GB2296913A

GB2296913A - Integral hinge assembly connecting container base and lid

Info

Publication number: GB2296913A
Application number: GB9500717A
Authority: GB
Inventors: Ronald Frank Lovatt
Original assignee: DOLPHIN PACKAGING MATERIALS
Current assignee: DOLPHIN PACKAGING MATERIALS
Priority date: 1995-01-14
Filing date: 1995-01-14
Publication date: 1996-07-17
Anticipated expiration: 2015-01-14
Also published as: GB2296913B; GB9500717D0

Abstract

A one piece container, e.g. a salad container, comprises a base 2 and a lid 3 integrally connected together by a hinge assembly 4 which consists of an elongate flexible folding formation 8 defining a hinge axis 11 and hinge leaves 9 and 10 connecting the base and the lid to the folding formation, the leaves carrying formations which cooperate to obtain correct registration of the base and lid prior to full closure. The formations may consist of two pairs of transverse walls 12, 13 extending in planes perpendicular to the hinge axis and/or snap fitting triangular formations 18, 19. The container is preferably vacuum formed from transparent plastics material to provide a bowl shaped base which has corrugations 5 to provide rigidity.

Description

CONTAINERS FORMED FROM PLASTICS This invention relates to containers formed from plastics material, and particularly but not exclusively to containers produced by thermo-forming.

The invention relates in particular to containers comprising first and second shells which are integrally connected by a hinge assembly which is also formed from said sheet material.

Usually one of the shells will be of greater concavity than the other shell to provide a bowl or tray, to receive a food product for example, and the other shell of less concavity will act as a lid, but it should be understood that the shell of lesser concavity may act as a support for an item, such as a piece of gateaux, the shell of the greater concavity then providing a domed lid for fitting over the item.

It should be appreciated that the invention may also be applied to such containers in which the shells are of substantially equal concavity.

The shells will often be of transparent plastics material, such as PVC, Polystyrene, Polypropylene and P.E.T.

The invention stems from a requirement to provide a vacuum-formed container comprising a hinged lid on a bowl, the lid being capable of being automatically brought to a closed position on a food filling line, by urging the lid to swing relative to the bowl, and so as to ensure that the lid is closed in register with the rim of the bowl. Existing hinge assemblies incorporated in vacuum-formed containers are generally too 'floppy' to provide consistent registration between the lid and the bowl on a production line.

Such hinge assemblies are often of corrugated nature, comprising a plurality of undulations extending parallel to the desired hinge axis.

We have devised a hinge assembly which can be arranged to ensure that the lid is brought to a position in register with the bowl when the lid is closed onto the bowl.

According to one aspect of the invention a container formed from plastics material comprises first and second shells integrally connected together by a hinge assembly also formed from said plastics material, the hinge assembly comprising: (a) an elongate flexible folding formation adapted to define a hinge axis for relative hinging of the first and second shells from an open position in which the container is formed, to a closed position; (b) first and second hinge leaves connecting the first and second shells respectively to the folding formation; and (c) cooperating formations formed in the first and second hinge leaves which are adapted to cooperate with one another as the hinge leaves are moved from an open position towards a closed position, the formations being so shaped as to assist in preventing twisting of the hinge leaves relative to planes which include the hinge axis, thereby to assist in obtaining registration of the first and second shells prior to full closure thereof.

Preferably said cooperating formations on the hinge leaves comprise at least two pairs of transverse walls, that is walls extending substantially in planes perpendicular to the hinge axis, one transverse wall of each pair being provided on one of said hinge leaves, and the other transverse wall of each pair being provided on the other of said hinge leaves, the arrangement being such that the transverse walls of each pair cooperate with one another to restrict relative axial movement of the hinge leaves in both axial directions.

The pairs of transverse walls are preferably provided by complementary channel-section ribs formed in the hinge leaves, a rib on one hinge leaf being received substantially within the cavity of the rib on the other hinge leaf.

Preferably each hinge leaf is formed with two such ribs which are preferably located adjacent to opposite axial ends of the folding formation.

The cooperating formations on the hinge leaves preferably comprise at least one pair of cooperating parallel walls, that is walls extending substantially in planes parallel to the hinge axis but spaced therefrom, and provided on the respective hinge leaves.

Said parallel walls are preferably arranged to provide a snapengagement between the hinge leaves on closure thereof, this being achieved by locating the parallel walls relatively close to the hinge axis. It will be appreciated that because said parallel walls do not extend circumferentially about the hinge axis, rather substantially tangential to the notional circumferential direction of relative movement of the hinge leaves, a snap-action can be achieved by positioning the parallel walls such that they lie in face contact with one another in the closed condition of the hinge leaves.

The cooperating formations preferably comprise formations having a substantially L-shaped margin as viewed normal to the plane of the hinge leaves, one limb of the L providing one of said parallel walls, and the other limb of the L providing one of said transverse walls.

In order to assist in rigidifying the hinge leaves, each hinge leaf is preferably of joggled cross-section in planes transverse to the hinge axis for most of the axial length of the hinge leaves.

