EP1473238B1 - Packaging system with shrink film retainer - Google Patents

Abstract

The system has a cardboard case (2) including a base (3), a side strip and two sheets in thermo retractable material (9,10). The sheets are connected in a region of junction between the base and two sides of the side strip. A third thermo-retractable sheet (14) is attached at an upper part of the side strip or products and joined to the former sheets by pasting. The sheets are retracted on the products arranged in the case. An independent claim is also included for a process of packaging products with blocking by retractable film.

Description

The present invention relates generally to the field of product packaging inside cardboard boxes, for the preparation and shipping of product orders. More particularly, this invention relates to a product packaging system with wedging by a shrink film, which covers all the products arranged inside a cardboard box, and which ensures, after its retraction, the keeping these products against each other, and against the bottom of the box. Even more especially, the invention is concerned with a packaging system which uses cardboard boxes comprising a bottom and a cardboard side belt, and sheets of heat-shrinkable material connected, by one of their edges, in the region of the junction between the bottom of the body and at least two sides of the side belt of this body.

Such a packaging system is known, in particular, by the French patent 2,589,444 and also by the French patent 2,593,781.

In the systems described by these two documents, there are provided two sheets of heat-shrinkable plastic material, which are respectively connected, by their edge areas, to the junction regions of the bottom of the body and two opposite sides of the side belt of the checkout.

The two sheets of plastic material extend inside the box, from their respective areas of connection to this box. To fill the packaging with the products to be packaged, the initially free portions of the two plastic sheets are first folded outwardly, above the upper edge of the lateral belt of the body. After filling the box with the products to be packaged, the initially free parts of the two plastic sheets are brought back to the inside of the box, above the previously laid products, where these sheets will overlap. The two sheets are then welded to each other, in their overlap zone, so as to form a single film covering all the products. The application of heat for the solder also causes the film to shrink, so as to grip together products. Finally, the box can be closed by a cardboard lid or cap.

• D'une part, les parties extérieures des deux feuilles thermorétractables, qui ne sont habituellement pas maintenues, pendent librement et peuvent prendre des positions plus ou moins anormales, éventuellement en dégageant incomplètement l'ouverture supérieure de la caisse, de sorte qu'elles constituent une gêne pour l'opérateur qui procède au remplissage de cette caisse. Ces parties pendantes risquent aussi de perturber la bonne circulation de la caisse sur un convoyeur.
• D'autre part, l'opération consistant à ramener les deux feuilles vers l'intérieur de la caisse, au-dessus des produits posés et en chevauchement, constitue une manipulation assez importante, qui demande du temps, cette opération restant entièrement manuelle.

As is readily understood, such a packaging system, using two heat-shrinkable sheets respectively connected to two opposite sides of the box, requires heat-shrinkable sheets of a long enough for them to meet and overlap, above the products brought inside the box. As a result, when the two sheets are folded outside to fill the box with the products to be packaged, the outer portions of the two sheets themselves are of significant length, which has various disadvantages:

• On the one hand, the outer portions of the two heat-shrinkable sheets, which are usually not held, hang freely and can take more or less abnormal positions, possibly by incompletely releasing the upper opening of the box, so that they constitute an inconvenience for the operator who is filling the box. These hanging parts may also disrupt the smooth flow of the body on a conveyor.
• On the other hand, the operation of bringing the two sheets inward of the body, above the laid and overlapping products, is a fairly important manipulation, which requires time, this operation remaining entirely manual.

In addition, when the heat-shrinkable sheets are temporarily folded outside the box, and if the height of the hanging parts of the sheets is important, there is the possibility that these parts of the sheets cover labels affixed to the belt of the box, and thus hinder the reading of these labels.

These disadvantages result in a decrease in productivity, for the operation of filling the boxes and heat shrink wrapping products to be packaged. It can also result in insufficient stalling of the products, when the leaves are badly folded before welding and retraction.

