U.S. patent number 3,580,190 [Application Number 05/001,269] was granted by the patent office on 1971-05-25 for pallet construction.
This patent grant is currently assigned to Monsanto Company. Invention is credited to Timothy J. Fowler.
United States Patent |
3,580,190 |
Fowler |
May 25, 1971 |
PALLET CONSTRUCTION
Abstract
A substantially rectangular pallet which can be raised and
transported by forklift truck arms inserted through any one of the
four side edges thereof and which can span across its narrow width.
The pallet has a top deck, a bottom deck, and a structural network
mediate therebetween which all coact together. The structural
network has longitudinally extending and transversely extending
stringer members interconnecting with one another. The pallet
construction is well suited for formation from two, or three
preformed pieces of plastic material and is especially adapted for
use by the food industry in shipping and warehousing
foodstuffs.
Inventors: |
Fowler; Timothy J. (St. Louis,
MO) |
Assignee: |
Monsanto Company (St. Louis,
MO)
|
Family
ID: |
21695191 |
Appl.
No.: |
05/001,269 |
Filed: |
January 7, 1970 |
Current U.S.
Class: |
108/57.25;
108/901 |
Current CPC
Class: |
B65D
19/0012 (20130101); B65D 2519/00343 (20130101); B65D
2519/00562 (20130101); B65D 2519/00373 (20130101); Y10S
108/901 (20130101); B65D 2519/00318 (20130101); B65D
2519/00034 (20130101); B65D 2519/00557 (20130101); B65D
2519/00288 (20130101); B65D 2519/00104 (20130101); B65D
2519/00069 (20130101) |
Current International
Class: |
B65D
19/00 (20060101); B65d 019/18 () |
Field of
Search: |
;108/51--58
;248/119 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gay; Bobby R.
Assistant Examiner: Finch; Glenn C.
Claims
What I claim is:
1. A substantially rectangular pallet construction comprising, in
combination,
A. a top deck,
B. a bottom deck, and
C. a structural network interposed between, and interconnecting,
said top and said bottom deck,
D. said structural network comprising a first set of at least four
elongated, orthotropic beamlike members, and a second set of at
least four elongated orthotropic beamlike members,
E. said first set being normally positioned with respect to said
second set, and interconnected therewith, whereby upper edge
regions and portions of lower edge regions of first set members and
second set members define respective upper and lower faces of said
structural network, and which faces are generally parallel to one
another,
F. said first set members
1. being in generally parallel, spaced relationship to one
another,
2. being symmetrically disposed with respect to a first
hypothetical centerline,
3. having at least two members thereof disposed centrally, and
4. having such centrally disposed members cooperating with the
remainder thereof to define a first pair of zones, one each between
a different pair of such first set members, each such first zone
being adapted to accommodate therewithin a forklift arm,
G. said second set members
1. being in generally parallel, spaced relationship to one another
and not greater in length than said first set,
2. being symmetrically disposed with respect to a second
hypothetical centerline,
3. having at least two members thereof disposed centrally,
4. having such centrally disposed members cooperating with the
remainder thereof to define a second pair of zones, one each
between a different pair of such second set members, each such
second zone being adapted to accommodate therewithin a forklift
arm, and
5. each comprising three platelike portions and two riblike
portions, each such platelike portion extending vertically the full
height of said first set members, one such platelike portion
comprising the central portion of each respective member, the
remaining two such platelike portions each comprising terminal end
segments of each respective such member, each such riblike portion
extending not more than about two-thirds the height of said first
set members and comprising a different interconnecting segment
between two adjacent such platelike portions with upper edge
regions thereof being generally coextensive with those of such
platelike portions, all such platelike portions and all such
riblike portions in each respective such member being symmetrically
disposed with respect to said first hypothetical centerline,
and
H. said first set members having defined therein generally aligned
apertures in said second pair of zones, and said second set members
having defined therein generally aligned apertures in said first
pair of zones whereby such forklift arms can pass into said
structural network through any one of the four side edges
thereof.
