CA2633092A1 - Container with lid for packaging pourable materials - Google Patents

Abstract

The invention relates to a container with a container body made of a material such as metal, PE or cardboard, which has a primary opening, which is closed by a smooth metal plate acting as a first lid element, the smooth metal plate comprising a lid tab which is defined by a parting line and, after being broken open, exposes an outlet opening, and the lid tongue having a sloping surface, which interacts with a first projection arranged on an opening means that is movable substantially parallel to the smooth plate for applying a force to the lid tab to break open the parting line.
In order to ensure that adequate force for breaking open the smooth plate at the parting line of the lid tab can be provided in the case of such a generic container, it is proposed to provide a depressed bead (32) and, alongside it, an elevated bead (36) on the lid tab (30), the sloping surface being made up at least of one portion of a flank (33) of the depressed bead and at least one portion of a flank (37) of the elevated bead. The invention also relates to a lid (20, 50) for such a container and to a method for opening such a container.

Description

Container with lid for packaging pourable materials The invention concerns a container comprising a container body having a primary opening which is closed by a metal plate portion acting as a first lid element, wherein the metal plate portion includes a lid tab which is defined by a separation line and which after being broken open opens a discharge opening, and the lid tab has an inclined surface co-operating with a first projection arranged on an opening means movable substantially parallel to the plate portion for applying a force to the lid tab in order to break open the separation line. The invention further concerns a lid for a container of that kind and a method of opening such a container.
Such a container of the general kind set forth is disclosed for exampie in US patents Nos 3 726 432 and 5 816 427 and in EP 1 265 792 B1. In that case the lid of the container is of such a configuration that a projection of a lid element is moved in the plane of the plate portion and can be guided on an inclined surface on the lid tab so that a force extending substantially in a normal direction relative to the lid tab can be produced, whereby the metal plate portion breaks open along a separation line so that the discharge opening is opened. With such a container of the general kind set forth therefore it is possible to dispense with the breaking-open ring which nowadays is frequently used at least in relation to disposable drinks cans and which in the opening operation is pivoted out of the plane of the plate portion and acts by way of a lever on the lid tab to break open the separation line. With such a container of the general kind set forth however care has to be taken to ensure that the force applied by the co-operation of the projection with the inclined surface is sufficient, even when flexing of the plate portion occurs, to break open the plate portion at the separation line. Such flexing of the plate portion can scarcely be avoided, particularly in the case of the disposable drinks cans which are used nowadays, as the wall thicknesses of the container are very small.
Usually, such an inclined surface is provided in the lid plate portion by means of the flank of a bead which is shaped in the metal plate portion. In order to ensure that the plate portion breaks open at the separation line in the opening process and the lid tab is bent out of the plane of the plate portion, the travel distance, governed by the system involved, must be greater than the flexing of the plate portion. In that respect it is advantageous if that travel distance, governed by the system concerned, that is to say the bead height or depth, is as great as possible. However, limits are imposed on just prolonging the bead flank serving as the ramp, as much as may be desired, as the small thickness of the plate portion means that severe deformation of the material of the plate portion occurs as from a given bead height or depth. It is precisely in the region of the separation line however that there is only limited material for shaping the inclined surface as the region of the lid tab is precisely surrounded by the separation line.
The object of the invention is to ensure that, in a container of the general kind set forth, it is possible to provide a sufficiently high force for breaking open the plate portion at the separation line of the lid tab.
That object is already attained by the present invention in a surprisingly simple fashion by a container having the features of claim 1, an associated container lid having the features of claim 20, and a method of opening such a container having the features of claim 21.
In that respect a container according to the invention has a lid tab which includes both a depressed bead and also adjacent thereto a raised bead, wherein the inclined surface is composed at least of a portion of a flank of the depressed bead and at least a portion of a flank of the raised bead.
The fact that the inclined surface, that is to say the ramp along which the projection is guided in the opening operation is composed of the flanks of two beads directed in different directions means that ultimately it is possible to provide a greater ramp length and thus ramp height. In that respect the term ramp height is used to denote the extent of the inclined surface parallel to the axis of the container. The adjacent formation of a depressed bead and a raised bead means that it is possible to precisely compensate for deformation forces and stress which can cause folding of the material so that, with the combination of two oppositely formed beads, it is possible to provide a greater effective ramp height in comparison with the configuration of a raised bead or a depressed bead on the lid tab for providing an inclined surface, acting as a control surface, for the projection.