In one preferred embodiment the step of the joggle is continuous at its opposite ends, by way of a respective rounded corner, with steps defining said transverse walls, thereby providing a raised elongate platform on one leaf which cooperates with a complementary depression in the other leaf. The raised platform is formed with substantially triangular depressions adjacent to opposite ends thereof, and said complementary depression is formed with complementary triangular projections for fitting with said triangular depressions on closure of the hinge leaves. The L-shaped sides of the triangular depression act in the manner previously described.

In order to define a substantially predetermined hinge axis, said elongate flexible folding formation is preferably of substantially U-shape in transverse cross-section, in the fully-open, as-formed condition of the hinge, but opposite ends of the folding formation have a U-shape of progressively smaller dimensions, so as to rigidify the opposite ends of the folding formation.

A salad container in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a plan view of the container in the as-formed, fullyopen condition; Figure 2 is a side elevation of the fully-open container; Figure 3 is a section on the line 3-3 of Figure 1; Figure 4 is a side elevation of the fully-closed container; Figure 5 is a sectional isometric view of the fully-open container; Figure 6 is three enlarged views of the fully-open, as-formed hinge formation, (a) an isometric view, (b) a wire-frame isometric view, tc) a wire-frame half section; Figure 7 is a longitudinal cross-sectional view of the hinge formation, taken on the line 7-7 of Figure 6; Figure 8 is an end view of the fully-open hinge formation looking in the direction of the arrow B in Figure 6(b);; Figure 9 is a local section on the line A-A of Figure 1 showing the hinge leaves in a fully-open condition of the container; Figure 10 is a local section on the line A-A of Figure 1 but showing the hinge leaves in a partially-closed condition of the container; and Figure 11 is a section similar to Figure 10.

With reference to Figures 1 to 3, a salad container 1 has been vacuum formed from transparent sheet plastics material, and comprises a first shell in the form of a bowl 2 and a second shell in the form of a lid 3 integrally connected by a hinge assembly 4 also produced from the sheet material during the vacuum forming process which produced the bowl 2 and lid 3.

The bowl 2 and lid 3 are of a conventional shape, the bowl being provided with bands of corrugations 5 to improve the rigidity of the bowl, and the bowl, as shown in Figures 1 and 3, is formed with a peripheral annular channel section 6 which mates with a complementary annular, cross-section formation 7 provided on the lid.

The invention is concerned with ensuring that the annular formations 6 and 7 are brought together in register when the lid 3 is pivoted from the open position of Figure 2 to the closed condition of Figure 4.

The hinge assembly 4 comprises an elongate hinge formation 8, shown enlarged in Figure 6, connected respectively to bowl 2 and lid 3 by respective hinge leaves 9 and 10 which are of substantially joggled cross-section (shown best in Figure 5) for most of their axial length, in the plane perpendicular to the hinge axis 11, which is defined by the axis of the hinge formation 8, as shown in Figure 6(b). The joggles are defined by parallel walls 12, 13, that is walls extending parallel to the hinge axis 11, and generally perpendicular to the plane of the paper in Figure 1.

The parallel walls 12, 13 at their opposite ends are continuous, by way of rounded corners 14 with respective transverse walls 15, that is walls that extend transversely of the hinge axis 11 and substantially normal to plane of the paper in Figure 1. Walls 12, 13 and 15 are of substantially equal height in the direction normal to the plane of the paper in Figure 1, so as to define a complementary elongate platform 16 and recess 17 which closely fit one inside the other when the lid is filly closed onto the bowl.

Complementary triangular-shaped, as viewed in Figure 1, projections and recesses 19 and 18 have a snap-engagement with one another on closure of the hinge leaves, the initial snap of this engagement being arranged to take place at an intermediate stage of closure, as shown in Figure 10, such that the hinge leaves are held against twisting relative to each other, thereby to ensure that the lid 3 is in register with the bowl during the final stages of closing.

The triangular projections and recesses 19, 18, as shown in Figure 1 are each defined by a generally L-shaped profile and a hypothenuse, the L-shaped profile being formed by a respective parallel wall 20, that is a wall extending parallel to the hinge axis 11 and normal to the plane of the paper in Figure 1, and by a respective transverse wall 21, that is by a wall extending transverse to the hinge axis 11 and normal to the plane of the paper in Figure 1.

The snap-engagement of projections 19 with recesses 18 arises from the fact that the pairs of faces 20 fit snugly against one another in the closed condition of Figure 11, and are closely spaced from the hinge axis. The relative rigidity of hinge formation 8 means that the faces 20 do not align precisely with one another on initial closing of the hinge leaves, but then snap into place.

The co-operation between the various pairs of transverse faces 15 and 21 on the hinge leaves 9, 10 during initial closure of the hinge leaves helps to prevent any relative axial movement of the hinge leaves, and thereby help to hold the lid 3 against twisting relative to the bowl 2.

It will be noted that at each end of the platform 16, and complementary recess 17, the adjacent pairs of transverse faces 15 and 21 in effect define channel section ribs 22, Figure 1, which extend transversely of the hinge axis and fit one within another when the hinge leaves 9, 10 snap together at an intermediate stage of closure of the lid 3.