2. A pallet construction of claim 1 wherein each of said first set
members comprises three platelike portions and two riblike
portions, each such platelike portion extending vertically the full
height of said first set members, one such platelike portion
comprising the central portion of each respective member, the
remaining two such platelike portions each comprising terminal end
segments of each respective such member, each such riblike portion
extending not more than about two-thirds the height of said first
set members and comprising a different interconnecting segment
between two adjacent such platelike portions with upper edge
regions thereof being generally coextensive with those of such
platelike portions, all such platelike portions and all such
riblike portions in each respective such member being symmetrically
disposed with respect to said first hypothetical centerline.
3. A pallet construction of claim 1 having flexural members
symmetrically positioned in said structural network over said first
pair of zones between said centrally disposed members and the
remainder thereof.
4. A pallet construction of claim 1 composed of a thermoplastic
material having a flexural modulus of at least about 200,000
p.s.i.
5. A pallet construction of claim 1 composed of a thermoplastic
material having a flexural strength of at least about 4,000
p.s.i.
6. A pallet construction of claim 1 having at least a partially
formed third deck positioned in said structural network and
extending generally parallel to said top deck.
7. A pallet construction of claim 1 wherein said bottom deck has
apertures formed therein which are adopted to receive therethrough
the ground-engaging members functionally associated with a pair of
forklift arms in a low lift truck.
8. The pallet construction of claim 1 which is comprised of a
polyolefin polymer.
9. The pallet construction of claim 1 which is comprised of a
polyvinyl aromatic polymer.
10. The pallet construction of claim 1 which is composed of a
fiberglass reinforced thermoplastic polymer.
Description
BACKGROUND
Various specialized pallet constructions have been evolved over the
years by different industries. One type of pallet construction is
extensively used in the food industry for shipping and warehousing
of various types of foodstuffs. This pallet construction has
standardized measurements (usually set at about 48 inches .times.40
inches .times.6 inches), is conveniently formed primarily of wood,
is adapted to be picked up from any side and to be moved by a pair
of standardized forklift arms, and has a substantially flat,
continuous upper surface on its top deck, and also on the lower
surface of its boom deck (except that, in the latter deck, there
may be four apertures through which the four wheels of a
conventional type so-called "low-lift" truck's forklift arms may
extend and ground engage from respective axle positions interior of
the pallet during loaded pallet lifting and transport
operations).
In addition, type of pallet construction is relatively light in
weight (conventionally usually under about 80 pounds). In addition,
it must conventionally meet various load criteria such as: (a)
support with little edge or central sag, a heavy (about 4,000
pounds or more) load on its top deck while being supported by a
pair of standardized forklift arms inserted through any side edge
thereof; (b) support without collapse, and with conventional safety
factors, a heavy (2,500 pounds or more) load on its top deck
without more than a 1/2inch sag while spanning across its shorter
width (e.g. 40 inches) between transversely extending supports
positioned along and under the longer lengthwise (e.g 48 inches)
opposed side edge portions thereof; (c) support, with bottom deck a
substantially complete ground engaging position, without buckling
or experiencing permanent change, a heavy (about 12,000 pounds or
more) load; (d) be stacked in stable tiers up to and including five
pallets high, each pallet bearing a load (2,500 pounds or more)
with a flat upper surface, upper pallets each resting on the upper
surface of the load on the pallet below; and (e) survive a full
corner drop, with only localized corner failure at impact point,
when dropped against flat concrete surface from a height of about 6
feet and an inclination of about 45.degree. with the pallet
unloaded.
For some time, however, users and producers of pallets have desired
to make an improved pallet construction of this type which would
not only be adapted to have the above-indicated standardized
dimensions and load criteria, but which would also have certain
preferred further advantages, such as resistance to contamination
by dirt and microbiological organisms, steam cleanability, and,
hopefully, lighter weight. Although plastic and metal materials
which have strength characteristics suitable for use in an
all-metal, all-plastic or combined metal and plastic construction,
can be selected, not a single pallet construction composed of these
materials, singly or in combination, is known to me which has all
of the above-indicated combination of dimensional and load
criteria.
