EP0109875B1 - Method and apparatus for shaping cardboard packaging trays, and tray so produced - Google Patents

Abstract

1. Packing tray of corrugated cardboard, of the type comprising a base 12, two longitudinal walls 14, two transversal walls 16 higher than the transversal walls and each terminating at its ends in two angular returns 18, two horizontal entablatures 20 advancing parallel to the base from horizontal upper edges of the transversal walls, and two independent reinforcement sheets 24 applied against the transversal walls and designed to increase the resistance to "bundling" of the ends of the tray or the heads 28 which are defined between the base and the entablatures, the said tray being characterized by the fact that the reinforcement sheets 24 are held in position by reason of the fact that their horizontal edges fit into grooves 34 approximately equal in thickness to the reinforcement sheets and formed by compressing the cardboard along folding lines by which the lateral walls 14, 16, are articulated to the base and to the entablatures, the said reinforcement sheets having for this purpose a height 1 substantially equal to the internal height, h, of the transversal walls 16 puls the sum of the depths of the two grooves 34 into which each of them is fitted.

Description

The present invention relates to improvements made to corrugated cardboard packaging trays, for the packaging and display for sale of fresh products, such as fruit and vegetables, of the type comprising a bottom, two longitudinal walls, two transverse walls of height greater than that of the longitudinal walls and two horizontal entablatures advancing parallel above the bottom from the upper edge of the transverse walls. These entablatures are therefore raised relative to the longitudinal walls and thus allow stacking of the trays without deterioration of the products they contain, as well as good ventilation of said products.

In the following description, each of the terminal portions of the plate which comprise the entablatures will be designated by head.

When transporting and exposing the trays filled with products and stacked in piles, the tray heads are subjected to compression forces. Beyond a certain threshold, which of course depends on the position of the tray in the stack, the density of the packaged products as well as their degree of humidity, the transverse walls of the trays may buckle or soften in losing their resistance. In addition, during their transport from the places of production to the points of sale, the stack of trays work under the action of repeated and sudden shocks, which contributes to further weaken the resistance of the heads of the trays.

By patent FR-A-2 043 948, there is known a packaging tray of the type set out in the preamble of claim 1, said tray comprising a bottom, two longitudinal walls, two transverse walls of height greater than that of the longitudinal walls. and which each end at its ends with two angle returns, two horizontal entablatures advancing parallel to the bottom from the horizontal upper edges of the transverse walls, and two independent reinforcing plates applied against the transverse walls and intended to reinforce the resistance to stacking of the ends of the tray or heads which are defined between the bottom and the entablatures.

The reinforcement plates, which are generally made of corrugated cardboard, are cut with the same surface as that of the internal faces of the transverse walls and are glued or stapled against the latter. Thus doubled, the transverse walls should have better resistance to stacking, but in reality there is practically no improvement in resistance. Indeed, up to a given compression force, only the transverse walls of the tray participate in the resistance to stacking, since the plates have a height less than the external height of the transverse walls. This force being generally greater than the buckling force of the transverse walls, it follows that when the plates intervene, the transverse walls are already deformed. At this time, the weight of the stack plates is no longer supported except by the reinforcement plates which generally do not have the necessary resistance and in turn end up flaming. Thus, instead of adding their resistance to give the tray double resistance to stacking, the transverse walls of the tray and the reinforcement plates intervene at different times. As a result, with such a method, the plate is practically not reinforced. In addition, in such a tray, the cottage or stapling of the reinforcement plates with transverse walls introduces a delay in the manufacturing cycle of the tray.

The present invention overcomes these drawbacks and relates to this end, a packaging tray according to the preamble of claim 1 and which is characterized in that the reinforcing plates are held in place by the fact that their horizontal edges are fitted in grooves of thickness substantially equal to that of the plates and which are formed by crushing the cardboard along the fold lines by which the side walls are articulated on the bottom and on the entablatures, said reinforcement plates having for this purpose a height substantially equal to the internal height of the transverse walls increased by the sum of the depths of the two grooves in which each of them fits.

