EP2605976A1

EP2605976A1 - Airfreight pallet

Info

Publication number: EP2605976A1
Application number: EP11738074.1A
Authority: EP
Inventors: Wouter Johannes Leedekerken
Original assignee: Airconpal BV
Current assignee: Airconpal BV
Priority date: 2010-08-16
Filing date: 2011-07-21
Publication date: 2013-06-26
Also published as: WO2012023849A1

Abstract

An airfreight pallet (1) comprising a substantially flat panel (2) having a composite structure wherein the panel is of a substantially plastic material, and substantially solid reinforcing elements (3) provided at the sides (4) of the panel wherein the reinforcing elements are substantially of a plastic material. Advantageously, the panel comprises a substantially hollow core layer (5) enclosed by a top skin layer (6) and a bottom skin layer (7).

Description

Title: Airfreight pallet

The invention relates to an airfreight pallet, in particular to an airfreight pallet that is at least partly provided of a plastic material.

Conventional airfreight pallets are mainly provided of aluminium material. Conventional aluminium airfreight pallets usually comprise an aluminium plate enclosed by hollow aluminium profiles. The aluminium plate provides for a load bearing surface and the aluminium profiles at the sides of the plate provide, amongst other, for stiffness. The aluminium profiles also provide for fixation means to allow fixation of the cargo onto the pallet.

Further, an edge of the aluminium profiles is arranged for cooperation with locking means of the aircraft to lock the pallet.

A drawback of the conventional aluminium pallets is that they are relatively heavy which may reduce the load capacity of an aircraft.

Therefore, there are developments for providing an airfreight pallet at least partly from plastic material. For example, US 2009/0095206 describes such a panel comprising a composite panel and aluminium edge profiles.

Although some weight reduction may be obtained, a drawback of these pallets can be that they are difficult to manufacture. Also, it may be difficult to obtain the required integrity, stiffness, life time, durability etc. for these pallets.

An object of the invention is to provide an airfreight pallet that obviates at least one of the above mentioned drawbacks.

Thereto, the invention provides for an airfreight pallet comprising a substantially flat panel having a composite structure wherein the panel is of a substantially plastic material, further comprising substantially solid reinforcing elements connected at the sides of the panel wherein the reinforcing elements are substantially of a plastic material.

By providing a substantially flat panel of a substantially plastic material that at its side edges is provided with substantially solid reinforcing elements of a substantially plastic material, a relatively low weight pallet can be obtained. In particular by providing substantially plastic reinforcing elements a weight reduction may be obtained compared to conventional pallets. Providing a lighter pallet may increase the load bearing capacity of an aircraft and/or may increase the handling facility and/or the handling flexibility.

An airfreight pallet is an embodiment of a unit load device (ULD). A unit load device can be an airfreight pallet or a can be an airfreight container. The pallet construction may be used as basis for a bottom construction of an airfreight container, thereby an airfreight container may be obtained that provides for weight reduction and/or handling advantages.

Unit load devices, airfreight pallets and airfreight containers need at present to fulfil the requirements of FAA technical standard order (TSO) C90 and National Aerospace Standard (NAS) 3610.

The unit load devices, airfreight pallets and airfreight containers differ from pallets and/or containers that are known for transport on land and/or on sea in that the airfreight pallets and containers are provided with a substantially flat bottom that is able to be conveyed over e.g. a roller path. Contrary to the land and sea pallets and containers, airfreight pallets and containers are not provided with support feet. Also, land and/or sea pallets and containers may have to fulfil ISO requirements for pallets and/or containers, which are different from and not applicable to airfreight unit load devices, pallets and containers.

Further, unit load devices such as airfreight pallets and containers are at their side edges arranged for cooperation with an aircraft cargo loading system. The aircraft cargo loading system comprises restraints that lock the ULD once the ULD is in place in the air cargo compartment.

The panel of the airfreight pallet is substantially flat to provide for a substantially flat upper surface as load bearing surface and a substantially flat lower surface as conveying surface. Advantageously, the panel has a composite structure such as a structure comprising a substantially hollow core layer that is enclosed by a top skin layer and a bottom skin layer. The top skin layer may provide for the upper surface of the panel as load bearing surface. The bottom skin layer may provide for the lower surface as conveying surface. The core layer is

substantially hollow to allow for sufficient weight reduction while maintaining sufficient strength and stiffness.