Such a configuration of the container according to the invention is particularly suitable in those cases in which it is not possible to carry out a deep-drawing process with holding-down means (folding holder) in the shaping procedure on the lid, but it is only possible to effect shaping of the lid plate portion with a positive or negative shaping means.
The separation line on the first lid element for defining the lid tab can be for example in the form of a weakening line such as a tear line, but it is also possible for the plate portion to be cut through along the separation line and for the cut subsequently to be closed again for example by applying a plastic material to the inside of the lid in the region of the separation line. In the art a discharge opening prepared in that way is referred to as a 'post-repair' opening. In that case, in the opening process, that plastic material layer and therewith the separation line are ruptured by application of the force to the lid tab and subsequently the lid tab is bent inwardly into the container.
The container according to the invention can include a container body of a material which in particular is stable in respect of shape such as metal, plastic material such as polyethylene, cardboard or also a composite material. The plate portion acting as the first lid element for closing the container body is generally made from metal to permit the usual shaping processes to be performed to produce the lid configuration.
The term 'bead' is used to generally denote a depression or raised configuration in the plate portion of the lid, the bead height or depth generally being related to the main plane of the plate portion.
A large number of different design configurations are also possible in accordance with the invention for the opening means which is movable substantially parallel to the plate portion and on which the first projection is disposed. By way of example that opening means can be in the form of a linear slider or a rotary slider, wherein the projection performs a linear or a rotary movement, on the control surface.
Advantageous embodiments of the invention are recited in the appendant claims.
In order to provide for the best possible compensation of the stresses in the material in the region of the lid tab during production of the inclined surface, it can be provided that the depressed bead and the raised bead go into each other without a step, wherein the transitional region is formed substantially without a bead bottom. In that respect the flank of the raised bead directly adjoins the flank of the depressed bead, in which respect it may be desirable if both flanks in the transitional region involve the same gradient in relation to the surface of the plate portion.
The bead width, the bead flank and the bead height of the depressed bead and the raised bead respectively can be matched to the respective requirements involved. An oval shape in plan view can be advantageous for example if a projection co-operating with the bead or a flank of the bead is of a predetermined configuration so that the bead is adapted to that configuration or to the curve which the projection describes during the opening movement.
It may be desirable if the bead depth of the depressed bead is substantially equal in magnitude to the bead height of the raised bead. In that case the stresses in the material of the plate portion, which occur by virtue of shaping the beads in the lid tab, can be particularly symmetrically compensated. The stress compensation effect afforded by the adjacent arrangement of the raised and depressed beads also permits in particular a simplified method of manufacturing the container of the invention in the region of the lid as by means thereof it is possible for the depressed bead and the raised bead to be respectively produced in the lid tab in one shaping operation without the use of a hold-down arrangement.
The transmission of force to the lid tab can be adjusted very accurately and in dependence on for example the material of the plate portion of the lid and the thickness thereof, by setting predetermined flank angles for the beads. It has proven to be advantageous for a conventional plate portion if the depressed bead and/or the raised bead in the operative region of the inclined surface with the associated first projection has or have a flank angle of 300 to 70 , in particular 40 to 50 . The fiank angle denotes the angle of the flank of the bead relative to the main plane of the 5 lid tab or the surface of the plate portion.
In order to prevent an increased internal pressure in the container increasing the force required to break open the separation line defining the lid tab and thus the necessary ramp height, it may be desirable to provide a venting means connected in respect of motion to the opening means for venting of the container prior to the separation line defining the lid tab being broken open. That ensures that the container is vented before the actual operation of breaking open the separation line and opening the discharge opening. That is desirable in particular in relation to those containers which contain a carbonated drink. As the opening means and the venting means are moved simultaneously and with each other, it is possible with a single movement of one element firstly to vent the container and subsequently then to open the discharge opening by breaking open the separation line defining the lid tab.
