U.S. patent number 3,581,681 [Application Number 04/805,739] was granted by the patent office on 1971-06-01 for pallet.
Invention is credited to Irving M. Newton.
United States Patent |
3,581,681 |
Newton |
June 1, 1971 |
PALLET
Abstract
A pallet is constructed of a thin-walled, resinous shell filled
with a foam core bonded to the inside surface of the shell. The
shell includes integral support beams spaced appropriately to
accommodate a forklift for warehousing operations. Materials of
construction are selected to meet strength requirements at minimum
cost.
Inventors: |
Newton; Irving M. (Layton,
UT) |
Family
ID: |
25192383 |
Appl.
No.: |
04/805,739 |
Filed: |
March 10, 1969 |
Current U.S.
Class: |
108/57.28;
108/901 |
Current CPC
Class: |
B65D
19/0018 (20130101); B65D 2519/00338 (20130101); B65D
2519/00288 (20130101); B65D 2519/00268 (20130101); Y10S
108/901 (20130101); B65D 2519/00034 (20130101); B65D
2519/00318 (20130101); B65D 2519/00432 (20130101); B65D
2519/00557 (20130101); B65D 2519/00069 (20130101); B65D
2519/00044 (20130101); B65D 2519/00079 (20130101); B65D
2519/00273 (20130101); B65D 2519/00562 (20130101) |
Current International
Class: |
B65D
19/00 (20060101); B65d 019/18 () |
Field of
Search: |
;108/51--58 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gay; Bobby R.
Assistant Examiner: Finch; Glenn O.
Claims
I claim:
1. A pallet, comprising:
an exterior shell element formed from thin, resinous sheet material
and including:
a body portion having a bottom member and parallel, support beam
members, each of which is formed from approximately parallel,
support beam walls depending from said bottom member and connected
at their distal ends to form a beam base such that the interiors of
said beam members openly communicate with the interior of said body
portion, at two opposite sides and at least one intermediate
location of said bottom member, and
side members extending upward from rigid attachment to the
outermost beam walls at said opposite sides of said bottom member;
and
a core element of rigid resinous foam, conforming in shape and
substantially filling the interior of said shell to form an
approximately flat, upper bearing surface for said pallet, bonded
to the inside surface of said shell.
2. A pallet according to claim 1, wherein the shell element
includes three support beam members depending from opposite sides
and approximately the center, respectively, of the bottom member
and extending the full length of said sides.
3. A pallet according to claim 2 wherein each said support beam
member includes a slot at approximately its center to accommodate
pallet moving means.
4. A pallet according to claim 1, including a platform element of
thin, resinous sheet material mounted atop the approximately flat,
bearing surface of the core element.
5. A pallet according to claim 1, wherein the shell element
includes end-cap members connecting corresponding edges of said
side elements, bottom element, support beam walls, and support beam
bases.
6. A pallet according to claim 5, wherein the shell element is of
unitary construction from resinous sheet material between about one
thirty-second and about one-fourth inch thick.
7. A pallet according to claim 6, wherein the core element is of
rigid foam having a density between about 2 and about 4 pounds per
cubic foot.
8. A pallet according to claim 7, wherein the walls of the shell
element are less than about one-sixteenth of an inch thick.
9. A pallet according to claim 8, including a platform element of
thin resinous sheet material bonded on top of the core element.
Description
BACKGROUND OF THE INVENTION
1. Field
This invention relates to pallets used in warehousing and
transportation for the storage and relocation of goods.
2. State of the Art
A major expense in warehousing and shipping arises from the use of
pallets. Although pallets have traditionally been constructed of
low-cost wood, the initial investment in labor and materials to
construct an adequate supply of pallets for a warehousing operation
is considerable; the procurement expense of pallets is sufficient
that they are customarily reused rather than being discarded. It is
often necessary to ship goods on pallets and then return the empty
pallets to their point of origin. Because wooden pallets are heavy,
their transport, whether loaded or unloaded, adds appreciably to
shipping costs.
Many replacements for conventional wooden pallets have been
suggested, but none of these has gained general commercial
acceptance. Various pallets constructed of resinous materials have
been tried but these generally have one or more disadvantages from
the standpoint of initial investment costs or physical properties.
