EP0090639B1

EP0090639B1 - Nestable containers

Info

Publication number: EP0090639B1
Application number: EP19830301752
Authority: EP
Inventors: David Tomkins; Oswald V. D'silva
Original assignee: Lin Pac Plastic Containers Ltd
Current assignee: Lin Pac Plastic Containers Ltd
Priority date: 1982-03-29
Filing date: 1983-03-29
Publication date: 1987-03-25
Also published as: EP0090639A3; DE3370464D1; EP0090639A2

Description

Thin-walled plastics cups and other containers are now commonplace. For transport, e.g. from a place of manufacture to a place of use, such cups or other containers are nested together to form stacks. The cups or other containers in such nested stacks tend to jam together and in an attempt to overcome this each cup or other container has been provided with stacking means. Such stacking means comprises an internal upwardly-facing surface and a stacking surface. The surfaces are located in planes normal to the central axis of the cup or other container. In an upright stack the stacking surface of each intermediate cup or other container rests on the internal upwardly-facing surface of the cup or other container below, whilst its internal surface supports the external surface of the cup above. Such stacking means are sufficient to ensure that the cups or other containers do not jam together when a stack is formed and handled carefully. However, when such a stack is subject to an axial shock load by being jolted, for example when a case of such stacks is unloaded from a vehicle or is subjected to vibration during transport; the outer edge of the external stacking surface of one cup or other container overrides the inner edge of the internal upwardly-facing surface of the cup or other container below. This jams the two cups or other containers together tightly and this presents a major problem when the two cups or other containers are to be separated by automatic machinery. This problem is particularly significant with a stack of cups which is packaged with ingredients in each of the cups. Such cups are known as ingredient cups and typically the ingredient is a powder which will provide a beverage when an individual cup is removed from the stack and filled with hot water. The additional weight of the ingredient means that the weight of each stack is greater than the weight of a corresponding stack of empty cups. Thus stacks of ingredient cups are more prone to jamming during transport or when they are unloaded from a vehicle.
Such a construction is shown in US-A-3288340. The known construction comprises a nestable cup or other container with a bottom and a side wall, and including stacking means comprising a circumferential shoulder having an internal, upwardly-facing surface inclined in a direction downwards and outwards and terminating at an acute angled convex corner, the surface being either continuous or interrupted to form castellations, so that, when a plurality of identical cups or other containers are assembled together into an upright stack, the corner of the cup or other container makes localised contact with a stacking surface of the cup or other container above, the corner engaging the stacking surface away from its edge. The above-mentioned disadvantages can be mitigated by the solution defined in claims 1 and 5.
Any vertical shock loading applied to a stack of such cups or other containers is cushioned by resilient deformation of the stacking surface. Further, since the internal upwardly-facing shoulder is inclined outwards and downwards, after the stacking surface has been deformed, both shoulder and stacking surface are inclined outwards and downwards and therefore axial shock loading between these surfaces generates forces tending to expand the stacking surface and contract the internal shoulder, so resisting the external shoulder overriding the internal shoulder.
The internal upwardly facing shoulder may be castellated with alternate lands being inclined. In this way the lower edge of the inclined lands merge with the lands that lie in a plane normal to the axis of the cup or other container and thus the stacking surface of the cup above rests on the acute-angled convex corners at the upper ends of the inclined lands. When a stack of such cups is subjected to axial shock loads the stacking surface is deformed only in the areas in engagement with the upper ends of the inclined lands. This deformation absorbs the shock loading and then the lands lying in a plane normal to the axis of the cup or other container are engaged by the remainder of the stacking surface of the cup or other container above and this provides a positive stop. Again the deformed parts of the stacking surface of the cup or other container above and the inclined lands generate forces tending to expand the stacking surface so resisting the stacking surface overriding the internal upwardly facing shoulder.
The internal upwardly facing shoulders of the stacking means may be located anywhere along the side wall of the cup or other container. In ingredient cups, the internal upwardly facing shoulder is usually located at and used to define the top of the ingredient pocket in the cup or other container. In this case it is preferred that the inner upwardly facing shoulder is formed by a continuous annular downwardly and outwardly inclined surface. With such a construction a continuous seal is provided all around between the upper corner of this surface and the stacking surface of the cup or other container above so holding the ingredient in its pocket and preventing its migration during transport and handling.
According to this invention the resistance to the overriding of the stacking means of such cups is increased still further by modifying the side wall of the cups or other containers to include a plurality of circumferentially spaced externally projecting nibs having bases inclined downwards and outwards around the stacking means and arranged so that when a plurality of identical cups or other containers are nested to form an upright stack, the nibs on the upper cup or container are very close to, or touch, the interior of the side wall of the next cup below.
Some of any axial shock loading applied to the stack is absorbed by resilient deformation of the side wall where it is engaged by the nibs and also the nibs help in centralising the cups or other containers in the stack so that there is the optimum overlap between the stacking means of adjacent cups or other containers. Since the base of each nib is also inclined downwardly and outwardly this helps increase the digging in effect of the nib into the side wall of the cup or other container below and so increases its resistance to overriding of the stacking means.
Whilst these cups and other containers are specifically intended to be used with thin-walled plastic cups, they can also be applied to all manner of thin-walled, thick-walled, multi-walled, lockable, jamming, non-lockable and stackable containers, made of a variety of materials such as plastics or paper, using a variety of manufacturing techniques provided that the downwardly facing shoulders of the stacking means have some inherent resilience so that they can deform to absorb any axial shock loading.
Typically when made from a plastics material the cups or other containers are made from high impact polystyrene, other grades of polystyrene, polypropylene, or polyvinyl chloride. In each case the shape of the cup is determined by the shape of the cavity in the female mould, which operates as a rigid unit apart from an ejector in its base. The deformation of a heated sheet of plastics is started mechanically by a plug, and is finished by the admission of air under pressure to the interior of a pre-form created by the plug. There is no use of vacuum and thus the apparatus is simple.
Preferably the corners of the mould which produce the sharp acute-angled corner along the upper edge of the internal upwardly facing shoulder has a radius in cross section not exceeding 0.25 mm, and the corners in the mould which produces the other corners at the edges of the upwardly and downwardly facing shoulders also have a radius in cross section not exceeding 0.25 mm.
Preferably the surface of the mould which forms the inner upwardly facing shoulder is inclined downwards and outwards at an angle of 7° to the horizontal. This angle may be varied within the range 5° to 10° to the horizontal.
Particular examples of plastics cups in accordance with this invention will now be described and contrasted with the prior art with reference to the accompanying drawings; in which:

