PACKAGING TUBE MADE OF CORRUGATED BOARD, METHOD AND APPARATUS FOR ITS MANUFACTURE

Abstract: A tube (1) for use primarily as the body of a tubular packaging container is made of packaging sheet material comprising a facing sheet and a spacer sheet, for example single faced corrugated board, and is formed with an integral inturned flange (2) to maintain its tubular shape. Apparatus for forming such a tube is also disclosed.

Description: PACKAGING TUBE MADE OF CORRUGATED BOARD, METHOD AND APPARATUS FOR ITS MANUFACTURE This invention relates to containers made of 5 packaging sheet material comprising a backing sheet and a spacer sheet, for example single faced corrugated board. The invention is particularly but not exclusively concerned with comparatively large containers for bulk products such as powdery or granular 0 materials. Containers made of single or double faced corrugated board are already made in many shapes and sizes, mainly substantially rectangular or in any event with sharply defined corners between adjoining side 5 walls . Circular cylindrical containers have certain notable advantages, for example in economy of use of board and in resistance to axial loading and internal radial loads. However their use has been limited for a number of reasons . One problem is that they have to be 0 formed up manually on a cylindrical mandrel of the same length as the container, and furthermore a different diameter mandrel is needed for each diameter of container, which is expensive in terms of both the forming equipment itself and space for storing it, and 5 in particular makes it impracticable for end users to make up their own containers on site . Viewed from one aspect the present invention provides a tube made of packaging sheet material comprising a backing sheet and a spacer sheet, such tube 0 comprising at least two layers of said sheet material bonded together face to face . A tube according to the invention may be of any rounded shape in transverse cross-section, without sharp corners, which may in practice be used to make a 5 container body, including elliptical, oval and the like in addition to circular, and it need not be of constant cross-section, e.g. it could be circular for part of its length and non-circular elsewhere. Alternatively it could have straight or curved sides with rounded corners, or it could comprise a combination of curved sides and straight sides. The tube is preferably formed of two layers of sheet material all around its circumference, but the scope of the invention also extends to a tube which is only partly formed of two layers, for example only in a region where the ends of a single layer overlap each other. In one form of the invention the tube is of such a length as to be suitable for forming a tubular body of a packaging container, for example of a length at least as great as its width. However the tube can alternatively be of substantially ring-like configuration, for use in forming an end closure of a tubular packaging container. Conceivably the said layers of sheet material making up the tube could be individual layers bonded together one on another. Preferably however the sheet material is a continuous length wound spirally on itself to form the said layers . Preferably the sheet material is applied as a laminate of the said backing sheet and spacer sheet already bonded to each other, but it would be possible to apply the two said sheets separately and only bond them together as the tube is being formed. The backing sheet and spacer sheet making up the said sheet material may be of any suitable form. The backing sheet will usually be of paper. The spacer sheet could be a low density material such as foam, for example of polyethylene or polystyrene, or a biodegradable foam, in which case it may be necessary to include a second backing sheet to protect the foam. Preferably however the spacer sheet is corrugated paper board, with the corrugations running lengthwise of the tube. Thus the said sheet material preferably comprises single faced corrugated board, although double faced board or other sheet material having two backing sheets and a spacer sheet may also be used. Another problem with circular cylindrical and the like containers is that they have little resistance to transverse loading, particularly in the region of an open end, which makes it necessary to provide the container with additional structural features to stiffen it, which is much less necessary with rectangular containers . The layers of the tube may be bonded together by a suitable means, for example glue, or by a hot melt adhesive, or by a thermosetting resin. Any necessary heating is preferably effected by means of hot air. According to a preferred feature of the present invention the tube is formed with an integral, contiguous, turned in or turned out flange extending around at least one end thereof. Such a flange holds the tube in its desired cross-sectional shape so that full advantage may be taken of the resistance to axial loading provided by a rounded tubular configuration. No further structure is needed to resist transverse loading, and furthermore formulation of the tube without using an elongate mandrel is facilitated. All that is needed is a mechanism for forming the flange and guiding the same into a circular or other rounded configuration, which mechanism may be much smaller than a mandrel and furthermore may be made adjustable to form tubes of different diameters. Such a flange is preferably continuous all around the tube, but it could be discontinuous or of varying radial dimensions. Means must of course be provided for holding the said flange in its turned in or turned out position. Conceivably this could be