BACKGROUND OF THE INVENTION
The present invention relates to a pallet assembly and more particularly to a plastic pallet with reinforcement members.
Pallets are often used to store and transport goods. Pallets maintain the goods at a distance above the floor such that they can readily be lifted and moved by a forklift. Plastic pallets are lighter and more durable than wooden pallets. Elongated metal or composite reinforcement members have been used in some plastic pallets in order to increase the stiffness and load-bearing capacity of the pallet.
Some pallets comprise upper and lower decks separated by a plurality of columns that maintain the space between the upper and lower decks. The pallets may have reinforcement bars sandwiched between two layers in the upper deck or the lower deck. Traditionally, the reinforcement bars were straight bars inserted into the upper deck. One pallet previously developed by the assignee of the present invention includes reinforcement members with a frame or peripheral rail extending continuously and completely about the outer periphery of the deck and a pair of perpendicular cross beams connected to the peripheral rail. The cross beams are centered on the columns for support and the peripheral rail is also either centered on the columns or positioned outwardly of center of the columns.
It is desirable to minimize the number of components of the pallet and minimize the weight of the pallet while retaining the rigidity of the pallet. Additionally, some plastic pallets are evaluated for their performance under Underwriters Laboratories, Inc. (UL) Standard 2335, which, in part, evaluates the heat release performance of plastic pallets while stored on racks having inwardly extending ledges upon which the pallets are supported. Ways have been sought to manufacture the pallets of fire-retardant materials.
SUMMARY OF THE INVENTION
The present invention provides a reinforced pallet assembly with fewer components, increased strength, reduced weight and improved performance under UL standard 2335.
The pallet assembly of the present invention includes an upper deck and a lower deck spaced by a plurality of columns. In a first feature described below, the weight of the pallet is reduced without significant reduction in strength by providing only a single cross beam in each of the upper and lower reinforcement members and orienting them perpendicular to one another.
In another feature according to the present invention, the size of the reinforcement members are minimized for weight reduction and for improved performance under UL standard 2335. The reinforcement members each include a frame or peripheral rail. The peripheral rail of the upper reinforcement member is minimized such that it rests on only an inwardly open recess on an inner corner of each of the corner columns. This reduces the size and weight of the upper reinforcement member, while still providing support to the upper deck. Additionally, the peripheral rail of lower deck is reduced in length such that neither ledge directly supports it while the pallet is stored on a rack. Similarly, the length of the peripheral rail of the upper deck is also less than the distance between the ledges. The reinforcement members are spaced from the pallet outer edges of the pallet by a distance greater than the width of the ledges. In one embodiment, the outer dimensions of the reinforcement members are less than the distance between an inner edge of one ledge to the inner edge of the opposite ledge. As a result, in the Commodity Classification test portion of UL standard 2335, the pallets will eventually collapse without interference from the reinforcement members and at least partially smother the heat source.
BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying scale drawings wherein:
FIG. 1 is a perspective view of the pallet assembly according to the present invention.
FIG. 2 is a perspective view of the lower deck and lower reinforcement member of the pallet of FIG. 1.
FIG. 3 is a plan view of the lower deck and lower reinforcement member of FIG. 2.
FIG. 3A is an enlarged view of a portion of the lower deck and lower reinforcement member of FIG. 3.
FIG. 3B is a section view of the lower deck and reinforcement member taken along line 3B-3B of FIG. 3A.
FIG. 4 is a perspective view of the lower reinforcement member and columns of FIG. 1.
FIG. 5 is a perspective view of the columns, lower reinforcement member and lower deck of FIG. 1.
FIG. 6 is a perspective view of the upper reinforcement member, columns, lower reinforcement member and lower deck of FIG. 1.
FIG. 7 is a plan view of the sub-assembly of FIG. 6.
FIG. 8 is a side view of the pallet assembly of FIG. 1.
FIG. 9 is a top view of the pallet assembly of FIG. 1.
FIG. 10 is a bottom view of the pallet assembly of FIG. 1.
FIG. 11 is a side view of the pallet assembly of FIG. 1 positioned on a rack.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
A pallet assembly 10 according to the present invention is illustrated in FIG. 1. The pallet assembly 10 generally includes a molded plastic upper deck 12 and a molded plastic lower deck 14 spaced apart by a plurality of molded plastic columns 16. A lower reinforcement member 20 is received within a channel 22 formed in the upper surface of the lower deck 14. A tapered molded rail 35 extends around the entire periphery of the lower deck 14 to ease fork entry into openings defined between the columns 16.
