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This application claims benefit of U.S. Provisional Patent Application No. 60/654,769, filed Feb. 18, 2005 and is a continuation-in part of U.S. patent application Ser. No. 10/729,615, filed Dec. 5, 2003, which is a divisional of U.S. patent application Ser. No. 09/938,954, filed Aug. 24, 2001, which claimed priority to U.S. Provisional Patent Application Ser. No. 60/227,537, filed Aug. 24, 2000, the entire contents of each of which are specifically incorporated herein by reference.
The present disclosure relates to improvements to the above-cited applications with regard to affixing a deck of a plastic pallet to a frame portion.
A plastic pallet has a deck which is attached to the top frame of the pallet, which is supported on columns running from the base. In a typical design, the periphery of the (e.g.) metal deck is attached to the frame by using metal or plastic fasteners which penetrate through mating holes in the deck and frame.
However, fastening requires a separate operation and certain limitations, and improvements are sought. Among the needs are for lower cost, better strength of attachment, and avoiding areas where dirt can accumulate.
What is needed is an improved deck to frame interface that provides a lower cost, high strength, sealed solution.
The above described need in the art is overcome by the present deck to frame interface, wherein the deck, which may be metal or some other material, is bonded in sealing engagement to the frame of a molded plastic pallet. Such bonding may be by, e.g.: (a) coating the deck and then melting the coating to attach the deck to the frame; (b) providing an adhesive strip within the recess of a frame; (c) injecting the plastic which forms the frame into holes around the periphery of the deck; and/or (d) injecting plastic so a lip of the frame mechanically envelopes the top edge of the deck.
The various exemplary means may be used independently or in combinations. Where utilized, the coating on a metal deck provides the dual purpose of protecting the metal during use and providing the means of attaching the deck to the frame of the pallet.
The foregoing and other objects, features and advantages of the present pallet will become more apparent from the following description of exemplary embodiments and accompanying drawings.
Referring now to the accompanying FIGURES, which are meant to be exemplary and not limiting:
FIG. 1 is a partial cutaway perspective view illustrating a previous deck mounting configuration utilizing metal fasteners;
FIG. 2 is a partial cross sectional view of an exemplary deck mounting configuration utilizing adhesive;
FIG. 3 is a partial cross sectional view of an exemplary deck mounting configuration utilizing injected plastics; and
FIG. 4 is a cross sectional view of an exemplary embedding of a deck in the material of the frame.
As noted above, the present disclosure relates to improvements with regard to mating a deck with a frame on an exemplary thermoplastic pallet. The present disclosure recognizes certain inefficiencies with regard to the process times, the cost, and the design of previous uses of fasteners to affix a pallet deck to a pallet frame, and provides improved mechanisms whereby the deck may be mated with the frame.
Referring now to FIG. 1, a portion of an exemplary pallet 20 utilizing fasteners is illustrated. Pallet 20 has a frame 22 mounted on columns 36 running up from base 34. The illustrated deck 28 is corrugated, and comprises, e.g., aluminum. Deck 28 is attached to a frame 22, e.g., polypropylene, by metal fasteners 38, such as stakes or rivets.
Referring now to FIG. 2, two different exemplary embodiments claimed herein are illustrated. In the first exemplary embodiment, an elastomer adhesive 40 is used to bond the deck 28A to the frame 22 in a sealing arrangement. While the deck 28A is illustrated as having a coating 32, the deck 28A may or may not be coated. In the second exemplary embodiment, the adhesive 40 would not be present, the deck 28A is coated. In one exemplary embodiment, the coating is a polymer coating 32. In other exemplary embodiments, the coating may be polypropylene, polyethylene, thermoplastic olefin, or one of known powder coatings for metals, such as aluminum, among others.
In the first exemplary embodiment, deck 28A is placed in a recess in the frame 22, where an adhesive strip, in this case an L-shape strip of adhesive, such as Neoprene rubber, has been pre-placed by means of a pre-form or dispenser. The adhesive may be pressure sensitive or may be activated by known means after the deck is placed. In this exemplary embodiment, the deck need not have a coating, but it may be desirable. This embodiment also enables use of a deck coating which is not compatible to the material of the molded pallet, when an adhesive is chosen which is mutually adherent to the two materials. Accordingly, a sealed arrangement is achieved whereby the deck is bonded to the frame of a pallet.
As described above, in the second exemplary embodiment the adhesive 40 is not used. A deck 28A (e.g., metal) with a coating 32 is bonded to the frame 22 by localized melting of the coating and/or local portion of the frame, for instance by ultrasonic heating. Thus the deck is securely attached to the frame, taking advantage of the previously well-adhered powder coating. The polymer coating on the deck may then protect it from corrosion and abrasion during use of the pallet, and the deck is effectively bonded to the frame in a sealed configuration.
Referring still to FIG. 2, the coating may also comprise a layer of plastic, which may be provided on the deck 28A at anytime prior to bonding to the frame 22. For example, the deck may be embedding in plastic during the metal stamping used to form corrugations or other contours. The deck 28A may then be attached to the frame by means of plastic welding, for instance ultrasonic, vibratory or hot plate welding. This exemplary construction also can desirably obtain a good seal between the deck and the frame. Also, while FIG. 2 shows a continuous coating 32, which would aid in protecting the metal from corrosion, the layer may also be present only on a portion of the deck in the vicinity of the frame.
Referring now to FIG. 3, a third exemplary embodiment is illustrated, wherein the deck 28B, which may be made of metal or other material, and the frame 22B is formed by injection molding in a mold. Deck 28B is provided with exemplary shaped holes along the edges and is placed within an injection machine mold. The frame 22B is then formed by injection of a plastic into the mold. The injected plastic flows into the holes to form attachment nubs 42. Thus, the deck is bonded to the frame in a sealing engagement.
Referring now to FIG. 4, in another exemplary embodiment, the deck 28C, which may be made of metal or other material, and the frame 22C is formed by injection molding in a mold. The mold is configured such that injected plastic utilized for the frame 22C flows onto the top surface of deck 28C, as lip 23C, to hold the deck in place. Accordingly, the deck is bonded to the frame in a sealing engagement.
As noted, the deck may be made from any material. In one exemplary embodiment, the deck comprises corrugated aluminum sheet with the valleys running diagonally across the pallet. Although aluminum is in general oxidation resistant, when not anodized it can be prone to oxidation, particularly in wet environments. The corrosion is often manifested by white scaly and adherent deposits. In certain applications such as clean room or food preparation requiring direct food contact, such oxidation may not be allowable. Furthermore, as a reactive metal aluminum is prone to chemical attack, for instance, from alkalis such as sodium hydroxide, from certain acids, and from salts. In diverse use, pallets may be subjected to such types of environments which can cause corrosion. There can be weakening through metal loss; the resultant rough surfaces can be hard to clean and have a poor appearance. Thus, there is a need to protect the deck, and to provide a means which makes the deck easier to clean. Accordingly, when using such deck materials, it is often advantageous to utilize a coating.
Although this invention has been shown and described with respect to a exemplary embodiments, it will be understood by those skilled in this art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.