FIELD OF THE INVENTION

The present invention concerns a closing/opening device for a container adapted to contain pourable products. In particular, such closing/opening device is adapted for the use of particularly viscous liquids, such as olive oil, or can be combined with containers of reduced sizes (for example of a volume of less than 0.5 liters), in this case also containing food products such as, for example, fruit juice or milk, whose pouring flow must however be lower than that achieved in larger containers (for example 1 liter). It is clear that such opening/closing device can however also be used in larger containers of more than 0.5 liters.

KNOWN PRIOR ART

According to the known art, there are closing/opening devices for pouring pourable products. For example, the patent WO9505996 in the name of International Paper Company Inc. describes a closing device with three components, i.e. comprising a collar-shaped based having a flange combinable at a perforable portion of the container, a cutting element adapted to perforate the perforable portion of the container at the first opening of the device and adapted at least to slide, or to be screwed, inside said collar, and an upper cap that screws on the collar and whose task is to both control the displacement of the cutting element at the first opening of the device and to preserve the pourable product inside the container until the container, although open, still hasn't been completely emptied of its content.

A similar opening/closing device is described in the patent EP 1088764 in the name of Tetra Laval Holding & Finance SA.

If positioned on the upper surface of a container, such devices allow a rather copious pouring of the pourable product present inside the container. However, in case of small-sized containers, the size of these opening/closing devices is excessive, thus implying a pouring flow unnecessary for the end user. Moreover, it is also difficult to position them on the upper region of the container, where the perforable portion is obtained, due to the presence of at least one creasing of the container. Also when decreasing the diameter of the collar and of the cap of such opening/closing devices, the flow of liquid coming out of the mouth of the collar would anyhow continue to be excessive with respect to the requirements of the user. Also, there would be serious problems with such small-sized opening/closing devices, due to the difficulty in opening the container, as well as in their molding. In particular, if of excessively reduced sizes, the cutting element would no longer be able to effectively break the perforable portion of the container.

For the reasons mentioned above, it is clear that the opening/closing devices of the known art would not be appropriate to be used also on the multilayered containers used for containing a pourable food product having viscosity greater than that of the products usually contained in the multilayered containers mentioned above, such as, for example, fruit juices, milk and other similar product. A high viscosity product can for example be olive oil or similar products.

Object of the present invention is thus to make an opening/closing device that can also be combined with containers whose upper surface having the perforable portion is of reduced sizes.

A further object of the present invention is to make an opening/closing device that allows a reduced and, however, controlled pouring of the pourable product contained inside the container.

Still another object of the present invention is to make an opening/closing device that can also be used on multilayered containers containing pourable high viscosity products such as, for example, olive oil and the like.

Moreover, object of the present invention is to implement a method for opening/closing a multilayered container for pourable products of reduced sizes and/or containing high viscosity fluids.

Finally, object of the present invention is to implement a method for making an opening/closing device that solves the problems of the devices of the known art mentioned above.

These and other objects are achieved by an opening/closing device for a container for pourable products having at least one perforable portion, said opening/closing device comprising a base combinable with said container at said perforable portion, at least one cutting element provided with a sharp end arranged on the lower side of said cutting element, and at least one first passage obtained in said base, said at least one cutting element being constrained at least translatably to said base inside said first passage between a first position, in which said cutting element is combined separably with said base, and a second position, in which said cutting element has reached and perforated said perforable portion, characterized in that said base comprises at least one second passage for pouring said pourable product contained in said container, wherein said first passage and said second passage are obtained at a region of said base spaced from the upper surface of said perforable portion, at least when said base is combined with said container, so that to define a cavity between the lower surface of said region and the upper surface of said perforable portion, said cutting element being shaped so that to impede, at least when it has reached said second position, the passage of said pourable product through said first passage and to allow the outflow of said pourable product from said container to said at least second passage through said cavity.

Such solution thus allows to solve the problems of the containers of the known art. In fact, the outflow of the liquid contained inside the container occurs through a second passage, different from the one through which the perforable portion is perforated. For such reason, it is possible to appropriately calibrate the sizes of the second passage so that to limit the flow of pourable product through such second passage. Also, in case of a particularly viscous pourable product, the outflow of the product would be easily controlled, in the same way as it occurs when using a cruet or similar product, wherein the pouring spout is sized to avoid excessive flow rates.

According to the invention, said cutting element is provided with a third passage shaped so that, at least when said cutting element has reached said second position, said third passage allows the fluidic communication between said second passage and the inside of said container through said cavity.

