NZ547861A

NZ547861A - Nestable tray, blank, corresponding packaging and machine for forming one such tray

Info

Publication number: NZ547861A
Application number: NZ547861A
Authority: NZ
Inventors: Gilles Durfort; Lay Nicolas Le; Gerard Mathieu; Jean-Yves Bacques
Original assignee: Otor Sa
Priority date: 2003-11-25
Filing date: 2004-11-25
Publication date: 2010-05-28
Also published as: EP1704094B8; EP1704094A2; NZ584464A; WO2005051772A2; PL1704094T3; AU2004293224B2; AU2004293224A1; WO2005051772A3; EP1704094B1

Abstract

A tray (1) which is made from a sheet of cardboard comprising four lateral walls (2, 3, 4, 5) and a base (6). Two opposing lateral walls are each equipped with a panel (9) which is provided with a longitudinal flap (11) that is intended to form a fold which extends over part of the height of the wall, the cardboard basis weight being less than or equal to 350 g/m2. Also disclosed is a blank, a packaging and a machine used to form one such tray.

Description

New Zealand Paient Spedficaiion for Paient Number 547861 NESTABLE TRAY, BLANK, CORRESPONDING PACKAGING AND MACHINE FOR FORMING ONE SUCH TRAY Technical Field The present invention relates to a nestable tray made from a sheet of cardboard, comprising side walls and a base.

It also relates to a blank for making such a tray, a packaging item comprising layers of products produced using such a blank and a machine for forming such a tray.

The invention is applicable in particular, although not exclusively, to trays which can be stacked on top of one another for dairy products, such as plastic yoghurt containers sealed with membranes and arranged in layers of four or eight pots joined together at the top.

Background Art Any discussion of the prior art throughout the specification is not an admission that such prior art is widely known or forms part of the common general knowledge in the field.

Packaging items, for example for cheese or pots of yoghurt, which can be stacked on top of one another so as to form stacks which can be layered on a pallet, are already known.

Such stacks must first of all allow the packaging items at the bottom to withstand the compressive load of the packaging items on top and, secondly, be relatively stable in vertical terms to prevent lateral tilting. To this end use is generally made of materials made of corrugated cardboard which has sufficient compressive strength, with channels running vertically, and stacking tenons with corresponding openings, the weight of a packaging item above then being borne by the walls of the packaging item beneath.

The material is sufficiently strong to allow the packaging items to be picked up by, for example, handles hollowed out in two opposite side faces of the tray.

However, these solutions have disadvantages. The weight of the cardboard of the packaging is, for example, necessarily greater than around 400 g/m2 and in all cases 1 greater than 350 g/m2 to ensure the material is strong enough, in particular in the area of the handles.

Often, the insertion of the tenons, weak cardboard protuberances, into the openings 5 cannot completely fulfil the desired function of immobilizing and keeping the stack upright, the height of the stack of packaging being, moreover, necessarily fixed, said stack also having weak corners.

Disclosure of Invention The present invention aims to provide a tray, a blank, a packaging item and a machine for forming such a tray which meet practical needs better than those known hitherto, in particular since it makes it possible to overcome these disadvantages while minimizing the basis weight of the cardboard, all while rigidifying the tray along its length and providing strong handles which can be easily grasped by a user.

Thus, the invention affords great ease of stacking with excellent strength of the corners at the joins and at the films, at optimum cost.

Advantageously, the invention also makes it possible to nest the packaging items 20 inside one another and/or to obtain a stack height which is possibly adapted to the products with a distribution of the load over all the products.

The fact that the packaging items on top bear directly on the products beneath makes it possible, surprisingly, to be much less reliant on the mechanical strength of the walls 25 of the tray themselves in the case of products such as pots of yoghurt or jars which have sufficient compressive strength and/or which are able to withstand reversible elastic deformation.

Moreover, in one advantageous embodiment, the fact that the base of the tray is 30 bevelled unexpectedly reinforces the rigidity of the tray in the event of side impacts, which is particularly beneficial when transporting and handling the packaging.

To this end the present invention proposes, in particular, a tray made of a sheet of cardboard including four side walls and a base, characterized in that two opposite side 35 walls each include a leaf having a longitudinal flap designed to form an overlap over 2 part of the height of said leaf and in that the basis weight of the cardboard is less than or equal to 350 g/m2.

