Patent Application
20110132237
The present invention relates to the field of pallets, and more particularly, to a wooden pallet having an improved resilience to impacts from material handling equipment, and to related methods for making the same.
Conventional wood pallets include a base layer and a cargo layer separated therefrom by support blocks. Traditionally, the base and cargo layers respectively have end deck boards assembled on connector boards that run the full length or width of the pallet. The end deck boards are nailed through the connector boards into the support blocks to build the primary structure of the pallet. The end deck boards are also known as lead boards, and the connector boards are also known as stringer boards.
To move the wooden pallets with cargo thereon, forklift tines are inserted into the gaps between the base and cargo layers. If the forklift is not stopped in time, the forklift crashes into one of the end deck boards of the pallet. Impacts such as this weaken the pallet and greatly shorten the lifespan of the pallet, thereby causing the pallet to be repaired more frequently and/or removed from service before its anticipated life cycle has been reached.
In an effort to improve pallet durability, nail plates have been used to strengthen wood pallet joints. U.S. Pat. No. 7,056,074 to Bas discloses nail plates between an upper surface of the support blocks and boards in the cargo layer, and between a lower surface of the support blocks and boards in the base layer. Each nail plate includes projections extending from upper and lower surfaces thereof, and a center opening for receiving a connecting device. A respective connecting device is used for each support block to couple the corresponding boards in the cargo and base layers to each support block, with the corresponding nail plates penetrating into opposing wood surfaces.
Similarly, U.S. Pat. No. 6,584,915 to Rogers discloses nail plates to strengthen wood pallet joints. The nail plates are between the end deck boards and the support blocks, wherein the projections from the nail plates are embedded into the support blocks. In particular, the projections for each nail plate are grouped into two bands to leave a central or median region that is void of any projections. Nails are driven through the central or median region of the nail plates.
Yet a further use of nail plates is disclosed in U.S. Pat. No. 7,516,705 to Hedstrom. The '705 patent is assigned to the current assignee of the present invention, and is hereby incorporated by reference in its entirety. The nail plates are between the connector boards and the support blocks, wherein the projections from the nail plates are embedded into the connector boards.
Even in view of the above noted nail plates, there is still a need to further improve the resiliency of a wooden pallet to impacts from material handling equipment.
In view of the foregoing background, it is therefore an object of the present invention to provide a wooden pallet that is resilient to impacts from material handling equipment.
This and other objects, advantages and features in accordance with the present invention are provided by a wooden pallet comprising a base layer, and a cargo layer. The cargo layer may comprise a pair of spaced apart connector boards, and a pair of spaced apart end deck boards orthogonal to the pair of connector boards. Respective ends of the pair of end deck boards may overlap respective ends of the pair of connector boards. Nail plates may be coupled between the respective ends of the pair of connector boards and the respective ends of the pair of end deck boards. Each nail plate may have a first surface that includes projections extending outwards therefrom and embedded into the end of one of the end deck boards, and a second surface opposite the first surface devoid of any projections and contacting the end of one of the connector boards. Spaced apart support blocks may be between the base layer and the pair of connector boards in the cargo layer, and form a gap therebetween for receiving a lifting member.
The cargo layer may further comprise a plurality of spaced apart intermediate deck boards between the pair of end deck boards and coupled to the pair of connector boards, with a gap area being defined between an inside edge of each end deck board and an adjacent one of the intermediate deck boards. Each nail plate may comprise a backstop extending within the gap area and contacting the inside edge of one of the end deck boards to absorb an impact to an outside edge thereof.
The backstop may be triangular shaped with an open interior. An upper corner of the inside edge of each end deck board may be notched, and wherein an upper tip of the backstop may be angled into the notch. The upper tip may be substantially coplaner with an upper surface of the end deck board.
Each nail plate may be stamped from a single metal sheet. The plurality of projections may comprise rounded tips. The plurality of projections may be arranged in rows and columns. The rows and columns may be in a zig-zag pattern.
The pallet may further comprise a plurality of fasteners coupling the pair of end deck boards and the pair of connector boards to the plurality of support blocks.
The base layer may comprise a pair of spaced apart end deck boards and a pair of spaced apart connector boards orthogonal to the pair of end deck boards. The pair of end deck boards and the pair of connector boards may be non-overlapping. The pallet may further comprise a plurality of nail plates coupled between respective ends of the pair of end deck boards and the plurality of support blocks. Each nail plate may have a first surface comprising a plurality of projections extending outwards therefrom and embedded into one of the end deck boards, and a second surface opposite the first surface and devoid of any projections, and contacting a support block.
The wooden pallet may also comprise a plurality of nail plates coupled between respective ends of the pair of connector boards and the plurality of support blocks. Each nail plate may have a first surface comprising a plurality of projections extending therefrom and embedded into one of the connector boards, and a second surface opposite the first surface and devoid of any projections, and contacting a support block.
Another aspect of the wooden pallet is directed to the nail plates, wherein each nail plate may have a length corresponding to a length of an end deck board. This simplifies the manufacturing process.
Yet another aspect is directed to a method for making a wooden pallet, as described above.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and prime and double prime notations are used to indicate similar elements in alternative embodiments.
