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(11) | EP 1 442 996 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Improved flat pack container |
(57) A flat-pack container comprising:-
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[0001] This invention relates to flat-pack containers of the kind comprising a flat rectangular sheet of e.g. cardboard, plastics, or metal film, which can be rolled or folded into a length of tube and assembled into a container by fitting end caps. Thus, simply by rolling or folding, as appropriate, a container of circular, rectangular, or polygonal cross-section can be formed simply by fitting bottom and top caps to its ends, each cap defining a groove of appropriate shape, into which the adjacent edge of the tube length is located.
[0002] Such containers are normally used as pots for lightweight contents, e.g. for containing pens, pencils etc, and also as wastepaper baskets.
[0003] A particular problem with such containers is that the ends are not fixedly located in the grooves of their respective end caps. An arrangement is known in which protrusions are formed at spaced positions around the groove wall which tends to press against the tube edge when fitted. However, since the fit of the end caps relies on friction, this does not produce positive locking, with the result that the container cannot be used for contents of any significant weight.
[0004] The object of this invention is to provide a flat-pack container of the kind discussed above which provides positive locking for at least the bottom end cap.
[0005] According to the present invention there is provided a flat-pack container as defined in Claim 1.
[0006] According to a further embodiment of this invention a flat-pack container of the kind comprising a sheet of suitable material to be rolled or folded into a tube length of a required cross-section and top and bottom end caps for the ends of the tube, each end cap defining an endless groove corresponding to the cross-section into which an adjacent end edge of the tube is to fit, wherein one of the groove walls of the bottom end cap is provided at spaced locations with a projection which is shaped to provide a lead-in face and a rear retaining face, wherein the other groove wall at least at said spaced locations has an opposed face directed towards said retaining face, and wherein the sheet is provided with appropriately shaped apertures at spaced locations corresponding to the projections adjacent one end edge thereof, the arrangement being such that, in fitting the bottom end cap to its adjacent tube end, the apertures of said tube end are guided by said lead-in and opposed faces of the bottom end cap, to locate over and be positively retained by the retaining faces of their corresponding projections. Preferably at least one of said end caps is provided with a registration mark for aligning the projections on the at least one end cap with the corresponding apertures of the tube.
[0007] In an example, a flat-pack container comprises a sheet of suitable material to be rolled or folded into a tube length of a required cross-section and top and bottom caps for the ends of the tube, each end cap defining an endless groove corresponding to the cross-section into which the adjacent end edge of the tube is to fit, wherein one of the groove walls of the bottom end cap is provided at spaced locations with a projection which is shaped to provide a chamfered lead-in face and a rear retaining face, wherein the other groove wall is angled towards said retaining face, and wherein the sheet is provided with appropriately shaped apertures at spaced locations corresponding to the projections adjacent its bottom end edge, whereby, for fitting, the tube end and bottom end cap are aligned with respective projections and apertures in registration and pushed together, thereby causing portions of the tube edge adjacent the projections to be guided by the lead-in and the angled face of the projections to locate the apertures over their respective projections and be retained by said retaining faces.
[0008] In an example the top end cap is also provided with similar projections and the top edge of the sheet is provided with corresponding apertures.
[0009] In order that this invention may be readily understood, one embodiment will now be described with reference to the accompanying drawings, in which:-
Figures 1-3 and 3A are plan views of a container sheet having different incisions;
Figure 4 is an exploded, fragmenting, half-section of the tube formed from the sheet and bottom end cap;
Figure 4A is an enlarged detail of part of Figure 4;
Figure 5 is a plan view of a bottom end cap;
Figure 6 shows a cross-section through an end cap with internal flanges;
Figures 7 and 8 and 9 show cross sections through a groove in an end cap.
Figures 10, 11 and 12 are cross sections through a groove in an end cap according to other embodiments of the invention;
Figure 13 shows a plan view of a further container sheet having different incisions.
Description of preferred embodiments
[0010] Embodiments of the present invention are described below by way of example only. These examples represent the best ways of putting the invention into practice that are currently known to the Applicant although they are not the only ways in which this could be achieved.
