Plastic Pallet with Bidirectional Intersecting Reinforcing Elements and Corresponding Manufacturing Methods

Abstract

A pallet (100) having a unitary plastic body (102) with at least four legs (104a), and including two sets of channels (106, 108) extending parallel to its two dimensions D1 and D2. The pallet also includes a first set of elongated reinforcing elements (110) deployed within channels (106) and a second set of elongated reinforcing elements (112) deployed within channels (108). The first set of elongated reinforcing elements (110) have apertures (114) positioned so as to align with channels (108). Apertures (114) are sized and shaped to receive elongated reinforcing elements (112) passing through the apertures, resulting in an inter-engagement of elements (110) and (112) at multiple cross-over locations (116) as they extend through the pallet.

Claims

1. A pallet comprising for supporting a load above an underlying surface: (a) a unitary plastic body having a rectangular perimeter with a first dimension and a second dimension, and having at least four legs for supporting said unitary plastic body above the underlying surface, said unitary plastic body including a first plurality of channels extending parallel to said first dimension and open to at least one edge of said unitary plastic body, and a second plurality of channels extending parallel to said second dimension and open to at least one edge of said unitary plastic body; (b) a first set of elongated reinforcing elements deployed within said first plurality of channels and extending along a majority of said first dimension, said first set of elongated reinforcing elements having apertures aligned with said second plurality of channels; and (c) a second set of elongated reinforcing elements deployed within said second plurality of channels and passing through said apertures in said first set of elongated reinforcing elements, said second set of elongated reinforcing elements extending along a majority of said second dimension.

2. The pallet of claim 1, wherein said unitary plastic body includes a deck for supporting the load, said deck spanning said first and second dimensions.

3. The pallet of claim 1, wherein said legs are hollow legs configured to allow nesting of part of the legs of another similar pallet within said hollow legs when similar pallets are stacked.

4. The pallet of claim 1, wherein said first set of elongated reinforcing elements have a rectangular cross-section.

5. The pallet of claim 1, wherein said first set of elongated reinforcing elements have an I-beam cross-section.

6. The pallet of claim 1, wherein said second set of elongated reinforcing elements have a circular cross-section.

7. A method for assembling a pallet for supporting a load above an underlying surface, the method comprising the steps of: (a) providing a unitary plastic body having a rectangular perimeter with a first dimension and a second dimension, and having at least four legs for supporting said unitary plastic body above the underlying surface, said unitary plastic body including a first plurality of channels extending parallel to said first dimension and open to at least one edge of said unitary plastic body, and a second plurality of channels extending parallel to said second dimension and open to at least one edge of said unitary plastic body; (b) inserting a first set of elongated reinforcing elements along said first plurality of channels so as to extend along a majority of said first dimension, said first set of elongated reinforcing elements having apertures aligned with said second plurality of channels; and (c) inserting a second set of elongated reinforcing elements along said second plurality of channels so as to pass through said apertures in said first set of elongated reinforcing elements and to extend along a majority of said second dimension.

8. The method of claim 7, wherein said unitary plastic body includes a deck for supporting the load, said deck spanning said first and second dimensions.

9. The method of claim 7, wherein said legs are hollow legs configured to allow nesting of part of the legs of another similar pallet within said hollow legs when similar pallets are stacked.

10. The method of claim 7, wherein said first set of elongated reinforcing elements have a rectangular cross-section.

11. The method of claim 7, wherein said first set of elongated reinforcing elements have an I-beam cross-section.

12. The method of claim 7, wherein said second set of elongated reinforcing elements have a circular cross-section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:

[0017] FIG. 1A is an upper isometric view of a pallet, constructed and operative according to an embodiment of the present invention, employing bidirectional intersecting reinforcing elements;

[0018] FIG. 1B is a lower isometric view of the pallet of FIG. 1A;

[0019] FIG. 1C is a cross-sectional view taken on the plane I-I of FIG. 1A;

[0020] FIG. 1D is a cut-away isometric view of the pallet of FIG. 1A cut along the plane I-I;

