EP0978371A1 - Method of reinforcing the load carrying sidewalls of trays of corrugated cardboard and tray so obtained - Google Patents

Abstract

The procedure consists of making a straight cut (28) through the layers (14, 16) of the side wall flap, leaving only the outer layer (18) uncut. When the side wall is folded upwards relative to the base (22) of the tray along fold line (26) its upper section (32) above the cut is folded over outwards and glued to give a wall of double thickness with the corrugated cardboard channels running vertically through it. The position of the cut (28) is selected so that the free edge (27) of the outer section lies flush with the underside (40) of the tray base when folded.

Description

FIELD OF THE INVENTION

The present invention relates to a method of reinforcement of the stacking resistance of the walls carrying a corrugated packaging and a conditioning obtained by this process.

PRIOR STATE OF THE ART

It is known to strengthen the stacking resistance of load-bearing walls of a corrugated cardboard packaging in folding or folding inward packaging of the flaps which are hinged on the edge upper load-bearing walls by double lines of repression. These flaps which have a width substantially equal to the height of the walls, are applied on the inner wall of the latter and their free edge lower wedges against the bottom wall of the conditioning. The thickness of the walls is thus doubled over the entire height.

To give maximum resistance to compression at the transverse walls, the flutes of the corrugated cardboard must be oriented vertically in the walls side and in the flaps and therefore the double discharge lines must be oriented in a direction perpendicular to the cardboard grooves. These double delivery lines are made by marking on the cardboard blank from which the packaging comes, two very close parallel fold lines. In the packaging in the assembled state, the narrow strip defined between the two fold lines is in principle straight and contained in a horizontal plane.

However, experience shows that, most of the time, this strip has an irregular profile, due to the fact that poorly controlled crushing of corrugated cardboard flutes on the discharge lines. We see that this band is often curled or has a certain degree of warping. It follows that when several packaging is stacked, the compression force may to exercise only on certain discrete points of the edge upper side walls. At these points, the side walls may buckle or show some fatigue which reduces its resistance to stacking.

Another disadvantage of the overhang of the walls sideways inwards lies in the fact that the contact between the lower edge of the flaps and the wall of the bottom is relatively elastic due to the presence in the back wall of the cardboard grooves. So when stacking, the side walls may undergo a slight deformation due to crushing of the grooves in the wall of the background.

SUMMARY OF THE INVENTION

à pratiquer sur ledit volet, sensiblement à égale distance entre son bord libre et ladite ligne de pliage, une coupe rectiligne à mi-chair qui tranche toute l'épaisseur du carton sauf la feuille de couverture se trouvant sur la face extérieure du flan, ladite coupe définissant de part et d'autre, une paroi latérale articulée sur la paroi de fond par ladite ligne de pliage et un rabat articulé sur ladite paroi latérale par une ligne de liaison formée sur la feuille de couverture non tranchée ;

à dresser le volet perpendiculairement à la paroi de fond ;

à plier le rabat vers l'extérieur du conditionnement en le faisant pivoter autour de ladite ligne de liaison ;

et à coller le rabat sur la face extérieure de la paroi latérale.

The present invention aims to remedy these drawbacks and first of all proposes a method for reinforcing the load-bearing walls of a package produced from a corrugated cardboard blank with at least one corrugated layer, in which each of the load-bearing walls is made up by a flap articulated on the bottom wall of the packaging by a fold line, said method being characterized in that it consists:

to make on said flap, substantially at an equal distance between its free edge and said fold line, a straight cut with half-flesh which cuts the entire thickness of the cardboard except the cover sheet located on the outer face of the blank, said section defining on either side, a side wall articulated on the bottom wall by said fold line and a flap articulated on said side wall by a connecting line formed on the sheet of cover not cut;

erecting the flap perpendicular to the bottom wall;

folding the flap outwards of the packaging by pivoting it around said connecting line;

and gluing the flap to the outside of the side wall.

This gives the top of the side wall and flap adjoining a perfectly flat support surface and horizontal, of width equal to twice the thickness of the cardboard. This surface provides stable and regular support for another conditioning.

The flap has a height exactly equal to that of the side wall, so that its bottom edge reaches the same level as the underside of the bottom wall. he as a result that when several packages are stacked, the side wall and the flap of each are supported on the side wall and the flap of the underlying packaging.

The compression force is therefore equally distributed between the side wall and the flap and is exerted uniformly on the entire length of these.

The invention also relates to a packaging obtained by the method described above.

