GB2485077A - Accurate, Close Fitting, Fluted Polypropylene Box - Google Patents

Abstract

A box blank has a base, sides shorter than the length L of the base and end walls having tabs wrapping around the corners and engaging, by means of wedge- or dovetail-shaped projections, corresponding recesses in the side walls (Figure 4). PVC reinforcements may be provided at the joins between the tabs and side walls. The box can be formed from fluted polypropylene extruded board by scoring without cutting fold lines using a v-shaped wheel, greater pressure being applied across the grain, the board being overfolded e.g. by 120 degrees (Figure 7) and heat applied along the external edges to reduce stress and resistance to folding, allowing the sides to naturally stand at 90 degrees to the base. The blank is dimensioned to allow for compression and reduction of the material during the heat folding process and the edges of the base not bordering a side wall (8, Figure 3) are extended and have a chamfered corner for flush finish after folding. A lid for the box extends 75% of the depth of the box for easy removal. The sides of the box do not bow outwards and the material can be digitally printed.

Description

Page 1 Description Title: Point-of-Sale and Re-usable Box Packqging

Introduction & Background:

A customer needing a tow-cost Point-of-Sale packaging solution is typically constrained by either: -the min-imum order quantities for Lithographically printed boxes to achieve the lowest price/box which means high up-front charges (eg: Lithographic printed box/cutting run can be »=1000 off); or a sliding scale of box prices versus order quantity for digitally printed tailored' cardboard box designs (eg: «=100 off for digitally printed boxes).

This sliding-scale of box prices can still mean the customer has to pay sizeable up-front charges (to reach an acceptable unit price/box) even for generic box designs (eg: folding Pizza box) that are tailored to the customer's specified dimensions, digitally printed and then cut-out ready for folding.

To avoid these high up-front charges (and large' minimum quantity print runs for cardboard box designs) an alternative box design has been conceived typically, suitable for low-medium production runs (using light-weight cellular-plastic extruded board) that can be digitally printed, digitally cut-out (in-the-flat) and then folded/formed into a precise 2-part box (suitable for Point-of-Sale packaging or as storage box packag-ing).

Summary/Statement of Invention:

A 2-part box design has been created using a light-weight, stiff plastic typically, polypropylene extruded board material, featuring a developed shape with interlocking tabs, wrap-round radiused corners and using a heat-forming technique that overcomes the material's natural reluctance to remain in a folded/bent posi-tion. The Top lid fits over the Base and the Top lid extends to substantially 75% of the assembled box's depth, so that extra protection is afforded by the double wall thickness and this ratio provides easy ergo-nom ic removal/replacement of the close-fitting lid.

It is understood that this anisotropic plastic material is not used for accurate box/packaging applications due to its natural reluctance (and direction dependency) to remain at substantially 90° (without bowing) when bent/folded into a 3-dimensional box shape.

This in-the-flat' design allows the box to be digitally printed, digitally cut-out and subsequently formed into an accurate 3-dimensional 2-part box, overcoming the need for significant up-front costs and high' mini-mum batch sizes (associated with conventional lithographic and digital printing of standard cardboard box designs).

This design solution offers a lower cost alternative to firms/entrepreneurs that need a high-quality presen-tation box (e.g. 1400-2200 dpi resolution on large X-Y format digital printing machines as now achievable), for low-medium volume product launch/market test applications, whilst also needing to limit costs and business risks.

The robustness, durability, stiffness of the plastic cellular material combined with the close-fitting inte- grated box design, makes this design solution attractive for applications requiring long-life and for protect-ing high-value contents.

The high-accuracy/repeatability in manufacture of the digitally-cut out in-the-flat developed shape means that this design solution is also suitable for automated manufacture and assembly for applications that re-quire high-volume typically, >1000 off batch sizes and optimum unit cost versus volume.

Page 2

Introduction to the Detailed Description

The invention will now be described by way of an example of an embodiment of this design solution and with reference to the following accompanying drawings:-List of Figures: Fig 1: A pictorial view showing the cross-section of the plastic typically, polypropylene square fluted-board extruded material.

Fig 2: A plan view showing the in-the-flat developed shape of the design and the key dimensions that are proportionately increased.

Fig 3: Partial view showing the geometry of the side and end wall and one of the Extended twin-angled tabs'.