I have now invented a new and very useful pallet construction which
can, if desired, be formed of plastic (preferred) or metal, or some
convenient combination of the two, and which is readily
fabricatable if desired so as to possess all of the above-indicated
combination of dimensional and load criteria. In addition, by mere
selection of appropriate starting materials, my construction may be
made resistant to dirt and microbial contamination, may be made
steam cleanable, and may be made lighter in weight than
conventional wooden pallets of this type.
SUMMARY OF THE INVENTION
The present invention is directed to an improved substantially
rectangular pallet of the type adapted not only to be raised and
moved by means of a pair of spaced, parallel, generally coplanar
(standardized and conventional) forklift arms inserted in the
pallet interior through any one of the four side thereof, but also
to span when in a loaded condition across its narrow width. The
pallet construction between an interconnected coacting top and
bottom decks. The structural network incorporates both a first set
of at least four elongated, orthotropic beamlike members, and a
second set of at least four elongated, orthotropic beamlike
members. The first set members are normally positioned with respect
to the second set members and are interconnected therewith at
places of contact or crossover. The upper edge regions and portions
of the lower edge regions of first set members and of second set
members define respective upper and lower faces of said structural
network. These faces are generally parallel to one another.
The first set members are in generally parallel, spaced
relationship to one another, and in addition are symmetrically
disposed with respect to a first hypothetical centerline. At least
two members thereof are disposed centrally, and these centrally
disposed members cooperate with the remainder thereof to define a
first pair of zones, one each between a different pair of such
first set members. Each such first zone is adapted to accommodate
therewithin a forklift arm.
The second set members are likewise in generally parallel, spaced
relationship to one another, but are not greater in length than
said first set members. Similarly, they are symmetrically disposed
with respect to a second hypothetical centerline, and at least two
members thereof are disposed centrally.
These centrally disposed members also cooperate with the remainder
thereof to define a second pair of zones, one each between a
different pair of such second set members. Each such second zone is
adapted to accommodate therewithin a forklift arm.
Each member of the second set comprises three platelike portions
and two riblike portions. Each such platelike portion extends
vertically the full height of the first set members, with one such
platelike portion comprising the central portion of each respective
member, and the remaining two such platelike portions each
comprising opposed terminal end segments of each respective such
member. Each such riblike portion extends not more than about
two-thirds the height of said first set members, and comprises a
different interconnecting segment between two adjacent such
platelike portions, with upper edge regions thereof being generally
coextensive with those of such platelike portions. All such
platelike portions and all such riblike portions in each respective
such member are symmetrically disposed with respect to said first
hypothetical centerline.
The first set members have defined therein generally aligned
apertures in the second pair of zones, and the second set members
have defined therein generally aligned apertures in the first pair
of zones, so that forklift arms can pass into the structural
network through any one of the four side edges thereof.
DESCRIPTION OF THE DRAWINGS
The invention is better understood by reference to the attached
drawings wherein:
FIG. 1 is an exploded isometric view of one embodiment of a
three-part pallet construction of this invention, having a top
deck, a bottom deck, and a structural network mediate
therebetween;
FIG. 2 is a top plan view of the structural network of the
embodiment shown in FIG. 1;
FIG. 3 is a longitudinal side elevational view of the embodiment
shown in FIG. 1 with top deck, bottom deck and rib network in an
assembled configuration;
FIG. 4 is a vertical sectional view transversely taken along the
line 4-4 of FIG. 2;
FIG. 5 is a vertical sectional view transversely taken along the
lines 5-5 of FIG. 2 showing, in dotted line configuration, the
position of a forklift inserted transversely to said
embodiment;
FIG. 6 is a vertical sectional view longitudinally taken along the
line 6-6 of FIG. 2, showing, in dotted line configuration, the
position of a pair of forklifts inserted transversely into said
embodiment;
