ES2368533T3 - PLASTIC CLOSURE DEVICE WITH CUTTING CAP. - Google Patents

Abstract

Plastic closing device, with a pouring mouth (1) for fixing on a container, with a screw cap (2) that can be screwed on the pouring mouth (1), and with an automatic opening bushing (3) that to open the container, it can be moved inside the mouth d5 and poured (1) helically down towards the container, the screw cap (2) presenting at least one drag (24) acting on at least a stop element (36) of the automatic opening bushing (3) and causing the automatic opening bushing (3) to move through the inside of the pouring mouth (1) for the first time ) towards a lower position towards the container in order to open it, and that during the subsequent closing of the spout (1) by means of the screw cap (2) the automatic opening bushing (3) remains in its lower position, and presenting the automatic opening bushing (3) at least two elements cutting and / or drilling points (32a-32e) that protrude downwards, which are arranged on the perimeter of the automatic opening bushing (3) and that form a lower edge thereof, presenting the cutting and / or drilling elements ( 32a-32e) an essentially rectangular shape, in which a longitudinal edge protruding downward interrupts the rectangular shape, forming a triangle protruding downward, so that a point protruding downward is formed, the longitudinal edge presenting an area that in relation to the direction of rotation of the bushing (3), it has in front a zone that descends downwards and then an ascending zone, characterized in that the ascending zone is longer and is flatter than the descending zone.

Description

Plastic closure device with cutting bush

Technical aspect

The invention relates to a plastic closure device with a cutting bush according to the preamble of claim 1. The closure device is especially suitable for sealed containers containing a fluid content, preferably a beverage.

State of the art

A generic closure device is known from EP 1 088 764. This device is composed of three parts, which are a screw cap, a bottom part and a cutting bush. The lower part is made with a tubular shape and has a peripheral flange on its underside through which it can be fixed on a beverage container. The tubular shaped part forms a pouring spout that can be closed by the screw cap. The cutting bush is also made with a tubular shape and has a cutting tooth at its lower end. When the package is still unopened, the cutting sleeve is inside the bottom, and the screw cap is threaded on the bottom. If the screw plug is now rotated to open the closing device then, thanks to a drag system, the cutting bushing also rotates, while moving in the axial direction downwards. In this way, the container and in particular the sheet of the package are cut circularly along a controlled breakage line. After a predetermined angle of rotation, that is when the container has been opened sufficiently, the drag coupling between the screw cap and the cutting sleeve is released. Now the screw cap can be completely removed from the pouring spout and can be repositioned over it to close it, without moving the cutting bush that has penetrated into the container again. The cutting bush and the lower part are molded into a single piece in a previous assembly in which they are secured to each other coaxially by means of radial connecting bridges. These bridges extend between the upper edge of the cutting bush and the lower side of the lower part. These bridges break when the cutting bush first penetrates into the bottom.

Theoretically there are no limits as to the shape and design of this kind of closures. However, in practice they should be able to be manufactured using an injected casting process. In addition to this they should be able to be manufactured in the most economical way possible.

Various kinds of packages are known that can be opened with this kind of automatic opening closures. Among the known packages there are in particular composite containers comprising a layer of paper or cardboard that is laminated with one or several thin layers of plastic and / or metal. A typical composite container comprises, for example, a layer of cardboard which, inside the package, is provided with a thin layer of aluminum, which in turn is provided with a layer of polyethylene (PE). Lately, containers that no longer have any layer of cardboard are being imposed more and more, but are formed of a relatively thick plastic sheet, in particular exclusive PE containers, which in any case are equipped with one or more barrier layers. thin

During the manufacture of the container, a weakening of the container is normally carried out in the area where the closure is then to be placed, for example a pre-punched to allow the cutting bush to more easily pass through the wall of the container. For this and depending on the structure of the container and the manufacturing process there are several possibilities. In a container exclusively of PE, for example, a weakening line of circular shape can be formed in the wall having a smaller wall thickness. In a composite container, a weakened area is generally formed in which the cardboard layer is crossed entirely if possible in a circularly shaped area (for example by pre-punching). When this pre-punching is done before the cardboard is coated with the other layers, the circular disc cut out of the cardboard is generally removed before coating with the other layers. A container is therefore formed that in the area of the future hole has a circular shaped area consisting only of the thin layers of aluminum foil and / or plastic, but where there is no cardboard. On the other hand, if the cardboard layer is only perforated after the coating has been made, the cut circular disc will be joined with the layers of the sheet.

