GB2233304A - Stretch wrapping bundles of articles - Google Patents

Abstract

The device for bundle packaging groups of articles, like for instance canned beverages, by means of a cold stretching plastic film which moves from a feeding roll 1 to a collecting roll 8, includes a vertically displaceable platform 14, 15 bearing the articles to be bundle packaged for pushing a curtain of film downwards while the latter is retained at laterally spaced positions by two pairs of oppositely rotating rollers 5, 5' and 66', and stretching said film. The platform bottom can be opened, by pivoting sections 14 & 15 downwardly, and withdrawn upwardly whereby the articles to be bundle packaged are transferred onto the stretched film. The film is transversely sealed at upper and lower spaced locations to complete the bundle and severed just above the lower seal to separate the bundle from the film supply and rejoin the film supply. In addition, an intermediate seal is formed and an opening punched between the upper and intermediate seals to provide a handhole on the finished package (Fig. 7). <IMAGE>

Description

METHOD AND DEVICE FOR BUNDLE PACKAGING GROUPS OF ARTICLES BY MEANS OF A STRETCHABLE PLASTIC FILM This invention concerns bundle packaging of groups of articles, as for instance cans, bottles, and the like, by means of a "stretch type" plastic film, i.e. a film adapted to be cold stretched.

As it is known, in a number of commercial activities, and in particular in supermarkets and in shopping centers, some articles are sold by the group or package, this being particularly the case for beverage bottles and cans, which are kept bundled together by means of a plastic film applied by the bundle packaging method.

According to said method, the film is circumferentially wrapped around the plurality of articles to be bundled together, and then it is subjected to shrinking. For the above type of operation thermally shrinking films are used which, if subjected to the action of heat, undergo a substantial amount of shrinking and in the particular case under examination they firmly tighten the bundled articles. However, the above method has some drawbacks whereby the application thereof to bundle packaging of particular products is precluded. For instance, milk cartons cannot be bundle packaged according to said known procedure, in that the heat would certainly have a damaging influence on milk keeping time.

It is an object of this invention to provide a bundle packaging method which is free from the drawbacks mentioned above and which in particular does not require heating the film and the underlying articles.

According to this invention, said object is met by performing bundle packaging by means of a stretch type plastic film, i.e. cold stretching, rather than by means of a heat shrinking plastic film. The former films are usually manufactured from polyvinyl or polyolefin plastic resins and they have reached a large acceptance in the packaging field owing to their property of being cold stretchable for more than 130%-150% of their length and of being provided with the so called "elastic memory". This expression defines that property of the stretch type films to go back approximately to the starting dimensions after having been cold stretched within a certain percentage. If stretching is applied at higher percentages, the polymer molecules comprising the film get permanently oriented in the stretching direction and the elastic memory property is lost.The inventive bundle packaging method uses a stretch type film which is subjected to stretching in an amount ranging from 130% to 160% of its length, and subsequently it is wrapped circumferentially around a plurality of articles and it is eventually sealed at the ends thereof in order to provide an annular wrapping, the latter then shrinking due to the film elastic memory so that the bundle packaged articles remain firmly confined.

According to a preferred alternative of this invention, the method includes as well forming a handle parallel to the sealing bead, in order to provide a comfortable handling means for carrying the group of articles.

This invention provides as well an apparatus for carrying out said method, whose constructional and operating properties will become apparent to those skilled in this art from the following detailed description of an embodiment thereof, made in reference to the attached drawing, wherein: Figure 1 is a schematic side elevational view of the apparatus according to this invention, at standstill.

Figure 2 shows a schematic side elevational view of the same apparatus, in operation; Figures 3, 4 and 5 show schematically side elevational views of the above apparatus, during sequential operating steps; Figure 6 shows an enlarged top plan view of a detail of the sealing device; and Figure 7 shows a group of twelve cans bundle packaged together according to the inventive method and by means of the apparatus of this invention.

Referring now to Figure 1, as it is shown therein, the inventive apparatus substantially comprises a roll 1 mounted on an idle shaft 2, and stretchable film 3 unrolls therefrom and, after winding around an idle roller 4, goes through two pairs of counterrotating rollers 5, 5' and 6, 6', properly spaced from each other, and it slides thereafter upon idle roller 7 to roll up on collecting roll 8 operated by a motor driven shaft 9.

The distance between the two pairs of oppositely rotating rollers 5, 5' and 6, 6' is selected in such a way as to leave sufficient room therebetween to allow free passage of loading platform 10-where a dozen cans 11 may be arranged while being laterally retained by sides 12 and 13 of platform 10. The bottom of platform 10 comprises two wings 14 and 15, which are hingedly connected, at 16 and 17 respectively, to the bottom edge of platform sides 12 and 13. A properly controlled downwards rotation of both wings 14 and 15 causes platform 10 to open and the content thereof, like for instance cans 11, to freely exit therefrom.

