GB2088811A - Producing a succession of individual, e.g. multi-tube, packs - Google Patents

Abstract

In a horizontal form-fill-seal machine, twin-tube packs, for example, can be produced by forming in a moving flexible web (11) two corrugations running in the direction of movement of the web; bringing the opposite edge regions of the web (11) towards one another beneath the corrugations and folding the edge regions against one another to form a fin projecting beneath the centreline of the web; gripping the fin between pairs of contra-rotating rollers which drive it in the direction of movement of the web and which crimp the fin to seal it; sealing the web surfaces between the corrugations together to define twin tubes in the web; and cross-sealing and severing the web at intervals spaced along its length. The two thicknesses of material between the currugations are sealed by nipping them between a heated sealing roller and the face or faces of one or a pair of the contra-rotating rollers which are themselves heated to seal the fin as it passes through their nip. The web may be perforated or separated longitudinally between twin tubes. <IMAGE>

Description

SPECIFICATION Producing a succession of individual multi-tube packs The invention relates to the production of a succession of individual multi-tube packs, and may be embodied in a machine and in a process for producing such packs.

The problem of producing a succession of multi-tube packs arises for example in automatic high speed wrapping of such things as chocolate bars. It is sometimes desirable to produce so called "twin packs" in which elongate and generally tubular chocolate coated bars can be wrapped and sealed side by side of one another rather than being wrapped and sealed as single articles. Machinery which will produce a continuous succession of wrapped filled and sealed single-tube packs of chocolate is already known, and is usually referred to as horizontal form-fill-seal machinery.The attempted production of the so called "twin packs" containing products such as chocolate coated bars brings with it special problems, due partly to the high speed of forming, filling and delivering the packs, and due partly to the care needed in sealing the "twin-packs" around a product which is all too easily affected by sealing adhesives or by the application of heat.

The invention is particularly, although not exclusively, applicable to the producton of "twin packs" of chocolate coated bars, and seeks to overcome the problems just outlined.

In accordance with the invention, a succession of multi-tube packs is produced by forming, in a moving flexible elongate web, corrugations which run parallel with one another in the direction of movement of the web; bringing the opposite edges of the corrugated web towards one another by an amount which leaves at least two corrugations in the web surface but which causes the web edge regions together to span those corrugations; sealing the corrugated surface to the web edge regions, along lines which run along the web and between adjacent corrugations, to form tubes running along the web; and sealing the web surfaces to one another along lines which run across the web and which are spaced at intervals along the web.

A machine producing multi-tube packs in accordance with the invention may incorporate means to perforate the packs, between adjacent tubes and in the direction of movement of the web, so that it is relatively easy for each pack so perforated to be subsequently split longitudinally into two or more single-tube packs.

Instead of simply being perforated, the multitube packs could be positively separated, by cutting longitudinally and between adjacent tubes, as they come off the machine; thus effectively doubling the output of a single-tube-forming and sealing machine driven at the same speed.

The individual multi-tube packs defined between successive cross-seals of the web would normally he separated from the web during, or after, the cross-sealing operation. They could for example be separated by cutting across the web, after the cross-sealing operation, in front of (and parallel with) one cross-seal and behind (and parallel with) the next cross-seal.

Alternatively each cross-seal could be formed by sealing across the web along two parallel lines, each running across the web and spaced apart from one another by a relatively small amount, and cutting across the web between each of the two lines.

Either of the cross-sealing alternatives just outlined would produce individual packs each sealed across both ends. Whatever products the packs contained would have to have been inserted into the web tubes before the cross-sealing and cutting operations were completed. This could be done by feeding the products in parallel streams into the web tubes as the tubes were being formed. In such a process the tubes would effectively be wrapped around the products, sealed longitudinally, and then cross-sealed transversely.

In any of the broad aspects outlined above, the invention provides a means of producing a succession of formed, sealed, and if necessary filled, multi-tube packs (or a doubled output of single-tube packs) from an elongate web moving at a continuous high speed.

One machine embodying the invention is illustrated diagrammatically in the accompanying drawings. It will now be described with reference to those drawings. The machine is a high speed horizontal form-fill-seal machine for producing wrapped "twin packs" of chocolate coated bars.

Figure 1 of the drawings shows diagrammatically the construction and operation of the machine.

The remaining Figures of the drawings show in cross section various parts of the machine, and various alternative forms which certain of those parts might take.