For each of these containers of different structure, a different kind of automatic opening bushing is generally used. Thus, for example, in a composite container that has a circular area in the area of the hole that consists solely of sheet layers, it is not convenient if the automatic opening sleeve exerts a large axial force on the sheet layers (" push"). In this case there is a tendency for the layers of sheet to give in to this force, bulging into the container. Therefore a container of this class should be opened as far as possible by cutting. Conversely, in those packages in which the carton is still present, it is advantageous if a pressure force is mainly exerted.

Known automatic opening closures also require a very precise positioning of the closure over the intended opening area and prepared by means of a weakening. If in this kind of closures the positioning is not exactly centered, a clean opening of the container is often not ensured.

From WO 03/002419 a closure is known with an automatic opening bushing which has two cutting elements that are arranged consecutively and have a triangular basic shape.

Also WO 2006/089440 shows an automatic opening bushing with two triangular cutting teeth.

In WO 2004/083055 triangular cutting teeth are also disclosed. In this case there is also a piercing tooth. If a sheet of the laminated packaging material has not been cut cleanly by the cutting teeth, it is perforated by the piercing tooth.

WO 2007/030965 discloses an automatic opening bushing having three teeth. Each of these teeth has a basic triangular shape, which is continued with a reinforcement flange. In two of the teeth, this flange is then disposed of the tooth in the direction of rotation, while in the third tooth it is formed prior to this.

Each of these automatic opening bushings is optimized for a particular class of packaging. Therefore none of the automatic opening closures provide a satisfactory result for all kinds of containers mentioned above, but will fail at least in one class of packages.

Exhibition of the invention

It is therefore one of the objectives of the invention to create a closure device of the class mentioned above, which can be manufactured at an economical cost. Another object of the invention is to describe a closure device that is suitable for effectively punching various kinds of packages of different structure or different preparation. Another object of the invention is to describe a closure device that successfully opens different kinds of packages, even if it is not perfectly centered on a weakened area of the package.

This objective is solved by a closing device that has the characteristics of claim 1.

The plastic closure device according to the invention has a pouring part to be fixed on a container, a threaded plug that can be screwed onto the pouring mouth and an automatic opening bushing that can be helically displaced inside the container. pouring part down, towards the container, to open the container. The threaded plug has at least one drive or drag element that acts on at least one stopper element of the automatic opening bushing and which causes the automatic opening bushing to open for the first time the threaded plug inside the spout at a lower position towards the container, in order to open this. When the pouring mouth is then closed with the screw cap, the automatic opening bushing remains in its lower position. The automatic opening bushing has at least two cutting elements and / or protruding downwards, which are arranged on the perimeter of the automatic opening bushing and which form a lower edge thereof. These cutting and / or drilling elements have an essentially rectangular shape. A relatively long longitudinal edge that in the direction of rotation protrudes downward interrupts the rectangular shape forming a triangle that protrudes downward, so that a point protruding downward is formed. With respect to the direction of rotation of the bushing in the front part, the longitudinal edge has an area that descends downwards and then rises again, with the ascending zone having a longer length and an angle smaller than the descending zone being carried out and inclined with a reduced angle with respect to a plane perpendicular to the longitudinal axis.

This form of the elements of cut and / or penetration represents the result of an optimization in terms of requirements in principle contradictory. It has been proven that with the proposed form an especially safe and clean opening of the package is achieved, and at the same time safe for different kinds of containers (in particular laminated cardboard packages with different kinds of weakening as well as PE foil containers). The area of the anterior ascending longitudinal edge acts essentially during the rotation of the bush making a cut, while the entire longitudinal edge including its posterior zone acts at the same time exerting pressure during the downward movement.

