GB2136775A

GB2136775A - Lidded containers

Info

Publication number: GB2136775A
Application number: GB08307987A
Authority: GB
Inventors: Donald Kenneth Budd; Douglas James Jaques
Original assignee: Metal Box PLC
Current assignee: Crown Packaging UK Ltd
Priority date: 1983-03-23
Filing date: 1983-03-23
Publication date: 1984-09-26
Also published as: FR2543111A1; GB2136775B; GB8307987D0; KE3788A; FR2543111B1; DE3410420A1; IN159711B; MY8800148A; ZA841688B; ZW4584A1

Abstract

A tubular body (6) of a container has protruding latching means (12), around the mouth, with which an inwardly directed curl (11) of the lid co-operates to retain the lid (5) on the body (6). The body (6) is round and the curl (11) is an elliptical hoop so that when a pinching force is applied along the major axis of the elliptical hoop the minor axis is spread to unlatch the lid from the body. The principle may be applied to other body shapes such as elliptical, oval and bow sided rectangular. <IMAGE>

Description

SPECIFICATION Containers This invention relates to containers having removable and replaceable lids and more particularly but not exclusively to metal containers having metal lids.

"Slip lid" metal containers are well known in which the tubular side wall of the body defines the mouth of the container and the metal slip lid comprises a cover panel spanning the mouth of the container and a skirt extending from the periphery of the cover panel to surround the side wall of the body so that the fictional forces, arising from this "telescoping" engagement, retain the lid or the tin. One such tinplate container was used for dried milk and in order to achieve a secure frictionally retained lid the skirt was made quite long. Such lids were difficult to removefortwo reasons; firstly the lid skirt had raw edge which was difficult to grip and secondly the frictional engagement was considerable in spite of control of the tolerance of lid fit.

Drawn tinplate containers for shoe polish are known in which the body sidewall has a mouth defined by an inward curl supported on a peripheral barrelled portion which terminates at an outwardly extending bead. The shallow slip lid has a cylindrical skirt which engages with the barrelled portion of the body in a tight hoop of contact. The hoop of contact has to be tight to prevent loss of solvents from the polish so it is usual for these polish tins to have some means to assist removal of the from the body.

In one known polish tin a double ended lever, called a wing opener, is rotated to apply pressure a curl on the lid skirt to lever open the tin. Provision of such levers is costly in time and materials.

In another known polish tin the raw edge of the slip lid has a cam surface so that a pinching action applied to the top edge of the lid and bottom of the body causes the lid to swing open. The manufacture of lids with a cam surface is not always convenient, the tolerance of the lid to body fit requires careful control, and the raw edge at the cam surface is not entirely safe.

Round tinplate containers for tobacco are known in which the shallow slip lid comprises a closure panel provided with a peripheral channel in which is located a gasket of lining compound. The peripheral skirt of such lids is curled to give a safe edge and includes inwardly directed beads to snap fit under a co-operating bead in the sidewall of the container body. The primary seal of such container is achieved by vacuum packing so that reduced pressure within the container pulls the lining compound into sealing engagement with a curl at the top of the sidewall defining the mount of the container.The reclosure is achieved by snap fitting the co-operating beads and if this reclosure is to be secure the fit must be controlled to tight tolerances and may still be somewhat difficult to overcome because the shallow lid has very little to grip and very little elasticity to facilitate the snap fit action.

The problems may be summarised as being that, long skirted slip lids are difficult to open because of the extended zone of frictional engagement which costs extra metal; and short skirted slip lids require retention features which require close control of tolerances during manufacture and may require additional manufacturing operations such as provision of levers.

This invention provides a container having a tubular body closed at one end by a slip lid having a closure panel and a skirt extending from the periphery of the closure panel to surround the tubular body, the lid and body being held together by co-operation of latching means of the body sidewall and skirt, characterised in that diametrically opposed pinching forces applied to the skirt or body disengage the co-operating latching means to permit removal of the lid from the body.

The latching means of the tubular body may be in the form of an outwardly directed curl defining the mouth of the container, or a groove in the sidewall adjacent the mouth, in which case the lid skirt would be provided with an inwardly directed curl to engage the under side of the curl or enter the groove, the lid curl being of a hoop length greater than the maximum hoop length of the tubular body but of a shape such that a first pair of opposed latching portions engage the body latching means and further pair of opposed unlatching portion extend outboard of the tubular body so that application of opposed pinching forces to the unlatching portions deforms the lid curl to disengage the latching portions from the body.

In a preferred embodiment the latching means of the body is an outwardly directed annular bead which may be continuous or interupted.

