AU694791B2 - Improvements relating to the stacking of containers - Google Patents

Description

Regulation 3,2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

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Name of Applicant: Omicron Pty. Ltd.

Actual Inventor(s): George MINGIN Address for Service: DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Steet, Melbourne, 3000.

Invention Title: Improvements Relating to the Stacking of Containers Details of Associated Provisional Application(s): No(s): PM8414/94 filed 26 September 1994 The following statement is a full description of this invention, including the best method of performing it known to me/us: 1- Si I IMPROVEMENTS RELATING TO THE STACKING OF CONTAINERS This invention relates generally to the stacking of containers and provides in particular a stackable container incorporating a feature which facilitates the stability of a stack of the containers. The invention has particular but by no means exclusive application to hand-held twin-cavity trays for food products.

Twin cavity trays of the aforementioned type are typically integrally thermoformed or injection moulded in a suitable polymer material to define a generally square rim with large radius corners and an off-diagonal web separating two cavities. These cavities are :fi' "defined by dependent thin wall structures of rounded triangular form in plan, and are usually of different sizes. To allow stacking of the trays for delivery to food product manufacturers, the cavity walls are tapered downwardly inwardly. To facilitate ready separation of the trays as they are dropped at high speed one-by-one from these stacks onto the conveyors of filling machinery, the trays typically have multiple stacking lugs or ledges which are formed integrally about the rounded corners of the triangular wall structures a few millimetres below the rim.

Experience with twin-cavity trays has revealed a significant problem with their transport and handling as a stack. It is found that stacked groups of trays are liable to collapse in S 0,C sequence along a comer of a stack as the successive stacking l'g, uf ledges about these corners slip inside the cavity below, instead of remaining seated on the underlying rim.

When this phenomenon occurs, the only practical reaction is to discard the collapsed group of stacked containers.

It is therefore an object of the invention to at least reduce the incidence of this problem.

The present inventor has observed that the problem discussed above essentially arises from the relatively steep inclination of the outside cavity walls of the tray, for example of the order of 13" in one product. This angle is determined by considerations including the functioning of filling and handling machinery but does allow successive trays to slip sideways sufficiently for the stacking lug to drop down into the underlying cavity. The 95083 l,p:opean,omcron.cap, I P:\OPEROPHH 389.95.SPE 26/98 -2inventor has further realised that the problem under discussion usually only occurs in two of the four corners of a tray stack, ie the corners at either end of the off-diagonal web of the rim. It appears that this is because transverse slippage at the other corners is adequately limited by the more steeply inclined cavity walls adjacent the web, for example of the order of 2 to 30 to the vertical. From a broad view, in the present context therefore, the invention entails the limitation of transverse slippage in the direction parallel to these adjacent inner cavity walls. The invention does of course have much broader application.

The invention therefore provides a container including: 10 means defining a floor and a plurality of side walls about a space such that when the floor rests on a horizontal surface, the side walls are inclined to the vertical; rim means about the side walls; and one or more stacking formations arranged on or adjacent said side walls to cooperate with said rim means of an underlying similar container to define a spacing between said 3 S S 15 containers when the containers are stacked with said floor- and wall -defining means in the space of the underlying similar container; wherein means is provided on one or more of said side walis which cooperates with corresponding means in adjacent similar containers of a stack to limit transverse relative movement of the containers sufficiently to maintain said cooperation between the stacking formations and said rim, means, said cooperating means comprising an integral projection formed in the side wall(s) and being hollow, said projection and hollow each defining a respective upright side and being shaped to be accommodated in and to accommodate, respectively, the hollow and the projection of respective adjacent containers in the stack.

Preferably, said projection/hollow comprises a rib/channel or lug/recess formed in a side wall, eg centrally on the side wall, the rib/channel or lug/recess having spaced sides and a front which are preferably inclined to the vertical by between 1 and 30 to facilitate separation when forming or moulding the container and to facilitate stacking.

Where the container is a twin-cavity tray or container with thin wall structures defining two unequal cavities of generally rounded triangular profile, the projection is preferably formed at the centre of that side wall of the larger cavity which is adjacent the smaller cavity.

PA\OPER\PHH3o389-95.SP -2/6/98 -3unequal cavities of generally rounded triangular profile, the projection is preferably formed at the centre of that side wall of the larger cavity which is adjacent the smaller cavity.

Alternatively, a respective projection/hollow may be provided at each end corner of one of the side walls.

Preferably, the projection projects inwardly into the space.

r The invention will now be further described, by way of example only, with reference to the Ct o 10 accompanying drawings, in which: Figure 1 is a perspective view from above of a twin-cavity tray according to an C embodiment of the invention; :Figure 2 is a plan view of the tray; Figure 3 is a cut-away view of the tray providing a side view of the stacking alignment 15 rib; and i Figure 4 is an underneath view of the tray.

it C" The illustrated tray 10 is typically thermoformed in a suitable polymer material to define a t C rim 12 of generally square configuration with large radius comers 14, and a pair of dependent thin wall structures 16,18 which define side walls and floors for a larger cavity 17 and a smaller cavity 19 of rounded triangular form in plan. Rim 12 is of uniform width along two sides of the respective cavities and at opposite corners 14a,14b of the tray. The wall structures 16,18 and cavities 17,19 are separated by off-diagonal web portion 20 of rim 12.

Rim 12 further includes a longitudinal shallow rib 22 which extends along web 20. This rib 22 strengthens web 20 and defines a web hinge. Shallow upstanding flat lips 24,25 encircle the upper edges of cavities 17,19.