FIG. 7 is a vertical sectional view longitudinally taken along the
line 7-7 of FIG. 2, showing, in dotted line configuration, the
position of a forklift of the so-called low-lift type inserted
longitudinally into said embodiment;
FIG. 8 is a view similar to FIG. 1 but showing a second embodiment
of a three-part pallet construction of this invention having a top
deck, a bottom deck, and a structural network mediate
therebetween;
FIG. 9 is a vertical sectional view transversely taken along the
lines 9-9 of FIG. 8;
FIG. 10 is a vertical sectional view transversely taken along the
line 10-10 of FIG. 8 showing, in dotted line configuration, the
position of a forklift inserted transversely into said
embodiment;
FIG. 11 is a vertical sectional view longitudinally taken along the
line 11-11 of FIG. 8 showing, in dotted line configuration, the
position of a pair of forklifts inserted transversely into said
embodiment;
FIG. 12 is a vertical sectional view longitudinally taken along the
line 12-12 of FIG. 8 showing, in dotted line configuration, the
position of a fork lift of the low-lift type inserted
longitudinally into said embodiment;
FIG. 13 is a vertical sectional view longitudinally taken along the
line 13-13 of FIG. 8 showing, in dotted line configuration,
position of a pair of forklifts inserted transversely into said
embodiment;
FIG. 14 is a vertical sectional view longitudinally taken similar
to FIG. 7 but showing yet another embodiment of a three-part pallet
construction of this invention, having a top deck, a bottom deck,
and a structural network mediate therebetween;
FIG. 15 is a longitudinal side elevational view showing one
additional embodiment of a three-part pallet construction of this
invention, having a top deck, a bottom deck, and a structural
network mediate therebetween;
FIG. 16 is a horizontal sectional view taken along the line 16-16
of FIG. 15; and
FIG. 17 is a transverse side elevational view of the embodiment
shown in FIG. 15.
DETAILED DESCRIPTION
Turning to the drawings, there is seen in FIGS. 1--7 an exploded
view of one preferred embodiment of a pallet construction of this
invention herein designated in its entirety by the numeral 21.
Pallet 21 is seen to comprise three components, a top deck 22, a
structural network 23 and a bottom deck 24. Top deck 22 and bottom
deck 24 are each conveniently formed of a thermoplastic polymeric
material by extrusion, or similar molding technique, conventionally
known to the plastics industry. Structural network 3 is
conveniently formed as a single piece in a conventional molding
operation using a thermoplastic polymeric material. Other materials
of construction such as metal or wood can be used to fabricate in
whole or in part the present invention as those skilled in the art
will readily appreciate.
Although the top deck 22 is continuous and unperforated, the bottom
deck 24 has formed therein four apertures 26 which are positioned
so as to permit the wheels or rollers on a conventional fork lift
assembly of the low-lift type to ground engage when such a forklift
is operatively engaged with an assembled pallet 21 after insertion
through a transverse side edge thereof. The dotted line
configuration of such a forklift assembly 27 is an assembled pallet
21 is shown in FIG. 7. Such a low-lift assembly as such forms no
part of this invention. In general, a deck may be regarded as a
flat, sheetlike member adapted to provide either an upper surface
or top deck, or a lower surface or bottom deck of a pallet
construction. The top deck is preferably continuous; the bottom
deck is preferably apertured as just indicated.
The structural network 23 incorporates a series of six beams or
beamlike members 28, 29, 30, 31, 32, and 33. As shown, these beams
28 through 33 are each flattened, elongated, straight members which
are generally vertically positioned and which extend between top
deck 22 and bottom deck 24, and which extend from one transverse
side edge region to the opposed side edge region, of pallet 21. In
general, in a pallet, a beam or beamlike members may be regarded
for present purposes as a flattened, elongated, straight
configuration which is generally vertically positioned; extends
between, and joins, top and bottom deck at positions of contact
therebetween; extends from one side edge region to the opposed side
edge region; and is apertured appropriately for the passage of
forklifts therethrough. When beams interconnect or intersect, they
join.
Taken together as a set, beams 28 through 33 determine, in effect,
the perimeter of the pallet 21, with beams 28 and 33 defining the
longitudinal side edges of pallet 21, and opposed end portions of
respective beams 28 through 33 indicating the region of transverse
first side edges. All the beams 28 through 33 are symmetrically
positioned with respect to a first (hypothetical) center line 36.