The ascending and / or descending zone may have a straight or curved path. The ascending zone is preferably considerably longer than the descending zone and preferably has a length that is at least 2.5 times the length of the descending zone. The descending zone preferably encloses a minimum angle of 40 °, in particular preferably about 50 ° with respect to horizontal (ie a plane perpendicular to the axis of rotation), while the angle of the ascending area with respect to the horizontal is preferably everywhere less than 30 °, more preferably less than 20 °. Between the ascending zone and the descending zone of the longitudinal edge, an obtuse angle, that is to say an angle greater than 90 °, is preferably formed at that point.

The longitudinal edge that protrudes downwardly forms a cutting edge in its descending zone, that is to say that the automatic opening bushing is made in this area as a blade that is thinning towards the longitudinal edge. This facilitates the penetration of the container. Preferably there is also a cutting edge formed in the ascending zone. In this way, for example, the sheet material that stretches elastically above the longitudinal edge can also be effectively cut in this area.

The cutting edge is preferably formed on an inner peripheral surface of the automatic opening bushing. In other words, the automatic opening bushing is preferably sharpened towards the longitudinal edge only by its outer perimeter to thereby form the cutting edge, while the inner perimeter is constant in the area of the longitudinal edge. For this reason the cut material is shifted outwards which contributes to obtain a clean cut appearance of the disc of the material cut out of the container.

Preferably all the cutting and / or penetration elements protrude the same distance downwards. In this way they establish simultaneous contact with the area of weakening of the container and perforate it at the same time at several points. Even if at one of the points it was not successful, the drilling is assured a safe opening. In addition, a relatively large and uniform pressure is exerted on the weakening zone, which is especially advantageous for certain kinds of packages.

To achieve a distribution of forces as uniform as possible, the cutting and / or penetration elements (32a32e) are preferably arranged equally spacedly around the perimeter.

The automatic opening bushing can additionally have at least one fastener element that forms the lower edge with the cutting and / or penetration elements and serves to push down the disc of cut material of the container in order to prevent it from obstructing the spill. The fastener element is arranged in this case following the cutting and / or penetration elements, in the direction of rotation.

In this case, the cutting and / or drilling elements are preferably arranged first consecutively and distributed equidistant along the perimeter, and the distance of the clamping element to the first cutting and / or penetration element found in the direction of rotation is preferably greater than the separation of the cutting and / or drilling elements from each other.

When there is a fastener element then the automatic opening bushing preferably has three to five, in particular four cutting and / or drilling elements. If there is no fastener element it is advantageous if the automatic opening bushing has four to six, in particular five cutting and / or drilling elements. If the number is smaller, the force distribution is less uniform and it is necessary to considerably increase the material thickness of each of the cutting and / or drilling elements, thereby making the manufacturing more expensive. A larger number of such elements instead results in each of the elements being smaller in size, which is also disadvantageous in terms of stability. If the number of elements is too large, the pressure force exerted by each of the elements is too small and no clean cutting effect can be achieved. The optimal number is ultimately the result of a laborious optimization regarding the different, partly contradictory, requirements that the automatic opening cap must meet to be suitable for different kinds of packaging.

For driving, the automatic opening bushing preferably has an external thread that engages with an internal thread of the pouring mouth, so that the automatic opening bushing rotates during its downward movement. The passage of the external thread is preferably chosen in such a way that when unscrewing the threaded plug the automatic opening bushing makes a rotation of less than 360 °, in particular 300 °.

In the screw cap there is preferably a single drive element. Consequently also in the automatic opening bushing there is preferably a single stop element. This stop element is preferably in the area of one of the anterior cutting and / or drilling elements in the direction of rotation of the bushing. However, there may also be several arranged stop elements distributed along the perimeter, although the drag fits only one of them.

In the case of a single drive or drag element, the closing device has a very simple structure. This minimizes manufacturing costs. In particular, it is possible to save material in the closure since the drag system is reduced to an absolute minimum. Thanks to the simple form of the closing device, its manufacturing is also simplified and the rejection of closures that do not satisfy the quality is relatively reduced.

