Assembled load carrier and method for its repair or manufacture

Abstract

The invention relates to assembled load carriers with joints to which accessible load carrier elements such as superstructures, side parts, reinforcement elements or foot elements (10, 20, 30) are attached, wherein the connection of at least two load carrier elements (10, 20) is produced by a heat-soluble or microwave-soluble adhesive, and to a method for producing or repairing the assembled load carrier, wherein at least some of the surfaces to be joined are provided with adhesive for adhesive bonds; the connecting surfaces coated in this way are brought into contact at the connecting points, the parts to be joined are pressed against one another and the adhesive is activated, so that at least one adhesive bond is formed by setting the adhesive, which can be released if necessary, such as a necessary repair by heat exposure or microwave treatment of the at least one adhesive bond, for example in order to attach a replacement part.

Description

[0001] The invention relates to assembled load carriers, for example pallets, with: joints to which accessible load carrier elements such as superstructures, side parts, reinforcement elements or foot elements are attached, in particular also pallets.

[0002] Load carriers, as defined in DIN 30781, are load-bearing devices for combining goods into a single load unit. They are indispensable and well-known in logistics. A distinction must be made between single-use load carriers and reusable load carriers, including those made of recycled materials. For example, cardboard pallets, containers, vehicle (parts), or pressboard pallets are available, as are carrying aids such as bottle carriers and wire mesh crates made of recycled plastics. They facilitate the handling of load units and thus promote the efficiency and speed of the transport chain. In the context of the invention, a load carrier also refers to a part of a load carrier.

[0003] These load carriers—pallets, boxes, and containers—are currently mostly made of wood, wood-plastic composites (WPC), or plastic. There are also one-piece wood-plastic load carriers produced by pressing or molding wood chips with a thermally setting plastic, as described, for example, in DE2323124B, US D607174S, DE 20201310974U1, and WO2007121544A1. These require load carriers of consistent quality, which is why consistently consistent raw material qualities are required for certain pallets.

[0004] To improve waste management, it is desirable to recycle a wide variety of recycled materials—including single-use load carriers (paper pallets, wooden pallets, plastic pallets)—or, if necessary, simply repair them. Automated repair is particularly desirable.

[0005] For pallets with blocks that are handled by forklifts, typical weak points are the blocks, which are damaged by forklifts when driving underneath them. The blocks can also lose their usability due to moisture or other damage. Single-piece pallets are no longer easily repairable in this case. It is therefore advantageous to have a modular pallet design, allowing the modules to be replaced / repaired individually.

[0006] The same applies to boxes used in a recirculating process—such as vegetable crates, which are filled by producers and returned to the producers for reuse after use in retail. If these crates become damaged, they previously had to be disposed of as waste. With a modular design, a side panel, for example, can be easily replaced.

[0007] In the familiar one-piece pallets, the feet were either molded onto the upper element or produced by pressing them together with the upper deck (Werzalit, Inka) – meaning these pallets are irreparable. With EURO wooden pallets, it is common for individual blocks to be nailed to the upper deck, allowing them to be removed and replaced individually. Unfortunately, metal parts often remain in the wood material when it is disposed of at the end of its service life. During the recycling of wooden pallets, these metal parts destroy the cutting surfaces of shredders and the screws of extruders. Separating damaged pallets into blocks and upper deck is also laborious and usually done manually. There are also pallets where the flat upper element is made of a different material than the blocks.The two-piece design, in which blocks are produced separately from the upper deck, has the advantage of being easier to repair, as damaged blocks can be replaced while the rest of the pallet remains in use. For assembled pallets, it is desirable to replace the nails or to facilitate the separation of the blocks from the upper element.

[0008] It is also known to permanently glue pallet blocks to enable a wider material combination, where the pallet deck and the pallet blocks are made of different materials - for example, when moisture-resistant feet and runners are useful in a humid environment.

[0009] The problem with all glued load carriers was their repairability and also their recyclability.

[0010] It is therefore an object of the invention to avoid the disadvantages of the prior art.

[0011] This object is achieved by constructed load carriers according to claim 1 and a method for their production according to claim.

[0012] In a preferred embodiment of the load carrier, it is a built-up pallet with: a flat upper element (10) for carrying objects, with a top side (13) for carrying objects and a bottom side (14), foot-like blocks (20) on the bottom side (14) of the planar upper element, wherein each block (20) is a separate object from the planar upper element (10) and has an upper contact surface (22, 17) for the upper element (10) and a foot portion with a foot surface (24) opposite the upper contact surface (22), wherein the adhesive used for bonding is heat-soluble, preferably by microwave energy.