Fig 4: Isometric view (looking down inside the box bottom) showing one of the wrap-round corner radiuses and the extended twin-angled tabs engaged with the side wall.

Fig 5: Partial Isometric view showing the Box lid (or upturned bottom) with the locally projected closure to the extended-tab (when the box is formed into its 3-dimensional box shape) Fig 6: Isometric View showing the developed shape in-the-flat with the V-shaped Crease lines formed into the surface.

Fig 7: Isometric View of the Side-walls showing the over-bend through an angle of substantially 12O014O0 with heat uniformly applied to the external edge.

Fig 8: Isometric View of the End-wall showing the over-bend through an angle of substantially 120°-140° with heat uniformly applied to the external edge.

Fig 9: Isometric View showing the heat-formed side/end walls when at their neutral un-stressed state and at substantially 9O°to the box's top/bottom surface.

Fig 10: Isometric View showing the engaged interlocking tabs and internal thin self-adhesive plastic typical-ly, rigid PVC reinforcement pieces in place.

Fig 11: Isometric View showing the locally applied PVC tape right-angled shapes over the twin-angled inter-locking extended tabs and along the top of the extended tabs.

Fig 12: Isometric View showing the PVC tape strips applied along the length of the longitudinally-cut side walls.

Fig 13: Isometric View of the completed 2-part box (excluding graphics) ready for use Page 3 Detailed Description & Method & Assembly for Producing the Packaging Box The material used is plastic typically) polypropylene extruded-board) it is preferable to use longitudinal square cellular cross-section board figure 1 (1) which is suitable for graphic design printing via large format digital printing machines. This material also has the advantages of: -light weight, stiffness (suitable for supporting/carrying heavy or high-value products), durability (impact/shock resistant and waterproof) and re-use/longevity, while being fully recyclable at end-of-life'.

The 2-part box's developed shape geometries ie: sides/ends and overall length/width are dimensioned oversize figure 2 (2, 3) to allow for the reduction in dimensions due to the creasing/folding /heat-forming process. Typically, the box's internal width/length dimensions are increased by substantially: 2 x (75% of the material thickness) to allow for this compression/reduction of material due to the creasing/folding process. Whereas, the internal height of the sides/end-walls and extended tabs (and the length of the ex- tended tabs) are increased by substantially: 1 x (75% the material thickness) Figure 2 (4). These proportion-ally increased dimensions ensure that the final internal, width/length/height dimensions are achieved when the box is formed into its 3-dimensional shape.

The inherent accuracy of the digital cutting-path X-Y machine allows the box design to be made to close fit-ting dimensions (typically «=-i-1.Smm clearance can easily be achieved between the top and bottom box over the overall length/width dimensions). Tighter tolerances can easily be achieved (±0.145mm on linear di-mensions) hence this ensures the accurate alignment of the extended twin-interlocking tabs and repeatable' assembly of the precise-fitting 3-dimensional box.

Typically, digital cutting-path X-Y machines have an angled cutting blade hence, the knife blade will over-cut into the top surface when profiling out right-angled shapes in plastic cellular board materials. To avoid over-cuts on the printed surface, the digitally printed flat sheet is turned over (while maintaining X-Y align- ment of the printed design's datum co-ordinates relative to the machine's origin co-ordinates) prior to cut-ting out the developed shape) so that the over-cuts are on the un-printed surface and remain hidden inside of the box when formed into its 3-dimensional box shape.

To maintain the box's integrity at the 4-corners, the end walls feature extended tabs (with interlocking twin-angled shapes that engage with the side walls) figure 3 (5) that are subsequently creased/folded (and heat formed) to produce continuous wrap-round radiused corners figure 4 (6)). It is preferable to have short extended interlocking twin-angled tabs' typically, «=SOmm in length, so that any transversely applied forces are principally resisted through the side walls integrated with the bottom/top of the box.

It is preferable to have twin-angled interlocking tab-shapes substantially 90° included angle to en-sure that the wrap-round tabs are kept aligned and level with the side walls (when engaged/interlocked) figure 4 (7).

To maintain a flush surface, the top/bottom surfaces of the box are locally extended beyond the side-wall dotted' crease lines figure 3 (8) so that the top/bottom surfaces remain level with the wrap-round end tabs/side walls, when the box is formed into its 3-dimensional shape (figure 5).

