EP0464061B1

EP0464061B1 - Tamper-evident push-in closure

Info

Publication number: EP0464061B1
Application number: EP90904731A
Authority: EP
Inventors: Peter Lewis Revill; Alan George Dalli
Original assignee: Broken Hill Proprietary Company Pty Ltd
Current assignee: Broken Hill Proprietary Company Pty Ltd
Priority date: 1989-03-17
Filing date: 1990-03-16
Publication date: 1994-12-21
Anticipated expiration: 2010-03-16
Also published as: KR920701004A; ZA902053B; ATE115935T1; EP0464061A1; AU634762B2; AU5282190A; CA2049066A1; EP0464061A4; DE69015351T2; WO1990011226A1; DE69015351D1; ES2066197T3; JPH04504093A

Abstract

A tamper-evident push-in easy-opening closure in a sheet metal container member comprising an opening (1) in the container member (2), an integral closure member (3) for the opening in overlapping and underlying relationship with the free edge portion (7) defining the opening (1), the free edge portion (6) of the closure member (3) being formed with spaced latch members (8, 9; 8', 9') dimensioned to engage the free edge portion (7) around the opening (1) to increase the push-in force required to open the closure member (3) to a level which ensures that sealant (S) for sealing the closure member (3) in the opening (1) is fully broken whenever the closure member is opened, said closure member (3) being formed with a central upstanding portion (5) dimensioned to be in close proximity to said free edge portion (7) and being substantially perpendicular to a rim (6) extending from said upstanding portion (5), to thereby restrict the entry of foreign objects through said closure without visibly opening said closure.

Description

The invention relates to push-in easy-open closure in a sheet metal container member comprising:
an opening in the container member;
an integral closure member for the opening formed by at least partially severing the container member to form the closure member and the opening, said closure member having a free edge portion terminating in a free edge, said free edge portion being disposed in a first stratum and in overlapping relationship with a free edge portion of said container member around said opening, said free edge portion of said container member being disposed in a second stratum and having a free edge, said first stratum underlying said second stratum;
sealant means applied to the closure member and to an adjacent portion of the free edge portion of said container member on an inside of the container member; and
at least one latch member formed at said free edge portion of said closure member, said at least one latch member including a narrow portion of the free edge portion of the closure member which has been displaced from said first stratum to increase a push-in force required to open said closure member such that said sealant means in broken when said closure member is opened, said latch member further substantially inhibiting said closure member resealing after opening.
A push-in easy-open closure of this type is disclosed in the document AU-A-444068. In this prior art closure, the free edge portions forming the latch members have been displaced from the first stratum to a position above the second stratum where they are in contact with or closely overlying the exterior surface of the free edge portion of the container member. This prevents the closure member from being opened by accidental contact or by atmospheric pressure. As a result of the rather basic construction of this closure, however, the opening force required is largely uncontrolled.
The present invention solves the problem of providing a push-in easy-open closure of the type indicated above which is so constructed that the opening force required to be applied to the closure is closely controlled.
According to the present invention, this problem is solved in that at least one latch member has been displaced from said first stratum to said second stratum to form an end face of the edge portion of said latch member which abuts against an end face of said free edge of said container member.
Owing to the abutting relationship with the end face of the free edge of the container member, the or each latch member forceably engages said free edge so that the force required to open the closure member is closely controlled.
In a preferred form, the or each latch member is formed in the closure member to define said edge portion of said latch member in a position inwardly of said closure member free edge to leave an adjacent portion of said closure member edge in underlying relationship with said free edge portion of said container member.
In a particularly preferred form of each of the above embodiments, the closure member is integrally connected to the container member by means of a narrow neck of metal defining a hinge connection for the closure member. The closure member is preferably formed with two angularly spaced latch members, each positioned at about 90° to 140° from the centre of the narrow neck of metal. In the case of small closure members, and some large closure members, only one latch member need be provided and it is preferably positioned directly opposite the hinge connection.
It is a concern of some beverage manufacturers that foreign substances may be introduced into the container through the push-in closure without being able to be visibly detected.
In a preferred form, therefore, the closure member is formed with a central upstanding portion and an outwardly extending rim portion which includes said free edge portion, said upstanding portion being dimensioned to be in such close proximity to said free edge portion of said container member to restrict the entry of foreign objects between said free edge portion of said container member and said closure member without visibly opening said closure.
The upstanding portion preferably has sides which are as close to the perpendicular to the rim as may be practically achieved. This further increases the difficulty in inserting an object between the closure member and the free edge portion surrounding the opening.
A preferred embodiment of the invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a fragmentary plan view of a can end having push-in easy-opening closure member of a prior art type modified in a manner which led to the present invention;
Figure 2 is a perspective view of the pouring closure of Figure 1;
Figures 3 and 4 are sectional elevations taken along the lines 3-3 and 4-4, respectively, in Figure 1;
Figures 5 and 6 are views corresponding to Figures 1 and 2 showing the preferred form of the invention;
Figures 7 and 8 are sectional elevations taken along the lines 7-7 and 8-8, respectively, in Figure 5, and
Figures 9 and 10 are views similar to Figures 5 and 7 showing a modified form of the embodiment of Figures 5 to 8.