The tray thereby obtained thus has excellent torsional strength despite its low basis weight.

Advantageously, said opposite side walls each have at least one opening allowing grasping by a user, positioned underneath said overlap.

The hand and/or one or more fingers of the user will therefore be able to grasp a reinforced part of the cardboard which is particularly solid in the area of the overlap, despite being made of cardboard with a low basis weight, while allowing, in a particular embodiment, excellent stacking of the trays by nesting in one another.

Advantageous embodiments also offer one and/or other of the following arrangements: the tray has a frustopyramidal longitudinal and/or cross section allowing said tray to nest at least partially in a lower tray; the lower part of each of the side walls forms a bevelled face inclined toward the central part of the tray allowing said tray to nest at least partially in a lower tray; or the lower part of each of the side walls forms a bevelled face inclined toward the vertical part of the tray allowing said tray to nest at least partially in a lower tray.

The base thus has a transversely and longitudinally bevelled shape.

This bevelled shape actually performs a self-centering function as the trays are stacked, especially when automatic means are used to stack them.

Preferably the invention may provide one or more of the following features: the tray is made of corrugated cardboard whose channels run parallel to the base of said tray, perpendicular to the overlap, which enhances the rigidity of the tray in the direction of its length; two opposite side walls consist of leaves each joined on either side, along first fold lines, to end wings partially forming the two other walls; each end wing is fixed to the external face of the leaf with the overlap of the adjacent side wall. Such an arrangement reinforces the strength of the handle and makes it possible to brace the side walls as the tray is being formed; 3 the fold lines are inclined outward from the line joining the leaves to the base, in that the upper peripheral base of said leaves include studs at their end and in that the base includes opposite openings designed to interact with said studs; the opposite side walls including the longitudinal flaps forming the overlap each have a central vertical part which is lower than the adjacent side walls; the tray is designed to contain at least one layer, or at least two superposed layers, of containers joined to one another at the top of each of said layers, the respective dimensions of the containers and of the tray being such that the upper layer of containers can support the weight of the tray on top, optionally via an inserted intermediate sheet; the dimensions of the tray are designed to allow the trays to be nested one inside the other over a height of less than or equal to 1/3 of the height of said tray; the respective dimensions between containers and tray are designed such that the lower face of the top part of the lower layer is located above said overlap.

The invention also proposes blanks for the formation of trays as described above.

It thus proposes a blank for making a tray, including a rectangular central panel having a leaf on each side, namely two first rectangular or substantially rectangular opposite leaves and two second rectangular or substantially rectangular opposite leaves, said second opposite leaves each being joined on either side, by first fold lines, to end wings, characterized in that said first leaves each include a longitudinal flap designed to be folded inward with respect to the tray and fixed by adhesive bonding to one face of said corresponding first leaf to form an overlap over part of the height of said leaf, and in that the cardboard has a basis weight of lower than 350 g/m2.

Preferably the cardboard is a corrugated cardboard. In a preferred embodiment, the basis weight of the cardboard is 330 g/m2.

In an advantageous embodiment, said leaves also each have at least one opening allowing grasping by a user, and/or forming a handle, which will be positioned underneath said overlap when this overlap has been formed.

Advantageously, each leaf is joined to the central panel by a strip connected, by parallel fold lines, to said leaf on one side and to the central panel on the other, the side edges of the strip being inclined outward from the central panel. 4 In other words, the first fold lines are joined to the central panel by the free edge of an intermediate strip, said free edge being inclined with respect to the edges of the base of the tray.

Thus, the side edges of the intermediate strips are inclined with respect to the fold lines, over a first part located on the side of the central panel so as to give the base of the tray a partially frustopyramidal section in the transverse and longitudinal directions of the tray, the walls then being once again vertical.

Advantageously the first fold lines are inclined with respect to the edges of the base of the tray and/or the side edges of the first leaves are inclined with respect to the fold lines, so as to give the tray a frustopyramidal section in the transverse and/or longitudinal direction.

In an advantageous embodiment, the smaller base of the first leaves is on the side of the central panel.

