ES2337189T3 - PLASTIC PALE WITH FOAM COATED PLATE. - Google Patents

Abstract

Pallet (1) comprising at least one flat and preferably rectangular cover plate (2) and formed in one piece, as well as several support elements (4) arranged in such a way on the bottom edge of this plate coating that facilitate the insertion of the forklift fork or similar forks, in which this at least one cover plate (2) is formed from a foamed plastic material (7), characterized in that the pallet (1 ) is formed as a single piece from a plastic material and because the support elements (4) are provided with holes that run in the height direction, the support elements (4) having a cross-sectional structure (6) ) in the form of a honeycomb and not being molded of a foamed plastic material.

Description

Plastic pallet with cover plate foamed

The patent application refers to a pallet for storage and for the transport of goods according to the preamble of claim 1, as well as to a method for the manufacture of such a pallet according to the preamble of the dependent procedure claim.

Pallets for storage and for Freight and goods transport of all types are in themselves known. A pallet of this type is essentially composed of a cover plate and several support elements, for example in the form of support feet or support skates, respectively, which are arranged under this plate of coating and define a predetermined distance between the plate of coating and a support surface. These elements of support are arranged in such a way on the bottom side of the cover plate that facilitates the insertion of forklift forks or the like. In addition to these single-deck pallets, by the state of the technique known as double deck pallets are known they have a top cover plate (top cover) and a bottom cover plate (bottom cover), serving the support elements practically as spacers between the two cover plates and at the same time forming a gap for the insertion of forklift forks fork between these two cover plates. The pallets of double deck of this type offer the advantage of being able to use the same on both sides (also called pallets reversible).

Pallet Coating Plates previously described are configured of several parts, by example in the form of several slats resting on the support feet or on the support skates, respectively, or are configured As one piece. Materials normally used for pallets they are wood, metals and increasingly also plastics. The pallets of plastic offer the advantage of being relatively light and weather resistant. Other advantages of plastic pallets are the possibilities for easy cleaning and disinfection of same, so the use of pallets of this type in rooms is appreciated White or in the food industry.

On plastic pallets with plates coating configured as a single piece, for reasons of weight  they are not made in a solid way but with nerves, being arranged the support ribs on the underside of the plate of coating. For the configuration of the support nerves in the manufacturing process is provided the contours corresponding in the tool, for example in a mold for cast iron

As a consequence of the concentrations of material in the area of the feet of the support nerves and in the crossover points of the support nerves, in the process of Manufacturing appear during cooling of molten plastic liquid non-uniform contractions or contraction cavities, what which significantly reduces resistance and in this way the load capacity of the pallet and / or results in form failures geometric flat and smooth top side of the plate coating (for example in the form of cavities or grooves), being also more difficult to clean these areas. On double pallets There is also the disadvantage that they cannot be manufactured in a single sequence of operations, but the plates of upper and lower coating should be manufactured as bodies Partial separately, due to its supportive nerves, and weld each other below.

A pallet is shown in US 3 814 778 double deck made from a plastic material foamed

The object of the invention is to provide a plastic pallet that has characteristics of resistance perfected and in specifying a procedure simplified for the manufacture of a plastic pallet of this kind.

This objective is achieved according to the invention by a pallet according to claim 1, as well as by a manufacturing process according to claim 12. The respective dependent claims indicate advantageous improvements of the pallet or the process of manufacturing, respectively.

Due to the fact that at least one plate of coating and preferably both coating plates of a double deck pallets are formed of a plastic material foaming is achieved a kind of lightweight construction and yet stable and resistant. Thanks to the employment of different agents expanders for the foaming process it is possible to adjust the porosity and in this way also the carrying capacity of the cover plates. Since these cover plates molded from a foamed plastic material can do without completely supportive nerves also avoid problems and related disadvantages (as explained previously). A pallet according to the invention presents in particular cover plates with flat top sides and smooth, free of geometric faults.

In an advantageous configuration, the plates of coating are surrounded by a plastic skin that encloses the foamed plastic material, so you get a closed and preferably smooth surface that allows easy cleaning or disinfection and in which the goods and goods to transport. The plastic skin is formed advantageously of the same material as plastic and bonded foam with the same through contribution of materials. To increase the coefficient of friction, the surface of the plates Coating may be roughly finished.

