EP0575536B1 - Wrapping method using folded flexible sheets - Google Patents

Abstract

PCT No. PCT/FR92/00228 Sec. 371 Date Sep. 15, 1993 Sec. 102(e) Date Sep. 15, 1993 PCT Filed Mar. 13, 1992 PCT Pub. No. WO92/16429 PCT Pub. Date Oct. 1, 1992.Wrapping for convex or similar bodies, made from a thin sheet, consisting of symmetrical folds, from which there are obtained, by folding, changes in direction making it possible to approximate, as best as possible, the profile to be wrapped and the folds of which are fastened at their ends. In order to change the direction of the folds, each rectangular strip (9 ) is folded on itself along an oblique line (12) enabling the internal (10) and external (11) arrises to be inverted in order to become, respectively, external arrises (13) and (14), the angle (15) formed by the oblique folding line (12) and the internal (10) and external (11) arrises determining the variation in the direction of the folds.

Description

The invention relates to a method of packaging a convex body, or equivalent convex volume circumscribed to any body, produced from a thin film.

Since the creation of the rectangular, simple or composite sheet of paper used to package cheeses, burgers and rolls, a pleated film-based packaging has been created, the folds being asymmetrical, fixed on the edges , allowing to wrap the convex bodies; these are patents FR-A-2595666, FR-A-2628719 and FR-A-2668457, which describe various kinds of packaging using coated plies; in these patents the folds are defined from successive bands forming rectangles, parallelograms or elongated trapezoids; of width A and B, A different from B.

The present invention, as defined in claim 1, relates to the production of pleated packaging produced from a strip of rectangular film in which the folds are formed from a succession of equal rectangular strips; which corresponds in the patents cited to the case A = B and in which the radius of the upper and lower circles is zero.

The packaging, object of the invention, is produced in a preferred version from a rectangular sheet of length L and width K.

Figure 1 shows a fold formed by symmetrical folds.

FIG. 2 represents the previous folding, the ends of which have been fixed.

FIG. 3 represents a folding of the type Fig. 1 carried out on a sheet one side of which has been folded longitudinally to form a double thickness of film.

FIG. 4 represents the folding of FIG. 3, an angle of which has been entered in the zone where there are two thicknesses of film.

FIG. 5 represents the folding of FIG. 3 deployed to obtain a change of direction of the folds according to the invention.

FIG. 6 represents a package according to the invention comprising two changes of direction.

Figure 7 shows a package according to the invention deployed around an object.

FIG. 8 represents a method of fixing the folds by adding a flexible tape.

When the symmetrical folds formed of identical rectangular strips 1 (fig. 1) of width A 2 and length K 3 are folded, the N folds are exactly superposed (N being the number of folds), each fold being formed of two successive rectangular bands 1 connected by a folding edge 4, two successive folds also being interconnected by a folding edge 5; once folded, the packaging is in the form of a parallelepiped (fig. 2) of length K, width A and thickness 6 corresponding to the number of N folds; the thickness 6, of the folds to be fixed at their ends 7 and 8, is directly proportional to the number N of folds; the fixing techniques must be adapted according to the uses to be made of them and the number N of folds.

The folds are attached to the ends in various ways; first there are the methods of fixing sheets to each other, from binding, such as stapling, pinching, sewing, gluing on the edge, the use of a ring passing through a hole made with a cookie cutter, this list not being exhaustive; then there are the high frequency, ultrasonic, thermal welding methods of films that can be welded or made weldable by depositing a layer of plastic material or single-sided or double-sided heat-activated adhesive, this list not being exhaustive. The attachment may concern the entire width A of the ends 6 and 7 of the plies and the two sides of the film. But it can also interest the entire width A of the ends 6 and 7 of the folds, but only on one side of the film; under these conditions the faces of each fold are fixed two by two and each fold connected to the other by an edge 5; the edges 4 can deviate from each other. It may be advantageous to ensure that the binding only affects one side of the film and over only part of the width A, from the end of the folds, starting from the edge 4 (fig. 1) joining the two rectangular strips 1 which constitute it; for example, it is possible to fix each fold at its end over a length A / 2 starting from the edge 4, leaving free the zone situated on the side of the edge 5; the pleat fixing zone can then be partially deployed, making it possible to prevent the ends of the plies from remaining in a bundle. When the end is deployed, each fold fixing zone is then separated from the next by a strip of film of width A; it constitutes a border making it possible to improve the aesthetics of the whole; however, it should not be forgotten that the fasteners thus produced work on peeling during deployment of the packaging, that the fixing remains fragile and that the packaging can be prematurely damaged.

avec $\text{Pl=3,14*D}$

qui correspond au périmètre de la surface cylindrique, K le coefficient de recouvrement de l'emballage et $\text{A=L/N}$

