EP2643221B1

EP2643221B1 - A machine and system for applying container carriers to containers

Info

Publication number: EP2643221B1
Application number: EP11791038.0A
Authority: EP
Inventors: Stephen Paul Bates
Original assignee: British Polythene Ltd
Current assignee: British Polythene Ltd
Priority date: 2010-11-23
Filing date: 2011-11-23
Publication date: 2016-10-19
Anticipated expiration: 2031-11-23
Also published as: GB201019848D0; GB2485895A; CA2815744A1; WO2012069834A1; GB2485895B; GB201120245D0; EP2643221A1; BR112013012591B1; BR112013012591A2; PL2643221T3; DK2643221T3; BR112013012591B8; CN103221309A; ES2610361T3; PT2643221T; US20130263557A1; CN103221309B

Description

Field of the Invention

The present invention relates to a method and machine for applying container carriers to containers. This disclosure also pertains to a flexible carrier stock for machine application to substantially identical containers such as beverage cans having annular chimes, cylindrical side walls, and frusto-conical walls between the chimes and the side walls, and bottles with a neck ridge or seal beading. In particular, the present disclosure relates to the machine application of a plastics film having apertures to securely retain drinks cans, food cans, bottles and similar containers, a unique method of applying the film to the containers, the resultant combination providing a multi-package or unitised pack.

