Modular Nestable Pallet

Abstract

A pallet formed of nestable plastic modules each having four centrally located legs and four outwardly extending flanges, with each of the flanges having means for interlocking with the flanges of adjacent modules.

Description

This invention relates to an improved pallet construction. Usually pallets are provided by the manufacturer of the goods being shipped, and quite often the pallets are never returned to the manufacturer, thus the entire cost of the pallet is added to that of the product. If the pallets are returned there is also expense incident to this, and the weight of the pallet of course represents a portion of the transportation cost of the product.

Historically pallets have usually been made of wood. While wood pallets have adequate strength they are relatively heavy and thus add significantly to the expense of handling and transporting the goods. More importantly, the cost of wood itself has increased in recent years such that the cost of pallets becomes an increasing portion of the cost of goods. Pallets are often damaged during use and one of the advantages of wood is that it can be readily repaired; however, the cost of labor has increased to such an extent that wood is no longer nearly as practical as it use to be. Another disadvantage of wooden pallets is that even in storage they occupy considerable space, in that they must have sufficient depth to receive the fork of a forklift truck and in storage the pallets are stacked in a fashion that the height of one is added to the height of the next one.

Thus a need exists for a lightweight pallet construction which can be easily stored and is sufficiently inexpensive such that it can be treated as a disposable item if necessary but yet is sufficiently durable that it can be used countless times without appreciable wear. The present invention accomplishes such goals by providing a plastic pallet having a unique modular construction. While other plastic modules have been developed such as illustrated in U.S. Pat. No. 3,650,224 and 3,709.160, and one of these shows a modular arrangement, these and other prior art constructions appear to have certain drawbacks such that they have not become widely used.

The pallet module of the present invention includes an upper panel with four outwardly extending flanges. The flanges have means formed thereon which interlock with mating elements on the flanges of adjacent modules. Each module has centrally located legs which depend from the upper panel such that the tines of a fork of a forklift truck extend between the legs of adjacent modules beneath the overlapping interlocked flanges. Such entry may be made from any side. The legs are hollow with walls tapered so that the modules or assembled pallets may be conveniently nested during storage so as to minimize space requirements. The modules can be easily assembled to form the desired pallet size. Although the modules of a given pallet are securely interlocked, they can be separated if desired. The modules are thin walled and hence lightweight and inexpensive but yet provide adequate strength.

In a preferred form of the invention the interlocking means on the flanges includes a series of elongated slots on a pair of adjacent flanges and a series of similarly sized elongated lugs on the other two flanges. The slots include flexible tongue-like elements which snap into recesses in the lugs of an adjacent module to form a secure interlock. The flanges having the slots are slightly lower than the lugged flanges so that when the two modules are interlocked the upper surface of the assembled pallet is in a single plane.

For a more thorough understanding of the construction and the advantages of the invention refer to the following detailed description and drawings in which:

FIG. 1 is a perspective view of an assembled pallet employing nine modules and schematically illustrating the fork of a forklift truck in position to move the module;

FIG. 2 is an enlarged perspective view of the top of a single module;

FIG. 3 is an enlarged perspective view of the bottom of a single module;

FIG. 4 is an enlarged cross-section view of the overlapping flanges of a pair of adjacent modules as they are about to be assembled;

FIG. 5 is a view similar to that of FIG. 4 with the flanges interlocked;

FIG. 6 is a view similar to that of FIG. 5 with only a single row of lugs and slots being interlocked for a pair of adjacent modules;

FIG. 7 is a cross-sectional view of a pair of modules as shown in nested relations; and

FIG. 8 is a top plan view illustrating three modules assembled with the legs of one row of modules extending perpendicular to the legs of an adjacent row.

Referring first to FIG. 1, there is shown an assembled pallet made in accordance with the invention from a series of modules 10 preferably formed of a suitable plastic material which is easily molded and has considerable strength but with some flexibility. In the arrangement illustrated, nine identical modules are utilized creating a square pallet; however the pallet can be much larger or smaller as desired. A pair of tines 12 of the fork form a forklift truck are shown extending beneath the pallet to illustrate that operation. The broken lines 14 represent a load on the pallet.

