EP1440893A2

EP1440893A2 - Pallet provided with friction elements

Info

Publication number: EP1440893A2
Application number: EP04075140A
Authority: EP
Inventors: Alain Marcel Wambeke
Original assignee: D W Plastics NV
Current assignee: D W Plastics NV
Priority date: 2003-01-23
Filing date: 2004-01-23
Publication date: 2004-07-28
Also published as: EP1440893A3; GB0301555D0

Abstract

A plastic pallet has a substantially planar deck for carrying articles such as boxes and/or kegs, and support elements for supporting the deck. Friction elements (20), such as rubber studs, are mounted in openings (10) in the deck (2) for increasing the friction between the pallet and any prongs of a fork lift. The friction elements (20) do not protrude above the top surface of said deck (2) so that they are not damaged by any articles on the deck. In addition, the friction elements (20) may have a lower collar (22) which is not countersunk so as to rest on the bottom surface of the deck, thus avoiding any distortion of the friction elements when the pallet is carried by a fork lift.

Description

The present invention relates to pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered. More in particular, the present invention relates to a pallet formed of a plastics material and provided with a substantially planar deck for carrying articles and support elements for supporting the deck. Such pallets are widely used.
The support elements of a pallet are typically spaced in such a way that the prongs of a forklift may be received between them, thus enabling the forklift to lift and carry the pallet and its load. When a pallet is moved in this way, it is of course essential that it remains on the prongs carrying it, even when the forklift makes sudden moves or stops abruptly.
Traditionally, pallets were made of wood, providing sufficient friction between the pallet and the (metal) prongs of the forklift. Modem pallets, however, are made of plastics materials, such as HDPE (high density polyethylene) or similar materials, which provide less friction relative to metal. This creates the risk that a pallet may slip off the prongs of a fork lift when being carried, which is of course highly undesirable.
Accordingly, it has been suggested to provide a pallet wherein underneath the top deck friction elements are mounted for increasing the friction between the pallet and any prongs of a fork lift. The friction elements may, for example, be constituted by rubber studs. An example of a pallet provided with rubber studs is disclosed in Swiss Patent CH 662 998. The rectangular rubber studs have two collars which together hold the stud in a through-hole provided in the deck of the pallet. The upper, wider collar is countersunk, while the lower, narrower collar rests against the bottom surface of the deck. Although it is countersunk, the top part of the rubber stud protrudes above the top surface of the deck. In an attempt to avoid the rubber stud being damaged by the articles carried on the deck, the top part of the rubber stud has been provided with slanting side faces. It has been found, however, that the rubber studs may still be damaged by articles carried on the deck, and that this may cause the rubber stud to tear and eventually break.
Another example of a pallet provided with rubber studs is disclosed in European Patent EP 1 021 346. The substantially cylindrical rubber studs of said European Patent also have an upper, wider collar and a lower, narrower collar, both of which are countersunk in the deck. The top part of the rubber stud projects above the top surface of the deck. Although this known stud also has sloping sides to prevent being damaged by articles carried on the deck, it has been found that damage and deterioration of the rubber studs cannot be avoided. In addition, the countersunk lower part of the rubber stud can relatively easily be pushed into the opening when the pallet is carried by a forklift, thus causing further damage to the rubber stud. Also, if the lower part of the rubber stud is pushed into the opening, the stud loses its effectiveness.
It is an object of the present invention to overcome these and other problems of the Prior Art and to provide a pallet having friction elements which cannot easily be damaged and/or deformed.
It is another object of the present invention to provide a pallet which is economical.
Accordingly, the present invention provides a pallet formed of a plastics material, the pallet comprising a substantially planar deck for carrying articles and support elements for supporting the deck, friction elements being mounted in openings in the deck for increasing the friction between the pallet and any prongs of a fork lift, wherein the friction elements do not protrude above the top surface of said deck.
That is, by ensuring that the (top part of the) friction elements do not extend above the top surface of the deck, any damage caused by articles carried on the deck is substantially eliminated. This in turn ensures that the friction elements do not deteriorate and keep providing friction during the service life of the pallet.
The top part of a friction element may be flush with the top surface of the deck, or may lie below it. The opening in which a friction element is accommodated is not necessarily a through-hole and may be a cavity open to the bottom surface of the deck only.
A friction element according to the present invention preferably has two collars to hold it in place, an upper collar and a lower collar. The top collar is countersunk or otherwise accommodated in a wider portion of the opening so as to avoid the friction element protruding above the deck. The lower collar, however, preferably extends substantially entirely beyond said opening. That is, the lower collar rests against the bottom surface of the deck and is substantially entirely located below this surface. In other words, the lower collar preferably is not countersunk in order to minimise any deformation of the friction element when the pallet is carried on the prongs of a fork lift.