; K est inférieur à l dans le cas d'un recouvrement partiel de l'objet à emballer; si K est égal ou supérieur à l, il peut y avoir recouvrement total de l'objet et même l'emballage peut se superposer à lui-même pour réaliser la fermeture. Le nombre de plis maximum toléré est fonction de leur mode de fixation de leurs extrémités et il peut varier de manière importante. Le déploiement de la partie centrale de l'emballage, tel qu'il est réalisé, ne permet pas que les extrémités se rabattent systématiquement vers le centre des parties supérieures et inférieures de l'objet à emballer; les plis qui sont généralement assez larges ont du mal à se déployer pour recouvrir les surfaces supérieures et inférieures. Une manière de faciliter ce déploiement consiste, par un pliage approprié, à donner à l'emballage plié une forme plus complexe (fig.6); une façon de procéder est de chercher à obtenir des plis, non plus constitués de bandes rectangulaires planes 1 (fig.1) mais de bandes rectangulaires 9 (fig.6) pliées sur elles-mêmes de manière à leur donner une direction choisie par avance; par exemple on peut donner à l'emballage plié (fig.6) la forme d'un croissant de lune en faisant deux changements de direction; pour obtenir ce résultat, on opère de la façon suivante: dans leur partie centrale 25 (fig.6 et 7) les plis sont de même nature que ceux décrits précédemment avec une arête intérieure 10 qui sera en contact avec l'objet à recouvrir et une arête extérieure 11 qui sépare deux arêtes intérieures 10 successives: pour changer la direction des plis, on opère un pliage sur elle-même de chaque bande rectangulaire 9 suivant une ligne 12 joignant en oblique les deux côtés de longueur K formant deux arêtes intérieure 10 et extérieure 11 successives, et deux bandes 1 successives étant pliées symétriquement, l'une par rapport à l'autre, par rapport à leur arête commune 10 ou 11; dans ces conditions les arêtes sont inversées; les arêtes intérieures 10 deviennent des arêtes extérieures 13 et les arêtes extérieures 11 deviennent des arêtes intérieures 14; l'angle 15 que fait la ligne oblique 12 de pliage avec les arêtes intérieures 10 et extérieures 11 détermine la variation de la direction des plis, qui peut varier dans une large plage, allant de l'angle aigu à l'angle obtus en passant par l'angle droit. Si on fait le même changement de direction aux deux extrémités 16 et 17 afin d'obtenir un profil plié en forme de U ou de croissant de lune, afin de s'approcher au mieux du demi-profil du produit à emballer; on peut obtenir ainsi, par dépliage de l'emballage correctement dimensionné, par exemple, autour d'une surface cylindrique (fig.7), des plis ouverts 18 sensiblement parallèles qui restent bien formés le long de la surface cylindrique et des plis sensiblement rayonnants 19 mais bien formés sur les parties supérieures et inférieures. Pour réaliser ce type d'emballage et pour lui garder son aspect esthétique, il faut qu'il soit suffisamment dimensionné; en effet, sa conception en fait un emballage permettant de réaliser une cavité ayant une forme relativement bien définie; et si on veut l'utiliser pour emballer une forme trop différente, de celle pour laquelle il a été dimensionné, on risque de perdre la qualité esthétique des plis. Contrairement aux emballages décrits dans les brevets cités, les plis s'ouvrent en accordéon sans qu'il y ait glissement du film sur lui-même; en conséquence on peut utiliser des films relativement plus rigides.When we develop this packaging, by deploying the folds in their central area, we form a cavity in which we can accommodate an object. Suppose, to facilitate the explanations, that the object to be wrapped is a cylindrical volume of revolution of diameter D and height H. In the version described, the packaging forms, before unfolding, a rectangular parallelepiped (fig.2); to avoid having too many folds, which creates fixing problems at the ends, it is advantageous to limit it; in the case of the packaging of a cylinder we have K substantially equal to H + D and $\text{L = K * Pl}$

with $\text{Pl = 3.14 * D}$

which corresponds to the perimeter of the cylindrical surface, K the covering coefficient of the packaging and $\text{A = L / N}$

; K is less than l in the case of partial recovery of the object to be packaged; if K is equal to or greater than l, there can be total covering of the object and even the packaging can be superimposed on itself to achieve closure. The maximum number of folds tolerated depends on their method of fixing their ends and it may vary significantly. The deployment of the central part of the packaging, as it is produced, does not allow the ends to systematically fold back towards the center of the upper and lower parts of the object to be packaged; folds that are usually quite wide have trouble deploying to cover the top and bottom surfaces. One way to facilitate this deployment consists, by appropriate folding, in giving the folded packaging a more complex shape (fig. 6); one way to do this is to try to obtain folds, no longer made up of flat rectangular bands 1 (fig. 1) but of rectangular bands 9 (fig. 6) folded on themselves so as to give them a direction chosen in advance ; for example, we can give the folded packaging (fig. 6) the shape of a crescent moon by making two changes of direction; to obtain this result, the procedure is as follows: in their central part 25 (fig. 6 and 7) the folds are of the same nature as those described above with an internal edge 10 which will be in contact with the object to be covered and an outer edge 11 which separates two successive inner edges 10: to change the direction of the folds, a rectangular strip 9 is folded on itself along a line 12 joining the two sides of length K obliquely forming two inner edges 10 and exterior 11 successive, and two successive bands 1 being folded symmetrically, one with respect to the other, with respect to their common edge 10 or 11; under these conditions the edges are reversed; the inner edges 10 become outer edges 13 and the outer edges 11 become inner edges 14; the angle 15 made by the oblique fold line 12 with the internal 10 and external 11 edges determines the variation in the direction of the folds, which can vary over a wide range, going from the acute angle to the obtuse angle while passing by the right angle. If we make the same change of direction at both ends 16 and 17 in order to obtain a folded profile in the shape of a U or crescent moon, in order to approach to the best of the half profile of the product to be packaged; one can thus obtain, by unfolding the correctly dimensioned packaging, for example, around a cylindrical surface (fig. 7), substantially parallel open pleats 18 which remain well formed along the cylindrical surface and substantially radiating pleats 19 but well formed on the upper and lower parts. To achieve this type of packaging and to keep it aesthetic, it must be sufficiently sized; indeed, its design makes it a packaging making it possible to produce a cavity having a relatively well defined shape; and if we want to use it to package a shape that is too different from the one for which it was designed, we risk losing the aesthetic quality of the folds. Unlike the packaging described in the cited patents, the folds open in an accordion without the film sliding on itself; therefore relatively stiffer films can be used.