The plastic or resinous pallet structures of the prior art
generally either lack sufficient strength for large loads or, if
they do possess sufficient strength, are unduly expensive for
general use. Thus, there remains a need for a general purpose, low
cost, lightweight pallet.
SUMMARY OF THE INVENTION
The present invention provides an inexpensive pallet of light
weight but with sufficient strength to support large loads. The
novel pallet structure of this invention makes it possible to form
inexpensive resinous materials by conventional, low-cost,
manufacturing techniques, into pallets of adequate strength at less
cost than typical wooden pallets. Besides conserving on material
and manufacturing costs, the claimed pallet effects a significant
savings on transportation costs compared to presently available
pallets.
In general, the pallet of this invention comprises an exterior
shell element formed from thin, lightweight, resinous sheet
material and a core element of lightweight, rigid, resinous foam,
conforming in shape and substantially filling the interior of the
shell to form an approximately flat, upper bearing surface for the
pallet. The core is bonded by appropriate adhesive or bonding agent
to the inside surface of the shell.
The shell, which constitutes the exterior of the claimed pallet, is
shaped in the general configuration of a conventional pallet,
although conventional wooden pallets often contain structural
reinforcing members which are unnecessary for the pallet of this
invention. Thus, the shell includes an open, or hollow, rectilinear
body portion with depending hollow support beams openly
communicating with the interior of the body of the shell. The body
portion of the shell element may be considered to include a bottom
member which forms the base of the body portion in its normal
position of use. The aforementioned parallel support beam members
are each formed by approximately parallel support beam walls
depending from the bottom member and connected at their distal ends
to form a beam base. The interior of each beam member openly
communicates with the interior of the body portion of the shell.
Support beam members depend from two opposite sides and at least
one intermediate location of the bottom member. According to some
embodiments, the shell is completed by side members extending
upward from rigid attachment to the outermost beam walls at
opposite sides of the bottom member so that the ends of the pallet
normal the beam walls are open. According to other embodiments, end
caps are provided to connect corresponding edges of the body
portion and support beams so that the complete shell is formed as
an enclosure. The core element substantially fills the entire
interior of the shell to provide a bearing surface flush with the
top edges of the side members. If desired, a platform element of
resinous sheet material may be mounted atop the bearing surface of
the core element to provide additional strength and to protect the
core element from abrasion in use. More often, the shell is
open-topped and the pallet load is placed directly on the bearing
surface of the core element.
Shell elements and platform elements for the claimed pallet may be
formed from thin, resinous sheets by conventional vacuum forming,
shell molding, casting, or other techniques. By "thin" is meant of
small dimension relative to the body portion and support beams of
the pallet structure. Thus, a shell element formed from a thin,
resinous sheet will have an interior volume many hundreds of times
greater than the volume of material in the shell. The support
beams, for example, typically have hollow interior volumes to
accommodate a rigid foam core at least about 10 times as thick as
the resinous sheet material defining the beam walls and beam base.
Although it is possible to construct the pallets of this invention
from sheet materials as thick as one-eighth to one-fourth inch or
more, such heavy material is ordinarily not required. The preferred
sheet material for use is the least expensive available which has
sufficient strength and toughness to give satisfactory performance
in use. Thus, contrary to suggestions of the prior art, the
resinous sheet materials most often employed for the production of
pallets according to this invention are less than about
one-sixteenth of an inch thick. Materials as thin as about one
thirty-second of an inch or less are satisfactory for many
applications.
The shell material may be selected from a broad range of resinous
sheet materials. Any resinous organic material susceptible to
conventional forming techniques and which is solid and
noncrystalline at ambient temperatures may be used. The material
selected for use in a particular instance may depend upon the
environment in which the pallet is used. For example, if extreme
climactic or load conditions are to be encountered, a material with
suitable properties to withstand these conditions is preferred over
more susceptible materials, particularly when the pallet is
intended for reuse. By way of example, suitable resinous sheets may
be selected from the condensation polymers, such as the polyesters,
including cellulose esters, polyamides, phenol aldehydes, and urea
and/or melamine formaldehydes; vinyl polymers, such as polyvinyl
acetate, polyvinyl chloride, polyvinylidene chloride, acrylates,
methacrylates, and polystyrenes; polyolefins, notably polyethylene,
polypropylene, or other copolymers of ethylene and/or propylene
with unsaturated esters; cellulose ethers; polyurethanes;
indenecoumarone; and various epoxide-type resins.
