Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to laminated panels
and to the manufacture of such panels, the panels being of
a type which are commonly used in the construction of truck
bodies and trailer bodies and for other outdoor applications
5 where they are exposed to weather conditions.
In the manufacture of laminated panels in which a
core of plywood has a layer of glass fiber reinforced resin
bonded on one or both sides of the core it is usually
necessary to apply a weather resistant facing layer to the
10 exterior side of the panel to protect the panel from
deterioration during use. The facing layer usually consists
of a film of weather resistant fluoroplastics material, most
commonly a film of polyvinylfluoride such as that sold by
the Dupont Corporation under the trade mark "TEDLAR", and
15 which has been treated for adherability on one or both
sides. One of the difficulties associated with the
manufacture of such panels is that the fluoroplastics film,
which is about 1.5 mils thick, tends to wrinkle and crease
while it is being applied to the uncured resin layer, and
removal of such minor flaws from the film prior to curing
20 is both difficult and time consuming.
Our Canadian Patent No. 1,166,137 dated April 24,
1984 relates to an improved method of applying the film
whereby this difficulty is overcome.
However, when such panels are to be used in the
construction of truck and trailer bodies, regardless of the
25 nature of the exterior facing layer, it is often necessary
to protect the interior sides of the panels from damage by
handling during construction of the bodies and from damage
by loading and unloading when the truck and trailer bodies
are in use. The forks of fork lift trucks are a common
cause of such damage.
To deal with the problem a raised scuff is often
fastened to the interior of the panel, by screws, staples
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or adhesive, the scuff extending parallel to the bottom
edge of the panel for the whole length thereof. The bottom
edge of the scuff, which is typically about 24 inches wide
is spaced from the bottom edge of the panel by a distance
5 of one to eight inches. The current practice is to
prefabricate the scuffs and attach them to the panels, when
required, at the required positions. Apart from the
additional labour required, this practice has the dis-
advantage that the scuffs can easily become detached or
10 loosened by impact, when struck by the forks of a fork lift
truck, say; it also has a disadvantage which is even more
serious in certain applications where hygiene is important,
namely that the corners between the scuffs and the panels
tend to harbour dirt and perishable fragments, and are not
15 easily cleaned.
The present invention provides an improved laminated
panel construction which overcomes these disadvantages.
The invention also provides a process for manufacturing the
improved panel.
According to one aspect of the present invention
there is provided a laminated panel having at least one
straight longitudinal edge and a raised scuff extending
parallel to said edge on one side of the panel for the
whole length thereof, the panel comprising a laminar core,
25 a first unitary covering of resin-impregnated fibrous
material laminated in situ to said one side of the core,
a second unitary covering of resin-impregnated fibrous
material laminated in situ to the other side oE the core,
said first covering comprislng a sheet of said resin-
30 impregnated fibrous material covering the entire area ofsaid one side of the core and an elongate strip of said
resin-impregnated fibrous material superposed thereon and
molded in situ onto the sheet to form an integral
thickened region of the covering defining said scuff, the
35 longitudinal edges of the strip being bevelled and merging
into said sheet.
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In cases where it is required, a wrinkle-free facing
layer of weather resistant fluoroplastics material may be
laminated onto the second (i.e. exterior) unitary covering
of resin-impregnated fibrous material.
According to another aspect of the invention, a
process for manufacturing the panel comprises assembling
in superposed relationship, on a flat hard shaping surface
providing a parallel-sided channel having bevelled edges,
a laminar core having at least one straight longitudinal
edge, the core being positioned so as to extend across said
channel with said straight edge lying parallel to the
bevelled edges at a predetermined distance therefrom, a
first sheet of resin-impregnated fibrous material inter-
posed between the core and said surface and covering the
entire area of one side of the core, a second sheet of
resin-impregnated fibrous material covering the entire area
of the other side of the core, and at least one strip of
resin-impregnated fibrous material interposed between the
first sheet and said shaping surface, said at least one
strip being of the same width as said channel and being
positioned so as to extend along the channel to fill same,
positioning the assembly horizontally, with said second
sheet uppermost, in a press having upper and lower platens
while maintaining said superposed relationship on the
shaping surface, closing the press, and laminating the
assembly under heat and pressure.