The present invention aims to eliminate all of these disadvantages, in particular for the purpose of improving productivity, and while ensuring a reliable setting of the packaged products. A further object of the invention is to protect these products from heat during the heat-shrinking operation of the film.

For this purpose, the subject of the invention is essentially a product packaging system with shrink-film wedging, of the type specified in the introduction, in which there is provided, in addition to the sheets of heat-shrinkable material connected to the region of the junction. between the bottom of the body and the side belt of this body, an additional heat-shrinkable sheet, brought to the level of the upper part of the side belt or the products and joined by welding to the previous heat-shrinkable sheets, to form a single film, which is retracted on the arranged products inside the box, to ensure their rigging.

Preferably, the additional heat-shrinkable sheet has a rectangular shape, corresponding to the horizontal section of the cardboard box.

In the usual case of a cardboard box provided with two heat-shrinkable sheets, respectively connected in the region of the junction between the bottom of the box and two opposite sides of the lateral belt of this box, the additional heat-shrinkable sheet is welded to both first heat-shrinkable sheets in two parallel lines, so as to form, by the meeting of the three sheets, a heat-shrinkable continuous strip.

Insofar as the three sheets used are made of single-oriented heat-shrinkable plastic material, the orientation directions of these three sheets are coordinated, in particular in the transverse direction of the body.

The additional heat-shrinkable sheet may be joined to the first heat-shrinkable sheets by continuous welding lines; the joining of these sheets forms, in this case, a single film with a continuous surface.

In a variant, the additional heat-shrinkable sheet is joined to the first heat-shrinkable sheets by discontinuous welding lines; thus are formed, after retraction of the film, lines of least resistance that can facilitate access to packaged products without cutting tools, so without risk of injury or damage to these products.

The additional heat-shrinkable sheet may be a sheet of the same type, thickness and color as the first heat-shrinkable sheets, which allows to form a homogeneous film by the meeting of all these sheets.

However, it may also be advantageous to use an additional heat-shrinkable sheet whose nature and / or the thickness and / or the color is different from those of the first heat-shrinkable sheets. Such a differentiation makes it possible to optimize the costs, and especially the qualities required for a good retraction of the film; in particular, the use of a leaf additional dark color promotes the retraction of this sheet, in an infrared tunnel.

According to one embodiment of the packaging system which is the subject of the invention, a thermal protection sheet, in particular made of paper, is interposed between all the products arranged inside the box, on the one hand, and the continuous film formed by the joining of the heat-shrinkable sheets, on the other hand. In particular, the thermal protection sheet has a rectangular shape, in correspondence with the horizontal section of the cardboard box and with the surface of the additional heat-shrinkable sheet. Of course, this thermal protection sheet must be able to match the shape of the packaged products.

The present invention also relates to the method of implementation of this additional heat-shrinkable sheet and, where appropriate, the thermal protection sheet.

• on rabat, au-dessus du bord supérieur des faces de la ceinture latérale en carton de la caisse, encore dépourvue de sa coiffe, les parties initialement libres de feuilles thermorétractables raccordées à la région de la jonction entre le fond de la caisse et la ceinture latérale de cette caisse,
• on introduit les produits à conditionner à l'intérieur de la caisse,
• on amène au-dessus de la caisse ou dans celle-ci la feuille thermorétractable additionnelle,
• on soude la feuille thermorétractable additionnelle aux premières feuilles thermorétractables, au niveau de la partie supérieure des faces correspondantes de la ceinture latérale, ou au-dessus des produits disposés à l'intérieur de la caisse, de manière à former un film unique continu, et
• on procède à la rétraction de ce film, par chauffage, de manière à le serrer sur l'ensemble des produits disposés à l'intérieur de la caisse.

