U.S. patent application number 09/812093 was filed with the patent office on 2001-08-09 for foamed core composite plate for use in trailer walls and doors.
This patent application is currently assigned to WABASH TECHNOLOGY CORPORATION. Invention is credited to Ehrlich, Donald J., Ehrlich, Rodney P., LeWallen, Wilfred E..
Application Number | 20010011832 09/812093 |
Document ID | / |
Family ID | 25477671 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010011832 |
Kind Code |
A1 |
Ehrlich, Donald J. ; et
al. |
August 9, 2001 |
Foamed core composite plate for use in trailer walls and doors
Abstract
A novel composite plate is used to form a wall or a door of a
vehicle, such as a trailer or van. Each composite plate used in the
trailer is formed from a pair of metal skins, such as aluminum or
steel, having a foamed thermal plastic core member sandwiched
therebetween. The skins are bonded to the core member by a known
flexible adhesive. The foamed thermal plastic core member is
resilient and may be made from foamed high density or foamed low
density thermal plastic. The foaming of the core member in the
present invention reduces the weight of the composite plate versus
prior art solid plastic core composite plates and provides for an
increased the peel strength of the composite plate versus prior art
solid plastic core composite plates. Furthermore, foaming of the
thermal plastic core member in the present invention reduces the
shear stress of the skin to core bond layer so as to reduce the
potential of delamination of the metal skins from the thermal
plastic core member under changing temperatures which has been
found to be a problem with solid core composite plates.
Inventors: |
Ehrlich, Donald J.;
(Lafayette, IN) ; Ehrlich, Rodney P.; (Monticello,
IN) ; LeWallen, Wilfred E.; (West Lafayette,
IN) |
Correspondence
Address: |
Trexler, Bushnell, Giangiorgi,
Blackstone & Marr, Ltd.
105 West Adams Street, Suite 3600
Chicago
IL
60603
US
|
Assignee: |
WABASH TECHNOLOGY
CORPORATION
ARLINGTON HEIGHTS
IL
60005-1430
|
Family ID: |
25477671 |
Appl. No.: |
09/812093 |
Filed: |
March 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09812093 |
Mar 19, 2001 |
|
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|
08942172 |
Oct 1, 1997 |
|
|
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5883692 |
|
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60057722 |
Aug 28, 1997 |
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Current U.S.
Class: |
296/186.1 ;
296/191; 296/901.01 |
Current CPC
Class: |
A61B 3/024 20130101;
B29C 44/326 20130101; B29C 44/321 20161101; E04C 2/292
20130101 |
Class at
Publication: |
296/181 ;
296/191; 296/901 |
International
Class: |
B62D 033/04 |
Claims
The invention claimed is:
1. A trailer comprising: a floor and at least one upstanding member
extending upwardly from said floor, said upstanding member
including a pair of skins having a foamed thermal plastic core
member sandwiched therebetween.
2. A trailer as defined in claim 1, wherein said foamed thermal
plastic core member is resilient.
3. A trailer as defined in claim 1, wherein said foamed thermal
plastic core member is made from foamed high density thermal
plastic.
4. A trailer as defined in claim 3, wherein said foamed high
density thermal plastic is foamed high density polyethylene or high
density polypropylene.
5. A trailer as defined in claim 1, wherein said foamed plastic
core member is made from foamed low thermal plastic.
6. A trailer as defined in claim 5, wherein said foamed low density
thermal plastic is foamed low density polyethylene or low density
polypropylene.
7. A trailer as defined in claim 1, wherein said upstanding member
is a side wall or a front wall of said trailer.
8. A trailer as defined in claim 1, wherein said upstanding member
is a door of said trailer.
9. A trailer as defined in claim 1, wherein said skins are formed
from metal.
10. A trailer as defined in claim 1, wherein said skins are bonded
to said core member by a flexible adhesive.
11. A trailer as defined in claim 1, wherein said upstanding member
is formed by mixing thermal plastic resin pellets and gas pellets;
applying heat to said mixed pellets and extruding said heated
mixture.
12. A trailer as defined in claim 1, wherein said upstanding member
is formed by applying heat to thermal plastic resin pellets in a
heating chamber; injecting nitrogen into said heating chamber,
thereby forming a foamed mixture; and extruding said foamed mixture
from said heating chamber.
