GB2588806A

GB2588806A - Automated method of making packaging

Info

Publication number: GB2588806A
Application number: GB1916271.8A
Authority: GB
Inventors: Adam Kearns Jamie
Original assignee: Keco Ltd
Current assignee: Keco Ltd
Priority date: 2019-11-08
Filing date: 2019-11-08
Publication date: 2021-05-12
Also published as: GB201916271D0

Abstract

A method of making a tray from a blank that comprises a base portion 4 with foldable walls 6, 8 comprising section 6”, 8’, 8”. The method comprises the steps of: (a) folding a wall 6, having a projecting tab 12a, along an internal fold line; (b) folding an adjacent wall 8 along an internal fold line and securing at a central portion, preferably using glue 16, but leaving it unsecured at an end to create a pocket; and (c) folding wall 6 generally inwards, such that the tab 12a on the first folded wall is received within the pocket, and securing the projecting tab therein, preferably with glue. Steps (a)-(c) are performed by one or more automated machines. The base may be square or rectangular and the tab may be partially received in the pocket at the end of step (b). Preferably, in step (c) the walls 6 and 8 are simultaneously folded inwards by pushing the partially folded blank into a former cage. A blank and a method of packaging a foodstuff are also claimed.

Description

Title: Automated Method of Making Packaging

Field of the Invention

The present invention relates to a method of making an article of packaging, arid more especially a method of making an article of packaging for a foodstuff. The invention also provides a flat blank of use in performing the method of the invention.

Background of the Invention

Packaging for foodstuffs is well known and may be formed of various materials.

io There has been a significant trend over the last few years away from the use of synthetic plastics materials for use in the packaging of foodstuffs. This is because of the desire to move away from oil-derived synthetic materials, and also because of a desire for packaging materials which are compostable and/or more readily recycled. Accordingly, the use of paperboard, card and paper is especially advantageous.

Another desirable feature of food packaging articles is the ability to form such articles in essentially a fully automated process which can be performed substantially entirely by one or more machines, without requiring human manual input to construct the packaging article, in particular during the final folding or assembly of a partially assembled blank into the finished packaging article.

Whilst paperboard and card materials have many desirable properties, they are not especially strong or rigid. For example, where it is desired to secure a lid to a paperboard tray, the tray walls are not sufficiently rigid for the lid to be securely attached to the tray. GB 2504151 provides one solution to this problem, and discloses a blank which can be folded into a paperboard tray body with side walls having apertures therein, which apertures are engaged by inward projecting protrusions formed on a synthetic plastics lid, the plastics lid being further engaged by folded tabs on the side walls of the tray body, which further engagement acts to secure the lid to the tray body.

However, a significant problem with the arrangement disclosed in GB 25041_51 is that the final step of erecting the folded blank into the finished tray body must be performed by hand. This means that the rate of production of the finished articles is necessarily limited by the rate limiting step in which a human completes the tray body assembly, regardless of any upstream automation of the folding and gluing of the blank An alternative solution is to provide a blank in which, during assembly of the packaging tray, the four walls surrounding the tray base are folded over on themselves, such that the walls are formed of a double thickness of the foldable substrate used as the blank material. However, this type of tray is erected by hand, it) since it is not readily conceivable how to perform the necessary assembly operation by machine.

The present invention aims to provide an essentially fully automated process for making an article of food packaging, especially an article such as a tray. The present us invention also aims to provide a flat blank, and a partially folded blank, which are of use in performing the method of the invention

Summary of the Invention

In a first aspect the invention provides a method of making an article of packaging from a flat blank of foldable substrate, the flat blank comprising a base portion with a plurality of foldable walls foldably attached to the base, each foldable wall comprising an internal fold line, such that each of the foldable walls can be folded over to form a double thickness of substrate along at least part of the length of the wall, the method comprising the steps of (a) folding a first foldable wall, having a projecting tab, along an internal fold line so as to form a first folded wall comprising a double thickness of substrate; (b) folding a second foldable wall, positioned neighbouring the first foldable wall, along an internal fold line so as to form a second folded wall comprising a double thickness of substrate, and securing the two thicknesses at a central portion of the second folded wall whilst leaving the two thicknesses of substrate unsecured to one another at an end portion thereof, thereby creating a pocket in the end portion of the second folded wall, wherein performing steps (a) and (b) produces a partially folded blank, and (c) folding the first folded wall generally inwards, such that the projecting tab on the first folded wall is received within the pocket formed in step (b), and securing the projecting tab therein, thereby producing the article of packaging, wherein steps (a)-(c) are performed by one or more automated machines.

