CZ20001452A3 - A method and apparatus for sealing food cans and beverage cans - Google Patents

Abstract

A sheet (91) of thermoformable plastic material is heated and placed on the top of a group of cans (4). This sheet (91) then adheres to the surface of the top of the group of cans (4) by means of a pressure action exerted on the top of the sheet (91) and exerted by a flexible flexible insert (823) in the areas surrounded by the circular edge (414) of the can, and by means of compressed air in the areas outside the circular edge (414) to press the sheet (91) downwards. That part of the sheet (91) which adheres to the top of the group of cans (4) is separated from the rest of the sheet (91). The sheet (91) is first heated to a suitable temperature so that after subsequent cooling it retains its shape and remains adhered to the surface of the top of the cans (4).

Description

Technical area

The invention relates to the hygienic protection of packaging cans for food products and beverages, and in particular beverage cans, which are provided with a tear-off opening on their upper side, through which the beverage is consumed, possibly by placing the can directly to the mouth.

State of the art

The widespread practice of storing beverages in cans has caused a general problem of ensuring the health protection of users.

In this regard, cans are then transported and stored after being filled without any practical means of protecting them from dust or other far more dangerous pollutants, which makes the consumption of beverages highly unhygienic when pouring the beverage into a glass or even when the user drinks the beverage directly from the can.

The situation is further aggravated by the appearance of cans in which the opening tab is not torn off, but instead bends downwards into the interior space • 4 ·

cans, so it comes into direct contact with the contents of the can.

It is created like this need to ensure protection upper pages cans with a pull tab loop, before dust and other pollutants. They are known ways of ensuring protection upper pages

cylindrical objects that generally have the same shape as cans.

In patent document FR-A-2 320 241, a method and apparatus for covering a group of batteries are described, whereby these batteries are covered with a plastic strip which is pressed onto the top of the battery by using heat and pressure applied to the material, thereby forming a cover for each individual battery of the group.

The batteries can be arranged in various patterns, they can be in a single row or in two rows, or they can be arranged in a circle. A groove inside the cover allows air to escape from the cover.

This type of packaging is not suitable for cans, as the different arrangement of their upper part makes it impossible for such a cover to adhere perfectly to the top of the can.

The problem of ensuring protection of the top of cans from dust and other contaminants has been solved by the solution described in international patent application PCT/EP 97/03716.

Said solution comprises heating a film of thermoformable plastic material and placing said film on the top of a can, and then ensuring that said film adheres to the surface of said top of the can by removing air contained between said surface and the film. Finally, the part of the film that has adhered to the top of the can is separated from the rest of the film.

During the described process, the film is heated to a suitable temperature so that the film is able to meet the conditions of thermoformability, and then, after subsequent cooling, it solidifies and remains closely adhered to the surface area it covers, while maintaining and retaining its shape.

A certain lid is thus formed, consisting of a part of the foil which fits the top of the can and which covers this top, and which can be easily removed from the can and put back on it in order to cover the area which includes the opening of the can and the entire top of the can, as well as the upper edge which comes into contact with the user's lips, so that this area is maintained in good hygienic conditions.

Such improvements are also known in which the covering means are designed for groups of at least two cans, so that they are provided to packages of two or more cans, connected by a single carrier strip, the lids of which are thus simultaneously protected from contamination.

• · ··· ·· ·· • · · · · · · · · · » • ·

The above-mentioned prior art is described in international patent application PCT/EP 97/03716, which was published as WO 98/04459, and which is in the name of the same applicant.

The method and device described in the above-mentioned published international patent application WO 98/04459 are suitable for further improvement, particularly with regard to the removal of air contained between the foil protecting the upper part of the can and the lid of the can.

The essence of the invention

In the known prior art, the smaller the amount of air to be evacuated, the easier it is to achieve the negative pressure necessary for the evacuation of air.

The object of the present invention is therefore to significantly reduce the amount of air to be exhausted, and possibly to eliminate it completely, with the subsequent simplification of the device in question.

In accordance with the subject matter of the present invention, in order to achieve the above object, a film of thermoformable plastic material is heated and placed on the top of a can or a group of cans, whereby it is ensured that this film adheres to as large an area of the surface area of said top of the can as possible by means of a pressing action which acts on the top of the film in order to press the film downwards.

• · · • · · · · · • ·

According to the present improvement, said pressing action can be performed either by the action of a convex deformable elastic insert which is pressed against the upper part of the can in order to ensure adhesion of the foil starting from the center of the can lid, or by the dynamic action of a stream of compressed air directed into the center of the can lid.

