FR2737187A1 - PALLET WITH REINFORCED PLASTICS - Google Patents

Abstract

The pallet plastic support pegs (6) have plane external wall surfaces (12) and their internal wall surfaces (13) are provided with cylindrical hollow protuberances (14) which extend parallel to the peg axes (16). Each cylindrical protuberance comprises an internal cavity (15) which is delimited by the corresponding protuberance and by the internal face of the corresponding side wall of the peg. The pegs are formed by moulding and the cylindrical protuberances are obtained by gas injection. The mould has an external part defining a rectangular impression with an internal core provided with cylindrical cavities on its periphery.

Description

The present invention relates to a pallet with studs reinforced in

plastic material.

  There are already known plastic pallets of the type comprising an upper plate and a plurality of studs on which this plate rests, each stud being internally reinforced, for example,

by ribs or partitions.

  However, these ribs or these partitions alone are difficult to resist buckling and must be stiffened by other ribs and partitions which are perpendicular to them, which can cause problems of excess molding thickness by creating difficulties in filling the

mold cavity and mold release.

  In addition, the molds capable of forming such studs are particularly fragile, expensive and difficult to cool because they do not constitute a mass of compact steel, but are divided into

several small volumes.

  To stiffen pallet studs, it has also been proposed to shape the side walls of these studs in slots but this solution poses hygiene problems because the studs then have recesses in

  which materials can clump together.

  The present invention aims to solve in particular the drawbacks mentioned above by proposing a pallet comprising studs made of plastic material which, while being simple and economical to produce, have

  a buckling resistance equal to or greater than that of the studs already known.

  The subject of the present invention is a pallet which is characterized by the fact that it comprises plastic pads, the walls of which are provided with hollow cylindrical protuberances extending

parallel to the axis of the studs.

  Preferably, the hollow cylindrical protuberances are present on the inner faces of the studs, so as to leave a

  flat surface on the outside of the stud walls.

  The studs according to the invention can be produced by extrusion or

by molding.

  In the case of molding, the hollow cylindrical protrusions

  are advantageously carried out by additional gas injection.

  The present invention also relates to a mold for the production by molding and complementary injection of gas of a stud as described above, which is characterized by the fact that it comprises an external part defining an imprint corresponding to the shape exterior of

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  stud and a core capable of being housed in said outer part and comprising

  cylindrical cells at its periphery.

  In order to better understand the invention we will describe an embodiment given by way of non-limiting example, with reference to the accompanying drawing in which: - Figure 1 is a perspective view of a pallet according to a mode embodiment of the invention, - Figure 2 is a sectional view along II-II of a pad of the pallet of Figure 1 and - Figure 3 is a sectional view of a mold for the realization

of the stud of figure 2.

  The pallet 1 shown in the drawing comprises a plate 2 which has a flat upper face 3 capable of supporting articles which are not

  depicted deposited on the palette.

  On the underside of the plate 2, nine studs are provided,

  only five, referenced 4 to 8, are visible in FIG. 1.

  In the example shown, longitudinal members 9, 10 and 11 join the studs in rows of three, oriented along the large dimension of the pallet. In Figure 2, there is shown a cross section of the stud

  6, which is substantially identical to the other studs in the pallet.

  As can be seen in this FIG. 2, the lateral walls of the stud externally have a flat face 12 and internally a face 13

  provided with cylindrical protrusions 14.

  Each cylindrical protrusion 14 has an internal cavity which is delimited, on the one hand, by the wall of the corresponding cylindrical protuberance 14 and, on the other hand, by the internal face 13 of

  the corresponding side wall of the stud.

  The hollow cylindrical protrusions 14 extend parallel

  to the axis 16 of the stud, preferably over the entire height of the latter.

  The size and number of hollow cylindrical protrusions can be adjusted according to the buckling resistance that is

wish to confer on the studs.

  To make the stud in FIG. 2 by molding, one can use

  the mold shown in Figure 3.

  This mold comprises an outer part 17 defining a substantially rectangular imprint and an inner core 18 provided

  of cylindrical cells 19 on its periphery.

  - 3- We see that the core 18, which is made in one piece can be easily cooled during molding and that it does not have a brittleness zone. Thanks to such a mold, the cavities 15 of the stud are obtained, during molding, by complementary injection of gas into the columns of material.

  plastic in the molten state located in the cells 19 of the core 18.

  This additional gas injection process consists in sending a pressurized gas into the plastic in the molten state which has just been injected into the mold, substantially in line with the axes of the cylindrical cells of the core. The gas then propagates to the heart of the alveoli where the plastic is the most fluid, because it is the warmest there, which leads to the formation of gas channels centered substantially on the

axes of the alveoli.

  These channels constitute the cavities 15 after cooling of the

plastic material.

  We understand that such a process has, among other things, the important advantage of solving the problems of the solidity of the mold, of the filling.

  of its cavity, cooling and ejection of the pad.

  It is understood that the embodiment which has just been described has no limiting character and that it can receive all

  desirable modifications without departing from the scope of the invention.

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Claims (5)

CLAIMS.   1. Pallet characterized in that it comprises studs (6) made of plastic material, the walls (13) of which are provided with protuberances   hollow cylindrical (14) extending parallel to the axis (16) of the studs.   2. Pallet according to claim 1, characterized in that the hollow cylindrical protuberances (14) are present on the faces interior (13) of the studs (6).   3. Pallet according to any one of claims 1 and 2,   characterized in that the studs (6) are produced by extrusion.   4. Pallet according to any one of claims 1 and 2,   characterized in that the studs (6) are made by molding, the hollow cylindrical protuberances (14) being obtained by injection gas complement.   5. Mold for producing a pad of a pallet according to one   any one of claims 1 to 4, characterized in that it comprises   an external part (17) defining an imprint corresponding to the external shape of the stud that it is desired to produce and a core (18) capable of being housed in said external part (17) and comprising cells   cylindrical (19) at its periphery.