been found that this
assists
in removing air bubbles from the composite lay-up thereby ensuring a more
consistent and uniform final composite product. This vibration also enhances
the
release of the air from the laminate when RTM, RFI, or RST is being employed
10 and the mould is inclined or vertical. This vibration enhances the natural
tendency of the air bubble to release from the laminate and rise to the top of
the
column of liquid resin. The arrangement for circulating fluid at an elevated
pressure and temperature and providing a cyclically varying pressure is
already
described in detail In the Applicant's U.S. Patent No. 6,149,844 and will not
15 therefore be described herein.
Figure 6 shows a semi-continuous production process using the composite
component production system according to the present invention. The pressure
chamber assembly or cell providing the composite or metal bonded components
production system is located at Point E of the production flow. The system is
20 shown supporting a mould assembly therein. During the curing cycle process
when fluid is circulated through the pressure chambers to allow production of
a
composite component, another mould assembly can be prepared for introduction
into the cell at point D. To more fully describe the production flow the
process
commences at Point A, the mould assembiy is held in a mobile cradle to support
25 it and if necessary rotate it to enable effective access to all the
surfaces of the
mould assembly. Here the mould assembly is comprised of more than one mould
section, the mould assembly is initially prepared with the mould sections
being
waxed and prepared as so required. At Point B. the mould sections can be
sprayed with gel coat and resin If applicable. At Point C, the lower mould
section
30 is loaded with a composite layer which may include resin impregnated
material
(known as "prepreg"), reinforcement material foam cores and dry fibres as so
required. At Point D, the upper mould section, vacuum bag, or, a lid or
separate
mould to spread the load is located over the lower mould section, or the mould
is
.. . __ _ . . ..___.. ....,......__ _
CA 02617076 2007-12-21
31
simply left open to be compressed by the elastic wall of the opposing pressure
chamber. The final mould assembly is then ready for location between the
pressure chambers at Point E. Resin lines may be inserted into, on or on the
outside. of the mould sections dependent upon the application to allow for the
supply of resin matrix or bonding mediums such as resin, or the draining of
any
excess resin matrix or bonding medium as so required. Following the
production/curing of the composite component at Point E, the mould assembly is
removed from between the upper and lower pressure chambers and returned to
its holding cradle at Point F where -the lid, top mould, or vacuum bag, or
resin
lines, etc. dependent upon application are removed along with all the
disposable
moulding materials, peel ply, bleeder cloth, etc if applicable to that
application. It
should be noted that it is envisaged that no disposable materials will be
required
when the process is operated using RTM, RFI, or RST as a neat part should
result from the process. At Point G. additional reinforcements stiffeners,
strongbacks and bulkheads and interiors may be located and bonded within the
boat, as required; preferably this employs the bonding and joining process as
set
out in the Applicants' abovenoted Canadian Patent Application No. 2,401,811.
In
addition the deck stili within its mould assembly can also be bonded onto the
hull
before the hull is removed from the mould. Finally, at Point H. the completed
composite part is removed from the mould sections. In general this wili
require
the moulds to be split and the boat removed from the mould. The moulds are
then returned to Point A where they are once again cleaned, rejoined and
prepared for the moulding curing process.
Figures 7 to 11 show in more detail a. possible manufacturtng sequence
using the production process according to the present Invention where mould
sections having a sprayed resin layer using RST applied on the mould surface
are used.
Referring initially to Figure 7, a mould section 25 is supported on a
movable trolley 21. The mould section 25 includes a mould surface 26 upon
which a composite lay-up will eventually be positioned. Prior to the laying of
the
composite lay-up, a spray head 20 is used to spray liquefied resin 24 over the
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
= 32
mould surface 26. The spray head sprays a mixture of resin and a catalyst
respectively supplied by separate supply lines 22, 23 to the spray head 20.
The
mixed resin and catalyst coalesces as it leaves the spray head and contacts
the
mould surface 26. The mould section 25 can include cooling passages or
cavities
27 or a separate cooling bladder sited on the trolley in contact with the
mould
immediately under the mould surface 26 to help maintain that mould surface at
a
lower temperature than that of the resin exiting the spray head. This helps to
solidify the resin on the mould surface 26 to thereby provide a resin layer
thereon.