Various embodiments of a hollow core layer are possible. For example, the hollow core layer may be a structure comprising ribs extending between the top skin layer and the bottom skin layer. The ribs may be arranged in various patterns e.g. rectangular pattern or parallel or hexagonal, the so-called honeycomb structure, or circular or semi- circular, etc.

Alternatively, one or more corrugated panels may be provided between the top skin layer and the bottom skin layer to provide for the hollow core layer.

Typically, a substantially hollow structure comprises chambers, therefore it may also be described as a substantially open structure or as a relatively low density structure. The chambers may be filled with air or any other filling material that not substantially contributes to the stiffness and/or strength of the panel, such as foam. Preferably, the chambers are filled with air. In that case, the volume of air is substantially larger than the volume of structural material enclosing the air of the hollow core layer. For example, the hollow core layer may comprise more than 50% air, compared to structural material, preferably more than 60%, more preferably more than 70%, even more preferably more than 80%.

The panel and the reinforcing elements are substantially of plastic material. Plastic material may also comprise composite plastic material such as reinforced plastic material. Preferably, the pallet comprises thermoplastic material. Various materials are suitable for use in the airfreight pallet. For example, polypropylene, self-reinforced polypropylene, glass fiber reinforced plastic material, polyethylene, etc. may be used. Advantageously, the core layer and the skin layers are made from plastic material, so more weight reduction may be possible.

The reinforcing elements are preferably substantially solid elements to provide for sufficient stiffness and strength to withstand occurring forces during testing and/or use of the pallet. A substantially solid element is, contrary to the substantially hollow core layer, not hollow, but it has limited, few or none chambers. The volume of material of the reinforcing element is substantially larger than the volume of air enclosed by the material. The volume of material may be more than 50% of the volume of the reinforcing element, preferably more than 60%, more preferably more than 70% and even more preferably more than 80%. By providing a substantially solid reinforcing element from a substantially plastic material, optimal weight reduction may be possible while maintaining sufficient strength and/or stiffness.

The reinforcing elements may be provided at the sides of the panel as separate elements or as an element integrated to the panel. A separate reinforcing element may be attached to the panel, by mechanical and/or chemical attachment means or may be inserted in a recess prepared in the panel. Any type of attachment may be possible, for example, gluing or any other adhesive, riveting, bolting, screwing, click connection, hot melting, hot forming, hot welding, etc. A separate reinforcing element may be attached at, on or in the sides of the panel. Various embodiments are possible. When the reinforcing element is inserted in a recess prepared in the panel, the reinforcing element may be enclosed e.g. by a skin layer that provides for the required enclosure, while the skin layer may or may not be bonded or connected to the reinforcing element.

The reinforcing element may also be provided as an element integrated with the panel, e.g. integrated with the core layer of the panel. For example, since the core layer of the panel is substantially hollow comprising chambers, by filling the chambers at the sides of the panel with any

reinforcing filling material a reinforcing element at the side edges of the panel may be obtained that is integrated to the panel. Filling of the chambers may be done through holes provided in the top and/or bottom skin layer. The chambers of the hollow core may e.g. be filled with fluid material that solidifies and after solidification provides for the required strength and/or stiffness.

In an other example, the solid reinforcing elements may be integrated to the hollow core layer, by gradually increasing the density of the core layer by decreasing the volume of the chambers. By decreasing the volume of the chambers gradually, or alternatively, more abrupt, until the chambers are more or less closed such that a substantially solid structure is obtained that forms the reinforcing element.

In an other example, the reinforcing elements may be integrated to at least one of the skin layers. For example, the skin layers may be provided with a thickening at the side edges of the skin layer. Such a thickening may be positioned next to the hollow core layer and may then, in addition, close off the hollow core layer at the sides thereof. Both skin layers may be provided with a thickening that abut against each other to form the reinforcing element. Or, at least one of the core layers may be provided with a thickening corresponding with the hollow chambers of the core layer that, at the sides, fill the hollow chambers of the core layer to form a reinforcing element at the side of the panel.