It is particularly desirable if the lid tab includes a vent tab which is defined by a separation line extending on the lid tab, wherein the venting means includes a second projection which in the movement of the opening means co-operates with the vent tab to produce a force approximately perpendicular to the plate portion on the vent tab in order to break open the separation line of the vent tab. That design configuration aspect has on the one hand the advantage that, in spite of the provision of a venting means, the plate portion does not have to be designed to provide a further opening as that vent opening is disposed precisely on the lid tab which defines the actual discharge opening. Such a design configuration is particularly advantageous if the container is designed to be re-closable.
To ensure that the vent tab opens the vent opening before the separation line of the lid tab is broken open, it can be provided that the first projection which is arranged at the opening means and which is associated with the inclined surface on the lid tab in its starting position before the separation line of the lid tab is broken open projects into the depressed bead and has therein a free travel, within which the first projection does not contact the inclined surface in the movement of the opening means in the opening direction. In that respect it may be advantageous if the second projection which is arranged on the venting means and which co-operates with the vent tab in its starting position before the separation line of the lid tab is broken open is arranged in the immediate proximity of the vent tab.
That structural feature provides that the second projection, during the opening movement, co-operates directly with the vent tab for opening the vent opening before the first projection co-operates with the inciined surface formed by the depressed and raised beads to open the discharge opening. In that respect the second projection advantageously has a free travel during the opening movement, which is less than that of the first projection.
It may be desirable if the vent tab has a raised bead which in plan view is for example of a circular configuration.
Various measures can be envisaged for connecting the plate portion which includes the lid tab to the container body. For example the plate portion can be connected to the container body by a fold configuration, adhesive means or soldering means.
A particularly compact structure in the region of the lid can be achieved if the opening means which is movable substantially in the plane of the plate portion for applying a force to the lid tab is in the form of a second lid element which is arranged over the first lid element and is mounted rotatably relative thereto, wherein the second lid element has an eccentric opening which can be brought over the discharge opening by rotation of the second lid element. In that respect it may be desirable if the second lid element is of substantially the same radial extent relative to the axis as the first lid element and is rotatable relative to the container body about the axis thereof. In that respect the second lid element can have a peripheral annular groove which receives the container edge and/or an edge of the first lid element, which is in the form of an annular flange or an annular bead, wherein the second lid element is mounted rotatably relative to the container body and the first lid element. The second lid element can include a material of the container body and/or a material of the first lid element.
To permit re-closure of the opened container, it can be provided that disposed between the first and second lid elements outside the separation line of the lid tab is a sealing means, in particular in the form of a bead of a sealing material which extends in peripheral relationship at the edge of the discharge opening. On the other hand it can also be provided that seals having a sealing action together are arranged not only at one of the lid elements but at both lid elements.
To prevent the first projection being moved through the seal and thus damaging it after the separation line of the lid tab has been broken open, upon continuing rotation of the opening means, it can be provided that the first projection at the opening means comes to bear against the edge of the discharge opening, thereby stopping the rotary movement in the opening process. Particularly if the lid is adapted for re-closure of the container, it can be provided that the first projection also comes to bear against the edge of the discharge opening and is stopped in that way if the opening means, after the opening operation, is moved back into the starting position again or therebeyond.
In order to provide the first projection on the opening means, which co-operates with the inclined surface on the lid tab, in a fashion which is easy to manufacture, it can be provided that the first projection is in the form of a depressed bead, in particular a depressed bead in the second lid element, which in a starting position extends with its bead head into a depressed bead on the lid tab.
If the depressed bead and the raised bead of the inclined surface are oval, it may be desirable if they are arranged relative to each other in such a way that the large profile semi-axes are substantially tangential to a circular path on the lid tab. That design configuration is particularly advantageous if the opening means or the second lid element is mounted rotatably about the axis of the container body.