Thus, according to another aspect of the invention, the subject of the invention is a process for the constitution of a shrink-wrapped product packaging of the kind in question here, in which, starting from a cardboard box with formed, successively:

• the parts initially free of heat-shrinkable sheets connected to the region of the junction between the bottom of the body and the belt are folded over the upper edge of the sides of the cardboard lateral belt of the body, again without its cap; side of this box,
• we introduce the products to be packaged inside the box,
• the additional heat-shrinkable sheet is brought over or in the box
• the additional heat-shrinkable sheet is welded to the first heat-shrinkable sheets, at the top of the corresponding sides of the lateral belt, or above the products arranged inside the box, so as to form a continuous single film, and
• this film is shrunk by heating so as to tighten it on all the products arranged inside the box.

The operations of welding of the heat-shrinkable sheet additional to the first heat-shrinkable sheets, and shrinkage of the film resulting from the joining of these sheets, are carried out either successively or simultaneously which is easily conceivable insofar as said sheets are made of heat-shrinkable material.

In the case where a thermal protection sheet must be inserted, it is brought inside the body, after the introduction of the products to be packaged and before the supply of the additional heat-shrinkable sheet.

According to a preferred embodiment of this method, the parts of the first heat-shrinkable sheets, folded against the outside of the corresponding faces of the lateral belt of the box, are temporarily held against the outside of these faces, by gluing or by pinching, at least during the introduction phase of the products to be packaged.

The supply of the additional heat-shrinkable sheet is feasible by unwinding a heat-shrinkable film reel, and by cutting the film above a location receiving the body, especially above a conveyor. A workstation is thus constituted which not only unwinds and cuts the film stored on the aforementioned coil, but also advantageously performs the welding of the additional heat-shrinkable film to the first heat-shrinkable sheets.

In the case of the use of a thermal protection sheet, the supply of this sheet is also feasible by unwinding a reel of protective material tape, and by cutting this strip over a receiving location the crate, especially above the conveyor. This is a position of installation of the thermal protection sheet, the supply of this thermal protection sheet being made before the supply and welding of the additional heat-shrinkable sheet.

• L'utilisation d'une feuille thermorétractable additionnelle permet de raccourcir les premières feuilles thermorétractables, qui ne doivent plus se chevaucher au-dessus des produits à conditionner, ce qui diminue la hauteur des parties extérieurement pendantes de ces feuilles, et évite ainsi la gêne constituée par ces parties pendantes.
• Cet avantage est encore renforcé dans le cas où les parties des premières feuilles thermorétractables, rabattues extérieurement, sont provisoirement maintenues contre les faces correspondantes de la ceinture latérale de la caisse.
• Le raccourcissement sensible des parties des premières feuilles thermorétractables, rabattues extérieurement, garantit aussi la visibilité des étiquettes portées par les faces latérales de la caisse.
• Compte tenu de la liaison par soudure des premières feuilles thermorétractables avec la feuille thermorétractable additionnelle, le film continu formé par la réunion de ces feuilles peut prendre place automatiquement à l'intérieur de la caisse, lors de sa rétraction, sans qu'il soit nécessaire de ramener des feuilles manuellement vers l'intérieur de la caisse.
• Les opérations de pose de la feuille thermorétractable additionnelle, et le cas échéant de la feuille de protection thermique, peuvent être aisément automatisées.
• Dans l'ensemble, compte tenu de tout ce qui précède, le système d'emballage objet de l'invention conduit à une augmentation importante de la productivité, sans que la qualité de calage des produits soit réduite.
• Enfin, dans le cas de l'utilisation d'une feuille de protection thermique, les produits placés à l'intérieur de la caisse sont protégés lors de l'opération de rétraction du film, dans le cas où ces produits pourraient se retrouver collés au film rétracté.