Referring to FIGS. 2 and 3, it may be seen that an individual module comprises a flat rectangular upper panel having outwardly extending flanges 18, 19, 20 and 21 which extend throughout the lengths of the respective sides of the panel. The adjacent flanges 18 and 19 have their upper surfaces flush with the central panel 16 thus in effect forming a continuation of the panel. The flanges 20 and 21 have their upper surface slightly below the surface of the central panel 16 by an amount equal to the thickness of the flanges 18 and 19.

The module is supported by four hollow or cup-like legs 22 which depend from the central portion of the panel 16. Each leg 22 has a rectangular cross-section which opens to the upper surface of the panel 16. As best seen from FIGS. 3 and 7, the sidewalls of the legs taper or converge downwardly from the panel 16 such that the open upper end of each leg is larger than the lower end. This facilitates nesting of one module within another as illustrated in FIG. 7. The legs are joined near their upper ends by short gussets 24 which strengthen the structure and also limit the degree of nesting of modules so as to minimize any possibility of one module sticking within another. A hole 25 is formed in the bottom of each leg for drainage purposes.

The module flanges are formed with means for releasably interlocking with adjacent modules. The adjacent upper flanges 18 and 19 are identical and are provided with structure to fit within lock means on the lower flanges of adjacent modules, the lock structure on the lower flanges 20 and 21 also being identical. The upper flanges 18 and 19 are each provided with six elongated lugs which are individually numbered from 28 to 33 for flange 19, it being understood that the lugs on flange 18 are the same. As can be seen the lugs 28-33 extend generally parallel to the outer edge of the flange 19. The lugs are arranged in generally end-to-end relation in two similar rows, the lugs 28, 29 and 30 forming an outer row and the other three forming an inner row closer to the center of the module. Each lug is formed with an elongated recess 36 in one of its longer walls. The recess 36 is spaced upwardly from the bottom of the lug by a lip 37 and is bounded on its ends by end walls 38 and 39 as shown for example on lug 28 in FIG. 3. For convenience of molding, the recess 36 opens upwardly through the flange 19, thus forming a series of slits 40 which are visible from the upper side of the module, as best shown in FIG. 2. The end lugs 28, 30, 31 and 33 are identical having their recesses facing towards the center of the module while the middle lugs 29 and 32 have their recesses opening toward the outer edge of the flange.

The lugs on flange 19 are designed to mate with female interlocking means for an adjacent module, the interlocking means being like that shown on the lower flanges 20 and 21. Thus the cross-sectional views for FIGS. 4, 5 and 6 show the flange 19 in cooperation with a flange 21', which is identical to flange 21, however it is formed on the adjacent module 10' shown in FIG. 1. Flange 20 has the same interlocking means. The female means for receiving the lugs 28-33 includes six elongated slots 42-47 which extend generally parallel to the adjacent edge of the flange 21, with the slots 42, 43, 44 forming an outer row and the slots 45, 46 and 47 forming an inner row. Each slot includes a depending, vertically short wall 50 extending along one entire side of the slot, as may be seen in FIG. 2 for flange 21 and as shown at 50' for flange 21' in FIG. 4. Each slot is also formed with a second wall 52 which depends from its flange and extends at an angle toward the wall 50. The angle wall 52 may be seen for slot 46 in FIG. 2 and wall 52' is shown for slot 46' in FIG. 4. The wall 52 does not extend throughout the entire length of the slot instead its ends are spaced slightly from the ends of the slot as may be seen in FIG. 2. As a result, the wall 52 is actually supported in cantilever fashion and the material selected for the module is such that it enables the wall 52 to flex a limited amount and thus form a latch or locking tongue.