The resin can be sprayed onto the mould surface in a predetermined pattern to
provide varying thickness of the resin layer on the mould surface 26. This is
particularly useful when the composite lay-up is in the form of a "prepack" of
fibres and foam. Such prepacks can typically include components such as
attachment lugs and so on which are prelocated in the prepack in the position
where the component will be located in the final product.
Referring to Figure 8, once the prepack 29 is located on the mould surface
26 over the resin layer, a vacuum film 30 is located over the top of the mould
section 25. This vacuum film 30 is sealed to the mould section 25 so that air
can
be evacuated from under the vacuum film 30. This helps to minimize the amount
of air and other gases located within the prepack. The prepared mould section
25
can then be lifted off the trolley 21 as shown in Figure 8 and located on the
elastically deformable chamber wall 5 of a lower pressure chamber 2. Located
within that pressure chamber 2 is a support frame 32 which is not physically
connected to the main housing 3 of the bottom pressure chamber 2. Extending
from the support frame 32 are a plurality of locating pins 31 which extend
through
the chamber wall S. These pins are adapted to engage a series of apertures
provided along the flange 28 of the mouid section 25 to securely locate that
mould section 25 on the chamber wall 5.
As the lower pressure chamber 2 is inclined at an angle relative to the
horizontal plane, the support frame 30 and locating pins 31 help to locate the
mould section 25 in position on the chamber wall 5.
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
33
Referring now to Figure 10, the top pressure chamber 1 is then located
over the bottom pressure chamber 2 with the mould section 25 located
therebetween.
The apparatus according to the present invention can then operate in the
manner previously described to compress and cure the preform or composite lay-
up. It is however preferable to vary the temperature of the fluid passing
through
the bottom and top pressure chambers 1, 2 as this helps to ensure uniform
transfer of resin into the prepack. It is preferable to initially apply heat
to the
prepack to prepare that prepack for wetting by the resin. The warming of the
prepack facilitates the flow of the resin therethrough. This can be achieved
according to the present invention by circulating higher temperature fluid
through
the upper pressure chamber 1, while maintaining the fluid circulating through
the
lower pressure chamber 2 at a relatively lower temperature.
Once the prepack 29 has. been properly heated, warmer fluid can be
passed through the bottom pressure chamber 2 to heat the mould section 25 and
therefore the resin layer thereon. The heating of the resin layer results in
the
liquefication of that layer and the subsequent wetting of the adjacent prepack
via
that resin. Because the prepack has been preheated, this results in more ready
transfer of resin into the prepack. It is envisaged that the resin will be
heated and
liquefied at the base of the mould first so as to provide a heat transfer
effect from
one side of the prepack to the other to fully melt and liquefy any resin
within the
prepack. Also as the resin melts and reduces its viscosity it will fully fill
the
prepack with resin. It is most advantageous to commence this process at the
lowest point within the mould to drive the air and other gasses in front of
the
advancing melt line and upwards towards the top of the resin column and the
top
of the mould.
The sequential heating during the production process enhances the natural
tendency of the laminate and resin column to release air and have it rise to
the
top of the resin column where the pressures are balanced, these two natural
phenomenon minimizes the possibility of the slumping or wicking of the resin
that
can occur if the resin is liquefied too early leading to improper wetting of
the
prepack. It may also be beneficial to provide a Kevlar veil between the resin
layer
CA 02617076 2007-12-21
34
and the prepack prior to insertion into the mould section 25 between the
pressure
chambers. This veil includes a plurality of apertures which are sized to
prevent
the transfer of resin therethrough until the resin is at the right viscosity
to properly
wet out the prepack. If the resin is too viscous, this can result in dry spots
in the
5. prepack and therefore improper wetting of that prepack. The use of the
Keviar
veil therefore ensures that the resin is at a low enough viscosity to readily
wet the
prepack.
Figure 11 shows in more detail the resin spray apparatus used to spray the
resin onto the mould assembly.