Background to the Invention

It is common practice to package beverages such as sparkling fruit juices, cola drinks, beers and the like in cans, typically being manufactured from pressed aluminium or plated steel, the thickness being of the order of 50 µm or so. These cans are typically sold in four (2 x 2) - or six (3 x 2) packs. Early examples of packaging such packs utilised cardboard which enveloped the cans. In the 1950's plastics film container carriers were first promulgated. The early forms of plastics film container carrier utilised apertures which were deformed upon application of the sheet over the cans, whereby the film formed a continuous flange area about the side of the can. The films were placed about the top of the can, underneath a beaded edge formed at the junction of the lid of the can. Such early forms of carrier film allowed the cans to be pulled through - albeit with some difficulty - but a reverse movement of the can with respect to the carrier would mean that the plastics flange would abut the bead and further movement required a considerable force to release the can.
Figure 1 shows an example from US 2 874 835 (ITW) which provides a carrier 30 comprising a flat sheet of plastics material which is provided with a plurality of apertures 32. The apertures are distinctly smaller (>20%) than a diameter of a can retained by the carrier. Figure 1 a shows how cans, in use are retained, with the circumferential inner edge of the plastics apertures engaging with a lower edge of rim 46. It can be seen that the plastics carrier material is substantially deformed by stretching - after considerable forces have been applied - such that the edge of the aperture is perpendicular to the plane of the plastics carrier period to placement of the cans, especially with reference to feature 40 in Figure 1 b. Indeed, US 2 874 835 indicates that extraordinary force is required for the cans to come loose from the retainer device accidentally. The disclosure of US 2 874 835 indicates that polyethylene is a preferred plastics material, which is stamped in a press to form the apertures. This example taught of additional holes through which the ends of an elongate handle can subsequently be inserted. These plastics films - commonly referred to as carrier stock - are stretched beyond their elastic limit. That is to say the size of aperture will in turn stretch into shapes which are complimentary to the shapes of the container (per US 4 250 682 (ITW)). After a container is removed from the carrier, the carrier cannot be re-used due to the permanent stretching deformation during the application for packaging purposes.
The carrier stock is typically polyethylene and early examples were of a thickness of 500µm or more, although it is typically 400µm or more for rim applied carriers.
The forces necessary to enable the plastics film to engage with the sides of a can were considerable and, of course, the large forces that were utilised to pack the containers together resulted in problems in a consumer accessing an individual can. GB 1 200 807 (ITW) introduced slits in apertures, but forces of application were still considerable since the apertures were "significantly smaller than the diameter of a can with which the carrier film is to be assembled" and therefore were still stretched beyond the elastic limit of the material.
US 2 997 169 taught of a solution to the problem by the inclusion of tear-off tabs 72b; per Figures 2a & 2b, where pre-stressed members associated with tab portion enabled a tear in the plastics retaining film, which was considered easier than forcing the rim of the can around the already stretched plastics film. The cans are of a greater diameter than the apertures and, accordingly, stretch the apertures and deform the material adjacent into a frusto-conical shape whereby the cans are aggressively retained against withdrawal in the direction opposite to that in which they have been inserted.
US 2 936 070 teaches of a still further patent, the teaching of which was to address that a plastics carrier that provides a gripping section not susceptible to loss of a can through twisting and bending movements. With reference to Figures 3a and 3b, resilient, flexible fingers 28 were forced upwardly (as the plastics film is placed upon a number of cans during packing), the fingers being determined by roots 30 defined partway into an inside edge portion of an aperture. Figures 3b and 3c show the teaching from this prior retainer in side views, where the rounded crenulations 28 are clearly visible. US2 936 070 states, in particular, that the root diameter is less than the diameter of the cans and a considerable stretching force is, nonetheless, applied to the plastics material in the vicinity of the roots in stretching the material into the frusto-conical, almost cylindrical conformation shown in Figure 3c. The description further discloses that "the carrier can be assembled with cans with considerable facility, simply by stamping the carrier down over the proper number of cans. The cans simply cam into the apertures, deflecting the fingers....whereby the cans are gripped aggressively with the fingers abutting beneath the can beads". Indeed, the stamping forces would have been considerable.
Further developments included various modifications: one proposal for an article carrier was formed from a tube which was alternately slit from side-to-side in a manner leaving un-slit connecting portions at subsequent alternate opposite sides whereby successive sections of the tube may be folded relative to each other generally into a common plane for receiving the articles to be carried. In order to economize on material, it is generally desirable to make the wall of the tube as thin as possible consistent with the required strength and durability. Thus, in such heretofore proposed structures, immediately adjacent articles in a package are spaced from each other at the area of contact with the carrier only by a double thickness of the relatively thin material. It was found that such spacing is, for many purposes, insufficient since, in practice, the closely adjacent articles such as bottles or cans would rub against each other so that the respective surfaces may be scratched or otherwise defaced. For example, it is common practice to apply a label or other decorative design by lithography or other means to beverage cans and such labelling would be damaged if the cans were permitted to rub together unduly such as when the package was subjected to continual motion or vibration during transport. US 3 924 738 provided a solution to this problem by forming longitudinally extending rib means whereby to provide a separation spacing between cans, as shown in Figure 4.
US 3 968 621 taught of manufacturing a carrier by the formation of an extruded net, which net was subsequently flattened by the use of a roller to produce an apertured film of carrier stock, as shown in Figure 5.
US 3 317 234 teaches of a packaging system using an upper laminate and a lower laminate. As seen with reference to Figures 6a and 6b, the upper laminate comprising a first, continuous plastics layer and a second laminate comprising an apertured card layer is placed over and arrangement of bottles. The apertures of the card layer are arranged to fit over respective metal cap of a drinks bottle, the peripheral edges of the apertures being arranged to engage with the underside of the metal cap, whereby to retain the upper part of the bottle. The lower laminate being arranged to act in a similar fashion with a bottle having a characteristic waist, about which a card member of the second laminate could engage, in conjunction with a plastics layer, which enveloped a lower portion of the bottle. In a similar fashion, cans were retained by substantially similar first and second laminates, the card element of which engaging with a body-directed edge of the respective upper and lower rims of a double rimmed can.
In the early 1980's, there was a shift in the method of applying film stock to cans and the like. Previous forms of strip stock for circularly cylindrical containers had been provided with substantially circular apertures. In contrast teachings equivalent to or derived from US 4 219 117 (ITW), proposed carrier stocks which were designed for application by dedicated jaw and drum machinery (such as described in US 4 250 682 ). These proposals related to stock that had integrally joined band segments defining can receiving apertures in longitudinal rows and transverse ranks. The band segments included generally longitudinal outer segments with each outer segment partly bounding the can receiving apertures in an outer row. The apertures defined in such stock are generally of a triangular/D shape, primarily to assist in the mechanical placement of the stock around the rim of a can, which mechanical application necessitated the use of mechanical fingers which generally prevented the simultaneous use of such devices in any configuration other than in the provision of two-rank longitudinal rows. That is to say the cans are attached with two cans being in a side-by-side arrangement: the systems are limited in use and generally could not reliably operate to provide cans packed, for example in 3x3 or 3x4 or 4x4 etc arrangements.
In the carrier stock illustrated and described in the US 4 219 117 , the band segments also included inner segments partly bounding the can-receiving apertures, along with transversely extending segments joining the inner segments, for finger-hold grip elements.
Can manufacturers have in the past introduced cans having smaller chime diameters, as compared to the diameters of the side walls. Cans of this type are known as "necked-in" cans. The newest versions of these necked-in cans further and drastically reduce the ratio of the chime diameter and the side wall diameter. When stock is applied by known procedures, the band segments defining the can receiving apertures grip the frusto-conical walls of the cans tightly and engage the lower edges of the chimes.
In a necked-in can of a newer type, the frusto-conical wall between the chime and the side wall defines a conical angle greater than approximately 28° and in some instances as great as approximately 37°. When the frusto-conical wall defines such a large angle relative to the can axis, it is difficult to apply carrier stock since the band segments defining the can receiving apertures have an undesirable tendency to slide up the cans and to rest on the cans above the lower edges of the chimes. This tendency is enhanced due to the jaw application system mentioned above.
A further problem of known systems, where great forces have been used to apply the carrier stock, that they can be difficult to remove - not only by accident - in use, especially by youngsters, which has caused effervescent spillage to occur since the removal by force of a drinks can from a carrier strip has resulted in an unnecessary disturbance of the effervescent liquid inside, resulting in a spray or spillage upon a subsequent opening of the can.
EP 0 461 748 (ITW) and EP 0 621 203 (ITW) propose the provision of tear-open tabs, which extend upwardly across the chimes of straight-walled and conical cans, respectively, whereby to simplify release. The tabs in the later patent have concave lateral portions adjacent a stem of the tab "for stress relief". Furthermore, both these documents involve the use of relatively thick (greater than 400µm) carrier stocks which in placement around cans are stretched beyond their elastic limit. These types of carrier stock have not, however, been widely adopted.

