WO1997033798A1

WO1997033798A1 - Pallet, and method for manufacturing such a pallet

Info

Publication number: WO1997033798A1
Application number: PCT/NL1997/000122
Authority: WO
Inventors: Hubertus Gertrudis Maria Orbons; Augustinus Johannes Van Lent
Original assignee: Wavin Lash Vof
Current assignee: Wavin Lash Vof
Priority date: 1996-03-13
Filing date: 1997-03-11
Publication date: 1997-09-18
Anticipated expiration: 1998-09-13
Also published as: AU2045797A; NL1002605C2

Abstract

Pallet (1) essentially of thermoplastic plastic material, comprising a top deck (2) for carrying goods to be placed on the top deck (2), feet (5a, 5b, 5c) extending downwards from the underside of the top deck (2), which feet (5a, 5b, 5c) bound insertion channels (7, 7', 8, 8') for lifting means, and possibly a bottom deck, parallel to the top deck (2), at the underside of the feet (5a, 5b, 5c). Several elongated profiles (15) of fibre-reinforced plastic material are embedded in at least one of the decks (2) of the pallet (1), distributed over the deck concerned. The present invention also provides a method for manufacturing such a pallet (1).

Description

Pallet, and method for manufacturing such a pallet.

The present invention relates to a pallet which is manufactured substantially from thermoplastic plastic material, comprising a top deck for carrying goods to be placed on the top deck, feet extending downwards from the underside of the top deck, which feet bound insertion channels for lifting means, and possibly a bottom deck, parallel to the top deck, at the underside of the feet. The present invention also relates to a method for manufacturing such a plastic pallet. Such plastic pallets, especially made of polyethylene or polypropylene, are generally known, in particular in a form which is known as a "four-way pallet". In a four-way pallet all four of the side faces extending between the top deck and the bottom deck of the pallet each have two insertion openings and insertion channels connecting thereto for the forks of a lifting means, for example a forklift truck or a pallet truck. The pallets are generally of standard dimensions, such as 800 x 1200 mm for a so-called "Euro-pallet" or 1000 x 1200 mm for an "industrial pallet".

In a generally known application pallets loaded with goods are stored in pallet racks. In this case a pallet rests solely on two horizontal and parallel supporting bars of a pallet rack, which supporting bars are situated at a distance from each other which is only slightly smaller than the corresponding dimension of the pallet.

With the plastic pallets known until now, in the case of the abovementioned application the problem occurs that a pallet begins to sag after some time, with the risk of the pallet falling down between the supporting bars. This is caused by the creep behaviour of the plastic material of the pallet under the influence of the constant, and in principle unfavourable loading of the pallet. The sagging problem occurs particularly in the case of plastic pallets where the top deck - or both decks in the case of a double-deck pallet - is substantially composed of narrow ribs with openings between them.

The object of the present invention is to solve the abovementioned problem. A further object of the present invention is to provide a solution to the problem that goods placed on the known plastic pallets can easily slip and consequently fall off the pallet.

The present invention provides a plastic pallet according to the preamble of claim 1, which is character¬ ized in that several elongated profiles of plastic material, preferably fibre-reinforced plastic material, are embedded in at least one of the decks of the pallet, distributed over the deck concerned. The fibre-reinforced profiles preferably extend virtually from one side of the deck concerned to the opposite side of the deck concerned. Where the pallet according to the invention is being placed in the pallet rack described above, the pallet is then preferably placed in the rack in such a way that the pallet lies with its fibre-reinforced profiles crosswise over both supporting bars of the rack.

Further advantageous embodiments and a method for manufacturing the pallet according to the invention are described in the claims and the description which follows with reference to the drawing. In the drawing:

Fig. 1 shows in perspective an exemplary embodiment of a pallet according to the invention,

Fig. 2 shows a section along the line II-II in Fig. 1,

Fig. 3 shows detail A in Fig. 2 on a larger scale, and

Fig. 4 shows in cross-section the fibre-reinforced profile with anti-slip strip manufactured by co-extrusion and embedded in the rib of Fig. 3.

Figure 1 shows from the top in perspective an embodiment of a substantially block-shaped plastic four-way pallet l according to the invention, having a rectangular top deck 2 which is bounded by two pairs of two side faces 3, 3' and 4, 4' respectively which are situated opposite each other and extend parallel to each other.