The drag preferably has a drag edge that runs in the axial direction. In that case, the drag edge preferably has an abutment stop surface with respect to the radial direction. The drag can be made in particular in the form of a tooth, with the trailing edge that runs vertically and a back with a maximum inclination angle of 45 °. The drag preferably has a height that corresponds approximately to the height of the pouring mouth. The stop element may be a projection that protrudes from an inner wall of the automatic opening bushing, which has an edge that runs in the axial direction and which only extends in a part of the height of the automatic opening bushing. The projection can then have a bead in relation to the radial direction.

Other advantageous embodiments are deduced from the dependent claims.

Brief description of the drawings

The object of the invention will be explained below using preferred embodiments that are

represented in the attached drawings. These show: fig. 1 a longitudinal section through a closing device according to a first embodiment, in a state prior to its first use;

Fig. 2 the device according to Fig. 1, having the screw plug unscrewed; fig. 3 a side view of the device according to figure 2; fig. 4 a view of the closure according to figure 2 from below, mounted on a container; fig. 5 a longitudinal section through the pouring mouth and the automatic opening of the device

according to figure 1, after its manufacture; fig. 6 a perspective view of the device according to figure 1, from below; fig. 7 a perspective view of the device according to figure 1, from one side; fig. 8 a view of the device according to figure 1, from below; fig. 9a side view of the pouring mouth and the automatic opening bushing according to figure 1; fig. 10 a section by A-A according to figure 9; fig. 11 a longitudinal section through a closure according to the invention, in accordance with a second form of

realization; fig. 12 a perspective view of the closure according to figure 11, and fig. 13 a view of the closure according to figure 11 below, mounted on a container.

Ways for carrying out the invention

An exemplary embodiment of a closing device or automatic opening closure is shown in Figures 1 to 10. This kind of closures are placed on containers with a fluid content, in particular on cardboard beverage containers with an inner sheet. The container already preferably has a predefined pour hole in this area but still tightly closed. The cardboard is already preferably perforated or otherwise weakened, but the sheet below is still intact.

The device is made of plastic by an injected casting process, the different parts thereof being made of the same plastic or of different plastics.

As can be seen from figure 1, the device essentially has a pouring mouth 1, a screw cap 2 and an automatic opening bushing 3. Preferably there is additionally a guarantee band 4 which is preferably made of the same piece with the same screw cap 2. The pouring mouth 1 and the automatic opening bushing 3 are also preferably manufactured together in one piece. However, there is also the possibility of manufacturing them separately.

The spout 1 consists essentially of a spout 10 in the form of a bushing, with a through hole and a flange protruding outward from the spout 10, and which is formed at a lower end of the spout pouring 10. This flange 13 is welded onto the container or fixed on it in some other way, so that the pouring spout 10 is located above the predefined pouring hole of the packaging.

The pouring spout 10 has an outer thread 12 and an inner thread 14. In the lower area of the pouring spout 10, above the flange 13, bridges 15 are disposed with retained projections 15 ', which protrude as they stand out. will describe later.

The threaded plug 2 preferably has a cylindrical casing wall 21 and a substantially flat cover surface 20. The plug can be threaded by means of an inner thread 22 onto the outer thread 12 of the pouring mouth 1. The wrapping wall 21 is joined with the warranty band 4 through controlled breakage points 23.

From the upper inner part of the plug 2, a peripheral seal lip 26 protrudes downwardly, which in the closed state of the plug sits elastically against the inner face of the pouring spout 10.

The plug 2 has a single carrier 24 protruding inward or downward, which is preferably molded on the inner face of the cover surface 20. The carrier 24 preferably has a triangular basic shape, being curved along a concentric circle with the inner thread 14. An edge of the drag 14 runs in the axial direction, preferably having a stop surface inclined with respect to the radial direction, that is to say forming a bead. In the direction of opening of the plug 2 there is a backward side of the trailing edge, the back having a maximum inclination angle of 45 °. The height of the drag 24 corresponds approximately to the height of the pouring mouth 1, in particular the pouring spout 10.