To reduce weight, support elements (support feet or support skates, respectively) they are provided with holes that run in the height direction, advantageously in such a way that a structure of the cross section of the support elements similar to a honeycomb. Individual cells can advantageously present a shape rectangular, but other shapes are also possible, for example circular or polygonal. The drills are configured conveniently in such a way that they extend over the entire height of the pallet, that is to say, they cross the plate or the plates of coating, respectively, and the surfaces thereof. A Advantageous thickness for coating plates of this type is of 10 to 50 mm, preferably 20 to 40 mm, the thickness of the plate coating is in particular 30 mm, if necessary additionally with a tolerance of +/- 5 mm.

In the case of a single deck pallet, this It comprises several support elements configured as skates support or as support feet. Conveniently on the side bottom of the cover plate three rows are arranged with three feet of support in each one. Two rows extend advantageously along parallel longitudinal edges of the cover plate and the third row is arranged in what essential in the center between those. Naturally they can be also provided more than three rows or also only two rows of support elements. Similarly, a row of support feet can be formed by more than three feet of support or only by two feet of support. In a particularly advantageous pallet configuration it is provided that a support foot is arranged in the area of the geometric center of gravity of the cover plate, so that a particularly good support for the plate is achieved coating in this frequently critical area.

In an advantageous improvement of the pallet according the invention, this presents two cover plates configured  as top cover plate (top cover) and plate bottom cover (bottom cover) and spaced apart through the support elements. The two plates of coating encloses a gap with the support elements open to the side surfaces of the pallet and intended for fork lift fork insertion or Similar.

The double deck pallet presents in a particularly advantageous configuration cover plates set identically and made specularly symmetric with respect to an imaginary vertical plane of the pallet (it is that is, with respect to a plane that runs parallel to the two plates of coating also arranged in parallel between yes).

The support elements are manufactured conveniently of the same plastic material as the plates of covering. In particular it is advantageous that the pallet as a unit be configured as a single piece from this plastic material As plastic materials are used polyethylene (PE) or polypropylene (PP), being possible to have provided with these plastic materials of one or more additives such as dyes, foaming agents, agents expanders, etc.

The manufacturing process according to the invention, which should preferably be used for manufacturing of the pallets described above, provides that for the Coating plate configuration is supplied to a foundry mold the molten plastic material and provided in particular of expanding agents, this mold comprising casting at least two mold plates that form the same time a part of the mold contour (cavity). After the supply of molten plastic material to the mold contour, the plastic material solidifies on plate surfaces mold, advantageously refrigerated, which constitute the surface on the upper side and the surface on the lower side of the cover plate, so that a skin is formed around the molten plastic material and still liquid. In a second stage of the procedure increases the distance between these two mold plates, so the molten plastic material and still liquid fills due to the effect of the expanding agent the volume of foamed provided in the mold contour and forms the plate coating while previously maintaining the skin formed. Naturally, it is also possible to use more than two plates of mold to manufacture a cover plate according to the procedure described above.

The foaming effect can be favored advantageously by evacuating the mold contour in the essential simultaneous with increasing distance between plates printed.

Due to the foaming of the plastic, in particular The thermal energy contained in the liquid plastic is transformed in form energy, so the necessary cooling is reduced of the mold and a cycle time is advantageously achieved short.

Conveniently, the distance between the plates of mold increases in the factor of ten to twenty, preferably in the fifteen factor, while the mold plates move away one of other. With these numerical values it has been possible to perform in the previous tests coating plates particularly resistant.

It should be mentioned here that the procedure according to the invention, it only foams the plates of coating, while the support elements are manufactured from shape not foamed but with the honeycomb structure previously described. To make this honeycomb structure are used conveniently the corresponding cores, known by the state of the art, which are introduced into the mold in places provided for this purpose.

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It is planned to carry out the manufacture of essentially palletized by a molding procedure Injection perfected in the sense explained above.

An essential advantage of the procedure manufacturing described above is that in particular double deck pallets can now be manufactured in one sequence of operations Thanks to the suppression of the structure of nerves, now it is enough to use conventional cores that configure the cavity for insertion of the forks forklift trucks between plates covering. In this way a clear simplification is achieved of the manufacturing process compared to the state of the technique.

Other features and advantages emerge in a non-limiting way of describing an example of embodiment with reference to the figures. These are shown:

Fig. 1: Perspective view of the plate top cover of a double deck pallet.

Fig. 2: Perspective view of the plate bottom cover of double deck pallet according to the figure one.

Fig. 3: Sectional view of a plate coating of a pallet according to figure 1 or 2.

