Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION:
Wet Out Box for Fibre Wetting and Method of Use of the Same
FIELD OF THE INVENTION
The present invention relates to a wet out box used for fibre wetting during
filament
winding and a method of use of the same.
BACKGROUND OF THE INVENTION
Filament winding is a process in which wet resin is applied to filaments and
the
filaments are wound onto a mould. The resin sets and binds the filaments
together, thereby
forming the composite material. The wetting out of fibre glass is an integral
part of the
filament winding process because the physical properties of the final
composite material
are dependant, in part, upon the degree of fibre wet out achieved.
The present industry standard for wetting fibres utilizes a resin bath. Fibres
are
either pulled directly through the bath or passed over a rotating drum that
sits partially
submerged in a resin bath. In the latter process, resin coats the surface of
the drum and is
then transferred to the fibres as they contact the drum. In both processes the
fibres are
subsequently wiped of excess resin as they travel to a mandrel upon which they
are wound
with the excess resin being recycled.
SUMMARY OF THE INVENTION
According to a one aspect of the present invention there is provided a wet out
box
which includes a container made from two abutting halves which are separable.
A first seal
face is carried by a first one of the two abutting halves. A second seal face
is carried by a
second one of the two abutting halves. Means are provided to maintain the two
abutting
halves in abutting relation with the first seal face engaging the second seal
face to create a
container that maintains liquid resin within the container.
According to another aspect of the present invention, there is provided a
method of
wetting fibres with resin using the wet out box described above.
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BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more apparent from the
following description in which reference is made to the appended drawings, the
drawings are
for the purpose of illustration only and are not intended to in any way limit
the scope of the
invention to the particular embodiment or embodiments shown, wherein:
FIG. 1 is a perspective view of wet out box constructed in accordance with the
teachings of the present invention.
FIG. 2 is an exploded perspective view of the wet out box illustrated in FIG.
1, with
the two halves separated.
FIG. 3 is an exploded end elevation view, in section, of the wet out box
illustrated in
FIG.1 showing the height of the wet out box in the vertical direction and the
depth of the wet
out box in the horizontal direction.
FIG. 4 is an end elevation view, in section, of the wet out box illustrated in
FIG. 1.
FIG. 5 is a front elevation view of an interior face of one of the halves
illustrated in
FIG. 1 showing the height of the wet out box in the vertical direction and the
width of the wet
out box in the horizontal direction.
FIG. 6 is an end elevation view, in section, showing fibres passing through
the wet
out box illustrated in FIG. 1.
FIG. 7 is a perspective view of the wet out box illustrated in FIG. 1, with
one
configuration of the associated clamping assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment, a wet out box generally identified by reference
numeral
10, will now be described with reference to FIG. 1 through 7.
Structure and Relationship of Parts:
Referring to FIG. 1, wet out box 10 includes a container 12 made from two
abutting
halves: a first half 14 and a second half 16. Referring to FIG. 2, halves 14
and 16 are
separable. Referring to FIG. 6, when halves 14 and 16 are pressed together in
abutting
relation they form container 12, which is intended to contain a liquid resin
100. Referring to
FIG. 4, container 12 has opposed sides 18 and 20 and a bottom 22. In order to
avoid leakage
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between halves 14 and 16, a first seal face 24 is carried by first half 14 and
a second seal face
26 is carried by second half 16. Referring to FIG. 4 and 6, container 12
defines a reservoir 36
and a passageway 105. The passageway consists of an upper inlet 28 through
which fibres
102 to be wetted enter and a lower outlet 30 in bottom 22 through fibres 102
to be wetted exit.
A wet out path that fibres 102 follow from upper inlet 28 to lower outlet 30
is indicated by
arrows 104. Wet out path 104 is more vertical than horizontal. As illustrated,
it is shown as
being substantially vertical, but it need not be. It could have an angular
component. Wet out
path 104 is substantially linear, although it may weave around over and under
bars 32, as will
hereinafter be further described. Refening to FIG. 5, each of first half 14
and second half 16
of container 12 is made from a plate 34 of material that is machined to form
half of a
reservoir 36. Peripheral slots 38 are provided for insertion of either first
seal face or
second seal face. The peripheral slots define an edge seal region 40 and a
wiping seal
region 42. The seals are extruded profiles and are replaceable in order to
optimize the
performance of the wet out box. Depending on the design of the box, there are
one or
more types of seals used in the wet out box. Regardless, the seals serve the
same purpose.