[0013] In the embodiment as a pallet with hollow blocks, flat runners (30) or flat connecting elements which connect several blocks to one another are fastened to the base surfaces (24) of the blocks (20), which hold the flat upper element (10) and the runners (30) parallel to one another.

[0014] It may be advantageous if the blocks are hollow and have flanges (17) on their contact surface (22) which enlarge the contact surface (22) of the block (20) with the underside (14) of the flat upper element (10).

[0015] In another embodiment, the upper element (10) has through-holes (12), wherein the contact surface (22) for the upper element (10) of each block (20) is glued beneath a through-hole (12) such that the through-hole (12) is aligned with the cavity of the block (10). This also allows a microwave probe or heating element to be inserted into the pallet.

[0016] It is advantageous if stops (16) are formed around the fastening surfaces on the underside (14) of the planar upper element (10), which stops enclose the contact surface (22) of the blocks (20) and protect the blocks (20) glued between the stops (16) against horizontal shear forces.

[0017] Often the blocks (20) glued under the openings (12) taper conically from their upper contact surface (22) to the block base surface (24), so that the pallets can be nested.

[0018] At least the flat upper element (10), possibly the blocks (20) and possibly the connecting elements or runners (30) can each consist of a single piece from a material selected from the group consisting of wood, plastic, composites, fillers, fibers and / or combinations thereof, which improves their recyclability.

[0019] A method according to the invention for producing or repairing a built-up load carrier comprises coating at least some of the surfaces to be joined with adhesive for adhesive bonds; the thus coated connecting surfaces are brought into contact at the connecting points, the elements to be joined are pressed against each other, and the adhesive is activated so that at least one adhesive bond is formed by setting the adhesive, which can be released if necessary, such as for a necessary repair, by applying heat or microwave treatment of the bonding point.

[0020] For this purpose, for example, an adhesive is used which is thermoplastic and becomes fluid through local heat exposure and can be reused if necessary.

[0021] It is also possible that the adhesive will decompose due to exposure to microwaves and the bonded area will be destroyed.

[0022] The assembled load carriers with: Joints to which accessible load carrier elements such as superstructures, side parts, reinforcement elements or foot elements are attached are characterized by the fact that the connection is made by a heat-soluble or microwave-soluble adhesive.

[0023] Because at least one bonded joint can be removed simply by applying heat or microwaves, parts of the load carrier can be disassembled and reused without mechanical damage. This not only creates a repaired load carrier, but the individual parts can also be repurposed as building material, formwork boards, or similar materials if they cannot be reused.

[0024] Such a construction allows for easy removal and replacement of damaged individual components, whereas with single-piece pallets, reuse is impossible and with assembled, nailed-together wooden pallets, solving the block connection is at least laborious.

[0025] Due to the multi-part design, the pallet can optionally feature flat runners or other connections on the base surfaces of the blocks that connect several blocks together. These connecting elements can also be glued. They hold the flat upper element and the runners parallel to each other, allow forklift forks to be inserted, and stabilize the pallet feet. To further stabilize the assembled pallet, it is advantageous to have stops around the connecting surfaces of the flat upper element surrounding the contact surface of the blocks, which protect the glued blocks against horizontal shear forces.

[0026] Horizontal attacks on blocks are particularly common, as the forklifts used to handle pallets easily collide with blocks and damage them. Therefore, additional stabilization of the glued block fastening with stops on the underside of the upper element is advisable.

[0027] To ensure good nestability, the pallets can have cutouts—i.e., through-holes in the upper element. These through-holes correspond to the dimensions of the glued-on hollow blocks, which preferably taper conically from their upper contact surface to the block base. This design allows a pallet to be stacked on top of another pallet in such a way that the conical blocks sink into the openings of the pallet below, thus reducing the space required for storage or transport when stacking pallets.

[0028] It is resource-efficient if at least the flat upper element, possibly the blocks, and possibly also the runners are each made of a single piece of a material such as plastic or wood or a composite material selected from the group consisting of plastic binders, fillers, fibers, and / or combinations thereof, whereby the fillers can be recycled materials. Such materials, or the production of such pallets from them, are known from WO2022 / 100771A2 or EP3822064A1.

