Horizontally supported planar surfaces – Industrial platform – Having plastic load-contacting surface
Reexamination Certificate
1999-09-07
2001-04-17
Chen, Jose V. (Department: 3624)
Horizontally supported planar surfaces
Industrial platform
Having plastic load-contacting surface
Reexamination Certificate
active
06216609
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
FIELD OF THE INVENTION
The field of the invention is pallets, and more particularly, injection molded plastic pallets having structural hollow channels.
BACKGROUND OF THE INVENTION
Plastic pallets are in common use in many industries. They are used as load platforms for easily transporting loads using material handling equipment, such as fork lift trucks and the like. A typical pallet has a deck with an upper surface for supporting a load and a lower surface which is engaged by the material handling equipment when in transit.
The load on a typical pallet causes the pallet deck to deflect concave upward in the areas between the feet and to compress the feet of the pallet, while lifting or transporting the pallet by engaging the material handling equipment causes the pallet deck to deflect concave downward. Constant movement of the pallet subjects a pallet deck to a continuous cycle of upward and downward deflections, weakening the pallet structure and eventually causing the pallet to fail.
One method which prolongs the life of a plastic pallet is to add material to the structural components of the pallet increasing the pallet stiffness and capability to withstand many deflection cycles. This method, however, increases the weight and cost of the pallet.
Plastic pallets have in general been made by either rotational molding, single of twin sheet vacuum thermoforming, or injection molding. Rotational molding and vacuum thermoforming can be used to create voids within the pallets, but also results in thin walled sections of relatively low strength. Injection molding is capable of forming thicker walled sections and solid reinforcing ribs resulting in a pallet of solid material with less strength than what the same volume of material is capable of. Thus, a need exists for a method of increasing the strength of material handling pallets, without increasing the weight or cost.
SUMMARY OF THE INVENTION
The present invention provides an injection molded structural channel pallet having improved structural integrity without adding material to increase the pallet weight. The pallet has a deck having a top and a bottom, and a number of feet are formed extending downwardly from the deck. Ribs define an open grid pattern in the deck, and hollow channels are formed in the deck, which increases the strength of the pallet, without disproportionately increasing the volume of weight of material used. The hollow channels are formed at strategic locations on the top and the bottom of the deck.
A general objective of the present invention is to provide an injection molded plastic pallet having increased strength, while reducing its weight and volume of material used in comparison to a solid pallet of the same capacity or exterior dimensions. This objective is accomplished by forming hollow channels at strategic locations in the pallet deck. In one embodiment the hollow channels strategically define substantially identical patterns in pallet quadrants defined by a pallet longitudinal and lateral axis. Each channel pattern has primary channels. One primary channel extends along a diagonal across the quadrant. Secondary channels may branch off of at least one of the primary channels.
Another objective of the present invention is to reduce pallet deflection when the pallet is supporting a load or being lifted by material handling equipment. This objective is accomplished by providing hollow channels in a pattern which cross over between the pallet deck top and bottom.
Yet another objective of the present invention is to provide a pallet with strengthened feet to support the pallet deck, and increase the pallet load capacity. This objective is accomplished by forming hollow channels around the feet top and down along the feet sides. In one embodiment, the primary channels in the pattern encircle the tops of the pallet feet, and are formed in the corners of convolutions in the feet sides.
The foregoing and other objects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention.
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Chen José V.
Menasha Corporation
Quarles & Brady LLP
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