The present invention relates to stacking containers and to the stacking of containers.

There are many types of containers which are formed into stacks during use. For instance, delivery containers used to deliver goods to retail premises may be in stacks while in transit.

The present invention seeks to make improvements in and relating to the stacking of containers. It is to be understood that throughout this specification, the terms "stack", "stacked" etc. are used in their broad sense to cover any stack or stack-like arrangement, including formations in which containers are wholly or partly nested inside each other.

The invention provides a securing member for use with stackable containers, the member comprising first and second container engaging portions connected together, each container engaging portion being so formed as to be selectively engageable and disengageable with a container in a respective stack of containers, whereby two stacks of containers may be secured together.

The securing member may comprise two limbs, which may be generally parallel, each of which carries a container engaging portion. The limbs may be connected together to form a generally U-shaped member. The limbs may be different in length.

The or each container engaging portion is preferably engageable with an aperture or recess in a container. At least one container engaging portion may comprise a hook formation for hooking engagement past a surface of a container. At least one container engaging portion may comprise at least one barb formation for engagement with a container. The or each container engaging formation may comprise a guide surface which, in use, guides the container engaging portion into an aperture or recess in a container, and may comprise a retention surface which, in use, engages a surface of the container

to prevent withdrawal from the aperture or recess. The securing member may comprise at least one resiliently deformable portion which is deformable to allow a container engaging portion to engage a container or be disengaged therefrom.

The container engaging portions are preferably connected together by a resiliently deformable portion. The resiliently deformable portion is preferably elongate and deformable by twisting.

The invention also provides a method of stacking containers, in which at least one container from one of two adjacent stacks of containers is secured to a container in the other stack.

The containers are preferably secured by means of a securing member as aforesaid.

The invention also provides a container system comprising a plurality of containers which may be formed into stacks, and at least one securing member as aforesaid.

Each container may comprise an aperture or recess for engagement with a container engaging portion of a securing member.

An embodiment of the present invention will now be described in more detail, by way of example only, and with reference to the drawings in which:

Fig.l is a front elevation of a securing member according to the invention;

Fig. 2 is a side elevation of the member of Fig. 1;

Fig. 3 is a highly schematic elevation, showing the member of Figs. 1 and 2 in use; and

Fig. 4 is a partial perspective view showing the member in use.

The securing member 10 shown in Figs. 1 and 2 is for use with stackable containers, as will be described. The member 10 comprises first and second container engaging portions shown generally at 12 A, 12B, connected together generally at 14. Each container engaging portion 12 is formed to be selectively engageable and disengageable with a container in a respective stack of containers, whereby two stacks of containers may be secured together as will be described. Each stack could be attached to more than one other stack, so that any number of stacks can be connected together, for increased stability.

In more detail, the member 10 is generally U-shaped, having two limbs 16A, 16B which are generally parallel in this example, but could be at other angles, according to the design of the container with which they are to be used. Each limb 16 carries a container engaging portion 12 at its free end and is connected to a body 18 at its other end. The body 18 has a flared profile (Fig.2) to provide finger grips. Alternatively, the body 18 may include a ribbed portion (not shown) for providing finger grips.

The container engaging portion 12A has the general form of an arrowhead, having a relatively narrow end face 22 behind which the arrowhead widens to provide lead-in surfaces 24. Generally parallel side faces 26 extend back from the lead-in surfaces 24 to shoulders 28, at which points the outline of the engaging portion 12 A turns in to meet the limb 16 A. It is to be noted that the shoulder surfaces 32 are gently curved between the shoulders 28 and the sides of the limb 16A. However, an alternative design would use surfaces 32 which meet the sides of the limb 16A at a concave angle.

The container engaging portion 12B has the general form of a hook, having a generally triangular projection 40 to one side of the line of the limb 16B, which turns away from the limb 16A at an elbow 42 near the portion 12B. The hook 40 has a lead-in surfaces 44 at its tip, and a shoulder 46, at which point the outline of the hook 40 turns in to meet the limb 16B.

The securing member is made of resilient material, preferably an injection-moulded plastics material. In consequence, the limbs 16 are resiliently deformable by twisting and/or bending.

The securing member 10 can be used in the manner illustrated in Figs. 3 or 4. These figures show part of two containers 50 which each have side walls 52 extending up from a base (not shown). Stacking bars (or flaps, bales, arms or similar structures) 56 are mounted near the top of the side walls 52 to support the base of another container 50 thereby forming two stacks alongside each other. In the situation shown in the drawings, the two containers 50 are not at the same height. For instance, adjacent stacks may incorporate different mixtures of containers of different heights. This can result in a height difference at the top of the stack. The different lengths of the limbs 12 A, 12B allows for this, as will be described, but the member 10 can also be used when adjacent containers are at the same height.