Various embodiments will now be described by way of example and with reference to the accompanying drawings in which: Figures laand 1b show diagrammatically the principle of lid retention; Figure 2 is a perspective view of a first embodiment of the principle; Figure 3 is an underplan view of a second embodiment; Figure 4 is a side elevation sectioned on line A-A' in Figure 3; Figure 5 is a side elevation sectioned on line B-B' in Figure 3; Figure 6 is a sectional perspective view of a third part shown in section; Figure 7 is a side view of a fourth embodiment sectioned on a diameter; and Figure 8 is a perspective view of a fifth embodi mentwhen closed; Figure 9 is a perspective view of the fifth embodiment when open; and Figure 10 is a perspective view of a sixth embodiment in which the lid is shown part cut away.

In Figure 1 a an ellipse 1 represents an array of latching means of one container member adapted to co-operate with latching means of another container member depicted as a circle 2. Arcuate zones of interference 3 make it possible for the ellipse 1 to be lifted past the circle 2.

In Figure 1 b diametrically opposed pinching forces F have been applied along the major axis of the ellipse 1 to change the shape to a circle 1' of girth large enough to permit lifting of the originally elliptical shape past the circle so that the container members may be separated.

In Figure 2 a tall container comprises a body 4 closed at the top end by a slip lid 5. The body has a tubular sidewall 6 having a side seam (not shown) and bottom attached to the tubular sidewall 6 by means of a double seam 7. The top end of the sidewall 6 is in the form of an inwardly directed curl 8 which defines the mouth of the container.

The lid 5 comprises a closure panel 9, an annular channel portion 10 surrounding the closure panel, and a skirt 13 depending from the periphery of the channel portion. The skirt 13 has a cylindrical portion 14 which is a slack fit on the body and extends from the channel portion 10 to an outwardly flaring annular portion 15 which terminates in an inwardly directed curl 11.

The curl 11 is an elliptical hoop adapted to engage with a circular array of protrusions 12 on the tubular sidewall. Application of diametrically opposed pinching forces, as indicated by arrows on the lid, along the major axis of the ellipse, at which there is a gap between the curl 11 and protrusion 12', deforms the hoop shape of curl 11 to a substantially circular shape of girth sufficiently large to permitthe lid 5 to be lifted past all the body protrusions 12.

Various modifications of this first embodiment are possible, for example a gasket of lining compound may be incorporated into the channel portion 10 and the protrusion 12 may be replaced by a continuous bead in the form of a circular hoop. The skirt shape may also be simplified as is described by reference to a second embodiment.

In Figures 2,3 and 4 a second embodiment of the container comprises a body drawn from a sheet metal such as a temper 2 or 3,tinplate. 2mm thick having an E2.8 tin coating on both sides. The body has a bottom wall 17 integral with a sidewall 18. The sidewall extends from the periphery of the bottom wall and comprises a lower cylindrical portion 19 and outwardly extending circular bead 20, an upper cylindrical portion 21 and an inwardly directed curl 22. By virtue of the shape and materials chosen the body is substantially rigid.

The lid comprises a closure panel 23, a channel portion 24 surrounding the closure panel and containing a gasket 25 of lining compound, and a skirt 26 depending from the channel portion 24to terminate in an inwardly directed curl 27. The curl 27 comprises a pair of substantially arcuate latching portions 28 which embrace the underside of the body bead 20, as is best seen in Figure 4, and a pair of substantially arcuate unlatching portions 29 held outboard of the body bead, as shown in Figure 5, at a clearance greater than the radial extent of the curl, by joining portions 30. A useful clearance tolerance is the thickness of bead plus .010" (2mm), however greater clearance will suffice. Each unlatching portion subtends, at the centre of the lid, an angle of about 70".

It is important that the lid be flexible and this may be achieved by use of a thinner material than the body. For example 0.17mm thick DR 8 tinplate with an E2.8 tin coating on both sides. Although flexibility may be achieved by choice of temper of sheet material used, the DR tinplates, (as defined in British Standard Bs 2920: 1973 and Euronorm 145.78; 150 R1 111 have desirable springlike qualities. Soft materials may fail to spring back for reclosure.

In one form the lid is 4" diameter (100 mm) and the skirt is 5/16" (14 mm) long, these dimensions permitting squeezing between fingers and thumb to open the container.

In Figure 6 a container comprises a drawn body 31 having a mouth defined by an external curl 32, and a slip lid 33 having a shallow skirt 34 terminating in an inwardly directed curl 35 of elliptical shape. It will be noticed that the skirt height is very small, demonstrating the influence of skirt length on the leverage available when pinching forces are applied in the direction of the arrows.

This problem may be overcome by providing a sidewall 36 having an inwardly directed bead 37 which defines an external groove and a lid with longer skirt length as shown in Figure 6.

The slip lid 23 depicted in Figure 7 works in the same way as the slip lid shown in Figures3, 4 and 5.

Alternatively the external curl of Figure 7 may be replaced by an elongated curl which has an external surface extending alongside the tubular sidewall until sufficient curl height is provided to permit the use of an adequately long skirt length on the lid for easy opening. However, an elongated curl would require extra metal.

Whilst the invention has been described in terms of round containers it is not limited thereto. The principle may, for example, be applied to containers of elliptical, oval or bow sided rectangular shapes, because, in each case compression in one direction can cause change in shape of the lid to unlatch latching means laterally disposed with respect to the direction in which compression is applied.

