EP0592550A4

EP0592550A4 - Full open can end closure.

Info

Publication number: EP0592550A4
Application number: EP92914746A
Authority: EP
Inventors: John Alan Walmer Slade; Dietmar Salm
Original assignee: Broken Hill Pty Co Ltd
Current assignee: Broken Hill Pty Co Ltd
Priority date: 1991-07-11
Filing date: 1992-07-10
Publication date: 1995-07-19
Anticipated expiration: 2012-07-10
Also published as: CA2113338A1; EP0592550B1; WO1993001096A1; EP0592550A1; NZ243519A; ATE152413T1; DE69219473D1; JPH06509045A

Abstract

A can end closure comprises (i) a panel formed with a rim portion (2) and (ii) a central panel (4) substantially fully severed from the rim portion (2) and having a peripheral free edge portion (5). The rim portion is formed with spaced parallel folded portions (F1 and F2) defining a groove G within which the peripheral free edge portion (5) of the central panel (4) is positioned. Sealant (8) hermetically seals the central panel (4) to the rim portion (2). A push-in closure C in the central panel (4) comprises a closure tab (10) severed from the panel (4) along line (11) except for a hinge portion (12) and has a peripheral free edge portion (14) in overlapping underlying relationship with an edge portion (15) of the central panel (4). A latch means (17) formed in the edge portion (14) and engaging the free edge of the edge portion (15) prevents unintended inward movement of the tab (10). Sealant (18) hermetically seals the push-in closure C. An inwardly direct abutment (19) formed in the central panel (4) adjacent the closure C opposite the hinge portion (12) comprises a substantially vertical wall portion that defines an anchor point for the tip of the bowl of a spoon inserted in the opening formed in the central panel (4) by inward displacement of the closure C and prevents withdrawal of the spoon as the spoon is levered against the rim portion (2) to deform the central panel (4) and remove it from the rim portion (2). The position of the peripheral free edge portion (5) between the folded portions (F1 and F2) facilitates easier removal of the central panel (4) from the rim portion (2) with a less variable removal force than was required with prior art constructions.

Description

FULLOPENCANENDCLOSURE

Field of the Invention:

This invention relates to closures for containers, and more particularly to closures of the full-open end type in which substantially all of the end panel is removed when the closure is opened. Background of the Invention:

Most full-open ends currently in use include an end panel which is scored or weakened along a line extending adjacent the rim of the end which is seamed to the can body. The use of scored end panels has at least two major shortcomings. In the first place, the scoring operation cannot be closely controlled to the extent necessary to achieve easy rupture for end removal whilst preventing perforation of the end panel to avoid leakage of contents from the can or leakage of air into the can. It will be appreciated that the leakage of air into a can may have serious consequences in the case of food products, and may spoil other canned products.

In the second place, scored end panels of the above described type leave sharp edges on the retained edge portion of the end panel and on the edge of the removed disc. These sharp edges present a risk in that the fingers of the user may be cut handling the can or the removed disc after opening.

While the latter problem may be reduced by the formation of complex multiple folds in the panel edge structure which serve to protect the raw edges after opening, this increases manufacturing and material costs and does not address the first defect described above. Examples of typical full-open end closures of the above types may be found in the Patent literature. It will be noted that closures of this type require a retained lever mechanism by means of which the initial rupturing of the score line is achieved, the lever mechanism usually having a finger opening by means of which the opening disc may be removed from the end panel. Such opening devices are often extremely difficult to manipulate and require a considerable force to be applied to cause the initial rupturing of the score line. Such manipulation is often difficult to achieve, particularly for a woman or child.

The Patent literature contains limited examples (e.g. U.S. Patent 4003495 and EPO 377788A) of full-open end closures which utilize readily available domestic implements, such as spoons, as levers to assist in opening the end panel. In the first of the above examples, the removal end panel is formed with a push- in end closure through which a spoon may be inserted to lever the end panel upwardly to break the tear line defining the removable panel. The tear line is defined in this example as being formed by shear-coining and swaging a convex surface of the can end. As far as the present applicant is aware, this process has not been commercially adopted by the can making industry, and it is expected that the process involved in forming the tear line would be difficult to consistently perform in practice to ensure a consistent opening force while avoiding rupture of the closure under the high pressures to which cans of food are subjected during the processing of canned food products.