13. A trailer as defined in claim 1, wherein said upstanding member
is formed by mixing thermal plastic resin pellets and gas pellets;
applying heat to said mixed pellets in a heating chamber; injecting
nitrogen into said heating chamber, thereby forming a foamed
mixture; and extruding said foamed mixture from said heating
chamber.
14. A trailer as defined in claim 1, wherein said thermal plastic
core member has a thickness of one half of an inch or less.
15. A method of forming a wall or a door of a trailer comprising
the steps of: mixing thermal plastic resin pellets and gas pellets
together; applying heat to said mixed pellets; extruding said
heated mixture into a core member; and bonding skins to opposite
sides of said core member.
16. A method as defined in claim 15, further including the step of
applying a flexible adhesive to inner surfaces of said skins or to
opposite sides of said core member prior to bonding said skins to
said opposite sides of said core member.
17. A method of forming a wall or a door of a trailer comprising
the steps of: applying heat to thermal plastic resin pellets in a
heating chamber; injecting nitrogen into said heating chamber,
thereby forming a foamed mixture; extruding said foamed mixture
from said heating chamber into a core member; and bonding skins to
opposite sides of said core member.
18. A method as defined in claim 17, further including the step of
applying a flexible adhesive to inner surfaces of said skins or to
opposite sides of said core member prior to bonding said skins to
said opposite sides of said core member.
19. A method of forming a wall or a door of a trailer comprising
the steps of: mixing thermal plastic resin pellets and gas pellets
together; applying heat to said mixed pellets in a heating chamber;
injecting nitrogen into said heating chamber, thereby forming a
foamed mixture; extruding said foamed mixture from said heating
chamber into a core member; and bonding skins to opposite sides of
said core member.
20. A method as defined in claim 19, further including the step of
applying a flexible adhesive to inner surfaces of said skins or to
opposite sides of said core member prior to bonding said skins to
said opposite sides of said core member.
21. A wall for use in a trailer comprising: a member including a
pair of skins having a foamed thermal plastic core member
sandwiched therebetween.
22. A wall as defined in claim 21, wherein said foamed thermal
plastic core member is made from foamed high density thermal
plastic.
23. A wall as defined in claim 22, wherein said foamed high density
thermal plastic is foamed high density polyethylene or high density
polypropylene.
24. A wall as defined in claim 21, wherein said foamed thermal
plastic core member is made from foamed low density thermal
plastic.
25. A wall as defined in claim 24, wherein said foamed low density
thermal plastic is foamed low density polyethylene or low density
polypropylene.
26. A wall as defined in claim 21, wherein said skins are formed
from metal.
27. A wall as defined in claim 21, wherein said skins are bonded to
said core member by a flexible adhesive.
28. A wall as defined in claim 21, wherein said thermal plastic
core member has a thickness of one half of an inch or less.
29. A door for use in a trailer comprising: a member including a
pair of skins having a foamed thermal plastic core member
sandwiched therebetween.
30. A door as defined in claim 29, wherein said foamed thermal
plastic core member is made from foamed high density thermal
plastic.
31. A door as defined in claim 30, wherein said foamed high density
thermal plastic is foamed high density polyethylene or high density
polypropylene.
32. A door as defined in claim 29, wherein said foamed thermal
plastic core member is made from foamed low density thermal
plastic.
33. A door as defined in claim 32, wherein said foamed low density
thermal plastic is foamed low density polyethylene or low density
polypropylene.
34. A door as defined in claim 29, wherein said skins are formed
from metal.
35. A door as defined in claim 29, wherein said skins are bonded to
said core member by a flexible adhesive.
36. A door as defined in claim 1, wherein said thermal plastic core
member has a thickness of one half of an inch or less.
Description
[0001] This application claims the priority of provisional
application Ser. No. 60/057,722, filed on Aug. 28, 1997, entitled
"Foamed Core Composite Plate For Use In Trailer Walls And
Doors".
BACKGROUND OF THE INVENTION
[0002] This invention is generally directed to a novel composite
plate for a trailer wall construction or a trailer door
construction. More particularly, the invention contemplates a novel
composite plate that has a foamed thermal plastic core which
provides a variety of advantages over prior art solid core
composite plates.
[0003] Composite plates having solid plastic cores for use in
forming trailer walls or doors are known in the art. Such composite
plates are formed from a pair of metal skins, formed of aluminum or
steel, having a solid plastic core member, formed of polyethylene
or polypropylene, sandwiched therebetween. The use of a solid
plastic core member in a composite plate has worked reliably in the
prior art, however, several disadvantages have been found.