Also advantageously, at least part of the periphery of the second leaves and/or the first leaves comprises a protuberance for facilitating nesting and/or forming a stud which can interact with an opening in the base of the tray at the edge and/or a notch on the lower peripheral edge of the end wings.

Preferably the first fold lines are inclined with respect to the edges of the tray, so as to give the tray a frustopyramidal shape whose smaller base is on the side of the central panel.

In a preferred embodiment, the blank is made of corrugated cardboard whose channels run parallel to the leaves having side wings.

Preferably the second leaves are increasingly wider than the first leaves having overlap flaps.

The invention also proposes a packaging item including a tray of the type described above, characterized in that it includes at least one layer of at least two rows of containers joined together at the top of each of said layers, the respective dimensions of the containers and the tray being such that the upper layer of containers can support the weight of the tray above, optionally via an inserted intermediate sheet, for example and advantageously owing to the partial nesting possible between trays.

The invention also proposes a machine for forming a tray from a blank of cardboard having a basis weight of less than or equal to 350 g/m2, including a base panel having side leaves, some of which have end wings, forming the side walls of the tray, characterized in that said machine includes: a plate for bearing on the surface of said base panel, including raised side edges to form a tray of frustopyramidal section in the transverse and longitudinal directions, with a shape complementary to that of the base of the tray to be formed, a mandrel including a pressing part with a shape complementary to that of the bearing plate, means for pressing said mandrel on said bearing plate, means for folding the side leaves and the corresponding wings against the opposite faces of said mandrel, and means for fixing said leaves and wings thus folded to one another and in that, as the tray has two opposite longitudinal side leaves each with end wings and two opposite transverse side leaves each with a longitudinal flap, the machine also has adhesive applicators for depositing lines of adhesive, as a blank is conveyed along, on said transverse leaves and/or longitudinal flaps as well as pressing means for pressing the longitudinal flaps on the adjacent transverse side leaves to form overlaps.

Advantageous embodiments also offer one and/or other of the following arrangements: the mandrel can be retracted between a first position for forming the tray and a second position in which it is separated from the walls of the tray; the retractable mandrel is formed by a frame comprising four edges which are perpendicular or oblique with respect to the pressing face, the edges having bevelled faces; the means for folding the side leaves comprise, at each corner of the tray, a pressing roller designed to push the opposite leaves and wings from a flat position to a position in which the leaves and wings are fixed to one another to form the tray; the pressing means include at least one longitudinal vertical presser designed to press the base panel on a bearing face at a distance from the join line with 6 the corresponding longitudinal or transverse leaf, and means for folding and pressing the longitudinal flap including a pressing device, for example comprising a cylinder, designed to fold down said flap on the adjacent leaf; the pressing means comprise vertically actuatable pressers mounted on 5 block cylinders, allowing flexibility in side adjustment when passing the bevelled base with a vertical movement, before moving on to said vertical walls positioned above.

Brief Description of Drawings The invention will be more clearly understood on reading the following description of 10 embodiments, provided by way of nonlimiting examples.

The description refers to the attached drawings, in which: Figure 1 is a perspective view from above of a tray according to a first embodiment of the invention; Figure 2 is a plan view of a blank corresponding to the tray in figure 1; Figure 2A is a plan view showing a variant of the blank of figure 2 according to the invention; Figure 3 is a perspective view of a layer of trays according to figure 1; Figure 4 is a perspective view from above of a stack of packaging items formed from trays according to figure 1, showing how they nest together and how the weight is borne by the products; Figure 5 is a plan view of a blank corresponding to another embodiment of the invention; Figure 6 is a perspective view from above of a stack of packaging items formed from trays according to the invention corresponding to the blank of figure 5; Figure 7 is a perspective view from above of a tray according to another embodiment of the invention with a bevelled base; Figure 8A is a view in part section, along IIA-IIA, of figure 7; Figure 8B is a view in part section, along IIB-IIB, of figure 7; Figure 9 is a plan view from above of a blank for making the tray according to figure 7; Figures 10 and 11 are plan views of blanks corresponding to two other embodiments of the invention; 7 Figure 12 is a view in part section of the device for pressing the base of the tray, in the retracted position (first half-section) and in the pressing position (second half-section); Figure 13 is a view in part section of the retractable mandrel system according to an embodiment of the invention, in the retracted position (first half-section) and in the pressing position (second half-section); and Figure 14 is a perspective view of the plate for holding the base of the tray on the mandrel according to an embodiment of the invention.