• à poser à plat à l'état développé le flan sur lequel ont été préalablement formées, par écrasement du carton tout le long des lignes de pliage par lesquelles les parois latérales s'articulent sur le fond et sur les entablements, des rainures d'épaisseur sensiblement égale à celle des plaquettes de renforcement.
• à emboîter les bords horizontaux inférieurs des plaquettes de renforcement dans les rainures formées entre le fond et les parois transversales et à dresser lesdites plaquettes perpendiculairement au fond, et
• à plier successivement autour des plaquettes ainsi positionnées, les parois transversales, les entablements et les retours d'angle pour les amener à leur position normale, chacune des plaquettes se trouvant de ce fait retenue tout le long de ses bords horizontaux entre la paroi transversale adjacente et les flancs des deux rainures dans lesquelles elle est emboîtée.

The invention also relates to a process for shaping the aforementioned packaging tray, which is characterized in that it consists:

• to lay flat in the developed state the blank on which were previously formed, by crushing the cardboard along the fold lines by which the side walls are articulated on the bottom and on the entablatures, thick grooves substantially equal to that of the reinforcement plates.
• fitting the lower horizontal edges of the reinforcement plates into the grooves formed between the bottom and the transverse walls and erecting said plates perpendicular to the bottom, and
• to fold successively around the plates thus positioned, the transverse walls, the entablatures and the angle returns to bring them to their normal position, each of the plates therefore being retained along its horizontal edges between the adjacent transverse wall and the sides of the two grooves in which it is fitted.

• à dresser perpendiculairement, le long des lignes de pliage des parois transversales sur le fond, les plaquettes de renforcement et
• à plier successivement autour des plaquettes, les parois transversales, les entablements et les retours d'angle pour les amener à leur position normale, chacune des plaquettes se trouvant alors pincée, tout le long de ses bords longitudinaux entre les flancs rentrants qui se forment naturellement sur les lignes de pliage des parois adjacentes.

In a variant applied to the case where the blank has no grooves, the method according to the invention consists:

• to be drawn perpendicularly, along the fold lines of the transverse walls on the bottom, the reinforcement plates and
• to fold successively around the plates, the transverse walls, the entablatures and the angle returns to bring them to their normal position, each of the plates then being pinched, all along its longitudinal edges between the re-entrant flanks which form naturally on the fold lines of the adjacent walls.

The advantages of this method reside in the fact that the plates are put in place during the very operation of the volume setting of the plate and that they hold in place of themselves, without it being necessary to staple them or stick them on the transverse walls of the tray. In addition, since they have a height exactly equal to the external height of the transverse walls, reduced by two crushed thicknesses of cardboard, its resistance to stacking is added, at any time, directly to that of the transverse walls.

The present invention also relates to a machine for implementing this method. The machine described in French patent application No. 79 02 484 is used for this purpose, to which some modifications are made to adapt it to the volume setting of trays with reinforced heads.

First of all, it is recalled that this machine comprises a movable assembly consisting of two horizontal and parallel punches of section equal to the internal section of the heads and which are articulated, by means of connecting rods arranged in the form of articulated parallelograms, on a base which is driven by a reciprocating linear movement between an upper position for which the punches are in contact with the cardboard plate to be shaped and a lower position for which the punches are released from the plate.

It follows from this arrangement that when no obstacle is present in their path, the punches move in block with the base and that, otherwise, while the base continues its vertical movement, the punches move horizontally by moving away or getting closer to each other depending on the position of the obstacle.

The improvement according to the invention lies in the fact that in the lower position of the assembly, the punch and rod assembly is in the collapsed position, the external vertical faces of the punches then being respectively situated exactly under the grooves separating the two transverse walls. and the bottom of the cardboard blank, and respectively touching the outlet openings of two fixed stores supplying reinforcement plates, and that said external vertical faces are provided with gripping means capable of gripping the first plate of each store in view to position it under the groove separating the corresponding transverse wall and the bottom of the blank and not to release it only when the heads of the plate have been shaped.

The gripping means can for example be constituted by a vacuum source which sucks the wafers through openings formed on said external faces of the punches.

So that the punches are positioned exactly opposite the store openings, suitable centering means can be provided. In a particular embodiment, the latter comprise at least one patch attached to said external faces of the punches and which, when the punches are correctly centered, comes to fit into a recess of complementary shape formed on the plates.

The boards can be made of any rigid or semi-rigid material, for example corrugated cardboard, flat cardboard, chipboard, plywood, molded plastic, hardboard, etc.