A resin hopper 33 is used to melt the resin for the spraying process. The
resin 34 is obtained in block form. Such resin is typically relatively low in
cost to
purchase and of the long chain resin type. This type of resin is tougher than
that
typically used in RTM. Furthermore, solid resin products have an extended
shelf
life when compared with liquid resin. A resin pump 35 is located downstream of
the hopper 33 to deliver liquefied resin to the resin supply line 22 and spray
head
20.
The hopper 33 is provided with hollow walls 36 throu.gh which fluid from
the fluid circulation system used to supply fluid to the pressure chambers can
be
circulated. Tubes 37 can aitematively extend around the hopper 33, and fluid
can
be circulated though these tubes 37.
The resin supply line 22 includes an outer conduit 22a and an inner
conduit 22b located within and at least generally concentric with the outer
conduit
22a. The resin flows though the inner conduit 22b while fluid is circulated
through
the outer conduit 22a. The outer conduit 22a also extends about the spray head
20. Therefore, when resin is required to be sprayed by the apparatus, fluid at
elevated temperature is supplied through a supply line 38 which is connected
to
the outer conduit 22a of the resin supply line 22 and through the hollow wall
36 or
fluid tubes 37 of the hopper 33, the fluid retuming through a fluid drain line
39.
This fluid circulation arrangement provides uniform heating along the supply
path
of the resin and eliminates any hot spots that can arise if electrical heating
is
used. The spray head 20 can then be actuated by a gun handle and trigger
control 20a to emit a resin spring 24 therefrom.
-------------
CA 02617076 2007-12-21
When no resin spray is required, fluid at a lower temperature is circulated
through the apparatus to prevent curing of the resin retained therein.
The spray head 20 has a discharge aperture which can be controlled
electronically to provide resin sprays of varying widths. This enables the
spray
5 head 20 to deliver narrower and wider resin sprays as the spray head
traverses
the mould.
As previously noted, the present invention utilizes a "balanced density"
effect which allows the mould assembly to be mounted at an inclination or even
vertically. This enables the system according to the present invention to
produce
10 panels in vertical mould assemblies of far larger size than when using
conventional manufacturing processes. This effect is described with reference
to
Figures 12 and 13.
Figure 12 is a representation of the interface between a resin containing
volume 6a and air containing volume 6b separated by a flexible diaphragm, 5a.
15 The diaphragm 5a is held in a vertical position but is forced to bulge out
into the
air volume 6b, as the resin containing volume 6a is progressively filled, the
bulge
being the greatest near the bottom. This is because of progressively
increasing
pressure against the wall 5a with depth due to the weight of the column of
resin
6c. The reason for this is because the density of the air is less than that of
the
20 resin. The pressure of the air applied against the diaphragm 5a is
insufficient to
compensate for the pressure applied by the resin column 6c resulting in
distortion
of the diaphragm 5a.
Figure 13 is a representation of the interface between the resin containing
volume 6a, for example a mould cavity containing a lay-up, and a fluid
containing
25 volume 6b, for example, the pressure chamber. The flexible diaphragm 5a
separating the two volumes is for example provided by the elastically
deformable
chamber wall of the pressure chamber. Because the fluid is typically oil, the
density of the fluid is similar to the resin. Therefore, while the pressure
applied by
both the resin column and the fluid column against the diaphragm increases
with
30 increasing depth therein, there is no bulge In the diaphragm 5a. This is
because
the respective pressures applied by the resin and fluid columns against the
diaphragm 5a are balanced. Therefore, the circulation of fluid in the pressure
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
36
chambers according to the present invention can utilize this balanced pressure
effect allowing the mould assemblies to be inclined or held vertical with
minimal
distortion to the chamber walls.
Figure 14 and 15 show details of another preferred embodiment of the
system according to the present invention. Corresponding reference numerals to
the earlier embodiment are used in these figures and in subsequent figures for
clarity reasons.
Figure 14 shows a mould assembly 50 including a mould section 51
having a mould cavity 53 within which is supported a composite or bonded metal
lay-up 55 .~ This mould assembly includes two relatively deep channel portions
57.
Unlike the arrangement shown in Figure 1, only a single mould section is
provided. There may be an initial compression of the lay-up 55 using a vacuum
film as previously described and shown in Figure 8.