In some embodiments all of steps (a)-(c) are performed on a single automated machine, whilst in other embodiments at least one of the steps is performed on a first automated machine and at least one of the steps is performed on a second, different, automated machine.

Automated folding/gluing machines suitable for use in the method of the invention are available commercially from several manufacturers e.g. Jagenberg AG, Germany; Bobst Group, Switzerland; and Heidelberg Dnickmaschinen AG, Germany. An automated folding machine suitable for performing step (c) is available from Heiber & Schreder Masch nenbau GmbH e.g. the "speedformer" tray-forming machine.

In most embodiments of the invention, the base will be square or rectangular, but other polygonal shaped bases such as triangles, pentagons, hexagons etc can be envisaged. In those embodiments in which the base is square or rectangular, it will be apparent that the blank will comprise four foldable walls, each foldably attached to a respective edge of the base.

In preferred embodiments, the two thicknesses of the substrate of the second folded wall will be unsecured to each other at both the opposed end portions of the second wall, such that in step (b) a pocket is formed at each end of the second wall. The pockets will conveniently be essentially identical mirror images of one another. It is also preferred that the blank comprises a pair of foldable first walls, one on each opposed side of the blank, with the foldable second wall positioned at one end of the blank between, and neighbouring, each of the pair of foldable first walls, the arrangement being such that, in step (c), each of the pair of folded first walls is folded generally inwards, such that a projecting tab on one of the folded first walls is received in the pocket in one end portion of the second folded wall, and a projecting tab on the other of the pair of folded first walls is received in a respective pocket at the opposite end portion of the second folded wall.

More especially, where the base is a square or rectangle, there will preferably be a pair of foldable second walls, one at each end of the blank. The pair of foldable first it) walls are preferably mirror images of one another, and the pair of second foldable walls are preferably mirror images of one another. Desirably, each of the pair of foldable first walls will comprise a projecting tab at each end region thereof, such that, in step (c) a first tab at one end region of a first folded wall will be received within a pocket formed in one of the pair of folded second walls, and a second tab at IS the opposed end region of said first folded wall will be received within a pocket formed in the other of the pair of folded second walls This arrangement is desirably mirrored on the other side of the blank so that, where the base is square or rectangular, there are a total of four projecting tabs (one at each end of each of the pair of folded first walls), each of which will be received in a respective one of four pockets (one at each end of each of the pair of folded second walls). Accordingly, in preferred embodiments, the flat blank will comprise four projecting tabs: one tab at each comer of the blank, which tabs become inserted into a corresponding corner pocket in the manufacture of the packaging article.

In other embodiments, in which the base is not a square or rectangle, there will be a different number of walls. For example, where the base is a hexagon, there will typically be three foldable first walls, and three foldable second walls, with a total of six projecting tabs and six pockets In general, the number of projecting tabs will normally be equal to the number of pockets.

In preferred embodiments, the internal fold line in the first and/or second foldable wall will substantially bisect the wall along its long axis, such that first and second thicknesses of the substrate will overlap over substantially their entire surface. Desirably the internal fold lines present in all of the foldable walls in the blank will bisect the respective foldable walls.

In a preferred embodiment the or each first foldable wall will be divided (preferably, bisected) by the internal fold line, such that the or each first foldable wall comprises a proximal part, which is foldably attached to the base, and a distal part, which is foldably attached to the proximal part. Also, again in a preferred embodiment, the or each second foldable wall will be divided (preferably, bisected) by the internal fold line, such that the or each second foldable wall comprises a proximal part, which is foldably attached to the base, and a distal part, which is foldably attached to the proximal part.

In preferred embodiments of the invention, the or each first foldable wall comprises proximal and distal parts which are of substantially similar shape and size, such that performance of step (a) creates a first folded wall in which the double thickness of substrate (formed by the overlap of the proximal and distal parts) extends over substantially the entire first folded wall. Equally, the or each second foldable wall preferably comprises proximal and distal parts which are of substantially similar shape and size, such that performance of step (b) creates a second folded wall in which the double thickness of substrate (formed by the overlap of the proximal and distal parts of the second foldable wall) extends over substantially the entire second folded wall.

The projecting tab is preferably foldably attached to the distal half of the first foldable wall.

