FR2715373A1 - Plastic crate. - Google Patents

Abstract

A small cage or box (10) made of plastic material, is intended particularly for the packaging and transportation of fruits and vegetables, and is pierced with holes (20) in its bottom (12) and sides (14, 16). Each hole (20) is surrounded by a thermoset projection part (22) which is oriented outwards. In at least two of the corners of the bottom (12), a projection part (22a) surrounding a hole (20a) is intended to penetrate in a vertical passage going through a corner pillar (18) of a lower adjacent box, when a plurality of such small boxes are superimposed. At least in the bottom (12) of the box, bosses (24) or a bulging distributed between the projection parts (22) are formed by thermal shaping inwards of the small box.

Description

PLASTIC CAGETTE
DESCRIPTION
The invention relates to a plastic crate intended in particular for packaging and transporting fruit and vegetables.

 There are currently different kinds of wooden, cardboard and plastic crates.

 Wooden and cardboard crates have major drawbacks in common.

 A first of these drawbacks is their permeability to water. This permeability is particularly sensitive in the case of cardboard crates, the mechanical strength of which decreases appreciably in the presence of moisture. In all cases, the permeability of wood and cardboard requires covered storage places. In addition, it significantly alters the weight of the tare constituted by each crate, contrary to the requirements of the regulations in force, which impose a fixed tare.

 Another drawback of wooden and cardboard crates stems from the multiplicity of components that constitute them. Indeed, in addition to wood or cardboard forming the main constituent of these crates, their assembly requires the use of staples and or glue. In addition, they usually contain a waterproofing product which has the function of reducing their water permeability as much as possible. In addition, paper labels are frequently stapled to wooden crates. This multiplicity of components of wooden and cardboard crates complicates their manufacture and, consequently, increases their cost. In addition, the operations necessary for the destruction of the crates after their use, with a view to recycling the materials which constitute them, are thereby seriously complicated.

 A third drawback common to wooden and cardboard crates concerns their flammable nature and the risks which result therefrom during their storage, whether empty or full.

 Finally, whether in wood or cardboard, the manufacture of existing crates results in a considerable consumption of wood, unsatisfactory for the ecology.

 In addition, the stacking of the crates during their storage is penalized by the thickness of the bottom of the crate in line with the corner pillars.

 In addition to these drawbacks common to wooden and cardboard crates, there are specific drawbacks to each of these materials.

 In the case of wooden crates, the rough structure of the raw wood of which these pallets are made risks injuring the products placed in the crates, especially when it is fruit.

 In the case of cardboard crates, it has already been indicated that their mechanical characteristics drop very significantly in the presence of moisture. It should be noted that this humidity can come from the environment as well as from the products transported in the crates.

 Another drawback specific to cardboard crates, which follows from the previous one, concerns the insufficient ventilation of the products transported in these crates.

Indeed, the limited mechanical strength of the cardboard crates practically prohibits the perforation in these crates. One of the consequences of this is that cardboard boxes cannot be used to transport certain products requiring efficient ventilation.

 Plastic crates solve practically all the problems presented jointly by wooden and cardboard crates.

 However, these crates are currently made of injection molded plastic, that is to say according to a batch process which considerably increases the cost.

 In addition, the use of injection molding results in giving the walls of the crates a grid-like structure which risks injuring the products transported, especially when it comes to fruit. In addition, the sides of the crates thus produced are rigid and risk bruising the products when they are put in place.

 Finally, the structure of the molded plastic crates gives them a vertical size comparable to that of wooden crates when the crates are stacked on pallets.

 In document WO-A-92 09488, a process has been described making it possible to manufacture crates of plastic material by extrusion. These crates are produced from at least one extruded plastic profile. In the part constituting the bottom and the four sides of the crate, this profile is in the form of a strip of plastic material in which holes of any shape are made.

Around each of the holes, a projecting part is formed in the strip, by thermoforming.

 The plastic crates thus produced do not have the drawbacks of molded plastic crates produced by injection. In fact, the continuous manufacturing permitted by extrusion makes it possible to significantly reduce the cost and even bring it to a level lower than that of wooden and cardboard crates. In addition, the structure of the crates gives their sides a certain elasticity which prevents bruising of the products transported. In addition, the vertical size of a stack of crates can be reduced compared to a stack of crates made of wood or molded plastic. An increase of approximately 10% in the filling rate can thus be achieved.

In the crates described in the document
WO-A-92 09488, the holes and the projecting parts which surround them provide satisfactory ventilation of the products transported and contribute to increasing the mechanical strength of the crate.

