EP0358577A1 - Pallet for storing and handling various products, and method for its manufacture - Google Patents

Abstract

Pallet, which makes it possible to carry out storing and handling of various products, which is made by moulding and comprises a plate (1), the lower part of which is associated with parallel ribs (2) which delimit spaces for the passage of forks of a handling device. It is characterised in that the basic material used to make it is a concrete, in which an additive is incorporated, which makes it possible to lighten it and to increase its mechanical characteristics. <IMAGE>

Description

The present invention relates to a new type of pallet making it possible to carry out the shopping, the handling of various products.

pallets are well known devices used in many technical fields and can be defined, in general, as assemblies serving as supports for stacked products. These devices consist essentially of a tray on which the products are arranged and which has beneath its underside passages allowing the introduction of the forks of handling equipment, such as forklifts.

To date, the pallets are generally made of wood and can be classified into two main categories, the first according to which the assembly comprises a single tray (or floor) fixed on parallel supports (battens) defining between them passage zones for the forks of the machines, the second being made up of two parallel plates connected to each other by also parallel spacers for the passage of the forks of the carriages. In addition, the pallets can include fixed or removable uprights, making it easier to hold loads or allowing the stacking of several loads without damaging the goods.

Various problems arise to date with such wooden pallets. First of all, they are of relatively high manufacturing cost and deteriorate easily during the various manipulations to which they are subject between the installation of the product leaving the production plant and the use by the consumer.

The long period which sometimes elapses between placing the product on the pallet and using it therefore results in significant financial immobilization. In addition, the pallet deteriorates rapidly, not only during handling, but also due to bad weather when the products are stored outside.

To overcome these drawbacks, it has been proposed to remove the pallets and to simply encircle the products after having possibly disposed around them a protective film. Such a solution is not satisfactory, because the strapping is difficult to perform and if it is too strong, the products can be broken. Furthermore, the last row is in direct contact with the ground and can therefore be deteriorated and finally, it is not possible to carry out recoveries on the storage site.

Now we have found, and this is what is the subject of the present invention, a new type of pallet which makes it possible to solve all of these drawbacks and which not only is simple and economical to manufacture, but moreover is very light, resistant and can possibly be used for other applications, in particular to serve as shuttering elements in the case where the pallet is used to transport building materials.

In general, the pallet according to the invention is obtained by vibrated molding and comprises, in known manner, a plate, the lower part of which is associated with parallel cleats defining spaces for the passage of the forks of the handling mandrel and it is characterized in that:
- the basic material used to make it is concrete in which an additive is incorporated which makes it light and increases its mechanical characteristics;
- the battens provided in the lower part are four in number symmetrically arranged on either side of the median plane of the support plate itself, the said battens being connected to the lower base of the plate by portions in the form of an arc reinforcing the resistance of the whole.

Such results are obtained in accordance with the invention, on the one hand by the choice of the base material forming part of the said palette and, on the other hand, by implementing a specific vibrated molding process, adapted to the starting product, the structure of the molded pallet thus produced also being suitable compared to the previous solutions.

For the production of a pallet according to the invention, not only a particular material is used, namely a concrete loaded with an additive making it possible to lighten it and more particularly an additive made up of aggregates or aggregates such as those obtained. according to the teachings of FR-A-2 499 551 but, moreover, the molding operation is carried out in a particular way, namely that, in general, initially the poured concrete is first vibrated then that, in a second step, we realize a compact mechanical level either through holes for pouring concrete into the mold, holes which, moreover, make it possible to define the cleats that the pallet comprises, or by exerting pressure on the surface of the plate (for example by a smoothing operation) , the mold being in this case positioned with the feet of the pallet down; the product is then dried in an oven and finally demolded.

According to one embodiment of the invention, the molding operation is based on the principle of compression in a hollow rectangular mold into which a quantity of concrete is poured, the volume of which equals the final liter of the pallet. In this variant, the vibration and the mechanical compaction are carried out by means of a pestle representing the underside of said pallet in negative and whose pounding action occurs during the vibration and generates the final shape of the underside of the pallet while determining the thickness of the plate and generating the rise of material in the feet or cleats.

According to a variant, the plate is fed and vibrated first, then the feet. To do this, we use a mold in two parts which intervene one after the other with a two-level drawer which feeds one mold after another. A mold representing an upside-down tray is fed by a drawer which fills it then withdraws during a first vibration. A second core mold then descends and fed by the second level of drawer, allows the establishment of the feet which are in turn vibrated and pounded. The assembly of the two half-molds (which constitute what is called a double mold) then emerges together from the top.