Summary of the Invention

The present invention seeks to overcome at least one problem associated with the prior art. Notably the present invention to be particularly described hereinafter seeks to provide a machine and method for grouping and packaging containers such as cans and bottles with a plastics carrier stock sheet comprising film plastics whereby great stretching forces are not required to enable attachment of several containers in a six-pack or similar smaller or larger pack (so-called "unitising" of the containers).
This objective is achievable by use of an application roller configured to urge an appropriate apertured carrier stock sheet film progressively over the rims of successive containers accumulated together for unitizing. The application roller cooperates with the container upper edge (beading, chime or rim) to locate and present an inner edge portion of an aperture of the carrier stock sheet comprising plastics film to the upper edge and progressively move that edge portion below the container upper edge until the whole inner aperture edge becomes located below that container upper edge.
Suitable apertured carrier stock sheet film in various embodiments is subject of our co-pending patent applications GB 2 475 622 A and WO 2011 061 518 .
The terms carrier, carrier stock, carrier sheet and retaining sheet may be used interchangeably herein for ease in describing different aspects of the invention, and refer to a flexible carrier comprising a plastics film suitable for packaging by a method to be more particularly described hereinbelow, notably without requiring use of separating or stretching devices that would in normal use for packaging containers, apply stretching forces that would exceed the elastic deformation limit for the plastics sheet material.
In particular it is notable that the application roller which is adapted for urging the carrier stock upon the accumulated containers according to this invention requires no widening jaws, parting fingers or the like manipulators required in the prior art for stretch-fitting of the carrier to the containers. Rather according to the invention, in handling an apertured carrier or retaining sheet for unitising a plurality of accumulated containers, the roller and accumulated containers are juxtaposed such that as the roller turns relative to the rim of a container, an inner edge portion of an aperture of the apertured carrier sheet engages under the rim at a first point of contact. Thereafter the roller urges the remaining portions of the edge of the aperture to ease over the rim so that progressively the edge portion above the carrier sheet is urged under the rim until the complete aperture edge is below the rim of the container.
In accordance with a first aspect of the invention as defined in claim 1, there is provided machine for applying container carriers to containers by means of a roller.
The configuration of the carrier stock, especially aperture configuration is such that in conjunction with the rolling application method in cooperation with an upper edge of the container e.g. can, the initially flat carrier stock is re-configured to a three dimensional configuration about the can.
The carrier stock forming the container carrier to be applied by the machine comprises a plastics film sheet material having a number of apertures for holding a number of containers together, the apertures arranged in series and extending in at least a first direction, typically the machine direction, for application as a continuous strip from a supply system such as a reel of the aforesaid apertured plastics film. Suitably, the apertures have a centre and edges wherein the edges defining the apertures have a geometry which comprises a plurality of tabs facing the centre, the tabs being separated by troughs, the troughs comprising a root at a maximum point from the centre; wherein the innermost edges of the tabs and the roots lie, respectively, on first and second circumferences relative to the centre, the second circumference being equal to or greater than a beading circumference of a container; the configuration of the apertures being such that, upon placement about a container, the edges of the tabs engage with said beading of such a container as the plastics film about the container is urged downwardly and the plastics film elastically forms a three dimensional wave form structure about the container.
The carrier film is preferably made from the group consisting of polyolefinic plastics such as polyethylene and polyethylene derivatives such as copolymers and addition polymers or polymer blends, but other plastics materials with similar mechanical properties may be used including recycled plastics. The carrier film can be advantageously made from much thinner plastics films, for example of up to about 350µm thickness plastics film. A plastics film of at least about 50 to 75 µm may be used for some containers, and generally a plastics film of up to about 100µm would be suitable for many types of containers. The carrier stock may be made entirely of plastics film for best performance of the invention, but a laminate comprising said film with another material which does not inhibit the flexibility to allow the roller application of the carrier stock over containers as described herein is not excluded. Likewise any coating, labelling, marking, colour layer or applied foil which does not interfere with the rolling application may be used.
The carrier plastics film apertures can be dimensioned to fit around cylindrical walled cans. The carrier plastics film apertures can be dimensioned to fit about reduced chime or necked cans. The carrier plastics film apertures can be dimensioned to fit about beading around the neck of a bottle. Thus the carrier films are apertured to form a container engaging portion for each container to be unitised or multi-packaged. The machine can accept stock comprising a length of a single-rank or multi-rank apertured film.
After such a plastics film is urged over the tops of the containers, it is observed that the formerly flat plastics film conforms partly to the neck or under chime part of the container and otherwise forms a trough so that overall the flat plastics film is converted in the intended use into an undulating surface extending between containers unitised by the film.
The machine also comprises a conveyor system for the transport of containers, which may be of a generally known type; the conveyor being operable to feed the containers to an accumulation position; and taking accumulated containers towards an application station for the application of an apertured carrier or retaining sheet e.g. of the aforesaid carrier stock. The machine uses a roller for urging the apertured carrier or retaining sheet on to the accumulated containers at the application station. The roller receives apertured carrier or retaining sheet from a supply system.
The roller for urging the apertured plastics film onto the accumulated containers may have a modified surface configuration for applying a certain amount of pressure upon the apertured plastics film during or after urging of the apertured plastics film upon the accumulated containers. This may have benefit in ensuring that as the roller moves with respect to successive accumulated containers each aperture is appropriately positioned with respect to a rim of a container such that the edge of the aperture is always urged below the rim of the respective container. In particular the roller may have projections such as mutually spaced pegs or ribs positioned to engage web between apertures of the apertured carrier or retaining sheet of plastics film.
Conveniently, the conveyor and roller are arranged to cooperate together, with the supply system, such that as the conveyor moves the containers, the rims of the containers are presented to the carrier stock of apertured plastics sheet, whereby an inside tab edge of an aperture can abut against an underside edge of a bead of a container. At the same time under the continuing urging motion of the moving roller, the carrier stock of apertured plastics film sheet is urged over the rims of the conveyed accumulated containers. In particular the action of the urging roller in applying the apertured plastics film is such that the side edges of the aperture diverge elastically to surround the sides of the container beading defining a rim of the container until the inside edge of the aperture opposite the first engaged side of the aperture is adjacent the rim. At that point the urging action of the roller causes an inside edge of the said opposite inside tab edge of the aperture to engage with an underside of the rim, whereby to secure the apertured film with the can.