[0021] FIG. 2 is an exploded view of the pallet of FIG. 1A illustrating the intersecting reinforcing elements prior to insertion, employing rectangular reinforcing elements along a first dimension and round reinforcing elements along a second dimension;

[0022] FIG. 3 is an exploded view similar to FIG. 2, illustrating a variant implementation with rectangular reinforcing elements along both the first dimension and the second dimension;

[0023] FIG. 4 is an exploded view similar to FIG. 2, illustrating a variant implementation with I-beam reinforcing elements along the first dimension and round reinforcing elements along the second dimension; and

[0024] FIG. 5 is an exploded view similar to FIG. 2, illustrating a variant implementation with rectangular reinforcing elements along the first dimension and I-beam reinforcing elements along the second dimension.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The present invention is a plastic pallet with bidirectional intersecting reinforcing elements and corresponding manufacturing methods.

[0026] The principles and operation of pallets and methods according to the present invention may be better understood with reference to the drawings and the accompanying description.

[0027] Referring now to the drawings, FIGS. 1A-1D and 2 illustrate a pallet, generally designated 100, constructed and operative according to the teachings of a first embodiment of the present invention, for supporting a load above an underlying surface. In general terms, the pallet includes a unitary plastic body 102 having a rectangular perimeter with a first dimension D1 and a second dimension D2, and having at least four legs 104a for supporting the unitary plastic body above the underlying surface. The unitary plastic body 102 also includes a first plurality of channels 106 (best seen in FIG. 2) extending parallel to the first dimension D1 and open to at least one edge of the unitary plastic body 102, and a second plurality of channels 108 (best seen in FIG. 2) extending parallel to the second dimension D2 and open to at least one edge of the unitary plastic body 102. The pallet also includes a first set of elongated reinforcing elements 110 deployed within channels 106 and extending along a majority of the first dimension D1 and a second set of elongated reinforcing elements 112 deployed within channels 108 and extending along a majority of the second dimension D2. Elongated reinforcing elements 110 have apertures 114 (best seen in FIG. 2) positioned so as to align with channels 108. Apertures 114 are sized and shaped to receive elongated reinforcing elements 112 passing through the apertures, resulting in an inter-engagement of elements 110 and 112 at multiple cross-over locations 116 as they extend through the pallet, best seen in FIG. 1B.

[0028] The term channel is used herein in the description and claims to refer to any structure which defines an insertion path for the corresponding reinforcing element and, after insertion, holds the reinforcing element in known spatial relation to unitary plastic body 102. Thus, channels 106 and/or 108 do not need to be continuous along the length of the reinforcing elements. Thus, in the example illustrated here in FIG. 1B, various portions of the length of the reinforcing elements 110 and 112 are actually exposed to the underside of the pallet. Furthermore, the channels do not need to fully envelope the reinforcing elements at any particular position. In the schematic illustrations shown here, the channels are closed channels which fully envelope the reinforcing elements in the peripheral frame region, as would be formed by moving cores of a mold. In order to facilitate motion of cores in two perpendicular directions, most or all of the cross-over locations 116 where the reinforcing elements inter-engage are preferably exposed so that one of the cores can stop short of the cross-over regions. Alternative implementations of the channels may employ opposing shut-off features defining lower and upper regions of the channel at distinct positions along the length of the reinforcing elements, without the channels fully enclosing the reinforcing elements at any point. Combinations of these techniques may also be used, for example, to facilitate the use of shorter moving cores.

[0029] The use of a unitary plastic body forming a rectangular outer frame together with inter-engaged bidirectional elongated reinforcing elements provides a high-rigidity pallet structure whose rigidity and structural strength are largely independent of the mechanical properties of any plastic structure internal to the frame. As a result, the quantity of plastic used for the middle portion of the pallet can be reduced or even eliminated, thereby reducing the total quantity of flammable material present in the pallet, and facilitating meeting the requirements of flammability regulations.