The second of the above examples utilizes a weakening line in the form of a V-shaped nick, and the spoon is described as engaging an external groove formed in the end to rupture the score and lever the panel from the end. Experiments conducted prior to the present invention caused the applicant to abandon the use of scored panels on the ground that it is too difficult to rupture the score line using a spoon as a lever, especially where the end is made from steel. In any event, this construction has the same problems of variable opening force and penetration of the end panel by the score line referred to above. It will be appreciated that if the opening force was too high, the construction described would suffer from the problem of the spoon tip tending to slip from the groove during attempts to rupture the score line. Once again, as far as the applicant is aware, this construction has not found its way into commercial production. Summary of Invention and Object:

It is an object of the present invention to provide an improved full-open closure for a container member, such as a can end, in which the above described problems are at least ameliorated.

The invention therefore provides a closure for a container member, such as a can end, comprising a panel formed with a rim portion and a central panel adapted for at least substantial removal from the rim portion, said central panel being at least substantially fully severed from said rim portion and having a peripheral free edge portion, said rim portion having a first fold defining an inner free edge portion and a second oppositely directed fold defining an edge portion which extends in a spaced generally parallel relationship with said inner free edge portion, said peripheral free edge portion of said central panel being positioned in overlapping relationship with and between said inner free edge portion and said parallel edge portion to prevent displacement of said central panel outwardly or inwardly of said rim portion during processing and handling, sealant means hermetically sealing said peripheral edge portion of said central panel with respect to said rim portion,and means associated with said central panel for enabling said central panel to be deformed to disengage it from its overlapping relationship with said rim portion to remove said central panel from said rim portion.

Since the central panel is at least substantially fully severed from the rim portion, the severed free edges of the central panel and the rim portion can be formed so as to substantially reduce the likelihood of sharp edges. It is possible to control the severing operation to produce resultant free edge portions which are essentially burr-free or blunt whereby the second problem associated with scored structures is avoided. Since the central panel is hermetically sealed with respect to the rim portion, the leakage problems referred to above are either avoided or are relatively easy to detect during the manufacturing process.

Since the central panel is in overlapping relationship with the rim portion, the closure is able to withstand the high pressures to which canned foods are normally subjected during the cooking/sterilizing processes which are commonly used in the canned food industry.

In a preferred form of the invention described in greater detail below, the second oppositely directed fold is positioned in underlying relationship with said inner free edge portion and said peripheral free edge portion of said central panel is positioned in overlapping and underlying relationship with said inner free edge portion and in overlapping overlying relationship with said parallel edge portion. The advantage of this construction is that the free edge of the parallel edge portion can be hidden under the inner free edge portion and the sealant means is applied to the hidden inner face of the container member.

In view of the practical importance of ensuring that the central panel is hermetically sealed with respect to the rim portion, it is preferred to construct the closure so that the peripheral free edge portion of the central panel is positioned to provide a gap between at least the parallel edge portion and the peripheral free edge portion to facilitate entry of sealant material.

The closure is most preferably constructed to position said peripheral free edge portion substantially centrally between the inner free edge portion and the spaced generally parallel edge portion formed by the first and second folds, to assist the sealant means adequately penetrating at least the overlapping portions of the peripheral free edge portion and the spaced parallel edge portion defined by the second fold. In a particularly preferred form of the invention, the peripheral free edge portion of the central panel is formed with upwardly and downwardly projecting raised portions which are adapted to engage the inner free edge portion and the spaced parallel edge portion to substantially centralize the peripheral free edge portion between these edge portions. One convenient way of achieving this construction is to form spaced pairs of oppositely directed dimples in the peripheral free edge portion of the central panel. Although it is preferred that the central panel should be fully severed from the rim portion of the container member, some uses of the end closure may require the central panel to be retained to the rim portion by a narrow neck of metal constituting a hinge about which the central panel may be bent to open the end closure. Furthermore, the central panel may remain connected to the rim portion during the necessary metal forming operations by means of several narrow easily ruptured metal bridges which are broken when the panel is deformed during the implement levering operation.