It is also preferred that the double thickness of substrate in the first and second folded walls will extend over substantially the entire length of the walls at least along a top edge thereof Advantageously, all of the folded walls which are present in the finished article of packaging will have a double thickness of substrate which extends over substantially the entire length of the walls, at least along a top edge thereof In step (a), it is highly preferred that the first folded wall is secured by securing means. A convenient securing means is the use of a glue, adhesive or the like. A preferred glue is a cold melt glue such as a water-based glue or PVA/PVC glue, but other glues could be used. For example, if it is not intended to subject the package and the packaged contents to heating, it would be possible to use a hot melt glue. Such hot melt glues are not suitable if it is intended to heat the package in a thermal or microwave oven, as the elevated temperatures would cause the glue to melt and allow the package to unfold.

io Referring again to step (a) of the method of the invention, it is thus preferred that, before folding the first foldable wall, a glue or adhesive is applied to the proximal and/or distal parts of the wall (i.e. on one or both sides of the internal fold line in the first foldable wall). This can be achieved by passing the blank through a gluing station in an automated folding/gluing machine. Where the blank comprises more Is than one first foldable wall (e.g. a pair of such walls, one on each of the two opposed sides of a square or rectangular base), it is advantageous to apply a glue or adhesive to at least part of each first foldable wall, which can be readily accomplished simultaneously at a suitable gluing station on an automated machine. Conveniently, as the blank advances past the gluing station, a beading of glue or adhesive is applied in a run along the majority of the length of at least one of the parts of the (or each) first foldable wall, such that when the wall is folded it is firmly secured by the glue over substantially its entire length.

Conversely, in step (b) it is important that an end portion, and preferably both opposed end portions, of the second folded wall, are left unsecured (e.g. the two thicknesses of substrate are not glued to each other at the end portions), as explained elsewhere above. Accordingly, in the "securing" part of step (b) it is preferred that glue or adhesive is applied only at a central portion of the proximal and/or distal parts of the second foldable wall. Again, this gluing step can conveniently be performed at a gluing station in an automated folding/gluing machine.

It is a preferred feature of the invention that, in the finished article of packaging, all of the side walls around the periphery of the base are tapered slightly (i.e. they project outwards from the base at a slight angle to the vertical). This means that the finished articles can form a nested stack, which facilitates storage and transport of the packaging articles. The presence of a taper also facilitates manufacture of the articles, as described below.

The "securing" in step (c) conveniently is achieved by the use of a glue or adhesive. It is therefore highly preferred that, before performing step (c), glue or adhesive is applied to the, or each, projecting corner tab in the partially folded blank. When the projecting tabs are inserted into their respective pockets, they are secured therein by io the glue or adhesive.

Preferably, in step (c) both the first folded wall and the second folded wall are folded generally inwards simultaneously. Advantageously, all the first folded walls (e.g. if a pair of such walls is present) and all the second folded walls (e.g. if a pair of such second folded walls is present) are all simultaneously folded generally inwards.

A convenient manner of performing step (c) is to push the partially folded blank into an open-ended "cage" former. The cage typically comprises discontinuous walls e.g. formed by discrete metal rods or bars, which define the periphery of the cage.

Desirably the partially folded blank is pushed into the cage by a metal block or punch. This is advantageously dimensioned so as to be slightly smaller than the base part of the blank -this allows the block or punch to exert an even pressure over substantially all of the base part of the blank but, being slightly smaller, the block or punch can be readily withdrawn once the blank has been inserted into the cage. The act of pushing the partially folded blank into the cage forces the first and second folded walls to be folded inwards, substantially simultaneously. Once the partially folded blank has been assembled into the article of packaging the block or punch is retracted from the cage and a subsequent partially folded blank is positioned at the entrance of the cage, ready for the punch or block to push the subsequent partially folded blank into the cage. The partially folded flat blanks are fed into position at the mouth or entrance of the cage by an automated feed. As the articles of packaging are formed, they may form a nested stack inside the cage, with the stack gradually growing and advancing along the cage as each new article of packaging is formed. The nesting is facilitated by the slight tapering of the finished article. In addition, the stack of articles of packaging are kept tightly nested in the cage by the walls of the cage and the action of the punch or block. The tight nesting helps keep the article in the desired shape whilst the glue or adhesive, securing the corners (i.e. the projecting tabs in their respective pockets) is allowed to dry or cure. A number of automated machines suitable for performing this process are commercially available. One example is the CE 1000 tray-forming machine from Heiber & Schroder Maschinenbau GmbH, Germany, which is currently used to manufacture conventional packaging with single-thickness it) walls.