[0004] Solid core composite plates tend to have low peel strength.
That is, the metal skins peel away from the plastic core with small
force. Furthermore, with the prior art solid core member, a high
shear stress is obtained as the plastic core material changes
temperature and if the shear stress gets too high, then the metal
skins can delaminate from the solid plastic core member.
[0005] The present invention provides a novel composite plate
having a foamed thermal plastic core member that is used in a
trailer wall construction or a trailer door construction which
overcomes the disadvantages of using a prior art solid plastic core
member in a composite plate. Other features and advantages will
become apparent upon a reading of the objects and description taken
in combination with a study of the drawings.
OBJECTS AND SUMMARY OF THE INVENTION
[0006] A general object of the present invention is to provide a
novel composite plate having a foamed thermal plastic core member
which forms a wall or a door of a vehicle, such as a trailer.
[0007] An object of the present invention is to provide a novel
composite plate for a trailer wall or door construction having a
foamed thermal plastic core member which reduces the weight of the
plate versus prior art solid core composite plates.
[0008] Another object of the present invention is to provide a
novel composite plate for a trailer wall or door construction
having a foamed thermal plastic core member which increases the
peel strength of the plate versus prior art solid core composite
plates.
[0009] A further object of the present invention is to provide a
composite plate for a trailer wall or door construction which
reduces the shear stress of the skin to core bond layer so as to
reduce the potential of delamination of the metal skins from the
thermal plastic core member under changing temperatures.
[0010] Briefly, and in accordance with the foregoing, the present
invention discloses a novel composite plate which is used to form a
wall or a door of a vehicle, such as a trailer or van. Each
composite plate used in the trailer is formed from a pair of metal
skins, such as aluminum or steel, having a foamed thermal plastic
core member sandwiched therebetween. The skins are bonded to the
core member by a known flexible adhesive layer. The foamed thermal
plastic core member is resilient and may be made from foamed high
density thermal plastic, such as polyethylene or polypropylene, or
foamed low density thermal plastic, such as polyethylene or
polypropylene, or other foamed thermal plastic.
[0011] To make the foamed core member used in the present
invention, foaming beads or pellets are first mixed with thermal
plastic resin beads or pellets by means of an auger in a mixing
chamber. The foaming pellets have a gas therein. The mixed pellets
are subjected to heat in a hot die chamber and the foaming pellets
burst and produce carbon dioxide or nitrogen to foam the mixture.
The mixture is extruded into a layer by an extruder to form the
foamed core member. Thereafter, a layer of flexible adhesive is
preferably applied to the inner surface of the skins by suitable
means, the layer of flexible adhesive can be applied to the
opposite sides of the foamed thermal plastic core member by like
suitable means, an adhesive film can be co-extruded on both sides
of the core member and laminated to the core member immediately, or
the surfaces of the core member can be treated to become the
adhesive bonding layer such that the skins can be directly bonded
thereto. Thereafter, the metal skins are adhered to the core member
by means of the flexible adhesive layer under pressure. This
process may be continuous. It is envisioned that other means of
foaming the core member may be provided such as by injecting
nitrogen into a heating chamber in which the thermal plastic resin
pellets are being heated and are in a molten state and thereafter
extruding the foamed core material into a core member, or by using
both the nitrogen producing beads or pellets and the direct
injection of nitrogen gas into a heating chamber in which the
thermal plastic resin pellets and the nitrogen producing pellets
are being heated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The organization and manner of the structure and operation
of the invention, together with further objects and advantages
thereof, may best be understood by reference to the following
description, taken in connection with the accompanying drawings,
wherein like reference numerals identify like elements in
which:
[0013] FIG. 1 is a perspective view of a trailer having a plurality
of composite plates which incorporate the features of the invention
and which form the walls and the rear doors thereof;
[0014] FIG. 2 is a cross-sectional view of one of the plates of
FIG. 1; and
[0015] FIG. 3 is a schematic view of an apparatus for forming one
of the plates of FIGS. 1 and 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] While the invention may be susceptible to embodiment in
different forms, there is shown in the drawings, and herein will be
described in detail, a specific embodiment with the understanding
that the present disclosure is to be considered an exemplification
of the principles of the invention, and is not intended to limit
the invention to that as illustrated and described herein.
