OBJECT OF THE INVENTION
[0001] The present invention relates to a closure for cans, particularly for food cans,
specifically of the type in which the lid of the can is embodied as a frame that can
be attached to the can body or form part of it, determining a wide opening that is
closed by a detachable film.
[0002] The object of the invention is to achieve a maximum simplification of the means used
to attach the film to the frame and a perfect protection of these against the effects
over time on the content of the can and on its surrounding environment, all of this
with a complete absence of risk to the user when handling the can to open it.
BACKGROUND OF THE INVENTION
[0003] It is known that conventional food cans are constructed by a body made from a metal
plate suitable treated both externally and internally, said body adopting a prismatic,
cylindrical or other shape, which in any case and after it is filled receives on its
opening a closure lid that is also made of metal and has similar characteristics,
mechanically flanged on said opening to determine, in addition to a tight seal, a
peripheral flange used for its subsequent opening or as a support for a conventional
can opener.
[0004] In order to simplify opening the can for consumers, said conventional cans are increasingly
being replaced by those that incorporate a system referred to as "peel-off" in which
the lid is provided near the aforementioned peripheral flange with a punch-out determining
a weakened line that allows to peel off the lid, for which purpose the detachable
part of the lid is provided with a ring, which is first used to initiate the detachment
and then as a handle to continue peeling off the lid.
[0005] This solution allows to simplify greatly the opening of the can compared to the traditional
can opener, but it implies a considerable risk during the operation of opening the
can of cuts in the user's hands, so that the latest trend is toward the construction
of closures in which the lid is embodied as a peripheral frame attached, generally
by heat sealing, to a detachable film which, due to its nature, cannot harm the user.
[0006] The problem presented by this solution is that the inner, cut-out edge of the ring
configured by the aforementioned frame, as it is not covered in varnish, is liable
to rust in contact with the contents of the can, leading to a contamination of said
contents.
[0007] Some patents have attempted to solve this problem by flanging, curling or folding
the cut-out edge to avoid its contact with the contents of the can and prevent its
oxidation.
[0008] In this sense may be cited European Patent
EP 0 408 268 in which the inner cut-out edge of the ring determined by said frame is flanged outwards.
[0009] However, this solution has certain drawbacks. On one hand, the flange or curl of
the edge of the ring as foreseen in the aforementioned patent implies a risk to the
consumer after the container has been opened, as said edge is unprotected and may
result in cuts.
[0010] On another hand, said patent foresees the presence of a double sealing area of the
closure area of the container, so that both faces of the plate forming the frame or
the ring must have a plastic coating for heat sealing, which increases the cost of
the product greatly and worsens the mechanical properties regarding a simple opening
of the container. In addition, the two areas where heat sealing must be applied have
a different thickness, specifically double in one than the other, requiring to adapt
the process to the area of greater thickness therefore using a higher temperature
and increasing the duration of the process, endangering the microbial safety of the
product. On another hand, the effect of the heat sealing will in principle flatten
the curl and in the long term can produce a rebound effect, both of these factors
affecting the conditions of the two seals and therefore the sealing level of the container.
It must also be mentioned that double heat sealing does not only make it more difficult
to open the container but may also lead to breaking of the lid or spilling the preserving
liquid when the can is opened.
[0011] Another solution is disclosed in Spanish Patent
ES 2 029 432, in which the frame or ring is configured as a monobloc extension of the body of
the can and in which the edge is concealed by a disposition of the body of the can
in layers, made by folding the body inwards. However, this disposition of the can
body is difficult to carry out and implies a very complex clidping. In addition, the
proposed disposition in layers proposed by this patent requires a forced position
of the can which can also lead to a rebound effect due to the heat sealing that must
be applied in the area, separating the layers from one another and exposing the edge,
with the corresponding risk for the can user and risk of oxidation of the product
contained in the can.
[0012] On another hand, the solutions proposed hitherto do not allow to use different materials
in the body and in the lid or film, so that if the two materials are different when
the inner cut-out edge comes in contact with the detachable film a galvanic corrosion
will eventually take place that will cause a premature destruction of the closure
lid of the container.
[0013] Finally, on
NL 1013957 is described a closure for cans, but although discloses a flange being at a lower
height than the rest of the lip, it is not described any means for simplifying the
heat soldening process and the subsequent operation for detaching the film acting
as a lid.
DESCRIPTION OF THE INVENTION
[0014] The can closure proposed by the invention solves the aforementioned drawbacks in
a fully satisfactory manner as regards the various issues discussed.
[0015] To do so, based on a body with any configuration made of a metal plate, ending at
its opening with an inner peripheral lip to which a film is attached by heat sealing,
the invention relies on the fact that said lip has a marginal area, internal or external,
flanged or folded by mechanical means to determine a substantially cylindrical curl
or flange, so that the marginal area of said flange near its free end is mechanically
attached to the initial area of the flange, producing a mechanical closure by contact
of the two surfaces and thereby protecting the free and initially cutting edge of
the body.