Figure 1 is a sectional elevation through two conventional ingredient cups nested together;
Figure 2 is a sectional elevation through two conventional nested ingredient cups which have become jammed together;
Figure 3 is a sectional elevation through one ideal form of ingredient cup;
Figure 4 is a sectional elevation through a first example;
Figure 5 is a section through two of the first example of ingredient cups;
Figure 6 is a section through two of the first example of ingredient cups nested together illustrating the deformation of the cups caused by axial loading;
Figure 7 is a perspective view of a second example of cups;
Figure 8 is a section through two cups in accordance with the second example nested together;
Figure 9 is a section through two of the second example of cups nested together and subjected to an axial loading;
Figure 10 is a sectioned perspective view of the first example of cups in accordance with this invention showing all of its features;
Figure 11 is a section through two of the cups as shown in Figure 10 nested together; and,
Figure 12 is a section showing a modification.
Figure 1 shows two known nested ingredient cups 1A and 1B under normal conditions. Each comprises a side wall 2, a base 3 and an annular shoulder 4 extending in a plane normal to the axis of the cup. The bottom 3 of cup 1A sits on the inner upwardly-facing surface of shoulder 4 of cup 1 B. An ingredient pocket 6 is formed between the cups 1A and 1B and in use, these contain a beverage powder 7.
Figure 2 shows the effect of an excessive axial load on a nested stack of such cups. The external corner around the periphery of the bottom 3 of the cup 1A has overridden the internal corner around the periphery of the shoulder 4 of cup 1 B and so jammed itself into the ingredient pocket 6 of cup 1B.