The invention also concerns a container lid for use for a container of a configuration as described. That container lid can include a first and a second lid element which can be of a configuration as described hereinbefore.
The object according to the invention is also attained by a method of opening a container comprising a container body of a material which is stable in respect of shape such as metal, PE or cardboard, having a primary opening which is closed by a metal plate portion as a first lid element, wherein in the opening operation for opening a discharge opening a separation line on the plate portion is broken open, which defines a lid tab, and for breaking open the separation line a first projection arranged on an opening means movable substantially parallel to the plate portion is guided along an inclined surface of the lid tab, whereby a force is produced on the lid tab substantially in a normal direction relative to the plate portion. The method according to the invention is distinguished in that the first projection in the opening operation is guided at least portion-wise along flanks of a depressed bead and a raised bead adjacent thereto. Preferably in the opening operation a venting means is moved together with the opening means in order to vent the container prior to breaking open the separation line of the lid tab. In that respect it may be desirable if a separation line on the lid tab is broken open for venting the container, that separation line defining a vent tab. In that respect the vent tab is broken open before the lid tab is broken open, thereby making the subsequent operation of opening the outlet opening easier.
The invention is described hereinafter by the description of an embodiment of a container according to the invention and further features according to the invention with reference to the accompanying drawings wherein:
Figure 1 shows a side view of a drinks can designed according to the invention, with fitted rotary lid, Figure 2 shows a plan view of the drinks can shown in Figure 1, Figure 3 shows a view on an enlarged scale of the region identified by III in Figure 1, Figure 4 shows a plan view of the drinks can of Figure 1 without the rotary lid, Figure 5 shows a section along line V-V in Figure 4, Figure 6 shows a plan view of the rotary lid, Figure 7 shows a section taken along line VII-VII in Figure 4, Figures 8a - c show the function of the elements on the can lid with the elements on the rotary lid by a section along line VIII-VIII in Figure 4, and Figures 9a - d show the function of the elements on the can lid with the elements on the rotary lid by a section along line IX-IX in Figure 4.
Figure 1 shows a side view of a drinks can 1 designed in accordance with the invention, as can be used in particular for carbonated drinks. The described can is of a re-closable design.
The can body 10 comprises tin plate and has a conical bottom portion 11 which goes into a surface for the can to stand on. In the upper region the can 1 tapers to afford a can neck 12, wherein the opening is closed by a plate portion 20 which is in the form of a can lid and which co-operates in that way with a second lid element in the form of a rotary lid in a manner still to be described. Figure 2 shows a plan view of the can of Figure 1, the details of the rotary lid not being illustrated here.
Figure 3 shows in detail the configuration of the closure of the drinks can 1 within the region III in Figure 1. As will be seen the plate portion 20 which is in the form of the first lid element extends beyond the edge of the can neck 12 and is gas-tightly connected thereto by means of a fold configuration. In the described example the plate portion is made from an aluminium sheet. Arranged over that first lid element is a rotary lid 50 which extends radially over the plate portion 20 and at the radial edge thereof extends downwardly substantially parallel to the axis of the container and engages over the fold configuration of the plate portion by means of peripherally spaced latching projections 51. The rotary lid 50 bears resiliently against the can lid 20 and is mounted rotatably relative thereto or relative to the can body 10, the axis of rotation being on the axis of the can body 10.