In particular, said cutting element is provided with a hollow tubular side surface having a base surface closed at the top, opposite the lower side provided with said at least one sharp end, said third passage being obtained on said tubular surface of said hollow cutting element.

Preferably, said base is substantially plate-shaped and surrounds, with its outer perimeter, the perforable portion of the container. The portion of the base into contact with the container is also known under the name flange.

The base comprises a first collar provided with said first passage and adapted to guide the displacement of said cutting element between said first position and said second position. The base further comprises a second collar provided with said second passage for pouring said pourable product.

Always according to the invention, the opening/closing device comprises a cap for the removable covering of at least said second passage; said cap being made in one piece with said base and being constrained integrally with said base by a plastic hinge. In practice, by rotating the cap, around the hinge, with respect to the base, it is possible to open and close the container.

Preferably, said cap comprises means for combining/separating said cap with/from said second collar of said base so that to close/open said second passage.

According to a first embodiment of the invention, said cutting element is made in one piece with said cap and is separably connected with said cap by a plurality of frangible bridges arranged at said upper base surface of said cutting element; said frangible bridges are broken at least when said cap is separated for the first time from said second collar.

According to a second embodiment of the invention, said cutting element is made in one piece with said cap and is separably connected to said cap by a plurality of frangible bridges arranged at said upper base surface of said cutting element; said frangible bridges are broken at least when said cutting element is displaced for the first time from said first position to said second position. In this embodiment, the displacement of the cutting element from the first to the second position occurs when the cap is still combined with the base.

According to a further embodiment of the invention, said cutting element is made in one piece with said first collar and is separable from said first collar by means of a plurality of frangible bridges. Said frangible bridges are broken at least when said cutting element is displaced for the first time from said first position to said second position. The displacement force is always exerted by the user, also in the case of the embodiments described previously. Moreover, the opening/closing device comprises locking means to lock said cutting element to said first collar in said first position and in said second position; said locking means being shaped to allow the translation of said cutting element only in direction of said perforable portion.

Still, said locking means comprise at least two hooking holes and at least one protrusion that is combinable with said hooking holes; said hooking holes being integral with said cutting element and said protrusion being integral with the inner surface of said first collar. Advantageously, said two hooking holes are spaced from one another longitudinally with respect to said cutting element so that, when they are combined with said protrusion, said cutting element is at said first position and said second position.

As an alternative, said locking means comprise at least one hooking hole and at least two protrusions combinable with said hooking hole, wherein said hooking hole, in the specific case of blind type, is integral with the inner surface of said collar and said protrusions are integral with said cutting element.

The objects mentioned above are also achieved by means of a method for opening/closing a container for pourable products, which is provided with an opening/closing device according to one or more of claims 1 to 13, comprising the steps of:

a) causing at least the translation of said cutting element inside said first passage from said first position to said second position;

b) causing, at least when said cutting element reaches said second position, the breaking of said perforable portion;

characterized by comprising, successively to said step b), the step of c) pouring said pourable product outside of said container through said second passage, wherein said first passage and said second passage are obtained at a region of said base spaced from the upper surface of said perforable portion, at least when said base is combined with said container, so that to define a cavity between the lower surface of said region and the upper surface of said perforable portion, said cutting element being shaped so that to impede, at least when it has reached said second position during said step a), the passage of said pourable product through said first passage and to allow the outflow of said pourable product from said container to said at least second passage through said cavity during said step c) of the method.

In particular, the method comprises, before said step a), the step of d) removably combining said cap with said second collar of said base for the removable covering of said at least one second passage.

According to a first embodiment of the invention, wherein said cutting element is made in one piece with said cap and is separably connected with said cap by a plurality of frangible bridges arranged at said upper base surface of said cutting element, the method is characterized by comprising the step of e) causing the breaking of said frangible bridges at least when said cap is separated for the first time from said second collar.

According to a second embodiment of the invention, wherein said cutting element is made in one piece with said cap and is separably connected with said cap by a plurality of frangible bridges arranged at said upper base surface of said cutting element, the method is characterized by comprising the step of e') causing the breaking of said frangible bridges by means of said step a) of the method at least when said cap still has not been separated for the first time from said second collar.

According to a third embodiment of the invention, wherein said cutting element is made in one piece with said first collar and is separable from said first collar by a plurality of frangible bridges, said method is characterized by comprising the step of e") causing the breaking of said frangible bridges at least when said cutting element is displaced for the first time from said first position to said second position during said step a) of the method.