Referring firstly to Figures 1 and 4 of the drawings, the closure member will be seen to comprise a generally circular pouring opening 1 and a smaller pressure releasing/venting opening 1a formed in a can end 2 by partially severing the sheet metal to form closure members 3 and 3a which are integrally connected to the can end 2 by means of narrow necks of metal 4 and 4a defining a hinge means for each closure member 3 and 5. An upstanding semi-circular bead B partly surrounds the pressure releasing closure 3a to protect it against inadvertent opening during handling. Since the closure members 3 and 3a are essentially the same in construction, only the pouring closure 3 will be further described below.
The closure members 4 and 5 formed with an upstanding domed portion 5 surrounded by an outwardly extending rim 6. The rim 6 is disposed in overlapping and underlying relationship with a free edge portion 7 of the can end around said opening 1 achieved by flattening a dome formed in said free edge portion 7 in the manner described in greater detail in the document AU-A-444 068. If desired, the closure member 3 may additionally be coined at the rim 6, prior to the flattening operation,to increase the diameter of the closure member 3 and increase the amount of overlap provided. The top of the dome 5 may also be coined to further increase the diameter of the closure member 3. In accordance with usual practice, the overlapping regions are covered by a suitable sealant S to hermetically seal the closure members 3 and 3a with respect to the openings 1 and 1a.
To enable inadvertent or surreptitious opening of the closure member to be readily detected, and to reduce undetectable access to the contents of the container by thin probes, the rim 6 of the closure is formed with two latch members 8 and 9 which overlap and overly the free edge portion 7 of the can end 2 at positions displaced about 120° from the centre of the hinge 4 in either direction. It will be appreciated that the latch members 8 and 9 may be located at other positions, such as at 90° from the centre of the hinge 4, or a single latch member may be located opposite the hinge 4.
In addition to the above, the diameter of the domed portion 5 is increased so that its side wall is as close as possible to the free edge portion 7 of the can end 2 and so that the side wall is as close as possible to perpendicular to the rim 6 thereby increasing the height of the dome 5 compared with prior art closures. In the present embodiment, the height of the dome 5 is of the order of 1.30 mm while the gap between the side wall of the dome 5 and the free edge portion 7 is only of the order of 0.5 mm, and may be as small as 0.25 mm. By virtue of the closeness of the side wall of the dome 5 to the free edge portion 7, its increased height and the steepness of the wall angle, great difficulty would be experienced in inserting even a small thin probe between the closure member 3 and the free edge portion 7 without significantly opening the closure member 3, and once opening occurs, the latch members 8 and 9 prevent reclosing so that opening is visually apparent.
The latches 8 and 9 shown in figure 4 which are similar to the claimed latches but do not correspond thereto are formed during or immediately after the sheet metal severing operation in which the closure member 3 and the opening 1 are initially defined. The closure member 3 is displaced below the free edge portion 7 prior to the flattening of the free edge portion 7 to reduce the diameter of the opening 1, while the latches 8 and 9, being upwardly inclined with respect to the remaining portion of the rim 6, as shown in Figure 4, are disposed in overlying relationship to the free edge portion 7 after flattening.
The amount of overlap between the latch members 8 and 9 and the free edge portion 7 shown in Figure 4 is exaggerated for clarity, but is selected to be sufficient to increase the opening force required to be approximately equal to the force required to rupture the sealant S which is applied to the inner face of the can end 2 in the region of the rim 6 and free edge portions 7. Since the latch members 8 and 9 are larger in effective diameter than the opening 1, the closure member 3 is not able to return to the fully closed position after opening. In this way, opening of the closure member 3 may be readily detected visually and the contents of the can will be more likely to leak from the can to provide further evidence of tampering.
In the preferred embodiment shown in Figures 5 to 8 of the drawings, the construction of the closure is essentially the same as in the preceding embodiment, with the exception that the latch members 8' and 9' are positioned in abutting relationship with the free edge portion 7 of the can end 2, in the manner shown most clearly in Figure 8 of the drawings. Since the rim 6 is usually in overlapping underlying relationship with the free edge portion 7, the latch members 8' and 9' forcibly engage the free edge portion 7 so that the force required to open the closure member 3 is increased sufficiently to ensure that closure member 3 will be fully opened by the application of the necessary push-in force. Accordingly, opening of the closure member 3 will be much more visible than in the past, and the contents of the can will tend to leak from the can as further evidence of its opening. In Figures 6 and 7, the height of the latch means 8' and 9' has been exaggerated for clarity.
The embodiment of Figures 5 to 8 is presently preferred as it performs acceptably in practice and is not as noticeably different from a standard prior art construction as the embodiment of Figures 1 to 4. However, in this embodiment, the flattening of the free edge portion 7 to produce the necessary overlap can result in displacement of the closure 3, caused by the flattening of the hinge region 4, causing unacceptable binding of the latch means 8' and 9'. To reduce this effect, the radial sever lines L defining the hinge 4 (and the hinge 4a) are extended as shown in broken outline in Figures 1 and 2, to allow this part of the metal to absorb some of the free metal resulting from the flattening operation, and reducing the displacement of the closure 3 to acceptable levels.
In the embodiment shown in Figures 9 and 10 of the drawings, the closures 3 and 3a (not shown) are each formed with additional abutments 10, which are similar in appearance to the latch means 8' and 9' but are not fully formed to engage the free edge portion 7, as shown most clearly in Figure 10 of the drawings. The purpose of the abutments 10 is to further deter the insertion of small thin probes, which must be angularly inserted at the periphery of the opening 3 in a sliding motion around the periphery. The abutments 10 and the latches 8' and 9' prevent this sliding motion and further deter such activities.