Preferably, the lower collar is wider than the upper collar. This maximises the effectiveness of the friction element and minimises the amount of material used as it is the lower part of the friction element which supports the pallet when carried by a forklift.
In the pallets according to the Prior Art discussed above the friction elements are inserted from above the (top) deck of the pallet. However, this makes it difficult to use a friction element having a suitably wide lower part with an associated wide lower collar. In the pallet of the present invention, therefore, it is preferred that a friction element is inserted into its respective opening from underneath the deck. The shape of the openings is preferably designed so as to facilitate the insertion, for instance by being tapered in the upward direction.
The friction elements are advantageously made of a material providing a large amount of friction relative to the (metal) prongs of a forklift or similar lifting device. Such a material is advantageously a resilient material, preferably a natural or synthetic rubber.
Most pallets have a substantially flush top deck, without any protrusions, so as to allow virtually any arrangement of articles thereon. For some applications, however, it may be advantageous to provide means for holding the articles carried on the pallet in place. Accordingly, in an advantageous embodiment of the present invention the deck is provided with protrusions for positioning articles, such as kegs. The protrusions may project from the surface of the deck and may be integral with the deck or may have been mounted on the deck, for example by inserting the ends of the protrusions into suitable holes in the deck. The protrusions may be arranged in suitable patterns to hold certain articles, such as kegs or boxes.
Although the deck may have a relatively smooth, "closed" surface, in a particularly advantageous embodiment the deck is constituted by a plurality of interconnected ribs. That is, the deck is "open" which makes it much easier to cleanse the part of the pallet underneath the deck. Also, having an "open" deck saves both weight and material without influencing the strength of the pallet to any significant extent. Thus a relatively light yet strong pallet is achieved. In such an embodiment, the openings for accommodating the friction elements may be defmed by holding tubes integrated in the deck.
The pallet of the present invention may be made of polyethelene, preferably high density polyhethylene, for example by injection moulding, preferably high pressure injection moulding.
The pallet of the present invention may further comprise an additional, lower deck on which the support elements rest. Preferably, such a lower deck is integral with the support elements and the higher deck.
The present invention further provides a kit-of-parts for forming a pallet as defmed above, and a friction element for use in a pallet as defmed above.
The present invention will further be explained below with reference to exemplary embodiments illustrated in the accompanying drawings, in which:
Fig. 1 schematically shows, in perspective, a preferred embodiment of a pallet according to the present invention;
Fig. 2 schematically shows, in cross-sectional view, a first embodiment of a friction element of the present invention;
Fig. 3 schematically shows, in cross-sectional view, a second embodiment of a friction element of the present invention;
Figs. 4a-c schematically show, in top view, details of the embodiment of a pallet shown in Fig. 1.
The pallet 1 shown merely by way of non-limiting example in Fig. 1 (as well as subsequent embodiments according to the present invention) is preferably formed of a thermoplastic or other polymeric material and is preferably, but not necessarily, formed by an injection moulding process. Engineered materials may be used, as well as a synthetic resin such as polyethylene or polypropylene with a filler added to stiffen the resin. It is contemplated that the pallet disclosed herein may be manufactured by various other moulding techniques and manufacturing processes applicable to the design and material selected, including but not limited to blow moulding, thermoforming, vacuum moulding, etc. It is further contemplated that the material from which the pallet according to the present invention is formed may include materials other than plastics and polymer blends, and may include metallic materials, such as aluminium or tin.
As illustrated in Fig. 1, pallet 1 includes a top deck 2 and a bottom deck 3 which both have an upper surface and a lower surface. The decks 2 and 3 preferably have a rectangular shape with rounded comers, but may also take other shapes, including but not limited to a square, circular, triangular or other shapes as desired or required by the use and application. Pallet 1 is preferably and generally symmetrical about at least one centreline. The upper surface of top deck 2 is preferably a substantially planar surface on which articles (not shown) can be carried. However, in the embodiment shown the top deck 2 has raised areas at the comers which may assist in positioning the articles. In addition, other selected areas of the upper surface are slightly raised to provide additional protrusions or positioning elements 9. In the example shown, these positioning elements 9 are arranged for positioning kegs, e.g. beer kegs, but it will be understood that other arrangements can be made to position other articles.
Top deck 2 and bottom deck 3 are connected by support elements 4, which preferably are integral with both decks. Between the support elements 4 apertures 8 are capable of accepting the prongs 30 of a forklift or similar device.
As can be seen, the upper surface of top deck 2 is constituted by a structure of interconnected ribs. This open structure is very strong yet light. In addition, the open structure allows the pallet 1 to be thoroughly cleansed. The pallet 1 may further be provided with a label (not shown).