Figure 4 shows a plan view of the drinks can, with the rotary lid being removed. Figure 5 shows a corresponding view in section along line V-V in Figure 4. As already explained the plate portion 20 is fixed to the edge 13 of the can body or the can neck 12 by means of a fold 5 configuration 21. For that purpose at its radial edge the plate portion 20 has a plate portion collar 25 which bears snugly around the edge 13 of the can body. Inwardly relative to the container edge, the plate portion is shaped to provide an annular groove 22 which, to guide the rotary lid, receives an annular bead formed thereon. To reinforce the can lid it has a 10 reinforcing bead 23.
Arranged in the plate portion at a position outside the axis thereof is a circular lid tab 30 defined by an almost closed separation line 27. That separation line 27 is interrupted by a leg hinge 31. After the separation line 27 is broken open, the lid tab 30 opens the discharge opening in the can lid, in which case, in the opening operation, the lid tab is bent downwardly into the interior of the container in a manner to be described hereinafter, but still remains connected to the plate portion by way of the leg hinge 31.
In a first embodiment the separation line 27 is in the form of a score line which acts as a weakening line and which can be broken open by applying a force to the lid tab 30. Arranged within the lid tab 30 is a vent tab 40 defined by a further separation line 39 which is in turn of a configuration like the separation line 27. By virtue of the separation line 39 being broken open, the vent tab 40 opens a vent opening, wherein the vent tab 40 is non-losably secured to a leg hinge 42 in the same manner as the lid tab, even if the vent tab 40 moves downwardly into the can from the lid tab 30. Arranged on the vent tab 40 is an approximately circular raised bead in the form of a projection extending upwardly out of the drawing.
The edge of the vent tab 40 and thus the vent opening is completely within the lid tab 30.
In addition two beads 32, 36 which are oval in plan view are arranged in mutually adjacent relationship on the lid tab 30, wherein the long semi-axes thereof are each disposed substantially tangentially on a notional circle identified by IX-IX in the drawing. Starting from the base surface of the plate portion 20 or the lid tab 30 the depressed bead 32 extends projection-like into the interior of the container while the raised bead 36 extends upwardly out of the plane of the plate portion or the lid tab. The two beads 32, 36 are arranged relative to each other in such a way that the flank of the depressed bead 32 goes substantially without a transition into the flank of the raised bead 36, thereby providing a control surface acting as a ramp for a projection in order to generate an approximately axially directed force on the lid tab to break open the separation line 27. The axial height or depth of the beads are the same in the specified example so that ultimately it is possible to provide a ramp height which corresponds to double the height of an individual bead in the direction of the axis of the can.
Figures 6 and 7 now show the rotary lid 50 co-operating with the can lid 20. At the edge the circular rotary lid 50 has an annular groove 52 with which it embraces the folded configuration 21 of the can lid 20. Latching projections 51 serve for embracing the folded configuration 21, see Figure 5. In that respect the rotary lid 50 is secured against coming away from the can lid 20, while at the same time it is possible to provide for rotary movement of the rotary lid with respect to the can lid.
The rotary lid has a kidney-shaped opening 53 which, by rotation of the rotary lid relative to the can lid, can be aligned with respect to the discharge opening which is afforded by breaking open the separation line 27 and bending the lid tab 30 downwardly. The rotary lid 50 also has radially and peripherally spaced projections 54, 55 which are in the form of depressed beads, that is to say beads which extend into the plane of the drawing and serve as projections which co-operate with the raised bead 41 and the depressed bead 32 and the raised bead 36 respectively in the opening operation. In Figure 6 the respective curves denoting the positions of the projections 54, 55 are indicated by portions of a circle along which the projections pass in the rotary movement of the rotary lid.
Hereinafter reference is made to Figures 8a - c and 9a - d to describe the co-operation of the rotary lid 50 with the can lid 20 for opening and re-closing the can. In the starting position, that is to say when the separation lines 27, 39 have not yet been broken open, the rotary lid 50 is arranged in such a way that the projection 50 which extends in the direction towards the can lid engages into the depressed bead 32. In that respect the height of the depressed bead is such that the head of the projection 54 does not touch the bottom of the depressed bead. In the starting position the relative position of the can lid relative to the rotary lid is also distinguished in that the projection 54 is arranged spaced from the flank of the depressed bead 32 so that there is a free movement of the projection 54 within the depressed bead 32 during the rotary movement of the rotary lid, which takes place in the opening operation. That means that the projection 54 does not act on the flank 33 of the depressed bead in the first phase of the opening operation when moving the rotary lid. In the starting position however the projection 54 bears in the immediate proximity of, for example touching, the raised bead which is placed on the vent tab 40.
If now a rotary movement of the lid 50 is produced in the opening operation, then the projection 55 firstly co-operates with the raised bead of the vent tab 40 by the projection 55 being rotated against the raised bead 41 (see Figure 4). The projection 55 firstly contacts the flank of the raised bead 41 on the vent tab 40, whereby a force is exerted on the vent tab 40, which has a component in the normal direction to the plate portion 20.
Upon a further movement of the projection 55 towards the raised bead, the force increases until finally the separation line 39 breaks open and the vent tab 40 is urged downwardly into the container whereby the vent opening 43 is opened. Due to the described operation, an increased pressure in the drinks can can escape before the actual discharge opening is opened. Upon a continuing opening movement, that is to say rotation of the rotary lid 50, the projection 55 goes beyond the vent tab 40. The curve in respect of the position of the projection 55 for that movement is indicated in Figure 6 by the associated portion of the circle. Figure 8a shows the starting position of the rotary lid with respect to the projection 55, Figure 8b shows the situation during the opening operation and Figure 8c shows the situation in which the projection 55 has passed completely over the vent tab.