It will be noted that, in step (c) a projecting tab, present on the first folded wall, is received in a pocket in an end portion of the second folded wall. This process is greatly facilitated if, prior to performing step (c), the said projecting tab is brought Is into a position in which it at least partially overlies an end portion of the second foldable wall. Accordingly, it is a highly preferred feature of the invention that, in performing the folding process in step (a), said folding brings the projecting tab on the first folded wall to overlie an end portion of the second foldable wall, prior to performing step (b). It is also highly preferred that performance of step (b) brings part of the second foldable wall to overlie part of the projecting tab, such that part of the projecting tab is sandwiched between the two thicknesses of substrate at the end portion of the second folded wall and partially received within the pocket.

Thus, the projecting tab is already partially received within the pocket created in step (b) at the end portion of the second folded wall, and this directs and facilitates further insertion of the projecting tab into the pocket during step (c). In preferred embodiments, at the end of step (c), substantially all of the projecting tab is received within the pocket and the edges of the first and second folded walls come into abutment at a comer of the article of the packaging In a preferred arrangement, a projecting tab on the distal part of the first foldable wall is brought into a position in which it at least partly overlies the proximal part of the second foldable wall. Preferably the tab does not extend beyond the internal fold line in the second foldable wall, as this might hinder the folding of the blank along that fold line Again, in a preferred arrangement, in step (b) of the method, folding of the second foldable wall along its internal fold line brings the distal part of the second foldable wall into a position in which it at least partly overlies the projecting tab. As described above, this arrangement has the effect of locating the tab within the pocket (formed between the proximal and distal parts of the second foldable wall) before step (c) is performed.

Conveniently the projecting tab is angled slightly, relative to the long axis of the first foldable wall, and wherein the projecting tab may be foldably attached to the first foldable wall by an angled fold line.

The steps of the method generally must be performed in the order stated. However, step (b) could be performed before step (a) It is preferred though that step (a) is performed before step (b) Both steps (a) and (b), in whichever order, must be performed before step (c).

The assembled packaging article is especially suitable, and typically adapted and configured, for use with a lid. The lid is conveniently a separate component, which can be applied to the packaging article once the substance to be packaged (such as a foodstuff) is placed on the base of the packaging article. Lids suitable for use with the packaging article are conventional manufactured components and include, for example, lids made from synthetic plastics materials, which are typically made by a vacuum forming process. The lid will typically be transparent, either wholly or at least over a portion thereof, to permit a prospective consumer to view the contents of the packaging (e.g, prior to purchase).

The foldable substrate will generally be conventional paperboard and the like, which is well-known to those skilled in the art. Typically the paperboard substrate will have a thickness in the region of 200-750jtm, more typically in the range 250-500um. As a result, the double thickness walls may have a substrate thickness in the range 400-1500jim, more typically in the range 500-1000m.

It is also well-known to apply a coating to one or both surfaces of the substrate. The coating will usually be relatively thin e.g. about 50pin in thickness. The precise nature of the coating may depend on the intended purpose of the packaging article, but a common coating is a water-based "Aqueous Coating" varnish or a layer of a film of a substantially water-impermeable material, which renders impermeable the otherwise generally permeable substrate. Such a film may comprise an oil-based synthetic it) plastics material, such as biaxially orientated polypropylene ("BOPP"), polyethylene (PE) or polyester (PET), but biodegradable and compostable laminate films such as polylactic acid (PLA) or cellulose are preferred. Water-based varnishes or coatings are available in a variety of styles (matt, gloss, satin, etc.).

Is Fold lines may be readily created in paperboard substrates using automated machines to introduce folds or creases. The process of introducing fold lines is entirely conventional and well-known to those skilled in the art. The term "fold line" encompasses any line of weakness created in the substrate so as to facilitate folding of the substrate along the line of weakness. The line of weakness may be created by creasing folding, cuts partially through the thickness of the substrate; discontinuous perforations, score lines and the like.