Best Mode for Carrying Out the Invention Figure 1 shows a tray 1 made of double-sided corrugated cardboard between 1 and 2 mm thick, with a basis weight of 330 g/m2, made from three sheets of 100 g/m2 paper.

In other embodiments, three sheets with basis weights of 90 g/m2, or even 80 g/m2 Such lightweight paper was not used for the cardboard in trays of the prior art as it was deemed to be too weak, in particular for the handles and in terms of vertical 20 compression.

The tray 1 has four side walls 2, 3, 4 and 5 and a base 6.

The two opposite side walls 3 and 5 are identical and comprise three parts, namely 25 two rectangular or substantially rectangular trapezoidal wings 7, 8 each integral with, and the same height as, the adjacent side walls 2, 4, and an isosceles trapezoidal leaf 9 joined to the base 6 by a fold line 10. More precisely, the leaf 9 has side edges B inclined outward from the fold lines 10. It comprises a longitudinal flap 11 forming an overlap over part of the height of said leaf, for example a third or half of said height, 30 and all along the length of said leaf. The flap 11 comprises side edges C inclined inward to allow the edges B and C to be superposed when the flap is folded down on the leaf, about the double join line 18, to form the overlap.

Each leaf has a central opening 12, for example of oval shape, of a size allowing the 35 tray to be grasped by one or two fingers or by the hand of a user, this opening being are used. 8 positioned just below the overlap once said overlap has been folded down and bonded to the internal face of the corresponding side wall.

This handle has for example a lower side 13 coinciding with the lower edge 10 where 5 the side wall meets the base.

The two other side walls 2 and 4 are trapezoidal with their smaller base coinciding with the edge of the base.

Each side wall has, in a manner known per se, openings for ventilation of the products stored on pallets, i.e. openings 14, for example oval, in the opposite longitudinal side walls 2, 4 and small round openings 15 in the wings 7 and 8 of the opposite side walls 3, 5.

According to the embodiment of figure 1, the tray has frustopyramidal longitudinal and cross sections so as to allow the whole of the base of the tray to nest at least partially in a lower tray.

In the remainder of the description the same reference numerals will be used to 20 designate identical elements.

Figure 2 is a plan view of the blank 16 for making the tray of figure 1.

The blank 16 comprises a central panel consisting of the rectangular base 6 having on 25 each side a leaf designed to form, at least partially, a side wall, namely two first opposite isosceles trapezoidal leaves 9 and two second opposite isosceles trapezoidal leaves 2 and 4, said second opposite leaves each being joined on either side by first fold lines 17 to the end wings 7, 8.

The wings 7, 8 are designed to be folded inward with respect to the tray and fixed by adhesive bonding to the external face of the corresponding first leaf 9 to form the side walls 3 and 5. The first leaves 9 themselves comprise a longitudinal flap 11 in the shape of an isosceles trapezoid in the reverse direction to the leaf 9, to form an overlap over part of the height of said leaf as described above with reference to 35 figure 1. 9 This flap runs along the whole length of said leaves, ensuring lateral rigidification of the tray, the overlap playing the part of a bracing beam between the two other opposite side walls.

The first leaves 9 are also each equipped with a central orifice, for example of oval shape and with dimensions allowing grasping by the hand of a user, which will form a handle and will be positioned underneath the overlap when this overlap has been formed.

More precisely, the future overlap consists of the horizontal flap 11 joined to said leaf 9, for example by a double fold line 18.

In this embodiment, the first fold lines 17 are inclined with respect to the opposite sides of the tray, which extend out from them, so as to create a frustopyramidal shape in the 15 longitudinal direction of the tray once formed, the smaller base of the wall being on the side of the central panel 6.

Such a blank makes it possible to form a tray of trapezoidal section in the transverse and longitudinal direction.

In the embodiments described more particularly here the channels run parallel (cf. figure 2) to the leaves having side wings.