A detailed enhancement is that the extended surface is locally cut-short by a chamfer substantially 45° angle (typically, 2mm x 2mm at the end of the extended surface) which provides a smooth (no sharp edges) transition into the box's 3-dimensional corner radius (see figure 3 (9) and figure 5 (9).

Page 4 The fundamental technique used to produce an accurate straight-sided box, is the application of uniformly applied heat along the external edges of the over-bent sides/end walls so that the thermoplastic material is heat-formed/stress-relieved, thereby ensuring that the sides/end walls remain straight/parallel and at sub-stantially 900 in their new neutral' state.

The digitally printed and cut-out in-the-flat design is placed in a Creasing-jig (with the printed-side face down) so that creases can be accurately made along the sides, end walls and extended tabs figure 6 (iDa, lob, bc). A smooth narrow V-shaped former is used to make the creases (to avoid cutting/scoring the surface) with greater pressure being applied across the grain' to crease the end walls (so that the internal stiffening flutes are fully compressed reducing their natural resistance to folding). The Creasing-jig ensures that the 8-creases are straight/parallel and to the full-depth of the material's thickness; which is important to reduce the resistance to bending and to create an accurate fold-line, so that the final result is an accu-rate close-fitting 3-dimensional box.

The creased developed shape (in-the-flat) is transferred to a Forming-jig which ensures that the sides/end walls are accurately rotated about their Crease lines, while being supported over their length and uniformly heat-formed (e.g. blown hot-air directed by a flattened nozzle) along their external radiused-edges. The side walls are rotated through an angle of substantially 120°-140° (from the horizontal) while heat (substantially 60°C to 80°C) is uniformly applied (externally along the folded edge), allowing the thermo- plastic material to be heat-formed and stress-relieved figure 7 (11). The locally exposed radiused edges en-sure that there is a concentrated heat-forming/stress-relieving effect (at the point of the highest induced stresses) so that the sides/end walls quickly achieve their neutral' straight/parallel substantially 90° right-angled state.

Due to the higher stiffness (ie: resistance to bending/folding) of the end wall, the end wall is first bent through an angle of substantially 45° with heat (typically, 60°C to 80°C) uniformly applied figure 8 (12)) and then a second over-bend substantially 120°-140° from the horizontal with heat (typically, 60°C to 80°C) uni- formly applied, so that the end walls quickly achieve their neutral' straight/parallel substantially 90°right-angled state.

The distinctive rib effect visible along the external formed edge of the end-wall is caused by the creasing of the polypropylene board's internal vertical cellular flutes protruding into the external skin's surface. This ribbed effect becomes more pronounced due to the heat forming process caus-ing local bowing of the skin's surface between the internal cell walls figure 5 (13).

This heat-forming process also eliminates the material's induced stresses due to: the external skin's natural resistance to being stretched through a »=90°, the internal skin's resistance to stretching and the induced stresses due to the over-bending/folding process. A key feature of this stress-relieving process is that the heat-formed sides/end-walls remain straight/parallel (no convex/concave curvature or bowing), which is important for a close-fitting box so that the Top lid can be easily removed/replaced.

The result of this heat-forming/stress relieving and over-bending process is that the sides/end walls reach a neutral (un-stressed state), so that the sides/end walls remain at substantially 90°to the box's top/bottom surface (and straight/parallel) figure 9 (ha, lib), which is essential to form an accurate close-fitting 2-part box.

Once all the side/end walls and extended tabs are at substantially 90°, the interlocking tabs (having also been heat-formed) can be engaged and held flush by the attachment of a internal «=imm thick self-adhe-sive rigid-plastic (e.g. rigid PVC) reinforcement piece positioned centrally over the interlocking tabs figure (12).

Page 5 Other known means of reinforcement are possible, such as the use of low-profile hollow eyelet-rivets to secure the side/end-tabs to the rigid PVC reinforcement pieces thus providing additional protection in tran- sit for heavy/high-value contents and for heavy-duty packaging applications where more protection is de-sirable from shock.

While any internally/externally applied longitudinal loads acting on the end walls (eg: during tran- sit) are resisted by the interlocking tabs, the rigid PVC reinforcement pieces restrain the interlock-ing tabs to remain aligned flush with the side walls.