The deep channel portions 57 and the various ninety degree angles in the
cross section of the mould portion 51 makes it difficult for the chamber walls
5 of
the pressure chambers 1, 2 completely contact all the areas of the mould
assembly 50. The result is potentially less than satisfactory compression and
curing of the lay-up 55 because the heat and pressure has not been evenly
applied thereto.
Therefore, mould assembly 50 further includes a bladder 59 formed of
elastically deformable material and secured to the mould section 51 to thereby
provide a fluid flow chamber 61. Support membranes 63 interconnect the bottom
mould section f4pe- -with the bladder 59, This bladder includes means (not
shown) to allow fluid at elevated temperature and pressure to be circulated
through the fluid flow chamber. This therefore allows for a direct contact of
the
circulating fluid to the bottom mould face 52 ensuring a more efficient and
uniform
heat transfer to the mould section 51 and lay-up 55.
It is also envisaged that the fluid flow chamber be provided by a rigid or
semi-rigid housing or plate having a rigid face, the housing or plate being
resiliently attached along it's periphery to the mould section 51. Support
membranes may interconnect to the housing or plate and the mould section face
52 to thereby help to guide the fluid flow through the fluid flow chamber.
CA 02617076 2007-12-21
WO 02/0589 ] 6 PCTIAU02/00078
37
Referring now to Figure 15, during the production process for the
composite or bonded metal component, the mould assembly 50 is
accommodated between the chamber walls 5 of a top and bottom pressure
chamber 1, 2. A further top fluid flow chamber 65 can overlay the mould
assembly 50 when located between the pressure chambers. This top fluid flow
chamber 65 is in the form of a bladder formed of elastically deformabie
material.
The lower face 67 of the top fluid flow chamber 65 is configured to generally
conform with the shape of the mould assembly 50. This top fluid flow chamber
65
also includes means (not shown) for circulating fluid at elevated temperature
and
pressure therethrough.
This arrangement ensures that there is a relatively uniform pressure and
temperature distribution across the surface of the mould assembly 50 and the
lay-
up 55.
The advantage of this arrangement over the earlier described embodiment
is that there is now a separation of purpose between the pressure application
function of the pressure chambers 1, 2 and the temperature control function of
the
mould assembly fluid flow chamber 61 and top fluid flow chamber 65. The
relatively smaller volume of the fluid flow chambers 61, 65 result in a
smaller
volume of fluid being required to achieve the temperature changes for the
production process while at the same time maximizing the heat transfer to the
lay-
up 55. The function of the pressure chambers 1, 2 is then to apply the
pressure
for compressing the lay-up 55. The temperature within the pressure chambers 1,
2 can therefore be maintained at a constant temperature.
The embodiment of the production system shown in Figure 15 utilises a
top fluid flow chamber 65 having a configured bottom face 67. It is however
aiso
envisaged that the chamber wall 5 of the top pressure chamber 1 could
alternatively be configured to at least generally conform with the general
shape of
the mould assembly 50.
= Figures 16 to 19 show alternative location means for locating a mould
assembly 70 on the chamber wall 5 of a lower pressure chamber 2. The location
means acts to hold the mould assembly 70 in a predetermined position on the
chamber wall 5 to keep the mould assembly rigid.
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
38
In the embodiment shown in Figure 16, the mould assembly 70 is provided
with a number of lugs 71 which engage corresponding sockets 73 located on the
chamber wall 5.
Figure 17 shows the mould assembly 70 supporting a lay-up 72 therein,
located between top and bottom pressure chambers 1, 2. The lugs 71 of the
mould assembly 70 engages the sockets 73 supported on the bottom pressure
chamber 2. The chamber wall 5 of the top pressure chamber 1 is deformed into
the mould assembly 70 when fluid at elevated temperature and pressure is
circulated through the top pressure chamber 1. The chamber wall 5 of the
bottom
pressure chamber 2 is similarly deformed about the bottom of the mould
assembly 70 due to circulating fluid passing therethrough.