In both cases, the pressing action is expected to be accompanied by the exposure of the part of the foil resting on the lid to the action of vacuum from below, removing very small residuals that may be formed on the periphery of the lid near the protruding edge, which is created by its melting.

sides for air pockets,

In accordance with one particularly advantageous embodiment of the present invention, it has been found that it is possible to completely remove all air even without the presence of a vacuum or negative pressure.

In accordance with the subject matter of the present invention, a method has been developed for closing packaging cans, the upper part of which is formed by a substantially flat upper end of the can, its frustoconical neck and a circular rim connecting the flat upper end to the neck, comprising the steps of placing a portion of a film of thermoformable plastic material on the upper part of the can in contact with the upper edge of its rim to define a closed chamber in combination with said upper edge of the rim, heating the film to a suitable temperature so that it can meet the thermal conditions.

ΦΦΦΦ φφ formability, removing air from said chamber, whereby the foil, after cooling and solidifying, then adheres tightly to the surface of the flat upper end of the can, which overlaps and maintains its shape.

from the pressure compressed

The essence of the subject matter of the present invention lies in the fact that air is removed from said chamber by means of an action exerted by a flow of air acting on the upper part of the belt covering the upper part of the cans.

Pressure action, compressed air, with pressure action, circular edge of the can, flexible elastic inserts.

derived through current preferably carried out in combination limited to an area, delimited and carried out through

The action of the flexible insert is preferably carried out in combination with the action of the edge of the rigid cup containing this flexible insert.

The action of the insert is preferably carried out before the action of the edge of the fixed cup.

The pressing action exerted by means of the flexible elastic insert is preferably carried out before the pressing action exerted by means of the compressed air.

The pressing action exerted by the insert preferably starts from the center of the can lid and extends towards the circumference defined by the circular edge.

The portions of the foil adhering to the top of the cans are preferably separated by cutting along a closed line located on the frusto-conical neck of each individual can.

The portions of the foil adhering to the top of the cans may also advantageously be separated by cutting along a closed line which closely encloses the outer edge of the line forming the envelope of said top of at least two cans.

To carry out the above method, in accordance with the subject matter of the present invention, a device for closing packaging cans arranged in the recesses of the trays has been developed, comprising an overlapping first centering plate provided with a plurality of first through-holes corresponding to the recesses lying below for receiving the upper part of the cans so that they protrude above the upper surface of the centering plate, means for placing a heated strip of plastic material over the protruding upper part of the cans, means for ensuring that said strip adheres to the upper part of said cans and means for separating that part of the strip that adheres to the upper part of the cans from the rest of the strip.

The essence of the device in question lies mainly in the fact that it contains:

a second plate lying above said first plate and provided with second openings corresponding to the underlying first openings, the lower edge of said second openings projecting and arranged to press the foil against the upper surface of said first plate, »« φ a third plate lying above, carrying below bell-shaped members for sealed insertion into said second openings, an inverted cup-shaped member arranged in each of said bell-shaped members and coaxial with the cans contained in said first openings and having a dimension corresponding to the inner circular edge of the cans, an insert arranged in said cup-shaped member, each cup-shaped member being arranged on a stem sealed and slidably movable in an opening in the base of said cup-shaped member and provided with an axial channel which opens out onto the outside of the cup-shaped member and into the interior of the cup-shaped member,

- means for vertically moving said plates and said bowls independently of each other, and means for supplying compressed air to said axial channel.

At least two cans are preferably arranged in each recess of the tray.

φ φ φφφφ φ φ • · · · ···· φ · • · · · φ

The inserts are preferably made of a resiliently compliant elastomeric material and have a convex lower surface arranged to press the plastic film against the upper end of the cans, with their lowest point being located substantially centrally on the upper side of the cans.

The means for cutting the foil preferably form a lower cutting edge of a bell-shaped member having a closed profile, describing at a short distance therefrom the edge of the first through-holes in the first plate.

The recesses, each containing at least two cans, are preferably provided with dividing partitions which extend upwards from their base and occupy the free space between the cans, said dividing partitions having substantially the same height as the cylindrical parts of the cans.

The bell-shaped member is preferably provided with one or more thin punching tools for forming, in combination with the upper edge of the dividing partitions, a line of weakened section of the foil which separates each can of the group from the other cans.

