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Publication numberWO1990009325 A1
Publication typeApplication
Application numberPCT/US1990/000515
Publication date23 Aug 1990
Filing date30 Jan 1990
Priority date13 Feb 1989
Also published asCA2000871A1
Publication numberPCT/1990/515, PCT/US/1990/000515, PCT/US/1990/00515, PCT/US/90/000515, PCT/US/90/00515, PCT/US1990/000515, PCT/US1990/00515, PCT/US1990000515, PCT/US199000515, PCT/US90/000515, PCT/US90/00515, PCT/US90000515, PCT/US9000515, WO 1990/009325 A1, WO 1990009325 A1, WO 1990009325A1, WO 9009325 A1, WO 9009325A1, WO-A1-1990009325, WO-A1-9009325, WO1990/009325A1, WO1990009325 A1, WO1990009325A1, WO9009325 A1, WO9009325A1
InventorsRobert L Frenkel, G Robert Mitchell, John S Todor Jr, Ferdinand Weits
ApplicantCoors Co Adolph
Export CitationBiBTeX, EndNote, RefMan
External Links: Patentscope, Espacenet
Slip pallet with a cushioning effect
WO 1990009325 A1
Abstract
A slip pallet (2) formed as a square or rectangular sheet of a plastic material having a central body portion (81) on which a load, such as an array of loaded cardboard boxes, is supported and a plurality of lip portions (14) extending outwardly and upwardly from the central body portion (81) wherein at least the central body portion (81) is provided with a plurality of spaced apart dimples (20) formed in the top surface of the central body portions so that a plurality of spaced apart projections (22) extend downwardly from the bottom surface of the central body portion to provide a cushioning support for the load and wherein at least a portion of each projection (22) is a segment of a sphere.
Claims  (OCR text may contain errors)
WHAT IS CLAIMED IS:
1. A shock absorbing pallet comprising:
a sheet of single ply plastic material having a thickness of between about 0.025 and 0.125 of an inch and a stiffness measurement in the range of between about 120,000 and 180,000 psi as
determined by ASTM specification D 790B;
said sheet having opposite pairs of parallel edges defining a central body portion for
supporting a load;
an integral lip portion extending outwardly and upwardly from at least one of said edges;
said central body portion having a top surface and a bottom surface;
a plurality of spaced apart dimples in said top surface forming a plurality of spaced apart projections on said bottom surface thereof so that said dimples will provide a cushioning effect whenever an additional force is placed on said load; and
said top and bottom surfaces being generally planar except for said dimples and projections.
2. A pallet as in claim 1 wherein:
said at least one lip portion has a top surface and a bottom surface; and
a plurality of spaced apart dimples in said top surface of said at least one lip portion forming a plurality of spaced apart projections on said bottom surface thereof.
3. A pallet as in claim 1 wherein:
said plurality of space apart dimples extend in spaced apart parallel rows having the same number of dimples and which rows are parallel to one pair of said opposite pairs of parallel edges and perpendicular to the other pair of said opposite pairs of parallel edges.
4. A pallet as in claim 3 wherein:
said at least one lip portion has a top surface and a bottom surface; and
a plurality of spaced apart dimples in said top surface of said at least one lip portion forming a plurality of spaced apart projections on said bottom surface thereof.
5. A pallet as in claim 4 wherein:
each of said dimples in said at least one lip portion is in alignment with one of said spaced apart parallel rows of dimples.
6. A pallet as in claim 5 wherein said at least one lip portion comprises:
at least three lip portions.
7. A pallet as in claim 1 wherein:
each of said dimples having a shape corresponding to a segment of a sphere having one portion thereof generally parallel to said top surface.
8. A pallet as in claim 7 wherein:
said plurality of dimples are located on spaced apart centers of between about 0.750 and 1.50 inches with each circular segment thereof having a radius of between about 0.1875 and 0.563 inch;
each projection has a depth of between about 0.094 and 0.281 inch from said bottom surface to the crest of said projection; and
said dimples have a density of between about 0.75 and 2.00 per square inch.
9. A pallet as in claim 8 wherein:
the surface areas of the outer surfaces of said projections comprises between about 60 and 95 per cent of the surface area of said top surface of said central body portion.
10. A pallet as in claim 1 wherein:
each of said projections having a shape corresponding to a frustum of a sphere wherein the planes forming said frustum are parallel to said bottom surface.
11. A pallet as in claim 1 and formed in
accordance with the following formula:
deflection y = APR2
16πD
where D = Et3
12(1-⋎)
R = outer radius of the dimple where ⋎ = poissons ratio
A - is from the following table
* Λ
E = Young's modulus of elasticity
t = final thickness where final thickness t = initial thickness (F) x
where
F = flat sheet thickness
R = outer radius of the dimple
d = distance R is spaced from centerline of F l = diameter of the bottom portion of the segment of the sphere
c = circumference of the bottom portion of the
segment of the sphere
for a semi-sphere d = 0 and D = 2R
The conventional formula for P which the load
distribution, illustrated in Fig. 7, is:
P = load lbs/ft2 = load (C2 ) = lbs./dimple (12"/C) (12"/C) 144
where C is space between centers of the dimple.
Description  (OCR text may contain errors)