Beams 30 and 31 can be considered to be disposed centrally, while
beams 28 and 29 can be considered to be disposed adjacent one
longitudinally extending side edge portion of pallet 21 while beams
32 and 33 are disposed adjacent the other such side edge portion
thereof. The beams 28 through 33 are arranged so as to define
between, respectively, beams 29 and 30, and beams 31 and 32, a pair
of longitudinally extending (with respect to pallet 21) zones 37
and 38. Each zone 37 and 38 is each adapted to receive as suggested
above, one of a pair of forklift arms (not shown in FIG. 1 but
shown in dotted line configuration of FIG. 7).
The structural network 23 also incorporates a second series of
seven beams 41 through 47. As indicated, these beams 41 through 47
are each flattened, elongated, straight members which are generally
vertically positioned and which have portions that extend between
top deck 22 and bottom deck 24. Such members 41 through 47 extend
from one longitudinal side edge region to the opposed side edge
portion of pallet 21. Taken together as a set, beams 41 through 47
cooperate with beams 28 through 33 to define the perimeter of the
pallet 21. Beams 41 and 47 operate to define the transverse side
edges of pallet 21. All the beams 41 through 47 are symmetrically
positioned with respect to a second (hypothetical) center line 48.
Beams 43, 44 and 45 may be considered to be disposed adjacent one
transversely extending side edge portion of pallet 21 while beams
46 and 47 are disposed adjacent the other transverse side edge
position thereof. The beams 41 through 47 are arranged so as to
define between, respectively, beams 42 and 43 and beams 45 and 46,
a pair of transversely extending (with respect to pallet 21) zones
49 and 50. These zones 49 and 50 are each adapted to receive
therein one of a pair of forklift arms (not shown in FIG. 1, but
see FIGS. 5 and 6) which pair of forklift arms may be inserted
through either opposed longitudinally extending side edge position
of pallet 21.
The first set of beams 28 through 33 is normally positioned with
respect to the second set of beams 41 through 47 and is
interconnected therewith at points of intersection. Thus, taken
together, all the beams cooperate to comprise the structural
network 23. The opposed faces of the structural network are formed
by the respective beam edges. These faces are generally parallel
and opposed to one another.
Each of beams 28 through 33 can be considered to have defined
therein a pair of aperture Thus, beam 28 has apertures 55 and 56,
beam 29 and apertures 57 and 58, beam 30, apertures 59 and 60, beam
31, apertures 61 and 62, beam 32, apertures 63, and 64, and beam
33, apertures 65 and 66. Apertures 55, 57, 59, 61, 63, and 65 are
generally aligned with one another and are generally positioned
between beams 42 and 43, and apertures 56, 58, 60, 62, 64, and 66
are generally aligned with one another and are generally positioned
between beams 45 and 46. Thus, a pair of forklift arms can be
inserted through either beam 28 or through beam 33 so as to enable
the pallet 21 to be picked up and supported by means of forklifts
inserted transversely into the pallet 21.
The construction of beams 41 through 47 differs from the
construction of beams 28 through 33 in pallet 21. Each of beams 41
through 47 can be considered to be composed of two riblike members
and three platelike members. Thus, beam 41 employs plates 67, 68,
and 69, and ribs 70 and 71; beam 42 employs plates 72, 73, and 74,
and ribs 75 and 76; beam 43 employs plates 77, 78 and 79, and ribs
80 and 81; beam 44 employs plates 82, 83, and 84, and ribs 85 and
86; beam 45 employs plates 87, 88, 89, and ribs 90 and 91; beam 46
employs plates 92, 93, and 94, and ribs 95 and 96; beam 47 employs
plates 97, 98, and 99, and ribs 100, and 101. 72, 77, 82, 87, 92,
and 97, extend between and joins top deck 22 and bottom deck 24;
each of the plates 68, 73, 78, 83, 88, 93, and 98 extends between
and joins top deck 22 and bottom deck 24, and extends between and
joins stringers 30 and 31; and each of the plates 69, 74, 79, 84,
89, 94 and 99 extends between and joins top deck 22 and bottom deck
24, and extends between and joins strings 32 and 33. Each of the
ribs 70, 75, 80, 85, 90, 95, and 100 extends between and joins
beams 29 and 30 and the upper edge of each such rib joins top deck
22; and each of ribs 71, 76, 81, 86, 91, 96 and 101 extends between
and joins beams 31 and 32 and the upper edge of each such rib joins
top deck 22. The space under each such tie and bottom deck 24
provides an aperture through which a pair of forklifts can be
inserted for raising and transporting of a pallet 21. A "plate"
generally is a nonapertured portion of a beam which extends between
and joins top and bottom decks, preferably, it extends between and
joins only one pair of adjacent beams in an assembled pallet. A
"rib" generally is a barlike, elongated, flattened, straight member
which extends between and joins only one pair of adjacent plates;
preferably it extends between and joins only one pair of adjacent
beams; The upper edge portion of a rib join the top deck. Such an
end-aligned sequence of ribs plus plates can be considered to be a
beam. In the embodiment shown, the ribs are shown thicker than the
plates for reasons of added strength and load-bearing capacity.