In use, the lugs on the upper flanges of one module mate with the slots on the lower flanges of an adjacent module. Consequently the slots and lugs are similarly spaced from each other so that the lugs will be properly aligned with the slots when the flanges are overlapped as shown in FIGS. 1, 4 and 5. Thus in considering a single module, the lugs 28 and 31 on the flange 19 are transversely aligned with the slots 42 and 45 on the opposite flange 21. The other lugs are similarly aligned with the other slots. Further, the length of each lug is slightly less than the length of each slot so that each lug will fit within a slot, as may be seen in FIG. 5. The width of each lug is slightly less than the maximum width of each slot at the upper entrance to the slot, as may be seen in FIG. 4. With flange 19 of module 10 positioned over flange 21 of the module 10' the lugs and slots can be aligned as shown in FIG. 4. The lugs partially fit within the slots without interference and then begin to engage the upper angular surface of the tongues 52'. Continued insertion force flexes each tongue outwardly and enables the lug lower end with its lip 37 to be inserted beyond the end of the tongue, which then enables the tongue to snap into the recess 36, as shown in FIG. 5.

The flanges are thus effectively locked together being restricted laterally by the walls of the lugs and the slots. In the vertical direction the flanges of course overlap to transmit force and the tongue and recess combinations hold the flanges together. Since the material has some flexibility the flanges can be forceably pried apart if desired. Because the recess and tongue combinations of the middle lugs and slots are oriented oppositely from that of the end lugs and slots on each flange, additional strength and stability is provided for the unit. Also note from FIG. 5 that the upper flange 19 completely overlaps the lower flange 21'; and since the lower flange is below the surface of its central panel 16' the upper surface of the central panel is flush with the upper surface of the flange 19.

In the arrangement of FIG. 5, both rows of lugs and slots are interlocked. Actually only a single row is necessary for strength purposes. Thus if it is desired to obtain a slightly wider pallet without using more modules, the upper flange can be positioned so that it overlaps only a portion of the lower flange such that the outer row of lugs in the upper flange mate with the outer row of slots in the lower flange as shown in FIG. 6. Note that the distance between the outer row of slots and the edge of flange 21' is approximately equal to the spacing between the rows of lugs so that the inner row of lugs on the flange 19 clears the outer edge of the flange 21 when the two modules 10 and 10' are assembled with the partial overlap shown in FIG. 6.

Referring to FIG. 3, it may be seen that four buttons 56' depend from the lower surface of the flanges 20 and 21 adjacent the corners of the flanges. The buttons extend below the lower surfaces of the lugs of the adjacent module when the lugs are positioned in the slots so as to protect the interlocking slots and lugs from being engaged by the fork of a forklift truck when the pallet is to be lifted by the truck.

In the assembled pallet shown in FIG. 1, the longer sides of the legs 22 all extend in the same direction. However with each module having two adjacent identical flanges, the pallet modules can be arranged so that alternate rows of modules have the legs oriented with the longer sides perpendicular to each other. Such an arrangement is illustrated in FIG. 8 wherein the legs of modules 60, 61 are oriented at 90.degree. from the legs of module 62. Also the modules can be arranged in checkerboard fashion wherein the legs of adjacent modules are oppositely arranged, i.e. the module 61 would be oriented with its legs parallel to those of module 62. These variations advantageously provide greater lateral stability.

It will be apparent from the foregoing that there are several other advantages of the plastic modular approach for pallet construction. The pallet itself can be made as large as desired by simply adding or subtracting modules. Also as indicated above some lateral side adjustability is obtained by interlocking one of two rows of lugs and slots in the flanges. The modules can be very lightweight and yet provide the necessary strength. The modules can be shipped assembled or unassembled. They require much less space than conventional panels because they can be readily nested either in the assembled or unassembled condition. Further the modules can be easily assembled at the shipping point. Plastic can of course be made in various colors which can also be an advantage for warehouse coding purposes. Although the modules are designed for frequent reuse, the plastic is sufficiently inexpensive that it may be practical in some operations to discard the modules after only a single usage. The plastic can of course by recycled. The legs on the pallet are sufficiently large such that the assembled pallet can be used in operations wherein loaded pallets are transported on conveyors and the legs will not become lodged between rollers on a conveyor.