DESCRIPTION OF A PREFERRED EMBODIMENT

la figure 1 montre une vue partielle d'un flan en carton ondulé montrant notamment une paroi latérale et son rabat avec une coupe à mi-chair entre eux ;

la figure 2 est une vue à plus grande échelle en coupe suivant la ligne II-II de la figure 1 ;

la figure 3 est une vue en coupe partielle illustrant le mode de pliage du flan pour former la paroi latérale rembordée extérieurement par le rabat ;

la figure 4 représente un mode de réalisation particulier d'un flan servant à réaliser un conditionnement pourvu de parois latérales porteuses renforcées par le procédé illustré par les figures 1 à 3 ; et

la figure 5 montre le conditionnement réalisé avec le flan de la figure 4.

An embodiment of the invention will now be described with reference to the appended drawing in which:

Figure 1 shows a partial view of a corrugated cardboard blank showing in particular a side wall and its flap with a half-cut section between them;

Figure 2 is an enlarged sectional view along line II-II of Figure 1;

Figure 3 is a partial sectional view illustrating the method of folding the blank to form the side wall folded outwardly by the flap;

FIG. 4 represents a particular embodiment of a blank used for producing a packaging provided with load-bearing side walls reinforced by the method illustrated by FIGS. 1 to 3; and

FIG. 5 shows the packaging produced with the blank of FIG. 4.

DETAILED DESCRIPTION OF AN EMBODIMENT

We will first explain the principle of the reinforcement according to the invention with reference to Figures 1 to 3 which represent a portion of blank in corrugated cardboard comprising two fluted layers 10, 12 separated by a sheet of intermediate paper 14 and covered externally by two interior cover sheets 16 and exterior 18, but as will be seen, the invention also applies to corrugated cardboard comprising one, two or more fluted layers.

The blank portion 20 comprises a bottom wall 22 on which a flap 24 is articulated by a fold line 26. The fold line is formed on the face of the blank intended to be inside the packaging, and which is the visible side in FIG. 1. The shutter has a width L which is twice the height h of the box that we want to make. About halfway between the fold line 26 and the edge 27 of the flap 24, a half-cut 28 is made which cuts the cardboard over its entire thickness with the exception of the outer cover sheet 18. The section 28 defines on the shutter a side wall 30 articulated to the bottom wall 22 by the fold line 26 and a flap 32 which is attached to the side wall only by the line 34 not cut from the outer cover sheet 18.

The fold line 26 and the cut 28 are perpendicular to the direction of the grooves 35.

Figure 3 shows how the blank is folded: the flap 24 to bring it into position perpendicular to the bottom wall 22, by folding around the fold line 26, then fold the flap 32 outward around the connecting line 34. The flap is then glued to the face exterior of the side wall.

Because the section 28 is straight, we obtain at the upper part of the side wall and the flap a very regular, flat and horizontal cutting surface 36 on its entire length. In addition, the lower edge 27 of the flap is is at exactly the same level as that of the face lower 40 of the bottom wall. It results from these two characteristics only if several packages are stacked, the compressive force is distributed equally over the side wall and the flap of each package and evenly along the length of these elements. The packaging therefore has good compressive strength higher than that of wrapped packaging internally.

We will now describe in detail with reference to Figures 4 and 5, an example of packaging, here a tray for Brie cheese.

Figure 4 shows the blank 50 from which is made the set. This blank is substantially rectangular and comprises a central bottom wall 52 of square shape or rectangular, two longitudinal walls 54, 56 articulated by fold lines 58, 60 along two sides parallels of the bottom wall and two flaps 62, 64 articulated by fold lines 66, 68 along the two other sides of the bottom wall. The flaps 62, 64 have a width greater than or equal to twice that of the walls longitudinal 54, 56.

Four rectilinear slots 70, 72 and 74, 76 are formed from the two longitudinal edges of the blank, in alignment with the fold lines 66, 68 and over a distance d substantially equal to twice the width l of the longitudinal walls.

The flaps 62, 64 are shared by half-cut sections 78, 80, in strips 82, 84 and 86, 88 of equal width l .

The blank having a central symmetry, we will only describe the left side.

The strips 82, 84 are separated at their ends by incisions 90, 92, the same length as the slots 70, 72. One thus defines at the ends of the bands, legs independent 94, 96 and 98, 100. The inner legs 94, 98, i.e. those associated with the band interior 82, can be folded along lines of folding 102, 104 passing through the ends of the slots 70, 72.

On the outer legs 96, 100 are marked with fold lines 106, 108 aligned with fold lines longitudinal 58, 60. These fold lines define at ends of legs, external fixing tabs 110, 112.