In cases where an exterior facing layer o~ fluoro-
plastics material is required, this may be applied by the
method described in the above-mentioned Patent No.
1,166,137, using the apparatus disclosed therein, the
assembly including the fluoroplastics film being laminated
under heat and pressure in the one operation.
A laminated panel in accordance with the invention,
and a process. for making the panel, will now be described,
by way of example, with reference to the accompanying
drawings.
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In the accompanying drawings:
Figure 1 illustrates the structure of a laminated
panel according to the invention;
Figure 2 illustrates the assembly of the panel
5 layers on a caul plate;
Figure 3 illustrates a detail of the caul plate;
Figure 4 is a side elevational view of the caul
plate; and
Figures 5 and 6 illustrate two stages in the
manufacturing process.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The finished product is shown in Figure 1. The
product is a laminated panel which in the present example
is rectangular, but in any event must have at least one
straight iongitudinal edge 10, this being the bottom edge
of the panel~ The dimensions of the panel are typically
10 feet x 46 feet. The laminated assembly comprises a
laminar core of plywood 11 having a first unitary, i.e.
continuous, covering of resin-impregnated fibrous material
12 laminated to one side of the core 11 and a second
unitary covering of resin-impregnated fibrous material 13
laminated to the other side of the core. The coverings
conform to the rectangular shape and dimensions of the
core, and the ma~erial is preferably a polyester-
impregnated woven glass fiber material of a type commonlyused in such applications.
The first covering 12 has an integral raised
surface portion 14 which extends for the full length of the
panel parallel to the bottom edge 10, and forms the raised
scuff on the interior side of the panel. This raised
portion 14 is in fact a thickened portion of the first
covering 12, being molded in situ therewith so that the
material of the raised portion and of the rest of the
covering are homogeneous without an interface. A
characteristic feature of the raised portion 14 is that it
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has a flat surface with parallel bevelled edges lS by which
the flat surface merges smoothly into panel surface.
In the illustrated embodiment a wrinkle-free facing
layer 16 of fluoroplastics material is laminated in situ
onto the second covering 13 to form the exterior surface
of the panel.
Figure 2 shows the assembly of the layers to be
laminated to form the panel of Figure 1, the layers being
assembled on a caul plate 17 which provides a hard flat
shaping surface 18. Details of the caul plate 17 are
shown in Figures 3 and 4.
The caul plate 17 is a flat rectangular steel plate
adapted to be mounted on the lower platen of a press. The
shaping surface 18 is characterized by a parallel-sided
shallow channel 19 having an embossed bottom surface 20
and bevelled edges 21. One longitudinal edge 22 of the
caul plate is spaced from the nearer of the channel edges
21, which run parallel to it, by about eight inches, and
a row of raised stops 23 (only one of which is shown in
Figure 4) are fixed along the caul plate adjacent its edge
22. These stops 23 are used to locate the plywood core 11
with respect to the channel 19 during the assembling
process. However, the location of the CGre with respect
to the channel can be adjusted by appropriate selection of
spacers 24, 25 and 26 of different sizes, a spacer 24
being shown in its operative position in Figure 4.
The layers are assembled in the following manner.