In an advantageous embodiment, the reinforcing element extends along substantially a side edge of the panel, so the reinforcing element may provide along approximately the whole side edge of the panel for sufficient stiffness and/or strength. The reinforcing element may be a single element extending along approximately the length of the side edge, or may comprise multiple elements that, together, extend along approximately the length of the side edge. The panel of the airfreight pallet usually has four sides. Each of the side edges is advantageously provided with a reinforcing element that extends along substantially the length of the side edge. The corners of the panel may be covered by corner elements for protection. Advantageously, the corner elements connect the reinforcing elements around the corner of the panel. So, the corner elements can be relatively easily assembled to the panel and to the reinforcing elements to provide for a relatively neatly finished pallet.

In a preferred embodiment, the reinforcing elements are separate elements that are arranged in recesses of the panel. The recesses can be introduced into the panel upon manufacturing of the panel, or can also be introduced into the panel at a later stage, during manufacturing of the pallet. The recesses may for example be introduced by removing a part of the top or bottom skin layer and a part of the core layer, while inserting the reinforcing element in the thus created recess. The recess may thereafter be closed by an additional skin layer that may be attached to the remaining skin layer and/or to the reinforcing element by any attachment means, e.g. mechanical and/or chemical.

In a preferred embodiment, the recess is prepared in the panel from a side of the panel by removing a part of the core layer while keeping the top and bottom skin layer intact. The recess then becomes accessible from the side of the panel, so the reinforcing element can be inserted from the side of the panel into the recess. The recess can then be closed e.g. by an additional skin layer that is wrapped around the side of the panel and that can be attached to the bottom and/or top skin layer and/or to the reinforcing element by mechanical and/or chemical attachment means, such as riveting, bolting, screwing, adhesion, hot melting, hot forming, etc. Alternatively, the recess may be prepared such that the depth of the recess is larger than the depth of the reinforcing element. Once the reinforcing element is inserted into the recess, there remains some length of the top and/or bottom skin layer that is not covered by the reinforcing element. This remaining length of the top and/or bottom skin layer may be wrapped around the reinforcing element to close up the reinforcing element into the recess. The top and/or bottom skin layer may be wrapped by means of e.g. hot forming, hot melting and/or pressurization. The top and/or bottom skin layer may thus be attached to each other and/or to the reinforcing element.

In an advantageous embodiment the reinforcing element is formed correspondingly to the form of the recess. The recess may be provided with a varying depth, in particular when the recess is accessible from a side of the panel, to obtain optimal stiffening, in particular to allow for an optimal bending line and/or to obtain a more or less gradual transition from the hollow core layer to the solid reinforcing element. The varying depth may be an alternating depth, or an over the length of the side edge gradually increasing and/or decreasing depth. An alternating depth may have a wave pattern, or a block pattern, or a random pattern, or a toothed pattern etc. Many variants are possible.

The airfreight pallet is, conform applicable requirements such as NAS 3610, provided with a fixation profile. The fixation profile is usually manufactured from aluminium. By providing a substantially solid reinforcing element at the sides of the panel, the fixation profile can be relatively easily and reliably attached to the substantially solid reinforcing elements e.g. by riveting, bolting, screwing etc. The fixation profile may also be provided in a recess at a top side of the reinforcing element, such that the fixation profile may be at least partially sunk into the panel and/or reinforcing element.

The invention further relates to a method for manufacturing an airfreight pallet.

Further advantageous embodiments are represented in the dependent claims.

The invention will further be elucidated on the basis of exemplary embodiments which are represented in a drawing. The exemplary

embodiments are given by way of non-limitative illustration of the invention.