The objects are also achieved by means of a method for molding an opening/closing device according to one or more of claims 1 to 13, wherein said cutting elements, said base and said cap are molded in one piece, wherein said cap is constrained integrally to said base by a plastic hinge. This allows to considerably simplify the production of the opening/closing devices of the known art since a single mold allows to obtain the entire device.

According to a first embodiment of the invention, wherein said cutting element is made in one piece with said cap and is separably connected with said cap by a plurality of frangible bridges, the molding method is preferably characterized in that said frangible bridges are sized to be broken at least when said cap is separated for the first time from said second collar.

According to a second embodiment of the invention, wherein said cutting element is made in one piece with said cap and is separably connected with said cap by a plurality of frangible bridges, the molding method is preferably characterized in that said frangible bridges are sized to be broken at least when said cutting element is displaced for the first time from said first position to said second position.

According to a third embodiment of the invention, wherein said cutting element is made in one piece with said first collar and is separable from said first collar by a plurality of frangible bridges, said molding method is characterized in that said frangible bridges are sized to be broken at least when said cutting element is displaced for the first time from said first position to said second position.

The objects are also achieved by means of a method for molding an opening/closing device according to one or more of claims 1 to 13, wherein only said base and said cap are molded in one piece, wherein said cap is constrained integrally to said base by a plastic hinge.

In this case, the cutting element is molded separately and is combined with the first collar during the mounting steps of the opening/closing device.

Some particular embodiments of the present invention will now be described by way of example only and without limitations with respect to the accompanying figures, in which:

figure la is a perspective view of the opening/closing device according to the invention, still closed and mounted on a generic container for pourable products; figure lb is a sectional longitudinal view of the opening/closing device of figure la;

figure lc is a sectional longitudinal view of the opening/closing device of figure la when the cap is separated from the base for the first time;

figure Id is a sectional longitudinal view of the opening/closing device of figure la when the cutting element has reached its second position;

figure le is a sectional longitudinal view of the opening/closing device of figure la when the cap is combined with the base again;

figure 1 f is a perspective view of the opening/closing device according to figure le;

figure lg is a sectional longitudinal view of the device of figure la just obtained by molding;

figure lh is a perspective view of the opening/closing device of figure lg; figure 2a is a perspective view of the opening/closing device according to a second embodiment of the invention, still closed and mounted on a container for pourable products;

figure 2b is a sectional longitudinal view of the opening/closing device of figure 2a;

figure 2c is a perspective view of the opening/closing device of figure 2a after the cutting element has reached the second position, before the opening of the cap; figure 2d is a sectional longitudinal view of the opening/closing device of figure 2c;

figure 2e is a sectional longitudinal view of the opening/closing device of figure 2a when the cap is separated from the base;

figure 2f is a sectional longitudinal view of the opening/closing device just molded;

figure 2g is a perspective view of the device of figure 2f;

figure 3a is a perspective view of the opening/closing device according to a second embodiment of the invention, still closed and mounted on a container for pourable products;

figure 3b is a sectional longitudinal view of the opening/closing device of figure 3 a;

figure 3c is a perspective view of the opening/closing device of figure 3a after the cap was opened for the first time;

figure 3d is a sectional longitudinal view of the opening/closing device of figure 3 c;

figure 3e is a sectional longitudinal view of the opening/closing device of figure 3a when the cutting element reaches the second position; figure 3f is a sectional longitudinal view of the opening/closing device of figure 3a when the cap is combined with the base again;

figure 3g is a sectional longitudinal view of the opening/closing device just molded.

With particular reference to such figures, 1 denotes the general opening/closing device according to the invention.

The opening/closing device 1 is applied on a container 100 (not completely shown herein, but known to the expert of the sector) for pourable products having a perforable portion 101. Such container 100 is made in a known way by means of a laminated material obtained by overlapping with one another various layers of paper, cardboard, polyethylene and/or other additional materials, appropriately shaped and folded, generally parallelepiped-shaped, and having a perforable portion 101, i.e. a portion of the laminated material devoid of the paper, or cardboard, layer at their end, and thus easily perforable by a cutting body to thus allow the outflow of the liquid contained in the container 100.