The core material should have sufficient rigidity and resistance to
compression to withstand compressive loads. Thus, a rigid foam is
generally preferred. Many suitable rigid foams are known to the
art, and the form employed in the pallet structure of this
invention will generally be selected on the basis of cost and
compatibility with the resinous sheet material selected for the
shell element. Suitable materials may be selected from the various
rigid polyurethane, polycarbonate, and polystyrene foams commonly
used in the construction and appliance industries for noise and
temperature insulation. Foam densities between about 2 and about 4
pounds per cubic foot are preferred, although foams of greater or
less density may be used in particular instances.
The bonding systems known to the art for bonding the selected rigid
foam to the resinous material of the shell may be employed to
effect a high-strength, physical bond between the shell and the
core. It is often possible to cast the core in the shell in the
presence of the bonding agent so that the core solidifies in place,
tightly bonded to the interior surface of the shell.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, which illustrate what is presently regarded as the
best mode for carrying out the invention:
FIG. l is a pictorial view from the top of one form of the
invention;
FIG. 2, a similar view from the bottom; and
FIG. 3, a sectional view taken along the line 3-3 of FIG. 1.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
The pallets illustrated include a shell element 10 comprising a
body portion 11, having a bottom member 12 (FIG. 2); three support
beam members 13-1, 13-2, and 13-3 depending from the bottom member
12, as illustrated; and side members 14-1 and 14-2, extending
upward from attachment to the outside walls 13-1a, and 13-3b,
respectively, of the beams 13-1 and 13-3. Each beam member 13-1,
13-2, and 13-3 is constructed of two beam walls a and b,
respectively, connected at their distal ends by a beam base c. For
example, referring to FIG. 3, support beam 13- 2 is formed by
parallel beam walls 13-2a and 13-2b connected by beam base
13-2c.
In the illustrated instances, the shell element is vacuum formed as
a unitary structure including end cap members 15 so that it forms
an open-topped enclosure with a rectilinear upper perimeter. The
support beams 13 are hollow and openly communicate with the
interior of the body element 11.
In the specific embodiment of FIG. 2, slots 16-1, 16-2, and 16-3
are provided at about the center of the support beam 13-1, 13-2 and
13-3, respectively. Such slots are just sufficiently wide; e.g.,
about 10 inches, to accommodate pallet-moving means so that the
pallet and its load may be withdrawn from a stored location even
when its ends 15 are blocked. The support beams 13, are
sufficiently spaced to accommodate conventional pallet-handling
equipment, such as forklifts.
A core 17 of rigid polyurethane foam is cast in place in the shell
to substantially fill the entire interior thereof and provide a
flat bearing surface flush with the upper edges of the end caps 15
and sidewalls 14. If desired, a load-bearing platform element (not
shown) of resinous sheet material similar to that of the shell
element may be bonded to the top of the core member in the same
fashion that the core element is bonded to the interior surface of
the shell element.
Pallets, such as those illustrated, have been constructed of shells
molded from 1/8-inch ABS-GSE polyethylene plastic sheets filled
with 4 pound polyurethane rigid foam bonded to the shell with
conventional polyester bonding agent. The shell walls of such
pallets are less than one-eighth of an inch thick, yet are capable
of withstanding static loads in excess of 9,600 pounds. They are
nevertheless lighter in weight and cheaper to manufacture than
conventional wooden pallets.
Reference herein to details of the illustrated embodiments is not
intended to limit the scope of the claims which themselves recite
those details regarded as essential to the invention. It is
recognized, for example, that various structural modifications may
be made to the embodiments illustrated to adapt them for specific
uses or to enhance their strength properties. Although the
illustrated beam members are of simple construction and provide
good strength properties, it is recognized that other shapes and
dimensions are possible.
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