The present invention also provides a group of at least two food or beverage cans comprising a single portion of foil corresponding to and covering the surface of the upper portion of the cans forming part of the group, and provided with a line of weakened foil section dividing said portion of foil into several parts, each part comprising a single can of the group.

• · · · • · ··

Overview of images in drawings

The essence of the invention, as well as its structural and functional characteristics, will be explained in more detail below by means of a description of its possible embodiments, which will be given in the form of non-limiting examples, and their description will be given with reference to the attached drawings, where:

Fig. 1 shows a schematic axial sectional view of a device according to the invention;

Fig. 2 to Fig. 6 show on an enlarged scale the detail of Fig. 1 in respective successive and consecutive operating positions;

Fig. 7 shows a sectional view of a package of two cans resulting from the preceding operations;

Fig. 8A and Fig. 8B show different forms of the pressing members 83a;

Fig. 9 and Fig. 10 show individual embodiments relating to cutting a part of the sealing foil adhered to the cans for the purpose of its subsequent separation;

Fig. 12 is a sectional view taken along line XII-XII of Fig. 11;

Fig. 13 shows a schematic axial sectional view of another embodiment of the present invention;

φφ • φ φ φ

φφ ·· φ • · φ • · φ φ • φφφφφ • φ φ • φ φ φ • φ · φ • · φ φ Fig. 14 shows a sectional view, the section being taken along the line XIV-XIV of Fig. 13, of a different operating position;

Fig. 15 shows an exploded view corresponding to the view of Fig. 14.

Examples of embodiments of the invention

The device and the corresponding method for closing or capping cans in groups of two will be described in more detail below with reference to the illustrations according to Fig. 1 to Fig. 7.

With the appropriate, quite obvious adaptations, the device and method according to the invention can also be used for individual cans or for groups of cans consisting of more than two cans.

The can, which is indicated by the reference numeral 4 in the individual figures of the drawings, is of a commonly known type. It usually comprises an upper part 411 formed from a substantially flat upper end 412 of the can 4, its upper neck 413 in the shape of a frustocone and a circular edge 414 which connects the flat upper end 412 to the neck 413 (see in particular Fig. 7). At the upper end there is arranged a tear-off opening, provided with a tab 415, through which the beverage is poured.

The subject device comprises a conveyor belt 1, driven to move in a stepwise manner, on which «· ·· ♦· · ·· ..

• · · · ··· **·· ··· ·♦·· ·«·· • · · · · · · ·*·· · · * . ₍ on the conveyor belt 1, trays 2 are placed one after the other at equal distances from each other. These trays 2 comprise a base with uniformly spaced recesses 3, each arranged to receive a group of cans 4_ (which in the figures consists of two cans £) which are to be processed to form a package.

More precisely, each recess 3 represents, in plan view, the shape of an envelope (or a circumscription) of a group of cans _4, with dividing partitions 31 projecting upward from their base, occupying the space between one and the other can 4_, which would otherwise remain free.

The conveyor belt 1 carries the trays 2 to the processing station, where it is supported by an underlying support surface 11.

Above this processing station is located a first vertically movable plate 6, which in plan view has the same shape as the bowl 2 lying underneath it, and which is provided with through-holes 61, which correspond to the recesses 3, and which have the same shape as these recesses 3.

Alternatively, said plate 6 may be fixed, while the conveyor part carrying the bowl 2 may be vertically movable in order to lift the bowl 2 upwards under the plate 6.

The plate 6, which will be referred to as the reverse centering plate, is provided with a channel 62 connecting the through holes 61 to a vacuum or negative pressure vessel or a vacuum pump, neither of which is shown, and is further provided with a large number of pneumatic sealing inserts 63, ·· φφ φφ φφφφ φφφ · φφφ φφφφ · • φ φφφ φ φφφφ φ · φ φ · φ φ φ φ φ ······ φφ φ ·· positioned on the lower surface 65 of the plate 6 so as to project downwardly to surround the lower edge of the through holes 61.

A thin steel plate Ί_ is attached to the plate 6 and covers its upper surface. This thin steel plate 7_ is perforated like the plate 6 and is provided with hardened sleeves 71, each ^of which is positioned to surround a respective through-hole 61 which passes through both the plate 6 and the plate 7. These through-holes 61 are each arranged to receive, with a certain slight clearance, the upper part of a group of cans y arranged in the tray 2 lying below them.

Above the plate 6 and above the upper part 411 of the cans 4, but below the grid or grate 81, passes a strip of indefinite length of foil 91 of a thermoformable plastic material of a type suitable for food products, such as HiPS, PP, PET, PVC, PE or PS.

