Pallet of unitary construction

There is disclosed a lightweight pallet base of unitary, one piece construction fabricated of a stiff foldable sheet material such as corrugated cardboard. In one aspect the pallet comprises a central platform having foldable corner and side flaps attached to the central platform. The corner flaps and a portion of the side edge flaps adjacent the corners are folded and interlocked to form corner support members. The central portion of the side edge support members are folded to form side edge supports located midway between the corners of the platform. The support members are of one piece construction with the central platform with the pallet being assembled from a die cut blank. Different embodiments of the unitary pallet use the foldable side edge flaps located adjacent the corner flaps in different ways to reinforce the corner support members. In another aspect a load bearing pallet tray is secured to the unitary pallet base which provides a combination having improved beam strength.

FIELD OF THE INVENTION 
The present invention relates to a pallet made of stiff, foldable sheet 
material such as corrugated cardboard. 
BACKGROUND OF THE INVENTION 
The need for lightweight, economical and recyclable pallets is well known. 
Lightweight pallets of corrugated cardboard are known with one type being 
disclosed in U.S. Pat. No. 4,792,325 and another disclosed in U.S. Pat. 
No. 4,867,074. These references disclose corrugated cardboard pallets 
having intersecting stringers and runners forming a platform with the 
stringers and runners separately constructed of multi-layered panels which 
are relatively expensive to produce. United Kingdom Patent No. 955,035 
discloses a pallet having a paperboard load carrying platform and corner 
supports comprising cylindrical cores attached to the platform by strips 
engaging the cores and passing through slots in the corner of the platform 
which are secured to the top surface of the platform. A drawback to this 
type of pallet and other related prior art pallets is that the support 
members separately attached to the central platform are prone to being 
knocked off by e.g. the forks of a fork lift truck or all the weight of 
the pallet bearing down on one of the supports during movement of the 
pallet. Another drawback with pallets formed of different materials is 
that the pallets have to be disassembled and sorted prior to being 
recycled which increases the costs of recycling. 
Accordingly, it would be advantageous to provide a pallet fabricated of a 
light, foldable material having a central load carrying platform and 
support members attached thereto of one piece or unitary construction to 
give an economical, lightweight and readily recyclable pallet. 
SUMMARY OF THE INVENTION 
In one aspect of the invention there is provided a pallet blank fabricated 
of a stiff foldable sheet material. The blank comprises a central platform 
having corner portions and side edges with the central platform having 
first and second opposed surfaces. The blank includes a corner flap 
located at each corner portion of the central platform and at least two 
spaced side flaps attached to each side edge of the central platform. Each 
side flap on each side edge has a first end adjacent a corner flap and a 
second end opposed to the first end. The corner flaps and side flaps are 
of one piece unitary construction with the central platform. Each side 
flap is attached to the central platform side edge along a first fold line 
extending from the first end to a first position spaced from the second 
end of the side flap. Each side flap is detached from the central platform 
along a cut line extending from the first position to said second end, the 
corner flaps and the side flaps being foldable out of plane of the central 
platform. Each corner flap is foldable to overlap itself and securable in 
a position extending out of the plane of the central platform The second 
ends of the side flaps are foldable towards and inwardly of the adjacent 
corner flap and are securable to the central platform. The foldable corner 
flap and the adjacent foldable side flaps form a corner support member 
extending out of the plane from the central platform when the pallet blank 
is assembled into a pallet. 
In another aspect of the invention there is provided a pallet fabricated of 
a stiff foldable sheet material comprising a generally rectangular central 
platform having corner portions and side edges. The central platform has 
opposed first and second surfaces. Included is a corner support member at 
each corner portion of the central platform comprising the assembled 
combination of a corner flap located at each corner portion of the central 
platform and a side flap attached to the side edge of the central platform 
on each side of the corner flap. Each side flap on each side edge has a 
first end located adjacent the corner flap and a second end opposed to the 
first end. The corner flaps and side flaps are of one piece construction 
with the central platform. Each side flap is partially attached to the 
central platform side edge along a fold line extending from the first end 
to a first position spaced from the second end of the side flap. The 
corner flaps and the side flaps are folded in a direction of the plane of 
the central platform. In the assembled combination each corner flap is 
folded to overlap itself and secured in position to extend out of the 
plane of the central platform. The second ends of the side flaps are 
folded towards and inwardly of the adjacent corner flap and are secured to 
the central platform.