Figure 2A shows a variant 16' of the blank of figure 2. More precisely, the blank 16' 25 comprises two second leaves 2 and 4 as described above and two first rectangular leaves 9' whose peripheral edge is joined to a rectangular flap 11' designed to form the overlap.

Openings E along and at each end of the fold lines joining the leaves 2 and 4 to the 30 base are provided in order to interact with protuberances T positioned on the external upper periphery of said leaves.

Figure 3 shows trays 1, 1', 1", ... according to the embodiment of the invention of figure 1 arranged horizontally on a pallet (not shown) for handling and transport.

The trays are arranged side by side and may be joined in pairs using an intermediate sheet 19 having central notches 20 and side notches 21 to allow the sheet to engage with the upper side edges 22 of the side walls, the sheet then resting on the products arranged inside the trays, immobilizing the trays and ensuring better distribution of the weights of the packaging items above on the products.

Figure 4 shows how two packaging items, obtained from trays 1 and 1' according to the embodiment of the invention more particularly described here, are stacked.

The packaging items are filled with products whose total height inside each tray is lower than the total height of the side walls of the packaging.

More precisely, each packaging item comprises two layers 23, 24 of two rows of containers 25, for example yoghurt pots, joined to one another at the top 26 of each layer, in a manner known perse.

The respective heightwise dimensions h of the containers and H of the tray are such that the top part 26 of the container of the top layer is at a distance of less than the total height H (2h<H).

Given the frustopyramidal shape of the boxes, the bottom of the walls 27' of the upper tray 1' nests inside the walls 27 of the lower tray 1, in such a way that the base of said upper tray rests on the products 25, for example via a sheet 28, and not on the side walls of the tray 1.

This allows the loads of the upper trays to bear down irrespective of the strength of the cardboard, since it is the products which support the weight of the trays above.

Figure 5 shows another embodiment of a blank 29 for a tray according to the invention. This blank comprises a rectangular central panel 30 joined to two opposite rectangular longitudinal side leaves 31 and 32 each having, on either side, wings joined to said leaves by first fold lines 34, the wings 33 and the leaves 31,32 comprising at the adjacent ends of their external periphery 35, tenons 36 forming a protuberance which is centred on and straddles the ends of the corresponding fold lines 34. 11 For its part, the central panel 30 comprises bracket-shaped notches 37 coinciding with its corners 38, which can interact with the corresponding tenons bordering the sides of the corners of the panel below.

The panel 30 is also joined, along its two other opposite sides, by fold lines 39 aligned with the first fold lines 34 in such a way that the section of the packaging item is rectangular, to end leaves 9 identical to those of figure 2, each comprising a longitudinal flap 11 for forming an overlap and an opening 12 for grasping by a user.

Figure 6 shows a stack of packaging items 40, 40' obtained from blanks 29 as described with reference to figure 5.

The walls 41 of the tray of the upper packaging item 40 rest on the walls 41' of the lower packaging item 40', with a good join and vertical continuity of the walls, most of 15 the weight of the upper packaging item being borne by the products 42 themselves, which are dimensioned in such a way that the base of the upper tray, optionally via an inserted intermediate sheet 43 having a certain thickness, rests on the top of the products of the lower tray.

The engagement of the tenons 36 in the openings 37 prevents two trays from sliding with respect to one another in the longitudinal direction.

A description will now be given of the formation of a stack of packaging items 1,1' with reference to figures 2 and 4.

Starting with the blanks 16, and in a manner known per se, for example using a conventional tray-forming machine of the prior art, trays 1,1' are formed. To this end, after the flaps 11 have been bonded to the internal face of the leaf 9, to form the overlaps, the wings 7 and 8 are bonded to the external faces of the adjacent leaves 9 30 to form the side walls for grasping the trays, which are thus configured to present a trapezoidal section.

The trays are then filled with products 25 in a manner known per se. A sheet is then placed on the top face of the products before another tray is nested on top. 12 The angle of the bases of the trapezoid is for example around 95° or even 98°, relatively obtuse to allow good nesting while being close to a right angle to obtain a compact, vertical stack.

Figure 7 shows a tray 51 made of double-sided corrugated cardboard between 1 and 3.5 mm thick, with a basis weight of 330 g/m2, made from three sheets of 100 g/m2 paper.