Above the first plate 6 lies a second plate 8^, which is positioned above the foil 91, and which is driven by means of a known type (not shown in the figures), as a result of which the foil 91 is pressed against the upper surface of the underlying back centering plate 6.

A grid or grate 81 for pressing the foil 91, movable relative to the plate 8^, is attached to the underside of the plate 8 and, when lowered, rests on a thin steel plate J_. This grid or grate 81 defines a correspondingly large number of openings 84, each of which is arranged to surround φφ «φ φ φ φ φ φ φ φ • · φ φφφ

9999 ΦΦ

Φ Φ Φ Φ φ · * · Φ · « φ 9 «ΦΦΦ φ « ·» _φ • · ΦΦΦΦ • φφφφ corresponding through-hole 61 in plate 6, the lower edge of each hole 84 being arranged to press the foil 91 against the upper surface of plate 6.

Associated with the grid or grate 81 are pressure pressing means acting on the upper part of the foil 91 in order to press this foil 91 downwards until it adheres to the surface of the upper part of the group of cans 4. In the embodiment of the subject matter of the present invention, which is shown in the figures of the drawings, these means comprise axial channels 820 formed in the stems 82 in order to supply compressed air from above downwards, and located through openings 84 above the upper end 412 of the cans 4 (see Fig. 7).

Said stems 82 are vertically movable up and down, the air supplied by said means also impinging, during the first descending part of the stems 82, on that surface of the foil 91 which surrounds the neck of the cans 6, that is to say which comprises the space between one can 4 and another can 4.

Attached to the lower end of the axial channels 820 are respective horizontal discs 83, each of which carries a flat and resiliently compliant pressure member 83a from below (see Figs. 8A and 8B). This pressure member 83a is coaxial with the seats defined by the underlying recesses 3 and the dividing partitions 31 so that each of the horizontal discs 83 is able to descend and exert pressure on the can lid 4.

In the illustrations according to Fig. 8A and Fig. 8B, respective different embodiments of the pressing members 83a are shown.

• « • · • « * 4

4 9

4 4 4

4 4 4 4

4 4 4 444'

These pressing members 83a have a lower convex surface arranged to press the plastic film 91 against the upper end 412 of the cans 4, their lowest point being substantially located in the center of said upper end 412.

As a result of this arrangement, the pressure action of said pressure members starts at the center of the upper end of each can and extends from the center towards the periphery.

Axial channels 820 also pass through the pressure members 83a along their axes and emerge at the center of their bottom surface.

The shafts 82 and the horizontal discs 83 are arranged in the space of through holes 84 which are associated with the through holes 61 in the centering plate 6 lying below them, but which are somewhat wider.

Each of the openings 84 is provided with a downwardly projecting cylindrical blade 85 having a closed profile, circumscribing the edge of the through-openings 61 at a short distance therefrom, said cylindrical blade 85 being adapted to cooperate with the hardened sleeves 71 of the steel plate 11. The cutting edge of said cylindrical blade 85 is continuous in that portion which includes the outer line circumscribing and enclosing the group of cans, but is interrupted along each portion which includes the area between the individual cans where the tear line is formed.

The foil 91, which is unwound from the reel 9, passes through station 5 immediately above the plate 7 and is either rewound • to · • · · · » to · · 1 » to · · · »···· ·· i • · · · « • ·· ··

P · · · · · is wound as waste onto a reel 12, located in the unwinding direction of the foil 91, or is conveyed directly to a grinding device for its immediate crushing.

The tunnel 13 for heating the foil 91 is located between the coil 9 and the station _5.

In another embodiment of the present invention, which is shown in the illustrations according to Fig. 13, Fig. 14 and Fig. 15, a second plate 800 is placed above the first plate 6, provided with protruding edges 801, which have the same shape as the hardened sleeves 71 lying underneath them.

The second plate 800 lies above the foil 91 and is driven by means of a generally known type (not shown in the figures), which causes the foil 91 to be pressed against the upper surface of the underlying back centering plate 6, and in particular against the hardened sleeves 71.

The projecting edges 801 of the second plate 800 define a corresponding plurality of second holes 802 that correspond to the first holes 61 in the first plate 6.

Associated with the second plate 800 are pressing means acting on the upper side of the foil 91 for the purpose of pressing this foil 91 downwards until it adheres to the surface area of the upper end of the group of cans 4.