The means associated with the central panel may comprise ring-pull device by means of which an opening force is applied to the central panel. For manufacturing and environmental reasons, the means preferably comprises a closure formed in the central panel and shaped to be opened by and to receive an opening implement for levering engagement with the rim portion to thereby deform the central panel to disengage it from the rim portion.

The closure means formed in the central panel is preferably a push-in closure and may take any one of a number of different forms, including a scored push-in closure or a fully severed closure of the type described in our United States Patents Nos. 3,759,206, 3,931,909 and 4,155,480. A fully severed closure of this type is preferred, and although a scored closure may suffer from the first difficulty outlined above, this difficulty could be overcome by the application of sealant to the scored region. Where a severed push-in closure is used, it will comprise a tab portion severed from the central panel except for a neck of metal defining a hinge and overlapping and underlying the edge portion of the central panel surrounding the opening created by the severing operation. The push-in closure tab and/or the edge portion of the central panel surrounding the opening is cold worked to produce the overlapping relationship either in the manner described in the aforementioned patents and/or by suitable coining operations known in the art.

Where the end closure is to be used in a container for products which create a vacuum within the.container, the push-in closure can be formed with^' latch members of the type described in our co-pending International Patent Application No. PCT/AU90/00108 (U.S. Patent Application Serial No. 768739) to prevent the external air pressure pushing the closure tab into the open position, and to make it evident that the closure has been opened or in some way tampered with.

The push-in closure member is preferably shaped to receive a suitable implement of the type which is likely to be available when the container is being opened. In the case of a container for pet food, or some other food product, the most convenient implement is a spoon, and the closure member is most suitably shaped to receive the bowl of the spoon which is then levered against the rim of the container to deform the central panel and withdraw it from its underlying relationship with the rim portion.

In a further preferred form of the invention, the end is formed with an inwardly directed abutment or dimple located centrally of the or each closure and adjacent the edge portion surrounding the opening opposite the hinge. The dimple is preferably dimensioned to provide an anchor point for the tip of the bowl of a spoon, or other implement, inserted in the opening, to reduce the likelihood of the implement withdrawing from the opening as it is levered against the rim. In this way, the spoon or other implement operates securely to lever the central panel from its rim portion.

Brief Description of the Drawings:

In order that the invention may be more readily understood, a presently preferred embodiment of the invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a plan view of a can end embodying the invention;

Figure 2 is a fragmentary sectional elevation of the can end taken along the line 2-2 in Fig. 1;

Figure 3 is an enlarged fragmentary sectional elevation of the closure formations shown in Fig. 2;

Figure 4 illustrates one method of opening the can end of Figs. 1 to 3.

Figures 5A to 5G illustrate the steps involved in one method of forming the can end embodying the invention, and a fragmentary sectional elevation of an alternative closure construction embodying the invention. Description of Preferred Embodiments:

Referring firstly to Figures 1 and 2 of the drawings, the can end 1 embodying the invention comprises a rim portion 2 having an inwardly directed or inner free edge portion 3 and a central panel 4 having a peripheral free edge portion 5, which has been fully severed from the rim portion 2, disposed in overlapping and underlying relationship with the free edge portion 3 of the rim portion 2.

The inner free edge portion 3 of the inner portion 2 is defined by a first underlying folded portion F_t, and a second spaced parallel folded portion F₂ is formed in underlying relationship with the first folded portion F. and terminates in an edge E, positioned outwardly of the edge portion 3, to define a continuous groove G within which the peripheral free edge portion 5 of the central panel 4 is received.

In a particularly preferred form of the invention, the peripheral free edge portion 5 of the central panel 4 is formed with pairs of oppositely directed small dimples 6, 7 spaced equidistantly around the periphery of the free edge portion 5, as shown most clearly in Figure 1 of the drawings. As will be evident from Figures 2 and 3 of the drawings, the dimples 6, 7 cause the peripheral free edge portion 5 of the central panel 4 to be positioned substantially centrally between the folded portions FI and F2. In this way, the sealant material 8 which is applied to the overlapping regions of the panel 4 and rim portion 2 is able to penetrate the region between the peripheral free edge portion 5 and at least the folded portion F2 to ensure that a proper hermetic seal is formed (see Fig. 3) .