achieved by stapling or stitching. Very preferably however the flange is held in position by the same bonding means, e.g. a suitable glue, as is used to bond together the layers of sheet material forming the tube, which may be applied to the flange before and/or during the operation of turning it in or out and which upon hardening causes the flange to substantially solidify in its turned in or turned out condition. If the flange is turned in, the solidifying effect is assisted and enhanced by the deformation, i.e. compacting, of the flange material which necessarily occurs as it is turned in and its radius is thereby reduced. Preferably the flange is compressed, i.e. squeezed, in the direction of its thickness, i.e. in the direction of the length of the tube, during or after the turning in or out and bonding operation, to assist and enhance its substantial solidification, and to reduce its circumference if the flange is turned in. If the flange is turned out, and the tube is made of corrugated board, the corrugations will have to be flattened at least to some extent to provide the increased area of board material needed to form a flange of larger radius than the body of the tube, and such flattening may for example be permitted by forming a series of short cuts in the facing sheet of the board in the area of the flange, parallel to the corrugations. Conceivably the said flange could be formed, i.e. turned in or out, either before or after the tube has been formed, that is the flange could be turned in or out either while the packaging sheet material is still flat or after it has been formed into a tube. Preferably however the flange is formed during the process of forming the tube. It can then be turned in or out by any suitable mechanical means, for example an elongate curved forming plate or a series of rollers set at successively greater angles to the tube axis, both in conjunction with means for feeding the sheet material therethrough. The use of single faced corrugated board to form a tube according to the invention is particularly convenient in that it lends itself to the use of an elongate knurled or ribbed feed roller, or one or more ribbed belts, whose teeth fit the corrugations of the board, to feed the board through an apparatus for forming the tube. However, if the spacer sheet is of some other, non-corrugated, material such as a suitable foam, a roller or belt with a high friction, e.g. roughened, surface may be used. A knurled or ribbed feed roller when used to feed single faced corrugated board as just mentioned lends itself particularly to the operation of bonding together the layers of board to form the tube in that the leading end of a strip of board, having been led around into a tubular configuration after first passing the feed roller, may then be fed back into the nip between the feed roller and the back-up roller so as to be reengaged with the teeth of the feed roller and pressed between the rollers to bind the two layers of board together, e.g. by glue, as they continue to be fed. Clearly such a process may be applied to the formation of a tube with three or more layers of board if desired. This process of forming a tube made of two or more layers of single faced corrugated board may furthermore be applied to the formation of such tubes without a flange. As mentioned above, the said flange is preferably formed at the same time as the tube is formed. The tube may be formed in any convenient manner, for example by guiding the partially turned in flange around the edge of a former comprising a suitably shaped, e.g. circular, member of preferably minimal axial dimension, such as a circular disk, while the flange is hardening, i.e. solidifying. The -flange, if turned in, could lie on top of such a disk while being held down by a pressure roller, or it could be received in an outwardly facing annular slot in the edge of such a disk, or in a gap between the edge regions of two parallel disks slightly spaced from each other axially. A gap may be provided in the top wall of such a slot, or in the upper one of such two disks, for a pressure roller to press down on the flange to compress, i.e. squeeze it as it is being formed, as previously mentioned. Such a pressure roller will preferably be spring loaded, to accommodate the increase in thickness of the flange as more than one layer of board is rolled into it. Either of the above ways of forming the tube would need a separate former for each different diameter of tube that might be required. As an alternative, a former adjustable to make tubes of different diameters could comprise a series of pairs of guide rollers depending vertically from respective horizontal arms radiating from a central support and adjustable radially along such arms so that the series of pairs of rollers constitute a guide track of adjustable diameter. Alternatively the pairs of rollers could be fixed on the arms and the arms themselves adjustable radially. When a tube according to the invention is formed with a flange at one end, a panel of packaging sheet material such as double faced corrugated board for example, may be used to close the flanged end of the tube, the panel preferably being glued to the flanged end using a hot melt adhesive which will fill the slightly uneven surface of the flange, brought about by the deformation of its material during formation. A suitable closure for the other end of the tube, which will usually be plain, i.e. unflanged, may take the form of a flanged collar formed by a short flanged tube made in accordance with the present invention and dimensioned to fit in or over the plain tube end. A closure panel may be secured to the flange of such a collar in the same way