EP0835210B1 - Handle for paperboard containers - Google Patents

Description

This invention concerns packaging provided with reinforced handles. Although not limited to such use, the invention has particular advantage in packaging formed from corrugated board incorporating a reinforcing tape.

In previously known corrugated packaging the tape is usually applied on the corrugator during board manufacture, between the fluting and outer liner and usually consists of uniaxially oriented plastics material approximately 11 mm wide. Blanks are die cut from the board so formed in such a way that the tape runs around the periphery of the resulting packs, passing longitudinally through the pack handle, down the pack sides and into the pack base.

It has generally been thought necessary to provide a relatively lengthy anchorage portion of the tape in the material of the blank on either side of the handle. Otherwise, with conventional handle designs, the tape-to-board bond is liable to fail, particularly under shock loads, allowing the tape to pull out of the blank material and the handle to rupture. The need for lengthy tape anchorage portions has hitherto proved a limiting factor in the design of packaging incorporating reinforced handles.

We have discovered that by suitable design of the handle and adjacent blank panels, it is possible to produce a reinforced handle, sufficiently strong for practical purposes, which does not require lengthy reinforcement anchorage portions.

For a significant proportion of the handle load to be transferred into the non-reinforced handle end and non-reinforced panel material, it is necessary that the non-reinforced material does not rupture at the junction between the handle end and panel. For this purpose stress concentrations must be avoided that would otherwise tend to initiate and propagate tearing.

In previously known handle designs, the junction between the panel and the handle is smoothly radiussed to avoid stress concentrations. In some pack designs, the handle end has edges formed by cuts running into the panel and terminating some distance from the panel upper edge. Such handle ends are used for example when the rest of the handle is cut from an upper panel of the package and in use is pulled upwardly out of the plane of the upper panel, hinging the handle ends inwardly. In known pack handle designs of this type, for example as shown in DE-U-7901421, the ends of the cuts are smoothly radiussed and divergent to avoid stress concentrations. This approach is satisfactory when a relatively long reinforcement anchorage portion is used, which will tend to relieve the cut ends of transverse or shear loading. However, where only short anchorage portions are provided, there will be significant transverse and shear loading of the cut ends which serve to concentrate the applied stress locally at the cut tips, leading to tearing. An alternative approach to the relief of stress concentrations is therefore required.

The present invention accordingly provides a reinforced handle having an end portion joined directly to a pack panel in which the reinforcement terminates, the end portion having edges formed by a pair of divergent cuts running into the panel, thereby allowing a substantial proportion of a load applied to the handle to be transferred from the reinforcement to the non-reinforced material of the end portion; characterised in that the cuts terminate in stress relieving apertures formed in the panel. Such apertures are less vulnerable to tearing on transverse and shear loading. The divergent cuts ensure that loading of the handle tends to wedge the end edges against the panel, permitting load transmission between the panel and the end edges. In this way the load carrying capacity of the handle is increased.

To restrain the panel from spreading under the wedging action of the end edges, the panel may be fastened (for example by gluing) to an overlying side of the pack at regions adjacent to the end edges. Such an overlying side may additionally or alternatively be fastened to the panel at regions beyond the ends of the cuts forming the end edges, for load transmission from the pack side into the panel and handle. The panel may therefore constitute a relatively short gluing flap attached to a top panel in the pack. Such an arrangement has not been thought possible previously, as it was considered to provide insufficient reinforcement anchorage length. To provide a greater length of handle for transfer of load from the reinforcement to the non-reinforced handle material, the handle end edges may converge outwardly of the panel boundary.

The invention is further explained with reference to illustrative embodiments shown in the drawings, in which:-

Fig. 1 shows details of a pack blank;

Fig. 2 shows details of the blank of Fig. 1 erected; and

Fig. 3 shows another blank in its entirety.

In Fig. 1 there is shown a handle 10 divided from an end gluing flap 12 and top panel 14 of a pack blank 16 by cuts 18, 20. A reinforcing tape 22 of conventional material is incorporated into the board in the usual manner, but is oriented so as to run through the top panel 14 and gluing panels or flaps 12, rather than through the top panel 14, side panels 24, and a base panel (not shown) as would be the usual arrangement to provide adequate tape end anchorage. The handle 10 has a portion of uniform width defined by parallel parts 18a, 20a of the cuts and a portion of increasing width defined between divergent parts 18b, 20b of the cuts. The widened handle portion lies partly in the top panel 14 and partly in the end gluing flap 12.