These pressure means comprise a third plate 80 which, for each group of underlying cans 4, is provided from below with a bell-shaped member 840 with a lower cutting edge.

Both this bell-shaped member 840 and the third plate 80 are provided with through holes, in each of which a stem 821, provided with an axial channel 820, is sealed, the sealing between this stem 821, the third plate 80 and the bell-shaped member 840 being carried out by means of a sealing O-ring 825, which is placed in a recess in the third plate 80.

At the base of each stem 821 is arranged a bowl 822, the lower edge of which can be placed with an exact fit into the flared circular edge 414 of each can 4. This bowl 822 is provided with an insert 823 of deformable elastomeric material, the lower surface of which is convex downwards.

The purpose of said insert 823 is to press the foil 91 onto the lid of the can _4 over the entire area circumscribed by the flared circular edge 414, so that it is subjected to deformation to such an extent that it occupies substantially the entire space in the bowl 822.

Due to the convex shape of the base of the insert 823, its pressure action begins at the center of the upper end of each can £ and extends from this center towards the periphery.

The axial channel 820 opens into four radial openings 824, which are arranged in the shaft 821 immediately above the bowl 822, and through which compressed air can be supplied to the bell-shaped member 840. Said third plate 80 and said shafts 821 can move vertically up and down by means independent of each other, which are not shown in the figures.

The cutting edge of the bell-shaped member 840 has a closed profile which describes at a short distance therefrom the edge of the through-holes 61 for the purpose of interacting with the hardened sleeves 71 of the steel plate 2.

The cutting edge of the bell-shaped member 840 is continuous along that portion which includes the outer line surrounding and circumscribing the group of cans 4, and may be associated with a punch located within the bowl 822 to act on the upper edges of the dividers 31 to form a tear line.

The bell-shaped member 840 is designed to sealably enter the holes in the underlying second plate 800 with a precision fit, by means of an annular sealing insert 841, which forms a seal.

The device shown in the illustrations according to Fig. 1 to Fig. 12 operates in the following manner.

At the beginning of each closing or capping cycle, the respective sequence of trays 2, which already contain groups of cans 4 in their recesses 2, is placed on the conveyor belt 1.

• · • · • · · · · ·

The movement of the conveyor belt JL is intermittent and is controlled so that it always stops when the bowl 2 is positioned in the station such that its recesses _3 are always perfectly aligned with the through holes 61 in the centering plate 6 lying above.

When the conveyor belt 1 stops, the first vertically movable plate 6 descends until it rests in a sealed manner due to the pneumatic sealing inserts 63 on the upper surface of the underlying tray 2, as shown in the illustration according to Fig. 2.

Alternatively, as already mentioned, the support surface 11 then lifts a portion of the conveyor belt JL so that the bowl 2 moves against the underlying fixed plate 6.

After a certain period of time, the foil 91 is heated in the tunnel 13 and immediately thereafter is moved and positioned so that it overlaps the back centering plate 6. Preferably, the heating means in the tunnel 13 may be of the infrared type, and may heat the relevant part of the foil 91 to a temperature of between 120° C. and 230° C., depending on the type of polymer concerned.

At this point, the foil pressing grid or grid 81 is lowered from the plate 8 to stretch the foil 91 spread over the can heads 4 which protrude above the plate 1 on the plate 6, as shown in the illustration of FIG. 3.

• · φ · φφφ φ · · · • ΦΦΦ » · · · · · · φ φ · · · · · φ ·· · φ · φφφ φ φφφφ φ φ · · · • ΦΦ φφφ φφφφ •ΦΦΦΦΦ φφ · ·· ··

After the grid or grate 81 is lowered, the stems 82 are also lowered, while compressed air is simultaneously supplied through the axial channels 820. This compressed air acts on the underlying foil 91 and presses it downwards, as a result of which the foil 91 adheres tightly to the surface area of the upper part of the cans .4.

The compressed air also presses downwards that part of the foil 91 which lies between the two cans 4.

This pressing action is followed by pressure exerted by the pressing members 83 and directed towards the flat upper end 412 of the cans 4.

At the same time, the lower edge of the grid or grate 81 presses the foil 91 against the upper surface of the plate 7_ to form a circular sealing strip through which compressed air cannot pass. As a result, an intermediate space (or chamber) is formed between the foil 91 and the outer surface of the can £, which is isolated from the external environment, at each through-hole 61. Specifically, this intermediate space or chamber is defined by the portion of the foil 91 surrounded by the lower edge of the grid or grate 81, the inner surface of the through-hole 61, the surface of the recess 3 and the outer surface of the can £.