However, the products transported in such a crate risk being injured by the edges of the holes formed in the sides and in the bottom of the crate and the flow of water and any other liquid present in the products transported. is not certain. Furthermore, a risk of slipping or slipping of the crates when they are placed on a conveyor is not completely avoided. Furthermore, like all existing crates, the crates obtained by the process described in the document
WO-A-92 09488 are not positioned relative to each other when stacked.

 The subject of the invention is precisely a plastic crate having the main characteristics of the crate obtained by the method described in document WO-A-92 09488 and the original design of which simultaneously makes it possible to avoid any risk of injuring transported products, to ensure the efficient flow of liquids, to avoid any slipping of the crate when it is placed on a conveyor, and to facilitate the relative positioning of the crates during their stacking, without increasing the cost of these crates and without the other advantages inherent in plastic crates being eliminated.

 According to the invention, this result is obtained by means of a plastic crate comprising a rectangular bottom, four flanks and four hollow corner pillars, at least the bottom and the flanks being produced in a plastic strip which comprises holes each surrounded by a thermoformed protruding part, characterized in that the protruding parts are oriented towards the outside of the crate and that at least two of these protruding parts are formed in the bottom of the crate, in the extension of at least two of the four hollow corner pillars, so as to be able to penetrate into the hollow corner pillars of an adjacent lower crate.

 With some of the plastics likely to be used to manufacture such a crate, such as polypropylene, polyvinyl chloride, etc., the formation of the protruding parts, by thermoforming, in the bottom and in the sides of the crate, tends to deform these flat parts in the direction of thermoforming, that is to say towards the outside of the crate. Consequently, when the crates are stacked, the products placed in any crate risk being injured by the edges of the holes formed in the bottom of the adjacent upper crate. To remedy this drawback, the strip advantageously comprises, at least in the bottom of the crate, at least one thermoformed, non-perforated bulge, located between the projecting parts and oriented towards the inside of the crate.

 Depending on the case, this bulge can be unique and distributed over the entire surface located between the projecting parts, or include several bosses located between these projecting parts.

 Furthermore, the sides of the crate are advantageously elastic so that the products placed in the crate are not bruised when they are put in place.

 To perfect the mechanical strength of the sides of the crate, each of them advantageously includes an upper edge folded outwards from the crate at an angle at least equal to about 90.

 In this case, the upper edges are advantageously interrupted substantially opposite the hollow corner pillars, so that vertical angles can be placed in the corners of the crates when stacked on pallets, according to a usual technique.

 According to an original characteristic, the crate is advantageously made of a transparent or translucent plastic material. This characteristic makes it possible to easily control the products contained in a stack of pallets and in particular to know the nature, the size, the state of progress, etc., which constitutes an essential advantage compared to existing crates.

 When transporting certain products such as salads, it may be necessary to avoid photosynthesis. This then leads to the use of an opaque plastic material which can be obtained easily by dyeing the translucent plastic material, without it being necessary to place a colored protective paper in the crate.

A preferred embodiment of the invention will now be described, with reference to the accompanying drawings, in which
- Figure 1 is a perspective view showing a plastic crate according to the invention;
- Figure 2 is an enlarged view in vertical section, of the crate of Figure 1
- Figure 3 is a vertical sectional view schematically and partially illustrating the stack of three crates according to the invention; and
- Figure 4 is a perspective view showing a set of crates according to the invention stored on a pallet and held at their outside angles by vertical angles.

 In Figure 1, the reference 10 generally designates a crate made entirely of plastic, according to the invention. This crate is preferably manufactured by extrusion and / or by calendering, for example from two extruded profiles according to a process comparable to that which is described in document WO-A-92 09488. Alternatively, crate 10 can also be manufactured by extrusion and / or calendering from a single profile in the form of a flat, cut, perforated, thermoformed, folded and welded strip.

 The plastic crate of Figure 1 can also be injection molded, then thermoformed. However, the cost is then significantly higher, in particular because of the discontinuous nature of such a process.

 The crate 10 illustrated in FIG. 1 comprises a rectangular bottom 12, substantially planar, four rectangular flanks, also planar, including two lateral flanks 14 and two end flanks 16, and four hollow corner pillars 18.

 The lateral flanks 14 are parallel to each other and rise at a right angle from the two opposite lateral edges of the bottom 12 of the crate. In a comparable manner, the end flanks 16 are parallel to each other and rise at right angles from the end edges of the bottom 12. The bottom 12 like the flanks 14 and 16 are produced in a flat strip of thin plastic material (for example between approximately 0.8 mm and approximately 2 mm).

 Depending on the type of crate, the height of the lateral flanks 14 can be less (as illustrated in FIG. 1) or equal to that of the end flanks 16.

