U.S. patent application number 11/358866 was filed with the patent office on 2006-11-16 for fire-collaspible cross-beamed pallet.
Invention is credited to Ronald P. Brochu, Roy E. JR. Moore, Daniel J. Swistak.
Application Number | 20060254475 11/358866 |
Document ID | / |
Family ID | 36917115 |
Filed Date | 2006-11-16 |
United States Patent
Application |
20060254475 |
Kind Code |
A1 |
Moore; Roy E. JR. ; et
al. |
November 16, 2006 |
Fire-collaspible cross-beamed pallet
Abstract
A plastic pallet has reinforcing beams which fail during a fire
due to the effects of heat, so the pallet prematurely collapses and
thus the rate of heat evolution is diminished, sufficient to meet
fire standards. In one embodiment metal beams embedded in the
plastic of the pallet have lengths which are shorter than the span
between the rails of a pallet rack. They drop down and cause pallet
collapse, when the surrounding plastic softens or melts. In another
embodiment, the beam is a metal, fiberglass or graphite reinforced
composite thermoplastic, which loses strength when the matrix
softens or otherwise fails. In another embodiment, a metal beam has
two parts which are connected by a thermoplastic fitting which
softens and the fails during a fire.
Inventors: |
Moore; Roy E. JR.;
(Killingworth, CT) ; Brochu; Ronald P.; (Richmond,
KY) ; Swistak; Daniel J.; (Newmarket, NH) |
Correspondence
Address: |
CANTOR COLBURN LLP
55 Griffin Road South
Bloomfield
CT
06002
US
|
Family ID: |
36917115 |
Appl. No.: |
11/358866 |
Filed: |
February 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60654759 |
Feb 18, 2005 |
|
|
|
Current U.S.
Class: |
108/51.11 |
Current CPC
Class: |
B65D 19/38 20130101;
B65D 2519/00562 20130101; B65D 2519/00318 20130101; B65D 2519/00034
20130101; B65D 2519/00129 20130101; B65D 2519/00323 20130101; B65D
2519/00333 20130101; B65D 2519/00268 20130101; B65D 19/0073
20130101; B65D 2519/00343 20130101; B65D 2519/00432 20130101; B65D
2519/00069 20130101; B65D 2519/00407 20130101; B65D 2519/00044
20130101; B65D 2519/00139 20130101; B65D 2519/00288 20130101; B65D
2519/0086 20130101; B65D 2519/00412 20130101; B65D 2519/00557
20130101; B65D 2519/00024 20130101; B65D 2519/00273 20130101 |
Class at
Publication: |
108/051.11 |
International
Class: |
B65D 19/00 20060101
B65D019/00 |
Claims
1. A thermoplastic pallet, useful for transporting goods by means
of forklift devices, the pallet storable in a rack having opposing
side rails, by resting opposing lengthwise edges of the pallet on
the rails, the pallet comprising: a plastic portion configured to
span the distance between the rails of the rack, wherein at least
one cross beam is secured on or within said plastic portion, the
cross beam and plastic portion configured such that said cross beam
and plastic portion will structurally fail upon exposure to heat
from a fire.
2. A thermoplastic pallet in accordance with claim 1, wherein said
at least one cross beam has a length and location within the
pallet, so that one end of the beam is configured such that it is
inward from the lengthwise edge of the pallet and inward from the
vertical extension of the inner edge of the rail of the storage
rack, and wherein, when the plastic portion softens, the end of the
beam will fall downwardly from the rack.
3. A thermoplastic pallet in accordance with claim 1, wherein said
at least one cross beam has a length and location within the
pallet, so that both ends of the beam are configured such that they
inward from the lengthwise edges of the pallet and inward from the
vertical extension of the inner edges of the rail of the storage
rack, and wherein, when the plastic portion softens, an end of the
beam will fall downwardly from the rack.
4. A thermoplastic pallet in accordance with claim 1, wherein said
at least one cross beam includes at least one reinforcing material
engineered to degrade when exposed to heat from a fire, such that
the reinforcing beam will fail upon exposure to heat from a
fire.
5. A thermoplastic pallet in accordance with claim 4, wherein said
cross beam comprises two materials that will not melt or degrade
upon exposure to heat from a fire, coupled with a material that
will melt or degrade upon exposure to heat from a fire, such that
the beam will fail upon exposure to such heat.