It is obvious that this technique can be applied to folds initially formed, for example, of bands in the form of symmetrical parallelograms two by two or equal isosceles trapezoids and symmetrical two by two, along the oblique side joining the two parallel bases, can be superimposed by folding, make several successive changes of direction, this list of possibilities is not exhaustive.

One way of making this kind of folding manually with a change of direction is to first define strips of width A and length K (fig. 3); to fold the end 20 longitudinally whose direction you want to change, and to perform the folding as described above of the rectangles 1 (fig. 1) one side of which 20 (fig. 3) has two thicknesses of film with a folding edge 23. Then we enter each angle 22 of the folds obtained to mark the oblique line 24 (fig.4) which will allow each strip 1 to fold back on itself; once the edges are well marked, unfold the previous fold (fig.4) and put in place the following folds the creases made (fig. 5); all that remains is to fold the folds over each other and fix the ends as shown (fig. 6). It can be seen that in the direction change zone, there is a doubling of the number of layers of superimposed films, which is a limiting factor in the number of plies. In a variant of the invention, it may be advantageous, for certain applications, to fix only one of the ends to make products, having the shape of a bell or a horn, when they are deployed, to protect for example an object, placed on a table, from dust or simply a cone of fries. FIG. 8 represents a method of fixing the pleats or of reinforcing their fixing by adding a flexible tape. This flexible tape 26 (fig.8) is fixed by welding or gluing and avoids the work of peeling the fixing of the folds in the vicinity of the edge 13 when it only interests one side of the film; the strip alone can constitute a method of fixing the folds.

Claims (10)

1. Folded packaging with a thin film base for convex or similar-shaped objects, wherein it is formed from a folding along identical symmetrical two-by-two rectangular strips (1) or parallelogram-shaped strips or trapezium-shaped strips irrespective of their shape with respect to the common folding edge (4) being superimposed precisely and fixed together at at least one of their ends.
2. Packaging according to claim 1, whererin the folds change direction via the strips being folding back along an oblique line (12) enabling the internal (10) and external edges (11) to be inverted so as to respectively become outer edges (13) and (14).
3. Packaging according to claim 2, wherein the two ends (16) and (17) of the strips constituting the folds change direction so as to form a U when it is folded so as to ressemble as much as possible the half-profile of the object to be packed and give the folds an aesthetic shape when the packaging is deployed around the object to be covered.
4. Packaging according to claim 2 or 3, wherein the change of direction of the folds may be effected manually via the prior longitudinal folding of a strip (20) along an edge (23) of the starting sheet prior to folding into symmetrical folds and then by bending in their corners (22) so as to mark the oblique lines (24) prior to deployment making it possible to change the internal (10) and outer (11) edges respectively into outer (13) and inner (14) edges.
5. Packaging according to any one of the preceding claims, wherein the folds comprise a change of direction or several similar or different changes of direction.
6. Packaging according to any one of the preceding claims, wherein the fixing of the ends is carried out by using binding or brocading techniques or those relating to the hot welding of plastic materials or heat-activable glues.
7. Packaging according to any one of the preceding claims, wherein the fixing of the ends is effected by securing the ends of the strips forming the folds to their two faces.
8. Packaging according to any one of claims 1 to 7, wherein the fixing of the ends is only effected along one face of the sheet so that the two successive strips connected by one folding edge (4) constituting a fold are interconnected at their ends, but two successive folds are solely interconnected by one folding edge (5).
9. Packaging according to claim 9, wherein the fixing of the ends effected from the edge (4) only concerns one portion of the width of the strips of the fold concerned and leave the portion of the strip situated on the side of the edge (5) unglued so as to allow for a partial separation of the folds.
10. Packaging according to claim 10, wherein the fixing of the ends is reinforced by a flexible band (26) able to be possibly used alone for fixing the end of the folds.

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