At this stage, the air present in said interspace is sucked out through the channel 62, with the result that the part of the foil 91 which is surrounded by the grid or grate 81 adheres, as a result of this downward suction, to the upper part 411 of the can 4, thus forming a lid which is already attached to the rest of the foil 91, fitting exactly to the shape of the upper part 411 of the can ý.

In an alternative embodiment of the present invention, no suction is created under the foil 91, as its adhesion to the top 411 of the can 4 is achieved solely by air pressure leaving the axial channels 820.

In the following stage (see Fig. 5) the cylindrical blades 85 are lowered in order to make, in combination with the upper edge of the openings 61, a corresponding circular closed cut in the foil 91. This cut is made along a closed line surrounding the envelope of the upper parts of the cans, in order to separate that part of the foil 91 (lids 91a) which is adhered to the group of cans _4, from the rest of the foil 91.

In the embodiment of the present invention shown in the illustration of FIG. 5, the cylindrical blade 85 rests on the upper surface of the hardened bushings 71.

If the foil 91 is substantially rigid, then it is preferred that the cylindrical blade 85 enter the hardened housing 71 with an exact fit and gently contact the inner edge of the upper edge 61a of the through-hole 61, so that it would essentially act like a pair of scissors.

At the end of the entire cycle, all the devices return to their initial position, as shown in the illustration according to Fig. 6. After cooling, the lid 91a then maintains the perfectly φφφ adhered shape that it has taken on the upper part of the can 4, and it maintains this shape even now, so that the cans _4, arranged in each recess 3 of the tray 2, are interconnected by the closing part of the foil 91, which surrounds their upper part (see Fig. 7). In addition, the lid 91a is adhered to the surface of the can _4 by the action of the vacuum, so that it covers the upper surface of the can hermetically, reliably protecting it from contamination from the outside.

It is quite obvious that the trays 2 and the plates 6 will be suitably shaped in plan view to form packages with the required number of cans 4, as shown for example in the illustrations according to Fig. 9 and according to Fig. 10.

The illustrations of Fig. 11 and Fig. 12 show much more clearly the closing or capping of a group of two or more cans 4.

In this embodiment, the recesses 3, each of which contains a group of at least two cans 4, and in particular four cans 5, as in the exemplary embodiment shown, are shaped so that from their base, as already mentioned, dividing partitions 31 protrude upwards, occupying the space that would otherwise remain free between the cans 4.

These dividing partitions 31 have a height which is at least equal to the height of the cylindrical part of the cans 11.

In addition to the cutting means 85 for cutting the foil 91, the illustrated device includes one or more thin • · · · • · · · · · · « • · · · · · · · · ·» • ·

Said line of weakening is shown in the figures of Fig. 9 and Fig. 10 by reference number L2 and in combination with a cut line (indicated by reference number L1, said cut line L1 separating the lid portion 91a from the remainder of the foil 91) surrounds each individual can 4.

Said line L2 of weakened cross-section may consist of a close sequence of small holes or short notches, spaced apart from each other, or of a more or less continuous weakening cut which, however, does not cut through the entire cross-section of the thickness of the foil 91.

The thin punch or perforator 88 consists in particular of a blade, the cutting edge of which is toothed or provided with a corresponding sequence of needles. In addition, the line L2 of weakened cross-section is formed simultaneously with the cutting line L1, by simultaneously lowering the blades 85 and the punches or perforators 88.

A group of two or more cans 4 is thus obtained (see Fig. 9 and Fig. 10) which is provided with a single overlapping foil portion 91a which is flush with the surface area of the upper part and overlaps this surface of those cans _4 which are part of the group. However, the line L2 of weakened section divides said overlapping foil portion 91a into several mutually separate sub-parts, each of which belongs to and is associated with a single can _4.

• φ « · φ · •· Φ ·· • · » · «·«· • ···· «ΦΦΦ • Φ Φ φ φ · Β < Φ Φ * Φ Φ

As a result, a single can 4 can be separated from the group by simply pulling it by hand, so that the overlapping foil portion 91a tears along the line L2 of the weakened section. The can 4_, separated from the other cans 4, retains the respective minor portion of the foil 91 adhering to its upper part, so that it continues to act as a protective lid.

In the modifications shown in Figs. 13 to 15, the stems 821 are first lowered so that the cups 802 begin to fit snugly into the circular rim 414 of the can 4, while the inserts 823 begin to press the foil 91 against the upper surface of the can 4 from the center, thereby expelling air at the periphery.

