Bottles and jars – Closures – Frangible member or portion
Reexamination Certificate
1998-07-09
2001-12-11
Cronin, Stephen K. (Department: 3727)
Bottles and jars
Closures
Frangible member or portion
Reexamination Certificate
active
06328175
ABSTRACT:
The subject of the present invention is a mould for the production of tamperproof caps having tabs turned up in the mould, as well as a cap formed in such a mould.
One solution for making a screw cap, having a top and a threaded skirt, tamperproof is to provide the threaded skirt, on its free edge opposite the top of the cap, with a tamperproof ring. The latter includes tabs turned up towards the top of the cap and interacting with an annular rib made on a bottle intended to receive the cap. The tamperproof ring is linked to the skirt by breakable linking elements. Thus, on first opening the bottle, when the cap is unscrewed for the first time, the tabs come into abutment against the annular rib on the bottle, thus making is impossible to follow the cap in its translational movement. The breakable linking elements are then broken. This irreversible breaking makes it possible to see that the bottle has already been opened at least once.
French Patent FR-2,525,565 describes a cap of this type.
In order to produce such a cap, it is known to use a three-part mould: a movable part or mould top matching the external shape of the cap without the tamperproof ring, a stripping part or stripper ring matching the external shape of the tamperproof ring and a fixed mould core matching the internal shape of the cap and of the tamperproof ring.
With such a mould, it is possible to remove the cap from the mould without unscrewing, by removing the movable part and the stripper ring away from the fixed core in a translational movement. On demoulding, the tabs are forced into a radial position pointing towards the inside of the tamperproof ring. This position is undesirable. The tabs are then turned up in such a way that they are almost parallel to the skirt and to the tamperproof ring, the tabs pointing towards the top of the cap. In order to bring the tabs into the desired position, the tamperproof ring and the cap which is fastened to it are moved closer to the core in such a way that the tabs are bent up towards the inside of the cap by the core of the mould.
During this operation of bending the tabs up, the assembly formed by the cap and the tamperproof ring is only held in place on the tamperproof ring by the stripper ring. This is because the part of the mould must be removed at the start of the demoulding operation in order to allow deformation of the cap when it is removed from the core in a translational movement. During the bending-up operation, it sometimes happens that the cap inclines, thus making it impossible for all the tabs to be bent up. This inclination is encouraged by a slight clearance which is formed between the stripper ring and the tamperproof ring during demoulding. This clearance is due to the contraction of the material of which the tamperproof ring is made as a result of it cooling.
The object of the invention is therefore to prevent the assembly formed by the cap and the tamperproof ring from inclining during the operation of bending up the tabs. It is hence a question of providing better retention of this assembly in the stripper ring.
For the purpose, the invention provides a mould and a cap intended to be produced in this mould.
The mould according to the invention is of the mould type for forming a cap having a cylindrical skirt, this skirt being provided with at least one screw thread and closed off at one end by a top, as well as a tamperproof ring linked to the free end of the skirt by breakable linking elements, the tamperproof ring including tabs intended to interact with an annular rib situated on the neck of a container intended to receive the cap, having a movable part or mould top, the internal wall of which corresponds to the external surface of the skirt and of the top, a stripping part or stripper ring, the inner surface of which corresponds to the external surface of the tamperproof ring, and a core, which is designed to be removed, by a translation movement but with no rotation, the external surface of the core corresponding to the internal surface of the top, of the skirt and of the tamperproof ring.
According to the invention, the stripper ring has, on the side facing the top of the mould, on the lower edge of the skirt and in at least two separate places, at least one notch and/or at least one projection so as to create a mortise-and-tenon linkage between the skirt and the stripper ring during moulding and demoulding of the cap.
In this way, perfect stability of the cap is ensured. This is because, during moulding, the material making up the cap matches the shape of the mould, especially the shape of the stripper ring, and when, after cooling, the material shrinks slightly, the mortise-and-tenon linkages remain and ensure excellent retention of the cap.
Advantageously, the stripper ring includes three notches or three projections distributed on the periphery of an upstand on which, in the closed position of the mould, the lower edge of the skirt bears. In this way, the cap is held in place at three points, guaranteeing good stability without there being a risk of the cap jamming.
With the core of the mould includes three grooves in order to form three threads in the skirt of the cap, each notch or projection is placed between the ends, situated on the side of the stripper ring, of two adjacent grooves in the core. In this way, when extracting the core from the cap, the projections or notches produced on the cap are subjected to a minimal stress.
Likewise, each notch or projection is placed between two adjacent recesses in the mould, these being provided in order to produce the breakable linking elements which link the tamperproof ring to the skirt, so as to be able to demould the cap without there being a risk of damaging it.
The cap according to the invention is of the type having a cylindrical skirt, this skirt being provided with at least one screw thread and closed off at one end by a top, as well as a tamperproof ring linked to the free end of the skirt by breakable linking elements, the tamperproof ring including tabs which, bent up towards the inside of the cap and pointing towards the top of the cap, are intended to interact with an annular rib situated on the neck of a container intended to receive the cap.
According to the invention, this cap furthermore has, on the lower edge of the skirt and in at least two separate places, at least one projection and/or at least one notch.
Advantageously, the projections and/or notches are situated on zones corresponding to 30% of the circumference of the cap, at the utmost, and preferably to approximately 10% of the circumference of the cap. Moreover, the heighth of the projections or notches is less than or equal to 0.6 mm, and is, preferably, approximately 0.5 mm.
Indeed, the point is to give the projections or notches such dimensions as to ensure a good retention of the cap, without, however, the cap being caught too strongly on the stripper ring, which would be the case if the projections or notches were too big.
This amounts to a cap which can be manufactured in a mould such as defined hereinabove.
Preferably, the lower edge of the skirt includes three projections or three notches distributed on its periphery.
Advantageously, when the skirt includes three threads on its internal face, each projection or notch is placed between the ends, situated on the side of the free edge of the skirt, of two threads.
By analogy with the characteristics of the mould, each projection or notch is placed between two adjacent breakable linking elements.
REFERENCES:
patent: 3737064 (1973-06-01), Patel et al.
patent: 4529096 (1985-07-01), Chartier et al.
patent: 4697714 (1987-10-01), Towns et al.
patent: 5178888 (1993-01-01), Würl
patent: 5281385 (1994-01-01), Julian
patent: 5450973 (1995-09-01), Ellis et al.
patent: 5657889 (1997-08-01), Guglielmini
patent: 5803281 (1998-09-01), Towns
patent: 5913436 (1999-06-01), Breuer
patent: 5941403 (1999-08-01), Towns
patent: 37529 (1991-03-01), None
patent: 0 125 097 A2 (1984-11-01), None
patent: 2525565 (1983-10-01), None
patent: WO 94/18085 (1994-08-01), None
Benoît-gonin Claude
Champagnon Pascal
Astra Plastique, Societe Anonyme
Cronin Stephen K.
Oliff & Berridg,e PLC
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