DETAILED DESCRIPTION OF THE INVENTION 
In the ensuing description of the structure and operation of the pallet 
embodying the subject invention, reference will be made to the drawings 
wherein like numerals refer to like parts. Referring first to FIG. 1, a 
generally rectangular die cut blank 30 of a first embodiment of a pallet 
base comprises a central support area or platform 32 bounded on each side 
by three spaced, flaps including a central flap 34 and two side flaps 36 
located on either side of flap 34 adjacent the corners of the platform. 
Blank 30 is preferably fabricated of a stiff, foldable sheet material such 
as corrugated cardboard. Corner panels 40 are located at the corners of 
blank 30 between side flaps 36 on adjacent sides of the blank. The solid 
lines in FIG. 1 represent cut lines extending through blank 30 so that 
after being die cut, triangular corner portions 42 are discarded. The 
broken lines in FIG. 1 represent crease or fold lines so that central 
flaps 34 each comprise a central panel 50 attached to platform 32 along a 
fold line 52. Located on each side of central panel 50 is a panel 54 
attached to central panel 50 along a fold line 56 which is collinear with 
a cut line 58 extending to the outer edge of flap 34 thereby separating 
the outermost portions of panels 50 and 54. Panel 50 is provided with a 
fold line 62 extending transversely thereacross and panels 54 are foldable 
along fold lines 64 extending transversely thereacross which are parallel 
to but offset from fold line 62 by an amount approximately equal to the 
thickness of blank 30. 
Each corner panel 40 is attached to central platform 32 along fold line 70 
and the corner panel comprises a pair of parallel crease or fold lines 72, 
73 extending transversely thereacross and spaced from each other about 
three times the thickness of blank 30. Another fold line 75 extends across 
the width of panel 40 spaced from lines 72, 73 so that when panel 40 is 
folded there are three panel subportions adjacent each other. Side flaps 
36 are separated from central platform 32 partly by a fold line 74 
extending from the corner of panel 40 and partly by a cut line 76 
collinear with fold line 74 wherein cut line 76 defines positioning tab 
78. An aperture 80 spaced from fold line 70 is provided for receiving 
therein positioning tabs 78. Each side flap 36 comprises a longitudinal 
fold line 86 and four spaced fold lines 88, 90, 92 and 94 extending 
transversely thereacross which define four rectangular panels 102, 104, 
108, 110 and a triangular panel 112 located adjacent panel 40. 
The various stages or steps in the assembly of a pallet base from blank 30 
are illustrated in FIGS. 2 to 9. The various panels comprising central 
flaps 34 are folded along fold lines 56, 64 and 62 to form a central side 
edge pallet support shown generally at 100 in FIGS. 4, 6 and 8. Glue or 
other adhesive is applied to the surfaces of panels 50 and 54 which 
contact each other when assembled as shown generally at 63 in FIG. 10. In 
addition, glue is applied along edges 67, best seen in FIG. 2, for bonding 
panels 54 to central platform 32. 
End flaps 36 are folded along longitudinal fold lines 86 and the resulting 
double thickness flap folded up along fold lines 74 to extend out of the 
plane of platform 32 as shown in FIGS. 4 and 5. Referring to FIGS. 9a, 9b 
and 9c (being a plan view), the two triangular panels 112 adjacent the 
corners of central platform 32 are overlapped together with the single 
thickness portions 113 overlapping as shown so that the two panel portions 
112 projecting across the corner portion of platform 32 overlap and fit 
together to form a double thickness corner reinforcement. 
Referring to FIGS. 6 to 8, the free ends of overlapped flaps 36 on either 
side of panel 40 are folded along fold lines 88, 90, 92 and 94 inwardly 
towards the corner of platform 32 and positioning tabs 78 are inserted 
into aperture 80 to form a unitary, hexagonally shaped corner support 120 
for the pallet base. The outer surfaces of the portions of end panels 102 
to which tabs 78 are integrally attached are coated with glue or other 
adhesive so that when the two end panels are placed adjacent each other 
they bond together, thereby securing corner support 120 in position. Panel 
40 is folded up and over the matched triangular panels 112 as best seen in 
FIG. 8. 
Referring specifically to FIG. 8, a central support member 130 comprises a 
strip of cardboard folded into a rectangular "figure eight" shape with the 
adjacent faces of the two end panels 132 glued together. Support member 
130 is glued to the bottom of central platform 32 in the middle thereof 
along an edge 134 of the support member. 
Referring to FIG. 11, when support members 120 at all the corners of the 
pallet base have been assembled and central support member 130 attached to 
the central portion of platform 32 to form an assembled pallet base 140, a 
load bearing tray 142 comprising sides 144 and base 146 may be secured to 
the pallet base as shown so that base 146 acts as the load bearing 
surface. Tray 142 may be secured to pallet base 140 by stapling the tray 
to support members 100 and 120, the staples being shown at 148. 