In other embodiments, three sheets with basis weights of 90 g/m2, or even 80 g/m2 are used.

Such lightweight paper was not used for the cardboard in trays of the prior art as it was deemed to be too weak, in particular for the handles and in terms of vertical compression.

The tray 51 has four side walls 52, 53, 54 and 55 and a base 56.

The two opposite side walls 53 and 55 are identical and comprise three parts, namely two rectangular wings 57, 58 each integral with, and the same height as, the adjacent side walls 52, 54, and a rectangular leaf 59 joined to the base 6 by an intermediate strip 110. More precisely, the intermediate strip 110 has side edges 111 inclined outward from the fold lines 112 with the base, and have an inclined shape forming an angle of between 5° and 45°, for example 10°, with the vertical.

In another embodiment, the wings 57 and 58 may for example have the shape of an L, for example an upside-down L, whose main leg is positioned on the side of the corresponding adjacent leaf 52 or 54, providing in particular better guidance for the flat blank into the plane of formation.

The leaf 59 moreover comprises a longitudinal flap 112 forming an overlap over part of the height of said leaf, for example a third or half of said height. The flap 113 is folded down on the leaf to form the overlap about the double join line 114 all along the length of the leaf.

Each leaf has a central opening 115, for example of oval shape, of a size allowing the tray to be grasped by the hand of a user, this opening being positioned just below the 13 overlap once said overlap has been folded down and bonded to the internal face of the corresponding side wall.

This handle has for example a lower side coinciding with the lower edge forming a fold line 116 where the side wall meets the base.

The two other side walls 52 and 54 comprise an inclined strip 117 joining them to the edge of the base, like the intermediate strips 110.

Each side wall has, in a manner known per se, openings for ventilation of the products stored on pallets, i.e. openings 118, for example oval, in the opposite longitudinal side walls 52, 54 and small round openings 119 in the wings 57 and 8 of the opposite side walls 53, 55.

According to the embodiment of figure 7, the lower part of the walls of the tray has frustopyramidal longitudinal and cross sections so as to allow the whole of the base of the tray to nest at least partially in a lower tray.

In the remainder of the description the same reference numerals will be used to designate identical elements.

Figures 8A and 8B show, in part section, the bevelled faces or strips 110 and 117 forming the lower parts of the walls with an angle of between 45° and 89°, for example of 80° or 85°, with the horizontal.

Figure 9 is a plan view of the blank 120 for making the tray of figure 7.

The blank 120 comprises a central panel consisting of the rectangular base 56 having on each side a leaf designed to form, at least partially, a side wall, namely two first opposite rectangular leaves 59 and two second opposite rectangular leaves 52 and 54, said second opposite leaves each being joined on either side by first fold lines 121 to the end wings 57, 58.

The wings 57, 58 are designed to be folded inward with respect to the tray and fixed by adhesive bonding to the external face of the corresponding first leaf 59 to form the side walls 53 and 55. The first leaves 59 themselves comprise a rectangular 14 longitudinal flap 113 able to form an overlap over part of the height of said leaf as described above with reference to figure 7.

The first leaves 59 are also each equipped with a central orifice 115, for example of oval shape and with dimensions allowing grasping by a hand of a user, which will form a handle and will be positioned underneath the overlap when this overlap has been formed.

More precisely, the future overlap consists of the horizontal flap 113 joined to said leaf 59, for example by a double fold line 114, said leaf 59 being joined to the panel by the strip 110 which has, on either side, parallel fold lines 116, 116' joining it to the tray 56 on one side and to the rest of the leaf 59 on the other.

The opening 115 thus runs right across the bevelled strip 10 whose side edges are inclined outward and extended by the peripheral free edges of the corresponding leaf 59.

In this embodiment, the first fold lines 121 are straight, then replaced by free edges 122 which are inclined with respect to the opposite sides of the tray, which extend out from them, so as to give the lower part of the wall a frustopyramidal shape in the longitudinal direction of the tray once formed, the smaller base of the wall being joined to the central panel 56 by a fold line 123 and forming a bevelled face between said fold line 123 and a parallel fold line 124 joined to the rest of the corresponding leaf 52 or 54.