as mentioned above. It may be necessary to trim around the unflanged end of the tube to provide a flat end, particularly if it is multi-layered. Any other suitable end closure may be used, for example a plastics cap. Alternatively the tube could be secured upright on a pallet which would then close the bottom end of the tube . Viewed from another aspect the present invention provides a method of making a spirally wound tube as set forth above, including the step of winding the said sheet material on itself in spiral fashion to form the layers of the tube. When the said tube is flanged as described above, the said method may include the step of forming the said f-lange by a continuous process at substantially the same time as the packaging sheet material is formed into a tube. Preferably the layers of sheet material are glued together in both the flange and the tube body, the glue preferably being applied before the winding into tubular form has begun. The edge region of the sheet material where the flange is to be formed may be wetted (as well as glued) prior to formation of the flange, to make it more amenable to forming. Wetting may be effected by the application of water or steam. Tubes made in accordance with the invention may incorporate one or more layers of material other than corrugated board, for example a waterproof layer or a hermetic sealing layer made of coated board and/or metal foil. Viewed from a further aspect the present invention provides apparatus for forming a spirally wound tube as set forth above, such apparatus comprising a bonding means applying station, a tube forming station, and means for feeding the said sheet material through the said stations in the direction of its length. In a preferred form the apparatus also includes a flange forming station as the most upstream station, followed by the said bonding means applying station, followed by the said tube forming station. The mechanism at the said flange forming station may comprise a series of pairs of guide rollers for receiving the edge region of the sheet material along which the flange is to be formed, and a series of forming rollers associated with the said guide rollers, arranged to fold over the edge region of the sheet material to form the flange. Alternatively such mechanism may comprise a stationary forming plate for engaging the edge region of the sheet material and folding it over, to form the flange. The said feeding means for the sheet material may comprise a feeding member having a knurled or ribbed continuous surface, for example a longitudinally knurled or ribbed roller with an associated back-up roller, or one or more ribbed belts, as previously mentioned. The use of a ribbed belt is advantageous if relatively complex shapes of tube are to be formed. The mechanism at the said tube forming station may include a freely rotatable former having a continuous forming edge of the same shape as the desired cross- sectional shape of the tube, arranged to have the sheet material extend around it as the material is fed. Such mechanism may further include means for releasably attaching the leading end of the sheet material to the said former, and a pressure roller arranged to press the said flange against the edge region of the said former. Some embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: FIGURE 1 is a perspective view of a flanged tube according to the invention, partly broken away; FIGURE 2 is a perspective view of an apparatus according to the invention, for making a tube as shown in Figure 1; FIGURE 3 is a plan view of the apparatus of Figure 2; FIGURES 4 to 6 are plan views of the apparatus, illustrating successive stages in the formation of the tube of Figure 1; FIGURE 7 is a perspective view of the tube forming station, to a larger scale; and FIGURES 8 and 9 are plan views of formers for use in the apparatus to make tubes of other shapes . Referring first to Figure 1, a tube 1 according to the invention is made of single faced corrugated board and is intended to form the tubular body of a comparatively large packaging container, e.g. for powdery or granular material. The tube 1 comprises two layers of board, wound spirally on each other, with the corrugated ply on the inside. At one end the tube is formed with an integral inturned flange 2, contiguous with the body of the tube, which .holds it in its tubular configuration and also provides an annular receiving surface for an end closure (not shown) in the form of a disk, e.g. of corrugated board, which will in due course be glued to the flanged end of the tube. Referring now to Figures 2 and 3 , an apparatus for forming the tube 1 comprises three stations, namely a flange forming station 3, a gluing station 4, and a tube forming station 5. A strip of single faced corrugated board, with the flutes of the corrugated ply running transversely, will pass through the apparatus from left to right as seen in the Figure, to be formed up into the tube 1. The mechanism at the flange forming station 3 comprises a series of pairs of vertical rollers 6 arranged to receive the top edge . (i.e. one of the side edges) of the strip of board between them, and a further series of inclined rollers 7 mounted above the rollers 6 to form the flange as the board is fed through this station. The flange region of the board may be passed through the nip of a meshing pair of fluted rollers (not shown) prior to formation of the flange, to induce a pattern of crimps in the flange region, thereby reducing the rigidity of the board to make it easier to distort it. The mechanism at the gluing station 4 comprises a glue applicator roller 8 which is supplied with glue from a reservoir 9 by way of a tube 10 with