Alternatively, an adhesive may be used to attach tray 142 to support 
members 100 and 120. When pallet base 140 and tray 142 are coupled 
together, a pair of spaced passageways 152 are formed on each side of the 
assembled pallet which are for receiving therein the forks of a fork lift 
truck. Referring to FIG. 8, side edge support members 100 may be 
reinforced with a stack of cardboard, not shown, placed in rectangular 
aperture 154. 
In an alternative embodiment, pallet base 140 may be used as the pallet 
directly by turning over the base as shown in FIG. 8 without tray 142 
attached thereto so that support members 100, 120 and 130 directly engage 
the supporting surface. In this embodiment the load bearing surface is the 
bottom face of central platform 32 which is now raised above the 
supporting surface. 
An alternative embodiment of a unitary pallet base partially assembled from 
a blank 180 is shown in FIG. 12. Blank 180 is similar to blank 30 but with 
the following differences. Blank 180 is absent the triangular panels 112 
present in blank 30 and side flaps 182 are not folded in half along the 
longitudinal direction but are cut as shown to provide a securing tab 184. 
In addition, corner panels 186 are cut as shown to provide locating tabs 
188 on the free edges thereof spaced from the side edge of platform 32. An 
aperture 190 is located in each corner of platform 32 for receiving 
therein locating tab 188. Corner panels 186 are assembled to form corner 
support members 192. FIG. 13 shows the resulting assembled pallet base 194 
with tray 142 attached thereto. Tray 142 may be attached to base 194 by 
inserting securing tabs 188 through slots 196 located in base 146 and 
securing them to the surface of the base using glue or other adhesive, see 
FIG. 14. Alternatively, tabs 182 may be folded to underlay base 146 of 
tray 142 with the tray being secured using either adhesives, glue or 
staples 148, as shown in the lower corner of the assembled pallet is best 
seen in the cross section of FIG. 15. 
Referring to FIG. 16, a corner portion 210 of a blank of another 
alternative embodiment of a unitary pallet base constructed in accordance 
with the present invention is illustrated. The pallet base blank of which 
corner portion 210 forms a part is similar to blank 180 of FIG. 12 but 
with the following differences. Corner panels 212 are foldable along fold 
lines 214 which are located on either side of a rectangular positioning 
tab 216 defined by a cut line 218 extending between the inner ends of fold 
lines 214. An aperture 220 is located in the corner of central platform 32 
for receiving therein tab 216. End flaps 222 are provided with cut lines 
230 defining rectangular tab 232 and colinear fold lines 234 extending 
longitudinally along the centre of flap 222 for folding the flap when the 
pallet base is assembled, best seen in the sectional view of FIG. 18. FIG. 
17 illustrates a cross sectional view of assembled corner panel 212 to 
form a unitary corner support 240. The full use of panel 212 to provide 
the reinforced corner support 240 avoids needless waste of the paperboard 
material comprising the blank and avoids the use of a separate reinforcing 
or support member at the corners. It will be understood that the blank of 
FIG. 16 could also comprise tiangular panels similar to triangular panels 
112 in blank 30 of FIG. 1 in another embodiment of the invention. 
Referring now to FIG. 19, a corner portion 300 of a blank of another 
embodiment of a unitary pallet base constructed in accordance with the 
present invention is illustrated. The pallet base blank of which corner 
portion 300 forms a part is rectangular having a central deck or platform 
302 and integral side flaps 304 and 306 on either side of the corners. 
Flap 304 extends between cut lines 308 and 310 and is provided with a 
longitudinally extending double fold line 312. Flap 304 comprises three 
spaced fold lines 314, 316 and 318 extending transversely thereacross. 
Flap 304 comprises a panel 326 located between cut line 308 and fold line 
314. Flap 304 is separated from central portion 302 partly by a fold line 
320 extending from the corner of central platform 302 and partly by a cut 
line 322 collinear with fold line 320 wherein cut line 322 defines 
positioning tab 324 adjacent the end of side edge portion 304. 
Side portion 306 extends between cut lines 330 and edge 332 and is provided 
with a longitudinally extending single fold line 334. Side edge portion 
306 comprises four spaced fold lines 336, 338 and 340 extending 
transversely thereacross with edge 332 and fold line 342 defining an end 
panel 350 therebetween. Edge portion 306 is separated from central portion 
302 partly by a fold line 342 extending from the corner of central 
platform 302 and partly by a cut line 344 collinear with fold line 342 
wherein cut line 344 defines positioning tab 346. An aperture 348 is 
located in each corner of central platform 302 for receiving therein 
positioning tabs 322 and 346. 