As a consequence of the combination of several features, the method of the invention results in the production of a packaging article which may be used to package liquid or semi-liquid substances. The use of paperboard coated with an impervious film on at least one surface is important, as is the insertion of projecting tabs into pockets at the corners of the package, which helps make the corners essentially leak-proof under normal storage conditions. Finally, the double thickness walls allows a lid to be firmly secured to the walls of the article It may or may not be immediately apparent to those skilled in the art, but in performing step (c), in which the partially-folded flat blank is erected into the article of packaging, there is a choice of orientation from which the flat blank is punched out to form the article of packaging Specifically, in a first orientation the distal parts of the side and end walls come to lie on the exterior surface of the article of packaging, and the proximal parts of the side and end walls come to lie on the interior surface of the article (i.e. that which comes into contact with the substance to be packaged).

However, in the reverse, second, orientation (e.g. if the partially folded blank is fed in it) an automated machine the other way round), then the proximal parts of the side and end walls come to lie on the exterior surface of the finished article of packaging, and the distal parts of the side and end walls come to lie on the interior surface. Each orientation has particular characteristics which may be better suited to particular applications. It is noted that, with conventional hand-erected articles of packaging, only the second orientation can be obtained; the first orientation is thus a unique feature of the method of manufacture of the present invention.

In the first orientation, the interior surface of the article of packaging tends to have corners which are more tightly closed than can be achieved using conventional hand-erect techniques. As a result, the packaging has superior leak-resistance and is especially well-suited to packaging of liquid or semi-liquid substances. However, the exterior surface of the article of packaging has a slightly -untidy" appearance.

Conversely, in the second orientation, the finished article of packaging has only conventional levels of leak-resistance at the corners, but the exterior surface of the packaging is cleaner in appearance and more visually appearing. An article of packaging assembled in the second orientation may therefore be preferred for packaging of dry or solid substances.

In embodiments in which step (c) is performed using an automated tray-forming machine, such as the CE1000 machine from Heiber & Schroder Maschinenbau or similar, the orientation is determined by which side of the base portion of the partly-folded blank is facing towards the cage former, which in turn depends on the orientation of the partly-folded blank in the feed mechanism which positions the blank at the entrance to the cage The partly-folded blanks can readily be fed with the opposite side of the base portion facing towards the cage entrance, in order to produce an article of packaging in the reverse orientation In a second aspect, the invention provides a flat blank of foldable substrate of use in performing the method of the first aspect of the invention, the flat blank comprising a base portion with a plurality of foldable walls foldably attached to the base, each foldable wall comprising an internal fold line, such that each of the foldable walls can io be folded over to form a double thickness of substrate along at least part of the length of the wall, and wherein at least a first foldable wall comprises a projecting tab at one or more end regions thereof, which projecting tab projects outwards beyond the outer edge of the rest of the first foldable wall when the wall is flat and unfolded, but which projects inwards, beyond the inner edge of the foldable wall when the foldable wall is folded inwards along the internal fold line, such that the projecting tab at least partially overlies a second foldable wall which neighbours the first foldable wall Typically the base is square or rectangular shaped and has a foldable wall foldably attached to each edge of the base, the four foldable walls being essentially at right angles to their neighbouring walls.

The size of the article of packaging is not critical. However, the base will typically have sides with a length in the range of 10-25cm, and these constitute a preferred dimension. The height of the walls in the assembled article of packaging may typically be in the range 2-10cm, and this too constitutes a preferred dimension.

Other preferred features of the blank will be apparent from the description of the method of the first aspect of the invention.

In a third aspect, the invention provides a method of packaging a substance, especially a foodstuff or a liquid or semi-liquid substance and, in particular, a liquid or semiliquid foodstuff, the method comprising the steps of making an article of packaging according to the method of the first aspect of the invention; depositing the substance to be packaged onto the base of the article of packaging; and applying a lid to the article of packaging.

The lid is preferably secured to the packaging so as to substantially seal the packaged substance inside the packaging.

The invention will now be further described by way of illustrative example and with reference to the accompanying drawings, in which: io Figures 1-5 are perspective views of sequential stages in a method of folding and gluing an initially flat blank (Figure 1) so as to form a partially assembled blank, which can be erected in an automated way on a machine to provide an assembled article of packaging; Figures 1-4 show the blank in various stages from above, whilst Figure 5 shows the blank, nearly fully assembled, from below; and Figure 6 is a perspective view of the article of packaging from the process illustrated in Figures 1-5

Example

This example relates to a rigid tray or shallow box which may be used as an article of packaging, especially packaging for a foodstuff. The assembled article is illustrated in Figure 6 and comprises a substantially square tray base surrounded by four walls, made up of a pair of identical side walls, and a pair of identical end walls. The square base has sides of about 14cm, and the height of the walls is about 3.7cm. The walls are all angled slightly outwards, away from the tray base, such that a plurality of assembled trays may be provided as a nested stack. Although not readily apparent from Figure 6, each of the end walls and side walls is formed of a double thickness of the foldable substrate material used to make the tray. The tray may be made from an initially flat blank of such foldable substrate, via a substantially fully automated process, by a method in accordance with the invention. Various sequential stages in the performance of the method are illustrated in Figures 1-5. In particular, in going from the stage illustrated in Figure 4 to the fully assembled tray shown in Figure 6, no manual intervention is required.