To further ensure that a proper volume of sealant 8 is retained in the overlapping regions, the central panel 4 is formed with a continuous downwardly extending rib 9 which creates a barrier or reservoir which prevents movement of the sealant 8 towards the centre of the central panel 4 when the sealant is applied to the end 1 by any suitable method, such as that described in further detail below.

The central panel 4 is formed with a push-in easy opening closure C comprising a downwardly dished closure tab 10 which is fully severed from the panel 4 along line 11 to leave a hinge portion 12, and having a free edge portion 14 disposed in overlapping and underlying relationship with an edge portion 15 surrounding the opening 16 created by the severing operating. The closure C is formed, at free edge portion 14 of the closure tab 10, with spaced latch means 17 which frictionally engage the edge 11 of the edge portion 15 to inhibit movement of the tab 10 inwardly of the panel 4 and/or to provide an indication of opening or tampering, as shown most clearly in the enlarged sectional elevation of Figure 3. A sealant material 18 is applied to the overlapping regions of the edge portions 14 and 15 to hermetically seal the closure C in the central panel 4.

The closure tab 10 is dished in the manner shown and the opening 16 is shaped to receive the tip the bowl B of a spoon S in the manner shown in Figure 4 of the drawings. The shape of the opening 16 has also been designed to relieve points of weakness in the design of the closure C when the can end 1 is subjected to internal pressure, when fitted to a can, such as will occur when canned food products are processed for cooking and/or sterilizing.

During the opening operation, the bowl B of the spoon S is forced into the dished closure tab 10, forcing the tab 10 open past the latch means 17, breaking the sealant 18 and bending the tab 10 about the hinge 12, all as shown in Figure 4 of the drawings.

To ensure that the bowl B of the spoon S, or other similar implement, is maintained in the opening 16 during the levering operation necessary to remove the central panel 4 from the rim portion 2, the central panel has an inwardly directed abutment or dimple 19 formed in the central panel 4 centrally of the closure C opposite the hinge 12 and adjacent the edge portion 11 surrounding the opening 16 of the closure C. The dimple 19 is shaped to provide a vertical rear wall 20, and is dimensioned to be received in the tip portion of the bowl B, as shown in Fig. 4, with the wall 20 defining an adequate anchor point for the tip of the bowl B inserted in the opening 16 as it is levered against the rim 2, in the manner shown clearly in Figure 4 of the drawings, to deform the end panel 4 and remove the free edge portion 5 of the panel 4 from its underlying relationship with the free edge portion 3 of the rim portion 2. The anchor point provided by the dimple 19 operates to prevent the bowl B of the spoon S withdrawing from the opening 10 as the spoon S is levered against the rim 2.

It will be appreciated that without the dimple 19, the spoon may have a tendency to slide against the underside of the central panel 4 without adequately deforming the central panel 4 to facilitate removal of the panel from the rim. A similar tendency would be present in the case of the construction described in prior U.S. Patent 4003495, in which the rim of the bowl of the spoon engages the portion 32 which extends around the periphery of the closure 28 thereby creating extremely narrow frictional contact points between the bowl and the panel 16. In the present embodiment, the dimple 19 operates to inhibit relative sliding movement between the spoon S and the central panel 4 to ensure that the central panel 4 is properly deformed to allow its removal from the rim 2.

As described above, both the central panel 4 and the closure tab 10 are hermetically sealed with respect to the rim portion 2 and - the edge portion 15 respectively by means of the application of sealant 12 and 18, such as a suitable plastisol, applied in any suitable manner known in the art, such as by an apparatus of the type described in our United States Patents Nos. 4102304, 4151314 and 4842469.

The above described closures are formed by suitable metal working operations, known in the art, for example as schematically illustrated in Figures 5A to 5G of the drawings. Figure 5A shows a typical can end shell on which the metal working operations necessary to form the above described closures are performed. In Figure 5B, the end shell is reformed to have a substantially vertical rim wall and the sealant retaining rib 9 is formed along with a central panel configuration which allows for expansion under internal pressure during canned food processing. It is also preferred that the dimples 6 and 7 are formed in the modified end shell, although they may alternatively be formed in a subsequent operation before the next step.

The next step is shown in Figure 5C and comprises shearing the central panel 4 from the rim portion 2. The left side of Figure 5C shows the position of the sheared elements at the bottom stroke of the die operation, while the right side of Figure 5C shows the position at the upstroke of the die operation. As mentioned above, the shearing operation is performed so as to produce essentially burr-free or blunt free edges to thereby avoid the problems associated with sharp or jagged edges of the type produced when scored metal is severed.