[0011] The tubular body of the container may be formed from a rectangular sheet of suitable material e.g. polypropylene that is rolled into a tube and retained in this form by the end caps. Alternatively, the tubular body may be provided as a tubular unit; this tubular unit may be folded flat for storage or transportation of the container.
[0012] Referring to Figure 1 of the drawings, a container sheet 1, which is preferably of plastics such as polypropylene, is rectangular, with a series of three flaps 2 at one end, and a corresponding series of three shaped tabs 3 at the other end, for retaining the sheet in the form of a tube 4 (see Figure 4) after rolling or folding.
[0013] Referring to Figures 4 and 5, a bottom end cap 6 is circular in this embodiment and has a peripheral wall 7 in which is defined an endless, circular groove 8 corresponding to the circular cross-section of the tube 4.
[0014] The cap in this embodiment is also preferably of plastics, such as PVC, and the end wall 9 thereof is suitably strengthened to resist significant loading, in the embodiment by ribs 10.
[0015] At spaced locations around the groove 8, corresponding to the spacing of the incisions 5, one groove wall 8A (see Figure 4A) is provided with projections each being shaped to provide a chamfered lead-in 12 and a rear retaining face 13, and the other groove wall 8B is angled towards the projection, as shown. Thus, for fitting, the tube 4 is aligned with the bottom end cap 6 with its incisions 5 in registration with the projections, which operation can be facilitated by a registration mark or projection 14 on the wall 7 of the bottom cap 6 (see Figure 5). For assembly, the two components are pushed together, whereby the lead-in chamfers 12 of projections 11 cause adjacent portions of the tube end to be pushed inwardly, and thereafter outwardly by the angle of the groove wall 8B, and hence cause respective incisions 5 to ride over and be positively retained by the retaining faces 13.
[0016] It will be appreciated that the top end cap (not shown), in the form of an annular ring, could be similarly provided with spaced projections for the incisions 5 at the top end of the tube 4.
[0017] It will be appreciated that in this invention engagement means to retain the tubular body of the container within the groove 8 of the end cap are provided by a positive interlocking between the incisions 5 in the container sheet 1 and the projections of the groove of the end cap. In this context, incision means any cut or series of cuts or penetration(s) which serve to provide a seat for projection(s) located on the groove wall, wherein the cut or cuts are shaped, positioned and aligned in any arrangement which creates a surface or surfaces capable of engaging with projection(s) to anchor the tubular container body to the end cap, and wherein the incision does not remove any material from the container sheet.
[0018] The positive interlocking between the incisions and the projections of the end cap may be achieved by using single spaced cuts to maintain the position of the container body within the end cap, as in Figure 2. It will be appreciated that the number of cuts per incision and number of spaced incisions along the longitudinal edge of the container sheet is determined by the arrangement of the projections of the groove.
[0019] The incisions are formed in the manufacturing process as at least one cut in substantially parallel alignment with the longitudinal edge of the container sheet. Figure 1 illustrates a preferred embodiment of the invention in which each incision comprises a rectangular aperture cut out of the sheet. The incisions are at spaced locations along the length of the longitudinal edge of the container sheet, corresponding to the spacing of the projections of the inner groove of the end cap. By using incisions instead of perforations/apertures the container sheet 1 is easier to manufacture as it is not necessary to remove the "cut out" portions.
[0020] Figures 3 and 3A illustrate a further preferred embodiment of the invention, each incision comprising a cut 5 which is substantially parallel to the longitudinal edge of the container sheet wherein a transverse cut of considerably lesser length is positioned at each end, having substantially orthogonal alignment and being continuous with the longitudinally aligned cut, said combination being commonly referred to as a flap. It is preferred that the flap is oriented such that the longitudinal edge of the flap is aligned with the ends of the respective lateral, short cuts having closest proximity to the adjacent edge of the container sheet
[0021] Fitting of the container body into the groove of the end cap causes the flap to deflect. The resistance of the flap to this altered alignment causes it to behave like a spring, attempting to recoil back into alignment with the tubular body of the container, and as a consequence of this action the flap resides at the seat of the projection of the inner groove thereby providing a strong positive lock.