Referring to Figure 1 there is shown a flat blank 2 of foldable substrate. The substrate comprises paperboard of about 400pm thickness, which is coated on one side with an impermeable polylactide (PL) film. The PL coated side forms the innermost surface in the assembled tray (i.e. that surface in contact with the packaged foodstuff). The coating renders the paperboard substrate substantially impervious to moisture, so that e.g. liquid and semi-liquid foodstuffs may be held within the tray without leaking. The blank is formed from a large sheet or roll of suitable coated substrate material by cutting on an automated cutting machine.

The blank 2 comprises, in the illustrated embodiment, a square tray base 4, with a pair of identical first foldable walls 6 (one at each side of the base 4), and a pair of identical second foldable walls 8, (one at each end of the base 4). Each first foldable wall is formed with an internal fold line or crease 5, and each second foldable wall is formed with an internal fold line or crease 7, which internal fold lines 5, 7 separate the respective walls into a first, proximal, portion 6' or 8', adjacent to the tray base 4, and a second, distal, portion 6" or 8", distal from the tray base 4 The internal fold lines substantially bisect the respective first and second foldable walls along their long axis Each proximal portion 6' of the first foldable walls is foldably attached to the base 4 along respective fold line 13, and each proximal portion 8' of the second foldable walls is foldably attached to the base 4 along respective fold line 15.

Other fold lines or creases 9 and 11 are present, which define projecting corner tabs 10a 10b or 12a 12b on the distal portion 6" of the respective first foldable walls 6, and the significance of these is explained later.

As noted elsewhere, all of the steps described herein in the assembly of the tray are performed on an automated machine As a result, a high rate of production can be obtained, and the finished product can be supplied to the end user fully-assembled, in a compact nested stack.

In Figure 1, the blank is shown such that the surface of the base 4 which is visible in the Figure will form the exterior surface in the completed article of packaging. The blank is folded in step (c) of the method of the invention in the "first"' orientation, which results in the distal parts 6-, 8-of the side and end walls forming the exterior surface of the completed article of packaging, and the proximal parts 6', 8' of the side and end walls forming the interior surface of the article of packaging (i.e. that surface which comes into contact with the substance to be packaged). Those skilled in the art will however appreciate that the blank could be folded in step (c) in the reverse orientation, such that the distal parts 6", 8" could form the interior surface and the io proximal parts 6', 8' could form the exterior surface.

In the illustrated embodiment, a run of glue (e.g. conventional "cold melt" adhesive) 14 is applied to each proximal portion 6' of the first foldable walls, at a gluing station as the blank advances through an automated folding/gluing machine, although the IS glue could additionally, or alternatively, be applied to the distal portion 6".

As illustrated in Figure 2, arms (not shown in the Figure) on the automated machine force the distal wall portions 6" to fold inwards about fold line 5, so as to overlie the respective proximal wall parts 6' and are held in that position by the glue 14. Note that this folding step brings the angled projecting corner tabs 10a, 10b and 12a, 12b inwards, beyond the inner edge of proximal wall portion 6', such that at least a part of each corner tab overlies one or other of the proximal wall portions 8' of the second foldable walls. Prior to the folding step, the projecting corner tabs 10a, 10b and 12, 12b project outwards, beyond the outer edge of their respective distal wall portions 6".

The partially folded blank then advances to a second gluing station in the automated machine. At this gluing station, as shown in Figure 3, a restricted small amount of cold melt glue 16 is applied as a spot or blob solely to a generally central portion of proximal wall parts 8' of each second foldable wall, although the glue could also (or alternatively) be applied to distal wall portions This leaves the opposed end regions of the wall portions 8' and 8" unsecured to each other such that, at the opposed end regions the distal wall portion 8" is able to flex away from proximal wall portion 8' as shown in Figures 4 and 5.