Conveniently, the conveyor moves the containers to an accumulation position prior to being presented to the application station. Conveniently, the conveyor moves the containers with applied plastics film to a cutting apparatus, said cutting apparatus being operable to enable appropriate pack sizes to be produced, whereby separation of unitised container packs is achievable.
Conveniently, there is provided a plurality of co-operating sheeting supply mandrels whereby to provide a continuous supply of sheeting to the roller, to enable a seamless connection of separate sheets to provide effective continuous operation of the system.
In accordance with another aspect of the invention as defined in claim 13, there is provided a method of unitizing containers, for example cans, utilizing the machine and apertured plastics film disclosed herein.
The carrier stock suitable for use in the machine and method of the invention is provided with a number of apertures for holding a number of containers together, the carrier stock comprising a plastics film material having a number of apertures arranged for example as a series in at least a first direction, wherein the apertures comprise a plurality of finger or tab elements, separated by troughs, the apertures having a centre; wherein the innermost edge or tip of the finger elements lie on a first circumference relative to the centre and the bottom of the troughs lie on a second circumference relative to the centre, the second circumference being equal to or greater than the circumference of the container; wherein the edges of the fingers are operably engageable with a beading of a container as the troughs are urged downwardly and outwardly; the troughs being operable to allow the film to elastically deform upon placement and enable the film to adopt a three dimensional structure. Whilst the present invention requires at least three fingers or tabs, it has been found that a four fingered (tabbed) aperture benefits in terms of packaging of product by reason of the forces from the chime, through the finger, allow upward movement of the film adjacent the troughs, whereby to create a wave effect or undulating surface between adjacent containers. The three dimensional structure adopted by the film is analogous in effect to a vehicular monocoque structure; in that the strength of the undulating shaped stock in contact with the containers is greater than that of the otherwise flexible material before it is urged into contact with the containers.
Applicants have determined that at the point where the tabs or fingers meet with the underside of a beading of a container, such as the chime of a beverage can, the material is deflected in a downwards direction. Because the contact is discontinuous, this creates a three dimensional wave in the material which acts against the tabs or fingers and forces them to remain in contact with the containers. At the corners of the sheet (in the case of a four pack for example) opposite where the cut outs in the aperture are situated, because there are no downward forces, only lateral ones exerted by the effect of the fingers acting against the chimes, the material is forced into an apex at its furthest point from the can contributing to the wave effect. This combination of wave effect and apex further prevents the fingers from moving away from the underside of the chime and ensures the containers are held securely.
The apertured material can be dimensioned to fit around traditional cylindrical walled cans such as traditional baked-bean can (say 307 x 512 US CMI). The apertured film can be dimensioned to fit about the necked-in cans as are typically presently produced in the beverage industry (2011) which in Europe is one of the following types (all sizes approximate) 330 ml, 66mm Ø/115mm height; 440 ml, 66mm Ø /150mm height; 500 ml (∼16 fluid ounces US) 65mm Ø / 170mm height.
Another 250ml can size which has been introduced for specialist beverages such as the so-called energy drinks is also slightly necked and is about 52mm Ø / 135mm height.
Due to these dimensional differences in containers to be unitised at different times, the machine of the invention may be equipped with adjustment means for changing the relative positioning of the application roller with respect to the conveyed and accumulated containers between packaging runs of differing containers.
The apertured film can also be dimensioned to fit about the ridge-necked bottles, wherein beading around the neck of a bottle can act in a similar fashion to the chime or beading of a can.
The apertures can resemble a generally square-like (quadra-arcuate) aperture, with the tabs comprising slightly outwardly extending arcs. Other poly-arcuate apertures are possible, the number of tabs, however being less than ten, for containers as are commonly employed for beverages.
The carrier stock comprising plastics film used for the present invention can comprise integrally joined band segments defining can-receiving apertures in longitudinal rows and transverse ranks. There may be a single longitudinal row. The band segments include generally longitudinal outer segments with each outer segment partly bounding the can receiving apertures in an outer row. In application, the carrier stock or film can be provided as a roll for use in a roll on method of applying the product, conveniently in a multi-lane format of typically but not exclusively 6 lanes wide. The sheet material is supplied on a roll and feeds into the application machine in a near continuous action, whereupon it is subdivided within the machine into the required pack sizes, e.g. 4 packs, 6 packs etc.
The method of rolling film on to the top of the container uses the downward pressure of the roller as the containers pass beneath it to gently elastically form the material through the interaction of film and container in order to achieve the aforementioned gripping action and three dimensional transformation of the sheet material. Thus the roller in urging the film onto the accumulated containers to be unitised also has a role in promoting the performance of the film by urging a particular configuration to be adopted.
In particular, the plastics film after application to a number of containers defines a three dimensional shape as a direct result of the various forces acting upon the material, whereby to increase the inherent strength of the resultant product. As a direct result of the increase in strength of the applied film (in three-dimensions), a reduction in the grade and thickness of the film material can be realised: costs can be reduced because less raw material is required. Further by virtue of the machinery not being required to exert tremendous forces to enable the material to engage with containers, the specification of the packaging plant can be reduced, again reducing costs. Overall significant energy savings can be realised by virtue of the invention.
A still further advantage is that because the machinery is less massive and can be applied without large mechanical jaws /hands (as are presently used in the industry - which impede the function of adjacently located mechanical jaws /hands), several packing streams can be simply placed in side-by-side configuration - even enabling 12-aperture rows to be manufactured.
Thus the present invention takes advantage of physical properties of the apertured plastics film material whereby, surprisingly, containers such as beverage cans can be retained by a sheet of a thickness much reduced to the sheet widely employed hitherto which has been placed over the rim of the container, whereby a plurality of inner edges defined along an inner circumference of the aperture abut an underside of the rim, in the free state the inside circumference being less than the circumference of the can, below the rim, the sheet material, by virtue of a discontinuous circumferential contact about said rim, whereby to conform in a three-dimensional form which offers stability and strength to a container and film combination. Specifically, the three-dimensional form provides a strength far greater than that which would have been achievable with a standard film. As a direct result of its increased strength, the material of choice can be selected for price and availability rather than quality per se.
The above and other advantages enable the objectives of the invention to be achieved.

