DE2722315A1 - TRANSPORT PALLET MADE OF PLASTIC - Google Patents

Description

PATENT LAWYERS DR. A. VAN DER WERTH DR. FRANZ LEDERER REINER F. MEYER DlPL-ING. (1934-1974) DIPL-CHEM. DIPL-ING.

SOLVAY & CIE.
Rue du Prince Albert, 33 B-1050 Brussels / Belgium

8000 MONKS 80

UJClLE-GRAHN-STlMSSf

TEUFON: (089) 472 * 47 TELEX: 524624 LEOER O TELEGR .: UOERPATtNT

May 4th 1977 p.76 / 23 M / Hö

Plastic transport pallet

The invention relates to a transport pallet made of plastic, which has a very good resistance to bending as well has an increased long-term resistance to creep under load.

For a certain time it has already been proposed / to replace the conventional transport pallets made of wood by pallets made of plastic in order to benefit from the advantageous properties of the plastics and in particular their resistance to aging.

The plastic pallets generally have a plurality of feet, in the most common case nine feet, which are connected to one another via at least one full panel or a cross grating forming a perforated plate, which form a supporting surface of the pallet. Frequently standing

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the feet are connected to one another via two solid or openwork panels, each of which forms a supporting surface, the distance between these panels allows the insertion of the forks with which the transport devices are equipped are.

These pallets are generally manufactured using injection molding technology; Can also be used by other techniques as well Use can be made, such as extrusion blow molding, thermoforming or compression deformation.

In terms of economic value competitiveness with Wooden pallets may only be used between 12 and Weigh 20 kg and still have to be able to withstand normal loads. Usually the Pallets to be able to carry loads in the order of 1 to 2 t that are evenly distributed or more or are arranged less localized and which are set off in any way. The pallets can be flat or uneven Support surfaces or on locally arranged supports, for example on the forks of pallet trucks or the angle profiles that warehouses are equipped with.

The currently used for the production of copper pallets on most of the material used is high density polyethylene, both in compact and expanded form; it can be reinforced with fiberglass or other filler material. Polypropylene or polystyrene can be used in the same way will.

Regardless of the material used for the production of plastic pallets is selected, there is no possibility of certain significant mechanical defects of this type of pallet overcome, namely a lack of flexural rigidity and a very clear tendency towards long-term creeping.

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Attempts have already been made to overcome these shortcomings, in particular by using reinforcement fittings made of wood or steel which are embedded in the walls of the pallets. However, there is so far to achieve a satisfactory reinforcing the need for significant hardware stiff zuhilfe having to take with a resultant significant increase in weight of the pallets and a substantial increase in their cost price.

Now it has been developed from plastic reinforced shipping pallet that an economic solution to the problems of mechanical resistance provides this pallet type, without this being an excessively heavy training these pallets is caused.

The invention thus relates to a transport pallet made of plastic with a plurality of feet which are connected to one another via at least one panel forming a supporting surface of the pallets, which is reinforced by at least one fitting that forms a closed loop and rests on at least two feet the pallet rests when the latter is under load.

According to the invention, very light fittings can be provided: their total weight can be less than 50% of the total weight of the pallet and is preferably less than 30%. The weight of the fittings is generally between 1 and 6 kg.

These lightweight fittings can advantageously, if they are only subjected to tension, consist in cables made of steel, for example. Other materials of high resistance, such as glass or carbon fibers, can be used in the same way.

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Another type of light fitting consists of profiles, for example made of steel and, for example, with a U- or T-shaped corner cross-section or in tubular profiles with, for example, a circular or rectangular cross-section.

When the pallets according to the invention are under load, transferable Fittings that are supported on feet are a burden to this. It is therefore useful to design and dimension these feet depending on the loads, which they must be able to transmit under load.

The number and shape of the fittings can vary considerably. However, in order to be effective, each loop must have at least one section substantially parallel to the panel forming the supporting surface, so that the on the Bending stresses acting on the pallet under load are converted into tensile or compressive forces that are generated by the loop and be absorbed by the feet.

In a preferred manner, each pallet has at least three sections in the defined manner, each with a loop are connected and are arranged parallel or orthogonally. The sections so defined are preferred arranged between the feet on which dj.e fittings to which they belong, find support.

Numerous design variants of the fittings can be envisaged in order to achieve the desired reinforcement effect reach.

In a first embodiment, the inner fitting of at least one cable in the form of a closed and be formed tensioned loop, which finds support on at least two feet of the pallet. This cable can hold up to one

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be tensioned at such a point that the panel of the pallet is under tension, or can be tensioned in a simple manner, without being under mechanical tension.

In this preferred embodiment, a single cable can be used, which has a single closed loop forms which are arranged on all along the perimeter of the pallet Feet find support.