[0017] The present invention discloses a novel composite plate 20
for use in a wall or door construction of a vehicle, such as a
trailer 22, as shown in FIG. 1, van or the like. The trailer 22 is
generally comprised of a floor 24, a roof 26, a front wall 28, a
pair of opposite side walls 30 (only one of which is shown), rear
cargo doors 32, a landing gear 34, and an undercarriage assembly
36. As shown in FIG. 1, the trailer 22 is connected to a tractor 38
by conventional means, such as a fifth wheel.
[0018] Each side wall 30 and the front wall 28 of the trailer 22 is
formed from a plurality of the novel composite plates 20 of the
present invention which are fastened together by suitable means
such as by riveting. Preferably, each composite plate 20 is
rectangular having a height greater than its width. The composite
plates 20 can be relatively equal in size or the width and
thickness of each plate 20 may vary. When composite plates 20 are
used in the construction of the side walls 30 and the front wall
28, each composite plate 20 is connected to the floor 24 and
extends upwardly therefrom and is attached to upper and lower rails
of the trailer 20 by suitable joining members, such as bolts or
rivets. When composite plates 20 are used in the construction of
the rear doors 32, outer composite plates 20 are connected to the
respective side walls 30 of the trailer 22 by hinges. When closed
the doors 32 extend upwardly from the floor 24. Alternatively, each
side wall 30 and the front wall 28 of the trailer 22 may be formed
from one such continuous plate 20.
[0019] Attention is directed to FIG. 2 which shows a cross-section
of one of the novel composite plates 20 used in the construction of
the trailer walls 28, 30 and/or doors 32. The composite plate 20
includes a pair of metal sheets or skins 40, 42 which are bonded to
a foamed thermal plastic core member 44, described more fully
herein, which is sandwiched therebetween by a thin adhesive layer
46 (such thickness of the adhesive layer has been exaggerated in
the drawings for clarity in understanding the invention). The skins
40, 42 are bonded to the foamed thermal plastic core member 44 by
means of a known flexible adhesive bonding film 46. Skin 40 forms
an inner surface of the trailer 22 and skin 42 forms an outer
surface of the trailer 22.
[0020] The metal skins 40, 42 used in the composite plate 20 of the
present invention are preferably formed of aluminum or full hard,
high strength, high tension, galvanized steel. Preferably, the each
of the skins 40, 42 are formed from galvanized steel and
preferably, the inner skin 40 is over nineteen thousandths of an
inch in thickness and the outer skin 42 is over nineteen
thousandths of an inch in thickness.
[0021] The core member 44 is formed from a foamed thermal plastic,
preferably foamed high density polyethylene (HDPE) or high density
polypropylene, which makes the core member 44 resilient. That is,
the core member 44 can flex without breaking. As shown in FIG. 2,
the core member 44 includes a plurality of air bubbles 48
interspersed with the thermal plastic material 50. It has been
found that molecular integrity of the core member 44 is not lost by
the foaming of the core member 44 and peel strength is increased
versus prior art composite plates which use a solid core member.
That is, it takes a greater force to peel the metal skins 40, 42
from the foamed thermal plastic core member 44 than in prior art
solid core composite plates. This is described more fully herein.
The foaming of the core member 44 lowers the density of the thermal
plastic and improves the strength to weight ratio thereof.
Alternatively, the core member 44 may be made from foamed low
density thermal plastic, such as foamed low density polyethylene or
low density polypropylene. Low density thermal plastic will foam
and produce a resilient core member, however, the resulting
composite plate is not as stiff as when foamed high density thermal
plastic is used in the composite plate. When foamed high density
thermal plastic is used as the core member in the composite plate,
the composite plate is approximately twice as stiff as when a
foamed low density thermal plastic is used as the core member in
the composite plate.
[0022] The core member 44 preferably has a thickness of one half of
an inch or less. The core member 44 used in the present invention
is thinner than prior art solid cores which are mush thicker,
typically three quarters of an inch to four inches.
[0023] The foaming of the core member 44 reduces the weight of the
composite plate 22 versus prior art solid core composite plates.
Because the core member 44 is foamed in the present invention and
is not solid as in prior art composite plates, the amount of
plastic resin used in formation of the core member 44 is reduced by
up to 50% versus prior art solid core composite plates.