The automatic opening bushing 3 is made in the form of a hollow cylinder and has a through hole. It consists essentially of a ring 30 with an external thread 31 and cutting and / or drilling elements 32a 32e projecting from the ring 30 downwards approximately in the vertical direction. These cutting and / or penetration elements 32a-32e are distributed along the perimeter of the automatic opening bushing 3 located 33 apart from each other and form a lower edge thereof. At this edge, at least one fastener element 35 may also be present. These elements are described in more detail below. The bushing 3 has at least one, preferably exactly one stop element 36, as can be seen in Figure 2. The stop element 36 is a projection protruding from an inner wall of the automatic opening bushing 3, which has an edge that runs in the axial direction and preferably extends only along a part of the height of the automatic opening bushing 3. The projection preferably has an inclined abutment surface relative to the radial direction. The projection preferably extends in the area of the external thread 31, the external thread 31 extending along a height greater than the projection. The stop element is preferably located in the direction of rotation of the bushing 3 in the area of the first cutting and / or penetration element 32a, and may be arranged in the front or rear area thereof or between means.

In figure 1 the plug 2 is threaded on the pouring mouth 1 and the automatic opening bushing 3 is located inside the pouring spout 10, without protruding below this or the flange 13. The guarantee band 4 It is intact. This is the situation that exists before the first use of the closure, and in this position the closure can be mounted on the container.

If s now unscrew the plug 2 then the drag 24 trips over the stop member 36. This can be seen in Figure 6. If its surfaces are made inclined, at least in part a positive coupling reinforcing takes place. the connection between the cover 2 and the bushing 3.

The outer thread 31 of the bushing engages the inner thread 14 of the pouring mouth 1, so that when the screw 2 is unscrewed for the first time, the bushing 3 rotates helically downwards. When the plug 2 is removed, the coupling between the drive 24 and the coupling element 26 is canceled.

In figure 2 the plug 2 is removed, the controlled break points 23 of the guarantee band 4 have been broken and the bushing 3 has moved downwards, so that it is already secured only with its upper part in the lower zone of the pouring spout 10, but protruding downwards with its teeth 32a-32e of the flange 13. This is the situation that exists after the closure is first opened.

In figure 4 the position of use is clearly represented again, where it can be seen that a piece D, which previously defines the pouring hole of the container K, is not completely separated, but remains fixed thereto along A small sector However, it is kept in an open position due to at least one of the cutting and / or drilling elements 32e.

The bushing 3 now remains in this lower position, even if the cap 2 is reinstalled and screwed on.

As can be recognized by Figure 3, this embodiment has a total of 5 cutting and / or drilling elements 32a -32e. These are preferably made all with the same height. These elements are arranged equidistant along the perimeter of the bushing 3.

They preferably have the same shape and the same size. They have an essentially rectangular shape, where in each case a longitudinal edge that goes down interrupts the rectangular shape. It is made with inclination, decreasing the height of the elements backwards in the direction of rotation of the bushing 3. The longitudinal edge is relatively long, so that it is greater than the separations 33 between the elements. It is preferably at least twice as long as the gap 33 between them.

In this example, the longitudinal edge is made relatively bluntly, so that the elements act rather or exclusively as pushers or perforators and not as cutting elements.

Now, as it is represented in Figures 11 to 13, they can also be made as cutting elements, without the need to essentially modify their basic shape. In the other preferred embodiment shown here, a longitudinal edge which in the direction of rotation of the bushing 3 first descends down and then rises, so as to have been formed instead of the longitudinal straight-edged edge according to FIG. that a tip that protrudes down forms. The ascending zone is made longer and flatter than the descending zone that acts as a cutting edge. In the present example, the length of the ascending section is approximately three times the length of the descending section. The descending section has an angle of about 50º with respect to the horizontal, (that is to say with respect to a plane perpendicular to the direction of rotation), while the ascending section only forms an angle of about 12º with respect to the horizontal. Between the ascending and the descending section an obtuse angle is formed, which in this case is about 118º. Both the descending and the ascending sections are made as a knife as a cutting edge. For this, the automatic opening bushing becomes thinner towards the cutting edge or narrows in the form of a blade towards the cutting edge. In the present case, this thinning only takes place on the outer side of the schematic opening bushing. The inner enveloping surface of the automatic opening bushing instead is cylindrical in the area of the cutting edge. Thus, when cutting, the cutting edge moves the cut material outward thus contributing to obtain a clean cut appearance.

