US 3640229 A
A pallet constructed from formed sheet material, such as a plastic sheet, having a generally planar load-supporting member from which downwardly depend hollow leg members and hollow stiffening members, the leg and stiffening members being of such configuration and dimensions and so disposed that sufficient rigidity is imparted to said load-supporting member that the latter is relatively undeformable under normal loads thereon.
Description (OCR text may contain errors)
D United States Patent 1151 3,640,229
Bell 5] Feb. 8, 1972  PALLET 3,433,184 3/1969 Addy ...108/53 3,467,032 9/1969 Rowlands et ...l08/5l  lg ggg 3,511,191 5/1970 Barry, Jr. et al. ..108/58  Filed: Oct. 6, 1969 Primary Examiner-Francis K. Zugel Assistant Examiner-Glenn O. Finch [211 Appl' 863391 Attorney-Hill, Sherman, Meroni, Gross & Simpson  U.S.Cl ..108/58  ABSTRACT  lnt.Cl.
A pallet constructed from formed sheet material, such as a  Field of Search ..l08/5 1-58 plastic Sheet, having a generally planar 10a d supporfing member from which downwardly depend hollow leg members  References (med and hollow stiffening members, the leg and stifiening members UNITED STATES PATENTS being of such configuration and dimensions and so disposed that sufiicient rigidity is imparted to said load-supporting Sullivan member that the latter is relatively undefo mable under nor- 3,228,358 H1966 Sepe et al. 108/58 ma] loads thereon 3,277,849 10/1966 Talbot ..108/58 3,359,929 12/1967 Carlson ..108/58 10 Claims, 8 Drawing Figures PALLET BACKGROUND OF THE INVENTION The invention is directed to a pallet structure for so supporting an object or a load of material that the pallet and load may be readily picked up by a fork lift truck and transported as desired.
Pallets of this type normally are constructed of wood and may weigh as much as 30 pounds or more. At the same time, such pallets are relatively costly as they must be manufactured by hand from wood stock, and are also quite bulky as they cannot be nested but must be stacked one upon the other. A further disadvantage of a wood pallet is the fact that being composed of a number of wooden pieces, deterioration takes place with age as well as a possible loosening up of the respective parts comprising the same whereby the pallet loses much of its original rigidity.
The present invention therefore is directed to a pallet structure which eliminates such disadvantages.
BRIEF SUMMARY OF THE INVENTION The present invention is directed to a pallet structure which is designed for fabrication from one or more pieces of sheet material such as sheet plastic in which the forming operation may take place, for example, by the utilization of vacuumforrning techniques in which the plastic sheet or sheets are heated and then subjected to the action of a vacuum, whereby the sheet material is drawn into the configuration of a mold or die to conform to the configuration of the latter, forming a substantially planar load supporting member having hollow legs and stiffening ribs integrally formed therewith as well as a reinforcing edge bead. The proportioning of the legs and stiffening ribs, as well as their locations and directions are so selected that the load supporting member of the pallet will have sufficient rigidity to be relatively undeformable under the normal loads which are to be carried by the pallet. This is achieved, in part, by disposing the ribs and legs along intersecting lines whereby the stifi'ening action of the legs and ribs is effected in transverse directions. The sidewalls of the leg and rib members preferably have at least a slight degree of divergence upwardly whereby the pallets are self nesting and thereby require a comparatively small amount of storage space.
Pallets constructed in accordance with the present invention may weigh as little as three pounds or more than 12 pounds, depending upon the loads which must be supported and therefore the thickness of the materials which must be employed. In addition to the advantages set forth above, the pallets are relatively indestructible, not being effected by the elements, substantially impervious to insects and the like and being of one-piece construction eliminates separation and loss of parts of the pallet as well as a loosening up of the components thereof.
BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings, wherein like reference characters indicate like or corresponding parts, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure, and in which:
FIG. 1 is a top plan view of a pallet embodying the present invention;
FIG. 2 is an end elevation of a pallet illustrated in FIG. 1
2 DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings and more particularly to FIGS. 1 through 3, the reference numeral 1 indicates generally a pallet constructed in accordance with the present invention which is formed from a generally rectangular sheet of plastic material, as forexample a polyethylene, which has a generally horizontally extending load supporting member 2 which is provided adjacent its periphery with a reinforced edge indicated generally by the numeral 3 of generally S-shaped transverse cross section. Extending downwardly from the load supporting member 2 are respective comer legs 4 and intermediate legs 4', the respective legs being integrally fonned from the material ofthe load supporting member 2. Also extending downwardly from the load supporting member 2 are a plurality of stiffening ribs 5 and 6, the ribs 5 extending generally transversely as viewed in FIG. 1 while the ribs 6 extend generally vertically as viewed in FIG. 1. As will be apparent from a reference to FIG. 2, both the legs 4, 4' and ribs 5, 6 are of hollow construction, being open at the top thereof and having sidewalls which diverge slightly in an upward direction, providing adequate draft during the vacuum-forming operation and at the same time providing a very rigid construction that will permit nesting of a plurality of pallets.
In the embodiment illustrated in FIG. 1 each of the leg portions 4'and 4' is provided with a plurality of outwardly extending generally vertically directed ribs 7 which are generally sernicylindrical in transverse cross section and have upwardly diverging sidewalls to provide the desired draft and facilitate nesting of the pallets. It will be noted that the legs and stiffening ribs extend along intersecting lines whereby the stiffening action is effected in generally alternating transverse directions resulting in a load supporting structure that will have relatively little deformation in a downward direction when subjected to the normal loads to be carried thereby.
Also contributing to the overall rigidity of the load supporting surface is the specific configuration of the peripheral edges of the load supporting member, the details of which are illustrated in FIG. 3. It will be noted that the edge portion, indicated generally by the numeral 3, comprises a generally inverted U-shaped portion indicated generally by the numeral 8 which is connected adjacent its outer edge with a U-shaped portion 9, the latter terminating at its upper edge in a horizontally extending portion 11, the outer edge of which terminates in a downwardly extending flange 12. In the embodiment illustrated,- the inverted U-shaped portion 8 has a flat top wall 13 and relatively flat downwardly diverging sidewalls l4 and 15, the latter wall being extended to form the adjacent sidewall of the U-shaped portion 9. This construction results in a relatively very stiff edge which strongly resists downward flexing, with the inverted U-shaped portion 8 forming a peripheral lip at the edge of the load supporting portion 2 tending to restrict sliding movement of a load on the member 2 and thus insure retention of such load thereon.
Assuming the pallet illustrated in FIG. 1 is fabricated from a sheet of polyethylene having a thickness of 0.080 inches, the finished pallet will have an approximate weight of six pounds. At the same time such a pallet will carry a load distributed over the load supporting member 2 of approximately 2,000 to 3,000 pounds. Likewise, if the pallet is made from a sheet of polyethylene having a thickness of 0.125 inches the finished pallet will have an approximate weight of 12 pounds and an approximate load carrying capacity of over 3,000 pounds. Where alighter weight pallet is desired, for somewhat lesser loads, a laminated sheet stock may be employed, for example such as illustrated in FIG. 4, in which two sheets 16 of polyethylene, each of 0.030 inch in thickness, are laminated to a central core 17 of plastic foam, of for example, 0.250 inch in thickness. A finished pallet fabricated from such stock will have an approximate weight of 3 pounds and an approximate load carrying capacity of over 3,000 pounds.
Tests have indicated that for the majority of applications where solid stock is employed the plastic sheet material will normally run in thickness from 0.080 inch to a maximum of approximately 0.150 inch. Obviously, depending upon the application, where a laminated structure is employed, the thickness of the sheet stock will normally run between 0.030 and 0.125 with the inner core normally being on the order of approximately 0.250. The total thickness of the stock forming the pallet thus would normally run from approximately 0.080 to 0.500 inch in thickness. However, in special applications other specific thicknesses may be employed.