[0029] The blocks can be made of a different material than the upper flat element - for example, to give them better resistance to various influences, such as moisture or impacts from forklifts.

[0030] To improve the repairability of assembled pallets and the reusability of their individual components, it is advantageous if the adhesive used to bond the blocks is microwave- or thermally detachable. These detachment processes can also be carried out automatically. Suitable adhesives are known, for example, from WO202121815A1, EP1115770B1, or EP20632926A1.

[0031] For example, a heat-releaseable two-layer adhesive system can be used, which comprises a layer of first adhesive and a layer of second adhesive that is bonded to the layer of first adhesive, wherein the layer of first adhesive comprises conductive particles, such as metal particles. These conductive particles can be heated by heat or microwave radiation, thereby releasing the thermally releasable adhesive. The first adhesive is, for example, a cured product of an adhesive composition that comprises a resin binder and the conductive particles. Other reversible adhesives have a polymer component - e.g. polyurethane or epoxides - and an additional component that has at least one functional group that can be activated by radiation energy. Upon activation, this triggers chemical destruction of the adhesive component, which degrades the adhesive. Suitable protecting groups include, for example,Organic amines that destroy polyurethane polymers. Such adhesive systems are available on the market and are used extensively.

[0032] The modular design and the use of thermally releasable adhesive enable load carriers with high repairability, whereby both damage analysis and repair can also be carried out automatically.

[0033] In a method according to the invention for producing a modular load carrier, at least some of the surfaces to be joined are coated with adhesive for adhesive bonds; the bonding surfaces coated in this way are brought into contact at the bonding points, the parts to be joined are pressed against each other, and the adhesive is activated, so that an adhesive bond is formed by setting the adhesive, which can be released if necessary by applying heat or microwave treatment of the bonding points.

[0034] In a preferred embodiment, an adhesive is used which is thermoplastic and becomes viscous at elevated temperature.

[0035] Another embodiment uses an adhesive that is decomposed by microwave exposure, whereby the charge carrier is locally or completely broken down into components.

[0036] The easy dissolution of the adhesive joints creates individual parts that can be reused, while the (damaged) load carrier can be bonded to a new element and thus repaired. Large-scale equipment such as heat chambers or ovens is usually not necessary; simple handheld devices are sufficient in many cases.

[0037] The invention is explained in more detail below with reference to exemplary embodiments and the drawing, to which it is by no means limited. The drawing shows schematically: Fig.1 a perspective view of a built pallet Fig. 2a plan view of the lower surface of the flat upper element Fig. 3 a detailed view of a skid design in longitudinal section, and Fig. 4 a side view of a cross-section through a planar upper element to be fitted with blocks

[0038] In Fig. 1 An embodiment of a built-up pallet with through-openings 12 is shown. It can be clearly seen that hollow blocks 20, which serve as the feet of the pallet, are glued to a flat upper element 10 with through-openings 12—which are square here. However, the invention is by no means limited to square openings or blocks—they can have any desired shape.

[0039] In Fig. 2The underside 14 of the flat upper element is shown, wherein in this embodiment, the stops are formed as elevations 18 around the hatched adhesive areas 19 around the openings 12 of the flat upper element 10, which are square in this embodiment. These prevent lateral displacement of the glued blocks 10 and thus increase the stability of the assembly.

[0040] As in Fig.1 - 3As shown, in a useful embodiment, a block 20 has a fastening flange on the contact surface 22, which enlarges the adhesive surface and thus improves the adhesive connection with the flat upper element 10. It is irrelevant whether the openings 12 and the blocks 20 are round, oval, or square - it is always very sensible to have flanges 17 at the upper end of the blocks on the contact surface 22 that can be activated by radiation energy. It is also useful for the blocks 20 to taper from the contact area 22 to the base surface 24, which makes the pallets nestable without skids and allows for better stacking during storage and for empty transport.

[0041] The fastening of the blocks 20 is shown schematically in Fig. 4shown in cross-section. It can be clearly seen that the through-openings 14 of the flat upper element 10 are assigned a corresponding foot part opening, wherein the block 20 has a fastening flange 17 on its upper contact surface 22, which is glued to the flat upper element 10, enlarging the adhesive surface and thus improving the bond.

[0042] The modular design of the pallet and the use of removable adhesives as a bonding agent between individual components of the assembled pallet allow for a high degree of repairability and adaptation to specific requirements. Individual blocks can be locally removed using local heat or microwave exposure and then replaced with new blocks, which are then glued in place. If necessary, adhesive residue from the removed adhesive can be removed mechanically or chemically before a new block is glued in place.