Referring to FIG. 6, the seals act as a spacer between halves 14 and 16 of wet
out box 10
and prevent fibres 102 from contacting the inside opposing faces of the
container. The
side seals do not contact fibres 102. The wiper seal across bottom 22 of wet
out box 10
contacts the fibres and is the critical surface for resin impregnation. The
thickness of the
seal in conjunction with the depth of slot 38 determine, in part, the volume
of reservoir 36.
These seals can be made from a variety of elastomeric materials such as butyl
rubber,
nitrile, vinyl, or other such materials and can therefore be tailored to meet
the parameters
required to optimize production cycles and fibre wet out. The profiles are
extruded so that
the seals fit into slots 38. There may or may not be provided slots 44 to
accommodate
insertion of over and under bars 32, depending on the application. Over and
under bars 32
are made from extruded elastomers, such as butyl rubber, vinyl, nitrile, or
any other
suitable elastomeric material. Referring to FIG. 4 and 6, when two halves 14
and 16 are
clamped together reservoir 36 and passageway 105 are formed. Wet out box 10
can be
machined from a number of materials, such as wood, plastic or metal. Wet out
box 10
may or may not be coated with a non-stick material such as Teflon or Needox in
order to
facilitate cleaning. Referring to FIG. 5, interior surface 46 of each plate 34
may or may
not be treated with a non-stick coating, designated by reference numera148.
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Refen-ing to FIG. 1, the width of wet out box 10 is relative to the number of
fibres
used in the process. The spacing between fibres 102 passing through reservoir
36 is
sufficient to allow for complete wet out of the fibres. Wet out box 10 can be
designed to
accommodate a single roving or multiple rovings, dependant on the application.
Referring to FIG. 6, the space between halves 14 and 16 of container 12
determines in part the depth of the wet out box and is designed to provide
reservoir 36
with sufficient volume and also provide clearance between fibres 102 and the
interior
opposed sides 18 and 20 of passageway 105.
Referring to FIG. 6, the height of wet out box 10 in part determines the
volume of
container 12. The height of wet out box 10 also determines the residence time
of the
fibres 102 passing through container 12 relative to the speed of the fibres.
The height of
the resin in container 12 is defined by the distance from wiping seal at lower
outlet 30 to
the top of the resin in reservoir 36. The residence time is a function of the
velocity of
fibres 102 passing through container 12 and the height of the resin in
container 12. Wet
out box 10 can be designed to accommodate a variety of residence times based
on the
speed the application requires in order to completely wet out the fibres.
There are a various ways in which pressure may be applied to maintain two
abutting halves 14 and 16 in abutting relation which can be manual or
automated in
nature. Referring to FIG. 7, a manual clamping assembly, generally identified
by
reference numeral 50 has been illustrated. Clamping assembly 50 has a series
of clamps
52 which maintain abutting halves 14 and 15 in abutting relation. Each of
clamps 52 has a
rotating handle 54. Rotation of handle 54 serves to selectively vary pressure
exerted by one
of clamps 52. Referring to FIG. 6, this adjustment is made to adjust the
sealing engagement
between first seal face 24 and second seal face 26 to prevent resin leakage
while maintaining
adequate wet out of fibres 102 with liquid resin 100.
Operation:
The use and operation of wet out box 10 will now be described with reference
to
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FIG. 1 through 7.
Referring to FIG. 6, wet out box 10 is designed for use in a filament winding
process. It is preferred that a vertically downward wet out path 104 be
traveled by fibres
5 102 during wet out. The process is characterized by low resin volumes and
low residence
time. First seal face 24 and second seal face 26 are provided by removable
disposable
seals, which form a seal that acts to impregnate fibres 102 with resin as
fibres 102 pass
between them. Two halves 14 and 16 are pressed together in abutting relation
to create
container 12 with reservoir 36.
Wet out box 10 is mounted on filament winding equipment (not shown) so that
fibres 102 passing through wet out box 10 can be directed to the winding
process
immediately after being wet out. The fibres used may be E-glass, S-glass,
carbon fibres,
basalt fibres, aramid fibres, or any other fibre associated with composite
reinforcing
material.