The resistance to jamming of such a stack of cups to an axial shock is a result of the relationship between the degree of overlap between the shoulder 4 and the bottom 3 of the next cup in the stack. If the degree of overlap shown as X in Figure 3 is made sufficiently large and the corners 8, 9 and 10 made sufficiently sharp, then this problem can be overcome. To obtain maximum benefit from the overlap X the corner 10 needs to be sharp on the outside of the cup whilst the corner 9 needs to be sharp on the inside of the cup. The effectiveness of the overlap also depends upon the cups being located concentrically in the stack by co-operation between the corner 10 and the inside of the corner 8. However, to produce cups of this nature using standard pressure-forming techniques is virtually impossible because of the problem of ensuring sharp corners and the subsequent ejection of the cups from a mould in which they are formed. In the past, this has led to the development of complicated and expensive techniques such as vacuum assisted pressure-forming and drop-based tooling. Figure 4 shows a cup in accordance with this invention formed as an ingredient cup 11. The annular shoulder 5 between the corners 8 and 9 has a downward and outward slope. Figure 5 shows a stack of two such cups 11A and 11 B and nested together. The sharp acute-angled corner 9 at the inside of the downwardly and outwardly inclined annular shoulder 5 of the cup 11 B engages the bottom 3 of the cup 11A away from its outer corner 10. A circular line contact is established between the two cups to define the ingredient pocket 6. The shoulder 5 is inclined at 7° to a plane normal to the axis of the cups.
When an axial load is applied to a stack of such cups an upward force is transmitted by the corner 9 of cup 11B to the bottom 3 of cup 11A away from the corner 10. As the load is increased the upward force causes an upwards distortion in the bottom 3 of cup 11A until the corner 10 engages the face of the inclined shoulder 5. Thus, the first thing that happens in the event of a stack of such cups being subjected to an axial load is that the bottom 3 distorts to absorb some of the axial load. Any further increase in the axial load involves forces being transmitted over zones of the bottom 3 of the cup 11A and the inclined shoulder 5 of the cup 11 B. These zones are in face to face inter-engagement as shown in Figure 6 and each has a significant extent in the radial direction. Because of the initial downward and outward slope of the shoulder 5 of cup 11B and the deformation of the bottom 3 of cup 11A both of these zones are inclined downwards and outwards and hence further axial loading results in the bottom 3 of the cup 11A tending to expand whilst the shoulder 5 of cup 11 B tends to contact and these forces interact to positively prevent overriding of the corner 10 over the corner 9 and as shown in Figure 2. Thus, the inclination of the shoulder 5 positively prevents the jamming of a stack of nested cups together.
A typical cup as shown in Figures 4, 5 and 6 may be of 7 fluid ounce (200 ml) capacity, may be made by thermoforming from a sheet of high impact polystyrene having an initial thickness of 0.8 mm. Each cup uses a disc 74.5 mm in diameter. The deformation of the heated sheet is started mechanically by a plug and is finished by the emission of air under pressure into the interior of the preform created by the plug. Preferably the corners in the mould which produce the corners 8, 9 and 10 in the cup all have radii in cross section not exceeding 0.25 mm. It is preferred that for most of the particular cup the measurements of the vertical centre line of the mould are as follows:

to the corner forming corner 8 of the cup 30.00 mm
to the corner forming corner 9 of the cup 29.00 mm
to the corner forming corner 10 of the cup 29.75 mm.