This cable can be arranged in such a way that it is or can be displaced in openings provided in the plastic be embedded in the plastic. The diameter of this cable is generally between 2 and 12 mm and preferably between 3 and 10 mm. It can be done in an advantageous manner be equipped with a tensioner or any other means / which allows mechanical tensioning. In In the same way, it is advantageous to provide the openings in which the cable can slide with, for example, metallic guides to be equipped wherever the shear effect is great.

In the case of the pallets produced according to this first variant, the loads carried by the pallet cause tensile stresses which are transmitted by the cable to the feet of the pallet. There they lead to compressive stresses with vertical and horizontal components. The aligned along the axis of the feet vertical components are sufficiently weak undywerden generally absorbed in a simple way by these feet. In contrast, the horizontal components can be relatively large and have a tendency to bring the feet of the pallet closer together. It is therefore appropriate to design the panel of the pallet in such a way that it is able to withstand transverse compression. For this purpose it can be

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It will prove useful to provide lateral, central and diagonal cross-bars of sufficient cross-section to support the feet associate. Furthermore, use can be made of supplementary or additional reinforcements (steel, glass, wood) stiffen the board and prevent the feet from approaching. Finally, the fitting should preferably be in near the supports in a direction inclined to the bearing surface to allow the vertical components to Increase disadvantage of the horizontal components.

This direction should preferably maintain an angle of at least 15 ° to the plane of the supporting surface.

In the case of the pallets of the first variant, has the presence of the fitting in the form of a closed loop, which is tensioned under load, the consequence that a part / ful tensions the deflection experienced by the pallet is converted into compressive stresses, which in a simpler manner than that of the pallet forming plastic can be included.

The transport pallets according to the invention can be made of any Plastic and preferably made of a thermoplastic material, such as polyolefins such as high-density polyethylene and isotactic polypropylene, polystyrene, ABS polymers and dam polyvinyl chloride. Polyolefin structural foams are preferred as materials from which the pallets can be made if necessary reinforced with glass fibers or mineral fillers such as chalk, tallow or kips.

Any known method can be used for their preparation. However, the spray technique is preferred for this manufacture. In this latter case, the

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beat arranged in the form of an insert in the injection mold or attached to the molded pallets removed from their mold.

The pallets according to the invention can be used for the same applications as the wooden pallets. In addition, they are very suitable for use in the form of stored pallets because of their great longevity.

This pallet can be equipped with one or two full or openwork panels. The shape of the feet is arbitrary. In particular, tubular feet can be provided with stiffeners in the interior. Full feet can also be provided in the same way.

In another embodiment of the fitting is formed of at least one sheet, which is by means of a tension rod under tension, which is arranged in turn in such a manner that the fitting is supported on at least two feet of the pallet and that the bent portion toward the bearing surface of the Pallet is aligned.

According to a preferred Ausführungeform this variant, the tubular for pallets with nine feet is applicable, the pallet is equipped with five fittings of this type, wherein four fittings ümfangs the pallet are arranged along the and arranged at their ends on at the corners of the pallet support feet and the fifth bracket is arranged along a center line through the supporting surface of the pallet and is supported on two opposite corner feet between the feet.

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The curved area of the fitting can advantageously be a flat profile, a T-shaped profile, a curved profile or a steel rod, and the tie rod can be a profile, a rod or a steel cable. The bent part and the tie rod are connected to one another at their ends, and the unit thus formed can be embedded in the feet and
embedded in the palette.

The curved part of the fitting tries to avoid any deflection to oppose the load-bearing surface of the pallet in the event of a load.

The fitting is arranged in such a way that it does not hinder the introduction of forks from transport devices.

The curved part of the fitting can consist of a single arch or a double or multiple arch, which means one or more cross struts is reinforced.

The cross section of both the curved part and the tie rod that form the fitting can vary between 2 and 400 mm * and preferably between 4 and 100 mm ³ . The tie rod can also be equipped with means that allow the fitting to be adjusted.

The pallets according to the invention are shown schematically in the drawings shown, which show two embodiment variants, of which has been spoken of above. It goes without saying, however, that the drawings are not to be understood as restrictive, but that of course numerous design variants are possible within the scope of the present invention.

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Fig. 1 shows schematically in plan view an injection molded classic pallet 1 made of plastic with nine tubular feet 2, which are connected to each other via two plates 3 and 4, which maintain a distance from each other such that the passage of forks of lifting devices is possible.