The edge of the bowl comes into contact with the groove defined by the flared edge only when the air has been completely expelled through the insert, in order to prevent the formation of air pockets near said edge.

At this point, the second plate 800 is lowered so that, by means of its projecting edges 801, the taut film is spread over the projecting can heads £ and against the plate 7 on the plate 6, as shown in Fig. 13, in order to form, in cooperation with the plate Ί_, an endless sealing strip through which air cannot pass.

When the arrangement shown in Fig. 13 is achieved, ·· ·· *· ·· ·♦ ···· 9 4 4 ··«·

9 9 9 9 4 9 9 4 9 9

444 9 4444 4 9 ·· 9

4 9 9 9 4 4 4 9 4 compressed air through radial holes 824 in the shaft 821.

In this way, the chamber is pressurized, which is defined by the bell-shaped member 840, the sealing O-ring 825, the edges 801 of the second plate 800 and the part of the foil 91 that is circumscribed by said edges 801. The pressure acts on the part of the underlying foil 91 outside the circular edge 414 and presses it downwards, causing it to adhere tightly to the surface area of the upper part of the can neck 4.

The pressure generated by the bell-shaped member 840 also presses downwardly the portion of the foil 91 between the cans 4 when it lies at or near the upper edge of the dividers 31.

In the following stage, the third plate 80 is then lowered together with the bell-shaped member 840, the cutting edge of which, in cooperation with the upper edge of the through-hole 61, creates a corresponding circular or endless cut in the foil 91.

This cut is made along a closed line that surrounds the envelope of the can tops in order to separate that portion of the foil 91 that has adhered to the group of cans £ from the remainder of the foil 91.

In the embodiment shown in FIG. 13 , the cutting edge of the bell-shaped member 840 enters the housing 71 with an exact fit, so that these components function essentially as scissors.

• · · · • *

• ΦΦΦ 9

9 9 9

Φ Φ 9 9 9

9 9 9 φ

• Φ • Φ • Φ

In combination with the edge of the bell-shaped member 840, optional punches may also act, which, in cooperation with the upper edges or edges of the dividing partitions 31, create tear lines between the respective cans £.

After the cycle is completed, all components of the device in question return to their initial position.

After cooling due to contact with the cold surface of the can, the foil 91 solidifies and adheres perfectly to the upper part of the cans 4, whereupon it constantly retains this shape.

The cans arranged in each recess 3 of the tray 2 are interconnected by a portion of foil 91 which surrounds their upper parts.

It is quite obvious that the trays 2 and the plates 6, 80 and 800 will be suitably shaped in their plan view in order to form packages with the required number of cans.

Using the described and illustrated device, groups of cans can be formed into packages without interrupting their production process, simply by inserting the device into the production line.

This represents one of the basic objectives of the subject matter of the present invention, which, after being inserted into the production line, eliminates the need to remove the products for packaging purposes and for further handling, which represents a great advantage in terms of production costs.

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It should also be noted here that with the help of one and the same device, cans of different heights but of the same cross-sections can be packed into packages by simply adjusting the distance between the conveyor belt 1 and the combination of plates 6, 8 and 800 together with their accessories.

Claims (12)