According to the embodiment herein described in figures la to lh, the opening/closing device 1 comprises a base 2, preferably plate-shaped, combinable with the container 100 at the perforable portion 101, a cutting element 5 provided with a sharp end 6 arranged on the lower side 5a of the cutting element 5, and a first passage 7 obtained in the base 2. The cutting element 5 is translatably constrained to the base 2 inside the first passage 7 between a first position PI (see figure lc), in which the cutting element 5 is separably combined with the base 2, and a second position P2 (see figure Id), in which the cutting element 5 has reached and perforated the perforable portion 101.

It should be noted that in other embodiments not shown herein, the displacement of the cutting element 5 with respect to the base 2 can also be of the rotary-translatory type, whenever, for example, the cutting element 5 is screwed inside the first passage 7, without however departing from the protection scope of the present invention. Advantageously, according to the invention, the base 2 comprises a second passage 8 for pouring the pourable product contained in the container 100. Moreover, the first passage 7 and the second passage 8 are made at a region 9 of the base 2 spaced from the upper surface 101a of the perforable portion 101 of the container 100, at least when the base 2 is combined with the container 100, so that to define a cavity 10 between the lower surface 9a of the region 9 and the upper surface 101a of the perforable portion 101. The cutting element 5 is also shaped so that, at least when it has reached the second position P2, to impede the passage of the pourable product through the first passage 7 and to allow the outflow of the pourable product from the container 100 to the second passage 8 through the cavity 10 (see the arrows shown in figure Id).

Moreover, the cutting element 5 is provided with a third passage 11 shaped so that, at least when the cutting element 5 has reached the second position P2, the third passage 11 allows the fluidic communication between the second passage 8 and the inside of the container 100 through the cavity 10.

As better shown in detail in figures Id and lh, the cutting element 5 is provided with a hollow tubular side surface 5b having a base surface 5c closed at the top and arranged on the opposite side with respect to the side 5a on which the sharp end 6 is located. The third passage 11 is made on the hollow tubular surface 5b of the cutting element 5. Thus, in practice, such third passage 11 fluidically connects the cavity 10 with the inner hollow part of the cutting element 5 which is in turn fluidically connected with the inside of the container 100. The second passage 8 is in turn fluidically connected with the cavity 10. Thus, when the perforable portion 101 is broken by the cutting element 5, since the pourable product cannot flow inside the first passage 7 inside which the cutting element 5 is arranged, after it has reached its second position P2, it can only cross the second passage 8. It should be noted that the sizes of the cutting element 5 are designed to ensure the seal of the first passage 7 and to thus prevent the flow of the pourable product from crossing it.

According to an embodiment described herein, the base 2 comprises a first collar 15 provided with the first passage 7 and adapted to guide the displacement of the cutting element 5 between the first position PI and the second position P2.

Moreover, the base 2 comprises a second collar 16 provided with a second passage 8 for pouring the pourable product.

According to an embodiment shown herein, the device 1 comprises a cap 20 for the removable covering of the second passage 8. Such cap 20 is advantageously made in one piece with the base 2 and is integrally constrained to the base 20 itself by a plastic hinge 90.

Moreover, the cap 20 comprises means 21 for combining/separating the cap 20 with/from the second collar 16 of the base 2 so that to close/open the second passage 8. Such means 21 comprise a collar 21 made in one piece with the cap 20 and adapted to be Interferingly combined with the second collar 16 and to thus allow the closing of the second passage 8.

According to a first embodiment of the invention shown in figures la to lh, the cutting element 5 is made in one piece with the cap 20 and is separably connected with the cap 20 by a plurality of frangible bridges 30 arranged at the upper base surface 5c of the cutting element 5. In particular, when still connected with the cap 20, such upper base surface 5c forms a portion thereof, thus the upper surface 20a of the cap 20 also comprises the upper base surface 5b of the cutting element 5. In particular, the frangible bridges 30 are broken when the cap 20 is separated for the first time from the second collar 16. In this variant of the invention, the cutting element 5, at the opening ofthe cap 20, i.e. when it is separated for the first time from the second collar 16, stays connected with the first collar 15, in its first position PI . The upper surface 20a of the cap 20 will thus stay devoid of an area exactly equal to the one occupied by the upper base surface 5c of the cutting element 5 (see figure If).

According to a second embodiment of the invention shown in figures 2a to 2g, like in the previous embodiment, the cutting element 5 is made in one piece with the cap 20 and is separably connected with the cap 20 by a plurality of frangible bridges 30' arranged at the upper base surface 5c of the cutting element 5. Unlike the previous embodiment, the frangible bridges 30' are sized to be broken only when the cutting element 5 is displaced for the first time from its first position PI to the second position P2. This occurs without having to separate the cap 20 from the second collar 16. In this embodiment, the upper base surface 5c of the cutting element 5 extends beyond the sizes of the perimeter of the hollow side surface 5b to allow the user to have a greater pushing surface for displacing the cutting element 5 from its first position PI to its second position P2.