6. A thermoplastic pallet in accordance with claim 5, wherein said
cross beam comprises lamellae bound by a thermoplastic or other
heat degradable adhesive, or by an injected encapsulating plastic
layer.
7. A thermoplastic pallet in accordance with claim 1, wherein said
cross beam is at least partially embedded in plastic.
8. A thermoplastic pallet in accordance with claim 1, wherein said
cross beam is a metal material.
9. A thermoplastic pallet in accordance with claim 1, wherein said
cross beam is a composite material.
10. A thermoplastic pallet in accordance with claim 2, wherein said
pallet includes a plurality of cross beams, and wherein at least
two of the beams have ends that overlie different rack rails.
11. A thermoplastic pallet in accordance with claim 1, wherein said
pallet includes at least one beam that is configured to be
generally parallel to a rack rail.
12. A thermoplastic pallet in accordance with claim 1, wherein said
cross beam is a perforated steel box beam.
13. A thermoplastic pallet in accordance with claim 1, wherein
width of the pallet is 48 inches and the length of the cross beam
is no more than 42 inches.
14. A thermoplastic pallet in accordance with claim 1, wherein the
pallet includes a plurality of cross beams, and wherein all cross
beams have the same length.
15. A thermoplastic pallet in accordance with claim 9, wherein the
composite is a fiber selected from the material group consisting of
metal, graphite and glass.
16. A method of reducing the rate of evolution from a thermoplastic
pallet during a fire, wherein the pallet is stored in a rack, the
opposing lengthwise edges of the pallet resting on opposing side
rails of the rack; wherein the pallet has at least one cross beam
provided in the pallet and running at least partially between said
opposing sides to provide strength to the pallet, wherein said at
least one cross beam is configured to fail relative to a remainder
of the pallet upon exposure to heat from a fire.
17. A method in accordance with claim 16, wherein the cross beam
has with a length and location within the pallet, so that an end of
the cross beam lies inwardly from the vertical plane of the
innermost portion of a rail of the rack when the pallet is stored
in a rack, so that when the material of the pallet weakens upon
heating in a fire, the end of the cross beam drops downwardly to
thereby enable the pallet to fall downwardly and reduce the rate of
heat evolution.
18. A method in accordance with claim 16, wherein the cross beam
includes at least one component that is designed to fail upon
exposure to the heat of a fire to thereby enable the pallet to fall
downwardly and reduce the rate of heat evolution.
19. A method in accordance with claim 18, wherein said cross beam
comprises two materials that will not melt or degrade upon exposure
to heat from a fire, coupled with a material that will melt or
degrade upon exposure to heat from a fire, such that the beam will
fail upon exposure to such heat.
20. A method in accordance with claim 19, wherein said cross beam
comprises lamellae bound by a thermoplastic or other heat
degradable adhesive, or by an injected encapsulating plastic layer.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional
Patent Application Ser. No. 60/654,759, filed Feb. 18, 2005, the
entire contents of which are specifically incorporated herein by
reference.
BACKGROUND
[0002] The present disclosure relates to plastic pallets,
particularly those used for transporting miscellaneous industrial
and commercial goods by means of forklift devices and the like,
suitable for use within warehouses.
[0003] Plastic pallets have been in use for a long time, but have
not gained wide acceptance due to the failure to satisfactorily
meet a variety of criteria, including standards of Grocery
Manufacturers of America (GMA). Among the criteria in the standard
are that pallets have fire resistances, sufficient to not exceed
the heat release set by Underwriters Lab Standard 2335 when
intentionally set on fire in a test facility, to simulate a
warehouse fire. The pallet also must not be too heavy, must be
strong enough to carry specified loads, and must be durable in
resisting damage during use, as measured by certain tests and field
use. So far, no pallet has been able to meet all these criteria.
Indeed, the more fire retardant included in the plastics, the more
fragile the plastic. Other problems include include excess weight,
toxicity of the fire retardants, and cost. Thus, other approaches
are sought.
[0004] Pallets are stored with and without goods in warehouses,
typically in metal racks. Usually, when a fire occurs, many pallets
will bum irrespective of the types and distribution of goods stored
on the pallets. Where plastic pallets are utilized, and since such
pallets may have a great deal of exposed plastic surface area, the
heat and rate of combustion of the pallet will be high. A
conflagration can result which overwhelms the sprinkler systems of
the typical warehouse, particularly one which is designed for wood
pallets (which evolve less heat with less rapidity).