In pallet 21, midway between ribs 75 and 80, and midway between
ribs 90 and 95, extending between beams 29 and 30, are flexural
members 104 and 105 which have their respective upper edges joining
top deck 22. Similarly, midway between ribs 76 and 81 and midway
between ribs 91 and 96, extending between stringers 31 and 32, are
flexural members 106 and 107 which have their respective upper
edges joining top deck 22. Each such flexural member can be
considered to be barlike, elongated, flattened and straight. Such
flexural members are optional in a pallet construction of this
invention, though are preferred in pallet 21. A flexural member
generally is like a rib except that it characteristically extends
between and joins one pair of adjacent beams at positions where
there are no corresponding plates, usually normally.
As indicated, in pallet 21, top deck 22 and bottom deck 24 are each
joined to the edge surfaces of the indicated portions of structural
network 23. The actual joining, since pallet 21 is formed in three
parts, can be achieved by any means known to the art such as
adhesives, sonic welding (preferred), dielectric fusion, mechanical
fastening means, some combination thereof, or the like. Since the
top deck, the bottom deck, and the structural network coact, it is
preferred that these members interconnect with one another at all
places of contact and joining.
Observe that while the flexural members 104 and 105, and 106 and
107 are shorter in depth than ribs 90, 91, 95, and 96 and 75, 76,
80 and 81 in the pallet 21, the flexural members may have and,
preferably, do have a depth equal to the ribs. In general, the
depth of the flexural members are equal to or shorter than the
depth of the ribs. The ribs extend not more than about two-thirds
the height of the first set members.
Observe that the beams 28 through 33 may be structured like the
beams 41 through 47, if desired. The pallet 21 is adapted to span
across its width and may, if desired, also span across its length
if one thickness or strengthens the various beams in the first set
and the second set, especially in the first set.
If desired, the top deck and the bottom deck may be perforated by
small holes, preferably not larger than the width of a beam, so as
to reduce the weight of pallet 21.
In FIGS. 8 through 13 is shown an exploded view of another
embodiment of a pallet construction of this invention herein
designated in its entirety by the numeral 110. Pallet 110 is seen
to comprise like pallet 21 three components, a top deck 111, a
structural network 112, and a bottom deck 113. Pallet 110 may be
fabricated similarly to the manner in which pallet 21 is fabricated
and is similar in appearance and structure except that a third
incomplete deck 114 is positioned in the structural network 112 in
a horizontally extending configuration in the mid region between
upper and lower faces of the structural network 112. This
incomplete third deck 114 of pallet 110 is discontinuous in various
regions, such as those where transversely inserted forklifts are
extended through longitudinal side edges of pallet 110 and in
regions between edge pairs of longitudinally extending beams. Third
deck 114 adds strength and structural rigidity to pallet 110.