 The hollow corner pillars 18 rise vertically from the four angles of the rectangle formed by the bottom 12 of the crate, along the junctions between the lateral flanks 14 and the end flanks 16, over a height equal to that of these. The pillars 18 are hollow, that is to say that they are traversed over their entire height by a vertical passage allowing in particular to lighten them and reduce the amount of material necessary for the manufacture of the crate, as well as the short of the latter.

 Each of the hollow corner pillars 18 has in horizontal section the shape of a right triangle whose hypotenuse can be straight, as shown in Figure 1, or slightly curved. The two sides of the right angle formed by this right triangle are in contact with the sides 14 and 16 in the corresponding angle of the crate. In the embodiment illustrated in FIG. 1, the hollow corner pillars 18 are obtained by folding, in the same strip of plastic material as that in which the bottom 12 and the sides 14 and 16 of the crate are made.

 Given the thinness of the strip in which are made at least the bottom 12 and the sides 14 of the crate 10, these flat parts have a certain flexibility, or elasticity. This characteristic makes it possible not to bruise products such as fruits which are placed in the crate. Indeed, it is mainly the sides of the crate that deform, not the products it contains.

 The bottom 12 and the flanks 14 and 16 of the crate 10 according to the invention are crossed by holes 20 whose shape, dimensions and distribution can take very varied aspects. In the embodiment illustrated by way of example in FIGS. 1 and 2, the holes 20 are of circular shape and they are distributed in a network with triangular pitch over the entire surface of the bottom 12 and the sides 14 and 16. A the non-perforated area is advantageously provided on at least one of the sides 14 and 16, to allow marking of the crate, for example by screen printing. This avoids the addition of another material to the plastic material in which the crate is made.

 As illustrated in more detail in FIG. 2, each of the holes 20 is surrounded by a projecting part 22, obtained by thermoforming the strip in which the bottom 12 and the sides 14 and 16 are made. More precisely, the projecting parts 22 are oriented towards the outside of the crate with respect to the plane formed by the bottom or by the sides thereof. In the case where the holes 20 are circular, the protruding parts 22 have for example a frustoconical shape.

A different form can however be adopted without departing from the scope of the invention.

 Whether the strip constituting the bottom 12 and the sides 14 and 16 of the crate is obtained by extrusion, by calendering or by molding, the projecting parts 22 are always produced by thermoforming, so as to generate a prestress in the plastic.

 The holes 20 and the projecting parts 22 which surround them fulfill a large number of functions.

 The first of these functions is an aeration function for the products transported in the crates. It should be noted that this ventilation can practically be carried out on demand since the shape, the size and the distribution of the holes 20 can vary in very large proportions, without consequence on the mechanical strength of the crate.

 A second function fulfilled by the projecting parts 22 surrounding the holes 20 is a function of stiffening the strip constituting the bottom and the sides of the crate. This stiffening is especially important in the bottom of the crate, the deformation of which must not take on too great an amplitude when it is filled, to prevent the fruits or vegetables of a lower crate from being injured by the edges of the holes. 20 when the crates are stacked. On the contrary, the stiffening of the flanks 14 and 16 should not be too great, so that the latter retain sufficient flexibility or elasticity so as not to bruise the fruits. For this reason, the density of the holes 20 will generally be greater in the bottom 12 of the crate than on the sides 14 and 16.

 Another function results from the orientation of the protruding parts 22 towards the outside of the crate.

This characteristic makes it possible to prevent the products contained in the crate from being in contact with the edges of the holes 20. Consequently, any risk of seeing these products injured by these edges is avoided. It should be noted that the shapes and dimensions of the holes 20 can be different depending on the type of product transported in the crate and in particular according to the size of this product, so that the risk of the aforementioned injury is completely avoided in all cases.

 The holes 20 as well as the outward orientation of the projecting parts 22 which surround them also have the function of permanently facilitating the flow of water and any other liquid such as fruit treatment products and vegetables, essential for the good conservation of these.

 In addition, the edges of the holes 20 formed at the lower end of the protruding parts 22, in the bottom 12 of the crate, prevent it from sliding when it is placed on a conveyor. This characteristic is important, because the packaging of fruits and vegetables is most often carried out on conveyor belts and its absence would result in risks of skating or slipping.

 In addition, the presence of the holes 20 makes it possible to lighten the crates and to reduce the quantity of plastic material used in their manufacture, and consequently their cost.

 As shown in particular in FIG. 3, the bottom 12 of the crate has in each of its angles a hole 20a which can have the same shape and the same dimension as the holes 20 or a different shape and dimension. This hole 20a is placed in the extension of the vertical passage formed in the hollow corner pillar 18 which rises above this angle. This hole 20a allows water and the various liquids liable to enter the corner pillars to flow by gravity.