SLIP PALLET WITH A CUSHIONING EFFECT

Field of the Invention

This invention relates generally to pallets for use in supporting loads during shipment or storage of materials and more specifically to a slip pallet with a cushioning effect for a load supported thereon, such as an array of cardboard boxes holding beverage

containers.

Background of the Invention

Plastic slip pallets, such as those described in U.S. Patent Nos. 3,776,145; 3,850,116 and 4,042,127, have been used for ease of storage and handling of a load of boxes supported thereon in a warehouse, a manufacturing facility and during shipment by rail or by truck. A plastic slip pallet has a lip means adapted to be gripped by a lift truck and held in tension while slipping a platen, or spatula-like member, of the lift truck under the plastic slip pallet. The platen then lifts the plastic slip pallet and the boxes supported thereon and transports them to a desired location where the slip pallet and the boxes are pushed off the platen. A recent development in plastic slip pallets is disclosed in U.S. Patent No. 4,507,348 to Nagata et al. The slip pallet in Nagata et al. comprises a support member comprising an interlining core sandwiched between and secured to two liners and has a flap portion continuous to the support member through a bending portion in which the

interlining core and the two liners are compressed together and fused into one continuous layer to provide a hinge effect. While the corrugated slip pallet of Nagata et al. does provide a cushioning effect, it is expensive to manufacture. Brief Description of the Invention

This invention provides a slip pallet with a cushioning effect comprising a sheet of single ply plastic material having a plurality of spaced apart dimples formed therein to provide a cushioning effect while retaining its load supporting properties.

In the preferred embodiment of the invention, the slip pallet is formed from a single ply of plastic material, such as polypropylene or high density

polyethylene, having a thickness of between about 0.040 and 0.125 inch and a stiffness measurement in the range of 120,000 to 180,000 psi as determined by ASTM

specification D 790B. The slip pallet has opposite pairs of generally parallel edges to define a central body portion for supporting a load, such as an array of cardboard boxes holding filled beverage containers. The central body portion originally has a generally planar top surface and a generally planar bottom surface. A plurality of spaced apart dimples are formed downwardly from the top surface so as to form a plurality of spaced apart projections extending

downwardly from the bottom surface. The dimples are generally spherical segments having an outer radius of between about 0.1875 and 0.563 inch and a depth from the bottom surface to the crest of the dimple of between about 0.094 and 0.281 inch so that the projections formed thereby have outer surfaces which are segments of a sphere. The projections have a density of between about 0.75 to 2.00 per square inch and a surface area of between about 60 to 95 per cent of the entire surface area of the top surface. At least one integral lip portion extends outwardly and upwardly from one of the edges. Suitable materials for forming the plastic slip pallet are set forth in U.S. Patent 3,776,145 from Column 8, Line 43, to Column 9, Line 15. The preferred embodiment of this invention uses a copolymer of polypropylene marketed by Hercules Powder Co. of Wilmington, Delaware, under the trade designation pro-foxR 8623. Brief Description of the Drawings