Observe that the longitudinally extending beams analogous to the
first set beams of pallet 21 are apertured so that these beams are
continuous in regions below the aperture instead of being open down
to the bottom deck 113 as was the case in pallet 21. Since the
pallet structure of FIGS. 8 through 13 is otherwise similar to that
of the pallet structure of FIGS. 1 through 7, no detailed
description thereof is given herein except that like parts in the
structure of FIGS. 8 through 13 are similarily numbered to the
parts of FIGS. 1 through 7 but with the addition of prime marks
thereto for reference purposes.
In FIG. 14 wherein a third embodiment of a pallet constructure 125
of the present invention is depicted, there is seen a three-part
pallet structure similar to that of pallet 21. In this embodiment,
the structural network incorporates a plurality of flexural members
126, 127, 128, 129, 130, 131, 132, and 133. In addition , the ribs
134, 135, 136, 137 and 138 are flanged on their bottom edges, as
shown.
In FIGS. 15 through 17 is seen a fourth embodiment of a pallet
structure of this invention designated in its entirety by the
numeral 150. Pallet 150 incorporates a top deck 151, a bottom deck
152 and a structural network 153.
Structural network 153 incorporates a first set of beams 156, 157,
158, and 159 in parallel spaced relationship to one another which
are symmetrically arranged with respect to a hypothetical center
line 160. Beams 157 and 158 are disposed centrally. Beam 156 is
disposed adjacent one side edge of pallet 150 and beam 159 adjacent
the opposed side edge thereof. A second set of beams 166, 167, 168
and 169 is similarily arranged in parallel spaced relation to one
another and the individual beams are symmetrically arranged with
respect to a second hypothetical center line 170. The beams 167 and
168 are disposed centrally with stringer 166 being adjacent one
transverse side edge of pallet 150 with beam 169 adjacent the
opposed side edge thereof. The first set of stringers 156 through
159 is interconnected with the second set of stringers at
intersection points. Longitudinally extending apertured,
longitudinally extending zones 171 and 172 and transversely
extending zones 173 and 174 provide four-way forklift axis to
pallet 150 in a manner similar to that accomplished with pallet
21.
The pallet of this invention is preferably constructed of materials
whose flexural strength is greater than about 4,000 p.s.i. and
whose flexural modulus (or Young's Modulus) is greater than about
200,000 p.s.i. A preferred class of materials for use in making
pallets of the invention are glass fiber reinforced; another
preferred class are structural foams. A presently most preferred
material of construction is glass fiber filled
styrene/acrylonitrile copolymers which are foamed. When
construction of a foamed material, is preferred that the foam have
a density ranging from about 0.3 to 0.9 grams per cubic
centimeter.
EXAMPLES
The following Examples are given to illustrate the invention and
not intended to be limitations thereof.
EXAMPLE 1 through 8
Using various thermoplastic materials, a series of pallet
constructions of the type shown in the embodiment of FIGS. 1
through 7 are prepared. The materials of construction, dimensions,
and physical characteristics are as given below in Tables I and II.
##SPC1## ##SPC2##
Pallets of this invention may be constructed of composite
materials; for example, a pallet of this invention can be
constructed of a foamed fiberglass filled styrene/acrylonitrile
material which uses a core of material so foamed with face members
being formed of a substantially nonfoamed material.
Preferably, the bottom deck is champfered at edge regions where the
wheels or skids associated with a low lift truck enter the pallet
interior in lifting and moving operations.
If desired, a pallet construction of this invention can incorporate
metal reinforcement in a thermoplastic material such as rods or
wires of steel or the like.
If desired, the top deck and/or the bottom deck may be corrugated,
especially on the side thereof which faces inwardly toward the
structural network, but the structural network is uniformly bonded
to the so-corrugated member, as described above.
Two classes of thermoplastic polymeric materials suitable for use
in making pallets of this invention are polyolefins (including
polyethylene, polypropylene, and copolymers thereof), and polyvinyl
aromatic polymers (including polymers of styrene, and copolymers
thereof).
A pallet of this invention contains not more than 12 beams in
either the first set or the second set (as these terms are used
herein).
If desired, as those skilled in the art will realize, a pallet of
this invention may incorporate not only transversely extending
flexural members (as this term is used herein), but also
longitudinally extending flexural members, in, for example, the
zones.
* * * * *