On the inner legs 94, 98 are marked with fold lines 114, 116 parallel to fold lines 102, 104 and which define, on both sides, corner elements 118, 120 and fixing tabs internal 122, 124.

U-shaped incisions are made on the band outer 84, from the half-cut section 78, from so as to release centering pins 126, 128. recesses 130, 132 of shape complementary to that of pins are drilled in the inner band 82, along the transverse fold line 66. These recesses are intended to receive the pins of a packaging inferior.

The packaging tray is shaped as follows: we start by erecting the flaps 62, 64 perpendicular to the bottom wall 52 by folding around fold lines 66, 68, then fold the strips 84, 88 outwards, by folding around the half-cuts 78, 80 to apply against the face exterior of interior strips 82, 86. The strips outside are glued on the inside strips.

Then fold inward the inner tabs 94, 98 around the fold lines 102, 114; 104, 116, then the longitudinal walls 54, 56 are erected perpendicular to the bottom wall 52 by folding around fold lines 58, 60.

Then glue the inner tabs 122, 124 on the inner face of the longitudinal walls 54, 56 in ensuring that the corner elements 118, 120 are placed diagonally in the corners of the bottom wall 52. Finally, we fold the outer tabs 110, 112 and glue them on the outer face of the longitudinal walls 54, 56.

This gives the plate shown in Figure 5. This tray is particularly resistant because it has two transverse load-bearing walls each formed of two cardboard thicknesses and also because the ends longitudinal walls are sandwiched between the interior tabs and exterior tabs.

Claims (6)

Method for reinforcing the load-bearing walls of a package produced from a corrugated cardboard blank (20) with at least one fluted layer (10, 12), in which each of the load-bearing walls is constituted by an articulated flap (24) on the bottom wall (22) of the packaging by a folding line (26), said method being characterized in that it consists: to perform on the inside face of the flap (24), substantially at an equal distance between its free edge (27) and said fold line, a rectilinear half-flesh cut (28) which cuts the entire thickness of the carton except the sheet cover (18) located on the outer face of the blank, said section defining on either side, a side wall (30) articulated on the bottom wall (22) by said fold line (26) and a flap (32) articulated on the side wall by a connecting line (34) formed on said outer cover sheet (18); erecting the flap (24) perpendicular to the bottom wall (22); folding the flap (32) towards the outside of the packaging by pivoting it around said connecting line (34); and gluing the flap to the outside of the side wall. Packaging made from a cardboard blank corrugated (20) with at least one grooved layer (10, 12) and comprising a bottom wall (22) and at least one flap (24) articulated on the bottom wall by a fold line (26), characterized in that said flap (24) comprises, on the face interior, substantially equidistant from its edge free (27) and the fold line (26), a straight cut half-flesh (28) which cuts the entire thickness of the cardboard except the cover sheet (18) located on the face outside of the blank. Packaging according to claim 2, characterized in that the lower edge (17) of the flap reaches the same level than the underside (40) of the bottom wall. Packaging according to claim 2, produced with corrugated cardboard that includes one or more layers grooved (10, 12) interconnected by at least one sheet of intermediate paper (14) and covered on their outer faces by cover sheets (16, 18), characterized in that the half-cut is made through the inner cover sheet (16), the or the fluted layers (10, 12) and the sheet or sheets intermediaries, but not on the cover sheet exterior (18). Packaging according to one of claims 2 to 4, characterized in that it comprises a bottom wall (52) and two longitudinal side walls (54, 56) and two walls lateral transverse (82, 86), articulated on the wall of bottom with fold lines (58, 60, 66, 68), each said transverse side walls (82, 86) being lined by a flap (84) which is articulated thereon by a half-cut (78), said transverse wall (82) and said flap (84) being provided at their ends with tongues (122, 124 and 110, 112) foldable along lines fold (114, 116) perpendicular to the fold line (66) of said transverse wall (82) on the bottom wall (52), the tongues (122, 124) which are adjacent to said transverse wall (82) being glued to the inner face two adjacent longitudinal side walls (54, 56) to said transverse wall (82), while the tabs (110, 112) which are adjacent to the flap (84) are glued on the outer face of said longitudinal walls (54, 56). Packaging according to claim 5, characterized in that said transverse wall (82) is extended by interior corner elements (118, 120) which are placed in diagonal in the corners of the packaging defined between said side wall and said longitudinal walls (54, 56), said corner elements in turn extending by tabs (122, 124) which are glued to the face interior of said longitudinal walls (54, 56).

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