Referring now to the drawings, and initially to Figure 1, the machine contains a succession of stations each of which performs an operation on an elongate flexible web which runs continuously and at a relatively high speed through this succession of machine stations. The stations are generally in line with one another, and the web flows through them horizontally. The first station forms the web into a continuous elongate twintube pack, and wraps it around a succession of chocolate coated bars which are supplied at high speed to the machine and which enter the machine underneath the moving web. The second machine station seals the web tubes longitudinally from one another and simultaneously completes the tube formation by sealing the web edge regions together underneath the tubes. The third station perforates, without separating, the longitudinal seals.Finally the fourth station seals the web surfaces together across the web to define a succession of individual packs each of which is separated from the web as the pack leaves the machine.

The web is referenced 11 in Figure 1. It is made of suitably proofed paper which is flexible and can be heat-sealed. It is drawn from a reel (not shown) and kept in an appropriately tensioned state during its journey fromthe reel through the machine. it has already been pre-printed with desired advertising material to be displayed by the eventually formed packs.

As the web 11 enters the tube-forming station of the machine, it runs under rollers 12 which span only a central region of the web. Because the web is tensioned, its edge regions automatically fold upwards as shown when it passes beneath the rollers 12. The central region of the web enters a gap formed between an upper bar 13 and a lower bar 14. Both bars are elongate and linear, and overlap to define between them a slit 1 5 along which the central region of the web travels.

As shown in Figures 2 and 3, which are respectively sections through the bars 13, 14 at points A-A and B-B in Figure 1, the slit 1 5 guides the central region of the web 11 steadily down to the level of the bed plate 1 6 of the machine. As this happens, the turned-up tensioned opposite edge regions of the web are guided underneath arms 17, 1 8 which project from the bed plate 1 6. The opposite edges of the web are brought towards one another, underneath the bed plate 16, by the web edge regions entering the nip of a first pair of rollers 19.The overall effect is two-fold: firstly, to effectively corrugate the top surface of the paper web 11 into two corrugations disposed one on either side of the bar 13 and extending in the direction of movement of the web; and secondly, to form each of those corrugations into a tube by bringing the opposite edge regions of the web close enough two one another so that the web edge regions span the corrugations as shown in Figure 4 of the drawings.

The succession of chocolate coated bars previously referred to is delivered to the machine by an endless chain conveyor referenced 21 in Figure 1. As shown, this conveyor 21 delivers the bars two at a time and in parallel streams. The bars are indicated by the letter B in the drawings.

They are generally elongate and rectangular, and all have the same basic dimensions. The speed at which the bars arrive is matched to the speed of the incoming web.

As shown, the parallel stream of bar product are delivered one to either side of the elongate bars, 13, 14. The web tubes are formed around the bar products B. The formed web is pulled through the machine by three sets of rollers of which the rollers 1 9 comprise the first set. The rollers of this first set, like the rollers of each of the other sets 22, 23, contra-rotate. Another similarity between all three sets of rollers is that their peripheries are corrugated to crimp the edge regions of the paper web between them as they nip the web during its passage between the rollers. However, the rollers 1 9 are unheated: whereas the rollers 22, 23 are each electrically heated so as to heat-seal the edge regions of the paper web together.

The edge regions of the paper web are crimped, but not heat-sealed, by the first set of rollers 1 9.

As the crimped edge regions enter the second, and heated, set of rollers 22, another roller 24 bears against the top surface of the paper web and presses that top surface down against one of the rollers 22. The roller 24 is free-running, unlike the rollers 19, 22, 23. It is however spring-loaded down onto the surface of one of the rollers 22, and it is heated. It therefore seals the top surface of the web 11 to the bottom surface of the web as shown in Figure 5, sealing along the "valley" between the twin tubes of the web.

Figures 4 and 5 show these operations.

Figure 5 also shows clearly the way in which the line of sealing of the roller 24 is offset from the line along which the edge regions of the web are crimped and sealed by the rollers 1 9, 22, 23.

The rollers 19, 22, 23 are all driven about vertical axes of rotation. Another set of rollers 25 is interposed between the final rollers 23 and the perforating station of the machine. The rollers 25 turn the crimped and sealed edge regions up flat against the bottom of the web, as shown in Figure 6. The web then enters the perforating station where a circular blade 26 is driven about a horizontal axis and co-operates with a similarly horizontally driven circular anvil 27. As shown, the sharpened periphery of the blade 26 is notched at intervals, and the blade thus perforates the sealed "valley" between the two tubes of the web 11 without completely separating the two tubes from one another.

As Figure 6 shows, the line of perforation is again offset from the centre line of the formed "twin pack": but it is still within the area heatsealed by the roller 24.