It will be realised that once the hinge leaves 9, 10 have snapped together, the portion 23, Figure 1, of the annular rib 6, that is that position of the rib 6 connecting with hinge leaf 9 will begin to cooperate with the adjacent portion 24 of the annular recess 7 on the lid 3, and this cooperation will assist in maintaining registration between the lid and the bowl as the lid is closed down onto the bowl.

On a production filling line the closure of the lid onto the bowl can be brought about by a suitable part-helical guide bar which engages with the lid as the container is conveyed along the line with the bowl supported on a conveyor.

With reference to Figures 6 and 7, the hinge formation comprises a vacuum-formed U-section which is reduced in transverse dimensions adjacent to the opposite ends thereof. In trimming of the vacuum-formed sheet, to define marginal flanges 25 on the bowl 2, lid 3 and hinge assembly, it is important to trim the hinge assembly as shown in Figure 6(a) so as to cut-off the point of the vacuum-formed recess of Figure 7.

Claims

1. A container formed from plastics material, comprising first and second shells integrally connected together by a hinge assembly also formed from said plastics material, the hinge assembly comprising: (a) an elongate flexible folding formation adapted to define a hinge axis for relative hinging of the first and second shells from an open position in which the container is formed, to a closed position; (b) first and second hinge leaves connecting the first and second shells respectively to the holding formation; and (c) co-operating formations formed in the first and second hinge leaves which are adapted to co-operate with one another as the hinge leaves are moved from an open position towards a closed position, the formations being so shaped as to assist in preventing twisting of the hinge leaves relative to planes which include the hinge axis, thereby to assist in obtaining registration of the first and second shells prior to full closure thereof.

2. A container as claimed in claim 1, wherein said co-operating formations on the hinge leaves comprise at least two pairs of transverse walls, that is walls extending substantially in planes perpendicular to the hinge axis, one transverse wall of each pair being provided on one of said hinge leaves, and the other transverse wall of each pair being provided on the other of said hinge leaves, the arrangement being such that the transverse walls of each pair co-operate with one another to restrict relative axial movement of the hinge leaves in both axial directions.

3. A container as claimed in claim 2, wherein the pairs of transverse walls are provided by complementary channel-section ribs formed in the hinge leaves, a rib on one hinge leaf being received substantially within the cavity of the rib on the other hinge leaf.

4. A container as claimed in claim 3, wherein each hinge leaf is formed with two such ribs located adjacent to opposite axial end 5 of the folding formation.

5. A container as claimed in any one of claims 1 to 4, wherein the cooperating formations on the hinge leaves comprise at least one pair of cooperating parallel walls, that is walls extending substantially in planes parallel to the hinge axis but spaced therefrom, and provided on the respective hinge leaves.

6. A container as claimed in claim 5, wherein said parallel walls are arranged to provide a snap-engagement between the hinge leaves on closure thereof.

7. A container as claimed in claim 6, wherein said snap-engagement is achieved by positioning the parallel walls such that they lie in face contact with one another in the closed condition of the hinge leaves.

8. A container as claimed in any one of claims 1 to 7, wherein the cooperating formations comprise projections for location by complementary depressions on closure of the hinge leaves.

9. A container as claimed in claim 8, wherein the co-operating formations comprise formations having a substantially L-shaped margin as viewed normal to the plane of the hinge leaves, one limb of the L providing one of said parallel walls, and the other limb of the L providing one of said transverse walls.

10. A container as claimed in any one of claims 1 to 9, wherein each hinge leaf is of joggled cross-section in planes transverse to the hinge axis for most of the axial length of the hinge leaves.

11. A container as claimed in claim 10, wherein the step of the joggle is continuous at its opposite ends, by way of a respective rounded corner, with steps defining said transverse walls, thereby providing a raised elongate platform on one leaf which co-operates with a complementary depression in the other leaf.

12. A container as claimed in claim 11, wherein the raised elongate platform is formed with substantially triangular depressions adjacent to opposite ends thereof, and said complementary depression is formed with complementary triangular projections for fitting with said triangular depressions on closure of the hinge leaves.

13. A container as claimed in any one of claims 1 to 12, wherein said elongate flexible folding formation is preferably of substantially U-shape in transverse cross-section, in the fully-open, as-formed condition of the hinge, but opposite ends of the folding formation have a U-shape of progressively smaller dimensions, so as to rigidify the opposite ends of the folding formation.

14. A container as claimed in any one of claims 1 to 13, formed from transparent plastics material.

15. A vacuum-formed container as claimed in any one of claims 1 to 14.

16. A container as claimed in any one of claims 1 to 15, wherein one shell is formed with a peripheral, annular, channel section which mates with a complementary annular projection formed on the other shell.

17. A container as claimed in any one of claims 1 to 16, wherein one shell comprises a bowl and the other shell comprises a lid for the bowl.

18. A container as claimed in claim 17, wherein the bowl is provided with corrugations to improve rigidity of the bowl.

19. A container as claimed in claim 17 or 18, wherein the bottom of the bowl defines an outwardly-presented concavity.

20. A container substantially as hereinbefore described with reference to the accompanying drawings.