Figure 18 includes a rigid frame 75 having positioning pins 77 extending
through the chamber wall 5 of the bottom pressure chamber 2. This arrangement
is therefore similar to that shown in Figure 9 and 10 and the rigid frame 75
is
accommodated within but is otherwise not connected to the housing 3 of the
bottom fluid chamber.
The positioning pins 77 can engage corresponding apertures provided
along the periphery of the mould assembly 70. Because the rigid frame 75 shown
in Figure 15 has a relatively shallow profile, the volume within the bottom
fluid
chamber 2 does not need to be particularly high to accommodate the rigid frame
therein.
In the arrangement shown in Figures 19, the rigid frame 75 supported in
the bottom fluid chamber 2 is substantially larger in size requiring a greater
volume in the bottom pressure chamber 2 to accommodate that rigid frame 75.
Mould assemblies used in conventional autoclave composite production methods
typically have a large rigid frame of the type shown in Figure 19.
It is not advantageous to circulate a very high volume of fluid through the
bottom fluid chamber 2 because excess fluid is not provided for the production
process, this excess fluid being unnecessary. Therefore, it is preferable to
provide separation plates 79 located near the upper portion of the rigid frame
75
and seals 81 extending from the housing 3 of the bottom pressure chamber and
engaging a peripheral face of the rigid frame 75. The separation plates 79 and
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
39
seals 81 define a narrower fluid flow passage 80 through which circulating
fluid is
directed to thereby minimize the volume of fluid that needs to be circulated
at any
one time through the bottom pressure chamber 2, with fluid flowing over the
seal
81 and over the separation plates 79. Spacer plates 83 may also be provided
within. the defined flow path to assist in correctly positioning the
separation plates
79 as well as providing a degree of flow control for the flow passing through
the
fluid flow passage 80.
The separation plates 79 themselves may be provided by a pair of plates
with a peripheral resilient seal provided between the plates and extending
along
the periphery of said plates. The plates may be urged together, for example by
means of a nut and bolt to thereby compress the seal, the seal extending
beyond
the periphery of the plates to thereby engage the accommodating space within
the rigid frame 75.
The remaining volume of the bottom pressure chamber 2 can be filled with
material such as rocks or bricks to reduce the volume of fluid that needs to
be
retained therein.
In all of the abovedescribed arrangements, the mould assembly is held in a
floating relationship between the chamber walls 5 of the top and bottom
pressure
chambers 1, 2.
In another preferred embodiment of the system according to the present
invention, as shown in Figures 20, 21 a and 21 b, the mould assembly 17 could
be
held stationary while the top and bottom chambers 1, 2 are supported in a
floating
relation about the rigidly supported mould assembly 70. The mould assembly 70
is itself rigidly mounted on a support frame 85. This support frame 85 can be
secured to a floor by bolts 87. The mould assembly 70 is supported on the
support frame 85 via support pins 77 extending from the support frame 85 and
through the chamber wall 5 of the bottom pressure chamber 2.
The bottom pressure chamber 2 includes a peripheral flange 88. The
bottom pressure chamber 2 is supported on support posts 89 along its flange 88
with resilient means 91 such as a coil spring being provided therebetween so
that
the bottom pressure chamber 2 is movable relative to the stationary mould
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
assembly 70. The top pressure chamber 1 rests over the mould assembly 70 and
is also free to move relative to the mould assembly 70.
The rigid frame 85 includes a portion which is accommodated within the
bottom pressure chamber 2. To this end, the support frame 85 includes a series
5 of frame members 86 which extend through the housing 3 of the bottom
pressure
chamber, with seals 93 as best shown in Figures 18a and b being provided
around each frame member 86. Each frame leg 86 includes a flange connection
95 that allows the upper portion 97 of the support frame 85 to be installed
within
the bottom pressure chamber 2 and subsequently connected via the flange
10 connections 95 to the rest of the support frame 85.
Figures 21 a and 21 b shows in more detail the seal provided around each
support frame member 86. This seal 93 includes an annular rubber ring 95. The
inner peripheral edge of the annular ring 95 is trapped between a flange 97
fixed
on the frame member 86 and a second floating flange 99. The fixed flange 97
15 and floating flange 99 are bolted together to hold the inner periphery of
the
annular seal ring 95. The outer periphery of that seal ring 95 is secured
between
the housing wall 3 and an annular outer ring 100.