The side faces 4, 4' are defined by the outer peripheral edge of the top deck 2 and three feet 5a, 5b and 5c, one on each corner of the pallet and one in the centre, and an elongated support member 6 which at the underside interconnects the feet 5a, 5b, 5c situated in line with each other. A similar construction of three feet and a support member is present in the centre between the side faces 4, 4' . This positioning of feet and support members means that two parallel insertion channels 7, 7', which are intended for receiving the forks of, for example, a forklift truck or a pallet truck, extend between the side faces 4, 4' . Two parallel insertion channels 8, 8' , which can also be used for inserting the forks of a lifting means, likewise extend between the side faces 3, 3'.

The top deck 2 of the pallet 1 is substantially constructed of ribs intersecting each other and running parallel to the side faces 3, 3' and 4, 4' of the pallet 1. Additional reinforcement ribs 11, running from an intersection of two ribs of the top deck 2 to the centre of the corresponding part of the outer peripheral edge of the top deck 2, are provided at the position of the openings of the insertion channels 7, 7' and 8, 8'. According to the present invention, provision is made for fibre-reinforced profiles to be embedded in several ribs of the top deck 2. In this example they are the ribs indicated by reference number 10, which ribs extend in a straight line along the length of the pallet 1, between the side faces 3 and 3', therefore crosswise to the insertion channels 7 and 7' of the pallet l. One or more ribs 12 not provided with a fibre-reinforced profile lie between two ribs 10 provided with such a profile.

Strips 13 of an anti-slip material, projecting slightly above the surface of the top deck 2 defined by the ribs, are also present in the surface of the top deck 2 of the pallet l. The strips 13 are provided on the ribs 10 which are provided with a fibre-reinforced profile, as will be explained below with reference to Figures 2, 3 and 4. It can be seen in Figure 2 that the ribs 10 of the top deck 2 are substantially rectangular in cross-section, with the largest dimension at right angles to the surface of the deck 2, and that a fibre-reinforced profile 15 which is substantially rectangular in cross-section is embedded in each rib 10 with the largest dimension at right angles to the surface of the deck 2. It will be clear that both the ribs 10 and the fibre-reinforced profile 15 embedded therein can also be of a totally different shape. It can also be seen in Figure 2 that a strip of anti-slip material 13 projects above the plastic material of the rib 10 in which the fibre-reinforced profile 15 is embedded, over virtually the length of the rib 10 con¬ cerned, for example over a height of approximately 1 millimetre. It can be seen in Figure 3 that a strip 13 has a cross-section which is such that said strip connects at its underside to the side of a fibre-reinforced profile 15 facing the surface of the deck 2, and from there, viewed in cross-section, widens out upwards, and near the top side has a further outward projecting edge part at each longitudinal side of the strip 13.

The pallet 1 shown in Figure 1 according to the present invention is preferably manufactured as follows:

The elongated profile 16 shown in section in Figure 4 is manufactured first in a co-extrusion process. For this purpose, a fibre-reinforced profile part 15 is extruded from thermoplastic plastic material, and a profile part 13 is extruded simultaneously from thermoplastic anti-slip material, which profile parts 13 and 15 immediately fuse together in one piece during said co-extrusion process. The fibre-reinforced profile 15 is preferably made of a thermoplastic plastic material containing chemically linked glass fibres, for example polypropylene with 30% chemically linked glass fibres, known by the trade name "Vestoleen PV 7010".

For the anti-slip profile part 13 it is preferable to use a rubber-like material, in particular a thermoplastic vulcanized material, for example such as that known by the trade name "Sarlink 3170". Two advantages are obtained by the fact that the anti-slip profile part 13 is connected by means of co- extrusion to the profile part 15. First, a very firm adhesion of the anti-slip profile part 13 to the underlying profile part 15 is obtained, so that the anti-slip profile part 13 does not become detached from the pallet 1 even after a long period of use. This adhesion is considerably stronger than if the anti-slip profile part 13 were to be set up in the mould cavity without profile part 15 and were then to adhere to the plastic material to be introduced into the mould cavity. Secondly, precisely because the anti-slip profile part 13 is immovably connected to the profile part 15, it is easy to place it at the desired position in the mould cavity and hold it firmly in place there, even when the molten plastic material is flowing with force into the mould cavity during injection moulding of the pallet.