Where any transverse loads applied to the box side (e.g. during transit) have their longitudinal com-ponents principally resisted by the long side wall integrated with the bottom of the box, and do not subject the short extended tabs' to any damaging shear from the PVC self-adhesive reinforcement pieces positioned over the interlocking tabs.

Once the ends/side walls are all fixed, PVC self-adhesive tape is locally applied to seal the joints over the interlocking tabs and along the top of the extended tabs where they meet the box's top/bottom extended surface figure 11 (14). To maintain a uniform edge to the longitudinally-cut side walls, preferably PVC tape is applied over the edge and along the length of the side walls, forming a smooth and distinctive edge to the box lid/base figure 12 (15). To ensure accurate alignment of the PVC tape, a faint guide-line is digitally printed typically, 5mm above the perimeter edge of the sides/ends walls before the developed shape is cut-out.

The 2-part box is now complete and ready for use and the plastic typically, polypropylene material is suitable for attaching labels such as a self-adhesive Bar-code label (eg: for sequential bar-code numbering), REID tracking tags, anti-counterfeiting tags and other product labelling information Figure 13.

The box (containing its contents) is also suitable for encapsulation in a clear plastic sleeve when be-ing used as a Point-of-sale presentation box prior to retail sale.

The high-accuracy and repeatability in manufacture of the digitally-cut out in-the-flat developed shape means that this design solution is suitable for automated assembly (e.g. using precise automated Creasing, Forming and final assembly jigs) which could have the advantage of achieving the lowest unit cost for vol-ume production typically, for »=1000 off batch sizes.

The principle of operation of the Forming-jig is also suitable for automation to suit volume production methods. A pneumatically operated Forming Jig could allow the sides/ends to be simultaneously over-bent (with a sequenced double bend to suit the stiffer end-walls) and uniformly heat-formed, to achieve the neutral, substantially 900 straight/parallel side/end wall state. The accuracy of the Forming-jig (and the high-accuracy of the cut-out developed shape design) would also allow automated engagement of the ex-tended-twin angled tabs and the automated application of the PVC finishing tape.

Overall, the Automation and simultaneous controlled over-bending and heat-forming method would suit a high through-put of 3-dimensionally formed boxes and consequently the achievement of lower unit costs of production for higher production quantities.

Page 6 Advantages: A key advantage is that the design provides the user/entrepreneur with an alternative low-medium vol-ume, low-cost box solution (that can be made/digitally printed in batch sizes of 1 off to 100's off) without the high up-front costs associated with minimum batch-sizes for lithographically or digitally printed tailored' versions of standard cardboard box designs eg: generic Pizza box designs.

Both lithographic and to a lesser degree digitally printed tailored' versions of standard cardboard box designs, typically require the user to commit/pay for up-front, a minimum quantity (box-cutting/ box printing run) which can be »=1000 off for lithographic printing and «=100 off for digitally printed tailored' cardboard box designs (to achieve an acceptable sliding-scale unit price versus or-der quantity).

The light-weight and stiff design may also suit applications where the product is: heavy, high-value or needs durable (impact resistant) and long-life packaging (that can also be digitally printed/branded presentation box).

The design is scalable and suitable for square (1:1) or higher aspect ratio boxes (ie: 1.5:1) length to width (with the Top box depth at substantially 75% of the box's total height). However, the same design solution can be applied to other shapes e.g. triangular and polygonal shaped 2-part boxes.

The material and standard UV-cured digital printing inks are waterproof/shower proof and non-hazardous.

Alternatively, the box design can be provided without digital graphic-design printing and the surface will still accept adhesive labels.

The deep-sided top lid design provides more protection (effectively double wall-thickness along the sides) and improves structural rigidity.

The deep sided top-lid dimensioned at substantially 75% of the box's total height, allows ergonomic finger/hand access so that the user can easily remove/replace the close-fitting box lid.

The design is suitable for an internal compartmented design to suit multiple storage applications.

The closed' surface does not absorb digital printing inks typically used in the digital UV cured digital print-ing process.

The moisture proof material and box design is adaptable to suit soft or perishable contents.

The high-accuracy of the digitally-cut out in-the-flat' developed shape means that this design solution is suitable for automated assembly and higher volume production »=1000 off batch sizes.