[0024] As mentioned herein, the foaming of the thermal plastic core
member 44 also increases the peel strength of the resulting
composite plate 20. When the composite plate 22 is subjected to
peel forces, that is, the skins 40, 42 are grasped opposite of each
other and the skins 40, 42 are peeled away from the core member 44,
the entire core member 44 flexes because the foamed core material
is resilient and the peel force is along the length of the core
member 44. Because the core member 44 is resilient and flexes, this
allows for more of the core member 44 to be loaded during
application of peel forces. In the prior art, solid core members
are provided in composite plates and therefore, the peel strength
is low; especially compared to the present invention because the
solid core composite plate are not as resilient. When a solid core
member is used in a composite plate as is used in the prior art, to
peel a skin from the core member, peel force only is applied at a
narrow line of the skin to crack the skin away from the solid core
member.
[0025] In the present invention, peel strength was measured by
means of a peel test. The metal skins 40, 42 were grasped opposite
of each other and the force required to peel the skins 40, 42 from
the core member 44 was measured. It was found that an increase in
peel strength is obtained with the resilient foamed core member 44
of the present invention versus a solid core member as used in the
prior art. This means that in the present invention, the skins 40,
42 are less likely to delaminate from the resilient core member 44
upon impact or because of abuse.
[0026] In prior art solid core composite plates, a high shear
stress is obtained between the metal skins and the solid plastic
core member as the composite plate temperature changes. If shear
stress gets too high, then the metal skins can delaminate from the
core member. The plastic core member expands or contracts fastener
than the metal skins, however, the metal skins will restrict this
expansion when they are bonded to the core member, but high shear
stresses result at the adhesive face. In the present invention,
because the core material 44 is foamed, lower shear stresses of the
skin to core bond layer result as temperature is changed because
the foamed core member can be compressed or expanded because of the
cell structure so as to reduce the potential of delamination of the
metal skins 40, 42 from the thermal plastic core member 44. Thus,
the foamed thermal plastic core member 44 will still expand or
contract faster than the metal skins 40, 42, however, the foamed
thermal plastic core member 44 compresses or expands thereby
neutralizing this faster expansion or contraction such that the
foamed thermal plastic core member 44 expands or contracts at
approximately the same rate as the metal skins 40, 42 and lower
shear stresses result at the adhesive face.
[0027] To make the foamed core member 44 used in the present
invention, as shown in FIG. 3, foaming beads or pellets 52 are
first mixed with thermal plastic resin beads or pellets 54 by means
of an auger 56 in a mixing chamber 58. The foaming pellets 52 have
a gas therein. The mixed pellets 54, 56 are subjected to heat in a
hot die chamber 60 and the foaming pellets 56 burst and produce
carbon dioxide or nitrogen to foam the mixture. The mixture is
extruded into a layer by an extruder 62 to form the foamed core
member 44. Thereafter, a layer of flexible adhesive 46 is
preferably applied to the inner surface of the skins 40, 42 by
suitable means 64, as shown, the layer of flexible adhesive 46 can
be applied to the opposite sides of the foamed thermal plastic core
member 44 by like suitable means, an adhesive layer of film 46 can
be co-extruded on both sides of the core member 44 and laminated to
the core member 44 immediately, or the outer surfaces of the core
member 44 can be treated to become the adhesive bonding layer 46
such that the skins 40, 42 can be directly bonded thereto.
Thereafter, the metal skins 40, 42 are adhered to the core member
44 by means of the flexible adhesive layer 46 under pressure. It is
to be noted that the more gas that is used during the heating step,
the more reduction in core material is ultimately achieved. This
process may be continuous.
[0028] It is envisioned that other means of foaming the core member
44 may be provided such as by injecting nitrogen into a heating
chamber in which the thermal plastic resin pellets 54 are being
heated and are in a molten state (without the foaming pellets 52
being mixed therewith) and thereafter extruding the foamed core
material into a core member 44, or by using both the foaming
pellets 52 and the direct injection of nitrogen gas into a heating
chamber (shown via conduit 61 shown in phantom lines in FIG. 3) in
which both the thermal plastic resin pellets 54 and the foaming
pellets 52 are being heated.
[0029] While a preferred embodiment of the present invention is
shown and described, it is envisioned that those skilled in the art
may devise various modifications of the present invention without
departing from the spirit and scope of the appended claims.
* * * * *