[0043] The production of a built-up load carrier is achieved by coating at least one of the surfaces to be joined with adhesive. The coated surfaces are brought into contact at the joints, and the elements to be joined are pressed against each other. The adhesive is activated—e.g., polymerized—so that an adhesive bond forms as the adhesive sets.

[0044] With a thermoplastic adhesive, bonded joints can be loosened by applying heat or microwave treatment if necessary (repair or disassembly) - and re-bonding may even be possible.

[0045] Adhesives that can be removed using microwave energy are often adhesives that contain components that heat up significantly when exposed to microwave radiation, such as metal particles or polar molecules.

[0046] These adhesives can be reusable or destroyed by the microwave energy, which requires a new application of the adhesive and, if necessary, the removal of old adhesive residues when repairing the charge carrier.

[0047] Thus, the inventive design enables resource-saving load carrier management, in which individual elements of the load carriers can be reused or replaced instead of being disposed of as previously.

[0048] While the invention has been described in detail with reference to preferred embodiments, it will be apparent to those skilled in the art that various alternatives and embodiments for carrying out the invention are possible within the scope of the claims. List of reference symbols

[0049] 10 flat upper element 12 through opening 10 14 underside of 10 16 stops, frame on 14 17 flange on 22 20 hollow block 22 upper contact surface of 20 24 foot surface of 20 30 skid

Claims

1. Assembled load carrier, with: joints to which load carrier elements such as superstructures, side parts, reinforcement elements or foot elements are attached, characterized in that the connection of at least two of the charge carrier elements is made by a heat-soluble or microwave-soluble adhesive.

2. Load carriers according to claim 1, characterized in that it is a built-up pallet with: a flat upper element (10) for carrying objects, with - a top side (13) for carrying objects and - a bottom side (14), - foot-like blocks (20) on the bottom side (14) of the flat upper element, characterized in that each block (20) is a separate object from the planar upper element (10) and has an upper contact surface (22, 17) for the upper element (10) and a foot portion with a foot surface (24) opposite the upper contact surface (22), wherein the adhesive used for bonding is heat-soluble, preferably by microwave energy.

3. Pallet according to claim 1, characterized in that flat runners (30) or flat connecting elements which connect several blocks to one another are fastened to the base surfaces (24) of the blocks (20), which hold the flat upper element (10) and the runners (30) parallel to one another.

4. Pallet according to claim 2 or 3, characterized in that the blocks are hollow and have flanges (17) on their contact surface (22) which enlarge the contact surface (22) of the block (20) with the underside (14) of the flat upper element (10).

5. Pallet according to claim 2 to 4, characterized in that the upper element (10) has through openings (12), wherein the contact surface (22) for the upper element (10) of each block (20) is glued under a through opening (12) such that the through opening (12) is aligned with the cavity of the block (10).

6. Pallet according to claim 2 to 5, characterized in thataround the fastening surfaces on the underside (14) of the flat upper element (10) stops (16) are formed, which enclose the contact surface (22) of the blocks (20) and protect the blocks (20) glued between the stops (16) against horizontal shear forces.

7. Pallet according to claim 2 to 6, characterized in that the blocks (20) glued under the openings (12) taper conically from their upper contact surface (22) to the block base surface (24), so that the pallets can be nested.

8. A load carrier according to one of the preceding claims, wherein at least one load carrier element is made in one piece from a material selected from the group consisting of plastic, binders, fillers, fibers, wood, WPC (wood-plastic composite) and / or combinations thereof.

9. Method for producing or repairing a built-up load carrier according to one of the preceding claims, characterized in thatat least some of the surfaces to be joined are coated with adhesive for adhesive bonds; the bonding surfaces coated in this way are brought into contact at the bonding points, the parts to be joined are pressed against each other, and the adhesive is activated so that at least one adhesive bond is formed by setting the adhesive, which can be removed if necessary, such as in the case of a necessary repair, by applying heat or microwave treatment of the bonding point, for example in order to attach a replacement part.

10. Method according to claim 9, characterized in that an adhesive is used which is thermoplastic and is dissolved by local heat.

11. Method according to claim 10, characterized in that the adhesive is decomposable by microwave exposure and the bonding area is destroyed by microwave exposure.

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