Overall, the packaging system, object of the invention, greatly improves the current systems recalled in the introduction, and it provides in particular the following advantages:

• The use of an additional heat-shrinkable sheet makes it possible to shorten the first heat-shrinkable sheets, which must not overlap over the products to be packaged, which reduces the height of the outwardly-hanging parts of these sheets, and thus avoids the discomfort by these hanging parts.
• This advantage is further enhanced in the case where the portions of the first heat-shrinkable sheets, folded outwardly, are temporarily held against the corresponding faces of the lateral belt of the body.
• The substantial shortening of the portions of the first heat-shrinkable sheets, folded externally, also ensures the visibility of the labels carried by the lateral faces of the body.
• In view of the connection by welding of the first heat-shrinkable sheets with the additional heat-shrinkable film, the continuous film formed by the joining of these sheets can take place automatically inside the body, during its retraction, without it being necessary. to bring leaves manually to the inside of the box.
• The laying operations of the additional heat-shrinkable sheet, and if necessary of the thermal protection sheet, can be easily automated.
• Overall, in view of all the foregoing, the packaging system object of the invention leads to a significant increase in productivity, without the quality of calibration products is reduced.
• Finally, in the case of the use of a thermal protection sheet, the products placed inside the box are protected during the retraction operation of the film, in the case where these products could be stuck to the shrink film.

• Figure 1 est une vue en perspective éclatée d'une caisse en carton et des autres éléments, mettant en oeuvre le système d'emballage objet de l'invention ;
• Figures 2 à 9 sont des schémas, en coupe verticale, illustrant les phases successives du processus de remplissage et de formation de l'emballage selon la présente invention :
• Figure 10 est une vue très schématique, en perspective, du poste de déroulage et de pose de la feuille de protection thermique ;
• Figure 11 est une vue très schématique, en perspective, du poste de déroulage et de pose d'une troisième feuille thermorétractable.

The invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing showing, by way of example, an embodiment of this product packaging system with shrink film packaging:

• Figure 1 is an exploded perspective view of a cardboard box and other elements, implementing the packaging system object of the invention;
• Figures 2 to 9 are diagrams, in vertical section, illustrating the successive phases of the process of filling and forming the package according to the present invention:
• Figure 10 is a very schematic perspective view of the unwinding station and laying the thermal protection sheet;
• Figure 11 is a very schematic perspective view of the unwinding station and installation of a third heat-shrinkable sheet.

The packaging system illustrated in the drawing uses a cardboard box 1 of generally parallelepipedal shape, which comprises: a rectangular bottom 2; a lateral belt 3 forming the four vertical faces of the body 1, two large opposite vertical faces 4 and two small opposite vertical faces 5; a rectangular cap 6, closing the body 1 in its upper part.

The rectangular bottom 2 comprises, on its edges, two longitudinal flaps 7 and two transverse flaps 8, which are raised and applied, respectively, against the lower parts of the large faces 4 and the small faces 5 of the lateral belt 3. The flaps 7 and 8 are here applied, and fixed by gluing, on the outer side of the lateral belt 3.

Two rectangular sheets 9 and 10, made of heat-shrinkable plastic material, are respectively bounded, by their edge regions, to the junction regions of the bottom 2 of the body 1 and the two opposite large faces 4 of the side belt 3. For this purpose, in a manner known per se, the border zones of the two sheets 9 and 10 are folded under the lower edges of the corresponding large faces 4 of the lateral belt 3, and these folded edge zones are fixed, in particular pinched and glued, between said large faces 4 and corresponding flaps 7 raised from the bottom 2. Of course, during the process of forming the body 1, the bonding of the edge areas of the two sheets 9 and 10 against the outside of the large faces 4 of the lateral belt 3 is produced before the introduction and the bonding of the bottom 2 to the base of the lateral belt 3.

FIG. 2 shows the box 1 as it stands at the exit of the forming machine, with its two sheets 9 and 10 fixed as just indicated, and extending inside this box 1, the cap is not yet installed so that the body 1 is open at its upper part. Starting from this position, and referring to the diagrams of the following figures 3 to 9, we will now describe the rest of the process, which includes the filling of the box 1 into products to be packaged, and the setting of these products.

• soit de points de colle, réalisés avec une colle visqueuse n'assurant pas une adhérence trop forte ;
• soit de points de pincement, les parties extérieures 9a et 10a des deux feuilles 9 et 10 étant maintenues dans des fentes, encoches ou empreintes appropriées, ménagées dans la zone supérieure des grandes faces 4 de la ceinture latérale 3 en carton.