In a similar fashion Figures 9a - d show the operation of breaking open the separation line 27 for bending open the lid tab 40 whereby the discharge opening 35 is opened. The situation shown in Figure 9a again corresponds to the starting position of the rotary lid in which the separation iines 27, 39 are not yet broken open. The curve in respect of the position of the projection 54 for the movement thereof is indicated in Figure 6 by the associated portion of the circle. The projection 55 has the above-described free movement in the depressed bead 32, within which the projection can be moved without bearing against the flank 33 of the depressed bead 32.
Figure 9b shows precisely the situation in which the projection 54 and the flank 33 are in contact, which corresponds to a rotary position of the projection 54 shown in Figure 8b. When the projection 55 comes into engagement with the control surface formed by the flank 33 of the depressed bead and the flank 37 of the raised bead, the drinks can is ventilated, whereby the operation of breaking open the separation line is facilitated. As the two lids 50, 20 are arranged axially fixedly relative to each other at the edge of the drinks can, the force component which acts on the lid tab substantially parallel to the axis of the can and which is caused by the co-operation of the inclined surfaces 33, 37 with the projection 54 provides that the separation line 27 is broken open and, in the further movement of the projection 54 on the ramp on to the top of the raised bead 36, the lid tab 30 is urged inwardly into the drinks can, see Figure 9c. In the further rotary movement of the rotary lid 50 the projection 54 moves to the edge of the discharge opening 35, see Figure 9b. As the projection 54 extends over the edge of the discharge opening 35 into the can, that edge acts as a rotary abutment in the opening movement. After the conclusion of the opening operation in which the separation line 27 is completely broken open, the lid tab 30 is held by the leg hinge 31, see Figure 4.
Arranged at the edge of the discharge opening 35 is a sealing bead 26, see also Figure 4, which permits closure of the drinks can after the opening operation in which the rotary lid 50 is rotated back again to such an extent that the opening 53 thereof comes to lie outside the circular seal 26. In that case the sealing bead 26 which is disposed between the two lids 20, 50 bears in fluid-tight contact in relation to the two lids.
The depressed bead 32 and the raised bead 36 are arranged adjacent in such a way that they go directly into each other without a step and involve the same slope in the transitional region. The flank angle in the operative region of the inclined surface, that is to say in the region in which the projection 54 is in contact with the flanks 33, 37 is about 45 in the illustrated embodiment.
In the embodiment illustrated in the Figures the separation lines 27, 39 are in the form of score lines so that the metal is weakened there in order to be broken open as described. In an embodiment which is not illustrated, those separation lines can also be produced by the material in the can lid 30 being cut through to define the lid tab and the vent tab and by the plate portion being coated on the inside with plastic material, at least in the region of the cut lines. In that case, the projections 54, 55 co-operate with the respective control surfaces to break open that plastic material layer, in the opening movement of the rotary lid. In that respect it can also be provided that the edges of the opening of the lid tab or the opening of the vent tab respectively are enlarged radially inwardly by shaping, so that both tabs bear from the inside against the enlarged plate portion material. That ensures that even an increased internal pressure in the can cannot have the result that the tabs are moved outwardly beyond the plane of the plate portion, whereby under some circumstances the inwardly disposed plastic material layer could break open at the separation lines.