A double pallet is shown in figure 1 deck marked with 1 in a perspective view from a inclined direction from above. Pallet 1 has a plate of upper cover 2, also called upper cover, and a lower cover plate 3 also called cover lower. Cover plates 2 and 3 are configured each one with a flat and closed upper side, the sides being also lower of the same essentially configured flat and closed. Both cover plates 2 and 3 can be used as support plates for goods or goods (reversible pallet). The two cover plates 2 and 3 are arranged essentially in parallel with each other and united with each other in a way distanced by a total of nine support elements 4. These specularly shaped support plates 2 and 3 symmetrical and support elements 4 define a hollow in the form of insertion slots 5a, 5b on the side surfaces of the pallet 1, configured continuously for the entire length or width of the pallet and intended for the insertion of forklifts forklifts or the like. Naturally in a way of alternative embodiment a number may also be provided upper or lower of nine support elements 4. In the case of a single-deck pallet, support elements 4 correspond to the support feet or the support skates.

In the embodiment shown, the support elements 4 are arranged in three rows with three support elements each, finishing the support elements in the outer areas flush with the side edges of the cover plates 2 and 3. Naturally, the elements of support can be arranged in one embodiment alternative also inwardly displaced with respect to these outer edges. An individual support element 4 is arranged at the geometric point of gravity of the plates coating 2 and 3, so that a support is achieved particularly advantageous in this area, since in the pallets loaded load forces appear at this point frequently higher. The support elements 4 have holes and form a type of structure similar to a panel, extending these drills all over the pallet, that is, also by the cover plates 2 and 3 and their upper sides closed. This Honeycomb-like structure is indicated with 6 in Figures 1 and 2 and preferably serves to reduce weight, but also for avoid concentrations of material that can cause problems  related to the formation of failures above mentioned.

According to the representations in Figures 1 and 2, The pallet is manufactured as one piece. How materials are preferably use polyethylene (PE) or polypropylene (PP), when Plastic material may be added a dye. For the In addition, all the plastic materials used are suitable for recycling.

Coating plates 2 and 3 are formed by foamed plastic material. Figure 3 shows a sectional view of a top cover plate 2, being The following explanations also apply to the license plate. lower cover 3. The cover plate 2 presents in its inside a foamed plastic material and marked with 7 that is surrounded by a plastic skin 8 of the same plastic material, the skin being joined 8 by providing materials with the Foamed plastic 7. Such a sandwich structure presents, despite its reduced weight, high rigidity and strength, for what the cover plate 2 is configured in total of Very resistant shape and has a high load capacity. Only the cover plates 2 and 3 are formed from Foamed plastic material, but not supporting elements 4 They have a honeycomb-like structure. In figure 3 it shows on the left side of the image a support element 4 with honeycomb structure 6 (dashed lines).

The pallet represented in figures 1 and 2 it has for example a length of 1,200 mm, a width of 1,000 mm and a height of 165 mm.

The pallet described above must be manufactured preferably by the manufacturing process that described below and for which the claim is also claimed protection. According to this manufacturing procedure it is provided that the liquid molten plastic, which may present additives such as dyes or blowing agents for foaming, it enter the outline of a mold (cavity), presenting this mold contour parallel mold plates that form the side upper and lower side, respectively, of a plate coating 2 and 3. For the manufacture of a double pallet cover, the mold therefore comprises four of these plates of mold. The partial mold contour for a cover plate 2 or 3, defined essentially by the two mold plates, is filled in a first stage completely with molten plastic, the liquid molten plastic solidifies on the mold plates chilled forming a skin 8 around the molten plastic yet liquid.

In a second stage of work the distance between these two mold plates and in this way also the volume enclosed by the partial mold contour, foaming the molten plastic phase under the effect of the expanding agent contained in the plastic material until the volume increased and enclosed by the partial mold contour without damage to the skin 8 that has formed in the mold plates chilled. The foaming effect can be favored by application of a vacuum (evacuation), with vacuum pumps attached appropriate with the partial mold contours for the plates coating 2 and 3. After solidification, preferably in the mold, a sandwich structure has been formed with shape stability according to figure 3 in which the skin 8 has formed a closed and smooth surface around the material foamed plastic 7.

The plastic material has a temperature of approximately 220 ° C when supplied to the mold contour. Normally plastic material is not supplied additionally during the foaming process. When moving away the mold plates a on the other it increases the distance between them by a factor of approximately fifteen. When the distance between the two plates of mold during the supply of the molten plastic material is of for example 2 mm, the distance is increased for foaming at approximately 30 mm, which also corresponds to the thickness of the cover plate.