Brief Description of the Figures

Some preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings showing both prior art carrier stock and embodiments of the invention, of which:

Figures 1a - c show a first example of known carrier stock;
Figures 2a, b show a second example of known carrier stock;
Figures 3a - c show a third example of known carrier stock;
Figure 4 shows a container carrier comprising strips of material;
Figure 5 shows another prior art container retaining means;
Figures 6a, b show card and plastics laminate container retaining means;
Figures 7a - e show examples of presently commonly used carrier stock;
Figures 8a - c show a first embodiment of a film and the same in use;
Figure 9 shows a second embodiment;
Figure 10 shows a third embodiment;
Figure 11 shows a still further embodiment of the invention, whilst Figure 11 a shows a variant thereof, and 11 b - 11 d show the variant of Figure 11 a in use;
Figures 12, 12a - 12f detail steps in aspects of the application process;
Figures 13a & b show packaging equipment in plan and side views;
Figure 14 shows a side view of an application drum; and,
Figures 15 - 20 show unitized cans.

Detailed Description of the Preferred Embodiments

There will now be described, by way of example only, the best mode currently contemplated by the inventor for carrying out the present invention. In the following description, numerous specific details are set out in order to provide a complete understanding to the present invention. It will be apparent to those skilled in the art, that the present invention may be put into practice with variations of the specific.