Such a blank can be used to form a tray having a base with a trapezoidal section in the transverse and longitudinal direction.

In the embodiments described more particularly here, the channels run parallel to the leaves having side wings.

Figure 10 shows a variant 130 of the blank of figure 9 for making a tray in which the height of the transverse walls 131 is the same as those of the longitudinal walls 132.

The ventilation orifices 133 in this case run right across the longitudinal strips 134 and 135 forming the frustopyramidal base in both directions of the tray.

Figure 11 shows another variant of the blank 130' of figure 9 comprising three openings on the bevelled face 110, namely a first central opening 115' into which the user can insert two fingers, and two openings 115", for example circular, also allowing grasping by one finger of the user who therefore can choose how to take hold of the tray.

In this case, the internal peripheries of the wings 58 on the side of the leaf 52 themselves have notches 115'" which are complementary in shape to those of the openings 115".

Figures 12, 13 and 14 show a plate 140 of the mandrel machine according to the embodiment of the invention described more particularly here, for forming the tray of figure 7.

The means for conveying the blank 141 horizontally between the mandrel 142 and the plate 140 are known per se and will not be described below.

Moreover, and without it being necessary to refer to a particular figure, the blank to be formed into a tray is first prepared by adhesively bonding the overlaps. To this end, as the tray has two opposite longitudinal side leaves 52, 54 each with end wings 57 and 58, and two opposite transverse side leaves 59 each with a longitudinal flap 113, the machine also has adhesive applicators for depositing lines of adhesive, as a blank is conveyed along, on said transverse leaves and/or longitudinal flaps as well as pressing means for pressing the longitudinal flaps on the adjacent transverse side leaves to form overlaps.

The pressing means comprise for example at least one longitudinal vertical presser designed to press the base panel on the bearing face at a distance from the join line with the corresponding transverse leaf, and means for folding and pressing the longitudinal flap comprising a pressing cylinder designed to fold down said flap on the adjacent leaf.

Once the blank is positioned for example over the bearing plate 140 which has frustopyramidal longitudinal and cross sections (cf. figure 14), said plate is moved upward to form the base of the packaging item (cf. figure 12) via pushing means 143 16 integral with the plate and pressing arms 144 having at their end a roller 146 for pressing on the walls 145 of the mandrel.

More precisely, the pressing arms 144 are designed to move vertically between a retracted position 147 and a pressing position 148, openings 149 (cf. figure 14) being provided in the bevelled faces 150 of the tray to allow said arms with their rollers to pass through, the two other inclined side edges 151 of the plate being uninterrupted, for example.

Advantageously (cf. figure 13), the mandrel 142 can be retracted in both the longitudinal and transverse directions, using rams 152 which are integral with internal counterpressure plates 153, to form the packaging item from the blank 141.

Means 154 for applying pressure externally, for example with rams, are actuated simultaneously to shape the walls of the tray above the plate, and ensure definitive bonding by pressing, in a manner known per se, adhesive having been previously applied to the elements by means provided, also known per se.

After the packaging items have been formed, they are filled with products whose total height inside each tray is lower than the total height of the side walls of the packaging.

For example, each packaging item comprises two layers of two rows of containers, for example yoghurt pots, joined to one another at the top of each layer, in a manner known per se.

The respective heightwise dimensions h of the containers and H of the tray are such that the top part of the container of the top layer is at a distance of less than the total height H (2h<H).

Given the frustopyramidal shape of the boxes at their bottom, the bottom of the walls of the upper tray nests inside the walls of the lower tray, in such a way that the base of said upper tray rests on the products, for example via a sheet, and not on the side walls of the tray 1.

This allows the loads of the upper trays to bear down irrespective of the strength of the cardboard, since it is the products which support the weight of the trays above. 17

Claims

As goes without saying and is also obvious from the above, the present invention is not limited to the embodiments described more particularly. On the contrary, it encompasses all variants thereof, especially those in which the packaging item 5 comprises more than two layers of superposed products and/or those in which the overlap is made toward the outside of the leaf in question and not toward the inside, and/or that in which the wings are adhesively bonded to the inside of said leaf with the overlap. 18 CLAIMS

1. A tray made of a sheet of cardboard including four side walls and a base, characterized in that two opposite side walls each include a leaf having a 5 longitudinal flap designed to form an overlap over part of the height of said leaf and in that the basis weight of the cardboard is less than or equal to 350 g/m2.