In the example of Figures 11 to 13 there are a total of four cutting and / or drilling elements 32a-32e, followed by a single pusher 35. The cutting elements 32 have all the same sizes and have the same shape. The fastener 35 also has approximately the same width or length, but has no cutting tip and is therefore smaller. The distance of the fastener element 35 to the first cutting and / or piercing element 32 located in the direction of rotation is greater than the separation of the teeth 32 from each other.

These embodiments have the advantage that it is no longer positioned exactly on the predefined pour hole. Thanks to their relatively long or wide cutting and / or perforation elements in the direction of the bushing 3, they can also contact the cutout separated from the perforation and exert sufficient pressure to detach the cutout D from the container. In addition, thanks to these elements a relatively strong thread slope can be chosen between the bushing 3 and the pouring spout 10, so that a turn of less than 360 °, in particular 300 °, is enough to open the closure and push down the cutout D.

A possibility of manufacturing a closure of this class is shown in Figure 5. The lid is injected separately, but the bushing 3 and the pouring mouth 2 are manufactured in one piece. The bushing 3 partially protrudes above the pouring spout 2, being connected with the pouring part 2 by means of connecting bridges 5. Once the piece is injected the bushing 3 is inserted completely into the pouring spout 20, with which break the bridges 5.

A preferred embodiment of a first opening identification is shown in Figures 7 to 10. This type of identification can not only be used in this closure but in all closures that have a spout with a flange and a cover that can be screwed onto the spout.

On the upper face of the flange 13 and starting at the pouring spout 10, several bridges 15 are molded that run parallel to a tangent to the pouring spout 10, and parallel to each other. Its free ends are preferably located on a common circle that runs concentric to the outer perimeter of the pouring spout 10. One

or several bridges 15, in this case two, can also run perpendicular to the remaining bridges 15. This can be seen in Figure 10. The free ends form a recessed retaining projections 15 ’as can be seen in Figure 9.

As shown in Figure 7, the guarantee band 4 is injected together with the cap 2 through controlled break bridges 23, preferably completely enclosing the cap 2. In the state of the closure that has not been opened still, the retention bridges 40 of the guarantee band 4 are fitted with the retention projections 15 'preventing the relative relative rotation between the plug 2 and the pouring mouth 1, as can be seen in Figure 10. At turning the plug 2 the controlled break bridges 23 are released due to axial traction and the guarantee band is completely separated from the plug 2.

Preferably, there are still connecting bridges 6 between the plug 2 and the guarantee band 4, which are preferably wider than the bridges 23. They are preferably arranged uniformly distributed along the perimeter of the plug, as can be recognized, for example, in the Figure 8. In the example shown here there are three such bridges 6. However, their number may vary. These bridges facilitate and shorten the time of the injected smelting process, since a relatively significant amount of material can be transported through these bridges. Once the plug is manufactured and preferably before proceeding with the assembly of the closure, these bridges 6 are broken. They are preferably cut with a knife or a laser beam. This kind of connecting bridges can be used in all embodiments. They can also be used in all kinds of individual parts that are injected together. This manufacturing process is not limited to the closures according to the invention described herein.

Other forms of the automatic opening bushing 3, in particular its cutting and penetration elements, fit. The number of teeth can suffer considerable variation. In addition, the interior and exterior threads mentioned above may be continuous or only partial threads.