Carrier stock for unitizing containers

The present invention shall now be described with reference to a first embodiment as shown in Figures 8a - c. Figures 8a and 8b show first and second perspective views of an arrangement of five beer cans retained by plastics film stock having six container apertures.
The plastics film is shown in plan view in Figure 8c. Each aperture 80a is of a general square shape, operably arranged to accept a circularly cylindrical part of a container therethrough, with four fingers or tabs 81, 82, 83 & 84 extending from indentations or troughs having a web element connecting adjacent fingers or tabs. The troughs lie on a radius slightly greater than the radius of the container about which the film is designed to retain. The tips of the fingers or tabs, i.e. the portions that will abut the rim or chime of the can, are conveniently slightly curved inwardly. Indeed, in order to most closely fit about a container, the arc corresponds to an arc of a circle of a radius corresponding to a radius of the container that lies immediately adjacent the rim or chime of the container, the shape taking into account the fact that the film will adopt an undulating shape in view of the resilience of the plastics film being utilised. It is important to note that whilst the elastic properties of the film are utilised, the elastic limit of the material is not approached.
In use, carrier stock provided with a number of apertures for holding a number of containers together, the stock comprising a thin plastics film material having a number of apertures arranged in at least a first direction. The apertures comprise a plurality of tab or finger elements, separated by troughs, the apertures having a centre. The tip of the finger elements lie on a first circumference relative to the centre whilst the bottom of the troughs (that part of the troughs most distant from the centre) lie on a second circumference relative to the centre, the second circumference being equal to or greater than the circumference of the container. In use the tips of the fingers engage with a beading of a container whilst the troughs, as a direct result - since they are part of the same film - are urged downwardly and outwardly. In so doing the troughs urge the film to elastically form upon placement and enable the film to adopt a three dimensional structure. Whilst the number of tabs or fingers can vary from three upwards, it has been found that a four fingered aperture (or multiple finger equivalents operable to achieve the same effect) benefits in terms of packaging of product by reason of the forces from the chime, through the finger, allow upward movement of film adjacent the troughs, whereby to create a wave effect. The three dimensional structure adopted by the film is in many ways analogous to the types of structures in vehicular manufacturing i.e. the structure is a monocoque structure where the overall strength of the finished film is greater than that of the inherently flexible material.
Referring in particular to Figure 8c, film 80 is provided with apertures 81, the apertures being defined by fingers 82 - 85. One aperture 81 will now be discussed; the distance between the centres of oppositely facing fingers is approximately 90% of the diameter of the portion of the container about which the aperture will close upon, whilst the distance between opposite troughs corresponds to 110% of said diameter. As can be seen, with further reference to Figures 8a and 8b, the fingers 82 - 85 abut the lower part of the chime or rim of the can and the film closely follows the necked-in portion of the container. Rather than utilising the elasticity of the material to enable containers to be retained, the film as disclosed herein when applied by rolling as described herein adopts a three dimensional geometrical form that enables the shape of the film to thereby provide a relatively rigid arrangement. In actual fact, rather than utilise high quality virgin plastics film of a preferred thickness in the range of 400 - 500µm, the present invention can utilise recycled plastics film of a thickness of about 350µm or even much less e.g. about 100µm or less depending upon the containers to be unitised, with the aim to use as little weight as possible by use of thinner materials. It is to be realised that whilst the weight of a single apertured film for a six-pack is of the order of a couple of grammes, globally, several thousands of tons of plastics are employed in the manufacture of container unitising film. A reduction in the amount of plastics by 25% or more will provide a significant reduction in operating costs for any canning plant. Additionally, it is known in the art (for example EP1038791 ), that any buckling of a transverse web is to be minimised because of customer perception; a smooth transverse web is believed to be more aesthetically pleasing.
As will be appreciated, prior systems for linking containers more closely approach the elastic deformation limit of the plastics material. Indeed, in the apparatus as shown in US-A-4,250,682 a machine is shown which engages a carrier strip and assembles the carrier strip with a plurality of articles moving in close relation thereto. The apparatus in US-4,250,682 has a rotary drum with carrier stretching members for engaging, stretching and positioning the carrier strip over the tops of the articles moving thereunder such that the carrier material is retained under the chime of the article. Similarly, in another teaching ( EP0456357 ) it is stated that a carrier strip engaging assembly is used to elastically deform the engaged carrier strip for assembly with articles.
Since recycled materials are more likely to have inclusions and other faults, which can compromise the strength of material that is stretched towards an elastic limit, the industry has previously not been able to accept such materials, increasing the financial burden in the packaging industry. Not only does the present invention provide a solution which uses less raw material and is according more "environmentally friendly" than prior solutions, the raw material for the present invention can indeed comprise recycled material or at least have a significant recycled material content.