 As for the holes 20, at least two of the four holes 20a situated in the corners of the bottom 12 are surrounded by a part 22a, projecting outwards, that is to say downwards, from the bottom 12 .

 As illustrated diagrammatically in FIG. 3, this arrangement makes it possible to position and maintain the crates 10 one above the other when they are stacked. Indeed, the projecting parts 22a of each of the crates 10 then enter the vertical passage formed in the corresponding hollow corner pillar 18 of the adjacent lower crate.

 As already indicated, excessive downward deformation of the bottom 12 of the crates, when they are filled with products, would risk injuring the products contained in the adjacent lower crate when several crates are stacked. However, the production of the protruding parts 22 by thermoforming tends to cause such a deformation when certain plastics are used.

This is why it is recommended, at least in the bottom 12 and, if necessary, in the sides 14 and 16 of the crate, to produce, also by thermoforming, at least one non-perforated bulge between the protruding parts 22, this bulge being oriented towards the inside of the crate.

 In the embodiment illustrated in FIGS. 1 and 2, in which the abovementioned bulge is also produced on the sides of the crate, it is in the form of a plurality of bosses 24 situated between the protruding parts 22 and oriented towards the inside of the crate. Like the protruding parts 22, these bosses 24 can take various forms which are not limited to the spherical cap shape illustrated in FIG. 2.

 As a variant, the bulging of the bottom 12 and possibly of the sides 14 and 16 towards the inside of the crate can be distributed over the entire surface located between the protruding parts 22.

 As illustrated in FIGS. 1 to 4, each of the four flanks 14 and 16 has an upper edge 26, folded towards the outside of the crate 10 at an angle at least equal to approximately 90 ". This characteristic makes it possible to reinforce and stiffen the sides 14 and 16. It also eliminates any risk of cutting for people handling the crates.

 As shown in particular in FIGS. 1 and 4, the upper edge 26 of each of the sides 14 and 16 is interrupted before the ends of these sides, substantially opposite the hollow corner pillars 18.

The interruption is preferably gradual, that is to say beveled or rounded in order to avoid, again, any risk of cutting people handling the crates.

 This feature allows, when the crates 10 are stacked on pallets, to place at the angles of the stack thus formed four vertical angles 28 (Figure 4) facilitating the packaging of this set of crates, for example by means of a sheet flexible plastic material (not shown).

 Advantageously, the plastic material in which the crates 10 are made is a translucent or even transparent plastic material, which facilitates the control of the products stored or transported in the crates. Indeed, this characteristic makes it possible to easily check the nature of the products, their size, their state of progress, etc.

 As a variant, the plastic material in which the pallets 10 are made can also be opaque. For this purpose, it is advantageous to use a translucent plastic material dyed in the mass.

This characteristic will be advantageously used in certain particular cases of transport of products requiring protection vis-à-vis photosynthesis, such as certain salads. It therefore avoids having to place a tinted protective paper in the crate.

Claims (9)

 1. Plastic crate (10) comprising a rectangular bottom (12), four flanks (14,16) and four hollow corner pillars (18), at least the bottom and the flanks being made of a strip of plastic material which comprises holes (20) each surrounded by a thermoformed protruding part (22), characterized in that the protruding parts (22) are oriented towards the outside of the crate and that at least two (22a) of these projecting parts are formed in the bottom (12) of the crate, in the extension of at least two of the four hollow corner pillars (18), so as to be able to penetrate into the hollow corner pillars of a adjacent lower shelf.  2. Crate according to claim 1, characterized in that the strip comprises, at least in the bottom (12) of the crate, at least one thermoformed bulge (24), not perforated, located between the projecting parts (22) and oriented towards the inside of the crate.  3. Crate according to claim 2, characterized in that the bulge (24) is distributed over the entire surface located between the projecting parts (22).  4. Crate according to claim 2, characterized in that the bulge comprises several bosses (24) located between the projecting parts.  5. Crate according to any one of the preceding claims, characterized in that the flanks (14,16) are elastic.  6. Crate according to any one of the preceding claims, characterized in that each of the four flanks (14,16) has an upper edge (26) folded outwardly from the crate at an angle at least equal to approximately 90 ".  7. Crate according to claim 6, characterized in that the upper edges (26) are interrupted substantially opposite the hollow corner pillars (18).  8. Crate according to any one of the preceding claims, characterized in that it is made of transparent or translucent plastic.  9. Crate according to any one of claims 1 to 7, characterized in that it is made of opaque plastic.