In accordance with the present invention, openings 10 are provided in the (top) deck. Friction elements, which will further be explained below with reference to Fig. 2, can be accommodated in these openings 10 so as to increase the friction between the pallet 1 and the prongs 30. The increased friction prevents that the pallet moves during transport on a forklift or even slips off the prongs. As can be seen, the openings 10 are in the embodiment shown defined by tubular elements (13 in Figs. 2 and 3) which are integral with the top deck 2. The friction elements do not protrude above these tubular elements, that is, above the top deck. The openings 10 are arranged in rows which form an acute angle (in the embodiment shown of approximately 45°) relative to the prongs 30. In this way, the friction elements can be contacted from two substantially orthogonal directions.
It is noted that a similar arrangement of openings and friction elements could be made in the lower deck 3. This, however, is generally not necessary.
The exemplary friction element 20 shown in Fig. 2 has a top portion forming an upper collar 21, a bottom portion forming a lower collar 22 and a relatively narrow middle portion 23. The upper collar 21 is accommodated in a widened portion 11 of a respective opening 10 so as to be countersunk relative to the top surface of the deck 2. The upper collar 21 rests on a flange 12 provided in the opening 10. The friction element 20 is preferably substantially cylindrical, that is, it preferably has a substantially circular cross-section. However, a rectangular. hexagonal or other cross-section would also be feasible.
As can be seen, the top portion of the friction element 10 does not extend beyond the opening 10 or above the top surface of the deck, thus significantly reducing the risk of the friction element being damaged, for example by articles located on the deck (2 in Fig. 1). In fact, the top of the friction element 20 is substantially flush with the top surface of the deck.
The lower collar 22 of the friction element 20 rests against bottom surface of the deck 2, the bottom portion of the friction element being located beyond, that is below, the opening 10. By resting against the bottom surface of the deck, the risk of the friction element 20 being pushed into the opening 10 and thus becoming less effective is significantly reduced.
In the embodiment shown, the lower collar 22 is wider than the upper collar 21. This is advantageous in that the lower collar of the friction element assists in supporting the deck and should therefore be relatively large, while the upper collar merely serves to lodge the friction element in the opening 10 by engaging the flange 12. It will be understood, however, that the lower collar and the upper collar could have a substantially equal width, or that the upper collar may even be wider than the lower collar.
Having a relatively narrow upper collar, however, assists in the insertion of the friction element into the opening 10 from underneath the deck 10. This insertion from underneath, which may be carried out with robot arms or by hand, is particularly suitable for friction elements having a relatively wide bottom portion. To further facilitate said insertion, the (top part of the) friction element may be provided with a layer of grease or soap.
The embodiment of the friction element shown in Fig. 3 is similar to the one of Fig. 2 with the exception of the relative length of the tubular element 13 and hence of the opening 10. As can be seen from Fig. 3, the widened portion 11 of the opening 10 is higher than the top portion (collar 21) of the friction element. As a result, the friction element 20 is entirely located below the top surface of the deck 2, the top surface of the friction element being spaced apart from the deck surface. In this embodiment, therefore, the friction element is not flush with the deck surface.
In the embodiment of the pallet according to the invention shown in Fig. 1, raised areas 9 are provided on the top deck 2 so as to position and stabilise articles carried on the deck. In this particular embodiment the raised areas 9 are designed to position and hold kegs, such as beer kegs. To this end, the raised areas or positioning elements 9 have suitable curvatures and heights matching the articles. On the pallet of Fig. 1, eight kegs could be carried. For this purpose a first positioning element 9a, a second positioning element 9b and a third positioning element 9c are provided, as shown in Figs. 4a-c respectively, each positioning element having curved sections matching the curvature of the object to be positioned at the relative position of the positioning element.
Positioning element 9a shown in Fig. 4a is rounded so as to correspond with the rounded comers of the pallet 1 (cf. Fig. 1). Large intermediate positioning element 9b shown in Fig. 4b is used at the longer side of the pallet where, in the example shown in Fig. 1, three kegs can be arranged. Small intermediate positioning element 9c shown in Fig. 4c is used at the shorter side of the pallet where, in the example shown in Fig. 1, two kegs can be arranged.
The height of the positioning elements may be adapted to the particular articles to be carried on the pallet. In the case of kegs having an 11 mm base collar, for example, the height of the positioning elements may be approximately 15 mm.
As explained above, the positioning elements 9 (9a, 9b, 9c) are integral with the top deck 2. It will be understood that the positioning elements 9 can be used even when no friction elements 20 are present in the pallet, and that the positioning elements 9 can assume various shapes and sizes depending on the number and shape of the articles to be carried on the pallet. Conversely, friction elements 20 can also be used in the absence of any positioning elements 9, that is, when the top deck 2 is substantially flush. The pallet could be provided as a kit-of-parts which comprises a pallet body and a separate set of friction elements which may be inserted as necessary.
It will therefore be understood by those skilled in the art that the present invention is not limited to the embodiments illustrated above and that many modifications and additions may be made without departing from the scope of the invention as defined in the appending claims.