Packaging (unitising) method

The procedure of application of the apertured film in accordance with the present invention can be conveniently formed by a number of methods. A presently preferred method will be described with reference to Figure 8c, which, for convenience shall be assumed to be receiving a can, not shown, from the right; the inside edge of finger 84 of the aperture is urged toward the under-chime (upper rim) of a can; the adjacent side fingers 81, 83 of the aperture are then eased over the corresponding rim parts of the can until the inside edge of the aperture opposite the first engaged side of the aperture is adjacent the rim, whereupon continuing pressure enables the inside edge of the last aperture finger 82 to engage with an underside of the rim, thereby enabling the apertured film to be simply, safely and securely engaged therewith. It will be appreciated that since significant forces would not be required to enable the apertures to be placed over containers, then the machinery need not be so massive and that three or more containers may be easily be retained by a film in accordance with the invention; previous systems cannot reliably utilize more than two containers in a process such as a fast moving production line.
Whilst the first example is a square aperture, it will be appreciated that a generally three fingered aperture may be provided, comprising a generally equilateral triangular configuration, and would provide a minimally fingered design with a security of retention. It will be appreciated that many polygonal forms can be configured which operate in accordance with the disclosed method, although, a regular four-sided aperture is likely to be more readily generally accepted. Containers of other cylindrical shapes can be retained; it may be appropriate to have five, six or more fingers or tabs per aperture. Ten has been found to be a convenient number for large domestic containers.
Referring now to Figure 9, a portion of film 90, with six apertures abreast, is shown, the apertures 91 being of a second regular quadrilateral shape. Further apertures or slits 92, together with circular apertures 93 are sized and positioned to assist in the maintenance of the monocoque film shape, once containers have been retained by the film. The circular opening 93 may be formed of difference shapes or may be replaced by a number of smaller aperture, conveniently closely spaced together. In this film the shape and position of the apertures are such that the troughs between the fingers correspond with the corners of the curved sides, the distance between opposite troughs being approximately 110% the diameter of the container at the rim.
Figure 10 shows a further portion of film 100, which has generally square apertures 101, which have fingers 102 - 105 separated by small troughs 106 - 109. The troughs are move pronounced with respect to the troughs of Figures 9 and 11, but may be of other shapes with regard to a requirement not to induce tears in the film. Again the distance between opposite troughs is approximately 110% the diameter of the container at the rim. Figure 11 shows a still further embodiment, wherein each side of a generally square aperture comprises distinct arc sections 111 - 114; the troughs can be considered to exist at the centre of adjacent arcs 115 - 118. Figure 11 a shows a variant of the arcuate quadrilateral design wherein a substantially square aperture acts with tab elements having an inwardly facing arcuate tab. Figures 11 b - 11 d show the variant of Figure 11 a in use.
A significant advantage of the present invention is that the mechanical properties of the material are only required to be strong enough to hold the cans, and not stand up to the rigours and high stretch of the standard application processes encountered in the prior art. Not only does this have significant advantages in the manufacturing processes (reduced operating forces incur less wear for application machines and thus further reduce operating costs), and also enables the use of cheaper plastics to be employed. Indeed, recycled plastics such as low grade Post Consumer Waste (e.g. low density polyethylene - LDPE) can be employed which also satisfies the perennial demands of market requirements in that the basic consumable materials are cheaper. As discussed above, in view of the materials not needing to be stretched to particular limits, the thickness of the basic product can also be reduced i.e. the thickness can be 300µm (or less): the issue of the presence of inclusions or not is of no consequence. A preferred thickness for such stock for prior systems in an unstressed condition has been in a range from approximately 16 mils (400µm) to approximately 17.5 mils (445µm). The present invention allows the use of raw material that can be purchased at far more favourable rates than specified high quality material.
A preferred method of application utilises a simple roll on application method as shall be disclosed in detail hereinafter; a simple machine can be utilised in manufacturing industry; since great stretching forces are not applied, lever arm and /or hydraulic operations can be minimised and the strength of the machine need not be great, as a direct result compared to systems which stretch plastics towards and beyond their elastic limits. The use of simpler and cheaper machines will also enable the systems to be operated by smaller manufacturing concerns and thereby increase markets.
Figures 12a - 12f show a superposition of the edges of an un-stretched aperture upon a beading 126 of a container 122. Figure 12a shows a first application step associated with retaining a number of containers with a stock of apertured plastics sheeting. An inside tab edge 121 of the aperture abuts against an underside edge of a bead 126 of the container. Figure 12b shows how, in relation to the apertured plastics sheet stock 100 an application roller will rotate with respect to a container passing underneath in a direction perpendicular to the roller axis. The roller is not shown, although the stock is shown having an arcuate profile and will be discussed in greater detail with respect to machinery below.
As the roller continues to move, with reference to Figures 12c & 12d the side edges 123 & 125 of the aperture diverge elastically to surround the sides of the container beading 126. It will be appreciated that this figure is part cross-section in the plane of the beading 126 and part side-perspective view of the can 122. The application forces AF, acting from a centre of the application roller, are relatively gentle - no forces which stretch the plastics sheet material beyond its elastic limit are present. Figures 12e and 12f show corresponding plan and side view of the application process as the edge 127 is received by the rim of the container 126 - as shown, the application roller is shown as the container passes below the axis of the roller.
As discussed above, in view of the reduced forces necessary to assemble containers, system power requirements would be reduced and energy consumption would be reduced. For example, by having the system applying film to containers in 6 - 12 rank widths, then packing stations can be made more compact and simplify distribution since larger widths of format negate a need to divert packs after application ready for tray packing process. A still further advantage in having a wider operating width is that the overall velocity of machinery can be reduced. Compared to a 2-rank packing system, the operating speed is one third to one sixth the speed of such 2-rank packing systems. This will have concomitant advantages in the lifetime, reliability (down-times are expensive) and cost in the conveyor, the motors and supporting equipment. Equally the demands on material would be reduced, also permitting the use of lower grade material.