Referring to FIG. 1, the amount of resin that remains on fibres 102 after wet
out is
controlled by a series of pressure points, indicated by arrows 108, directed
against the face
of wet out box 10 to apply localized pressure onto the seal formed by the
engagement
between first seal face 24 and second seal face 26. This pressure can be
adjusted during
production runs in order to eliminate leakage, control wet out, and to
optimize the resin to
fibre ratio of the final composite material. Referring to FIG. 7, one manner
of applying
pressure is illustrated; that being through a clamping system 50.
Referring to FIG. 6, the low volume and short residence time of liquid resin
100
held in reservoir 36 and passageway 105 prevents the polymerisation of liquid
resin 100
prior to liquid resin 100 being transferred out of wet out box 10 by fibres
102 passing
through wet out box 10. The residence time of the resin in wet out box has
been
calculated to be approximately 35 seconds during full scale production. This
configuration also allows for the complete evacuation of liquid resin 100
through lower
outlet 30 at bottom 22 in order to empty wet out box 10 rapidly. Referring to
FIG. 2, two
halves 14 and 16 of wet out box 10 are advantageously designed to be easily
separated by
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removing the force applied in order to dismantle wet out box 10. Referring to
FIG. 6, first
seal face 24 and second seal face 26 act to prevent the loss of liquid resin
100 and acts to
force air from fibres 102 and force resin into fibres 102. Referring to FIG.
5, these seals
are easily and advantageously removable from slots 38 in plates 34 out of
which first half
14 and second half 16 are formed.
Referring to FIG. 6, where over and under bars 32 are used, the contact
between
over under bars 32 and fibres 102 passing over the surface of over and under
bars 32 acts
to force air from fibres 102 and force liquid resin 100 into fibres 102.
Referring to FIG. 5,
over and under bars 32 are easily and advantageously removable from slots 40
in plates 34
out of which first half 14 and second half 16 are made.
Wet out box 10 should be designed to suit the process with which it is to be
used.
One of the key factors that effects the structure of wet out box 10 is the
intended speed of
the filament winding process. Once the speed of the process is known, wet out
box 10 is
made with sufficient height to allow a thorough wet out of fibres passing
through wet out
box at the intended speed. Reservoir 36 is made of a sufficient size to
continuously supply
liquid resin 100 required for wet out at the intended speed. Once wet out box
10 is built,
installed and operational, fine adjustments are made by altering the force
applied at critical
pressure points that hold first half 14 and second half 16 in abutting
relation to apply
pressure upon first seal face 24 and second seal face 26. Referring to FIG. 7,
one way of
making such adjustments is through a manual clamping system 50. An automated
system
could also be used.
Wet out path 104 could be made horizontal, but there are significant
advantages to
providing a vertical wet out path. When wet out path 104 through wet out box
10 is more
vertical than horizontal, with fibres 102 exiting through bottom 22, clean up
is simplified.
Gravity is used to drain liquid resin 100 from wet out box 10. Referring to
FIG. 2, the
two halves 14 and 16 are then separated for internal cleaning. Depending on
the material
used to fabricate the halves 14 and 16, a non-stick coating may be utilized to
prevent the
resin from sticking to wet out box 10.
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Although this method was initially designed to be used with polyurethane, it
has
been shown that polyester, vinyl ester, epoxy or any other resin acting as a
composite
matrix can be used with this method.
Examples:
The first example involves a single fibre being wet out at low speed. For the
purposes of research, a narrow unit was constructed to wet out a single roving
in order to
wind sample rings for testing. Fibre was passed through this box at a rate of
20 feet per
minute. The total width of the box was 3 inches, with the reservoir being 1
inch wide. The
length of the box (in the direction of glass travel) was 7 inches. The seals
used on this box
were 1 inch wide strips of butyl rubber and were attached to the body of the
box with glue.
The material used to make this box was 1 inch thick multi-directional fibre
(MDF) board.
The wiping seal was created by an angled slot across the exit of the box such
that the face
of the wiping seal started flush with the inside surface of the box, and rose
up to be flush
with the height of the side seals. Pressure on the seal to control the degree
of wiping was
controlled by a simple C-clamping.