They can have extremely varied forms. In their simplest embodiment, they have a rectangular shape with dimensions greater than those of the transverse walls of the tray, possibly with cutouts on their edges corresponding to the cutouts existing on the heads of the tray. They can also be extended in the longitudinal direction by two lateral flaps intended to be applied against the longitudinal walls of the plate. Such a double dihedral shaped plate provides increased reinforcement of the plate in the corners of the heads.

• La figure 1 est une vue en perspective d'un plateau d'emballage à têtes équipé de plaquettes de renforcement ;
• La figure 2 est une vue en plan d'une plaque servant à la réalisation du plateau selon l'invention ;
• La figure 3 montre une vue en coupe, à échelle agrandie, selon la figure III-III de la figure 1 ;
• La figure 4 est une vue en coupe partielle d'une variante de réalisation du plateau d'emballage ;
• Les figures 5 à 7 montrent trois formes possibles de plaquettes de renforcement ;
• Les figures 8 à 10 représentent en coupe une machine de mise en forme du plateau, dans trois phases successives de son fonctionnement ; et
• la figure 11 représente une vue en perspective partielle de la machine selon l'invention.

Other characteristics and advantages will appear in the description which follows of various embodiments of the wafers according to the invention and of a machine for the installation of these wafers. In this description, reference will be made to the appended drawings in which:

• FIG. 1 is a perspective view of a packaging tray with heads fitted with reinforcement plates;
• Figure 2 is a plan view of a plate for making the tray according to the invention;
• Figure 3 shows a sectional view, on an enlarged scale, according to Figure III-III of Figure 1;
• Figure 4 is a partial sectional view of an alternative embodiment of the packaging plate;
• Figures 5 to 7 show three possible forms of reinforcement plates;
• Figures 8 to 10 show in section a machine for shaping the plate, in three successive phases of its operation; and
• Figure 11 shows a partial perspective view of the machine according to the invention.

We will first refer to Figure 1 which shows a fruit tray 10, said heads.

This tray comprises a rectangular bottom 12. two longitudinal walls 14, two transverse walls 16 terminated at each end by angle returns 18 which are made integral with the inner face of the longitudinal walls 14 by gluing or stapling, and two raised entablatures 20 , contiguous to the transverse walls and forming a projection above the bottom and parallel lie to this one. The entablatures end at their ends by flaps 22 which are applied to the corner returns 18 and are joined thereto, for example by gluing.

To improve the stacking resistance of such a tray, rectangular reinforcing plates 24 similar to that shown in FIG. 5 are used.

As explained above, the plates 24 are positioned perpendicular to the cardboard plate 10 in the developed state (FIG. 3), making one of their longitudinal edges coincide with the fold lines 26 of the transverse walls 16 on the bottom 12. The transverse walls are then straightened at 90 ° relative to the bottom, then the angle returns 18 and the entablatures 22 are folded to bring them into the position they have in FIG. 1. The embodiment of Figure 3 will be described but not claimed.

As can be seen in this figure, the plate 24 has a width 1 greater than the internal height h of the head of the plate 28. Likewise, its length is greater than the internal length of the head of the plate. As a result, during the folding of the cardboard the sides 30, 32 of the folding lines pinch the edges of the plates, thus keeping the latter in place, and this without it being necessary to glue or staple them to the walls transverse 16.

In the alternative embodiment illustrated in FIG. 4, grooves 34 of width substantially equal to the thickness of the reinforcing plates 24 are printed on the cardboard, along the fold lines which surround the transverse walls 16. pads are fitted into said grooves, so that the pads are securely held in place.

The plate 24 of Figure 5 is rectangular and may have on its longitudinal edges the same cuts as those of the transverse walls 16 of the plate.

The plate of Figure 6 comprises a central portion 24 and two side flaps 36 intended to be applied against the transverse wall 16 and the flaps 18 of the tray, thus giving the tray heads increased strength.

In the plate of FIG. 6, cut-shaped parts 38 are provided between the central part 24 and the flaps 36. These flaps 38 are placed at an angle in the corners and thereby ensure even better resistance of the heads of tray.

With reference to FIG. 7, the machine for shaping the plates comprises an assembly 39 which can move vertically and alternately under the action of motor means not shown. This equipment comprises a horizontal base 40 carrying two identical sets of two vertical flat flanges 42, 44 arranged in rows of two.