Packaging plant including unitising machine

With reference to Figures 13a & 13b, there are shown plan and side views of an otherwise standard conveyor system 130 for the transport of containers in the form of soft-drinks cans 139 or similar. In particular, with reference to Figure 13b, the cans 139 are fed along a conveyor to an accumulation position 134 (proceeding in a direction indicated by arrow 138). In the accumulation position, the containers are brought towards each other in close proximity in preparation for the application of the apertured retaining sheet, performed by roller 132 which receives sheet 110 from sheeting supply system 133. Cutting apparatus controlled between the units labelled 136 enable appropriate pack sizes to be produced. With reference to Figure 13b, sheeting supply mandrel 135 can co-operate with another mandrel (not shown) to provide a continuous supply of sheeting to the roller 132. As is known, seamless connection of separate sheets can be performed to provide effective continuous operation, or at least almost continuous operation of the system.
Figure 14 shows, respectively side and detail view of the application drum and production line conveyor arrangement. Figures 16 - 20 show cans unitised with a further example of a carrier stock in accordance with the invention.
The application drum which urges the carrier stock upon the containers to be unitised may have a plurality of peg projections configured to interact with a carrier stock sheet to facilitate appropriate downward pressure upon the carrier stock and assist in elastically forming a three dimensional structure of the carrier stock about the upper part of the containers.
It will be appreciated that, since the containers can be arranged in 6+ wide lines, then different lines may be packaged differently using known techniques, adding variability to the production line process. Additionally, it would be possible, with appropriate channelling, to have cross over with other products (brands) whereby a perceived need for other machines / systems is not necessary. The carrier stock is formed, for example by die-cutting, from a single sheet of resilient polymeric material, such as low density polyethylene. Known carrier stock has been formed of high quality plastics sheet, such as low density polyethylene.

Claims

A machine for applying a container-unitising film to containers by use of a roller (132), the container-unitising film comprising a plastics sheet material (80) having a number of apertures (80a) for holding a number of containers together, the apertures extending in at least a first direction, wherein the apertures have a centre and wherein the edges defining the apertures have a geometry which comprises a plurality of tabs (81-84) facing the centre, the tabs being defined by innermost edges separated by troughs (85-88), the troughs defining a root at a maximum point from the centre; wherein the innermost edges and the roots lie, respectively, on first and second circumferences relative to the centre, the second circumference being equal to or greater than a beading circumference of a container; the configuration of the apertures being such that, upon placement about a container, the innermost edges of the tabs engage with said beading of such a container as the troughs are urged downwardly and outwardly and the apertured sheet material (80) elastically forms a three dimensional structure, wherein the machine comprises a conveyor system (130) for the transport of containers; the conveyor system being operable to feed the containers to an accumulation position (134) and operable to convey the containers towards an application station comprising said roller (132) for the application of the apertured sheet to the containers, the roller in use receiving apertured sheet material from a supply system (133) and urging the apertured sheet material onto the containers such that each container is received in an un-stretched aperture whereby the sheet material forms the three dimensional structure.
A machine according to claim 1 wherein the conveyor and roller are positioned and operable such that as the conveyor moves the containers the rims of the containers are presented to the stock of apertured plastics (Fig.12a,b), and an inside tab edge (121) of the aperture abuts against an underside edge of a bead (126) of the container, and as the roller continues to move (Fig.12c,d), the side edges (123, 125) of the aperture diverge elastically to surround the sides of the container beading (126) until the inside edge of the aperture opposite the first engaged side of the aperture is adjacent the rim and causes an inside edge of the inside tab edge of the aperture to engage with an underside of the rim (Fig.12e,f), whereby to secure the apertured film upon the can.
A machine according to claim 1 or 2, wherein the conveyor moves the containers to an accumulation position (134) prior to being presented to the application station.
A machine according to any one of claims 1 to 3, wherein there is a cutting apparatus, said cutting apparatus being operable to enable appropriate pack sizes to be produced.
A machine according to any one of claims 1 to 4, wherein there is provided a plurality of co-operating sheeting supply mandrels (135) whereby to provide a continuous supply of sheeting to the roller (132), to enable a seamless connection of separate sheets to provide effective continuous operation of the system.
A machine according to any one of claims 1 to 5, wherein the carrier film is made from the group comprising polyethylene, polyethylene derivatives and plastics materials with similar mechanical properties.
A machine according to any one of claims 1 to 6, wherein the carrier film is a plastics film of less than about 350µm thickness.
A machine according to any one of claims 1 to 7, wherein the carrier film apertures are dimensioned to fit around cylindrical walled cans.
A machine according to any one of claims 1 to 7, wherein the carrier film apertures are dimensioned to fit about reduced chime or necked cans.
A machine according to any one of claims 1 to 7, wherein the carrier film apertures are dimensioned to fit about beading around the neck of a bottle.
A machine according to any one of claims 1 to 10, wherein the stock comprises a length of single-rank apertured film.
A machine according to any one of claims 1 to 10, wherein the stock comprises a length of multi-rank apertured film.
A method of unitizing containers, for example cans, utilizing the machine of any one of claims 1 to 12, comprising the steps:
receiving a can;

urging an inside edge of a tab (84) of an aperture toward an under-chime edge of the can;

easing adjacent side tabs (81, 83) of the aperture over the corresponding rim parts of the can until the inside edge of the aperture opposite the first engaged side of the aperture is adjacent the rim; and,

causing an inside edge of the last tab (82) to engage with an underside of the rim, whereby to secure the apertured film with the can wherein the urging of an inside edge of a tab and easing of adjacent side tabs is realised by use of an application roller (132) of the machine which roller cooperates with the container upper edge (beading, chime or rim) to locate and present an inner edge portion of an aperture of the carrier stock sheet film to the upper edge and progressively move that edge portion below the container upper edge until the whole inner aperture edge becomes located below that container upper edge.