The previously substantially vertical side wall of the rim 2 is formed with an inwardly directed bend which constitutes the commencement of the fold F., the fold F₂ already having been partially formed by the bend in the panel at the bottom of the vertical side wall. If desired the side wall of the end shell may have a commencement of the first fold F. preformed by a rolling operation during or immediately after the formation of the curled edge in the edge portion 2, for example, as part of the commencement ring curling operation. This preforming operation assists the fold formation referred to above.

In Figure 5D, the size of the central panel is expanded by reducing the angle of the portion between the free edge portion 5 and the remainder of the central panel 4, and the folded portion Fl is further formed by collapsing the side wall of the rim 2 about the existing bends.

In Figure 5E, the double fold F., F₂ has been flattened into its final form to capture the peripheral free edge portion 5, and in Figure 5F the closure tab 10 is severed along the line 11, the latch means 17 are formed in the free edge portion 16 of the tab 10 and the spoon engaging dimple 19 is formed. In the final working operation of Figure 5G, the tab 10 is coined to cause the free edge portion 14 to overlap and underly the free edge portion 15 and the latch means 17 to frictionally engage the edge of the opening 11. Sealant is then applied to the end at 8 and 18 and any necessary repair lacquer may also be applied to the exposed worked areas of the end 1. While the embodiment shown in Figures 1 to 5 has the folded portions, F_{l f} F₂ of the rim portion 2 located below the free edge portion 3, it may be acceptable in certain applications for the folded portions F,, F₂ to be disposed above the free edge portion 3, in the general manner shown schematically in Figure 6 of the drawings. In such an arrangement, the sealant shown protects the sheared edge of the rim portion 2 against corrosion, and while the free edge is exposed, its generally blunt configuration will prevent any serious risk of injury to the user.

The central panel 4 may be formed in any desired profile, such as shown in the drawings, to allow the central panel 4 to flex outwardly and inwardly during internal pressure changes caused by processing of the contents of the can. The profile of the central panel 4 may also be designed in a manner not shown to facilitate deformation of the central panel 4 along particular lines to facilitate easy removal of the central panel 4 from the rim portion 2.

Furthermore, the central panel 4 may be formed so that the panel is upwardly domed in its related state. In this way, loss of vacuum or more accurately, leakage of air into the can, may be visually detected.

While in the above described embodiments, the sealant S is applied externally after the closure has been formed, it will be appreciated that sealant material could be applied to portions of the rim 2 so that the free edge portion 5 of the central panel 4 is clamped between sealant covered surfaces to form the necessary hermetic seal or to form a further seal in addition to the sealant applied as described above.

While the closure 10 is dished in the embodiment shown, it can alternatively be essentially flat with an upstanding bend around the free edge portion 14 to assist in the formation of the latches 17 and to provide an engagement point for the spoon S during the opening operation.

Claims

1. A closure for a container member, such as a can end, comprising a rim portion and a central panel adapted for at least substantial removal from the rim portion, said central panel being at least substantially fully severed from said rim portion and having a peripheral free edge portion, said rim portion having a first fold defining an inner free edge portion and a second oppositely directed fold defining an edge portion which extends in a spaced generally parallel relationship with said inner free edge portion, said peripheral free edge portion of said central panel being positioned in overlapping relationship with and between said inner free edge portion and said parallel edge portion to prevent displacement of said central panel outwardly or inwardly of said rim portion during processing and handling, sealant means hermetically sealing said peripheral edge portion of said central panel with respect to said rim portion, and means associated with said central panel for enabling said central panel to be deformed to disengage it from its overlapping relationship with said rim portion to remove said central panel from said rim portion.

2. The closure of claim 1, wherein the second oppositely directed fold is positioned in underlying relationship with said inner free edge portion and said peripheral free edge portion of said central panel is positioned in overlapping and underlying relationship with said inner free edge portion and in overlapping overlying relationship with said parallel edge portion.

3. The closure of claim 1 or 2, wherein the overlapping portions of said rim portion and said peripheral free edge portion are constructed to position said peripheral free edge portion to provide a gap between at least said parallel edge portion and said peripheral free edge portion to facilitate the penetration of sealant means into said gap.