The blank has end panels 26 which on erection are folded to overlie the end gluing flap 12, as shown in Fig. 2. These end panels 26 are joined to the side panels 24 by panels 28 which form chamfered corners in the erected pack. However the form of the pack corners is not critical; they could equally be square (not shown) or multi-faceted or rounded (as illustrated in Fig. 3 and further described below). Glue beads or strings 30, 32, 34 are applied to the end gluing flap 12 for securing it to the abutted end panels 26. A small gap is formed in the centre of glue strings 30 and 32, to prevent unsightly glue extrusion between the meeting edges of the panels 26.

The cuts 18, 20 terminate in stress relieving apertures 38, 40 formed in the end gluing flap 12. The glue string 30 is applied to the flap 12 slightly above the apertures 38, 40 so as to cross the cuts 18, 20. The outer portions of the glue string 30 serve to brace the parts of the flap 12 to which they are applied against spreading under the wedging action of the widened portion of the handle 10, by securing those parts to the overlying end panels 26. The glue strings 32 are positioned below the apertures 38, 40 to transfer applied loads from the end gluing flap 12 into the end panels 26, and also to prevent the end panels 26 from being spread apart under the wedging action just discussed.

When the handle 10 is raised from the upper panel 14, those handle parts located in the end gluing flaps 12 will tend to swing inwardly of the pack. Under high shock loading the bond formed by the inner portions of the glue strings 30 could break. However in that case the opposing sides of each of the cuts 18b, 20b adjacent to the apertures 38, 40 will still remain sufficiently coplanar to interfere with one another and provide the necessary wedging action with associated load transfer between the handle and end gluing flaps 12.

The glue strings 34 serve mainly to tack the upper corners of the end panels 26 to the end glue flap 12.

Fig. 3 shows a blank for a 3 x 2 multipack designed to hold six 1 litre soft drink bottles. Upon erection, end panels 26 are folded and secured by glue strings (not shown) to overlie the end gluing flaps 12, forming sloping shoulders conforming to the bottle necks inside the pack. Further end panels 26' are foldably attached to the end panels 26 and side panels 24 and have multiple vertical scores at 41 to form multiple facets conforming to the corner quadrants of the bottles. A base panel 42 is also provided. The handle reinforcement (not shown) is incorporated in the blank material and runs over the distance marked a-a in Fig. 3. It can be seen that this distance is much shorter than the distance b-b over which the reinforcement tape is conventionally provided. However, tests have shown that a handle generally as shown in Fig. 1 has a static breaking strength of 60 kg (approx. 600 N); the handle being 25 mm wide at its central portion, 50 mm wide between the centres of apertures 38 and 40, having a length of 50 mm in the end gluing flap 12 and a tapering length of 40 mm in the top panel 14, the end gluing flap being a minimum size of 90 mm x 90 mm, and the board composition being 140 g/m² kraftliner, 112 g/m² fluting (E), 125 g/m² kraftliner. The pack is designed for 6 x 33 cl beer bottles, weighing approximately 2 kg (20 N) in total, and so the handle strength is clearly adequate, even under the shock loads normally experienced when the pack is being carried. A similar static breaking strength can be achieved with the handle and blank of Fig. 3, again adequate to resist the anticipated static load of around 6 kg (60 N) and shock loads due to carrying.

Claims (6)

1. A reinforced handle (10) having an end portion joined directly to a pack panel (12) in which the reinforcement (22) terminates, the end portion having edges formed by a pair of divergent cuts (18, 20) running into the panel (12), thereby allowing a substantial proportion of a load applied to the handle (10) to be transferred from the reinforcement (22) to the non-reinforced material of the end portion; characterised in that the cuts (18, 20) terminate in stress relieving apertures (38, 40) formed in the panel (12).
2. The handle of claim 1 wherein a side (26) of the pack overlies and is fastened to the panel (12) at regions adjacent to the end portion edges (18, 20), whereby the pack side (26) restrains the panel (12) from spreading under the wedging action of the end portion edges (18, 20).
3. The handle of claim 1 or 2 wherein the end portion edges (18, 20) converge outwards of the panel (12) boundary.
4. The handle of any preceding claim wherein a side (26) of the pack overlies and is fastened to the panel (12) at regions beyond the ends of the cuts for load transmission from the pack side (26) into the panel (12) and handle (10).
5. A pack comprising a reinforced handle (10) as claimed in any preceding claim.
6. A blank erectable to form the pack of claim 5.

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