As then shown in Figures 4 and 5, each distal wall portion 8-is folded inwards so as to overlie the respective proximal wall portion 8', and is held in that position by the glue 16 This folding operation is not entirely straightforward, in that the distal wall portion 8" at the rear of the blank must be folded forwards against the direction of travel of the blank through the machine (a so-called "backfole). This is accomplished by a rocker arm, cam or the like which swings downwards to act on the rear end wall from above, forcing the rearmost distal wall portion 8' forwards and downwards, into contact with the glue 16 on the proximal wall portion 8'. As the io blank advances, the rocker arm or cam swings beneath the plane in which the blanks advance through the automated machine, and then rises above the plane as the next blank to be folded advances through the folding station, for the process to be repeated on the next blank and so on.

Importantly, the inward folding of the distal wall portions 8" creates a pocket at each of the corners of the partially folded blank and bring part of the second foldable wall (i.e. the distal wall portions 8") to overlie the projecting corner tabs 10a, 12a and 10b, 12b, as appropriate, such that at least part of the projecting corner tabs is sandwiched between the two thicknesses 8', 8" of substrate at the end portion of the second folded wall, and the tabs are partially received within the corner pockets. As a result, in the next folding step, described below, the projecting tabs are naturally directed and forced inwards further into the corner pockets.

The folding steps accomplished thus far result in the formation of double thickness walls at each end and at each side of the tray base 4.

As also best seen in Figure 4, a spot of glue 18 is applied to each of projecting corner tabs 10a, 10b, 12a and 12b In the next step of the automated process, the glued and partially folded blank is fed into a "cage" on a forming machine. The cage is open at the bottom, to allow the glued and partially folded blank to be fed into the cage from the underside, the blank being punched by a metal block. The sides of the cage are discontinuous and formed by vertical metal bars. Typically three such bars are provided on each side of the cage.

As the partially folded blank is forced into the cage, by the advancing metal block, all the folded side walls and folded end walls 6, 8 are forced generally inwards simultaneously, such that angled corner tabs 10a, 10b and 12a, 12b are fed into the respective pockets formed between the end wall portions 8' and 8". The flexibility of the ends of the wall portion 8" is thus seen as desirable in (a) making a space between the wall portions 8' and 8" sufficient to receive a respective corner tab 10a, b and 12a, b but also (b) creating sufficient clearance between the corner tabs 10a, b and 12a, b and the adjacent wall portion 8", such that the newly applied dots of glue 18 are not brushed off the tabs as they fold into their respective pocket. When the inwards movement of the folded side and end walls is completed, each of the projecting corner tabs 10a,b 12a,b is substantially fully accommodated within its respective pocket.

As noted above the partially folded blank is pushed into the cage by a metal block or punch. This is advantageously dimensioned so as to be slightly smaller than the base part of the blank -this allows the block or punch to exert an even pressure over substantially all of the base part of the blank, but being slightly smaller, the block or punch can be readily withdrawn once the blank has been inserted into the cage. The act of pushing the partially folded blank into the cage forces the first and second folded walls to be folded inwards, substantially simultaneously. Once the partially folded blank has been assembled into the article of packaging, the block or punch is retracted from the cage and a subsequent partially folded blank is positioned at the entrance of the cage, ready for the punch or block to push the subsequent partially folded blank into the cage. A supply of partially folded flat blanks is fed into position at the mouth or entrance to the cage by an automated feed.

As the articles of packaging are formed, they may form a nested stack inside the cage, with the stack gradually growing and advancing along the cage as each new article of packaging is formed The nesting is facilitated by the slight tapering of the finished article.

In addition, the stack of articles of packaging are kept tightly nested in the cage by the walls of the cage and the action of the punch or block. The tight nesting helps keep the article in the desired shape whilst the glue or adhesive, securing the corners (i.e. the projecting tabs in their pocket) is allowed to dry or cure.

The entire process can conveniently be performed entirely using an automated machine. One such commercially available machine suitable for performing this process is the CE 1000 tray-forming machine from Heiber & Schroder Maschinenbau GmbH, Germany.