During operation of the production system shown in Figures 20 and 21a
and 21 b, fluid at elevated temperature and pressure is circulated through
both the
20 top and bottom pressure chambers 1, 2. Because the mould assembly 70 is
held
rigid, the top and bottom pressure chambers 1, 2 move with the change in
pressure in each pressure chamber to thereby balance the overall pressure over
the mould assembly 70 and the lay-up 72 located thereon. The resultant product
of this system therefore experiences the same uniform temperature distribution
25 and pressure as in the earlier described embodiments*and would therefore
have
similar if not identical physical characteristics to components produced using
the
earlier described production system.
Figure 22 shows another preferred embodiment of the present invention
which is similar to the embodiment of Figure 17 in having a rigid support
frame 85
30 rigidly supporting a mould assembly 70. In this embodiment however, only a
top
pressure chamber 1 is provided. In each of the preferred embodiments of the
production system according to the present invention, fluid is circulated at
CA 02617076 2007-12-21
41
elevated temperature and pressure through the production system. The -system
shown in Figure 19 simiiariy provides for the said circulation of fluid
through the
top pressure chamber 1. A vibration device can be supported on the pressure
chamber 1 to thereby vibrate the fluid circulating within the pressure
chamber.
This cyclic variation of the fluid pressure acts to remove any air bubbles
from the
lay-up.
The fluid circulation system shown in Figure 22 includes three fluid
reservoirs 105, 107, 109. Each of the fluid reservoirs are pressurized and
share
the same common pressure. The first fluid reservoir 105 provides fluid at a
relatively high temperature whereas the last fluid reservoir 109 provides
fluid at a
much lower temperature. The middle fluid reservoir 107 provides fluid at a
temperature intermediate the fluid temperatures of the first and last fluid
reservoirs 105, 109. A series of supply and return lines extend from each
fluid
reservoir with the fluid being supplied to and return from the top pressure
chamber I being controlled by means of valves (not shown) and a pump 111.
The valves control the temperature of the fluid passing through the fluid
supply
line 113 to the top pressure chamber 1. A fluid return line 115 returns the
fluid
back to the respective fluid reservoir. The fluid supply system acts to
connect
different reservoirs to the top pressure chamber 1 depending on the fluid
temperature required at the particular point in the production cycle. The
system is
described in more detail in the Appiicant's U.S. Patent No. 6,149,844.
The flrst circulation means provides a significant advantage in having very
little heat loss during operation with the production systems according to the
present invention. Conventional single bladder systems used in composite
production require the fluid to be cycled though a range of temperatures. The
fluid within the bladder must be initially heated and then allowed to cool.
The
heat is therefor lost in this process. By comparison, in the single pressure
chamber system shown in Figure 22, the fluid in each fluid reservoir of the
fluid
circulation system is maintained at a preset constant temperature. When fluid
of
a certain temperature is required to be circulated through the pressure
chamber,
the fluid reservoir containing the fluid at the correct temperature is
connected to
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
42
the pressure chamber. A different fluid reservoir is therefore connected as
the
fluid temperature requires a change in temperatures. There is therefore
minimal
loss in heat from the fluid contained in each fluid reservoir because the
fluid is
only circulated through the pressure chamber, the energy required to heat the
part is used and the fluid is not cooled. The result is that there is minimal
heat
loss when running a production system such as that shown in Figure 22.
The storage of fluid in this manner at conrolled temperatures is the
equivalent of
the storage of large quantities of energy that can be applied to heating and
or
cooling the mould and thus the part in the mould. As the fluid is changed,
that is
returned to the storage tanks, not cycled from cold, to hot to cold, there is
only the
heat inertia of the moulds and the part to be overcome. This is generally at
one
tenth to one third of the heat energy of the equivalent mass of water. This
approach results in rapid cycle times that would not be available if the high
heat
inertia of the HTF fluid is required to be overcome by cycleing its
temperature
from cold to hot to cold. Thus the approach of the separate storage of the
heat
transfer fluids results in a much faster and more efficient means of curing a
part
than the present bladder curing system.