[0005] U.S. Pat. No. 6,705,237 "Plastic Pallet Design" of Moore et
al., the entire contents of which are specifically incorporated
herein by reference, discloses a novel thermoplastic pallet
comprising rectangular cross section hollow metal beams. The beams
may form a structural framework within the spaced apart planes of
the bottom and or top parts of the pallet. A pallet using the
invention can meet the above-described load standards. Two beam
arrays may be used, one near the deck when it is plastic and one
near the base. If the deck is strong enough, as may be the case for
some pallets, then the beams may be present only at the base.
[0006] United States Patent Application Publication No. US
2004/0216648 to Apps et al. discloses a thermoplastic pallet having
a continuous metal beam running around the periphery of the pallet
for strength; and, the beam is shaped and centered in the pallet so
that the outer edges are inboard of the rails which support the
pallet on a rack. The construction and performance of the Apps et
al. pallet are different from those of the present pallet, which
has different beam structure.
SUMMARY
[0007] The above described and other disadvantages are overcome or
alleviated by the present thermoplastic pallet having reinforcing
cross beams which preferentially fail. Such pallet may be
constructed such that the beams preferentially fail, so that when
the pallet heats up in a fire, the pallet collapses and the amount
of exposed plastic, and the amount of heat evolution is reduced. In
an exemplary embodiment, the reinforcing beams, for example metal
beams, are embedded in plastic. The beams run parallel to the plane
of a deck of the pallet, and transverse to the length of the pallet
and associated storage rack rails which support the opposing sides
of a stored pallet.
[0008] In one exemplary embodiment, cross beams have lengths which
are shorter than the spacing between the interior edges of the
rails of a pallet rack. In another exemplary embodiment, one end of
a cross beam is above the rail of a rack, while the other end is
not, due to choice of length and side-to-side positioning of the
beam within the pallet. The beams may be uniformly offset to one
side, or they may be staggered in their offsets. Thus, in any
embodiment, when the plastic of the pallet softens during a fire,
one end of a beam will fall from the proximate edge of the rack as
the plastic yields under the load of the beam. When one or more
beams fail, the pallet will collapse, as is desired.
[0009] In another exemplary embodiment, a pallet has a beam with a
composite structure; that is, the beam is reinforced, such as e.g.,
with metal, glass or graphite fiber, within a matrix, such as a
thermoplastic. The plastic matrix is designed to soften during a
fire, so that the reinforcement is no longer held therein and so
that the pallet collapses. In another exemplary embodiment, the
beam comprises fibers of lamellae. In another exemplary embodiment,
the beam comprises thin sheet metal pieces. In another exemplary
embodiment, a cross beam comprises two pieces that are attached to
each other by a thermoplastic connector.
[0010] The foregoing and other objects, features and advantages of
the present pallet will become more apparent from the following
description of exemplary embodiments and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Referring now to the accompanying FIGURES, which are meant
to be exemplary and not limiting:
[0012] FIG. 1 shows a bottom side of an exemplary plastic pallet
having an array of beams which are embedded in the bottom of the
pallet;
[0013] FIG. 2 shows a detail of the top cross section view of an
exemplary pallet corner;
[0014] FIG. 3 is a vertical elevation end view of exemplary pallet
supported in a warehouse rack along its opposing lengthwise
ends;
[0015] FIG. 4 is a front elevation view of an exemplary beam
incorporated in a pallet;
[0016] FIG. 5 is a bottom view of a pallet incorporating a
plurality of exemplary beams;
[0017] FIG. 6 is a bottom view of a pallet incorporating a plurlity
of exemplary beams;
[0018] FIG. 7 is a bottom view of a pallet incorporating a plurlity
of exemplary beams;
[0019] FIG. 8 is a cross sectional view of an exemplary tubular
beam and connector; and
[0020] FIG. 9 is a cross sectional view of an exemplary tubular
beam construction.
DETAILED DESCRIPTION
[0021] The presently disclosed fire collapsible beam pallet
recognizes that when there is a warehouse fire involving molded
plastic pallets which are stacked one above another in a warehouse
rack, the rate of heat output will be mitigated if the surface area
of plastic pallet material which is exposed to flames is reduced.
Thus, as described by exemplary embodiments herein, a pallet
subjected to the heat of a fire desirably fails and falls from the
rack. Such pallet may fall onto an underlying pallet and goods, or
onto the floor. When multiple pallets sandwich together, the
exposed surface area of burnable material will be reduced, and the
access of oxygen bearing atmosphere is inhibited.
