GB2293161A

GB2293161A - Pallets

Info

Publication number: GB2293161A
Application number: GB9519026A
Authority: GB
Inventors: Derek Montgomery
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-09-17
Filing date: 1995-09-18
Publication date: 1996-03-20
Also published as: GB9519026D0

Abstract

A plastics pallet is stiffened by a plurality of intersecting ribs 14 preferably of semi-circular cross-section. The ribs may interconnect tapered feet 16 to allow the pallets to be nested. Circular recesses 20 may be provided at the intersections of the ribs 14, and contain labels or markings. <IMAGE>

Description

"Pallets" This invention relates to pallets.

In general terms a pallet is a portable load-carrying platform upon which articles may be placed for support by the pallet, the pallet usually being adapted to facilitate engagement with a transporter, eg a fork-lift truck. A typical pallet has an upper loadsupporting surface which is normally rectangular in plan. The upper surface is vertically spaced from a lower surface of the pallet which is ground-engaging and may serve to distribute the weight of the pallet load; alternatively, a number of pallet-supporting feet may depend from the upper surface. Such feet, or spacers connecting upper and lower surfaces, are often located to provide lateral channels into which forks of a lift truck can be extended for carriage of the pallet.

A traditional material for the construction of pallets is low-grade timber, with the strips and blocks of timber being mutually secured by nails. However, timber pallets have various practical disadvantages such that relatively low material cost is often outweighed by consequential costs arising from causes such as pallet failures, low durability, nonwashability, etc.

proposals have been made to fabricate pallets from plastics materials, but plastics pallets are either elaborately detailed complex structures with consequent high cost, or simpler structures which are less costly but which fail by reason of design deficiencies to achieve potential levels of performance.

It is therefore an object of the invention to provide a pallet which is formed partly or wholly of plastics material and which obviates or mitigates the problems of prior art pallets.

According to the present invention, there is provided a pallet formed partly or wholly of plastics material and having an upper load-supporting surface, said upper surface being stiffened by the formation therein of a plurality of stiffening ribs, said ribs mutually intersecting to provide a mutually interdependent pallet-stiffening function.

Said ribs preferably form a geodetic pattern on said upper surface. Said ribs may be semi-circular in transverse cross-section, and preferably extend downwardly from the upper surface.

The periphery of said upper surface is preferably formed with a plurality of downward protrusions shaped to impart local stiffening and anti-curling properties to the periphery of the upper surface. The plurality of downward protrusions is preferably formed as a row of regularly spaced protrusions adjacent to the outer edge of the upper surface.

The pallet preferably comprises a plurality of feet depending from the upper surface to support the upper surface at a substantially uniform height above a level floor. These feet may be individually formed each as a 'respective well in the upper surface, each well preferably having sides which mutually converge towards the base of the well whereby the pallet is stackable with like pellets. Each such well may be square or rectangular in plan, and the upper corners of the well may constitute nodes in the geodetic pattern of the stiffening ribs. Intersections of stiffening ribs may be formed as recesses in the upper surface, and may be inscribed or otherwise formed to display markings which are informative and/or decorative.

The pallet is preferably thermoformed by vacuum moulding a sheet of plastics material which has been temporarily softened, eg by heating; the material may be UV-stabilized HDPE (High Density Poly-Ethylene), and may contain recycled material. Alternatively, the pallet may be manufactured by any other plasticsforming method known per se; eg, injection moulding, rotational moulding, resin injection, polyurethane foam moulding, and glass fibre moulding. The pallet may be formed of any suitable plastics material or materials selected from all thermoforming materials, all thermoset materials, all resins, and all filled resins.

Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings wherein Fig. 1 is a plan view of a first embodiment of pallet in accordance with the present invention; Fig. 2 is a side elevation of the first embodiment; Fig. 3 is a vertical cross-section, to a much enlarged scale, of a foot forming part of the first embodiment; Fig. 4 is a transverse cross-section, to a much enlarged scale, of a stiffening rib forming part of the first embodiment; Figs. 5 and 6 are respectively a plan view and a side elevation, both to a much-enlarged scale, of an edge-stiffening protrusion forming part of the first embodiment;; Figs. 7 and 8 are respectively a plan view and a diametral cross-section, both to a much-enlarged scale, of a recessed node in the pattern of stiffening ribs forming part of the first embodiment; Fig. 9 is a plan view, to a much-enlarged scale, of another recessed node in the pattern of stiffening ribs forming part of the first embodiment; Fig. 10 is a plan view of a second embodiment of pallet in accordance with the present invention; Fig. 11 is a side elevation of the second embodiment; Fig. 12 is a side elevation of a modification of the second embodiment; and Fig. 13 is a plan view of the underside of the modification of Fig. 12.

Referring first to Figs. 1 and 2, a pallet 10 has an upper surface 12 which is stiffened by a geodetic pattern of stiffening ribs 14. The upper surface 12 is supported, in use of the pallet 10, at a uniform height above a floor (not shown) by means of a 3x3 array of feet 16 depending froni the upper surface 12. The lateral gaps between the feet 16 allow insert ion of the forks (not shown) of a fork-lift truck (not shown) for lifting and carriage of the pallet 10. The feet 16 are formed as wells in the upper surface 12, and these wells are preferably shaped to have downwardly convergent sides as shown in Figs. 2 and 3 to allow testing of stacked pallets.