PATENT CLAIMS 1. A method of closing packaging cans (4), the upper part of which is formed by a substantially flat upper end of the can (4), its neck (413) in the shape of a frustocone and a circular rim (414) connecting the flat upper end (412) to the neck (413), comprising the steps of placing a portion of a foil (91) of thermoformable plastic material on the upper part of the can (4) in contact with the upper edge of its rim (414) to define a closed chamber in combination with said upper edge of the rim (414), heating the foil (91) to a suitable temperature so that it can meet the conditions of thermoformability, removing air from said chamber, wherein the foil (91) after cooling and solidifying then adheres tightly to the surface of the flat upper end (412) of the can (4) which overlaps and maintains its shape, characterized in that the air is removed from said chamber by means of a pressing action, produced by a stream of compressed air acting on the top of the belt, covering the top of the cans. 2. A method according to claim 1, characterized in that the pressure action exerted by means of a stream of compressed air is carried out in combination with a pressure action limited to the area bounded by the circular edge of the can (4) and carried out by means of a flexible elastic insert (83a, 823). • · ···· • · ·· yyyy 9 9 9 9 · · • ♦ · · · • · · ♦ · · 9 9 9 9 9 9999 99 99 99 99 9 9 9 9 9 9 9 9 9 9 9 9 9 • 9 · · 9 9 99 99 3. A method according to claim 2, characterized in that the action of the flexible insert is carried out in combination with the action of the edge of a rigid cup (822) containing the insert (823). 4. The method according to claim 3 characterize feels t í m , that action inserts (823) are performs before by the action of the edge fixed bowls (822) . 5. Method according to claim 2 characterize feels t í m , that pressure action, exerted by means of a flexible elastic insert (823), is carried out before the pressing action exerted by means of compressed air. action, starting from to the circumference, 6. A method according to claim 1, characterized in that the pressure exerted by the insert (823, 83a) is directed towards the center of the can lid and extends in a direction defined by the circular edge (414). 7. A method according to claim 1, characterized in that the portions of the foil (91) adhering to the top of the cans are separated by cutting along a closed line (L1) located on the frustoconical neck (413) of each individual can (4). 8. The method according to claim 1, characterized in that the film parts (91), by this ·· ·· this · ·* ·* 9 9 9· 9 9 · · 9 9 9 9 9 9 9 9 9 9 9 9 9 · 9 9 9 9 9 9 9999 · 9 99 9 9 9 9 9 9 9 9 9 9 9 9999 99 99 9 99 9· adhering to the upper part of the cans (4), are separated by cutting along a closed line (LI) which closely encloses the outer edge of the line, forming an envelope of said upper part of at least two cans (4). 9. A device for closing packaging cans arranged in recesses (3) of trays (2), comprising an overlapping first centering plate (6) provided with a plurality of first through-holes (61) corresponding to the underlying recess (3) for receiving the upper part of the cans (4) so that they protrude above the upper surface of the centering plate (6), means (9, 12) for placing a heated strip (9) of plastic material over the protruding upper part of the cans, means for ensuring adhesion of said strip to the upper part of said cans (4) and means (85) for separating that part of the strip which adheres to the upper part of the cans (4) from the rest of the strip, characterised in that it comprises: - a second plate (8, 800) lying above said first plate and provided with second openings (84, 802) corresponding to the underlying first openings (61), the lower edge (801) of said second openings projecting and arranged to press the foil against the upper surface of said first plate (6), a third plate (80) lying above, carrying below thereon bell-shaped members (840) for sealingly inserting into said second openings (802), «· ·· ** « ·♦ ·♦ t 9 9 9 4 · · 9 4 4 4 4 4 9 4 4 4 9 4 4 9 4 9 9 444 4 9499 9 9 44 4 4 4 4 4 4 9 4 4 4 4 9444 94 44 · ·9 44 an inverted cup member (822) arranged in each of said bell-shaped members (840) and coaxial with the cans (4) contained in said first openings and having a dimension corresponding to the inner circular edge (414) of the cans (4), an insert (823) arranged in said cup member (822), each cup member (822) being arranged on a stem (821) sealed and slidably movable in an opening in the base of said bell-shaped member (840) and provided with an axial channel (820) which opens to the outside of the cup member and into the interior of the bell-shaped member (840), - means for vertically moving said plates and said bowls independently of each other, and - means for supplying compressed air to said axial channel. 10. Equipment according to claim 9 characteristic with thus that in each recess (3) bowl (2) I am arranged at least two cans (4). 11. Equipment according to claim 9 characteristic with thus that inserts I am made of a flexible elastomeric material and having a convex lower surface arranged for pressing the plastic film onto » φ ·* φ« φ φ · ♦ φ « φφφ φ φ « φφφφφ · φ φφ < φ φ φ φ · « ► φ ·· φφ • · • · φφφφ φφ the top end of the cans, with their lowest point being located substantially in the center on the top side of the cans. claim funds for (840) 12. Device according to, characterized in that the foil cutting is formed by the lower cutting edge of a bell-shaped member having a closed profile, describing at a short distance therefrom the edge of the first through-holes (61) in the first plate (6). 13. The device according to claim 10, characterized in that the recesses, each containing at least two cans, are provided with dividing partitions (31) which extend upwards from their base and occupy the free space between the cans, said dividing partitions (31) having substantially the same height as the cylindrical parts of the cans. according to the invention, by providing one line (L2) of the foil which separates each can from the other cans. 14. A device characterized by a bell-shaped shape is claim 13 member (840) or more thin combination with the upper weakened cross-section to from the group from 15. A group of at least two food or beverage cans comprising a single portion of foil corresponding to and covering the surface of the top of the cans forming part of the group, characterized in that