[0030] In certain cases, depending on the type of load to be carried, the pallet may be implemented without any central plastic structure, instead employing the outer plastic frame alone to support the load and/or allowing the load to rest directly on one or both of the sets of reinforcing elements. In the particularly preferred case illustrated here, unitary plastic body 102 further includes a central deck-forming structure 118 which, together with the top surface of the outer frame, forms a deck for supporting the load which spans the first and second dimensions D1 and D2. The central deck-forming structure 118 is preferably implemented as a lightweight structure which does not require significant load-bearing capacity, instead spreading the load and transferring it to the first set of elongated reinforcing elements 110 and/or preventing small objects from falling through the spaces between the reinforcing elements. Thus, the structure can be a relatively thin layer, and without support ribs. In the particularly preferred example illustrated here, the central deck-forming structure 118 is formed with a set of ridges running perpendicular to the first set of reinforcing elements 110, which help to provide enhanced directional rigidity of this surface between adjacent reinforcing elements. Even with these ridges, the central deck-forming structure 118 remains thin compared to conventional load-bearing central deck structures, typically not exceeding a total thickness of about 4 millimeters, and more preferably no more than 2 millimeters.

[0031] The representations of pallet 100 are shown only schematically, without any attempt to show details of the plastic molding structures, such as arrangements of spaced ribs etc. In particular, in FIG. 1B, it will be understood that the portion of pallet 100 forming a thickened frame of rectangular outline is not implemented as a solid block, but rather as a structure of outer walls and interposed ribs, as is well-known in the field. The upward facing structure may also include various features for stabilizing or gripping a load placed on top of the pallet, and/or drainage openings for facilitating rinsing and drying of the pallet, all as is known in the art.

[0032] In a particularly preferred set of implementations, the legs of the pallet are hollow legs configured to allow nesting of part of the legs of another similar pallet within the hollow legs when similar pallets are stacked. The legs are shown here schematically as rectangular tapered hollow legs. Here again, practical implementation of the legs will typically include internal reinforcing ribs which define a maximum extent of nesting, thereby preventing locking-together of the pallets during nesting, as well as various other variations in the leg shape to provide enhanced strength, reduced interruption to the deck surface, and other structure, functional or esthetic features, all as are known in the art.

[0033] Due to the enhanced structural strength of the pallet resulting from the inter-engaged elongated reinforcing elements, it may be possible to support loads that are conventionally supported by a 9-leg pallet using fewer legs. The minimum number of legs is four legs 104a, which are typically located at or near the corners of the pallet. Where additional legs are used, mid-edge legs 104b are typically added, integrated into the rectangular frame structure around the periphery of the pallet.

[0034] Where a conventional 9-leg format is desired, an additional central leg 104c is provided. In this case, in order to avoid reinforcing the central deck-forming structure 118 in a manner that might compromise the weight-reduction of plastic employed in the pallet, central leg 104c is preferably formed with features for directly engaging the elongated reinforcing elements in at least one and preferably both directions. Thus, in the example shown here, central leg 104c is formed with its own small support frame 120 which includes segments of channels 106 and 108 for receiving the two first elongated reinforcing elements 110 and the two second elongated reinforcing elements 112 adjacent to that leg. This rigidly fixes the position of central leg 104c relative to the outer frame, resulting in a strong and rigid overall structure without a major increase to the weight of plastic employed in the pallet. Here too, the channels can be non-continuous, and may be formed by moving cores or by opposing shut-offs, all as discussed above.

[0035] The form of inter-engagement of the reinforcing elements requires a specific sequence of assembly, corresponding to a distinctive method of assembly of a pallet according to the teachings of an embodiment of the present embodiment. As best appreciated with reference to FIG. 2, the method starts with providing unitary plastic body 102 according to any of the defining features described above. Specifically, unitary plastic body 102 has a rectangular perimeter with a first dimension D1 and a second dimension D2, and has at least four legs 104a for supporting the unitary plastic body above the underlying surface. The unitary plastic body 102 also includes a first plurality of channels 106 extending parallel to the first dimension D1 and open to at least one edge of the unitary plastic body 102, and a second plurality of channels 108 extending parallel to the second dimension D2 and open to at least one edge of the unitary plastic body 102.