The plastic material typically, polypropylene cellular board is electromagnetically transparent and suitable for internal/external REID tracking tags/product identification and anti-counterfeiting tags/labels that might be desirable when carrying high-value or controlled products.

The material is suitable for security screening by X-Rays.

The box's robustness/stiffness makes it suitable for stacking multiple boxes on top of each other e.g.: on pallets.

Claims (7)

1. Page 7 CLAIMS.1. A re-usable packaging design comprising a developed shape in-the-flat' geometry, and means for creasing the sides/end walls and means for folding the shape and means for setting and fixing the folded shape, that allows the use of light-weight cellular plastic material to produce an accurate close-fitting 2-part box.
2. 2. A re-usable packaging design according to claim 1, in which the plastic material is typically, cellular square cross-section polypropylene board) in which the developed shape design has proportionately increased dimensions to allow for this compression/reduction of material due to the creasing/folding process, and has extended interlocking twin-angled tabs on the box's end-walls that provide a continu-ous radiused corner, when the extended tabs are interlocked with the side-walls, thereby improving the box's structural integrity at the 4-corners.
3. 3. A re-usable packaging design according to claim 2, in which developed shape design in-the-flat' is accu-rately creased to the full-depth of the material's thickness with a smooth V-shaped former to avoid cutting/scoring the surface, and with greater pressure being applied across the grain' to crease the end walls, so that the internal stiffening flutes are fully compressed thereby reducing their natural resist-ance to folding.
4. 4. A re-usable packaging design according to claim 3, in which the digitally printed in-the-flat' design is turned over while maintaining X-Y alignment of the printed design's datum co-ordinates relative to the machine's origin co-ordinates, prior to cutting out the developed shape, so that any over-cuts (due to the cutting-out process) are on the un-printed surface and remain hidden inside of the box when formed into its 3-dimensional box shape.
5. 5. A re-usable packaging design according to claim 4, in which the sides/end walls are first accurately ro- tated about their Crease lines and then over-bent typically, through a 12O014O0 angle from the hori-zontal, while being supported over their length and heat-formed (by heat substantially GOt to 80t) is uniformly applied along the external folded edge, allowing the thermoplastic material to be heat-formed and stress-relieved so that the sides/end walls quickly achieve their neutral' straight/parallel and substantially 9O right-angled free state.
6. 6. A re-usable packaging design according to claim 5, in which rigid plastic typically, rigid PVC self-adhe-sive reinforcement pieces are positioned centrally over the load-carrying interlocking twin-angled tabs thereby holding the engaged tabs flush with the side walls and ensuring the load carrying integrity of the box.
7. 7. A re-usable packaging design according to claim 6, in which plastic tape typically, PVC self-adhesive tape is locally applied to seal the joints over the interlocking tabs and along the top of the extended tabs where they meet the box's top/bottom extended surface and along the length of the side walls, forming a smooth, safe and brand-distinctive edge to the box lid/base.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS1 A reusable packaging design for a 2-part box with a top that fits over a base, each comprised of a blank which incorporates side walls that are shorter than the length of the base and thickness of the end walls, and end walls with tabs having protrusions comprising equally angled divergent edges forming dovetailed means of engagement when, in use, the tabs/protrusions are engaged with correspondingly shaped recesses through the side walls, at a point removed from the corners of the box and backed by planar reinforcement pieces fixed across the engaged joints on the inside of the box.2 A reusable packaging design in accordance with claim 1 in which the blank is constructed and formed from polypropylene cellular board having a cross section of square or rectangular shaped hollow cells.3 A method of forming a reusable packaging design according to claim 1 and claim 2 in which, the fold lines for the sides, end walls and tabs on the blank are created by creasing and permanently deforming the polypropylene cellular board's internal cell walls across and along the grain to the full thickness of the material, overcoming the cellular material's anisotropic properties.r' 4 A method of forming a reusable packaging design according to claim 3 in which, the sides, end walls C,' and tabs of the pre-creased blank are erected to be at right angles to the blank by the action of over-O bending at angles greater than 90 degrees, while heat is uniformly applied along the edge of the bend to create permanently straight, un-bowed, parallel and right angled sides, end walls and tabs. C) (4