In the finished cup the thickness of the sheet around the shoulders 4, 5 and in the bottom 3 is preferably nowhere less than 0.15 mm.
The second example of cup in accordance with this invention is shown in Figure 7 and in this second example the continuous inclined annular shoulder 5 is interrupted to form a castellated shoulder. First, in this example a series of shoulders 5 (lands) inclined to a plane normal to the axis of the cup is intercollated with lands 4 which lie in a plane normal to the axis of the cup. A normal stack of such cups is shown in Figure 8 and the bottom 3 of cup 12A is normally supported on the corners 9 of the inside edge of the inclined lands 5. When the stack of cups is subjected to an axial load the bottom 3 of the cup 13A is subjected to local deformation as shown in Figure 9 in an analogous fashion to that of the first example and this deformation of the bottom 3 of the cup 12A absorbs the shock of any axial loading. After the bottom 3 of the cup 12A has been deformed the corner 10 moves down into contact with the corner 8 to provide a positive stop. This is the position shown in Figure 9. Again the deformed parts of the bottom 3 resting against the inclined lands 5 tend to cause the corner 10 to expand circumferentially and the corner 9 to contract circumferentially so tending to oppose overriding of the corner 10 over the corner 9.
Both examples of cups in accordance with this invention include a number of radially extending nibs 14 located immediately above the inclined annular shoulder 5. This feature will be described in detail with reference to Figure 10 which is the first example. The nibs 14 are arranged so that there is minimal or possibly zero clearance between the apeces of the nibs 14 of cup 13A and the side wall 2 of the cup 13B when cup 13A is nested inside cup 13B as shown in Figure 11. When the stack of such cups is subjected to an axial load the outer periphery of the bottom 3 distorts in a similar fashion to that already described. At this point the apeces of the nibs 14 on the cup 13A begin to dig in and deform the side wall 2 of the cup 13B. This digging in and deformation provides an additional force to absorb the shock of any axial load and decreases the restoring force to return the cups to their normal nested configuration. The nibs 14 also have the effect of centralising the cups together which again helps to prevent the corner 10 overriding the corner 9 as a result of any misalignment between adjacent cups of the stack.
A modification is shown in Figure 12 and in this modification the nib 14 has a steeply inclined base 15. The steeply inclined base 15 increases the sharpness of a corner 16 between the apex of the nib 14 and its base and helps to increase the digging in effect of the nib 14 into the side wall 2 of a cup below it in a stack, thus increasing its resistance to impaction still further.
For the sake of clarity, only two cups have been shown throughout this description to represent a stack of cups and any locking means to lock together the cups into a stack has been omitted. In practice, a stack of ingredient cups after being filled with ingredient powder 7 is usually encased in a sheath of plastics film and then a number of such stacks are packaged in a cardboard case before being transported.

Claims

1. A nestable cup or other container comprising a bottom (3), a side wall (2), and stacking means including a circumferential shoulder having an internal, upwardly facing surface (5) inclined in a direction downwards and outwards and terminating at an acute angled convex corner (9), the surface being either continuous or interrupted to form castellations so that, when a plurality of identical cups (11, 12, 13) or other containers are assembled together into an upright stack, the corner (9) of the cup (11B, 12B, 13B) or other container makes localised contact with the stacking surface of the cup (11A, 12A, 13A) or other container above, the corner (9) engaging the stacking surface away from its edge (10), characterised in that a plurality of circumferentially spaced externally projecting nibs (14) having bases inclined downwards and outwards are included around the stacking means and arranged so that when the cups (13A) or other containers are nested the nibs (14) on the upper cup (13A) or container are very close to, or touch, the interior of the side wall (2) of the next cup (13B) below.

2. A cup or other container according to claim 1, made from high impact polystyrene, other grades of polystyrene, polypropylene, or polyvinyl chloride.

3. A cup or other container according to claim 1 or 2, in which the inner upwardly-facing shoulder (5) is inclined at an angle within a range of 5° to 10° to a plane normal to the axis of the cup (13) or other container.

4. A cup or other container according to any one of the preceding claims, in which the thickness of the stacking means (4, 5) and the bottom (3) is nowhere less than substantially 0.15 mm.

5. A method of making a cup or other container according to any one of the preceding claims, in which a plastic sheet materials is pressure formed in a female mould having corners with radii in cross-section not exceeding 0.25 mm.

6. A method according to claim 5, in which the part of the mould which forms the upwardly-facing shoulder (5) is incined at an angle within a range of 5° to 10° to a plane normal to the axis of the cup (13) or other container.