According to the invention, the pallet 1 is also equipped with an inner fitting, which is formed by a steel cable in the form of a tensioned loop 5 with a cross section of 13 mm ^2, which is passed through the plastic forming the pallet 1. However, this cable can move freely in the plastic. In the area of the feet located at the corners, the cable traverses bent copper pipes 6 which have previously been embedded in these feet in order to prevent the cable from penetrating into the plastic at those points where the load from shear forces is high. In the vicinity of the feet located at the corners , the fitting is inclined by about 45 ° with respect to the plates 3 and 4.

By way of comparative load tests for this pallet and an identical range, but the latter without the described fitting, it has been found that the occurring in the non-reinforced pallet sag than that is four times greater than the amplified range.

Fig. 2 shows schematically a plan view and a Seitenan view of an embodiment of the pallet of Fig. 1, in which the course of the fitting 5 is changed in the form of the tensioned loop to favor the occurrence of compressive stresses in the circumferentially arranged feet.

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Fig. 3 shows schematically a plan view and a side view of an injection molded classic pallet 7 made of plastic with again nine tubular feet 8, which are connected to one another via two plates 9 and 10, which have such a spacing keep each other that the passage of forks of lifting devices is possible.

According to the second embodiment of the invention, the pallet 7 is also equipped with five fittings in the form of tensioned loops, each formed by a curved flat profile made of steel with a cross section of 150 mm ^J , which is held by means of a tie rod that is held by a round steel rod 12 is formed with a diameter of 8 mm. The total weight of the fittings is 4.6 kg, and these fittings are embedded in the plastic, with their ends being inserted into the feet of the pallet arranged on the circumference.

By comparing load tests on this pallet and an identical one Pallet, but the latter without the fittings described, has been found that the sag of the not reinforced The pallet is ten times larger than that of the reinforced pallet.

FIG. 4 schematically shows a top view and a side view of an embodiment variant of the pallet of FIG. 3, in which the Fittings have a double curved flat profile 13, which is reinforced with the help of cross braces 14 and 15.

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Claims (18)

Patent claims Transport pallet made of plastic with a multitude of feet, which are connected to one another via at least one plate in Stand connection which forms a supporting surface of the pallet, characterized in that the pallet (1; 7) with Using at least one fitting (5; 11,12; 12,13) is reinforced, which forms a closed loop and is supported on at least two feet (2; 8) of the pallet (1; 7) when it is loaded. 2. Pallet according to claim 1, characterized in that the total weight of the fittings (5; 11,12; 12,13) is less than 50% of the total weight of the pallet (1; 7). 3. Pallet according to claim 1 or 2, characterized in that the fitting (5; 11,12; 12,13) at least one substantially parallel to the plate forming the supporting surface Area owns. 4. Pallet according to claim 3, characterized in that at least three areas are provided which are essentially parallel to the plate forming the supporting surface and whose directions are parallel or run orthogonally. 5. Pallet according to claim 3 or 4, characterized in that said area is arranged between those feet on which the fitting to which the area belongs is supported. 6. Pallet according to any one of claims 1-5, characterized in that that the fitting (5; 12) is formed by a cable. - 12,709ΒΑΠ / 1Π53 ORIGINAL INSPECTED 7. Pallet according to claim 6, characterized in that the cable is tensioned such that the plate of the pallet (1; 7) is biased. 8. Pallet according to claim 6, characterized in that a single cable (5) is provided, which extends on all the circumferential side the pallet (1) arranged feet (2) is supported. 9. Pallet according to any one of claims 6-8, characterized in that that the cable is a steel cable. 10. Pallet according to claim 9, characterized in that the Cable has a diameter between 2 and 12 mm. 11. Pallet according to any one of claims 6-10, characterized in that that the cable runs through the plastic forming the pallet. 12. Pallet according to claim 11, characterized in that the cable (5) is displaceable in a guide (6). 13. Pallet according to any one of claims 6-12, characterized in that the direction of the fitting (5) in the vicinity of the supports is inclined with respect to the plane of the plate. 14. Pallet according to claim 13, characterized in that the direction of the fitting (5) forms an angle of at least 15 ° with the plane of the plate. 15. Pallet according to any one of claims 1-5, characterized in that the fitting (11,12; 12,13) is formed from at least one bow (11; 13) placed under tension by means of a tie rod (12), the tie rod is arranged such that it is supported on at least two feet (8) of the pallet (7) and the curved area (11; 13) is aligned in the direction of the supporting surface of the pallet (7). 709848/1053 - 13 - 16. Pallet according to claim 15, characterized in that it is equipped with five inner fittings (11,12; 12,13). 17. Pallet according to claim 15 or 16, characterized in that the inner fitting (11, 12; 12, 13) consists of steel. 18. Pallet according to claim 17, characterized in that the cross section of the fitting (11, 12; 12, 13) measures ^{between 4 and 100 mm 2.} 7098AR / 10 5