[0022] It will be appreciated that, due to the provision of the positive fixing, the flat-pack container, when assembled, has a far wider range of uses than heretofore. Also, by suitable choices of materials, it can be used to contain significant weights and be weatherproof, e.g. for use as plant pots and shrub containers.
[0023] Figure 6 illustrates flanges 30, 31 located internally within a groove 33 around end cap 32. Two different shapes of flange are shown by way of example. The flanges consist of thin plastic protrusions extending from the inside wall and the base of the tube. They are substantially rigid and their function is to force the tube body against the outer wall of the groove and thus retain the locking projections with their respective apertures when the container is in its assembled state. Thus the gap between the outer edge of the flange and opposing groove wall approximates to the thickness of sheet material from which the body is formed. Naturally there is allowance for a clearance fit.
[0024] The top edge of flange 30 is angled down, directing the tube body into the groove 33 during assembly.
[0025] It will be appreciated that in this embodiment the locking projections 38 are positioned between adjacent flanges such that they do not interfere, one with another. There are flanges spaced all around the circumference of the groove by generally only four locking projections.
[0026] Figures 7 and 8 show cross sections though part of an improved end cap according to a further embodiment of the present invention. The end cap 100 contains a groove 102 that has an outer wall 103 and an inner wall 104. The tube end 105 is positioned inside the groove as shown. A retaining surface 106, 107 is provided on one of the groove walls, in this example, on the outer wall 103 and the retaining surface comprises two protrusions 106 and 107. The protrusions 106 and 107 are spaced apart such that one is substantially vertically above the other as shown in Figure 12. The other groove wall, in this example, the inner wall 104 is provided with a lug 108. The lug 108 is provided by a protrusion in the inner wall as shown and is directed towards the retaining surface 106,107. Preferably the lug 108 is directed towards the space between the two protrusions 106 and 107 as shown in Figure 7.
[0027] In a preferred embodiment the lug 108 is provided by a protrusion that forms a ring around the groove wall in the end cap. Alternatively, lugs 108 can be provided as protrusions spaced at intervals around the groove wall.
[0028] When the tube end 105 is placed into the groove 102 it is flexed about the lug 108 which tends to force the tube end towards the outer groove wall 103. At the same time the protrusions 106 and 107 tend to force the tube end towards the inner groove wall 104. As a result of these forces the tube end flexes as shown in Figure 7 and tends to be retained within the groove. If the tube end is pulled up vertically out of the groove the lug 108 and the protrusions 106 and 107 act to prevent the tube end from being withdrawn from the groove.
[0029] Once the tube end wall is flexed in this way indentations 113, 114 and 115 form as shown in Figure 7. The protrusions 106, 107 and the lug 108 fit into these indentations in the tube wall so that the tube is held firmly in the end cap. The indentations can also be pre-formed in the tube. For example, if the tube is made from plastics material then the indentations can be formed by heat-treating the end of the tube.
[0030] The indentations or dimples, 113, 114 and 115 can be formed simply as a consequence of the flexing or bending of the tube end wall as it is pushed into the end cap. Alternatively, the dimples or indentations may be pre-formed in the tube end wall. This can be done during the manufacturing process, for example by moulding, or heat-treating the tube end wall.
[0031] This method of using indentations or dimples in the tube end wall to hold the tube in place around protrusions or lugs in the end cap can be used with many types of flat-pack container. For example, it can be used with flat-pack containers that have two nested tubes.
[0032] As shown in Figure 7 the lug 108 and the protrusions 106 and 107 do not need to extend more than half way across the groove and they may be rectangular. Also the lug 108 and the protrusions 106 and 107 are not necessarily wedge shaped. This means that during the manufacturing process it is possible to use a conventional moulding tool to form the groove profile without deforming or knocking off the protrusions 106, 107 or 108 from the groove walls when the moulding tool is withdrawn.