The bars 56 are mounted on the walls 52 by means which do not themselves form part of the invention. However, the bars 56 have end portions 58 which reach down into recesses 60 formed between the side walls 52 and secondary walls 62. The recesses 60 are open beneath, at 64. The recesses 60 are generally rectangular in plan, the gap shown in Fig. 3 representing the narrow axis of the recess 60. The two ends of each bar 56 are supported by similar structures which are mirror images of each other. Consequently, when two container stacks are formed alongside each other, the secondary walls 62 of two containers 50 are next to each other, but displaced vertically, as shown in Fig- 3.

The two stacks can now be secured together by pushing the two limbs 16 of the member 10 down into respective recesses 60. In the situation illustrated in Fig. 3, the arrowhead 12A or the hook 12B will first enter the respective recess 60, depending on whether the vertical separation of the walls 62 is greater or less than the separation of the arrowhead and hook.

As the arrowhead 12A enters the respective recess 60, the limb 16A will twist as the arrowhead 12 A is forced in. Eventually, the arrowhead 12A will reach the bottom 64 whereupon the limb 16A springs back to untwist. The arrowhead then forms a barb whose surfaces 32 would engage the mouth of the recess 60 so that the securing member 10 cannot thereafter be removed merely by lifting in the vertical direction. This engagement is expected to be adequate even with curved surfaces 32, but could be enhanced by the concavity of the alternative design mentioned above.

As the hook 12B enters the respective recess 60, the limb 16B will twist as the hook 12 B is forced down through the recess 60. Eventually, the hook 12B will clear the bottom 64 of the recess and hook under it as the Limb 16B snaps back to an untwisted position.

It should be appreciated that the precise order of events is governed by the dimensions of the member 10 and the relative positions of the two containers. Depending on these factors, either engaging portion 12A.12B may be first to enter the respective recess 60, and the second to enter may do so before or after the first has emerged clear of the bottom 64 of the respective recess 60.

Removal of the member 10 is achieved by gripping the body 18 and twisting it about a generally vertical axis. This causes distortion of the member 10 by twisting the limbs 16. If the member 10 is twisted sufficiently, the arrowhead 12A and hook 12B come into alignment with the respective recess 60, allowing the member 10 to be withdrawn. Again, the precise order of events will depend on the dimensions of the member 10 and the relative positions of the two containers.

Although the curve of the surfaces 32 is considered adequate to retain the clip when relaxed, the surfaces 32 can act as guide surfaces after twisting the member 10, to assist in withdrawing the arrowhead from the aperture. It is expected that the curved surfaces could even be designed to assist withdrawal

sufficiently to cause adequate twisting of the limbs 16 by pulling without manual twisting, while nevertheless adequately securing stacks together during use. Similarly, the detailed shapes of the surfaces of the hook 12B are chosen to ensure adequate security, while allowing removal when required.

Thus, with the member 10 in position, there is a reasonably secure attachment between the two adjacent containers, sufficient to hold the stacks together during normal handling, such as when loading stacks onto a vehicle by fork truck. Securing together the two adjacent stacks reduces the risk of either stack toppling over. However, the members 10 can be readily removed by hand (as has been described) when the stacks are no longer required to be attached.

It is not envisaged that a member 10 would be used at each level in the stack, but only in sufficient numbers to ensure adequate security, and perhaps only at the top of a stack. Thus, a complete container system would comprise a large plurality of containers but probably a much smaller number of securing members.

In the arrangement just described, the engaging portions 12 pass through the bottom of the recess 50. Alternatively, they could snap into apertures formed in the side walls of the recesses 50. It is envisaged that containers could be attached side-by-side, as shown in Fig. 4, or end-to-end, or even side-to-end, depending on the design of the members and the containers.

In alternative versions, as has been said, the container engaging portions 12 could be shaped differently, for instance by changing the angles and shapes of the side faces 26 and shoulders 28. Some designs could allow removal of the member 10 by simply pulling it vertically, without manual twisting, but it may be more desirable to require a twisting action for release, to reduce the risk of a member being removed accidentally. For instance, if a stack of heavily loaded containers started to topple, causing one container to move upwardly relative to the container in an adjacent stack, a member might become disconnected from one or other container if twisting was not required. By contrast, if twisting is

required, it is unlikely that the member 10 can be inadvertently released during normal use. Thus, movement of a stack which begins to topple will tend to be resisted.

Securing members according to the invention are expected to be particularly useful in situations where containers are being transported in stacks, there being several stacks on a single support, such as a pallet, trolley, etc. In these situations, unsecured stacks of containers are likely to topple because of e.g. vibration. Securing the stacks together as has been described makes the stacks more secure and may allow higher stacks to be used, with consequent economies, but is easily and cheaply achieved.

It is to be understood that very many variations and modifications may be made to the member described above and shown in the drawings, without departing from the scope of the invention. In particular, the designs of the barbs 12 may change. The overall design will depend on the design of the container with which the member is to be used, and the degree of security required. The container geometry indicated in Fig. 3 is highly schematic and serves only as an example. Very many variations on this general container geometry are known to the man skilled in the art.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.