Stackable metal can

A stackable container has a peripheral skirt around its base which resiliently fits over a peripheral rim around the lid of a similar container to frictionally engage the container to enable stacking of the containers. When stacked the stack of containers may be processed in a conventional manner.

BACKGROUND OF THE INVENTION 
The invention relates to containers, and finds particular application in 
cans of human and animal food products. 
Canned products are conventionally sold in single cans, or in bulk in 
shrink-wrapped trays of cans. Canned products are sometimes sold in so 
called multipacks of for example 3 or 4 cans, held together by 
shrink-wrapping or board. 
Conventional cans may be able to sit stably one on top of another; however, 
they must be held together, such as by shrink wrapping, while being 
handled. Further, it is not currently possible to stack cans having ring 
pull openings, since a can may bear on a ring pull below, damaging the 
ring pull or causing the line of weakness around the can lid to fail. 
Currently, ring pull cans are transported in trays in single layers. This 
is expensive, particularly for small capacity cans, and means that the 
label on the can is largely obscured if the entire tray is placed on 
retail shelves. 
Cans are generally of standard sizes. Conventionally, multipacks contain 
cans of one size only. Switching production from one size of can to 
another can cause delays in production, as machinery is altered to handle 
the new size of can. 
SUMMARY OF THE INVENTION 
The present invention provides a stackable container, several of which can 
be locked together to form a stable substantially rigid stack which can 
withstand handling during production and transport without being further 
secured. This is provided by a container, such as a can, having a lid 
carrying a substantially peripheral rim, a base, a side wall and a 
generally peripheral skirt around the base, preferably continuously, 
extending away from the container body adapted to resiliently fit over the 
rim of another similar container. 
Preferably, the rim and the skirt are shaped to interlock when the skirt of 
one container is resiliently fitted over the rim of another similar 
container. 
Preferably, the side wall is necked at the lid end so that the rim lies 
inside the perimeter defined by the side wall. Alternatively, the lower 
portion of the container is flared outward, so that the skirt can fit over 
the rim of another container. 
Preferably, the skirt defines a channel on its inward facing side. 
Preferably the container is a metal can, and particularly preferably a two 
piece container, such as a so called draw and redraw (DRD) can, in which 
the side wall and base are of one piece and the lid is of a second piece. 
In this case, the skirt is continuous with the side wall and the base, and 
the rim is the seal between the side wall and the lid. 
In the case of cylindrical containers the skirt of one preferably fits over 
the rim of another with a friction fit as well as a resilient fit to 
prevent relative rotational movement of stacked containers. 
The invention also provides a stack of at least two containers according to 
the invention. 
The invention also provides a method of processing a plurality of 
containers in which the containers are stacked prior to being processed. 
Preferably, the process is adapted for containers of a first height and 
the containers to be processed are of a height or heights less than the 
first height in which the containers to be processed are stacked to a 
height substantially equal to the first height. 
Containers according to the invention can be stacked together immediately 
after being filled and sealed so that subsequent production steps are 
carried out on the stack. This means that several smaller containers, for 
example, two 200 g cans, can be stacked together and processed in the same 
equipment as a single 400 g can, without alteration of the equipment. 
BRIEF DESCRIPTION OF THE DRAWING 
Containers according to the invention can be stacked prior to retail sale 
to allow multipacks to be provided without the need for shrink wrapping or 
other means to secure the containers together. 
The stacks of containers can contain more than one variety of product and 
more than one size of container. 
Different types of container can be stacked together; for example, a can of 
a wet product can be stacked with a container of a dry product. This is of 
particular advantage if the wet and dry products are complementary, such 
as products which are to be mixed together prior to serving. 
If the skirt is a friction fit as well as a resilient fit over the rim, the 
containers of the stack can be labelled in one operation, with separate 
labels which will not subsequently move out of alignment with each other.