The second example involves 24 fibres being wet out at medium speed. For the
purposes of proto typing, a medium width unit was constructed to wet out
twenty four
rovings in order to wind conveyor rollers. Fibre was passed through this box
at a rate of 60
feet per minute. The total width of the box was 10 inches, with the reservoir
being 8 inch
wide. The length of the box (in the direction of glass travel) was 12 inches.
The seals used
on this box were of two designs. The side seals were 1/4 by 3/8 inch extruded
vinyl. The
wiper seal was a I and 1/2 inch wide tapered vinyl extrusion that was 3/16
inch at the
narrow end rising to 3/8 at the seal end. The seals were inserted into slots
machined into
the body of the box. The material used to make this box was 1 inch thick ultra
high
molecular weight (UHMW) polyethylene. Pressure on the seal to control the
degree of
wiping was controlled by a series of adjustable grips.
The third example involves two wet out boxes in parallel, each wetting out 96
fibres at high speed for a total of 192 rovings total. For the purposes of
production, a pair
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of wide boxes were constructed to wet out at ninety six rovings each in order
to wind
utility poles. The dual boxes also incorporated over and under bars to
facilitate fibre wet
out. Fibre was passed through this box at a rate of 200 feet per minute. The
total width of
the box was 24 inches, with the reservoir being 22 inch wide. The length of
the box (in the
direction of glass travel) was 12 inches. The seal used on this box was a one
piece 1/2 inch
diameter round nitrile extrusion. The seal was inserted into a single slot
that ran down the
edge of the inside of each of the halves of the box, across the bottom, and
back up the
inside edge of the box. The material used to make this box was 1 inch thick
ultra high
molecular weight (UHMW) polyethylene. Over/under bars were used to facilitate
wetting
of the fibre as the fibre passed through the reservoir. The over/under bars
were made of
the same nitrile extrusion as the seals. The over/under bars were located in
slots cut into
the body of the box and running perpendicular to the direction of the travel
of the glass.
Pressure on the seal to control the degree of wiping was controlled by an
automated
hydraulic clamping system.
Additional Benefits:
The seals in the wiping section of the box create a zone of high pressure
within the
body of the resin at the entrance to the seal area which increases the
penetration of the resin
into the glass fibres as the fibres pass between the seals. The seals in the
wiping section also
allow the wet out box to impregnate glass fibres with low viscosity resins.
The wet out box
eliminates resin loss by having the wiping of the glass fibres occur at a
point on the wiping
seal that is internal to the wet out box. The wet out box eliminates the need
to recycle the
resin, as excess resin is prevented from leaving the box. The width of the
container can be
specified to accommodate any number of glass fibres. The height of the
container can be
specified to increase or decrease the time it takes for the glass to pass
through the container.
The volume of the container is minimized to allow for rapid evacuation of the
resin from the
container as resin is removed from the container by the fibres passing through
and carrying
the resin from the container and thereby minimizing the residence time of the
resin in the
container. The volume of the container is minimized to allow for minimal loss
of resin if the
container is opened while resin is present in the container.
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Cautionary warnings:
It would be counter productive to orient the box any way other than vertically
(unless out of necessity it was being fit into a confined space). The vertical
orientation
allows for purged air to rise freely to the surface. It also allows for new
resin to enter the
top, with older resin leaving at the bottom. If the box is tipped on its side,
the resin would
run out unless some type of extra reservoir is incorporated. The vertical
orientation also
allows for the box to run completely dry (the small volume of the reservoir
allows this to
happen quickly) to facilitate cleaning. Horizontal boxes have a "floor" on
which the resin
sits and has to be drained. The box could be tipped to the angle at which the
resin begins
to run from the reservoir. It could lie flat and have an elevated reservoir.
This would not
affect the way the seal works. However, if the air was unable to exit the box
by bubbling
up, it could end up exiting through the seal and defeating the wet out
process. As long as
there is a method of keeping the resin in the box, any angle would suffice,
albeit less
efficiently.
In this patent document, the word "comprising" is used in its non-limiting
sense to
mean that items following the word are included, but items not specifically
mentioned are not
excluded. A reference to an element by the indefinite article "a" does not
exclude the
possibility that more than one of the element is present, unless the context
clearly requires that
there be one and only one of the elements.
It will be apparent to one skilled in the art that modifications may be made
to the
illustrated embodiment without departing from the spirit and scope of the
invention as
hereinafter defined in the Claims.