Platform 10 may perform a reciprocating vertical motion between a position of maximum elevation, which is shown in Figure 1, and a position of minimum elevation, which is shown in Figure 2. In the maximum elevation position, platform 10 is located at the level of a conveyor belt (not shown in the drawing) which is adapted to transfer, in a way known per se, cans 11 between sides 12 and 13 of platform 10. Two photocells are located near the point of maximum elevation and of minimum elevation respectively, reached by the bottom of platform 10. The size of platform 10 is selected in such a way as to give a suitable seat to the group of articles to be bundled together, and therefore it may vary between fairly wide limits. In this particular case, when a dozen cans 11, for instance one liter cans, have to be bundle packaged together, the size is rather small.

Rolling up of film 3, caused by rotation of motor driven shaft 9 and of collecting roll 8, takes place through a free sliding between idle rolls 4 and 7 and through the two pairs of counterrotating rollers 5, 5' and 6, 6'.

Said free sliding is interrupted when the two pairs of oppositely rotating rollers 5, 5' and 6, 6' are controlled to change their rotation direction. Said change of direction causes the forward moving film to stop and to be subjected to a certain amount of tension in the span between the two pairs of counterrotating rollers. Said control is given to the oppositely rotating rollers by a suitable device, in the moment when photocell 18 is blanked by passing platform 10, when the latter starts moving downwards.

While continuing to move downwards, platform 10 comes into engagement with film 3 and the latter, being now retained from freely sliding between the two pairs of oppositely rotating rollers, is subjected to a longitudinal stretching by said platform. By suitably controlling the relative velocities of oppositely rotating pairs of rollers 5, 5' and 6, 6', as well as the stroke length of platform 10 between the end positions thereof, it is possible to properly control the stretching percentage film 3 is to be subjected to in the span included between the two pairs of oppositely rotating rollers 5, 5' and 6, 6'. When photocell 18 is blanked by the passage of the bottom of platform 10, besides causing the change in rotating direction of the pairs of oppositely rotating rollers, the rotating motion of motor driven shaft 9 of collecting roll 8 is caused to stop as well.

Referring now to Figure 2, as it is shown therein, platform 10, while proceeding in the downwards stroke thereof, has reached with the bottom thereof the level of photocell 19, whereby the latter is blanked. During said downwards stroke, platform 10 has dragged along the span of film 3 located between the two pairs of oppositely rotating rollers 5, 5' and 6, 6' causing it to elongate and therefore to strech in a longitudinal direction. By said motion, platform 10 has provided a substantially U-shaped wrapping, open at the top and on the sides, and it has transferred a dozen cans 11 inside said open wrapping.

Referring now to Figure 3, as it is shown therein, blanking of photocell 19 has caused a downwards rotation of both wings 14 and 15, hingedly connected at 16 and 17 at the bottom of platform 10. Due to said rotation, film 3 is further stretched in the center region thereof, whereby a uniform stretching of the span of film 3 retained between the two pairs of oppositely rotating rollers 5, 5' and 6, 6' is obtained. The downwards rotation of wings 14 and 15, besides causing a further stretching of film 3, transfers under the action of gravity the dozen cans 11 towards the bottom of the wrapping, open in a U shape, which has been formed by stretching a length of film 3.

At this point, a timer (not shown in the drawing) controls in a known way the start of platform 10 upwards stroke. When the lower edges of platform 10 wings 14 and 15 traverse again in front of photocell 19, the latter simultaneously controls a closure rotation of said wings, as well as an approaching motion of the two sealing device facing components 20 and 21, as it will be described in the following referring to Figures 4 and 5. Figure 4 shows that lower wings 14 and 15 of platform 10 have eventually closed and the empty platform proceeds in its upwards stroke. At the same time, sealing device components 20 and 21 keep getting closer to each other. As it will be better described in the following referring to Figure 6, the sealing device includes as well a punch, adapted to cut perforations in film 3.

Figure 5 shows how, under the action of mutual approaching motion of sealing device components 20 and 21, two facing regions of film segment 3 located immediately above the dozen cans 11 are brought into direct mutual contact. At this point, the lower and upper sealing plates of the sealing device, suitably controlled, cause the mutually contacting regions of film 3 to melt together, whereby they get sealed.

At the same time, the punch located between the upper and lower sealing plates cuts an opening between the two sealed regions, of a size suitable for allowing at least one hand to pass through. In such a way a convenient handle for carrying the dozen bundle packaged cans 11 is obtained. Owing to the film elastic memory, said film shrinks while tightly confining the bundle packaged cans, whereby the main object of this invention is fulfilled.

While continuing in its upwards stroke, platform 12 moves again across upper photocell 18 which controls again the filling of platform 10 with a new group of cans 11. At the same time, shaft 9 driving motor is actuated again and it causes film 3 to move towards the collecting roll, whereby the sealing bead provided by the upper plates of the sealing device is made to move beyond the pair of oppositely rotating rollers 6, 6' and it does not appear on the next dozen of bundle packaged cans.