List of references 1 drinks can 10 can body 11 bottom portion 12 neck 13 edge plate portion, can lid 21 fold configuration 22 annular groove 23 reinforcing bead plate portion collar 26 sealing bead 27 separation line lid tab 31 leg hinge 32 depressed bead 33 flank of the depressed bead discharge opening 36 raised bead 37 flank of the raised bead 39 separation line vent tab 41 raised bead 42 leg hinge 43 vent opening rotary lid 51 latching projection 52 annular groove 53 opening 54 projection projection

Claims (23)

1. A container comprising a container body having a primary opening which is closed by a metal plate portion acting as a first lid element, wherein the metal plate portion includes a lid tab which is defined by a separation line and which after being broken open opens a discharge opening, and the lid tab has an inclined surface co-operating with a first projection arranged on an opening means movable substantially parallel to the plate portion for applying a force to the lid tab in order to break open the separation line, characterised in that the lid tab (30) has a depressed bead (32) and adjacent thereto a raised bead (36), wherein the inclined surface is composed at least of a portion of a flank (33) of the depressed bead and at least a portion of a flank (37) of the raised bead.

2. A container according to claim 1 characterised in that the depressed bead (32) and the raised bead (36) go into each other, wherein the transitional region is formed substantially without a bead bottom.

3. A container according to claim 1 or claim 2 characterised in that the depressed bead (32) and/or the raised bead (36) is or are substantially oval-shaped in plan view.

4. A container according to claim 1, claim 2 or claim 3 characterised in that bead depth of the depressed bead (32) is substantially equal in magnitude to the bead height of the raised bead (36).

5. A container according to one of claims 1 to 4 characterised in that the depressed bead (32) and the raised bead (36) are respectively introduced into the lid tab (30) in one shaping operation without the use of a hold-down arrangement.

6. A container according to one of claims 1 to 5 characterised in that the depressed bead (32) and/or the raised bead (36) in the operative region of the inclined surface with the associated first projection has or have a flank angle of 30° to 70°, in particular 40° to 50°.

7. A container according to one of claims 1 to 6 characterised by a venting means connected in respect of motion to the opening means for venting of the container prior to the separation line (27) defining the lid tab (30) being broken open.

8. A container according to claim 7 characterised by a vent tab (40) on the lid tab (30) which is defined by a separation line (39) extending on the lid tab, wherein the venting means includes a second projection (55) which in the movement of the opening means co-operates with the vent tab on the lid tab to produce a force extending substantially perpendicularly to the plate portion on the vent tab to break open the separation line (39) of the vent tab (30).

9. A container according to one of claims 1 to 8 characterised in that the first projection (54) which is arranged at the opening means and which is associated with the inclined surface (33, 37) on the lid tab (30) in its starting position before the separation line (27) of the lid tab is broken open projects into the recessed bead (32) and has therein a free travel, within which the first projection does not contact the inclined surface.