Claims

What is claimed is:

1. A pallet module molded from plastic material comprising:

a generally rectangular upper panel;

leg means formed integral with the upper panel and depending from the central portion of the panel;

four flanges formed integral with the panel and respectively extending outwardly from the four edges of the panel supported in cantilever fashion; and

means formed on each of said flanges for overlapping and interlocking with flanges of similar modules such that a plurality of modules may be assembled to form a complete pallet, the distance between the outer edge of a flange and said leg means of said module being such that with two modules interconnected there is ample room between the leg means of adjacent modules for a tine of a forklift truck, said interlocking means permitting a complete pallet to be moved as a unit in any position, with or without a pallet load.

2. The pallet module of claim 1 wherein the upper surfaces of two adjacent flanges on the module are in generally the same plane as the upper surface of said panel, and the other two flanges are positioned in a plane below the upper surface of the panel by an amount approximately equal to the thickness of the upper flanges so that the upper flanges can overlap the lower flanges of an adjacent module when properly oriented and thus provide an upper pallet surface in approximately the same general plane.

3. The pallet module of claim 1 wherein said leg means includes one or more legs in the form of sockets which open upwardly and the walls of the legs taper slightly in a converging direction down from the upper panel so as to facilitate nesting of the modules during storage.

4. The pallet module of claim 3 wherein said leg means comprises four socket-like legs of generally rectangular crosssection with the legs being closely spaced and attached to the central portion of the upper panel, the depth of the legs being sufficient to readily accommodate the tines of the fork of a forklift truck in the space between the panel and a supporting surface beneath the legs.

5. The pallet module of claim 4 wherein the interlocking means formed on the flanges of a module are constructed so that the adjacent module can optionally be oriented with the longer side of its four legs extending generally parallel to the longer sides of the four legs of an adjacent module or perpendicular to the longer sides on the four legs of an adjacent module.

6. A pallet formed by a series of interconnected modules, each of said modules being molded from plastic material and having:

a generally rectangular upper panel with flanges formed integral with the upper panel extending outwardly from the four edges of the panel supported in cantilever fashion;

means formed on each of the flanges for interlocking with flanges of adjacent modules; and

leg means formed integral with the upper panel on each module and depending from the central portion of the upper panel so that the assembled pallet has a plurality of spaced leg means, the spacing between the leg means of adjacent modules being sufficient to receive one tine of the fork of a forklift truck, the interlocking means permitting the pallet to be moved as a unit in any position, with or without a pallet load.

7. A pallet module molded from plastic material comprising an upper panel with outwardly extending flanges and means formed on the flanges for interlocking with flanges of similar adjacent modules, said interlocking means comprising one or more lugs depending from the lower surface of one of said flanges and one or more slots formed in an adjacent one of said flanges, said lugs being sized to be received into the slots in a flange of a similar adjacent module, said lug and slot include means for retaining the lug within the slot once the lug is received in the slot, said slot includes a tongue forming a wall of the slot and depending from the lower surface of its flange in cantilever fashion, with the tongue extending inwardly toward the center of the slot, said tongue being slightly flexible so that it may be forced aside by the lugs when the lug is inserted into the slot, said lug having a recess in one of its sidewalls spaced upwardly from the lower surface of the lug and positioned to receive the tongue of the slot after the lug means has been inserted into the slot, so as to retain the lug in the slot.

8. A pallet module molded from plastic material comprising an upper panel with outwardly extending flanges and means formed on the flanges for interlocking with flanges of similar adjacent modules, said interlocking means comprising one or more lugs depending from the lower surface of one of said flanges and one or more slots formed in an adjacent one of said flanges, said lugs being sized to be received into the slots in a flange of a similar adjacent module, said lug has an elongated shape extending generally parallel to the outer edge of the flange.

9. The module of claim 8 wherein said lugs include three elongated lugs extending in a row generally parallel to the outer edge of the flange on which the lugs are formed, each of the lugs having an elongated recess formed in one wall of the lug and spaced upwardly from the lower edge of the lug, said slots including three elongated slots extending in a row generally parallel to the outer end of the flange in which the slots are formed, each of the slots including a tongue forming an edge of the slot and extending below the lower surface of its flange, the tongue being oriented at an acute angle with the flange and extending inwardly towards the center of its slots, the tongue and the recess being sized and positioned such that when the lugs on the flange of one module are inserted into the slots on the flange of an adjacent module the tongues are snapped into the recesses in the lugs to attach the modules together.