[0036] The first set of elongated reinforcing elements 110 are then inserted along the first plurality of channels 106 so as to extend along a majority of first dimension D1, and so that apertures 114 are aligned with the second plurality of channels 108. The second set of elongated reinforcing elements 112 are then inserted along the second plurality of channels 108 so as to pass through apertures 114 in the first set of elongated reinforcing elements 110 and to extend along a majority of the second dimension D2. This results in the reinforced pallet structure with bidirectional inter-engaged reinforcing elements as described above.

[0037] In the case illustrated here, four reinforcing elements are used in each direction. This is highly advantageous for the case of a 9-leg pallet, where each reinforcing element passes adjacent to a corresponding row of legs, with reinforcing elements on both sides of the middle row of legs. The proximity of the legs to the reinforcing elements ensures effective transfer of load from the reinforcing structure to the legs for supporting the load. The use of 4 reinforcing elements in each direction also generates 16 cross-over locations 116, contributing to a highly inter-engaged rigid grid structure which provides the strength and rigidity of the pallet. Nevertheless, alternative configurations may in some cases be preferred, employing more or fewer reinforcing elements in one or both directions. In each case, the position and structure of the corresponding channels are adapted accordingly.

[0038] In the example illustrated thus far, first elongated reinforcing elements 110 have a rectangular cross-section and second elongated reinforcing elements 112 have a circular cross-section. The rectangular cross-section is a particularly simple structure known to provide effective reinforcement and, since the continuity of the upper and lower surfaces is uncompromised by the side-to-side apertures 114, most of the load-bearing strength is preserved. The use of circular rods for the second dimension has advantages in that the corresponding circular apertures 114 in the rectangular elements 110 do not result in localized concentrations of stress. However, a wide range of other forms can be used both for elements 110 and elements 112. Some of these options are exemplified in FIGS. 3-5.

[0039] Referring to FIG. 3, this illustrates a variant implementation of a pallet, generally designated 200, constructed and operative according to a further embodiment of the present invention, in which both the first and second sets of elongated reinforcing elements 210 and 212 are formed with a rectangular cross-section. In all other respects, the structure and function of pallet 200, and the corresponding method of assembly, are analogous to those of pallet 100 described above, with equivalent elements labeled similarly.

[0040] FIG. 4 illustrates a further variant implementation of a pallet, generally designated 300, constructed and operative according to a further embodiment of the present invention, in which the first set of elongated reinforcing elements 310 are implemented with an I-beam cross-section. As in FIG. 2, elongated reinforcing elements 312 are again shown here as having a circular cross-section. In all other respects, the structure and function of pallet 300, and the corresponding method of assembly, are analogous to those of pallet 100 described above, with equivalent elements labeled similarly.

[0041] Finally, in FIG. 5, there is shown a further variant implementation of a pallet, generally designated 400, constructed and operative according to a further embodiment of the present invention, in which the first set of elongated reinforcing elements 410 are implemented as rectangular cross-section elements while it is the second set of elongated reinforcing elements 412 which are here implemented with I-beam cross-sections. In all other respects, the structure and function of pallet 400, and the corresponding method of assembly, are analogous to those of pallet 100 described above, with equivalent elements labeled similarly.

[0042] In each case of the above embodiments, the corresponding channels 106 and 108 are formed with complementary shapes to accommodate the reinforcing elements. Those shapes may be close-fitting shapes or any other suitable shape for accommodating the corresponding elements.

[0043] In the above description, all of the examples have shown D1 as being the longer dimension or length of the pallet while D2 has denoted the shorter dimension or width. The invention can equally be implemented where D1 is the width and D2 is the length, such that the apertures are formed in the elongated reinforcing element which extend across the width, which are inserted first during assembly, and the longer reinforcing elements along the length pass through those apertures. Similarly, the invention can be implemented for square pallets.

[0044] It will be appreciated that the above descriptions are intended only to serve as examples, and that many other embodiments are possible within the scope of the present invention as defined in the appended claims.