[0033] It is also possible for the protrusions and the lug to be tapered or wedged for example as shown in Figure 9. The lower face of the protrusions and lugs have sloping edges 120 as shown. The gradient of these sloping edges may be adjusted to suit the particular moulding tool and design requirements. Once the edges are sloping then this helps the moulding tool used to form the groove profile to be withdrawn without damaging the protrusions 106, 107 or 108.
[0034] Figure 8 shows another embodiment of the invention where the tube end contains a perforation 109 as described above. Protrusion 108 fits at least partially into the perforation 109 to enable the tube end to engage positively with the end cap. The protrusions 106 and 107 act to push the tube end towards the lug 108 so that the perforation 109 engages with it. The combined effect of this engaging mechanism and the flexing of the tube end around the lug 108 and protrusions 106 and 107 ensure that the tube end is held within the groove.
[0035] It is also possible to use a protrusion on only one groove wall together with an indentation in the tube to engage with the protrusion. For example consider the situation in Figure 7. If protrusions 106 and 107 are not provided the outer groove wall 103 can itself act to retain the tube end wall against the lug 108. The tube is then held in the end cap 101.
[0036] Figures 10 and 11 show a further embodiment of this aspect of the present invention. In this example the end cap 130 contains a groove 132 comprising an inner wall 134 and an outer wall 133. The tube end is positioned within the groove as shown. The retaining surface in this example comprises a protrusion or nib 137 which projects into the groove. The nib 137 is positioned some distance up from the bottom of the groove to allow room for an outwardly extending dimple 136 to nest below it in a co-operatively engaging fit. The dimple 136 may be formed by deforming the end of the tube in the required region. Methods and equipment for forming such distending dimples are known per se to the person skilled in the art. They usually involve the application of pressure or heat or both whilst forcing the tube material into an appropriately shaped die.
[0037] Accordingly, there is often a corresponding indentation (as shown in Figure 10) in the side of the tube wall opposite the side containing the dimple. This can co-operatively engage with a further protrusion 138 (not shown) on the inner groove wall 134. This may act to form a more secure fit of the tube wall within the groove but requires rather more careful engineering.
[0038] Figure 12 shows a further embodiment of the present invention. In this example, the end cap 140 contains a groove 142 comprising an inner wall 144 and an outer wall 143. The tube end is positioned within the groove as shown.
[0039] The retaining surface in this example comprises a channel 147 which extends for substantially the whole circumference of the groove. The channel 147 is positioned some distance up from the bottom of the groove such that when the tube end is engaged in the groove an outwardly extending dimple 136 nests within it in a co-operatively engaging fit.
[0040] An indentation, positioned in the side of the tube wall opposite the side containing the dimple co-operatively engages with a further protrusion or lug 148 on the inner groove wall 144. In an alternative embodiment, the corresponding indentation may be absent and the wall of the tube may then be flexed about the protrusion of lug 148 such that the tube end is urged towards the outer groove wall 143. This has the effect of ensuring a more secure fit of the tube wall within the groove.
[0041] In principle, the protrusion or nib can take a wide variety of forms. Any extension or projection from one of the groove walls into the groove which can co-operatively engage with a pre-formed shape on the tube wall such that there is a snug, engaging fit will suffice.
[0042] With regards to the shape of nib 137, this is illustrated in Figure 10 as a ridge with generally rounded edges. Unlike the previous examples, where a wedge-shaped protrusion is essential to engage firmly with an aperture in the tube wall, this is no longer necessary. Any shape with an engaging surface 139 directed substantially towards the bottom of the groove will suffice.
[0043] In fact, the chamfered rounded edges on the nib 137 offer definite advantages. They simplify manufacture considerably and ease the passage of the tube end as it is forced into the bottom of the groove.
[0044] In a preferred version the nib 137 runs substantially the whole circumference of the groove. Once again, this arrangement is simple to manufacture. The dimples may be spaced periodically around the tube wall end. Their spacing is not critical, providing they are distanced from the edge of the tube wall end to form a tight engaging fit with the nibs/ridge 137 once inserted.
[0045] It is also possible for the dimple 136 to extend for substantially the whole length of the tube end. Once again this may simplify manufacture because the tube ends can simply pass through a heated roller/die during the production process.