2. The tray as claimed in claim 1, characterized in that said opposite side walls each have at least one opening allowing grasping by a user, positioned 10 underneath said overlap.

3. The tray as claimed in either one of claims 1 and 2, characterized in that the tray has a frustopyramidal longitudinal and/or cross section allowing said tray to nest at least partially in a lower tray. 15

4. The tray as claimed in either one of claims 1 and 2, characterized in that the lower part of each of the side walls forms a bevelled face inclined toward the vertical part of the tray allowing said tray to nest at least partially in a lower tray. 20

5. The tray as claimed in any one of the preceding claims, characterized in that it is made of corrugated cardboard whose channels run parallel to the base of said tray, perpendicular to the overlap.

6. The tray as claimed in any one of the preceding claims, characterized in that 25 two opposite side walls consist of leaves each joined on either side, along first fold lines, to end wings partially forming the two other side walls.

7. The tray as claimed in claim 6, characterized in that each end wing is fixed to the external face of the leaf with the overlap of the adjacent side wall. 30

8. The tray as claimed in either one of claims 6 and 7, characterized in that the fold lines are inclined outward from the line joining the leaves to the base, in that the upper peripheral base of said leaves include studs at their end and in that the base includes opposite openings designed to interact with said studs. 35 19

9. The tray as claimed in any one of the preceding claims, characterized in that the opposite side walls including the longitudinal flaps forming the overlap each have a central vertical part which is lower than the adjacent side walls.

10. The tray as claimed in any one of the preceding claims, characterized in that it is designed to contain at least one layer of containers joined to one another at the top, the respective dimensions of the containers and of the tray being such that the upper layer of containers can support the weight of the tray on top.

11. The tray as claimed in claim 10, characterized in that its dimensions are designed to allow the trays to be nested one inside the other over a height of less than or equal to 1/3 of the height of said tray.

12. The tray as claimed in any one of the preceding claims for storing layers of containers, characterized in that the respective dimensions between containers and tray are designed such that the lower face of the top part of the lower layer is located above said overlap.

13. A blank for making a tray, including a rectangular central panel having a leaf on each side, namely two first rectangular or substantially rectangular opposite leaves and two second rectangular or substantially rectangular opposite leaves, said second opposite leaves each being joined on either side, by first fold lines, to end wings, characterized in that said first leaves each include a longitudinal flap designed to be folded inward with respect to the tray and fixed by adhesive bonding to one face of said corresponding first leaf to form an overlap over part of the height of said leaf, and in that the basis weight of the cardboard is less than or equal to 350 g/m2.

14. The blank as claimed in claim 13, characterized in that said leaves also each have at least one opening forming a handle, which will be positioned underneath said overlap when this overlap has been formed.

15. The blank as claimed in claim 14, characterized in that each leaf is joined to the central panel by a strip connected, by parallel fold lines, to said leaf on one side and to the central panel on the other, the side edges of the strip being inclined outward from the central panel.

16. The blank as claimed in claim 15, characterized in that the first fold lines are inclined with respect to the edges of the tray, so as to give the tray a frustopyramidal shape whose smaller base is on the side of the central panel. 5

17. The blank as claimed in any one of claims 14 and 15, characterized in that it is made of corrugated cardboard whose channels run parallel to the leaves having side wings.

18. The blank as claimed in any one of claims 15 to 17, characterized in that the 10 second leaves are increasingly wider than the first leaves having overlap flaps.

19. A packaging item including a tray as claimed in any one of claims 1 to 12, characterized in that it includes at least one layer of at least two rows of containers joined together at the top of each of said layers, the respective 15 dimensions of the containers and the tray being such that the upper layer of containers can support the weight of the tray above.

20. A packaging item as claimed in claim 19, characterized in that an intermediate sheet is inserted between at least one said layer of containers and the tray 20 above.

21. A tray made of a sheet of cardboard, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings. 25

22. A blank for making a tray, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings. 21