According to a third embodiment of the invention shown in figures 3a to 3g, the cutting element 5 is made in one piece with the first collar 15 and is separable from the first collar by a plurality of frangible bridges 30". The frangible bridges 30" are sized to be broken at least when the cutting element 5 is displaced for the first time from the first position PI, obtained by means of the aforesaid frangible bridges 30", to said second position P2. In such an embodiment, the cap 20 fully covers the base 2 and must thus be rotated on the base 2 around the hinge 90 in order to be able to uncover the first collar 15 and the second collar 16 and to then allow the successive separation of the cutting element 5 from the first collar 15.

The opening/closing device 1 further comprises locking means 50 to lock the cutting element 5 to the first collar 15 in the first position PI and in the second position P2. Such locking means 50 are shaped to allow the translation of the cutting element 5 only in direction of the perforable portion 101, when the cutting element 5 is subjected to the pushing force exerted by the user on the upper base surface 5c of the cutting element 5.

Preferably, said locking means 50 comprise two hooking holes 51, 52 and a protrusion 53 combinable with the two hooking holes 51, 52. Such hooking holes 51, 52 are integral with the cutting element 5 and are obtained on its hollow tubular surface 5b, while the protrusion 53 is integral with the inner surface 15a of the first collar 15. One of the two holes, in particular the hole 51 located at a lower position (with the cutting element 5 inserted inside the first collar 15), also acts as a third passage 11. In fact, such hole 51 has longitudinal sizes, i.e. measured along the longitudinal axis of the cutting element 5, much greater than those of the other hole 52 since, in addition to performing the locking function of the cutting element 5 when it is in the first position PI and to impeding the translation of the cutting element 5 in the direction opposite the one in which the perforable portion 101 is located, it must also ensure the passage of a certain quantity of pourable product from the cutting element 5 to the cavity 10 when the cutting element 5 is in its second position P2. As a result of that which is mentioned above, the hole 51 must be facing the cavity 10 when the cutting element 5 is in its second position P2. The flow of the pourable product contained in the container 100 will thus cross the hollow part of the cutting element 5, will then pass through the third passage 11 (orthogonally to the lying plane of the section shown in figures Id, 2e and 3e), curving its direction by 90°, to then flow inside the cavity 10 (substantially disc-shaped) and subsequently pass inside the second passage 8.

The two holes 51, 52 are arranged longitudinally staggered with respect to the cutting element 5, i.e. at different heights considered in direction of the longitudinal axis T of the cutting element 5, and are located at the first position PI and second position P2 for the cutting element 5. The shape of the protrusion 53 is so that to not allow the cutting element 5 to be able to translate in the opposite direction, i.e. in the sense of coming out of the first collar 15, once it has exceeded the protrusion 53 and is slightly elastically deformed due just to the radial extension of the protrusion 53. In other embodiments, the two holes 51, 52 are in couples of two and arranged on diametrically opposite portions of the hollow tubular surface 5b, and the protrusions 53 are two in number, also arranged in diametrically opposite positions of the inner surface 15a of the first collar 15. The protrusion 53 has a ramp on its upper surface to facilitate the two holes 51, 52 to enter.

In other embodiments not shown herein, the locking means 50 comprise a single hooking hole and two protrusions combinable with the hooking hole. Such hooking hole is integral with the first collar and is obtained on the inner surface of the first collar, and the protrusions are integral with the outer surface of the cutting element and are arranged longitudinally with respect to the first collar, i.e. at different heights considered in the direction of the longitudinal axis of the cutting element, and at the first position and second position for the cutting element.

Always according to the invention, a method for closing/opening a container 100 for pourable products, provided with an opening/closing device 1 according to the description specified above, in particular according to one or more of claims 1 to 13, is described here below. Such method comprises the steps of:

a) causing the translation of the cutting element 5 inside the first passage 7 from the first position PI to the second position P2;

b) causing, at least when the cutting element 5 reaches the second position P2, the breaking of the perforable portion 101;

moreover, successively to said step b), the method comprises the step of c) pouring the pourable product outside of the container 100 through the second passage 8, wherein the first passage 7 and the second passage 8 are obtained at a region 9 of the base 2 spaced from the upper surface 101a of the perforable portion 101 when the base 2 is combined with the container 100, for example by gluing, so that to define a cavity 10 between the lower surface 9a of the region 9 of the base 2 and the upper surface 101a of the perforable portion 101; the cutting element is further shaped so that to impede, when it has reached the second position P2 during the step a), the passage of the pourable product through the first passage 7 and to allow the outflow of the pourable product from the container 100 to the second passage 8 through the cavity 10 during the step c) of the method.