its outlet above the top end ' of the roller. A scraper blade 11 engages the cylindrical surface of the roller 8, and another scraper blade 12 engages its top surface, from which glue is applied to the underside of the flange 2. The gluing mechanism is pivotally mounted by way of a bracket 13 and is spring biassed towards a position engaging the board in operation. An arm 14 on a separate, fixed, pillar 15 engages on top of the flange 2 in operation. The mechanism at the tube forming station 5 comprises a driven, ribbed feed roller 16 for feeding the board through the apparatus, with an associated spring based back-up roller 17, a circular forming disk 18 around which the board is guided to form it into a tube, and a pressure roller 19 for pressing down on the tube flange 2 during such operation. The forming disc 18 is mounted by way of two pivoted arms 20 and 21 from a main support pillar 22 and is biassed into its operative position by a tension spring 23. The pressure roller 19 is also biassed, downwardly, into its operative position by a tension spring 24 acting on an arm 25 which mounts the roller. The roller is movable about a vertical axis between an out of the way position shown in Figures 2 to 5 and an operative position shown in Figure 6. Referring now to Figure 4, single faced corrugated board from a supply roll 26 has its leading end 27 fed manually between the rollers 6 at the flange forming station 3, to form the flange 2. The board is then passed through the gluing station 4 (which is not yet operative) and engaged with the feed roller 16 at the tube forming station 5. At this point the leading end of the flange 2 is engaged under a clip 28 mounted on the top of the forming disk 18. The feed roller 16 is now activated. The forming disk 18, being biased towards the board by spring 23, has its forming edge 29 urged into contact with the inside (corrugated) face of the board, immediately below the flange 2, as the board is fed by the feed roller 16. As a result the board continues to engage with the forming edge of the disk as it is fed by the feed roller, so that the board is drawn into a circular configuration, wrapped around the disk 18, as shown in Figure 5. When the leading edge of the board reaches the position shown in Figure 5, the glue roller 8 is engaged with the board, as shown, so that the corrugated side of the board is continuously glued from this point onwards. Then, when the leading edge 27 of the board again approaches the feed roller, as seen in Figure 6, it is released from the clip 28, enters the nip between the feed roller and its back-up roller 17, and is pressed face to face against the board which is just now entering the tube forming station. At this point, the pressure roller 19 is brought into its operative position as shown in Figure 6, and presses down on the top of the flange 2 under the influence of its spring 24. The operation then continues until a desired number of layers have been built up and the tube is fully formed. Further details of the tube forming station will be clear from the enlarged view shown in Figure 7. Figures 8 and 9 show alternative shapes of forming disk for forming respectively a square section tube with rounded corners, and a triangular section tube again with rounded corners . These forming disks have to be driven in rotation in operation, to keep them in contact with the board, and the arm 21 also has to be spring biassed in the upstream direction. It should be understood that the apparatus particularly described above may readily be modified to form a flanged tube with its axis horizontal rather than vertical. Indeed, such a modification is likely to be more suitable for large scale production, particularly from the point of view of glue application. The method and apparatus of the present invention lend themselves particularly to the forming of tubular containers by an end user, on site, and, if required, to a relatively small scale of output, in that an elongate mandrel is not required, which leads to a large saving in both storage and operating space, and in that the forming apparatus may be of a simple, reliable and inexpensive nature .

Claims: Claims : 1. A tube made of packaging sheet material comprising a backing sheet and a spacer sheet, such tube comprising at least two layers of said sheet material bonded together face to face. 2. A tube as claimed in claim 1, which is of such a length as to be suitable for forming a tubular body of a packaging container. 3. A tube as claimed in claim 2, whose length is at least as great as 'its width. 4. A tube as claimed in claim 1, which is of substantially ring-like configuration, for use in forming an end closure of a tubular packaging container. 5. A tube as claimed in any preceding claim, wherein said sheet material is wound spirally on itself to form said layers . 6. A tube as claimed in any preceding claim, which is formed with an integral, contiguous, turned in or turned out flange extending around at least one end thereof. 7. A tube as claimed in claim 6 , wherein the said flange is held in position by the same bonding means as bonds together the layers of sheet material forming the tube . 8. A tube as claimed in claim 6 or 7, having a panel of packaging sheet material secured across the flanged end of the tube, as an end closure. 9. A tube as claimed in any preceding claim, wherein said sheet material comprises paper as said backing sheet and corrugated paperboard as said spacer sheet, the corrugations running lengthwise of the tube. 10. A tube as claimed in claim 9, wherein said sheet material comprises single faced corrugated board. 11. A tube as claimed in any preceding claim, which is circular in transverse cross-section. 