According to another variant in accordance with the invention, a quantity of concrete is poured, the volume of which equals the final bedding of the pallet inside a hollow rectangular mold, then a vibration operation is carried out followed by a smoothing exerting pressure on the surface of the plate, the mold being in this embodiment positioned with the feet of the pallet down.

In all cases, the molded product is then steamed before being demolded.

• - la figure 1 illustre schématiquement en perspec­tive une palette moulée réalisée conformément à l'inven­tion ;
• - la figure 2 est une vue en coupe, schématique, illustrant l'opération de moulage d'une telle palette ;
• - la figure 3 est une vue schématique partielle montrant en détail une première forme de réalisation d'un moule permettant d'obtenir une palette conforme à l'invention ;
• - la figure 4 est une vue schématique en coupe d'une variante du procédé conforme à l'invention permet­tant d'obtenir une telle palette moulée.

The invention and the advantages which it brings will however be better understood thanks to the exemplary embodiments given below by way of non-limiting illustration, which are illustrated by the appended diagrams in which:

• - Figure 1 schematically illustrates in perspective a molded pallet made in accordance with the invention;
• - Figure 2 is a schematic sectional view illustrating the molding operation of such a pallet;
• - Figure 3 is a partial schematic view showing in detail a first embodiment of a mold for obtaining a pallet according to the invention;
• - Figure 4 is a schematic sectional view of a variant of the method according to the invention for obtaining such a molded pallet.

If reference is made to the appended figures and more particularly to FIG. 1, the pallet according to the invention which is obtained by molding essentially consists of a tray, designated by the general reference (1), this tray having under his lower face higher parts in relief (2) forming a cleat. These raised parts (2) are, in accordance with the invention, four in number and are arranged symmetrically on either side of the median plane XX of the support plate (1) proper. The two intermediate battens (2a, 2b) are relatively close to said plane of symmetry XX and spaced from one another by a distance of the order of a few centimeters, while the two extreme battens (2c, 2d) are , meanwhile, arranged near the sides (3,4) of the plate (1). These cleats (2a, 2d) extend over the entire length L of the plate (1). Furthermore, the areas of connection of the cleats (2a, 2d) with the lower face (5) of the plate (1) are produced according to a curved profile reinforcing the molded assembly.

Such a pallet is obtained by molding a concrete loaded with an additive making it possible to lighten it and more particularly, of an additive consisting of aggregates or aggregates such as those obtained according to the teachings of FR-A-2 499 551 By way of example, as a molding composition, it is possible to use a concrete consisting of lignocellulosic aggregate with optionally the addition of polypropylene fibers.

This molding operation is carried out in the manner illustrated in FIGS. 2 and 3 using a mold (6) comprising, on the one hand a box (7) of actual molding with which are associated cores (8) defining the shape of the battens (2a, 2d) to be carried out. With this box (7), there is associated a plate (9) comprising elements (10) on its underside allowing, as will be seen in the following description, to carry out mechanical compaction of the cast material (11) .

According to a first method of obtaining, to produce a pallet according to the invention, to produce a pallet according to the invention, firstly, through the filling orifices (12) of the mold, the box is filled ( 7) the composition of concrete previously prepared. The filling is favored by providing chamfers (13) at the top of the filling orifices (12) formed between the cores (8) of the mold. During the filling operation, firstly, the material is subjected to a vibration transmitted to the container (6). The mold being filled with a determined quantity of material, in a second step, the plate (9) is lowered so that the pestles (10) which it has on its underside, penetrate inside the orifices ( 12) of the mold. These pestles (10) make it possible to compact the cast material.

According to a variant of the process according to the invention illustrated by FIG. 4, the pallet is obtained on the principle of compression in a hollow rectangular mold into which is poured a quantity of concrete, the volume of which equals the final bedding of said pallet. The compacting operation is obtained by means of a pestle (20) representing the underside of said pallet in negative. This pestle (20) intervenes during the vibration and generates the final shape of the underside of the pallet by determining the thickness of the plate (1) and generating the rise of material in the feet or cleats (2).

A third variant (not illustrated) consists in first supplying the plate (1) then the feet (2). To do this, we use a mold in two parts which intervene one after the other with a drawer on two levels which feed one mold after another. A mold representing an upside-down tray is fed by a drawer which fills it then withdraws during a first vibration. A second core mold then descends and fed by the second level of drawer, allows the establishment of the feet which are in turn vibrated and pounded. The set of two half-molds which constitute what is called a double mold, is then released together from above. Generally, in this variant, the mold gives the same result as the first method described, but by working in two stages, namely the plate then the cleats. Such an operating process is used to date in other fields such as for example to produce "bilayer" type paving stone products.