The side walls of cavities 17,19 which are remote from web 20, that is outer side walls 30,31 of cavity 17 and 32,33 of cavity 19, together with the three comers of each cavity are inclined at about 13° to the vertical when the respective flat floors 2 6 7 of the cavities are on a horizontal surface. The adjacent inner side walls 34,35 of the respective f^ n

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-4cavities are substantially steeper, being inclined at about 2 to 50 to the vertical. The inclinations facilitate separation of the trays during their formation and of course allow the trays to be stacked. The specific inclinations relate to the parameters of filling and handling machinery. To maintain the trays at a set vertical separation when they are stacked, the four outer comers of the side wall structures have crescent-shaped outwardly projecting stacking lugs or ledges 40 which are intended to rest upon underlying rim 12 of the next adjacent tray. These lugs 40 define recesses at the comers of the cavities.

The inventor has found that at comers 14a, 14b of the tray remote from web 20, these lugs or ledges 40 are effective in maintaining tray separation due to the action of the steep inner side walls 34,35 in preventing transverse slippage of stacked trays. However, with the other comers 14c,14d there is a significant incidence of stack collapse in which stacking lugs or ledges 40 drop into the underlying larger cavity 17. 1 To overcome this problem in this embodiment, the inner side wall 34 of large cavity 17 is formed at its centre with a vertically extending stacking alignment rib 50. This rib is thin-walled and thus forms a channel 50' on the underside of the tray. Rib 50' defines three principal wall portions a front wall 51 generally aligned with but slightly tapered downwardly and inwardly towards wall 34, and two subsidiary side walls 52,53 which project normally to side wall 34 in a horizontal plane but are inclined at about 2 to 30 to the vertical, preferably about Front wall 51 of rib 50 is inclined very slightly to the vertical, say about 1 to The walls 51,52,53 of rib 50/channel .intersect at relatively smaller radius edges 54 but merge into side wall 34 and the curved bottom comer of the cavity with relatively large radius comers such as 56,57. The top of the alignment rib 50 may be flat but is preferably some form of domed structure 58.

When successive containers 10 are in a stack, with wall structures 16, 18 within the cavities 17,19 of an underlying tray, and stacking lugs or ledges 40 at rest on the underlying rib 12, the channel 50' extends about the rib 50 of the underlying tray and the sides 52,53 of these respective parts cooperate to minimise slippage of the containers parallel to rib 20 and side walls 34,35. This slippage is sufficient to prevent either of the stacking lugs 40 at comers 14c,14d slipping off the rim 12 into the larger cavity 17.

95083 l,p:Aoprgjn,omicron.cap,4 It will of course be appreciated that the alignment maintaining wall portions 52,53 may be provided in any of a number of ways. For example, rib 50/channel 50' may be on any suitable side wall of either cavity and may be a simple lug and recess rather than an extended rib or channel. Moreover, wall portions 52,53 might be provided by separate formations at opposite ends of side wall 34 emergent from the corners of the cavity wall structure.

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CCC C 44CC C C C *i C The described arrangement has been advanced merely by way of explanation and many modifications may be made thereto without departing from the spirit and scope of the invention which includes every novel feature and combination of novel features herein disclosed.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

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Claims (8)

1. A container including: means defining a floor and a plurality of side walls about a space such that when the floor rests on a horizontal surface, the side walls are inclined to the vertical; rim means about the side walls; and one or more stacking formations arranged on or adjacent said side walls to cooperate with said rim means of an underlying similar container to define a spacing between said containers when the containers are stacked with said floor- and wall -defining means in the space of the underlying similar container; wherein means is provided on one or more of said side walls which cooperates with corresponding means in adjacent similar containers of a stack to lim~it transverse relative movement of the containers sufficiently to maintain said cooperation between the stacking 15 formations and said rim means, said cooperating means comprising an integral projection in the side wail(s) and being hollow, said projection and hollow each defining a respective upright side and being shaped to be accommodated in and to accommodate, respectively, the hollow and the projection of respective adjacent containers in the stack.

2. A container according to claim 1 wherein a respective projection/hollow is provided at each end corner of one of the side walls.

3. A container according to claim 1. wherein said projection/hollow comprises a lug/recess having spaced upright sides and a front.

4. A container according to claim 1 wherein said projection/hollow comprises a rib/channel having spaced upright sides and a front.

A container according to claim 3 or claim 4 wherein said upright sides and front are inclined by between 1 and 3' to the vertical.

6. A container according to any one of claims 3 to 5 wherein said projection is disposed I_ P\OPER\PHH\30389-95.SPE -2/6/98 -7- centrally of the associated side wall.

7. A container according to claim 6 wherein said container is a twin-cavity tray or container with thin wall structures defining two unequal cavities of generally rounded triangular profile, and wherein the projection is formed at the centre of that side wall of the larger cavity which is adjacent the smaller cavity.

8. A container according to any one of the preceding claims wherein the projection projects inwardly into the space. S9. A twin cavity tray or container substantially as hereinbefore described with reference to the accompanying drawings. DATED this 2nd day of June 1998 t' 15 Omicron Pty Ltd By DAVIES COLLISON CAVE Patent Attorneys for the applicant c i c c 8 ABSTRACT A container includes means defining a floor and one or more side walls about a space such that when the floor rests on a horizontal surface, the side wall(s) are inclined to the vertical. Rim means is arranged about the side wall(s) and one or more stacking formations are arranged on or adjacent the side wall(s) to cooperate with the rim means to define a spacing between successive containers when the containers are stacked with the wall means in the space of an underlying similar container. One or more of the side wall(s) is provided with means which cooperate in successive containers of a stack to limit transverse relative movement of successive containers sufficiently to maintain the aforementioned cooperation between the stacking formations and the rim means. lee *I:pt Sct t r t