In the drawing: Fig. 1 shows a schematic perspective view of a first embodiment of an airfreight pallet according to the invention;

Fig. 2 shows a cross- section along the line A-A of Fig. 1;

Fig. 3 shows a schematic perspective exploded view of a second embodiment of an airfreight pallet according to the invention;

Fig. 4 shows a schematic perspective exploded view of a third embodiment of an airfreight pallet according to the invention;

Fig. 5a shows a schematic top view of a fourth embodiment of an airfreight pallet according to the invention;

Fig. 5b shows a schematic front view of the embodiment of Fig. 5a;

Fig. 5c shows a cross- section along the line A-A of Fig. 5a;

Fig. 5d shows a cross-section along the line B-B of Fig. 5a; and

Fig. 5e shows a detail of a side edge of a pallet of Fig. 5a.

It is noted that the figures are only schematic representations of embodiments of the invention that are given by way of non-limiting example. In the figures, the same or corresponding parts are designated with the same reference numerals.

Fig. 1 and Fig. 2 show a first embodiment of the airfreight pallet 1 according to the invention. The airfreight pallet 1 comprises a substantially flat panel 2 and reinforcing elements 3 provided at the sides 4 of the panel 2.

The flat panel 2 has a composite structure that comprises a substantially hollow core 5 that is enclosed by a top skin layer 6 and a bottom skin layer 7. In Fig. 1 the hollow core 5 is schematically shown as dotted lines. The flat panel 2 is of a substantially plastic material. Preferably, the hollow core 5, the top skin layer 6 and the bottom skin layer 7 are of a plastic material. Plastic material encompasses any type of plastics, also composite plastic materials or reinforced plastic materials and variants thereof.

Advantageously, the material provided is a thermoplastic material. The material can be polypropylene and/or a composite material comprising polypropylene. The substantially hollow core 5 is here shown as a structure comprising tubular elements 8 providing chambers 9 that are here cylindrical chambers. Of course any other element 8 may be possible, e.g. hexagonal for providing a so-called honeycomb structure, or rectangular. Alternatively, the hollow core 5 may be arranged from one or more corrugated plates. The hollow core 5 mainly comprises chambers that are basically empty, i.e. not filled with any material other than air or possibly, gas.

The reinforcing elements 3 are provided at each side 4 of the panel 2 and extend along approximately the whole side 4 of the panel 2. Alternatively, the reinforcing element 3 can extend along a part of the side 4 of the panel 2 or a number of reinforcing elements 3 may be provided along the side 4.

The reinforcing elements 3 are substantially solid, contrary to the core 5 that is substantially hollow, as can be seen in Fig. 2. The solid reinforcing elements 3 are basically deprived of cavities or hollow chambers, although few or minor cavities and/or chambers may be possible. The reinforcing elements 3 can be attached to the panel 2 e.g. by means of gluing, melting, welding etc. Alternatively and/or additionally, an additional skin layer (not shown) may be provided that overlaps partly the top skin layer 6 and the reinforcing element 3. The additional skin layer may be attached to the top skin layer 6 and the reinforcing element 3 by means of e.g. gluing, melting, welding etc.

The reinforcing element 3 is of substantially plastic material such that optimal weight reduction while maintaining sufficient strength and/or stiffness may be possible. Also here, the plastic material encompasses any type of plastics, such as composite plastic materials or reinforced plastic materials and variants thereof.

By providing a substantially solid reinforcing element 3, sufficient strength and/or stiffness can be provided at the side edges 4 of the panel 2. In addition, fixation means 10 can be relatively easily attached to the solid reinforcing element, e.g. by bolting. The fixation means 10 are, conform requirements, prescribed fixation means that usually comprise an aluminium profile that is arranged for receiving cargo fixing means to fix the cargo nets to the pallet 1. The rails 10 can be connected to the reinforcing elements 3, e.g. via a through-going bolt connection. A tapered hole or a hole with a tapered bus or a nut may be provided in the reinforcing elements 3 to receive a bolt or screw.

In this embodiment, corners 11 of the panel 2 are protected by corner elements 12. In Fig. 1 three out of four corner elements 12 are shown. The corner elements 12 are preferably arranged to connect the reinforcing elements 3. For example, the corner elements 12 can be provided with protrusion that fit in holes provided at the short ends of the reinforcing elements 3.