The top pressure chamber 1 is held in a floating relation above the mould
assembly 70. This arrangement provides many of the advantages of the earlier
embodiments and is acceptable for components where dimensional accuracy is
not as critical.
Referring now to Figure 23 and 24, there is shown an arrangement which
allows resin to be supplied to a number of different mould assemblies in a
sequential manner. Figure 23 shows one such mould assembly 70 supporting a
lay-up 72 and located between the chamber walls 5 of two pressure chambers
1,2. The mould assembly 70 and pressure chambers 1,2 are all mounted in an
inclined position. A vacuum bag 30 is placed over the lay-up 72, and a resin
supply line 94 extends from a first resin container 92. Air pressure forces
the
resin through the resin supply line 94 into the space occupied by the lay-up
72.
As the pressure chambers 1,2 contain fluid, the pressure of the fluid which
increases with increasing depth assists in forcing the resin to the top of the
slope
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
43
of the mould assembly. The physical effect is a wave of resin moving up
through
the lay-up 72. Sufficient resin is supplied to the mould assembly 70 such that
there is an overflow of resin out therefrom. This overflow is collected by a
resin
drain line 98 which delivers this resin to a second resin container 92. A
vacuum
line 96 holds that resin container in a vacuum to help to draw up the resin.
The resin within the second resin container 92 can then supplied to
another mould assembly 70 as shown in Figure 24. This process can continue
sequentially through a number of mould assemblies.
Figures 25 to 28 show a number of different configuring arrangements for
locating and supporting component parts that need to be bonded to the
component being produced. Such components include reinforcement ribs,
attachment points, stringers and so 'on.
Referring initially to Figure 25, there is shown a mould section 121 upon
which is supported a composite or bonded metal lay-up 72. Located on top of
the
lay-up 72 are a series of parallel reinforcement ribs 123 that are to be
bonded to
the completed component. A vacuum film 30 is laid over both the lay-up 72 and
ribs 123 and a vacuum applied to provide initial compression of the lay-up and
to
help to hold the ribs 123 in place. A series of configured straps 125 can also
be
laid over the lay-up 72, ribs 123 and vacuum film 30 to locate and support the
ribs
123. Each strap 125 includes a series of "U" shaped bends 127 which can
engage the upstanding portion of the ribs 123. These straps 127 hold the ribs
123 in position while the elastically deformable chamber wall engages and
applies pressure to the complete assembly.
An alternative configuring arrangement is shown in Figure 26, this
arrangement including a bladder bag 131 supportable within a pressure chamber
housing 133. The bladder 131 when inflated within the housing provides the
chamber wall 132 for the pressure chamber housing 132. The bladder 132
includes a series of channels 135 When the chamber wall 135 is lowered over
the mould section 121 supporting the lay-up 72, reinforcement ribs 123 and
vacuum film 30, the channels 135 provide a space to accommodate the
upstanding portion of the ribs 123. This arrangement provides for improved
CA 02617076 2007-12-21
44
contact of the chamber waii 135 to the lay-up and ribs 123 during the
compression and curing or bonding stage.
The arrangement shown in Figure 26 utilizes a single bladder 131. It is
however also envisaged that the housing 133 accommodate more than one
bladder at the same time. Such an arrangement would allow very large
components to be produced where the use of a single bladder would be
impractical.
In a further embodiment of the configuring arrangement as shown in Figure
27, there is shown a relatively narrow in cross-section fluid flow bladder 137
made of elastically deformabie material which is shaped to conform to the lay-
up
72 supporting the ribs 123. The chamber wall 139 of the pressure chamber can
also be configured to conforrn with the general shape of the fluid flow
bladder
137. Fluid is circulated though the fluid flow bladder 137 during the
production
stage.
Figure 28 shows another embodiment of a configuring arrangement which
also utilizes a configured chamber wall 141 of a pressure chamber 133. As the
chamber wall is formed of elastically deformable materPaf, it can need to be
supported to retain its configured shape. Therefore, an internai support frame
145 can be provided within the pressure chamber 133, the support frame 145
having a configured support portion 147. When the pressure chamber 133 is
relieved of pressure, the chamber wall 141 can draw back against the support
portion 147 of the support frame 147 thereby holding the chamber in its
correct
general position.