Fig. 6 shows components 20 and 21 of sealing device 2, in a detailed view. In component 20 there is shown the lower sealing plate 22 above which there is provided, in the same order they are mentioned herein, the punch male member 23, intermediate sealing plate 24, cutting device blade 25, and upper sealing plate 26. In positions corresponding to those of the parts mentioned above, component 22 is provided with sealing counterplate 27 and above the latter, in the same order they are ment ioned herein, with punch female member 28, intermediate sealing counterplate 29, cutting device female member and upper sealing counterplate 31.

When the two components 20 and 21 move into mutual engagement, two layers of film 3 are cought therebetween, the first comprising the downward moving span of the stretched film, and the second comprising the upward moving span thereof. Under the action of sealing plate 22, which cooperates with counterplate 27, the pair of overlying layers of film 3 are sealed along the whole area engaged by plate 22 and by counterplate 27. At the same time, both film layers in the area located above the area sealed by plate 22, get severed by punch cutting member 23 which moves through matching female cavity 28. In such a way, the punch takes out an area of film and provides a large opening, adapted to allow at least one hand to go through, in order to form a handle for carrying the bundle packaged cans.On top of the handle there is provided a second horizontal sealing line, by means of intermediate plate 24 which cooperates with counterplate 29. At the same time, the package of bundled cans is severed from the remaining film by the action of blade 25, moving into matching cavity 30 of component 21. The free end of the downward moving film span is sealed, at the opposite end, by plate 26 cooperating with counterplate 31. Once this last seal is performed, rotation of collecting roll 8 will cause the sealing bead to move beyond the pair of oppositely rotating rollers 6, 6', and unrolling of a corresponding span of film from feed roll 1. In such a way, a new span of film 3, free from sealing beads, is made available for bundle packaging operation of a new group of cans 11.

The package of bundled cans 11 is supported, immediately before, during and after the operation of severing, by cutting, from the remaining film, by an unloading platform which is not shown in the drawing. Said platform may be any known type, but it is preferably displaceable whereby the bundled package may be quickly transferred to a downstream located conveyor belt.

Figure 7 shows a package of cans 11 after bundling according to the method, and by means of the device, of this invention. As it is shown, the cans are tightly confined flanking each other, by film 3 since the latter, owing to its elastic memory has correspondingly shrunk after having been subjected to stretching in a longitudinal direction. The bundled package is conveniently provided with a handle 32 whose grabbing is made easier by opening 33 provided therein by punch 23.

In the embodiment shown in the drawing, the cans are circumferentially bundle packaged but, as it should be apparent, they may be bundle packaged for instance around an orthogonal plane, as for instance around the can bases. Further modifications and/or additions may be made by those skilled in this art to the embodiment described herein and shown in the attached drawing: said embodiment having been shown and described herein for exemplary and non limiting purposes only.

Claims (9)

1. A method for bundle packaging a plurality of articles by wrapping said articles within a wrapping comprising a plastic material film, characterized in that use is made of a cold stretching plastic film which is subjected to stretching,it is wrapped around the plurality of articles,it is closed by sealing in a ring-like fashion, and it is allowed to shrink owing to its elastic memory.

2. A method according to claim 1, characterized in that the plastic film fed out of a roll, is subjected to stretching and it is wrapped around a group of articles in such a way as to form a tube-like wrapping whose ends are sealed together, a second seal being performed parallel to the first and a longitudinal cut being performed parallel to the second seal, in order to severe the sealed package from the remaining film, said film being pieced together again by means of a further seal, and rolled up around a collecting roll.

3. The method according to Claim 2, characterized in that between the first line of sealing and the second line of sealing there is provided an opening opted to allow at least one hand to pass through.

4. The method according to Claim 3, characterized in that plastic film stretching is performed through the motion of said displaceable platform which feeds the articles to be bundle packaged.

5. A bundle packaging device for carrying out the procedure according to the previous Claims, characterized in that it substantially comprises a roll for feeding the film, and a roll for collecting the film, and two pairs of oppositely rotating parallel rollers are located therebetween and they are opted to clamp the ends of a span of plastic film, a loading platform adapted to move vertically through said pair of oppositely rotating rollers, and provided with a collapsible bottom for allowing the articles arranged on the platform to be unloaded while confined within a substantially cylindrical wrapping comprised of the plastic film, a sealing device for said tube-like wrapping, and a cutting device for severing the bundled package from the remaining plastic film.

6. The device of Claim 5, characterized in that it includes a second sealing device, arranged parallel to the first one, and a punch device provided therebetween.

7. The device of Claim 6, characterized in that the door which can be opened at the bottom of loading platform (10) comprises two wings adapted to rotate downwards around hinges connecting said wings to platform (10).

8. A bundle packaging device substantially as described above and as shown in the attached drawing.

9. A method of bundle packaging according to claim 1 substantially as hereinbefore described.