Claims

A push-in easy-open closure in a sheet metal container member (2) comprising:
an opening (1, 1a) in the container member (2);
an integral closure member (3, 3a) for the opening (1, 1a) formed by at least partially severing the container member (2) to form the closure member (3, 3a) and the opening (1, 1a), said closure member (3, 3a) having a free edge portion (6) terminating in a free edge, said free edge portion (6) being disposed in a first stratum and in overlapping relationship with a free edge portion (7) of said container member (2) around said opening (1, 1a), said free edge portion (7) of said container member (2) being disposed in a second stratum and having a free edge, said first stratum underlying said second stratum;
sealant means (S) applied to the closure member (3, 3a) and to an adjacent portion of the free edge portion (7) of said container member (2) on an inside of the container member (2); and
at least one latch member (8', 9') formed at said free edge portion (6) of said closure member (3, 3a), said at least one latch member (8', 9') including a narrow portion of the free edge portion (6) of the closure member (3, 3a) which has been displaced from said first stratum to increase a push-in force required to open said closure member (3, 3a) such that said sealant means (S) in broken when said closure member (3, 3a) is opened, said latch member (8', 9') further substantially inhibiting said closure member (3, 3a) resealing after opening,
characterized in that
said at least one latch member (8', 9') has been displaced from said first stratum to said second stratum to form an end face of the edge portion of said latch member (8', 9') which abuts against an end face of said free edge (7) of said container member (2).
The closure according to claim 1, characterised in that the or each latch member (8', 9') is formed in the closure member (3, 3a) to define said edge portion of said latch member (8', 9') in a position inwardly of said closure member free edge (7) to leave an adjacent portion of said closure member edge (6) in underlying relationship with said free edge portion (7) of said container member (2).
The closure of claim 1 or 2, characterised in that said closure member (3, 3a) is integrally connected to the container member (2) by means of a narrow neck (4, 4a) of metal defining a hinge connection for the closure member (3, 3a).
The closure of claim 3, characterized in that two angularly spaced latch members (8', 9') are each positioned at about 90° to 140° from the centre of the narrow neck (4, 4a) of metal.
The closure of claim 3, characterised in that one latch member is positioned substantially opposite said hinge connection.
The closure according to any one of claims 3 to 5, characterised in that upstanding abutments (10) are formed in said closure member edge (6) at positions spaced from but adjacent to said narrow neck (4, 4a) of metal, that said abutments (10) are of similar form to said latch members (8', 9') but are not fully formed to abut said free edge portion (7) of said container member (2), and in that said abutments (10) are positioned to further deter insertion of small thin probes between said closure member (3, 3a) and said free edge portion (7) of said container member (2).
The closure of any preceding claim, characterised in that said closure member (3, 3a) is formed with a central upstanding portion and an outwardly extending rim portion which includes said free edge portion (6), and in that said upstanding portion is dimensioned to be in such close proximity to said free edge portion (7) of said container member (2) to restrict the entry of foreign objects between said free edge portion (7) of said container member (2) and said closure member (3, 3a) without visibly opening said closure.
The closure of claim 7, characterised in that the sides (5) of said upstanding portion are substantially perpendicular to said rim (6).