Fig. 3 shows a second embodiment of the airfreight pallet 1 according to the invention. In this embodiment, the reinforcing element 3 is provided as an integrated part of the hollow core 5. Chambers 9 of the hollow core 5 that are at the side edge 4 of the panel 2 are filled with a filling material 14. The filling material 14 can be e.g. a liquid filling material that solidifies in the chambers 9 to fill the chambers 9 such that at the side edges 4 of the panel 2 a reinforcing element 3 is obtained that provides for sufficient strength and/or stiffness. The filling material 14 may for example be injected into the chambers 9 via perforations 15 in the top skin layer 6. The perforations 15 may, after filling the chambers 9, remain being closed off by the filling material 14, or an additional skin layer (not shown) may be provided to cover the perforations 15 and to attach to the top skin layer 6. Such an additional skin layer may be sufficiently larger to be wrapped over the edge of the panel 2 to also attach to the bottom skin layer 7. In the solidified region of the reinforcing element 3 sufficient strength is also provided to allow easy and reliable connection of the fixation means 10. As can be seen in Fig. 3, the depth of the reinforcing element 3 varies over the length of the side 4 of the panel 2. Such a varying depth may be advantageous to obtain an optimal strength and/or stiffness. Advantageously, at the positions of the connection of the rails 10 to the panel 2, the reinforcing element extends underneath the connection positions to provide for sufficient and reliable grip of the bolt or screw as connection means.

Fig. 4 shows a third embodiment of an airfreight pallet 1 according to the invention. In this embodiment, the solid reinforcing element 3 is inserted in a recess 16 of the substantially hollow core 5. After providing the panel 2, a recess 16 is hollowed out from the core material 5. Approaching from the side edge 4 from aside, core material is removed from the core 5 to form a recess 16.

In this embodiment all core material is removed between the top layer 6 and the bottom layer 7 over the depth of the recess 16. However, in other embodiments, part of the core material may remain present between the top and the bottom skin layer over the depth of the recess 16.

The top skin layer 6 and the bottom skin layer 7 remain intact and extend over the recess 16. The reinforcing element 3 is correspondingly formed to the form of the recess 16. The recess 16 can have a constant depth, as shown here, but can also have a varying depth. After preparing the recess 16, the reinforcing element 3 can be inserted into the recess 16. The reinforcing element 3 can then be closed up into the recess 16, for example by wrapping an additional skin layer 17 to the top skin layer 6 and to the bottom skin layer 7. The additional skin layer 17 can be attached to the top skin layer 6, the bottom skin layer 7 and/or the reinforcing element 3 by means of hot forming, gluing, melting, welding etc. Although not shown in Fig. 4, the other three side edges 4 of the panel 2 are usually also provided with a reinforcing element 3. The corners 11 of the panel 2 may be protected by a corner skin layer (not shown) that is wrapped around the corner 11 and that is attached to the top skin layer 6 and the bottom skin layer 7, or such a corner skin layer may be wrapped around the corner 11 and may be attached to the additional skin layers 17 of two adjacent side edges 4. A fourth embodiment of a pallet 1 according to the invention is shown in Fig. 5. Also in this embodiment, a recess 16 is provided in the substantially hollow core 5. The recess 16 is in Fig. 5a indicated by a dashed line. As can be seen in Fig. 5a, the recess 16 has a varying depth over the length of the side edge 4. The varying depth is here in the form of a wave pattern, but can have many forms. The varying depth may vary stepwise or linearly or block patterned or toothed patterned, etc. Many possibilities for a varying depth are possible. By providing a recess with a wave patterned depth, an optimal stiffening and/or strengthening of the pallet 1 may be obtained.

The reinforcing element 3 is correspondingly shaped to the form of the recess 16, such that the reinforcing element 3 can be smoothly inserted into the recess 16 to approximately fill the recess 16. Advantageously, the recess 16 is somewhat deeper than the reinforcing element 3 such that, after insertion of the reinforcing element 3 into the recess 16 part of the top skin layer 6 and part of the bottom skin layer 7 remain uncovered by the

reinforcing element 3. The free or uncovered part of the top skin layer 6 and the bottom skin layer 7 can then be wrapped around the edge of the reinforcing element 3, e.g. by hot forming, as can be seen in Fig. 5e, to close up the reinforcing element 3 in the recess 16. In Fig. 5e the overlap between the top skin layer 6 and the bottom skin layer 7 is shown exaggerated. After hot forming, both skin layers 6, 7 will be melted to each other to form a smooth side layer 18 of the panel 2. Alternatively, one of the top skin layer or the bottom skin layer can be sufficiently large to overlap also part of the top or bottom of the panel.

