The present invention relates to a nestable container and in particular but not exclusively to frusto-conical, metal containers that are configured to nest when empty but that are capable of being stacked when filled.

In order to allow frusto-conical containers to be nested so that they can be readily separated the container is usually provided with a nesting bead. This bead is a continuous annular protrusion or projecting flute that is formed around the circumference of the side wall of the container a predetermined distance from its upper rim. The bead facilitates separation of two nested containers by preventing the inner container from nesting completely within the outer as the inner container can only slide into the outer container until its annular bead contacts an upper rim or lip, known as a body curl in this field, of the outer container. This enables the two containers to be separated easily without distortion. However, problems can arise when filled containers of this type, particularly those fabricated from sheet metal with a bead pressed outward from the wall of the container, are stacked one above the other on pallets or similar. Such containers typically weigh between 10 and 12 kilograms when empty and over 200 kilograms when full and may be stacked four or five high. It will be appreciated that when stacked in this way the lowest container bears the weight of those above it, which can be considerable. It has been found that, especially if the weight of the upper container or containers is not distributed evenly, the side wall of a lower, load-bearing container may distort and buckle in the area above the bead and lead to the failure of the container and collapse of the stack. This is because the bead reduces the load-bearing capacity of the side wall of the container above the bead. Factors that have to be taken into account when designing metal containers of this type, therefore, are the thickness of the sheet metal from which the container is fabricated, which is typically rolled sheet steel, and the height of the wall of the container above the bead in order that the container can satisfactorily fulfill the demands that will be placed on it in use, particularly if it is badly handled by the end customer. However, a balance has to be struck because increasing the thickness of the metal from which the container is made to make the container stronger increases both the weight and the cost of the container.

An aim of the present invention is to provide a nestable container, in particular one fabricated from sheet metal that overcomes or substantially mitigates the aforementioned stacking problems.

According to the present invention there is provided a nestable container having a side wall and characterized in that the side wall is provided with a plurality of discrete protrusions spaced around a perimeter of the side wall's outer surface.

Preferably, the protrusions comprise dimples pressed outwardly from the side wall.

Preferably also, the side wall comprises an annular bead or annular bead portions that are located between the lower edges of the protrusions and the body curl of the container and that are shallower than the protrusions.

Preferably also, the container is fabricated from sheet metal that is 0.5mm or more in thickness and advantageously comprises a one-piece or two-piece, frusto-conical drum.

Further preferred but non-essential features of the present invention are described in the dependent claims appended hereto. The present invention will now be described by way of example with reference to the accompanying drawings, in which:-

Fig. 1 is perspective view of a first embodiment of container according to the present invention;

Figs. 2a and 2b are front and side views respectively of a protrusion formed in a side wall of the container as shown in Fig. 1 but to an enlarged scale;

Figs. 3 and 4 are diagrams respectively illustrating two different

orientations of protrusions in the side wall of a container in accordance with the invention; and

Fig. 5 is a perspective view of a second embodiment of container according to the present invention when nested with two similar containers;

A nestable container 1 in accordance with the present invention comprises a side wall 2 that defines a body curl 3, for example provided with a rolled edge or lip as shown in Figs. 1 and 5, and that is connected to a base 4. Such a container 1 may be fabricated from sheet metal, such as rolled sheet steel, that is 0.5mm or more in thickness and is preferably between 0.5 mm and 0.9mm thick. With these techniques, however, it is possible that containers 1 may be fabricated from sheet metal that is below 0.5mm in thickness. The container 1 is preferably in the form of a frusto-conical drum with a body curl 3 defined by a rolled top edge. However, it will be appreciated that the invention is applicable to containers of different nestable shapes and made of different materials.

In the first embodiment of such a container 1 as shown in Fig. 1, the side wall 2 is provided with a plurality of discrete protrusions 5 that are spaced around a perimeter of the side wall's outer surface. The protrusions 5 are preferably identical, evenly spaced and have lower edges 6 located a fixed distance // from the body curl 3, that is the protrusion are all arranged at the same height above the base 4 around the side wall 2. While it is possible for the protrusions to be moulded into the side wall 2 of the container 1 or to comprise buttons or similar items that are individually connected to the container, preferably the container 1 is made in a one piece or two piece construction and the protrusions 5 comprise dimples that have been pressed outwardly from the side wall 2 to a

predetermined depth D, as shown in Fig. 2b. It will be appreciated that this is readily accomplished when the container 1 is made from a pressable material such as sheet metal and is a cost effective method of providing the protrusions 5.

The distance // should be the same for all of the protrusions 5 to ensure even nesting but it will be appreciated that the height H and size of the protrusions 5, in particular the depth £> to which they protrude from the outer surface of the side wall 2 is determined by the size of the container 1 and the angle that the side walls 2 make with the base 4. Preferably, the depth D of each protrusion 5 is at least 4 mm, which is a little less, but still comparable with, that of the annular bead used in conventional containers. Although, the depth D of each protrusion 5 is only limited by the need to stop the nestable containers 1 from being fully nested and becoming stuck.