FIG. 2 illustrates the lower deck 14 and lower reinforcement member 20. As can be seen in FIG. 2, the lower reinforcement member 20 comprises two laterally extending rail sections 26a and 26b at opposite ends of the lower deck 14 and three longitudinally extending rail sections 24a, 24b and 24c connecting the laterally extending rail sections 26a and 26b. The two laterally extending rail sections 26a, 26b together with two of the longitudinally extending rail sections 24a and 24c are connected at rounded corners 28 to form a frame or peripheral rail, generally about the periphery of the bottom deck 14. The center longitudinally extending rail section 24b connects the laterally extending rail sections 26a and 26b. The central longitudinally extending rail section 24b generally bisects the opening defined by the peripheral rail of the lower reinforcement member 20 to create a first uninterrupted space 25a defined among the rail sections 24a, 24b, 26a, 26b and a second uninterrupted space 25b between rail sections 24b, 24c, 26a, 26b. In the embodiment shown, there is no cross bar perpendicular to the center longitudinally extending rail section 24b. All of the lower reinforcement member 20 is received within the channel 22 formed in the lower deck 14. The channels 22 pass through column mounts 30 formed in the lower deck 14. The column mounts 30 are molded recesses for receiving columns 16 (shown in FIG. 1). As can be seen in FIG. 2, the channels 22 and the lower reinforcement member 20 pass through each of the column mounts 30. The reinforcement member 20 may be formed of any material having the desired properties, including metal (such as steel) or composite material, and may have a tubular or I-beam cross-section or any known shape for reinforcement members.
The lower deck 14 further includes a plurality of molded pockets 32 alternating with molded protrusions 34 on either side of channels 22. These provide reinforcement to the lower deck 14 and improve cleanliness because they do not create small cavities that entrap dirt as do typical, closely-spaced ribs extending in the same direction from a planar member that form many cavities opening in the same direction. Each molded pocket 32 and molded protrusion 34 forms a corresponding molded protrusion 34 and molded pocket 32, respectively, on the underside of the lower deck 14. A tapered molded rail 35 extends around the entire periphery of the lower deck 14 outside of the molded protrusions 34 and pockets 32. The tapered molded rail 35 provides ease of fork entry and minimizes pallet damage by guiding the fork tines into the openings during fork entry.
As can be seen in FIG. 3, the laterally extending rail sections 26a and 26b are spaced from the outer edges of the lower deck 14 by a distance x. The longitudinally extending rail sections 24a and 24c are spaced from the outer edges of the lower deck 14 by a distance y. As will be explained below, the distances x and y may vary based upon the particular pallet size, or pallet standard, or particular application. In the embodiment shown, for a 40″ by 48″ pallet, x is preferably greater than two inches and more preferably approximately three inches. In the particular embodiment shown, x is three inches. The y dimension could differ from the x dimension, but in the preferred embodiment is similarly preferably greater than two inches and more preferably approximately two and a half inches. In the particular embodiment shown, y is two and a half inches.
FIG. 3A is an enlarged view of a portion of the lower deck 14 and lower reinforcement member 20 in which it can be seen that the rail section 26a of the reinforcement member 20 is positioned in the channel 22 between flex ribs 37 extending from either side of channel 22 toward the rail section 26a. The flex ribs 37 can also be seen in FIG. 3B. The flex ribs 37 serve two purposes. First, during manufacture the extent to which the ribs extend inwardly can be adjusted by modifying the mold more easily than modifying the mold in order to move an entire wall of the channel 22. This adjustment feature can be used to accommodate manufacturing tolerances between the reinforcement member 20 and the lower deck 14. Also, when in use, the flex ribs 37 provide some flexibility such that the different rates of thermal shrinkage and expansion between the reinforcement members can be accommodated by flexure of the flex ribs 37. Additionally, the flex ribs 37 permit the plastic deck 14 to flex in relation to the rigid reinforcement member 20 during impact and/or loading. In general, the reinforcement member 20 is free floating within the channel 22 in the x and y directions and sandwiched in the z direction.
FIG. 4 illustrates the lower reinforcement member 20 and columns 16. Each of the columns 16 includes cross-ribs 36 extending vertically through the columns. Formed in the cross-ribs 36 in each column is a lower channel 40 passing through the lower end of the column 16 and into which the lower reinforcement member 20 is received such that lower edges of the cross-ribs 36 abut the lower reinforcement member 20. Each of the columns 16, other than the corner columns 16, also includes an upper channel 42 through an upper end of the cross-ribs 36 of the column 16. At the upper end of each of the corner columns 16 is an inwardly open corner recess 44 for receiving a reinforcement member.