For honeycomb structure configuration 6 of the support elements 4 and also for the configuration of the insertion slots 5a and 5b are arranged in the mold the corresponding cores, the use of cores of this type belongs to the state of the art and is known to specialists. By resistance reasons, the support elements are not molded of foamed plastic material as mentioned previously.

As described above, the pallet corresponding is manufactured as a single piece in a sequence of operations, regardless of whether it is a pallet of a single deck or double deck pallet. Thanks to the manufacturing as a single piece in a sequence of operations is they get compared to manufacturing procedures known an essentially shorter cycle time and a higher performance

The manufacturing procedure above described is advantageously carried out by a machine modified injection molding.

Claims (18)

1. Pallet (1) comprising at least one flat and preferably rectangular cover plate (2) and formed in one piece, as well as several support elements (4) arranged in such a way on the lower edge of this cover plate that facilitate the insertion of forklift fork or similar forks, in which at least one cover plate (2) is formed from a foamed plastic material (7), characterized in that the pallet (1) it is formed as a single piece from a plastic material and because the support elements (4) are provided with holes that run in the height direction, the support elements (4) presenting a cross-sectional structure (6) in the form of a honeycomb and not being molded of a foamed plastic material. 2. Pallet according to claim 1 characterized in that the foamed plastic material (7) of the at least one cover plate (2) is surrounded by a plastic skin (8) and therefore has a closed surface and preferably smooth. 3. Pallet according to claim 2 characterized in that the plastic skin (8) is composed of the same material as the plastic foam (7) and is bonded with the plastic foam (7) preferably by means of material input. 4. Pallet according to claim 1, 2 or 3 characterized in that the holes are configured such that they extend over the entire height of the pallet (1). 5. Pallet according to one of the preceding claims characterized in that the thickness of the at least one cover plate (2) is 10 to 50 mm, preferably 20 to 40 mm and in particular 30 mm. 6. Pallet according to one of the preceding claims characterized in that the support elements (4) are arranged in three rows, each row preferably comprising two, in particular three support elements. 7. Pallet according to one of the preceding claims characterized in that a support element (4) is arranged in the geometric center of gravity or in the area of the geometric center of gravity of the at least one cover plate (2). 8. Pallet according to any one of the preceding claims , that the pallet is configured as reversible pallet double cover (1) comprising two cover plates (2, 3) spaced apart by supporting elements (4) enclosing a gap provided for the insertion of forklift forklifts or the like, the two covering plates (2, 3) being formed from the foamed plastic material (7). 9. Pallet according to claim 8 characterized in that the two cover plates (2, 3) are configured identically and the pallet (1) is constructed in a specularly symmetrical manner. 10. Pallet according to one of the preceding claims characterized in that the support elements (4) are formed from the same plastic material as the cover plates (2, 3). 11. Pallet according to claim 1 characterized in that the plastic material is polyethylene or polypropylene, preferably including several additives. 12. Method for manufacturing a pallet, and in particular a double-deck pallet (1) according to one of claims 1 to 11, characterized in that the molten plastic material mixed with additives is introduced in a first stage for the configuration of the support or cover plate (2, 3) in a mold contour with two mold plates spaced apart from each other and solidifies in these mold plates forming a skin, these mold plates defining decisively the partial mold contour for the cover plate (2, 3), and in a second stage the distance between these two mold plates is increased, whereby the still liquid plastic material is foamed. 13. Manufacturing method according to claim 12 characterized in that simultaneously with the increase in the distance between the mold plates a vacuum generated by vacuum pumps is established in the mold contour to reinforce the foaming effect. 14. Manufacturing method according to claim 12 or 13, characterized in that the mobile mold plates are cooled, preferably by water cooling. 15. Manufacturing method according to one of claims 12, 13 or 14 characterized in that the distance between the mold plates is increased by a factor of ten to twenty, preferably by a factor of fifteen. 16. Method according to one of claims 12 to 15, characterized in that the respective object to be manufactured is manufactured as a single piece by a sequence of operations. 17. Manufacturing method according to one of claims 12 to 16 wherein the casting mold corresponding cores are provided to mold the support elements (4) structured honeycomb and insertion slots (5a, 5b) . 18. Manufacturing process according to one of claims 12 to 17 characterized in that the manufacturing process is carried out essentially in a correspondingly modified injection molding machine.