10. The module of claim 9 wherein the middle lug of said three lugs has its recess located on the wall if its lug which is opposite to the location of the recesses in the two outer lugs, and the middle tongue extends along the edge of its slot which is opposite to that of the tongues for the two outer slots.

11. The module of claim 9 wherein a second row of lugs is formed adjacent the first mentioned row of lugs and a second row of slots is formed adjacent the first mentioned row of slots, said slots and lugs being so positioned that when adjacent modules are to be attached to each other a single row of lugs and slots may be interlocked or both rows of lugs and slots may be interlocked thus providing a lateral adjustment.

12. A pallet module molded from plastic material comprising an upper panel with outwardly extending flanges and means formed on the flanges for interlocking with flanges of similar adjacent modules, said interlocking means comprising one or more lugs depending from the lower surface of one of said flanges and one or more slots formed in an adjacent one of said flanges, said lugs being sized to be received into the slots in a flange of a similar adjacent module, the flanges having said slots are formed with a plurality of buttons depending from the flange lower surfaces a distance such that the lower surfaces of the buttons are below the lower surfaces of the lugs of an adjacent module when the lugs are positioned in the slots so that when the forks of a forklift truck extend between the adjacent modules the fork will engage the buttons rather than the interlocking slots and lugs.

13. A pallet module molded as an integral structure from plastic material comprising:

a generally rectangular upper panel;

four legs extending downwardly from the central portion of the upper panel, the height of the legs being greater than the vertical thickness of the fork of a typical forklift truck, said legs having a generally rectangular cross-section formed by walls which taper inwardly in a downwardly direction so that the upper ends of the legs are larger than the lower ends of the legs so as to facilitate nesting of the modules during storage;

four flanges extending outwardly from the upper panel respectively from the four edges of the panel, two adjacent flanges having their upper surfaces being spaced downwardly from the upper surface of the panel in an amount equal to the individual thickness of the other two flanges so that when the upper flanges are positioned over the lower flanges of an adjacent module they are flush with the upper panel of the adjacent module; and

means formed on said flanges for interlocking with flanges of adjacent modules to create a pallet formed of a series of modules, said interlocking means including two rows of three slots formed in the lower flanges and extending generally parallel to the outer edges of their respective flange, the upper flanges of said module each having two rows of three elongated lugs which depend from their flanges, with the rows extending generally parallel to the outer edges of their flanges, said lugs being slightly shorter in length than said slots and said lugs being slightly smaller in width than the upper width of said slots, said lugs being spaced similar to said slots such that the lugs of one flange are transversely aligned with the slots of the flange on the opposite side of the module.

14. The module of claim 13 wherein said lugs each have an elongated recess formed on one of the longer walls of the lug and spaced upwardly from the lower edge of the lug, and each of said slots has one of its longer sides defined by a wall depending from the flange and having its opposite side defined by an elongated tongue which depends from the flange at an angle towards the center of its slot.

15. The module of claim 14 wherein the middle slots in each of said rows of slots have the orientation of their walls and tongues reversed from that of the end slots of said rows of slots, and the recesses in the middle lugs in each of said rows of lugs are oriented opposite to that of the recesses of the end lugs of said rows of lugs.

16. The module of claim 15 wherein the tongues of the end slots in each of said rows of slots extend inwardly toward the module legs, and the recesses in the end lugs of each of said rows of lugs open inwardly toward the module legs.

17. The module of claim 16 wherein the recesses on said lugs open to the upper surface of their respective flanges thus forming two rows of slits in the upper surface of their respective flanges.

18. The module of claim 14 including means depending from the lower surface of the lower flanges below the lower edges of the tongues so as to protect the tongues from damage by the fork of a forklift truck.