On each of the flanges 42, 44 are articulated the ends of two identical and parallel rods, respectively 46, 48 and 50, 52, the other ends of which are articulated on hollow parallelepiped punches 54, 56, of section substantially complementary to that of the interior of the plate heads 28. The links 46, 48 are crossed with the links 50, 52, each of said pairs of links forming a deformable articulated parallelogram. The articulation axes of the links on the flanges and on the punches are horizontal and parallel.

In the lower position of the assembly (FIG. 8) the links 46, 48, 50, 52 are in a horizontal collapsed position, the external faces 58, 60 of the punches then being at a mutual spacing equal to the distance separating the fold lines 26 of the cardboard plate 10. In this position, the faces 58, 60 are respectively flush with the openings of two magazines 62, 64 each containing a stack of reinforcing plates 24 in the vertical position. Said external faces 58, 60 are pierced with orifices 68 on which, on the inside of the punches, fit the end of pipes 70, 72 connected to a source of vacuum.

As shown in FIG. 11, on the external faces of the punches are added centering pads 74 intended to come to fit into complementary notches 76 formed on the longitudinal edges of the plates 24.

The operation of the machine will now be described: at the start of a cycle, the machine is in the state shown in FIG. 7. A cardboard plate 10 in the developed state is brought into the centered position, above the movable assembly 39 with its fold lines turned downwards, and it is held stationary in this position by stop means not shown. The moving element 39 is in its low position for which its punches 54, 56 are separated and are respectively flush with the openings of the magazines 62, 64. The punches 54, 56 are correctly centered opposite the opening of the magazines thanks to the pellets 74 which fit into the notches 76. The depression which is exerted through the orifices 68 maintains the first plate 24 of each magazine applied against the contiguous punch.

The moving element 39 then mounts as a unit under the stress of the driving means, causing in their movement the two aspirated plates 24. When the punches 54, 56 arrive at their upper position, the upper edges of the plates are in contact with the lines of folding 26.

Folding elements 80 and 82 then straighten around the plates and punches, the transverse walls 16, and longitudinal 14, the angle returns 18, the entablatures 20 and the flaps 22. As shown in FIG. 9, the plates 32 are therefore pinched all along their peripheral edge between the transverse walls 16 and the lips of the fold lines which surround the latter.

The vacuum is then cut so as to separate the plates 24 from the punches. The base 40 then begins its downward movement. In this movement, the punches 54, 56 approach chent by sliding on the inner faces of the entablatures 20 which are held by the folding elements 82. When the punches are completely released from the entablatures 20, they are free to accompany the base 40 in its downward movement (FIG. 10). Under the effect of the punches' own weight, the links 46, 48, 50, 52 return to their initial horizontal position in FIG. 8, the punches coming tangentially to join the store openings.

The tray can then be removed to make room for another blank.

FIG. 10 shows a particular embodiment of a store for supplying wafers 24. The store comprises four horizontal rods 84, 86, 88, 90 arranged so that the wafers can rest thereon for their notches 76. The rods therefore hold the plates and guide them in their movement towards the opening of the magazine. It goes without saying that the stores can have any other appropriate configuration.

Note that in a stack of trays filled with products, the upper trays only support a very light weight. These plates may therefore not be reinforced. For this, the tray shaping machine may include means which deactivate the vacuum source as soon as the stack of trays formed has a predetermined number of trays. From this moment, the punches will no longer support the pads.

Claims (9)

1. Packing tray of corrugated cardboard, of the type comprising a base 12, two longitudinal walls 14, two transversal walls 16 higher than the transversal walls and each terminating at its ends in two angular returns 18, two horizontal entablatures 20 advancing 'parallel to the base from horizontal upper edges of the transversal walls, and two independent reinforcement sheets 24 applied against the transversal walls and designed to increase the resistance to « bundling of the ends of the tray or the heads 28 which are defined between the base and the entablatures, the said tray being characterized by the fact that the reinforcement sheets 24 are held in position by reason of the. fact that their horizontal edges fit into grooves 34 approximately equal in thickness to the reinforcement sheets and formed by compressing the cardboard along folding lines by which the lateral walls 14, 16, are articulated to the base and to the entablatures, the said reinforcement sheets having for this purpose a height 1 substantially equal to the internal height, h, of the transversal walls 16 puls the sum of the depths of the two grooves 34 into which each of them is fitted.