DESCRIPTION OF A PREFERRED EMBODIMENT 
FIG. 1 shows part of a top can 10 and a bottom can 12. It will be 
appreciated that the upper end of the top can (not shown) has the 
structure of the upper end of the bottom can and that the lower end of the 
bottom can (not shown) has the structure of the lower end of the top can. 
The cans 10,12 are cylindrical, each having a cylindrical side wall 14,14' 
continuous with a base 16. The top of each can is sealed by a lid 18 
joined to the upper end of the side wall 14' by a sealing rim 20. The rim 
20 is formed by folding together the edge of the lid 18 and the upper edge 
of the side wall 14'. This means that the rim 20 bulges radially outward. 
The lid is a ring pull lid, having circumferential line of weakness 22 
just inside the rim 20. A conventional ring pull 24 is attached to the lid 
18. 
A skirt 26 extends around the circumference of the base 16. It is formed by 
a downward extension 28 of the side wall 14 which doubles back up toward 
the base 16. As it doubles back, the wall approaches the downward 
extension 28 before continuing as the base 16 to define a channel 30 in 
the inward facing side of the skirt 26 and to provide a bulbous nose 32 at 
the lower end of the skirt. 
The upper end of the cans is necked by a shoulder 34 from which extends 
upwards and slightly outwards the sealing rim 20; the free end of the rim 
is of slightly greater diameter than the end joined to the side wall 14' 
and the lid 18. 
To stack the cans 10,12, the top can 10 is placed on the lower can 12 so 
that the bulbous nose 32 of the skirt 26 of one can impinges on the free 
end of the rim of the other can. The cans are urged together and the skirt 
26 resiliently deforms out and over the end of the rim 20. Once the 
bulbous nose 32 of the skirt has passed over the free end 20 of the rim, 
it resumes its previous configuration to clip over the rim 20, locking the 
cans together. The rim 20 of the bottom can 12 interlocks with the channel 
30 in the skirt 26 of the top can 10; this helps secure the cans together. 
The base 16 of the top can 10 rests on the free end of the rim 20 and the 
bottom of the skirt 26 of the top can rests on the shoulder 34 of the 
bottom can 12. In an alternative embodiment, the rim 20 is high enough for 
the base 16 to rest on the rim of the can 12 below, but the skirt 26 is 
not long enough to reach as far as the shoulder 34 of the can 12 below. In 
another embodiment, the skirt 26 of the top can 10 is long enough to rest 
on the shoulder 34 of the can 12 below, but the rim 20 is insufficiently 
high for the base 16 of the top can 10 to rest on it. In the case of ring 
pull cans, it is important that the base 16 of the top can does not bear 
on the ring pull 24 of the bottom cans, since this could cause the line of 
weakness 22 on the lid 18 to fail. 
The dimensions and positions of the skirt 26 and rim 20 are chosen so that 
they are a friction fit as well as a resilient fit. 
FIG. 2 shows a top can 40 and a bottom can 42 according to a second 
embodiment of the invention. In most respects, the cans 40,42 are similar 
to the cans 10,12 of the first embodiment shown in FIG. 1, and like 
reference numerals have been used to represent like parts. However, the 
side walls 44 of the can is flared out at its lower end by a shoulder 46. 
The skirt 48 is formed by a downward extension of the side wall 44 from 
the outer, lower end of the shoulder 46. It is similar to the skirt 26 of 
the embodiment of FIG. 1, but is shaped to curve around the rim 20 of a 
can and rest on the upper side wall 44', immediately below the rim. 
Once clipped together, several cans can be picked up together by picking up 
the top can. A sharp tug at an angle to the principal axis of the cans 
will separate them. 
It is envisaged that the cans will be stacked shortly after filling and 
sealing, so that they are further processed as a stack. Normally, several 
small cans, such as two 200 g cans or four 100 g cans, will be stacked and 
processed as if they were a single 400 g can. At this stage, the cans will 
normally be of a single variety of product. 
It should be noted that as the stack passes through a retort, water may 
collect in the spaces between the cans. It may therefore be necessary to 
separate the cans forming the stacks and dry them in a conventional 
manner. New stacks can then be made which need not have the same 
constitution as the previous stacks. 
The stacks of cans can be labelled in a single operation, separate labels 
being applied to each can in a stack. Since the cans are a friction fit 
with each other, there is no relative rotation of cans within a stack; 
thus, the labels remain in the alignment in which they are applied. This 
has particular advantage when a stack is composed of different varieties 
of one type of product; similar labels can be used for each variety, the 
corresponding parts of each label being in and remaining in alignment from 
can to can within the stack. 
It will be seen that the present invention provides a can which has 
significant advantages in ease of processing, transport and at retail sale 
compared with conventional cans.