Reference List

1 Pouring nozzle 10 Pouring spout 12 External thread 13 Flange 14 Internal thread 15 Bridge 15 ’Retention boss

2 Screw cap 20 Cover surface 21 Envelope wall 22 Internal thread 23 Controlled break points 24 Tracker 26 Seal lip

3 Automatic opening bushing

30 Ring

31 External thread

32nd First drilling element

32b up

32e Second to fifth drilling element

33 Separation 34 Second cutting tooth

35 tooth bra

36 Stopper element

4 Warranty band 40 Retention bridge

5 Junction Bridge

6 Union Bridge

K Cardboard container D Cutout

Claims (15)

1. Plastic closure device, with a spout (1) for fixing on a container, with a screw cap (2) that can be screwed onto the pouring mouth (1), and with an automatic opening bushing (3) which, to open the container, can be moved inside the pouring mouth (1) helically down towards the container, the screw plug (2) presenting at least one drive (24) acting on at least one stop element (36) of the automatic opening bushing (3) and causing the screw plug (2) to open for the first time ) the automatic opening bushing (3) is moved inside the pouring mouth (1) to a lower position towards the container in order to open it, and during the subsequent closing of the pouring mouth (1) by means of the screw plug (2) the automatic opening bushing (3) remains in its lower position, and the automatic opening bushing (3) having at least two cutting and / or drilling elements (32a-32e) protruding downwards, which are arranged on the perimeter of the automatic opening bushing (3) and forming a lower edge of this, the cutting and / or perforation elements (32a-32e) having an essentially rectangular shape, in which a longitudinal edge that protrudes downwards interrupts the rectangular shape, forming a triangle that protrudes downward, so that a tip is formed that it protrudes downwards, the longitudinal edge presenting an area that, in relation to the direction of rotation of the bushing (3), has an area that descends downwards and then an ascending zone, characterized in that the ascending zone is longer and is flatter that the descending zone.

2.

Closing device according to claim 1, wherein the ascending zone of the longitudinal edge has a length that is at least 2.5 times the length of the descending zone.

3.

Closing device according to claim 1 or 2, wherein an obtuse angle is formed between the ascending zone and the descending zone of the longitudinal edge.

Four.

Closing device according to one of claims 1 to 3, wherein the longitudinal edge protruding downwards forms a cutting edge in its descending part.

5.

Closing device according to claim 4, wherein the longitudinal edge protruding downward forms a cutting edge both in its descending part and also in its ascending part.

6.

Closing device according to claim 4 or 5, wherein the cutting edge is formed on an inner peripheral surface of the automatic opening bushing.

7.

Closing device according to one of the preceding claims, wherein the cutting and / or drilling elements protrude down the same distance.

8.

Closing device according to one of the preceding claims, wherein the cutting and / or drilling elements (32a-32e) are arranged uniformly distributed on the perimeter.

9.

Closing device according to one of the preceding claims, wherein the automatic opening bushing

(3) presents four to six, in particular 5 cutting and drilling elements (32a-32e). 10. Closing device according to one of the preceding claims, wherein the automatic opening bushing (3) has at least one fastener element (35) that together with the cutting and / or perforation elements (32a-32e) forms the lower edge.

eleven.

Closing device according to claim 10, wherein the automatic opening bushing (3) has three to five, in particular four cutting and / or drilling elements (32a-32d) and a fastener element (35).

12.

Closing device according to one of the preceding claims, wherein the automatic opening bushing

(3) has an outer thread (31) that fits with an inner thread (14) of the pouring mouth (1), so that the automatic opening bushing (3) is rotated during its downward movement.

13.

Closing device according to claim 12, wherein the outer thread has a slope chosen in such a way that the automatic opening bushing makes a rotation of less than 360 ° when unscrewing the screw cap.

14.

Closing device according to one of the preceding claims, in which a single drive (24) is present.

fifteen.

Closing device according to one of claims 1 to 14, wherein on a flange (13) of the pouring mouth (1) bridges are formed with protruding projections (15 ') running parallel to a tangent of a spout of discharge (10) into which the bridges (15) of a guarantee band (4) that at least partially surround the plug (2) attached to it penetrate.