12. A tube as claimed in any of claims 1 to 10, which is substantially oval or elliptical in transverse cross- section. 13. A tube as claimed in any of claims 1 to 10, which has at least three straight or curved sides in transverse cross-section, with rounded corners between the sides. 14. A packaging container including at least one tube as claimed in any of claims 1 to 13. 15. A packaging container as claimed in claim 14 when dependent directly or indirectly on claim 2, wherein the said tube forms at least part of a tubular body of the container. 16. A packaging container as claimed in claim 15, wherein the container body is formed by two or more of said tubes partly telescoped together. 17. A packaging container as claimed in claim 15 or 16, wherein the said tubular body is secured upright on a pallet which forms the base of the container. 18. A packaging container as claimed in claim 14 when dependent directly or indirectly on claim 4, wherein the said tube forms part of an end closure of the container. 19. A method of making a tube as claimed in claim 5, or any of claims 6 to 13 when directly or indirectly dependent on claim 5, including the step of winding the said sheet material on itself in spiral fashion to form the layers of the tube . 20. A method as claimed in claim 19, wherein the said backing sheet and the said spacer sheet are supplied separately to a tube forming station. 21. A method as claimed in claim 19, wherein the said backing sheet and the said spacer sheet are supplied in the form of a composite sheet to a tube forming station. 22. A method as claimed in claim 21, wherein the said composite sheet comprises single faced corrugated board. 23. A method as claimed in any of claims 19 to 22, when dependent directly or indirectly on claim 6, including the step of forming the said flange by a continuous process at substantially the same time as the packaging sheet material is formed into a tube. 24. A method as claimed in any of claims 19 to 23, including the steps of feeding the said packaging sheet material by means of a member having a knurled or ribbed continuously moving surface. 25. A method as claimed in claim 24, wherein the said feeding member is a longitudinally knurled or ribbed roller. 26. A method as claimed in claim 24, wherein the said feeding member is a ribbed belt . 27. A method as claimed in any of claims 24 to 26, wherein the said packaging sheet material is single faced corrugated board and the said knurls or ribs fit with the corrugations of the board. 28. Apparatus for forming a tube as claimed in claim 5, or any of claims 6 to 13 when directly or indirectly dependent on claim 5, such apparatus comprising a bonding means applying station, a tube forming station, and means for feeding the said sheet material through the said stations in the direction of its length. 29. Apparatus as claimed in claim 28, when dependent directly or indirectly on claim 6, further including a flange forming station. 30. Apparatus as claimed in claim 29, wherein the said flange forming station is the most upstream station, followed by the said bonding means applying station, followed by the said tube forming station. 31. Apparatus as claimed in claim 29 or 30, wherein the mechanism at the said flange forming station comprises a series of pairs of guide rollers for receiving the edge region of the sheet material along which the flange is to be formed, and a series of forming rollers associated with the said guide rollers, arranged to fold over the edge region of the sheet material to form the flange. 32. Apparatus as claimed in claim 29 or 30, wherein the mechanism at the said flange forming station comprises a stationary forming plate for engaging the edge region of the sheet material and folding it over to form the flange . 33. Apparatus as claimed in any of claims 28 to 32, wherein the said feeding means for the sheet material comprises a feeding member having a knurled or ribbed continuous surface. 34. Apparatus as claimed in claim 33, wherein the said feeding member is a longitudinally knurled or ribbed roller, with an associated back-up roller. 35. Apparatus as claimed in claim 33, wherein the said feeding member is a ribbed belt. 36. Apparatus as claimed in any of claims 33 to 35, for forming a tube from single faced corrugated board with its flutes extending transversely, wherein the said knurls or ribs are arranged to fit with the corrugations of the board. 37. Apparatus as claimed in any of claims 28 to 36, wherein the said feeding means for the sheet material is at the said tube forming station. 38. Apparatus as claimed in any of claims 28 to 37, wherein the mechanism at the said tube forming station includes a rotatable former having a continuous forming edge of the same shape as the desired cross-sectional shape of the tube, arranged to have the sheet material extend around it as the material is fed. 39. Apparatus as claimed in claim 38, including means for driving the said former in rotation. 40. Apparatus as claimed in claim 38 or 39, including means for releasably attaching the leading end of the sheet material to the said former. 41. Apparatus as claimed in any of claims 38 to 40, wherein the mechanism at the said tube forming station further includes a pressure roller arranged to press the said flange against the edge region of the said former.

Inventors: IZZARD PAUL, KYNASTON-PEARSON ANTHONY WILLI, IZZARD, PAUL, KYNASTON-PEARSON, ANTHONY, WILLIAM, NIGEL
Applicants: IZZARD PAUL, KYNASTON PEARSON ANTHONY WILLI, SCA PACKAGING LTD, IZZARD, PAUL, KYNASTON-PEARSON, ANTHONY, WILLIAM, NIGEL, SCA PACKAGING LIMITED
Application year: 1998
Main classification: B65D3
IPC codes: B31C1, B31F1, B65D3