In Figures 8 and 9 an oblong box comprises a body 38 and a lid 39 hingedly connected to the body 38.

The body has a bottom 40 and upstanding from the periphery of the bottom, a pair of opposed straight side walls 41, a straight rear wall 42 and a bowed front wall 43. Near the top of the front wall 43 an elongate latching bead 44 protrudes from the wall.

The walls terminate in a continuous inwardly directed curl 45.

The lid comprises a top panel 46, a pair of opposed straight sides 47, a back 48 having hinge members 49 engaged with the rear wall 42 of the body, and a bowed front 50. The sides 47, back 48, and front all terminate in a continuous inwardly directed curl 51.

The inwardly directed curl 51 of the lid is spaced apart at a clearance from the straight side walls 41 of the body when the inward curl 51, of the front of the lid, is in snap fitted engagement under the latching bead 44 of the body. A suitable side curl to body side wall clearance would be at least equal to the thickness of the lid curl 51.

A pinching force applied into the sides 47 of the lid forces the curl 51 into the clearance space and bows the front of the lid to unlatch the lid curl 51 from the elongate latching bead 44 to permit opening of the lid.

In Figure 10 an oblong container comprises a rectangular body drawn from sheet metal to have a first pair of opposed bowed sides 52 connected by a second pair of bowed sides 53 longer than the first pair. The sides of the body terminate in an inwardly directed curl 54. Each of the longer sides is provided with an elongate latching bead 55 protruding from the side wall 53.

The lid comprises a flat central panel 56 surrounded by a channel portion 57 from which depends a skirt comprising a pair of shorter sides 58 and a pair of longer sides 59. The sides 58,59 terminate in an inwardly directed curl 60 which, at the longer sides engage with the underside of the latching bead 55. When the lid is closed the curl 60A at the shorter sides is held apart from the first opposed sides 52 of the body by a clearance of at least the curl thickness so that when a pinching pressure is applied to the shorter sides 58 of the lid the longer sides bow outwardly to unlatch the curl 60 from the latching bead 54.

The channel portion 57 may be provided with a gasket, such as a lining compound, to effect an airtight seal with the curl 54 of the body in which case the container will be suitable for vacuum packing to protect products such as tobacco and confectionery.

It will be understood by those skilled in the art that the various skirt shapes and latching features, described with reference to each embodiment, may be replaced by equivalent working features of the other embodiments.

It is apparent from the geometry of Figures 1 a and 1 b that both deformation of the ellipse 1 to circle or deformation of the circle 2 to an ellipse will unlatch the container from the lid. Whilst, in the packaging industry it is most convenient to make the container body rigid and the lid flexible, it may be useful in other applications to use a rigid lid and a flexible body. For example the body may be cover or guard for a component which requires mechanical protection.

Claims

1. A container having a tubular body closed at one end by a slip lid having a closure panel and a skirt extending from the closure panel to surround the tubular body, the lid and body being held together by co-operation of latching means of the body and skirt, characterised in that diametrically opposed pinching forces applied to the skirt or body disengage the co-operating latching means to permit removal of the lid from the body.

2. A container according to claim 1 characterised is that the lid is made of sheet metal and the skirt is flexible under the influence of the diametrically opposed forces.

3. A container according to claim 1 or claim 2 characterised in that while the diametrically opposed forces are applied to the skirt of the lid, the girth of the latching means of the lid exceed the girth of the co-operating latching means of the body.

4. A container according to any preceding claim characterised in that the skirt of the lid terminates in an inwardly directed curl which co-operates with latching means of the body.

5. A container according to claim 4 characterised in that the co-operating latching means of the body in an outwardly extending bead or interupted bead.

6. A container according to claim 4 characterised in that the co-operating latching means of the body is an annular groove into which opposed portions of the curl of the lid may enter.

7. A container according to claim 4 characterised in that the inwardly directed curl of the lid is a latching means in the form of an elliptical hoop adapted to co-operate with an outwardly directed annular bead of the tubular sidewall, said elliptical hoop being of minor axis less than the maximum diameter of the body bead and major axis greater than the body bead by a distance greater than twice the radial height of the body bead.

8. A container according to claim 4 characterised in that the inwardly directed curl of the lid has latching means in the form of a pair of opposed arcuate latching portions which, when closed, embrace the underside of an outwardly directed bead of the body, and a pair of opposite arcuate unlatching portions held outboard of the body bead by joining portions.

9. A container according to claim 8 characterised in that when the lid is closed the joining portions hold each unlatching portion outboard of the body bead at a minimum radial distance equal to the height of the bead measured radially of the body plus .010 inches (.0004 mm).

10. A container, substantially as hereinbefore described with reference to Figure 2, or Figures 3,4 and 5, or Figure 6, or Figure 7 or Figures 8 and 9 or Figure 10 of the accompanying drawings.