As shown in FIG. 3, the two sheets 9 and 10 of heat-shrinkable plastic material are first raised against the inner sides of the large faces 4 of the lateral belt 3, and the free end portions of these two sheets 9 and 10 are folded, above the upper edges of the two faces 4, outwardly of these two faces 4. The outer portions 9a and 10a of the two sheets 9 and 10, then coming in front of the upper parts of the two corresponding faces 4 of the belt 3, are held against the outside of these faces 4 at temporary connection points symbolized at 11. It is a question of these connection points 11:

• either glue points, made with a viscous glue not ensuring too strong adhesion;
• or pinch points, the outer portions 9a and 10a of the two sheets 9 and 10 being held in slots, notches or imprints, formed in the upper zone of the large faces 4 of the lateral belt 3 cardboard.

It will be noted that the height of the outer parts 9a and 10a of the two sheets 9 and 10 remains relatively small here, thanks to an appropriate dimensioning of these two sheets 9 and 10.

Then, as illustrated in Figure 4, it is proceeded to filling the box 1 with products 12 to be packaged. The products 12 are introduced through the upper opening of the box 1, well cleared by maintaining the two sheets 9 and 10, and these products are placed on the bottom 2 of the box 1 and / or stacked on each other, without exceeding the top of the side belt 3.

After the box 1 has been filled with products 12, it is possible, as shown in FIG. 5, to supply and to install an optional thermal protection sheet 13. Of rectangular shape, and consisting for example of paper , the protective sheet 13 is introduced through the upper opening of the body 1, and placed above all the products 12.

Then, and in all cases, as shown in Figure 6, it is proceeded to the supply and installation of a third sheet 14 of heat-shrinkable plastic material, of the same nature as the two aforementioned sheets 9 and 10. rectangular shape, the additional heat-shrinkable sheet 14 is brought to the level of the upper edge of the side belt 3, so that the two opposite longitudinal edges of this sheet 14 are placed above the upper folds of the first two sheets 9 and 10 , always held folded on the upper edges of the two opposite faces 4 of the lateral belt 3. It is then welded to the longitudinal edges of the additional sheet 14 on the corresponding areas of the upper folds of the first two sheets 9 and 10. Thus the three sheets 9, 10 and 14 are united in a single continuous strip of heat-shrinkable film, which extends above the upper opening of the body 1.

In the next phase, illustrated in FIGS. 7 and 8, the film is shrunk using appropriate heating means. previously formed by the joining of the three heat-shrinkable sheets 9, 10 and 14. The diagram of Figure 7 shows the beginning of the retraction process, just after the removal or tearing of the links 11 previously made between the first two sheets 9 and 10 and the faces 4 of the lateral belt 3. The diagram of FIG. 8 shows the end of the retraction process, the film constituted by the union of the three sheets 9, 10 and 14 then enclosing all the products 12, with interposition possible of the thermal protection sheet 13, the products 12 being thus wedged inside the body 1.

• Si l'on utilise des feuilles 9, 10 et 14 en matière plastique thermorétractable mono-orientée, telle que polyéthylène mono-orienté, les sens d'orientation de ces trois feuilles 9, 10 et 14 sont coordonnés, de manière à obtenir la rétraction voulue, dans le sens transversal.
• Malgré la longueur initiale de la bande, constituée par la réunion des trois feuilles 9, 10 et 14, le rapport de rétraction du film est suffisamment important (de l'ordre de 5 à 1) pour garantir, après rétraction, l'application et le serrage du film sur l'ensemble des produits 12, même si cet ensemble de produits possède une faible hauteur, ce qui garantit dans tous les cas le calage convenable desdits produits 12.
• En cas d'incorporation d'une feuille de protection thermique 13, celle-ci assure efficacement une protection des produits 12 contre les effets de la chaleur, lors de l'opération de rétraction du film, ce qui a son importance pour des produits 12 ne devant pas être exposés à une chaleur excessive.