An illustrative and presently preferred embodiment of the invention is shown in the accompanying drawings in which:

Fig. 1 is a perspective view of the preferred embodiment of the invention;

Fig. 2 is a cross-sectional view taken on the line 2-2 of Fig. 1;

Fig. 3 is an enlarged cross-sectional view similar to a portion of Fig. 2 but with no load supported thereon;

Fig. 4 is an enlarged cross-sectional view similar to Fig. 3 but with a load supported thereon;

Fig. 5 is an enlarged cross-sectional view of another modification of the invention but with no load supported thereon; and

Figs. 6 and 7 are illustrations for use with the formula set forth in the specification. Detailed Description of the Invention

The preferred embodiment of the invention is illustrated in the drawing and comprises a slip pallet 2 formed from a single ply of plastic material such as polypropylene or a high density polyethylene or other materials having similar characteristics. The plastic material has a thickness between about 0.040 and 0.125 inch and a stiffness measurement in the range of

120,000 to 180,000 psi and preferably about 160,000 psi as determined by ASTM specification D 790B. The slip pallet 2 has opposite pairs of generally parallel edges 4 and 6 to define a central body portion 8 originally having a generally planar top surface 10 and a

generally planar bottom surface 12. Integral lip portions 14 are formed in a conventional manner and extend outwardly and upwardly from the generally parallel edges 4 and one of the generally parallel edges 6. If desired, the slip pallet 2 may have diagonally cut corners 16 preventing edges 4 and 6 from intersecting.

A plurality of dimples 20 are formed in the top surface 10 so that a plurality of projections 22 extend downwardly from the bottom surface 12. The dimples 20 have an inner surface 24 that is a segment of a sphere and the projections 22 have an outer surface 26 which is a segment of a sphere. The radius of the outer surface 26 is between about 0.1875 and 0.563 inch and the projections 22 have a depth, measured from the bottom surface 12 to the crest of the projection 22, of between about 0.094 and 0.281 inch.. The centers for the spheres of the outer surfaces 26 are located above the top surface 10 a distance equal to one-half of the radius minus the thickness between the planar portions of the top and bottom surfaces. In accordance with this invention, the depth of each projection 22 from the bottom surface 12 will be about one-half the radius of the outer surface 26. The dimples 20 have centers which are spaced apart a distance of between about 0.75 and 1.50 inches and have a density of between about 0.75 and 2.00 per square inch and a surface area of between about 65 and 90 per cent of the top surface 10. As illustrated in Fig. 1, the dimples 20 preferably extend in spaced apart parallel rows which rows are parallel to the opposite parallel edges 4 and

perpendicular to the opposite parallel edges 6. There are no dimples 20 in the lip portions 14 integral with the opposite edge portions 4, but there are dimples in the lip portion 14 integral with the one edge 6.

In Fig. 3, there is illustrated one dimple 20 of a central body portion 8 wherein the thickness of the plastic sheet between dimples 20 is about 0.051 inch. The outer surface 26 of each of the dimples 20 has a radius of about 0.250 inch and are on spaced apart centers of about 1.00 inch. The center for the radius is located about 0.074 inch above the top surface 10. Each projection 22 has a depth of about 0.125 inch from the bottom surface 12 to the crest of the projection 22. In Fig. 4, there is illustrated the same dimple 20 when a load of about 6,000 pounds per square foot is being supported by the central body portion 8. The depth of the projection 22 has been decreased by about 0.042 inch so that the dimple 20 still has a depth of about 0.083 inch and is fully capable of supporting greater loads. A slip pallet 2 having the dimples 20 as described above is capable of supporting loads up to about 10,000 pounds per square foot and still providing a cushioning effect.