The various steps or stages in the folding of side edge portions 304 and 
306 to form unitary corner support 356, best seen in FIGS. 20 and 21e, are 
illustrated in FIGS. 21a to 21e. Flap 306 is first folded along 
longitudinal fold line 334 with the outer longitudinal half of the flap 
folded to overlay the inner longitudinal half, see FIG. 21b. Referring to 
FIG. 21c, the resulting double thickness flap 306 is then folded upwardly 
along fold and cut lines 342 and 344 respectively followed by folding 
panel 350 inwardly toward central portion 302 along fold line 342. Flap 
304 is then folded upwardly along fold line 320 and cut line 322 after 
which the outer longitudinal half of this flap is folded along double fold 
line 312 with panel 350 being sandwiched between the outer and inner 
sections of panel 326. The folded flaps 304 and 306 are then folded 
inwardly toward the corner of central platform 302 as shown in FIG. 21d 
with the outer panels laying adjacent each other with positioning tabs 324 
and 346 inserted through aperture 348 to complete the assembly of corner 
support 356. 
Referring specifically to FIGS. 21e to 21g, a corner cube-shaped 
reinforcing member 360 is formed from a blank 362 comprising fold lines 
364, 366 and a cut line 368 collinear with fold line 366. Corner 
reinforcing member 360 is formed by folding blank 362 along the various 
fold and cut lines and gluing rectangular panel 370 to rectangular panel 
372. The outer surfaces of 374 and 370 are coated with a fast drying glue 
and corner member 360 is then inserted into assembled corner support 356 
to be glued to the adjacent panels of corner support 356. Triangular panel 
376 provides a flat support surface to which a tray (not shown) similar to 
tray 142 in FIG. 11 may be either glued or stapled. The assembled pallet 
base of which FIG. 21e forms a part includes side edge supports similar to 
support 100 shown in FIG. 8 and a central support member similar to 
support member 130 shown in FIG. 8. The side edge supports 100, corner 
supports 356 and central support 130 all extend out the plane of central 
load bearing platform 32 in the same direction and substantially the same 
distance as the corner support members. The pallet blank is fabricated of 
a stiff foldable material which is preferably a corrugated cardboard to 
provide a lightweight, recyclable and economic pallet. While tray 142 has 
been illustrated as being rectangular it will be appreciated that it could 
have an octogonal shape to match the octogonally shaped pallet base 
embodiments. 
Side edge support members 100 and central support member 130 in all the 
embodiments of the pallets disclosed herein may be dispensed with when the 
pallet is fabricated of a small enough size. As the pallet is scaled up in 
size, central support member 130 and side edge support members 100 are 
included to provide reinforcing strength in the centre and on the sides of 
the pallet. 
It will be appreciated by those skilled in the art that the pallet and 
pallet base comprising the unitary corner and side support members 
provides several advantages. First, the fact that the corner and side 
support members are of one piece construction with the support platform 
(i.e. a unitary structure) results in an improved pallet since the 
supports are not easily knocked off the pallet by the forks of a fork lift 
truck. Further, unitary corner supports may be fabricated having different 
geometries tailored for different load weights, compare pentagonal corner 
support 356 of FIG. 21(e) with hexagonal corner support 120 of FIG. 8. 
Rigidly attaching tray 142 to the unitary pallet base significantly 
improves the beam strength of the tray which provides a stronger pallet 
when, for example, the pallet is being lifted by a fork-lift truck. This 
improved strength prevents sagging of the sides of the pallet tray under 
load and as the pallet is lifted above the supporting surface. 
Another advantage of the unitary pallet base of the present invention is 
economic in nature relating to the fact that the pallet is constructed of 
one type of material and therefore dispenses with the need for reinforcing 
cores or cylinders separately attached to the pallet base. Further, corner 
and side supports forming part of the unitary base of the present 
invention may be reinforced in different ways depending on how the base 
blank portion is cut and folded and result in little wastage of cardboard 
material. The blanks illustrated in FIGS. 1, 16 and 21 illustrate three 
different ways of reinforcing the respective corner supports. The unitary 
pallet of the present invention, being fabricated of one type of material, 
is completely recyclable and does not require sorting or separating of 
different components as a prelude to recycling. 
While the pallet support base employing unitary corner and side support 
members forming the subject invention has been illustrated and described 
with respect to various embodiments, it will be appreciated that numerous 
variations of these embodiments may be made without departing from the 
scope of the invention described herein.