The longitudinally sealed, filled and perforated continuous "twin pack" emerges from the perforating station and is crimped and heat-sealed across its entire surface by heated contra-rotating cylinders 28, 29. As shown in Figure 1, these heated cylinders each have one portion of their periphery raised out of the peripheral surface, and formed as a crimping bar extending along the cylinder. The speed of contra-rotation of these cylinders 28, 29 is matched to that of the web in such a way that they crimp and heat-seal the web in the longitudinal intervals between successive bars of product B carried by the web tubes. The result is the formation of a succession of individual twin-tube packs each containing two bars B of product.

As the cross-sealed web emerges from the crimping and sealing cylinders 28, 29, the individual packs can then be separated from one another by cutting along the cross-band of crimped sealed material whilst remaining within the opposite edges of that band. The cutting means need not be described in detail, and are not illustrated.

As shown in Figure 1 , the second set of crimping rollers 22 is driven from a main power drive of the machine. The drive for the circular perforating blade 26 is also taken from this main power drive, as illustrated, by way of tensioned chains and sprockets.

Any alterations to the web speed will thus automatically be reflected in the speed of the perforating blade 26.

In the machine illustrated, the roller 24 is not driven. It could however be driven similarly, from the drive to the crimping rollers 22 and the perforating blade 26. It need not necessarily take the form of a roller. It could be a spherical ball bearing, or even a fixed slipper. Although heated, it could be unheated if the properties of the web were such as to generate a sufficiently good heatseal between the heated rollers 22 and the pressure from the unheated roller 24.

Although the roller 24 is illustrated in Figure 5 as being offset from the nip of the rollers 22, it need not necessarily be so. Figure 7 shows an arrangement in which the roller 24 is directly above the nip of the rollers 22. Figure 8 shows one possible form of the resultant seal made by the roller 24, where the area of the web 11 directly above the nip 22 has not been sealed. That unsealed area could be perforated by the blade 26 instead of the blade perforating the sealed area to either side of the unsealed area.

The perforating station could be omitted altogether in circumstances where it was likely that both bar products B would be eaten together once the pack was opened. Alternatively the perforating blade 26 could be replaced by a straight cutting blade, in which case it might be desirable for the crimping and cross-sealing of cylinders 28, 29 to take place before the "twin packs" were cut by the cutting blade.

If the web were made of the so-called "cold seal" material, none of the rollers need be heated, as this material already contains sealant which is pressure-sensitive and will bond the web surfaces together as they are crimped and pressed by the rollers.

Although the machine described and illustrated is a continuous-flow machine, the invention is equally applicable to an intermittent-flow machine.

Claims (12)

1. A machine, or a process, for producing a succession of multi-tube packs by forming, in a moving flexible elongate web, two corrugations which run parallel with one another in the direction of movement of the web; bringing the opposite edges of the web towards one another to cause the web edge regions to span the corrugations; folding the web edge regions against one another to form a double-thickness fin projecting from the general plane of the two thicknesses of material between the corrugations; gripping the fin and driving it in the direction of movement of the web; sealing the said two thicknesses of material between the corrugations together to form two tubes running along the web; and sealing the web surfaces to one another along lines which run across the web and are spaced at intervals along the web.

2. The invention of claim 1 in which the fin is gripped and driven between the respective edges of a pair of contra-rotating rollers, and the two thicknesses of material between the corrugations are sealed by nipping them between a sealing surface and the face of one of the contra-rotating rollers.

3. The invention of claim 2 in which the two thicknesses of material between the corrugations are left unsealed along a notional line running through the edge-nip of the contra-rotating rollers.

4. The invention of claim 3 in which the two thicknesses of material are left unsealed along said line by offsetting the said sealing surface laterally from that line.

5. The invention of claim 4 in which there are two oppositely-offset sealing surfaces each bearing against a corresponding face of a respective one of the contra-rotating rollers.

6. The invention of claim 5 in which the two sealing surfaces lie one on each side of a groove formed in the edge of a roller or slipper.

7. The invention of any of claims 1 to 4 in which the sealing surface is a spherical surface.

8. The invention of any of the preceding claims in which the sealing surface is resiliently biassed into contact with the material to be sealed by it.

9. A machine, or a process, for producing a succession of multi-tube packs, substantially as described herein with reference to and as illustrated in Figures 1 to 5 of the accompanying drawings.

10. The invention of claim 9 when modified substantially as described herein with reference to and as illustrated in Figures 7 and 8 of the accompanying drawings.

1 1.The invention of claim 9 or claim 10 incorporating the further feature of a perforating means substantially as described herein with reference to and as illustrated in Figure 6 of the accompanying drawings.

12. Means, relating to an essential element of the invention, suitable for putting or intended to put into effect the invention defined in any of the preceding claims.