FIGS. 5-8 illustrate additional arrangements of the supporting legs and stiffening ribs in accordance with the present invention, and again size, number and arrangements of the supporting legs and stiffening ribs will depend to a certain extent on the sheet stock employed, the load carrying capacity of the pallet, etc. Where thinner sheet material is employed, normally the span between stiffening ribs and between ribs and legs will normally be less than where a heavier stock is employed. Consequently, arrangements such as illustrated in FIGS. 1 and 5 would normally be employed in connection with pallets formed from lighter materials while arrangements such as illustrated in FIGS. 6, 7 and 8 would normally be employed with heavier stock.
It will also be appreciated that while the arrangements of FIGS. 5-8 do not illustrate the use of additional reinforcing ribs 7 on the supporting legs, such ribs may be applied to any one of such arrangements, the omission thereof being primarily for the purposes of clarity.
It will be appreciated from the above disclosure that I have provided a one-piece, very lightweight pallet which possesses a relatively high degree of rigidity even though it is made from comparatively thin sheet material, and which may be readily nested with like pallets to afford a considerable savings in storage space.
1. A pallet structure constructed of thin sheet material of substantially uniform thickness throughout, and having a generally planar load supporting member, a plurality of downwardly directed hollow legs formed from said sheet material and opening on the upper face of said load supporting member, said legs being symmetrically disposed with one leg disposed adjacent each comer of the load supporting member and intermediate legs disposed therebetween, said legs being so arranged that the fork of a lift truck may be inserted therebetween, a plurality of elongated downwardly directed hollow reinforcing ribs extending between such legs and opening on the upper face of said load-supporting member, the depth of said stiffening ribs being less than the depth of said legs to permit such a fork lift to pass under such stifiening ribs, said legs having reinforcing ribs which extend laterally outward from the associated leg sidewall and upwardly with the upper ends thereof opening on said load-supporting surface, a continuous reinforcing edge structure encircling said loadsupporting member and formed from said sheet material, said edge structure comprising a first portion, of inverted U-shape, in transverse cross section, having a pair of spaced sidewalls and a top wall connecting said sidewalls, the inner sidewall of said portion extending upwardly from said planar load-supporting member to provide a peripheral abutment encircling the same, the outer sidewall terminating at its lower edge in an outwardly directed bottom wall, the latter having at its outer edge an upwardly directed sidewall to form a second portion of U-shape in transverse cross section, with the intermediate side wall forming a part of both U-shaped portions.
2. A pallet structure according to claim 1, wherein the respective top, bottom and sidewalls of said U-shaped portions are substantially flat.
3. A pallet structure according to claim 1, wherein the outer sidewall of the second U-shaped portion is provided with a longitudinally extending reverse bend to form a longitudinally extending downwardly directed flange defining the extreme outer edge of the pallet structure.
4. A pallet structure according to claim 1 wherein said legs and stiffening ribs are generally rectangular in horizontal cross section and generally U-shaped in transverse vertical cross section.
5. A pallet structure according to claim 1, wherein said legs and stiffening ribs are disposed on intersecting lines.
6. A pallet structure according to claim 1, wherein said U- shaped portion of said edge structure adjacent said load-supporting member has a substantially flat top wall and relatively flat sidewalls which diverge from said top wall.
7. A pallet structure according to claim 1, wherein said pallet is made from sheet stock having an initial thickness of from approximately 0.030 inch to approximately 0.150 inch and has a maximum thickness of approximately 0.080 to 0.500 inch.
8. A pallet structure according to claim 7, wherein said sheet stock is a polyethylene.
9. A pallet structure according to claim 7, wherein said pallet is made from single thickness of sheet stock having an approximate thickness of from 0.080 to 0.150 inch.
10 A pallet structure according to claim 7, wherein said pallet comprises a laminated structure having two spaced outer plies of sheet plastic of at least 0.030 inch, between which is disposed a sheet of foam plastic having a thickness of approximately at least 0.250 inch.