Plastic Pallet with Bidirectional Intersecting Reinforcing Elements and Corresponding Manufacturing Methods

The present invention relates to pallets and, in particular, it concerns a plastic pallet with bidirectional intersecting reinforcing elements and corresponding manufacturing methods.

The advantages of injection molded plastic pallets are well-established in the logistics industry, offering a lightweight, durable, and hygienic alternative to traditional wooden pallets. Nestable pallets also offer significant savings in the return shipping costs of empty pallets by reducing the required shipping volume. However, conventional plastic pallets can struggle to meet stringent flammability regulations set by various governmental authorities.

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

According to the teachings of an embodiment of the present invention there is provided, 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 the unitary plastic body above the underlying surface, the unitary plastic body including a first plurality of channels extending parallel to the first dimension and open to at least one edge of the unitary plastic body, and a second plurality of channels extending parallel to the second dimension and open to at least one edge of the unitary plastic body; (b) a first set of elongated reinforcing elements deployed within the first plurality of channels and extending along a majority of the first dimension, the first set of elongated reinforcing elements having apertures aligned with the second plurality of channels; and (c) a second set of elongated reinforcing elements deployed within the second plurality of channels and passing through the apertures in the first set of elongated reinforcing elements, the second set of elongated reinforcing elements extending along a majority of the second dimension.

According to a further feature of an embodiment of the present invention, the unitary plastic body includes a deck for supporting the load, the deck spanning the first and second dimensions.

According to a further feature of an embodiment of the present invention, the legs 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.

According to a further feature of an embodiment of the present invention, the first set of elongated reinforcing elements have a rectangular cross-section.

According to a further feature of an embodiment of the present invention, the first set of elongated reinforcing elements have an I-beam cross-section.

According to a further feature of an embodiment of the present invention, the second set of elongated reinforcing elements have a circular cross-section.

There is also provided according to the teachings of an embodiment of the present invention, 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 the unitary plastic body above the underlying surface, the unitary plastic body including a first plurality of channels extending parallel to the first dimension and open to at least one edge of the unitary plastic body, and a second plurality of channels extending parallel to the second dimension and open to at least one edge of the unitary plastic body; (b) inserting a first set of elongated reinforcing elements along the first plurality of channels so as to extend along a majority of the first dimension, the first set of elongated reinforcing elements having apertures aligned with the second plurality of channels; and (c) inserting a second set of elongated reinforcing elements along the second plurality of channels so as to pass through the apertures in the first set of elongated reinforcing elements and to extend along a majority of the second dimension.

According to a further feature of an embodiment of the present invention, the unitary plastic body includes a deck for supporting the load, the deck spanning the first and second dimensions.

According to a further feature of an embodiment of the present invention, the legs 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.

According to a further feature of an embodiment of the present invention, the first set of elongated reinforcing elements have a rectangular cross-section.

According to a further feature of an embodiment of the present invention, the first set of elongated reinforcing elements have an I-beam cross-section.

According to a further feature of an embodiment of the present invention, the second set of elongated reinforcing elements have a circular cross-section.

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

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.

Referring now to the drawings,illustrate a pallet, generally designated, 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 bodyhaving a rectangular perimeter with a first dimension Dand a second dimension D, and having at least four legsfor supporting the unitary plastic body above the underlying surface. The unitary plastic bodyalso includes a first plurality of channels(best seen in) extending parallel to the first dimension Dand open to at least one edge of the unitary plastic body, and a second plurality of channels(best seen in) extending parallel to the second dimension Dand open to at least one edge of the unitary plastic body. The pallet also includes a first set of elongated reinforcing elementsdeployed within channelsand extending along a majority of the first dimension Dand a second set of elongated reinforcing elementsdeployed within channelsand extending along a majority of the second dimension D. Elongated reinforcing elementshave apertures(best seen in) positioned so as to align with channels. Aperturesare sized and shaped to receive elongated reinforcing elementspassing through the apertures, resulting in an inter-engagement of elementsandat multiple cross-over locationsas they extend through the pallet, best seen in.

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. Thus, channelsand/ordo not need to be continuous along the length of the reinforcing elements. Thus, in the example illustrated here in, various portions of the length of the reinforcing elementsandare 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 locationswhere 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.

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.

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 bodyfurther includes a central deck-forming structurewhich, together with the top surface of the outer frame, forms a deck for supporting the load which spans the first and second dimensions Dand D. The central deck-forming structureis 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 elementsand/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 structureis formed with a set of ridges running perpendicular to the first set of reinforcing elements, which help to provide enhanced directional rigidity of this surface between adjacent reinforcing elements. Even with these ridges, the central deck-forming structureremains 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.

The representations of palletare shown only schematically, without any attempt to show details of the plastic molding structures, such as arrangements of spaced ribs etc. In particular, in, it will be understood that the portion of palletforming 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.

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.

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, which are typically located at or near the corners of the pallet. Where additional legs are used, mid-edge legsare typically added, integrated into the rectangular frame structure around the periphery of the pallet.

Where a conventional 9-leg format is desired, an additional central legis provided. In this case, in order to avoid reinforcing the central deck-forming structurein a manner that might compromise the weight-reduction of plastic employed in the pallet, central legis 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 legis formed with its own small support framewhich includes segments of channelsandfor receiving the two first elongated reinforcing elementsand the two second elongated reinforcing elementsadjacent to that leg. This rigidly fixes the position of central legrelative 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.

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, the method starts with providing unitary plastic bodyaccording to any of the defining features described above. Specifically, unitary plastic bodyhas a rectangular perimeter with a first dimension Dand a second dimension D, and has at least four legsfor supporting the unitary plastic body above the underlying surface. The unitary plastic bodyalso includes a first plurality of channelsextending parallel to the first dimension Dand open to at least one edge of the unitary plastic body, and a second plurality of channelsextending parallel to the second dimension Dand open to at least one edge of the unitary plastic body.

The first set of elongated reinforcing elementsare then inserted along the first plurality of channelsso as to extend along a majority of first dimension D, and so that aperturesare aligned with the second plurality of channels. The second set of elongated reinforcing elementsare then inserted along the second plurality of channelsso as to pass through aperturesin the first set of elongated reinforcing elementsand to extend along a majority of the second dimension D. This results in the reinforced pallet structure with bidirectional inter-engaged reinforcing elements as described above.

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 generatescross-over locations, 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.

In the example illustrated thus far, first elongated reinforcing elementshave a rectangular cross-section and second elongated reinforcing elementshave 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, most of the load-bearing strength is preserved. The use of circular rods for the second dimension has advantages in that the corresponding circular aperturesin the rectangular elementsdo not result in localized concentrations of stress. However, a wide range of other forms can be used both for elementsand elements. Some of these options are exemplified in.

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

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

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

In each case of the above embodiments, the corresponding channelsandare 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.

In the above description, all of the examples have shown Das being the longer dimension or “length” of the pallet while Dhas denoted the shorter dimension or “width”. The invention can equally be implemented where Dis the width and Dis 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.

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.