[0022] Referring now to FIG. 1, a bottom side of an exemplary
plastic pallet 20 is illustrated, wherein an array of beams is
embedded in the bottom of the pallet. Without being limited, pallet
20 may be constructed in accord with the aforementioned commonly
owned U.S. Pat. No. 6,705,237 to Moore et al., the disclosure of
which is hereby incorporated by reference. The embedded beams are
represented in this and other figures by dashed lines.
[0023] Referring still to FIG. 1, the exemplary beam array
comprises lengthwise beams 24 and cross beams 26. (Length and width
are arbitrary in this disclosure, except that a pallet is
considered to mount in a rack with its length parallel to the rails
30 of the rack.) In one embodiment, the beams are perforated steel
box beams. In another exemplary embodiment, the beams run around
the rectangular periphery of the pallet. In another exemplary
embodiment, the beam ends are close to each other, but the beams
are not structurally attached to each other.
[0024] Referring now to FIG. 2, a detail of the top cross section
view of an exemplary pallet corner is illustrated. The beams cross
in the center of the pallet. The beams may be in the base and top
frame of the pallet and are generally parallel to the plane of the
pallet, that is to the plane of the goods-carrying deck 34 at the
top of the pallet.
[0025] In one exemplary embodiment, the pallet has a metal deck. In
such embodiment, beams are provided in the rails which comprise the
base of the pallet. While the above describes exemplary metal
reinforcing beams, beams made of other materials, for example
composite plastic materials, such as graphite reinforced plastic,
or some strong ceramic, may be used. The beam is, in general terms,
a member, partially or fully surrounded by the thermoplastic of the
pallet (though not necessarily embedded therein), having
substantially different properties, in particular, higher elastic
modulus and tensile strength.
[0026] Referring now to FIG. 3, a vertical elevation end view of
exemplary pallet 20 is illustrated as supported in a warehouse rack
along its opposing lengthwise ends 36. The opposing sides 36 of the
pallet rest on opposing side lips of L-shape cross section rails 30
of an exemplary pallet storage rack. Without being limiting, the
distance between the inner edges of the racks, RL, is typically
about 42 inches, to receive a typical pallet which is 48 inches
wide.
[0027] Referring still to FIG. 3, in another exemplary embodiment,
the cross beams 26 have a length LB which is less than the spacing
RL between the rails, and the beams are centered between the
opposing lengthwise sides 36. Thus, there is a gap G between the
vertical extension of the ends of the beams and the vertical
extension of the inner edges of the lips of the pallet rack. As
used herein, a beam which is shorter than the width between the
rack edges is called a "short beam". Of course, there is some
clearance between the vertical sides of the rails of the rack and
the outside edges of the pallet. Thus, in another exemplary
embodiment, the lengths of beams 26 are sufficiently short to
accommodate the resultant play or possible shifting from side to
side of a pallet mounted in the rack. Thus, in all cases with
regard to this exemplary embodiment, the end of a beam 26 will not
be above the vertical extension of the innermost edge of the rail.
In other exemplary embodiments, e.g., where one end may extend
beyond said vertical extension, and the other does not, the length
and/or position of the beams may chosen accordingly to anticipate
shifting within the rack.
[0028] In accordance with the above exemplary embodiments, in the
event of a fire, the plastic of the pallet softens and loses
strength, and or burns away, and cross beam 26 will no longer be
supported at one or both of its ends. As the plastic softens or
disappears, the one end of the pallet will fall from the rail, and
the pallet will collapse into the space between the rails.
[0029] Referring now to FIG. 6, in another exemplary embodiment, at
least one beam 26A is offset (although all beams may be) from one
lengthwise edge so that one end of the beam is vertically above the
rack rail, but the other end is not. In this exemplary embodiment,
the cross beams may be short beams, or they may have lengths which
are equal or greater than the space between the rail inner
edges.
[0030] As illustrated in FIG. 1, lengthwise beams 24 run generally
parallel to the rails and generally transverse to the cross beams.
Lengthwise beams 24 need not have the features of the cross beams.
Of course, if the pallet is intended also for mounting in racks
which hold the pallet cross-wise, then beams 24 may have the same
features as are described for cross beams 26. In a pallet having
the desired cross beam features described herein, beams 24 may be
displaced inwardly relative to the edges of the rails of the rack,
as for example, shown in FIG. 4 and FIG. 7. Because, in this
exemplary embodiment, the lengthwise beams are not structurally
attached to the cross beams, the engineered pallet works even when
both lengthwise beams lie vertically above the rack rail when the
pallet is stored.