[0016] The configuration of the curl proposed in the invention is such that the curl or
flange is at a lower height than the rest of the lip or on the outside of the can,
allowing the film to be attached by heat soldering to the tab in its flat greater
sector along a peripheral attachment line with a single attachment, which facilitates
the detachment of the film during the opening process without the need for an additional
heat sealing line inside said curl or flange.
[0017] On another hand, this mechanical protection of the inner edge of the container, and
its lack of contact with the film, prevent the galvanic corrosion effect related to
the use of different metals joined to one another, which allows using different materials
for the lid and the container, which until now was not possible.
[0018] According to another characteristic of the invention it is foreseen that the attachment
of the film that constitutes the lid is effected by heat soldering on the ring or
peripheral lip of the body in the flat, greater section of said lip without the inner
edge being affected by said union.
DESCRIPTION OF THE DRAWINGS
[0019] To complete the description being made and in order to aid a better understanding
of the characteristics of the invention, according to an example of a preferred embodiment,
a set of drawings is accompanied forming an integral part of said description where
for purposes of illustration and in a nonlimiting manner the following is represented:
Figure 1.- Shows a perspective view of a can provided with the closure that constitutes
the object of the present invention, according to a classic example of a practical
embodiment of said can in which it adopts a configuration tending towards a rectangular
prism.
Figure 2.- Shows an enlarged detail in cross-section of the can of the previous figure,
at its opening and according to a first embodiment of the invention.
Figure 3.- Shows a cross-section similar to that of the previous figure corresponding
to a second embodiment of the invention.
Figure4.- Shows a third embodiment in which the closure is placed between the external
fold and the content of the can.
Figure 5.- Shows a fourth embodiment in which the fold is concealed under the edge
of the can.
PREFERRED EMBODIMENT OF THE INVENTION
[0020] In view of said figures, it can be seen that the closure taught is applicable to
food cans obtained from a metal plate that has been suitably treated both internally
and externally to withstand external environmental effects and those derived from
its own content, a can which in the example of embodiment selected adopts a prismatic
configuration, as mentioned above, but which could also be cylindrical, with an elliptical
outline or with any other configuration. Said metal plate configures a body (1) that
is open on the top and ends at a peripheral frame (2) which is attached to the opening
of said body (1) by a conventional flanging method, as shown in figure 2, in which
frame is defined an internal peripheral lip (3), preferably included in an imaginary
horizontal plane, to which is attached by heat soldering, adhesive or any other suitable
means a film (4) that constitutes the lid as such and which can be obtained from a
conventional complex from a metal sheet internally coated with a plastic film.
[0021] However, as shown in figures 3, 4 and 5, the lid may lack said frame (2) as a physically
independent part of the body (1), so that the lip (3') will be obtained from the body
(1) of the can by curling its opening, as in the previous case attaching the aforementioned
film (4) to this lip (3').
[0022] In both cases the film (4) can also be provided with a tab (5) to be pulled by hand
which constitutes a grip used to open the can.
[0023] According to the invention and to protect the edge (6) defined when punching the
lip (3-3'), which obviously is not provided with the inner varnish coating of the
plate nor its outer coating, it is foreseen that said lip (3-3') incorporate in its
marginal area an inner flange or fold (7), substantially cylindrical, as shown in
any of figures 2, 3, 4 and 5. This said flange is obtained by mechanical means and
will be displaced towards the interior of the container as shown in figures 2 and
3 or towards its exterior, as shown in figures 4 and 5, so that the marginal area
(9) of said flange near its free end (6) is attached by a mechanical union to the
initial area of the flange.
[0024] This embodiment prevents the contact between the unprotected metal of the edge of
the body or the peripheral frame with the closure film, thereby preventing the galvanic
corrosion of the closure film and the premature destruction of the container and its
contents.
[0025] In the subsequent attachment by heat soldering of the film (4), said film is attached
exclusively to the flat area (8) of the lip (3-3'), as the flange is at a lower plane
than the lip, which simplifies greatly the heat soldering process and the subsequent
operation for detaching the film (4).
Figures 4 and 5 show corresponding embodiments in which the flange is placed in the
can outside the soldering area of the film, so that for example in figure 4 said flange
is raised and can even define a surface allowing a simple stacking of the containers,
the exposed flange not contacting the inside of the container in any manner.
Figure 5 shows another embodiment of the flange in which it is concealed in the bottom
part, forming a flat surface on which the closure film is sealed.
1. - Closure for cans, particularly food cans, in which participates a body (1) made
of metal plate that ends at its opening with a peripheral internal lip (3,3') comprising
a flat area (8) to which is attached by heat sealing a film (4) that acts as a lid,
where
said lip (3,3') has a substantially cylindrical flange (7) and where said flange (7)
is at a lower height than the rest of the lip (3,3'), and in that
the marginal area of said flange (7) near its free end is attached by a mechanical
union to the initial area of the flange (7) by mechanical means, characterised in that said film (4) is attached exclusively to the flat area (8) of the lip (3-3')
2. - Closure for cans, according to claim 1, characterised in that the marginal area of the flange (7) near its free end is on the inside of the container,
covered by the heat soldered film (4).