FIG. 5 illustrates the lower reinforcement member 20 and columns 16 with the addition of the lower deck 14. As can be seen in FIG. 5, the columns 16 are secured to the lower deck 14 over the lower reinforcement member 20 and the column mounts 30 via snap-fit connections and/or heat staking, adhesive, hot-plate welding, or other known methods.
FIG. 6 illustrates the sub-assembly of FIG. 5 with the addition of the upper reinforcement member 50. The upper reinforcement member 50 comprises longitudinally extending rail sections 54a and 54b and laterally extending rail sections 56a, 56b and 56c. The longitudinally extending rail sections 54a and 54b are joined with the outer laterally extending rail sections 56a and 56c at rounded corners 48 to form a peripheral rail with a single cross-bar 56b extending from longitudinally extending rail 54a to longitudinally extending rail section 54b. The center laterally extending rail section 56b generally bisects the opening defined by the peripheral rail sections and defines an uninterrupted space 58a among rail sections 56b, 56c, 54a, 54b and an uninterrupted space 58b among rail sections 56b, 56a, 54a, 54b. Each of the rail sections is received within a channel 42 in the cross ribs 36 in the upper end of the columns 16 such that the upper edges of the cross-ribs 36 abut the upper reinforcement member 50. Each of the rounded corners 48 is received within the inwardly open corner recess 44 formed on each of the inner corners of each of the corner columns 16.
FIG. 7 is a top view of the sub-assembly of FIG. 6. As can be seen in FIG. 7, the upper reinforcement member 50 is positioned inwardly of the lower reinforcement member 20. In particular, the laterally extending rail sections 56a and 56c are positioned a distance y′ from the outer edge of the decks and are disposed completely inwardly of the laterally extending rail sections 26a, 26b of the lower member 20. The distance y′ is preferably greater than two inches, more preferably greater than three inches and most preferable five and a half inches. The longitudinally extending rail sections 54a, 54b of the upper reinforcement member 50 are positioned at a distance x′ from the outer edge of the decks and at least partially inwardly of the longitudinally extending rail sections 24a and 24c of the lower member 20. The distance x′ is preferably greater than two inches and more preferably greater than three inches. In the embodiment shown, x′ is three and a half inches.
FIG. 8 is a side view of the completely assembled pallet assembly 10 of FIG. 1. As can be seen in FIG. 8, the upper deck 12 includes a plurality of cross-rib members 60 extending downwardly to provide increased support. FIG. 9 is a top view of the pallet assembly 10 according to the present invention.
FIG. 10 is a bottom view of the pallet assembly 10, showing the cross-rib members 60 on the underside of the upper deck 12 which also define a channel 62 into which the reinforcement member 50 is received. FIG. 10 also shows the molded pockets 32 and protrusions 34 formed on the underside of the lower deck 14 and the molded rail 35 around the periphery of the lower deck 14. Ribs 68 extend downwardly inside the molded rail 35. The channel 62 of the upper deck 12 also includes flex ribs 69 similar to those described above with respect to the lower deck 14.
FIG. 11 illustrates the pallet assembly 10 mounted in a rack 70 having ledges 72 extending perpendicularly from vertical supports 74. For one known rack, the standard width for the ledges 72 is two inches. Thus, by ensuring that the distance, x and x′, from the outer edges of the pallet assembly 10 to the reinforcement members exceed the width of the ledges 72, in the event that a heat source or other source causes the pallet assembly 10 to collapse. In other words, the distance z1 between an inner edge of one ledge 72 to an inner edge of the opposite ledge 72 is preferably greater than the outer dimension z2 of the reinforcement members 20 and 50. The collapsing pallet assembly may in some circumstances assist in at least partially smothering the heat source that may be located below.
The upper and lower decks 12, 14 of the pallet assembly 10 of the present invention are each preferably formed in one piece of polypropylene via an injection molding process, but of course can be formed of any type of plastic applicable for the desired use. The columns 16 are each preferably formed in one piece of polyethylene via an injection molding process, but of course can be formed of any type of plastic applicable for the desired use. The materials may be chosen and distributed in accordance with the teachings of co-pending U.S. patent application Ser. No. 10/040,098, entitled “Pallet Assembly,” filed Oct. 19, 2001, commonly assigned and hereby incorporated by reference in its entirety. While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. There are many different configurations for pallet assemblies and many variations in design, many of which would benefit from the present invention.
Patent Application
20100083881