In some instances, the use of a slip pallet 2 as illustrated in Figs. 1 - 4 present some problems in that there is a tendency for the slip pallet 2 to slide when being supported on a platen as illustrated in U.S. Patent No. 3,776,145. In Fig. 5, there is illustrated a slip pallet 30 where a portion 32 of the outer surface 24 is relatively planar so that the portion 34 of the inner surface 26 is also relatively planar so as to provide a greater surface area for contact with the surface of the platen so as to provide greater

frictional forces to prevent the sliding of the slip pallet 30 on the platen. The arcuate outer surface 36 is a frustum of a sphere having a radius of between about 0.185 and 0.563 inch and wherein the center of the sphere is located a distance above the top surface 10 equal to one-half the radius minus the thickness between the planar portions of the top and bottom surfaces. The portion 32 has a depth of between about 0.061 and 0.248 inch and the planar surface 32 has a diameter of between about 0.1875 and 0.563 inch. In a preferred embodiment of the dimple of Fig. 5, the surface 32 has a diameter of about 0.25 inch and a depth of 0.092 inch. The arcuate outer surface 36 has a radius of about 0.25 wherein the center 38 of the sphere is located 0.074 inch above the bottom surface 12.

When the slip pallets of this invention are used in the shipment by truck or rail of filled beverage containers packed in boxes, the weight on each slip pallet is between about 2,100 and 2,600 pounds per square foot. In normal practice, one slip pallet is loaded on top of another slip pallet so that the load on the bottom slip pallet is between about 4,200 and 5,200 pounds per square foot. During shipment, the truck or rail car may periodically place additional loads on the slip pallets. During such additional loads, the projections will be depressed in an amount relative to the additional load, but after the

additional load has been removed, the projections will resile to their configuration prior to the additional load.

The above-described preferred embodiment is based on a load on the bottom slip pallet of between about 4,200 and 5,200 pounds per square foot. The specific construction of the slip pallet with dimples for any desired load may be calculated i

n the following manner.

The conventional formula for the deflection of a sphere, illustrated in Fig. 6, wherein the dimple has been inverted for explanation purposes only, is:

deflection y = APR2

16πD

where D = Et3

12(1-⋎)

R = outer radius of the dimple where ⋎= poissons ratio

A - is from the following table

*

E = Young's modulus of elasticity

t = final thickness

where final thickness t = initial thickness (F) x T

where

F = flat sheet thickness

R = outer radius of the dimple

d = distance R is spaced from centerline of F l = diameter of the bottom portion s of the segment of the sphere

c = circumference of the bottom portion s of the

segment of the sphere for a semi-sphere d = 0 and D = 2R

The conventional formula for P which the load

distribution, illustrated in Fig. 7, is:

P = load lbs/ft2 = load (C2 ) = lbs./dimple (12"/C) (12"/C) 144

where C is space between centers of the dimple.

While illustrative and presently preferred embodiments of the invention have been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
DE2625346A1 *4 Jun 197615 Dec 1977Rockwell International CorpFlexibles bauteil
US3199468 *23 Apr 196210 Aug 1965Charles M SullivanNestable pallets
US3231454 *14 Apr 196125 Jan 1966Cadillac ProductsCushioning material
US3545249 *8 Apr 19688 Dec 1970Dayton Reliable Tool & Mfg CoDimple and method of forming same
US3776145 *27 Mar 19724 Dec 1973Best Quality Plastics IncSlip pallet
US3850116 *17 Sep 197326 Nov 1974Bqp Ind IncSlip pallet reinforced with fillers
US3892902 *4 Dec 19721 Jul 1975Preco Ind LtdPlastic panel pad construction for spacing concrete panels
US4042127 *30 Oct 197516 Aug 1977Adolph Coors CompanySlip pallet and divider sheet
US4507348 *5 Apr 198326 Mar 1985Mitsui Petrochemical IndustriesCorrugated board-like sheet made of synthetic resin
US4562718 *8 Mar 19847 Jan 1986Precision Tool & Gauge Pty. Ltd.Pallet and method of production
Classifications
International ClassificationB65D19/36
Cooperative ClassificationB65D19/36
European ClassificationB65D19/36
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