[0031] Referring now to FIGS. 5-7, exemplary beam configurations
are illustrated. FIG. 5 illustrates an exemplary configuration
wherein beams 26 overlie one cross rail 30, but not another.
[0032] FIG. 6 illustrates an exemplary embodiment wherein cross
beams 26 are staggered in their offset. Beams 26A are offset to the
right, and beam 26B is offset to the left. So, in use two of the
beam ends at one side of the pallet have a gap G3 relative to the
rail 30L, while the other beam end has a gap G4 relative to rail
30R.
[0033] FIG. 7 illustrates an exemplary embodiment wherein cross
beams 26 are all offset to one side of the pallet. That is, the
ends are farther from one side than from the other side. Thus, in
use all the beam ends will be farther from the rail 30L than from
rail 30R. Lengthwise beams 24 are also incorporated into the
pallet.
[0034] In the foregoing and following embodiments, at least one
cross beam incorporates the features described. If a pallet has a
beam which fully spans the space between the opposing sides of the
rack, when one or more of the other beams are configured as
described above, in a fire, the pallet can be sufficiently weakened
by the loss of support of the short or offset beams, such that it
will tip around the one or more full length beams.
[0035] Referring now to FIG. 8, another exemplary embodiment,
incorporates a metal cross beam 26D made of two pieces joined by a
press-fit thermoplastic connector 32. In another exemplary
embodiment, the connector is offset from the center of the beam
length, so it is not under a column. In such embodiment, there will
be less mass of plastic to provide thermal inertia and inhibit
heating and softening during a fire. The plastic of the connector
may have the same or different properties, as compared to the
plastic of the pallet. When there is a fire, the plastic of the
connector 32 melts and fails, under the stresses imposed by the
pallet weight and whatever load is on the pallet, and the pallet
collapses. In this embodiment and the following two embodiments,
the lengths of the cross beams may be short or of regular
length.
[0036] As mentioned above, in all cases, the beam need not be a
metal material, but may comprise other materials. In another
exemplary embodiment, a beam is made of composite plastic material,
for instance a strong fiber reinforcement, which beam in
incorporated into a less strong matrix or molding compound. The
matrix is chosen so that it deteriorates when heated, so that the
reinforcing material can no longer serve its purpose and the beam
collapses. For example, the beam may comprise long strand glass
fibers or graphite fibers contained in a thermoplastic matrix which
may or may not be different from the thermoplastic material of the
pallet. The matrix softens and yields when there is a fire. Thus,
the fibers will be no longer firmly gripped, relative to one
another. The beam then loses its structural modulus, its shape, and
its load capacity, and it and the pallet collapse. As an example,
the reinforcement may be glass or graphite or metal fiber and the
matrix may be high density polyethylene HDPE, polypropylene PP,
polysufone PSF, polyethersulfone PES, or analogous material
[0037] In another exemplary embodiment, the beam comprises
lamellae, such as strips of sheet metal or strands of wire. For
example, the cross section of FIG. 9 shows tubular beam 26F,
comprising shaped pieces of light metal angles 34, held together
using a thermoplastic or other heat degradable adhesive, or an
injected encapsulating layer, as suggested by the dashed line 36 in
the Figure. In a fire, the adhesive fails and the beams fails.
While softening is the likely intentional failure mode of the
plastics and matrixes here, other modes of failure due to heating
may ensue.
[0038] In certain exemplary embodiments, the beam is described as
embedded in plastic. It should also be recognized that simply
placing the beam near such plastic may be sufficient, as long as
melting of the plastic causes the beam to fail or displace. For
example, suitable arrangements include placing the beam in a slot,
wherein the beam may be partially exposed. Particularly for those
embodiments which used a composite structure beam, there may be
openings or thinner sections in the plastic around the beam, to
speed localized heating and weakening of the beam during a
fire.
[0039] The principles of the invention may also be applied to other
products where there is a static load or dynamic load on the
product and the structure desirably loses its strength in event of
a fire or other thermal excursion.
[0040] While exemplary embodiments have been shown and described,
various modifications and substitutions may be made thereto without
departing from the spirit and scope of the invention. It is to be
understood that the present invention has been described by way of
illustration and not limitation.
* * * * *