In the Applicant's U.S. Patent No. 6,149,844, there is described a
composite or bonded metal production system. This production system could
also be adapted for semi-continuous production as shown in Figure 29. That
system utilizes a top pressure chamber 151 having an elastically deformabie
chamber wall, and a bottom chamber 153 supporting a resiliently mounted mould
section 155. Fluid at elevated temperature and pressure can be circulated
though both the pressure chambers 151, 153 during the production stage. The
fluid can be provided by a fluid circulation system similar to that described
in the
system shown in Figure 22.
CA 02617076 2007-12-21
The production system is adapted for semi-continuous production by
providing a plurality of bottom pressure chambers 153, each supported. on a
trolley157 to facilitate movement of the bottom pressure chambers 153. A
single
top pressure chamber 151 is mounted for vertical movement. Therefore, a
5 number of mould sections 155 of the bottom pressure chambers 153 can be
prepared to thereby accommodate a composite or bonded metal lay-up 159 while
another of the prepared bottom pressure chambers is located under the upper
pressure chamber 151. There is therefore no delays in the production process
due to the time taken to prepare the mould section for the production stage.
10 Figure 30 shows a variation of the semi-continuous production system of
Figure 29, the main difference being that the production system shown in
Figure
22 is used. That system only requires a top pressure chamber 151, the trolleys
157 supporting a rigidly mounted mould section.
In the adaptation of the abovedescribed production systems for mass
15 production, a series of stations can be used, each station supporting a
single
production system 159. To enable each of these stations to be supplied with
circulating fluid, the fluid circulation system described in the applicant's
U.S.
Patent No. 6,149,844 can be provided with ring mains 161. Each fluid reservoir
105,107,109 can be provided with a separate ring mains 161. A fluid supply
20 system 163 is provided at each station to circulation fluid though the
production
system 163 located at that station. The timing production sequence at each
station can be staggered so that there is no excessive withdraw of fluid at
any
one time from any of the fluid reservoirs. Because the fluid in each fluid
reservoir
is held at a particular constant temperature, this allows for the immediate
supply
25 of fluid at the required temperature by connecting to the appropriate fluid
reservoir. It is therefore not necessary to heat fluid because fluid at the
required
temperature is available at all times when using the fluid circulation system
according to the present invention. This also results in the flexibility of
the
manufacturing and curing phase of the process to commence a cure cycle at any
30 time, that is there is no fixed cure cycle times for start and finish that
the mould
must wait for.
CA 02617076 2007-12-21
WO 02/058916 PCT/AU02/00078
46
Figure 32 shows a reinforced mould section 180 located between two
pressure chamber walls 5. This mould section 180 includes an inner mould skin
181 providing the mould cavity, and an outer mould skin 182 on the opposing
side
of the mould skin 180. The thickness of the inner mould skin 181 is greater
than
the outer mould skin 182 to provide for dimensional accuracy.
Extending between the mould skins are a series of reinforcement fins 183.
These reinforcement fins 183 define box structures within the mould section
180.
The resultant mould section is more rigid and yet lighter than conventional
single
wall mould sections. Furthermore, fluid can be circulated at balanced pressure
or
slightly higher pressure to the pressure chambers through the box structures
of
the mould section 180 providing high heat transfer efficiencies for the mould
section 180. This is because the reinforcement fins 183 also acts as heating
and
cooling fins. The outer mould skin 182 can also be provided with outer
insulation
to reduce heat loss.
The method and system according to the present invention therefore
allows for the production of composite - and metal components in a semi-
continuous process. A major advantage of the production systems according to
the present invention is that they provide better utilization of the space in
a
production facility. For example, where autoclaves are used, space is required
to
transport and hold the moulds prior to using the autoclave. No such holding
space is required for production systems according to the present invention.
Modifications and variations as would be deemed obvious to the person
skilled in the art are included within the ambit of the present invention as
claimed
in the appended claims.