The fixation means 10 can be connected to the panel 2 by means of connecting means 19, here a bolt that is screwed into a tapered bus provided in a hole into the reinforcing element 3. Due to the wave patterned reinforcing element 3, the reinforcing element 3 extends underneath the connection positions, e.g. at line A-A in Fig. 5a, to provide for a firm and reliable grip of the connection means 19. The reinforcing element 3 may retract beneath the fixation means 10 when no connection is required, e.g. at line B-B in Fig. 5a.

Corners of the panel 2 are here protected by corner elements 12 that cooperate with the reinforcing elements 3 to provide for a reliable connection with the corner elements 12. The corner elements 12 can be provided with protrusions that fit into holes of the reinforcing elements to provide for a firm connection.

The pallet 1 is provided with a substantially flat bottom to allow easy handling and conveying over e.g. roller paths in aircraft compartments as well as on air cargo handling equipment. Advantageously, the bottom skin layer 7 of the pallet 1 may be provided with a coating to provide for additional protection of the bottom skin layer 7 during the life time of the pallet 1. The coating is preferably scratch-proof and/or grating- proof.

Many variants will be apparent to the person skilled in the art. All variants are understood to be comprised within the scope of the invention as defined in the following claims.

Claims

1. An airfreight pallet comprising

- a substantially flat panel having a composite structure wherein the panel is of a substantially plastic material;

- substantially solid reinforcing elements provided at the sides of the panel wherein the reinforcing elements are substantially of a plastic material.

2. Airfreight pallet according to claim 1, wherein the panel comprises a substantially hollow core layer enclosed by a top skin layer and a bottom skin layer.

3. Airfreight pallet according to claim 1 or 2, wherein a reinforcing element extends substantially along a side edge of the panel.

4. Airfreight pallet according to any one of the preceding claims, wherein the reinforcing elements are inserted in recesses of the panel.

5. Airfreight pallet according to claim 4, wherein the recesses of the panel are accessible from the sides of the panel.

6. Airfreight pallet according to claim 4 or 5, wherein the recesses are arranged in the core layer of the panel.

7. Airfreight pallet according to any one of the claims 4 - 6, wherein the recesses have a varying depth from one position to another position along the side of the panel.

8. Airfreight pallet according to claim 7, wherein the reinforcing element is correspondingly formed to the recess.

9. Airfreight pallet according to any one of the claims 4 - 8, wherein the reinforcing elements are at least partly enclosed by a part of a skin layer of the panel.

10. Airfreight pallet according to any one of the preceding claims, wherein corner elements are provided for protecting corners of the pallet.

11. Airfreight pallet according to claim 10, wherein the corner elements connect the reinforcing elements around the corner of the panel.

12. Method for manufacturing an airfreight pallet comprising

- providing a substantially flat panel having a composite structure wherein the panel is of a substantially plastic material;

- providing substantially solid reinforcing elements at the sides of the panel wherein the reinforcing elements are substantially of a plastic material.

13. Method according to claim 12, wherein the panel comprises a substantially hollow core layer enclosed by a top skin layer and a bottom skin layer.

14. Method according to claim 12 or 13, further comprising providing at least one recess in a side of the panel along at least a part side of the panel.

15. Method according to claim 14, wherein the recesses substantially extends along the side of the panel.

16. Method according to any one of claims 13 - 15, wherein the recesses are provided in the core layer of the panel.

17. Method according to any one of claims 12 - 16, wherein the recesses have a varying depth from one position to another position along the side of the panel.

18. Method according to any one of claims 14 - 17, wherein the reinforcing elements are correspondingly formed to the recess.

19. Method according to any one of claims 14 - 18, wherein after inserting the reinforcing elements into the recesses, the reinforcing elements are at least partly enclosed by at least a part of the skin layer.