Always according to the invention, the method comprises, before the step a), the step of d) removably combining the cap 20 with the second collar 16 of the base 2 for the removable covering of the second passage 8.

According to a first embodiment of the invention shown in figures la to lh, wherein the cutting element 5 is made in one piece with the cap 20 and is separably connected with the cap 20 by a plurality of frangible bridges 30 arranged at the upper base surface 5c of the cutting element 5, the method also comprises the step of e) causing the breaking of such frangible bridges 30 when the cap 20 is separated for the first time from the second collar 16. Advantageously, the step d) comprises the further step of dl) removably locking the cutting element 5 to the first collar 15 in its first position PI the first time that said cap 20 is combined with the base 2 and so that to allow at least the translation of the cutting element 5 only in direction of the perforable portion 101. In practice, when the cap 20 is combined with the second collar 15 for the first time after the molding, the hooking hole 51 obtained in the cutting element 5 is combined with the protrusion 53. Consequently, since at that point it is impossible for the cutting element 5 to come out of the first collar 15, just due to the shape of the protrusion 53, the frangible bridges 30 break when the user rotates the cap 20 for the first time with respect to the base 2, thus leaving the cutting element 5 in its first position PI .

According to a second embodiment of the invention, shown in figures 2a to 2g, wherein the cutting element 5 is made in one piece with the cap 20 and is separably connected with the cap 20 by a plurality of frangible bridges 30' arranged at the upper base surface 5c of the cutting element 5, the method also comprises the step of e') causing the breaking of such frangible bridges 30' by means of said step a) of the method when the cap 20 still has not been separated from the second collar 16. Advantageously, the step d) comprises the further step of dl') removably locking the cutting element 5 to the first collar 15 in its first position PI the first time that said cap 20 is combined with the base 2 and so that to allow at least the translation of the cutting element 5 only in direction of the perforable portion 101.

According to a third embodiment of the invention (see figures 3a to 3g), wherein the cutting element 5 is made in one piece with the first collar 15 and is separable from the first collar 15 by a plurality of frangible bridges 30", the method comprises the step of e") causing the breaking of the frangible bridges 30" at least when the cutting element 5 is displaced for the first time from the first position PI to the second position P2 during the step a) of the method.

Finally, a method for making an opening/closing device 1 according to one or more of claims 1 to 13, wherein the cutting element 5, the base 2 and the cap 20 are molded in one piece, wherein the cap 20 is integrally constrained to the base 2 by a plastic hinge 90 (see figures lg, lh, 2f, 2g and 3g), is described here below.

It should be noted that the molding is obtained in a mold in which the cap 20 is arranged rotated by 180 ^° with respect to the base 2, thus allowing to prevent the presence of undercuts in the mold.

According to the invention, according to a first embodiment of the invention, wherein the cutting element 5 is made in one piece with the cap 20 and is separably connected with the cap 20 by a plurality of frangible bridges 30, the method consists in that the frangible bridges 30 are sized to be broken when the cap is separated for the first time from the second collar 16.

Always according to the invention, according to a second embodiment of the invention, wherein the cutting element 5 is made in one piece with the cap 20 and is separably connected with the cap 20 by a plurality of frangible bridges 30', the method consists in that the frangible bridges 30' are sized to be broken at least when the cutting element 5 is displaced for the first time from the first position PI to the second position P2.

Finally, according to a third embodiment of the invention, wherein the cutting element 5 is made in one piece with the first collar 15 and is separable from the first collar 15 by a plurality of frangible bridges 30", the method consists in that the frangible bridges 30" are sized to be broken at least when the cutting element 5 is displaced for the first time from the first position PI to the second position P2.

It should be noted that in other embodiments not shown herein, the opening/closing device 1 is made so that the base 2 and the cap 20 are molded in one piece, wherein the cap 20 is integrally constrained to the base 2 by a plastic hinge 90. In this case, the cutting element 5 is molded separately and is combined with the first collar 15 during the mounting steps of the opening/closing device 1.