As best shown in Fig. 1, the stiffening ribs 14 extend between rectilinearly non-opposite corners of adjacent ones of the wells constituting the feet 16. The stiffening ribs 14 thus form a geodetic pattern of interlocking triangles and rhomboids in which the ribs are interdependent instead of independent as in typical prior art.

A preferred form of the stiffening ribs 14 is one in which each rib 14 has a transverse cross-section which is a semi-circle extending downwardly from the upper surface 12, as particularly illustrated in Fig. 4.

When the pallet 10 is in use, with articles (not shown) loaded on the upper surface 12, the load-induced forces in the pallet 10 may cause its periphery to curl, twist, warp or buckle. To mitigate this undesirable tendency, the pallet periphery is provided with a row of regularly spaced edge-stiffening downward protrusions 18, shown to an enlarged scale in Figs. 5 (plan) and 6 (elevation). Factors such as dimensions, spacings, and shape may be varied; for example, the protrusions 18 may be rectangular as in Fig. 4 or ovoidal as in Fig. 1.

Nodes 20 in the reticule of stiffening ribs 14 may be recessed to accommodate inscriptions, labels, markings, etc which are informative and/or decorative while being protected from superficial damage by being recessed below the upper surface 12. Fig. 7 shows a possible informative marking 22, while Fig. 8 shows the crosssection of the pallet 10 in the vicinity of the node 20. Fig. 9 shows a possible decorative marking 24 located in another recessed node 20.

Other than for adherent labels (Figs. 7 and 9), all the above-described parts of the pallet 10 are preferably formed integrally, conveniently by a thermoforming process in which a single sheet of thermoplastics material (such as HDPE) is temporarily softened by heating, located over a suitable mould (not shown) and sucked down into the mould by application of a vacuum between the mould and the sheet of softened plastics.

When the plastics sheet cools to hardness, it will retain the shape imparted to it by the mould. Other plastics forming processes (known per se) may be substituted for thermoforming.

Suitable overall and detail dimensions for the pallet 10 are indicated in Figs. 1, 3, 4 and 5.

Figs. 10 (plan) and 11 (side elevation) show a pallet 100 which is a second embodiment of the present invention. Compared to the first embodiment 10 (Figs. 1-9), the second embodiment 100 has the protrusions 18 replaced by a continuous peripheral stiffening rib 118 having short 'radial' linking ribs 119 joining the peripheral rib 118 to the main geodetic pattern of stiffening ribs 114 which is essentially similar to the geodetic pattern of the first embodiment. While the ribs 114, 118, and 119 may have any suitable cross-section, they are preferably shaped in the form shown in Fig. 3 in respect of the ribs 14.

The pallet 100 may be modified in the manner now to be described with reference to Figs. 12 and 13, in order to allow the modified pallet 100 to be stacked with many layers of other pallets on top of it. The modification comprises a footing or "racking undercarriage" 130 secured to the bottom (normally pround-engaging) surface of the pallet 100.

The footing 130 is a sheet of plastics material moulded to have upwardly extending stiffening ribs 132 surrounding two cut-outs 134. A suitable material for the footing 130 is HDPE of 2 millimetres thickness.

The footing ribs 132 locate the footing 130 on the bottoms of the pellet feet 116, and the two plastics components 100 and 130 are then mutually secured, eg by ultrasonic welding.

Corner feet 136 on the footing 130 allow the driver of a fork-lift truck manoeuvring the modified pallet 100 to align successive pallets during pallet stacking operations, thereby to ensure that loaded stacks are vertical.

While certain modifications and improvements of the invention have been described above, the invention is not restricted thereto, and other modifications and variations can be adopted without departing from the scope of the invention.

Claims

1. A pallet formed partly or wholly of plastics material and having an upper load-supporting surface, said upper surface being stiffened by the formation therein of a plurality of stiffening ribs, said ribs mutually intersecting to provide a mutually interdependent pallet-stiffening function.

2. A pallet as claimed in Claim 1, wherein the ribs form a geodetic pattern on the upper surface.

3. A pallet as claimed in Claims 1 and 2, wherein the ribs are semi-circular in transverse cross section.

4. A pallet as claimed in any one of the preceding Claims wherein the ribs extend downwardly from the upper surface.

5. A pallet as claimed in any one of the preceding Claims, wherein the periphery of said upper surface is formed with a plurality of downward protrusions shaped to impart local stiffening and anti-curling properties to the periphery of the upper surface.

6. A pallet as claimed in Claim 5, wherein the plurality of downward protrusions are formed as a row of regularly spaced protrusions adjacent to the outer edge of the upper surface.

7. A pallet as claimed in any one of the preceding Claims comprising a plurality of feet depending from the upper surface to support the upper surface at a substantially uniform height above a level floor.

8. A pallet as claimed in Claim 7, wherein the feet are individually formed each as a respective well in the upper surface, each well having sides which mutually converge towards the base of the well whereby the pallet is stackable with like pellets.

9. A pallet as claimed in Claim 8, wherein each such well may be square or rectangular in plan, and the upper corners of the well constitute nodes in the geodetic pattern of the stiffening ribs.

10. A pallet as claimed in any one of the preceding Claims, wherein intersections of stiffening ribs are formed as recesses in the upper surface.

11. A pallet as claimed in any one of the preceding Claims thermoformed by vacuum moulding a sheet of plastics material which has been temporarily softened.