About this retraction operation, note the following:

• If sheets 9, 10 and 14 made of mono-oriented heat-shrinkable plastic material, such as mono-oriented polyethylene, are used, the orientation directions of these three sheets 9, 10 and 14 are coordinated so as to obtain the retraction. wanted, in the transverse direction.
• Despite the initial length of the strip consisting of the joining of the three sheets 9, 10 and 14, the shrinkage ratio of the film is sufficiently large (of the order of 5 to 1) to guarantee, after shrinkage, the application and the tightening of the film on all the products 12, even if this set of products has a low height, which guarantees in all cases the proper fitting of said products 12.
• In case of incorporation of a thermal protection sheet 13, it effectively protects the products 12 against the effects of heat, during the retraction operation of the film, which is important for products 12 not to be exposed to excessive heat.

Finally, after wedging of the products 12, the body 1 is closed by placing, at its top, the cap 6. This cap 6 is in particular glued to the top of the side belt 3, by its longitudinal flaps 15 and transverse 16 (see Figures 5, 3 and 9).

The operations of filling of the box 1, setting of the products 12, and finishing of the formation of the box 1, are carried out along a conveyor 17. FIGS. 10 and 11 show two sections of this conveyor 17, on which are carried respectively the laying of the thermal protection sheet 13, then the laying of the additional sheet 14 of heat-shrinkable plastic material.

The station for laying the thermal protection sheet 13, shown in FIG. 10, unwinds a coil 18 of protective sheet, disposed on one side of the conveyor 17. This station comprises, in particular, rollers 19 for guiding the sheet 13 unwound, a member 20 for drawing the end of this sheet 13, and a member 21 for cutting said sheet 13 , which cuts it into rectangular portions adapted to the dimensions of the box 1.

In a fairly similar manner, and as shown in Figure 11, the position of installation of the additional sheet 14 of heat-shrinkable plastic material, placed downstream of the stationary position of the protective sheet, unwinds a coil 22 of heat-shrinkable film, disposed on one side of the conveyor 17. This station comprises, in particular, rollers 23 for guiding the unwound sheet 14, a member 24 for pulling the end of this sheet 14, and a cutter member 25. said sheet 14, which cuts it into rectangular portions of suitable dimensions. In addition, the station comprises means adapted for welding the additional sheet 14 on the first two sheets 9 and 10 already in place, these welding means being constituted for example by two parallel heating ramps 26 and 27.

• en réalisant la fixation temporaire des deux premières feuilles thermorétractables, sur les côtés extérieurs des faces correspondantes de la ceinture latérale, par tous moyens appropriés, ou même en renonçant à une telle fixation et en se contentant du maintien relatif assuré par le seul poids des parties pendantes de ces feuilles ;
• en appliquant le même système à un emballage utilisant plus de deux feuilles thermorétractables liées à la base de la caisse en carton, pourvu que soit aussi mise en oeuvre une feuille thermorétractable additionnelle, soudée aux premières feuilles ;
• en appliquant le système à un emballage dans lequel les premières feuilles thermorétractables sont liées à la base de la caisse en carton par tout mode de raccordement, et en tous points appropriés ;
• en utilisant une feuille de protection thermique en toute matière appropriée, et éventuellement en supprimant cette feuille protectrice ou en la combinant avec la feuille thermorétractable additionnelle;
• dans le procédé, en soudant la feuille additionnelle aux premières feuilles non pas au niveau de bord supérieur de la ceinture latérale de la caisse (comme l'illustre la figure 6), mais en réalisant cette soudure soit latéralement contre les faces extérieures de la ceinture, soit encore à l'intérieur de la caisse, au-dessus des produits venant d'y être introduits ; dans ce dernier cas, les premières feuilles sont ramenées vers l'intérieur de la caisse, avant d'y amener aussi la feuille additionnelle (ainsi posée d'une manière analogue à la feuille de protection thermique) ;
• en adaptant ou en modifiant l'outillage utilisé, par exemple en remplaçant les deux postes successifs, pour la pose de la feuille de protection thermique puis la pose de la feuille thermorétractable additionnelle (selon les figures 10 et 11), par une machine unique regroupant les fonctions de ces deux postes, ou en amenant la feuille thermorétractable additionnelle par déroulement et avance longitudinale au-dessus du convoyeur (au lieu d'une alimentation latérale et transversale).