4. The closure of claim 3, wherein said overlapping portions of said rim portion and said peripheral free edge portion are constructed to position said peripheral free edge portion substantially centrally between said inner free edge portion and said parallel edge portion. 5. The closure of claim 3 or 4, wherein said positioning of said peripheral free edge portion is provided by projections extending from at least one of said parallel edge portion, said peripheral free edge portion and said inner free edge portion.

6. The closure of claim 5, comprising pairs of projections extending from opposite faces of said peripheral free edge portion, said pairs of projections being spaced about the periphery of said peripheral free edge portion to substantially centrally position said peripheral free edge portion between said folded portions.

7. The closure of any preceding claim, further comprising means assosicated with said central panel to retain the sealant means in the region of said overlapping portions of said rim portion and said peripheral free edge portion.

8. The closure of claim 7 wherein said sealant retaining means comprises a downwardly directed peripheral rib formed in said central panel inwardly of and adjacent said peripheral free edge portion,said rib extending to a position below said parallel edge portion.

9. The closure of any preceeding claim, wherein the means associated with said central panel comprises a closure formed in said central panel adjacent said rim portion and shaped to be opened by and to receive an opening implement for levering engagement with said rim portion to deform the central panel and facilitate its disengagement from said rim portion.

10. The closure of claim 8, wherein said closure in said central panel comprises a push-in closure shaped to receive said opening implement under said central panel.

11. The closure of claim 10, wherein said push-in closure comprises a severed closure tab having a free edge portion in overlapping and underlying relationship with said central panel and an unsevered portion defining a hinge about which said tab is bent when said push-in closure tab is opened, and sealant means hermetically sealing said closure tab with respect to said central panel.

12. The closure of claim 11, further comprising latch means formed in said free edge portion of said closure tab and frictionally engaging said central panel to inhibit unintended opening movement of said closure tab.

13. The closure of any one of claims 10 to 12, wherein said push-in closure is shaped to receive the bowl of a spoon which is levered against the rim portion to deform and remove said central panel from said rim portion.

14. The closure of claim 13, further comprising an inwardly directed abutment formed in said central panel adjacent said push-in closure, said abutment being shaped and positioned to serve as an anchor point for the bowl of the spoon to inhibit withdrawal of the spoon from engagement with the central panel during the levering operation.

15. The closure of claim 14, wherein said abutment comprises an inwardly directed dimple in the central panel closely adjacent the push-in closure, said dimple having a substantially vertical rear wall portion against which the tip of the bowl of the spoon engages to prevent withdrawal of the spoon from the push-in closure.

16. A method of forming a closure in a container member, such as a can end, comprising a rim portion and a central panel adapted for at least substantial removal from said rim portion, comprising the steps of substantially severing said central panel from said rim portion, forming a first fold in said rim portion to define an inner free edge portion and a second oppositely directed fold to define an edge portion which extends in a spaced generally parallel relationship with said inner free edge portion, expanding said central panel to locate a peripheral free edge portion thereof in overlapping relationship between said inner free edge portion and said parallel edge portion, and applying sealant means in the region of said overlapping portions to hermetically seal the peripheral free edge portion with respect to said rim portion.

17. The method of claim 16, further comprising- the step of maintaining a gap between said peripheral free edge portion and at least said parallel edge portion to facilitate the penetration of sealant means into said gap.

18. The method of claim 17, comprising the step of forming peripherally spaced abutments extending from at least one face of said peripheral free edge portion to create said gap.

19. The method of claim 17 comprising the step of forming abutments extending from opposite faces of said peripheral free edge portion to position said peripheral free edge portion subtantially centrally of said inner free edge portion and said parallel edge portion.

20. The method of any one of claims 16 to 19, further comprising the step of forming a push-in closure in said central panel adjacent said rim portion.

21. The method of claim 20, further comprising the step of forming an inwardly directed abutment adjacent said push-in closure, said abutment being positioned and shaped to be engaged by the tip of the bowl of a spoon inserted through said push-in closure to prevent withdrawal of said spoon from said closure when said spoon is levered against said rim portion to deform said central panel and remove it from said rim portion.