[0046] The ribs 10 shown in Figure 5 can also serve another purpose as well as acting as strengtheners. They can be arranged to urge the tube body against the outer groove wall. That is to say, the ribs 10 may extend almost to the outer groove wall, leaving a gap substantially equivalent to the thickness of the tube material. This arrangement provides a particularly solid feel to the assembled product.
[0047] This arrangement also creates discreet cavities or sectioned off areas 151 within the perimeter of the end cap. It has unexpectedly been discovered that, by forming foldable tabs 150 in the edges of the tube body, these engage in these cavities to prevent rotation of the tube with respect to the end cap. This prevents inadvertent dis-assembly of the container.
[0048] In practice the tabs 150 are formed by making two small cuts in the edge of the sheet and at right angles to the edge. Perforations are formed parallel to the edge of the sheet and in a line between the two cuts and displaced from the edge of the sheet by a dimension substantially the same as the depth of each cut.
[0049] During assembly these tabs 150 are bent inwards towards the centre of the container. They then automatically engage with one of the cavities 151.
Whilst one tab is sufficient to add rotational stability, it is preferable to include a plurality of tabs at each end of the tube.
1. A flat-pack container comprising:-
(i) a sheet of material adapted to be rolled into a tube length to form the body of the container; and
(ii) top and/or bottom end caps, each end cap defining a groove corresponding to the cross-section of the tube length, wherein a wall of the groove is provided at special locations with projections extending into the groove;
wherein the sheet is provided with appropriately shaped incisions at spaced locations corresponding to the projections.2. A container as claimed in claim 1 wherein the incisions comprise at least one cut
of discrete length wherein the cut is formed so as to fully pierce the container sheet
and is aligned parallel with the adjacent edge of the container sheet and positioned
so as to correspond to the projection of the end cap.
3. A container as claimed in claim 1 or claim 2 wherein the projections of the inner
groove wall are shaped to provide a chamfered lead-in face and a rear retaining face,
whereby, for fitting, the tube end and end cap are aligned with respective projections
and incisions in registration and pushed together, thereby causing portions of the
tube edge adjacent the projections to be guided by the lead-in and the angled face
of the projections to locate the incisions over their respective projections and to
be retained by said retaining faces.
4. A container as claimed in any of claims 1 to 3 wherein the incision comprises a cut
which is substantially parallel to the longitudinal edge of the container sheet wherein
a transverse cut of considerably lesser length is positioned at each end, having substantially
orthogonal alignment and being continuous with the longitudinally aligned cut, said
combination being commonly referred to as a flap.
5. A container as claimed in claim 4 wherein the flap is oriented such that the longitudinal
edge of the flap is aligned with the ends of the respective lateral, short cuts having
closest proximity to the adjacent edge of the container sheet.
6. A container as claimed in any preceding claim wherein the groove of at least the bottom
end cap incorporates a plurality of flanges, said flanges extending radially into
the groove and being adapted to urge the body of the container against the projections
in the groove.
7. A container as claimed in Claim 6 wherein the top edges of said flanges are angled
to direct the container body into said groove during assembly.
8. A flat-pack container comprising:-
(i) a tube length adapted to form the body of the container;
(ii) top and bottom end caps, each cap defining a groove corresponding to the cross-section of the tube length;
(iii) engagement means adapted to retain, in use, each end of the tube in a respective end cap;
wherein the engagement means comprises a retaining surface on one of the groove walls and one or more pre-formed indentation(s) or dimple(s) in the tube end wall.9. A container as claimed in claim 8 wherein the retaining surface is a protrusion or
lug.
10. A container as claimed in claim 8 wherein the retaining surface comprises an indentation.
11. A container as claimed in claim 10 wherein the one or more pre-formed indentation(s)
or dimple(s) extend outwardly from the tube wall and are adapted to co-operatively
engage with the retaining surface.
12. A container as claimed in any of claims 8 to 11 wherein the retaining surface extends
substantially continuously around one of the groove walls.
13. A container as claimed in any of claims 8 to 12 wherein the retaining surface is on
the outer groove wall.