One would not depart from the scope of the invention, as defined in the appended claims:

• by temporarily fixing the first two heat-shrinkable sheets, on the outer sides of the corresponding sides of the lateral belt, by any appropriate means, or even by waiving such a fixation and by contenting itself with the relative maintenance provided by the weight of the parts alone hanging from these leaves;
• applying the same system to a package using more than two heat-shrinkable sheets bonded to the base of the cardboard box, provided that an additional heat-shrinkable sheet is also used, welded to the first sheets;
• applying the system to a package in which the first heat-shrinkable sheets are bonded to the base of the cardboard box by any method of connection, and at all appropriate points;
• using a thermal protection sheet of any suitable material, and optionally removing this protective sheet or combining it with the additional heat-shrinkable sheet;
• in the process, by welding the additional sheet to the first sheets not at the upper edge of the lateral belt of the box (as shown in Figure 6), but by performing this weld laterally against the outer faces of the belt, still inside the box, above the products just introduced; in the latter case, the first sheets are brought back inside the box, before also bringing the additional sheet (thus laid in a manner similar to the thermal protection sheet);
• by adapting or modifying the tooling used, for example by replacing the two successive stations, for laying the thermal protection sheet and then laying the additional heat-shrinkable sheet (according to FIGS. 10 and 11) by a single machine grouping together the functions of these two stations, or by bringing the additional heat-shrinkable foil by unrolling and longitudinal advance over the conveyor (instead of a lateral and transverse feed).

Claims (18)

1. System for packaging products with immobilization by means of a shrink film covering all the products (12) arranged inside a cardboard box (1) and, after its shrinking, holding these products (12) against one another and also against the base (2) of the box (1), the packaging system using cardboard boxes (1) comprising a base (2) and a lateral band (3) in cardboard and sheets (9, 10) in heat-shrinkable material attached, via one of their edges, in the region of the join between the base (2) of the box (1) and at least two sides (4) of the lateral band (3) of this box (1), characterized in that , in addition to the sheets (9, 10) in heat-shrinkable material attached to the region of the join between the base (2) of the box (1) and the lateral band (3) of this box (1), provision is made for an additional heat-shrinkable sheet (14) brought to the level of the upper part of the lateral band (3) or of the products (12) and connected by means of welding to the previous heat-shrinkable sheets (9, 10) in order to form a single film that is shrunk over the products (12) arranged inside the box (1), in order to immobilize them.
2. Packaging system according to Claim 1, characterized in that the additional heat-shrinkable sheet (14) has a rectangular shape corresponding to the horizontal section of the cardboard box (1).
3. Packaging system according to Claim 2, characterized in that, in the case of a cardboard box (1) provided with two heat-shrinkable sheets (9, 10) attached, respectively, in the region of the join between the base (2) of the box (1) and two opposing faces (4) of the lateral band (3) of this box (1), the additional heat-shrinkable sheet (14) is welded to the first two heat-shrinkable sheets (9, 10) along two parallel lines so as to form, by means of the joining of the three sheets (9, 10, 14), a continuous heat-shrinkable strip.
4. Packaging system according to Claim 3, characterized in that, insofar as the three sheets (9, 10, 14) consist of uniaxially oriented heat-shrinkable plastic, the orientation directions of these three sheets (9, 10, 14) are coordinated, in particular in the transverse direction of the box (1).
5. Packaging system according to any one of Claims 1 to 4, characterized in that the additional heat-shrinkable sheet (14) is joined to the first heat-shrinkable sheets (9, 10) by continuous welding lines so as to form a continuous-surface single film.
6. Packaging system according to any one of Claims 1 to 4, characterized in that the additional heat-shrinkable sheet (14) is joined to the first heat-shrinkable sheets (9, 10) by discontinuous welding lines forming, after shrinkage of the film, lines of least resistance.
7. Packaging system according to any one of Claims 1 to 6, characterized in that a heat-protection sheet (13) particularly made of paper, is inserted between the assembly of products (12) arranged inside the box (1) on the one hand and the continuous film formed by the joining of the heat-shrinkable sheets (9, 10, 14) on the other.
8. Packaging system according to both of Claims 2 and 7, characterized in that the heat-protection sheet (13) has a rectangular shape corresponding to the horizontal section of the cardboard box (1) and to the surface of the additional heat-shrinkable sheet (14).
9. Packaging system according to any one of Claims 1 to 8, characterized in that the additional heat-shrinkable sheet (14) is of a nature and/or thickness and/or color different than those of the first heat-shrinkable sheets (9, 10).
10. Method for forming packaging for products with immobilization by means of a shrink film according to any one of Claims 1 to 9, characterized in that, starting from a preformed cardboard box (1), in succession:

    - the initially free parts of heat-shrinkable sheets (9, 10) connected to the join between the base (2) of the box (1) and the lateral band (3) of this box (1) are folded over the upper edge of faces (4) of the cardboard lateral band (7) of the box (1) that is still without its cover (6);

    - the products (12) to be packaged inside the box (1) are inserted;

    - the additional heat-shrinkable sheet (14) is placed over the box (1) or into the latter;

    - the additional heat-shrinkable sheet (14) is welded to the first heat-shrinkable sheets (9, 10), at the level of the upper part of the corresponding faces (4) of the lateral band (3) or over the products (12) arranged inside the box (1), so as to form a single continuous film; and

    - this film is shrunk, by means of heating, so as to tighten it over all the products (12) arranged inside the box (1).
11. Method according to Claim 10, characterized in that the operations of welding the additional heat-shrinkable sheet (14) to the first heat-shrinkable sheets (9, 10) and of shrinking the film resulting from the joining of these sheets (9, 10, 14) are carried out simultaneously.
12. Method according to Claim 10 or 11, characterized in that, if a heat-protection sheet (13) has to be inserted it is placed inside the box (1) after insertion of the products (12) to be packaged and before insertion of the additional heat-shrinkable sheet (14).
13. Method according to either of Claims 10 and 12, characterized in that the parts (9a, 10a) of the first heat-shrinkable sheets (9, 10) folded over against the outside of the corresponding faces (4) of the lateral band (3) of the box (1) are held temporarily (at 11) against the outside of these faces (4) by means of adhesive bonding or by pinching, at least during the step of inserting the products (12) to be packaged.
14. Method according to Claim 13, characterized in that the folded-over parts (9a, 10a) of the first heat-shrinkable sheets (9, 10) are held temporarily against the outside of the corresponding faces (4) of the lateral band (3) by means of adhesive dots (11) produced with a viscous adhesive.
15. Method according to Claim 13, characterized in that the folded-over parts (9a, 10a) of the first heat-shrinkable sheets (9, 10) are held temporarily against the outside of the corresponding faces (4) of the lateral band (3) by pinching points resulting from slits, notches or impressions produced in the upper zone of the faces (4) of the lateral band (3).
16. Method according to any one of Claims 10 to 15, characterized in that the additional heat-shrinkable sheet (14) is supplied by unwinding from a reel (22) of heat-shrinkable film and by cutting this film above a location receiving the box (1), in particular above a conveyor (17).
17. Method according to Claim 16, characterized in that the unwinding and cutting of the film stored on the reel (22) take place at a work station that also carries out welding of the additional heat-shrinkable sheet (14) to the first heat-shrinkable sheets (9, 10).
18. Method according to both Claims 12 and 16, characterized in that in the case of the use of a heat-protection sheet (13), this sheet (13) is supplied by unwinding from a reel (18) of protective strip and by cutting this strip above a location receiving the box (1), in particular above the conveyor (17).

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