3. - Closure for cans, according to claim 1, characterised in that the marginal area of the flange (7) near its free end is on the outside of the container,
protected from the contents of the inside of the container.
4. - Closure for cans, according to the previous claims, characterised in that the lip (3) is embodied as a piece that is physically independent of the container
body (1) which is attached to the opening of the latter by the conventional curling.
5. - Closure for cans, according to previous claims, characterised in that the peripheral lip (3') forms a single body with the can body (1).
6. - Closure for cans, according to claims 1 to 5, characterised in that the film (4) that serves as a lid has an extension by way of a handle (5).
1. Verschluss für Dosen, insbesondere Lebensmitteldosen, zu dem ein Körper (1) gehört,
der aus Blech besteht und an seiner Öffnung mit einer Umfangs-Innenlippe (3, 3') endet,
die einen flachen Bereich (8) umfasst, an dem mittels Heißkleben ein Film (4) angebracht
wird, der als ein Deckel wirkt, wobei die Lippe (3, 3') einen im Wesentlichen zylindrischen
Flansch (7) aufweist, der Flansch (7) eine geringere Höhe hat als der Rest der Lippe
(3, 3') und der Randbereich des Flansches (7) in der Nähe seines freien Endes durch
eine mechanische Verbindung mit mechanischen Mitteln an dem Anfangsbereich des Flansches
(7) angebracht wird, dadurch gekennzeichnet, dass der Film (4) ausschließlich an dem flachen Bereich (8) der Lippe (3, 3') angebracht
ist.
2. Verschluss für Dosen nach Anspruch 1, dadurch gekennzeichnet, dass der Randbereich des Flansches (7) in der Nähe seines freien Endes an der Innenseite
des Behälters liegt und mit dem heißgeklebten Film (4) abgedeckt ist.
3. Verschluss für Dosen nach Anspruch 1, dadurch gekennzeichnet, dass der Randbereich des Flansches (7) in der Nähe seines freien Endes an der Außenseite
des Behälters liegt und gegenüber dem Inhalt im Inneren des Behälters geschützt ist.
4. Verschluss für Dosen nach den vorangehenden Ansprüchen, dadurch gekennzeichnet, dass die Lippe (3) als ein Teil ausgeführt ist, das physisch unabhängig von dem Behälterkörper
(1) ist und an der Öffnung des Letzteren durch herkömmliches Bördeln angebracht wird.
5. Verschluss für Dosen nach den vorangehenden Ansprüchen, dadurch gekennzeichnet, dass die Umfangslippe (3') einen durchgehenden Körper mit dem Dosenkörper (1) bildet.
6. Verschluss für Dosen nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass der Film (4), der als ein Deckel dient, eine Verlängerung in Form eines Griffteils
(5) aufweist.
1. Fermeture pour des boîtes de conserves en particulier des boîtes de conserves alimentaires
comprenant un corps (1) formé à partir d'une plaque métallique se terminant par une
ouverture munie d'une lèvre périphérique interne (3, 3') ayant une zone plate (8)
à laquelle est fixé un film (4) par thermosoudage, le film constituant un couvercle,
- la lèvre (3, 3') ayant une bride (7) essentiellement cylindrique,
- la bride (7) se trouvant en dessous du restant de la lèvre (3, 3'),
- la zone marginale de la bride (7) près de son extrémité libre, est fixée par un
assemblage mécanique à la zone initiale de la bride (7), par l'intermédiaire d'un
moyen mécanique, fermeture caractérisée en ce que
le film (4) est fixé exclusivement à la zone plate (8) de la lèvre (3, 3').
2. Fermeture de boîtes de conserves selon la revendication 1, caractérisée en ce que
la zone marginale de la bride (7) à proximité de son extrémité libre, se trouve sur
le côté intérieur du conteneur couvert par le film (4) thermosoudé.
3. Fermeture de boîtes de conserves selon la revendication 1, caractérisée en ce que
la zone marginale de la bride (7) à proximité de son extrémité libre, se trouve sur
le côté extérieur du conteneur, en étant protégée du contenu à l'intérieur du conteneur.
4. Fermeture de boîtes de conserves selon l'une des revendications précédentes,
caractérisée en ce que
la lèvre (3) est réalisée sous la forme d'une pièce physiquement indépendante du corps
(1) du conteneur et fixée à l'ouverture de celui-ci par un sertissage.
5. Fermeture de boîtes de conserves selon l'une des revendications précédentes,
caractérisée en ce que
la lèvre périphérique (3') est réalisée en une seule pièce avec le corps de la boîte
de conserves (1).
6. Fermeture de boîtes de conserves selon l'une des revendications 1 à 5,
caractérisée en ce que
le film (4) qui sert de couvercle, a un prolongement par une poignée (5).