Claims

Claims 1. A method of making an article of packaging from a flat blank of foldable substrate, the flat blank comprising a base portion with a plurality of foldable walls foldably attached to the base, each foldable wall comprising an internal fold line, such that each of the foldable walls can be folded over to form a double thickness of substrate along at least part of the length of the wall, the method comprising the steps of: (a) folding a first foldable wall, having a projecting tab, along an internal fold io line so as to form a first folded wall comprising a double thickness of substrate, (b) folding a second foldable wall, positioned neighbouring the first foldable wall, along an internal fold line so as to form a second folded wall comprising a double thickness of substrate, and securing the two thicknesses at a central portion of the second folded wall whilst leaving the two thicknesses of substrate unsecured to one another at an end portion thereof, thereby creating a pocket in the end portion of the second folded wall, wherein performing steps (a) and (b) produces a partially folded blank; and (c) folding the first folded wall generally inwards, such that the projecting tab on the first folded wall is received within the pocket formed in step (b), and securing the projecting tab therein, thereby producing the article of packaging; wherein steps (a)-(c) are performed by one or more automated machines.
The method according to claim 1, wherein the base is square or rectangular.
3 The method according to claim 1 or 2, wherein the blank comprises a pair of foldable first walls, and step (a) includes folding each of the pair of foldable first walls along an internal fold line to form a pair of first folded walls.
4. The method according to any one of the preceding claims, wherein the blank comprises a pair of foldable second walls, and step (b) includes folding each of the pair of second foldable walls along an internal fold line to form a pair of second folded walls.
5. The method according to claim 4 as dependent on claim 3, wherein the pair of foldable first walls are a mirror image of one another, and the pair of second foldable walls are a mirror image of one another.
6. The method according to any one of the preceding claims, wherein the internal fold line in the first and/or second foldable wall substantially bisects the first and/or second foldable wall, as appropriate, along its long axis.
7. The method according to each of claims 2, 3 and 4, wherein the partially us folded blank comprises four projecting tabs and four pockets.
8 The method according to any one of the preceding claims wherein, prior to performing step (c), the projecting tab on the first folded wall is already partially received within the pocket formed in step (b).
9. The method according to any one of the preceding claims, wherein performance of step (a) brings the projecting tab on the first foldable wall to overlie an end portion of the second foldable wall.
10. The method according to any one of the preceding claims, wherein performance of step (b) brings part of the second foldable wall to overlie part of the projecting tab, such that part of the projecting tab is sandwiched between the two thicknesses of substrate at the end portion of the second folded wall, and partially received within the pocket
11. The method according to any one of the preceding claims, wherein the projecting tab is joined to the first foldable wall by a fold line which is at angle to the long axis of the first foldable wall.
12. The method according to any one of the preceding claims, wherein step (a) further comprises depositing glue or adhesive to at least part of the first foldable wall before folding, so as to secure the first folded wall in a folded configuration.
13. The method according to any one of the preceding claims, wherein securing in step (b) comprises depositing glue or adhesive to a central portion of the second foldable wall, before folding the wall, whilst leaving the end portions of the second foldable wall devoid of glue or adhesive.
14. The method according to any one of the preceding claims, wherein the first and second folded walls have a double thickness of substrate along substantially their entire length at the top edge thereof Is
15. The method according to any one of the preceding claims wherein, prior to performing step (c), glue or adhesive is applied to the projecting tab, such that the projecting tab is secured by the glue or adhesive within the pocket.
16. The method according to any one of the preceding claims, wherein step (c) comprises folding first and second folded walls generally inwards simultaneously.
17. The method according to claim 16, wherein the first and second folded walls are folded generally inwards simultaneously by pushing the partially folded blank into a former "cage"
18. The method according to any one of the preceding claims, wherein the walls of the assembled article of packaging are tapered, such that the articles may form a nested stack.
19 A flat blank of foldable substrate of use in performing the method of any one of the preceding claims, the flat blank comprising a base portion with a plurality of foldable walls foldably attached to the base, each foldable wall comprising an internal fold line, such that each of the foldable walls can be folded over to form a double thickness of substrate along at least part of the length of the wall, and wherein at least a first foldable wall comprises a projecting tab at one or more end regions thereof, which projecting tab projects outwards beyond the outer edge of the rest of the first foldable wall when the wall is flat, but which projects inwards, beyond the inner edge of the foldable wall when the foldable wall is folded inwards along the internal fold line, such that the projecting tab at least partially overlies a second foldable wall which neighbours the first foldable wall.
20. A method of packaging a substance, especially a foodstuff or a liquid or semi-lo liquid substance and, in particular, a liquid or semi-liquid foodstuff, the method comprising the steps of making an article of packaging according to the method of any one of claims 1-18, depositing the substance to be packaged onto the base of the article of packaging; and applying a lid to the article of packaging