According to a fourth variant (not illustrated), a pallet according to the invention is produced by pouring a quantity of concrete, the volume of which equals the final littering of the pallet inside a hollow rectangular mold, the vibrating being carried out by the same way as in the previous variants. In this variant, the mold is positioned with the feet of the pallet down and, after vibration, the plate is smoothed.

In all the embodiments, in accordance with the invention, the product is dried in an oven and is then removed from the mold.

The pallets thus produced are not only very light, but also have very high resistance, in particular against impact. They can be used for the storage and transport of any type of product and are particularly suitable for handling paving stones of small dimensions which cannot fall as is the case with traditional pallets with holes.

By way of example, concerning the characteristics provided by the pallets according to the invention, it can be indicated that, from the weight point of view, for a cement dosage at 350 kilos / m3, there is a density of approximately 650 , or for an average liter of 51 liters, a weight of about 33 kilos. Furthermore, with regard to the strength of such pallets, the measurements carried out gave the following results:
- compressive strength at 28 days: 40 bars.
- flexural tensile strength at 28 days: 19.9 bars

Furthermore, it is possible to significantly improve such results, for example by making an addition of fibers, the performances being able to be increased by 20 to 25% in the two aforementioned stations.

It should also be noted, by the very fact of the design of the pallet, and taking into account the fact that the plate (1) is flat and smooth, that it can be envisaged to use them for another application, after unloading, for example as formwork elements.

Finally, it should be noted that thanks to the particular structure of the pallet in accordance with the invention, it is possible to eliminate the angles systematically which, in addition to lightening, makes it possible to obtain less aggressiveness (with regard to the cement bags for example), and a lower risk of breakage during handling.

Of course, the invention is not limited to the embodiments described above, but it covers all the variants produced in the same spirit. Thus, if in the present description, the pallets according to the invention have been shown with a full tray (1), for certain applications, it may be envisaged to open up said tray, this openwork operation being carried out during molding , for example when you want to lighten the palette.

Claims (7)

1 / Pallet for carrying out the storage and handling of various products, produced by molding and comprising a plate (1) the lower part of which is associated with parallel battens (2) defining spaces for the passage of the forks of the handling mandrel , characterized in that the basic material used to make it is concrete in which an additive is incorporated which makes it light and increases its mechanical characteristics. 2 / Pallet according to claim 1, characterized in that the cleats (2) provided at the bottom are four in number arranged symmetrically on either side of the median plane of the support plate itself, said cleats being connected to the lower base of the tray by arc-shaped portions reinforcing the resistance of the assembly. 3 / A method of obtaining a pallet according to one of claims 1 and 2 obtained by molding a concrete loaded with an additive to lighten it, characterized in that the molding operation is carried out in two time, namely that initially the poured concrete is first vibrated, then that in a second step, mechanical compaction is carried out either through the concrete pouring holes in the mold, or by a pressure exerted at the surface of the tray, and finally, an oven drying operation is carried out before removing the product from the mold. 4 / A method according to claim 3, characterized in that an amount of concrete is poured whose volume equals the final litter of the pallet inside a hollow rectangular mold, then in that a vibrating and compacting by means of a pestle representing the underside of the said pallet in negative and which intervenes by pounding during the vibration and generates the final shape of the underside of the pallet by determining the thickness of the plate (1) and generating the material rising in the feet or cleats (2). 5 / A method according to claim 3, which consists of first supplying the tray (1) then the feet (2) using a mold in two parts which intervene one after the other with a drawer on two levels which supply one mold after another, one of the molds representing the tray upside down being fed by a drawer which fills it then withdraws during a first vibration, a second mold with cores descending then being fed by the second level drawer, allowing the establishment of the feet (2) which are in turn vibrated and pounded, the two half-molds then emerging together from the top. 6 / A method according to claim 3, characterized in that an amount of concrete is poured whose volume equals the final littering of the pallet inside a hollow rectangular mold, then in that a vibration followed by a smoothing operation exerting pressure on the surface of the plate (1), the mold being positioned with the feet (2) of the pallet down. 7 / A method according to one of claims 3 to 6, characterized in that during the molding operation, it performs days in the thickness of the plate (1).

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