If the sagging of the pallet is not considered to be a problem, or has been solved in a way other than with fibre-reinforced profiles in a deck of the pallet, the abovementioned advantages of providing an anti-slip profile part co-extruded with another profile part already indicate clearly that the other profile part need not necessarily be made of fibre-reinforced plastic material in order to fit anti-slip strips in this advantageous way. Therefore, it is also possible to provide a pallet in which profile parts are embedded in at least one of the decks of the pallet, distributed over the deck concerned, which profile parts have been manufactured by co-extrusion of a profile part from thermoplastic plastic material and a profile part from thermoplastic plastic material with anti-slip properties. The profile parts 16 obtained by co-extrusion are set up in a deck part of the mould cavity of a suitable mould during the manufacture of the pallet. In this case this deck part of the mould cavity is advantageously provided with grooves into which the profiles 16 fit with a part of their anti-slip profile parts 13. By subsequently introducing a suitable thermoplastic plastic material into the mould cavity, the profiles 16 are embedded in the plastic material of the pallet l in the manner shown in the figures. The plastic material can be, for example, polyethylene or polypropylene, in particular recycled plastic material used earlier. The method of manufacture described above ensures that a pallet which is reinforced against sagging and is secured against goods slipping off it can be obtained in an advantageous manner.

It will be clear that the plastic four-way pallet 1 described above is a one-part pallet, in other words the body of the pallet 1 is manufactured in a single manufacturing step from molten plastic material, unlike the most well-known plastic four-way pallets which are constructed from two pallet halves which are attached to each other.

Claims

1. Pallet (1) manufactured substantially from thermoplastic plastic material, comprising a top deck (2) for carrying goods to be placed on the top deck, feet (5a, 5b, 5c) extending downwards from the underside of the top deck, which feet bound insertion channels (7, 7', 8, 8') for lifting means, and possibly a bottom deck, parallel to the top deck, at the underside of the feet, characterized in that several elongated profiles (15) of plastic material are embedded in at least one of the decks (2) of the pallet, distributed over the deck concerned.

2. Pallet according to claim 1, in which the profiles (15) extend virtually from one side (3) of the deck concerned to the opposite side (3') of the deck concerned.

3. Pallet according to claim 1 or 2, in which the deck (2) concerned is composed substantially of ribs (10, 11,

12) , and the profiles (15) are embedded in a number of the ribs (10).

4. Pallet according to claim 3, in which the ribs (10) , with profiles embedded therein, of the deck (2) concerned are substantially rectangular in cross-section, with the largest dimension at right angles to the surface of the deck, and a profile (15) which is substantially rectangular in cross-section is embedded in each of those ribs (10) with the largest dimension at right angles to the surface of the deck.

5. Pallet according to one or more of the preceding claims, in which at least one deck (2) of the pallet is provided on the surface with strips of anti-slip material (13) projecting above the surface of the deck concerned.

6. Pallet according to claim 4, in which a strip of anti-slip material (13) connects at its underside to the side of a profile (15) facing the surface of the deck (2) concerned.

7. Pallet according to claim 5 or 6, in which the anti-slip material is a thermoplastic rubber.

8. Pallet according to one or more of the preceding claims, in which the profiles are made of a thermoplastic plastic material with glass fibres chemically linked thereto.

9. Pallet according to claim 5, in which the anti-slip material is a thermoplastic material, and the profiles are manufactured from a thermoplastic plastic material, and the strips of anti-slip material and the profiles are manufactured in one piece by co-extrusion.

10. Method for manufacturing a plastic pallet, which pallet (1) comprises a top deck (2) for carrying goods to be placed on the top deck, feet extending downwards from the underside of the top deck, and possibly a bottom deck, parallel to the top deck, at the underside of the feet, which method comprises the introduction of molten thermoplastic plastic material into a mould with a suitable mould cavity, a deck part of the mould cavity defining a deck of the pallet, characterized in that, before molten plastic material is introduced into the mould cavity, several elongated profiles (15) of plastic material are set up in a deck part of the mould cavity, which profiles are embedded in the deck part by the subsequent introduction of the molten plastic material into the mould cavity.

11. Method according to claim 10, in which several elongated profiles (16) are set up in a deck part of the mould cavity before molten plastic material is introduced into the mould cavity, which elongated profiles are composed of an elongated profile part of plastic material (15) and an elongated profile part of anti-slip material (13) immovably connected thereto over the length, the deck part of the mould cavity forming elongated grooves where the elongated profiles (16) are set up with their profile part of anti-slip material (13), so that the profile parts of anti-slip material (13) project slightly above the surface of the deck (2) concerned of the pallet.

12. Method according to claim 11, in which the elongated profile parts (16) to be set up in the mould cavity are manufactured by co-extrusion of a profile part (15) from thermoplastic plastic material and a profile part (13) from thermoplastic plastic anti-slip material.

13. Method according to one or more of claims 10 - 12, in which the profiles (15) are manufactured from polypropylene with chemically linked glass fibres.

14. Method according to one or more of claims 10 - 13, in which the profile parts of anti-slip material (13) are manufactured from a thermoplastic vulcanized material.