10. A container according to one of claims 8 and 9 characterised in that the second projection (55) which is arranged on the venting means and which is associated with the vent tab (40) in its starting position before the separation line (39) of the lid tab (40) is broken open is arranged in the immediate proximity of the vent tab.

11. A container according to one of claims 8, 9 and 10 characterised in that the vent tab (30) has a raised bead (41) which in plan view is in particular of a substantially circular configuration.

12. A container according to one of claims 1 to 9 characterised in that the plate portion (20) is connected to the container body (10) by a fold configuration (21), adhesive means or soldering means.

13. A container according to one of claims 1 to 12 characterised in that the opening means which is movable substantially in the plane of the plate portion for applying a force to the lid tab is in the form of a second lid element (50) which is arranged over the first lid element (20) and is mounted rotatably relative thereto, wherein the second lid element has an eccentric opening (53) which can be brought over the discharge opening (35) by rotation of the second lid element.

14. A container according to claim 13 characterised in that the second lid element (50) is rotatable relative to the container body about the axis thereof.

15. A container according to one of claims 1 to 14 characterised by a sealing means (26) which extends outwardly with respect to the separation line (27) of the lid tab (30) and around same and which is arranged in particular on the first lid element (20).

16. A container according to one of claims 1 to 15 characterised in that the first projection (54) after the separation line (27) of the lid tab is broken open, in the continuing rotary movement of the opening means relative to the container body (10), comes to bear against the edge of the discharge opening (35) whereby the rotary movement is stopped.

17. A container according to claim 15 or claim 16 characterised in that after the separation line (27) of the lid tab (30) is broken open, in a predetermined relative rotary position of the first and second lid elements (20, 50), the sealing means of the first lid element co-operates with the inside surface of the second lid element for sealing off the container.

18. A container according to one of claims 1 to 17 characterised in that the first projection co-operating with the inclined surface (33, 37) on the lid tab is provided on the opening means in the form of a depressed bead (54) which in a starting position extends with its bead top into a depressed bead (32) on the lid tab (30).

19. A container according to one of claims 3 to 14 characterised in that the depressed bead (32) and the raised bead (36) of the inclined surface (33, 37) are so arranged relative to each other that the large profile semi-axes thereof are substantially tangential to a circular path on the lid tab (30).

20. A container lid for a container comprising a container body of a material which is stable in respect of shape such as metal, PE or cardboard, which has a primary opening which is closed by a metal plate portion acting as a first lid element, wherein the metal plate portion includes a lid tab which is defined by a separation line and which after being broken open opens a discharge opening, and the lid tab has an inclined surface co-operating with a first projection arranged on an opening means movable substantially parallel to the plate portion for applying a force to the lid tab in order to break open the separation line, characterised in that the lid tab (30) has a depressed bead (32) and adjacent thereto a raised bead (36), wherein the inclined surface is composed at least of a portion of a flank (33) of the depressed bead and at least a portion of a flank (37) of the raised bead.

21. A method of opening a container comprising a container body of a material which is stable in respect of shape such as metal, PE or cardboard, having a primary opening which is closed by a metal plate portion as a first lid element, wherein in the opening operation for opening a discharge opening a separation line on the plate portion is broken open, which defines a lid tab, and for breaking open the separation line a first projection arranged on an opening means movable substantially parallel to the plate portion is guided along an inclined surface of the lid tab, whereby a force is produced on the lid tab, characterised in that the first projection (54) in the opening operation is guided at least portion-wise along flanks (33, 37) of a depressed bead (32) and a raised bead (36) adjacent thereto.

22. A method according to claim 21 characterised in that in the opening operation a venting means is moved together with the opening means in order to vent the container (1) prior to breaking open the separation line (27) of the lid tab (30).

23. A method according to claim 22 characterised in that for venting the container a separation line (39) is broken open on the lid tab (30), said separation line defining a vent tab (40).