First, a release film 27 o~ MYhAR ttrade mark) is
laid upon the shaping surEace 18 of the caul plate to
facilitate removal of the assembly after the lamination
process. Then the various components to be laminated are
assembled in superposed relationship on top of the release
film 27 in the following sequence: one or more strips 28,
29 of the resin-impregnated fibrous material having the
same width as the channel 19, a first rectangular sheet 30
of the resin-impregnated fibrous material, at least one
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further stri.p 31 of the resin-impregnated fibrous material,
the plywood core 11, a second sheet 32 of the resin-
impregnated fibrous material, and a film of fluoroplastics
material 33. The components are suitably positioned with
respect to the channel 19 by means of the stops 23
(Figure 4), so that the edges which will form the bottom
edge of the panel abut against the stops. The strips 28,
29 and 31 are superimposed in registration with the
channel 19. Although three such strips are shown in
Figure 2, the number of strips will be chosen to suit the
particular manufacturing requirement and must be such that
the fibrous material will fill the channel 19 when the
assembled layers are pressed onto the caul plate. The
assembly is next placed on the lower platen of a laminating
press while maintaining the superposed relationship of the
components on the surface of the caul plate; the press is
closed, and the assembly is laminated under heat and
pressure. Thereafter the press is opened and the laminated
assembly is removed from the caul plate, the edges of the
panel being trimmed.
The first sheet of fibrous material 30 and the
strips 28, 29 and 31 are thus molded together in situ to
form the first unitary covering 12 (Figure 1) having the
integral raised portion 14. The second sheet 32 is
similarly laminated in situ onto the upper surface of the
core 11 to form the second unitary covering 13 (Figure 1),
the film 33 being laminated onto the latter to form the
facing layer 16.
Referring now to Figures 5 and 6, the caul plate
17 on which the laminate components are assembled is
mounted horizontally on the lower platen 34 of the
laminating press, the shaping surface 18 of the caul
plate being uppermost. The platen 34 is equipped with
wheels 35, whereby it can be displaced horizontally
from its operative position beneath the upper platen 36,
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to a second position (Figure 6) where the caul plate
is exposed to permit assembly of the laminate components
thereon, and whereby it can be reinserted to the
operative position in preparation for the laminating
process. The upper platen 36 of the press is adapted
to be heated by hot water and steam, or electrically,
to a temperature in the range 170-210F., and is adapted
to be raised and lowered by hydraulic rams 37, thereby
to be pressed against the lower platen 34 to a pressure
of about 30 p.s.i. The lower platen is adapted to be
heated to a temperature of about 120F.
In order to apply the film 33 to the assembly,
the film is initially supported between longitudinally
spaced support rollers 38, 39 attached to the ends of
the upper platen 36, and is stretched longitudinally
and laterally, in the manner described in the above-
identified patent, so as to lie in a substantially
horizontal plane spaced from the lower face of the upper
platen. After the lower platen 34 has been inserted
to its operative position, with the caul plate and
assembled layers thereon, the upper platen 36 is lowered
to bring the film into contact with the uppermost (second)
resin-impregnated fibrous sheet 32 while maintaining
the spacing of the film from the lower face of the platen.
The press is then closed and the assembly is laminated
under heat and pressure.
However, the present invention is also applicable
to cases in which a wrinkle-free facirlg layer oE fluoro~
plastics material is not re~luired. In such cases a
facing layer may simply be preassembled with the other
laminate components, or dispensed with in some cases.
In the present example the core is of 3/4 inch
7-ply Douglas Fir plywood measuring 10 x 46 feet. The
material of the coverings 12, 13 is preferably a
polyester-resin-impregnated woven glass fiber material.
The glass fiber is a Type 702 24 ounce/yard woven roving
impregnated with the resin mixed with a suitable catalyst.
The resin system typically has the following composition:
Ingredients Parts
2T 1008 100
CaCO3 50
Titanox 2
MEK 0.5
With this system the assembled components are
laminated together at the temperature of the press under
a pressure of 30 p.s.i., and the laminated panel is
then cured in the press for a period from 7 to 25 minutes,
preferably 15 minutes.
As will be understood by the man skilled in the
art, other resin systems of the thermosetting type may
alternatively be used, for example vinyl, epoxy and
phenolic resins.
The product is characterized in that the interior
(first) covering of the panel is homogeneous throughout,
the raised scuff being molded integrally with it, and
having bevelled edges which merge into the surface of
the panel so as to eliminate corners and crevices which
would collect dirt and contaminants difficult to remove.
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