The shape of each protrusion 5 is preferably one that defines a lower edge 6 which provides a ledge that can bear on the body curl 3 of an outer container 1 when nested rather than being in the form of a point. Apart from this, the shape of the protrusion 5 is not critical and many different shapes are possible.

Preferably, however, each protrusion 5 has a peripheral shape that is

substantially trapezoidal or rectangular and has a cross-sectional profile that is in the shape of half of a teardrop as shown in Figs. 2a and 2b respectively. Such a shape can be readily stamped or pressed into the sheet metal from which the wall 2 of the container 1 may be made. Each such protrusion 5 preferably has a longitudinal axis orientated upwardly with respect to the container 1, that is substantially in line with the longitudinal axis of the container as shown in Fig. 1 and schematically in Fig. 3. However, it is also possible for each protrusion 5 to have its longitudinal axis perpendicular to the longitudinal axis of the container and aligned with a ring around the perimeter of the outer wall surface on which it is formed, as shown schematically in Fig. 4. A second embodiment of container 10 is shown in Fig. 5. This is similar to the first embodiment of container 1 in that a plurality of protrusions 11 is spaced around the perimeter of its side wall 12. However, in addition the side wall 12 comprises an annular bead 13 that is located between lower edges 14 of the protrusions 11 and a body curl 15 of the container 10. The maximum depth of the bead 13 is shallower than the depth D of the protrusions 11. Preferably, the bead 13 intersects the protrusions 11 so that bead portions link the protrusions 11 rather than the bead 13 being located above the protrusions and closer to the body curl 15. Hence, the bead 13 may be continuous or interrupted by the protrusions 11 dependent on the shape and depth of the protrusions 11 at the regions where the two intersect.

As with the protrusions 11, the annular bead 13 is preferably pressed outwardly from the side wall 12 when the container 1 is made from a pressable material such as sheet metal. The bead 13 preferably has a part-circular cross-sectional profile and projects by at least 2 mm at its maximum height from the side wall 12.

It has been found that for two otherwise similar containers fabricated from sheet steel that is 0.7 mm or more in thickness the provision of the protrusions 5 rather than a conventional annular bead enables the container in accordance with the present invention to withstand compression loads when stacked that are between 25% and 40% higher when the loading is even and between 10% and 20% higher when the loading is uneven. The following table shows the maximum compression load that can be withstood by various containers, as indicated, the containers being compressed until failure.

Side wall 0.7 mm 0.8 mm 0.7 mm 0.7 mm

thickness

Container Container Container Container with with with with

6mm bead 6 mm protrusions protrusions &

bead shallow bead Even loading 41.3 kN 49.5 kN 53 kN 58 kN

41.1 kN 47.5 kN 60 kN

Uneven 20.0 kN 22.9 kN 23 kN 25 kN

loading 21.0 kN 21.4 kN

It is thought that containers 1 with discrete protrusions 5 withstand compression loads better than conventional containers with continuous annular beads because the side wall 2 of the container 1 is geometrically uninterrupted and straight between the base and the rim of the container around most of its periphery between the protrusions 5. This increases the load bearing capability of the side wall 2 and therefore of the container 1 as a whole. Also, when the compression load is such that the container 1 starts to yield it has been found that it does not collapse catastrophically in the same way as a conventional container with a continuous annular bead but retains its integrity therefore making such containers much safer to use. Hence, to provide a container in accordance with the invention with the same compression strength as a conventional container, the wall thickness of the container can be reduced, thereby saving materials and cost.

Surprisingly, it has also been found that in containers 10 with a combination of protrusions 5, 11 and a shallow annular bead 13 as described above with reference to Fig, 5 the load bearing capabilities of the container 10 are even better under both even and uneven loads. This may be because the shallow annular bead 13 adds strength to the side wall 12 of the container 10 without weakening the area of side wall above it.

In addition, the use of the protrusions 5, 11 enables the containers 1, 10 to be nested more evenly, with a better nesting definition so that they can be more easily separated when required. Also, the use of the protrusions 5, 11 when pressed outwardly from the side wall 2, 12 of the container 1, 10 does not reduce the height of the container 1, 10 to the same extent as a conventional annular bead. This slightly increases the capacity of the container 1, 10 with consequent cost savings.

Reference Numerals

1 Container - 1 ^st embodiment

2 Side wall

3 Body curl

4 Base

5 Protrusions

6 Lower edge of protrusions

10 Container - 2 ^nd embodiment

11 Protrusions

12 Side wall

13 Annular bead

14 Lower edge

15 Body curl

H Height of protrusions from rim

D Depth of protrusions