Referring initially to
The cargo layer 30 comprises a pair of spaced apart top connector boards 32, and a pair of spaced apart top end deck boards 34 orthogonal to the top connector boards so that the cargo layer has a rectangular shape. The top connector boards 32 are also known as stringer boards, and run the full length of the pallet 10. The ends of the top connector boards 32 are between the support blocks 40 and the top end deck boards 34. In other words, top connector boards 32 and the top end deck boards 34 are non-coplanar. The cargo layer 30 further comprises spaced apart intermediate top deck boards 36 coupled to the top connector boards 32. The intermediate top deck boards 36 are substantially parallel to the top end deck boards 34.
The base layer 20 comprises a pair of spaced apart bottom end deck boards 24, and a pair of spaced apart bottom connector boards 22 orthogonal to the bottom end deck boards so that the base layer also has a rectangular shape. The bottom connector boards 22 are coplanar with the bottom end deck boards 24. In other words, the bottom end deck boards 24 contact the support blocks 40, and the bottom connector boards 22 contact the support blocks 40.
In particular, nail plates 50, 52 are used in the base and cargo layers 20, 30 to increase the resiliency of the pallet 10, as highlighted by the fragmentary sections 60 in
In the cargo layer 30, the nail plates 50 are between the top end deck boards 34 and the top connector boards 32. In the base layer 20, the nail plates 50 are between the bottom end deck boards 24 and the support blocks 40, and the nail plates 52 are between the bottom connector boards 22 and the support blocks 40. As readily appreciated by those skilled in the art, the nail plates 50 in the cargo layer 30 may be used without the nail plates 50, 52 in the base layer 20, and vice-versa.
As best illustrated in
In the illustrated embodiment, the nail plate 50 is about 100 millimeters by 100 millimeters (i.e., about 4×4 inches). The nail plate 52 is smaller in size since it covers a limited area. In the illustrated embodiment, the nail plate 52 is about 25 millimeters by 100 millimeters (i.e., 1×4 inches). The size of the nail plates 50, 52 can vary depending on the intended application, as readily appreciated by those skilled in the art.
The metal sheet used for forming the nail plates 50, 52 has a thickness within a range of about 1 to 5 millimeters, for example. The thickness of the nail plates 50, 52 does not prevent nails 60 or other fastening devices from penetrating therethrough. A length of the projections 56 is within a range of about 5 to 15 millimeters, for example.
The tips of the projections 56 from the nail plates 50, 52 are curved/rounded. This advantageously reduces the risk of injury should the pallet 10 become damaged to the point where the projections from the nail plates are exposed as a result of missing wood. The projections 56 in the illustrated nail plate 50 are in a zig-zag pattern. As readily appreciated by those skilled in the art, the projections are not limited to a zig-zag pattern. For example, the projections may be lined up in rows, arcs and/or columns that may be evenly spaced as well non-evenly spaced.
Referring now to
As illustrated in
In a different embodiment, the nail plate 50′ is one piece so that it substantially extends the length of the top end deck boards 34, as illustrated in
To further increase the resiliency of the pallet 10, higher density wood may be chosen to form the top and bottom end deck boards 34 and 24, as well as the bottom connector boards 22. By combining the use of higher density wood with the nail plates 50 and 52, the pallets 10 are further able to withstand impacts over a longer period of time. This also results in an improved shear resistance and bending performance for loaded boards/pallets.
In other words, the strength and durability of the pallet 10 increases as the wood density increases. One category of wood density is “dense softwood” that generally includes wood having a density within a range of about 500 to 650 kg/m3. This type of wood includes Southern Yellow Pine, for example. Another category of wood density is “dense hardwood” that generally includes wood having a density within a range of about 650 to 800 kg/m3. This type of wood includes oak, beech, ash, maple, cherry, teak, gum and mahogany, for example.
As readily appreciated by those skilled in the art, both wood density and elimination of split initiation (because of the nail plates 50, 52) are critical to reducing damage in top end deck boards 34 and the bottom end deck boards 24. This results in decreased missing wood for increased customer satisfaction.
Another embodiment of the nail plate 50″ will now be discussed in reference to
When an impact force is applied to the outside edge of the top end deck board 34″, the force is transmitted to the backstop 70″ of the nail plate 50″ so that the energy of the impact is dissipated over the length of the top end deck board 34. The nail plate 50″ with the backstop 70″ may extend the full length of a top end deck board 34″ (as in
The illustrated backstop 70′ is triangular shaped with an open interior. However, the backstop 70′ may have over shapes as readily appreciated by those skilled in the art. Each nail plate 50″ and backstop 70″ may be stamped from a single metal sheet.
In addition, an upper corner 35″ of the inside edge of each end deck board 34′ may be notched, and an upper tip 71′ of the backstop 70″ may be angled into the notch to provide an additional area to absorb an impact on the outside edge of the same top end deck board 34″. The upper tip 71″ is substantially coplaner with an upper surface of the end deck board 34″. The nail plate 50″ and backstop 70″ may be stamped from a single metal sheet.
In the illustrated nail plate 50″, the projections 56″ project both upwards and downwards. Alternatively, the projections 56″ may project only upwards, or may project only downwards.
Another aspect is directed to a method for making a pallet 10 as described above. Referring now to the flowchart 100 illustrated in
Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included as readily appreciated by those skilled in the art.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/267,664 filed Dec. 8, 2009, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61267664 | Dec 2009 | US |