Claims

A pallet (1) formed of a plastics material, the pallet comprising a substantially planar deck (2) for carrying articles and support elements (4) for supporting the deck, friction elements (20) being mounted in openings (10) in the deck for increasing the friction between the pallet and any prongs of a fork lift, wherein the friction elements (20) do not protrude above the top surface of said deck (2).
The pallet according to claim 1, wherein a friction element (20) is provided with an upper collar (21) accommodated in a widened portion (11) of a respective opening (10) and a lower collar (22) extending substantially entirely beyond said opening.
The pallet according to claim 2, wherein the lower collar (22) is wider than the upper collar (21).
The pallet according to any of the preceding claims, wherein a friction element (20) is inserted into its respective opening (10) from underneath the deck (2).
The pallet according to any of the preceding claims, wherein the friction elements (20) are made of a resilient material, preferably a natural or synthetic rubber.
The pallet according to any of the preceding claims, wherein the deck (2) is provided with protrusions (9) for positioning articles, such as kegs.
The pallet according to any of the preceding claims, wherein the deck (2) is constituted by a plurality of interconnected ribs.
The pallet according to any of the preceding claims, made of polyethelene, preferably high density polyhethylene.
The pallet according to any of the preceding claims, made by injection moulding, preferably high pressure injection moulding.
The pallet according to any of the preceding claims, further comprising an additional, lower deck (3) on which the support elements (4) rest.
The pallet according to claim 10, wherein the lower deck (3) is integral with the support elements (4) and the higher deck (2).
A friction element (20) for use in the pallet of any of the preceding claims.
A kit-of-parts for forming a pallet according to any of claims 1-11, the kit comprising:

a pallet (1) formed of a plastics material, the pallet comprising a substantially pianar deck (2) for carrying articles and support elements (4) for supporting the deck, the deck being provided with openings (10) for accommodating friction elements (20), and

at least one friction element (20) mountable in a said opening (10) for increasing the friction between the pallet and any prongs of a fork lift,

wherein the at least one friction element (20) is designed such that it does not protrude above the top surface of said deck (2) when mounted in said opening.
A method of accommodating friction elements (20) in a pallet (1) formed of a plastics material, the pallet comprising a substantially planar deck (2) for carrying articles and support elements (4) for supporting the deck, the deck being provided with openings (10) for accommodating the friction elements (20), wherein the friction elements (20) are inserted in said openings (10) from underneath the deck (2).