2. Process for shaping a packing tray from a blank of corrugated cardboard comprising a base 12 to which are articulated, by means of folding lines 26, two longitudinal flaps 14 and two transversal flaps 16 designed to constitute the longitudinal and transversal walls of the tray respectively, these latter terminating at their ends in angular returns 18, two wings 20 articles by means of folding lines to the respective outer edges of the transversal flaps and designed to form entablatures advancing above the base and parallel to the latter, and two rectangular and independent reinforcement sheets 24, characterized by the fact that it consists of the following operations:

laying flat, and opened out, the blanks on which, by compressing the cardboard all along the folding lines by which the lateral walls 14, 16, are articulated to the base 12 and to the entablatures 20, grooves 34 have first of all been formed with a thickness approximately equal to that of the reinforcement sheets 24 ;

fitting the lower horizontal edges of the reinforcement sheets into the grooves formed between the base and the transversal walls 16 and straightening the said sheets so that they are perpendicular to the base ; and

successively the transversal walls 16, the entablatures 20 and the angular returns 18 around the sheets positioned as aforesaid and thus causing them to assume their normal position, each of the reinforcement sheets being thus secured, all along its horizontal edges, between the adjacent transversal wall 16 and the sides of the two grooves into which it has been fitted.

3. Process for shaping a packing tray from a blank of corrugated cardboard comprising a base 12 to which are articulated, by means of folding lines 26, two longitudinal flaps 14 and two transversal flaps 16 designed to constitute the longitudinal and transversal walls of the tray respectively, these latter terminating at their ends in angular returns 18, two wings 20 articles by means of folding lines to the respective outer edges of the transversal flaps and designed to form entablatures advancing above the base and parallel to the latter, and two rectangular and independent reinforcement sheets 24, characterized by the fact that it consists of the following operations :

laying the blank flat in the opened-out state ;

straightening the reinforcement sheets 24, so that they are perpendicular, along the folding lines 26 of the transversal walls on the base ; and

successively the transversal walls 16, the entablatures 20 and the angular returns 18 around the sheets positioned as aforesaid and thus causing them to assume their normal position, each of the reinforcement sheets being thus clamped, all along its longitudinal edges, between the re-entering sides which are formed on the folding lines during the process of folding the adjacent walls.

4. Machine for the performance of the process according to either of Claims 2 and 3, of the type comprising a mobile equipment 39 consisting of two horizontal parallel punches 54, 56, of a cross section equal to the internal cross section of the heads 28, of the packing tray and articulated by means of connecting rods 56, 48, 50, 52, positioned in the form of an articulated parallelogram on a base 40 caused to perform a linear reciprocating movement between an upper position in which the punches are in contact with the cardboard blank to be shaped and a lower position in which the punches are disengaged from the blank, the said machine being characterized by the fact that in the lower position of the equipment 39 the assembly of punches and connecting rods occupies the sunken position, the external vertical faces 58, 60, of the punches then being respectively situated just below the folding lines 26 or below the grooves 34 separating the two transversal walls 16 and the base 12 and respectively on a level with the outlet apertures of two fixed magazines 62, 64, for supplying reinforcement sheets, and that the said external vertical faces are provided with gripping devices 70, 72, capable of gripping the first reinforcement sheet 24 af each magazine in order to position it underneath the folding line 26 or underneath the groove 34 separating the corresponding transversal wall 16 and the base 12, and of holding it until the heads of the tray have been shaped as required.

5. Machine in accordance with Claim 4, characterized by the fact that the gripping devices consist of a vacuum source which sucks the reinforcement sheets into the apertures 68 formed on the aforementioned external faces 58, 60, of the punches.

6. Machine in accordance with either of Claims 4, 5, characterized by the fact that the punches are provided with centering devices enabling them to be correctly positioned opposite the apertures of the magazines when they occupy the low position.

7. Machine in accordance with Claim 6, characterized by the fact that the said centering devices consist of elements 74 adled to the external face 58, 60, of the punches 54, 56, and capable of fitting into indentations 76 formed on the reinforcement sheets.

8. Machine in accordance with any one of Claims 4-7, characterized by the fact that the magazines 62, 64, each consist of horizontal rods arranged to enable the reinforcement sheets 24 to rest thereon by their indentations 76.

9. Machine in accordance with either of Claims 4, 5, characterized by the fact that it includes means for rendering the gripping device inoperative as soon as the pile of trays emerging from the machine comprises a certain preselected number of trays.

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