Abstract:
A closing device arranged above a pierceable point of a closed container including a lower part with a cylindrical discharge nozzle, a screw cover and a piercing element. The piercing element, which is open on both sides, is displaced downwards in an axial direction in a screw-like manner in a screw cover in the lower part of the closing device. The piercing element has two cutting elements offset at an angle which produce a continuous, interconnected cutting line, and a displacing element which shifts a partially cut-out tab of the container from a region of the discharge nozzle.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a closure device of plastic which may be attached via a piercable location of a closed receptacle and which has a bung-like lower part with a cylindrical pour-out spout which is connected or connectable to the receptacle, and a screw cap which may be pushed onto the lower part, as well as a cylindrical piercing element which in the axial direction is open on both sides and which is displaceably mounted in the lower part, and during a screwing-off movement of the screw cap for the first time the piercing element moves helically downwards. 
   2. Discussion of Related Art 
   Closure devices of plastic and having three parts, as described above, and having a bung-like lower part with a cylindrical pour-out spout, of a cylindrical piercing element movable therein and a screw cap which moves the piercing element are known in varied forms. Such closure devices are attached to soft-packaging receptacles. The receptacles have multi-layered films which usually have one or more paper or cardboard layers, one or more plastic film layers and at least one blocking layer, for example of aluminium. In the region of the closure devices to be attached, the packaging has suitable pre-punched piercing locations. Usually, according to the piercing element of the closure device, only the innermost-lying compact plastic film layer and the aluminium layer need to be severed. 
   With most known forms the piercing element is designed so that the piercing element merely exerts a translatory movement towards the inside of the packaging. For example European Patent Reference EP-A-0,328,652 teaches a solution in which the screw cap has a guide-path-like helical line centrically incorporated on an inner wall, while the piercing element has a similar counter-running thread and simultaneously the piercing element has cams which prevent a rotation relative to the pour-out bung. A solution is also known from PCT International Publication WO 99/62776. Also Great Britain Patent Reference GB-2241224 teaches a closure device with a bung-like pour-out in which there runs a piercing element with guide cams, wherein the guide cams engage into axially running grooves and simultaneously the piercing element has an inner thread which cooperates with a centric annular wall of the screw cap, wherein the centric wall comprises an outer thread. Simultaneously, a threaded connection exists between the screw cap and the pour-out bung. 
   One solution taught by Great Britain Patent Reference GB-A-2241224 does not function with a piercable location in the packaging but the pour-out bung is welded from the inside to the inner wall of the packaging and an additional film is attached on the inside on the flange of the pour-out bung. Such a closure film may have any of properties which differ from the actual packaging. Accordingly, the piercing element may have practically any shape, for example as shown in FIG. 1 of this publication, or there may be several perforation teeth on the circumference of the piercing element. Completely analogous to this, in the embodiment according to European Patent Reference EP-A-0′328′652 there is a piercing element which has a multitude of perforation teeth on the lower edge, which is also the case with PCT International Publication WO 99/62776 which was mentioned. 
   In contrast, PCT International Publication WO 95/05996 shows a closure device in which the piercing element does not only carry out a purely translatory movement but also a screw movement. The piercing element comprises an outer thread which is meshingly guided into an inner thread in the pour-out bung. The piercing element may be set into a corresponding screw movement by a lug in the screw cap. If the screw cap is screwed off, then the piercing element moves simultaneously in a screw movement downwards into the receptacle to be opened. Also, the piercing element along its lower edge has a multitude of perforation teeth in a completely analogous manner to known devices. 
   Practically all known closure devices obtainable on the market today have significant problems. While initial solutions not documented here functioned practically without perforation teeth and with which the receptacle wall was destroyed somewhere, with perforation teeth it was believed that one could overcome the problem. This however was not the case. One of the main reasons is the fact that all known devices demand a large force effort on opening. Practically with all known devices, over the entire circumference many locations of the films are simultaneously perforated. If the teeth are located at exactly those locations which are vertically above the pre-separated film, then a solution would be possible. This however would demand a fastening of the closure device onto the receptacle which is exact to practically a tenth of a milimeter. This is simply not possible. Accordingly, the teeth also dig into regions of the packaging which are not pre-punched. Thus, not only is considerably more force required but also a pure pulling movement to the film is effected. While films mostly react sensitively to perforations, most films are extraordinarily resistant to tension forces. 
   The embodiment taught by PCT International Publication WO 95/05996, essentially a cutting effect is achieved instead of a piercing effect. Accordingly, the concept with a multitude of perforation teeth does not make sense. Also, with a small rotational angle the complete inner region is cut out of the packaging and falls into the contents of the receptacle. This is not only undesirable and unhygienic, but also during the pouring-out the loose part again and again gets into the pour-out region and leads to uncontrollable pour-out characteristics. 
   SUMMARY OF THE INVENTION 
   It is one object of this present invention to provide a closure device of the type having a simple opening but with features that avoid the disadvantages described in view of the above discussed prior art. 
   A closure device which has the features discussed in this specification and in the claims achieves this object. 
   With the selection of the offset angle α with a size of less than 180°, no complete separation out of the packaging region is possible, whereas with a selection of the offset angle of more than 100°, at the moment at which the displacing element becomes effective, more than half the circumference is severed and thus the already severed part may be folded away. The latter would also be given per se, even if the offset angle is less than 100°, but then there is a significant danger that the displacing element not only pushes the already separated region to the side, but also simultaneously causes the region not yet severed to tear. Finally, with an offset angle of less than 100° the open pour-out region is greatly restricted. 
   Further advantageous design forms of this invention are apparent in view of the claims and their significance and manner of acting, which is explained in the subsequent description with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Each drawing shows a form of the subject-matter of this invention, wherein: 
       FIG. 1  shows a vertical section taken through a closure device in an assembled condition on a receptacle, before opening for the first time; 
       FIG. 2  is a view of the same closure device after opening for the first time, with a screwed-off screw cap, again in the assembled condition, in a diametrical vertical view; 
       FIG. 3  shows the piercing element in a position of manufacture connected as one piece to the lower part, in a diametrical vertical section; 
       FIG. 4  shows a front view of the closure device in the assembled condition in the position of use, wherein only the packaging is shown in a partial view; and 
     FIG.  5  and  FIG. 6  each shows a schematic view of cutting and bending plans for two different offset angles α. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Although this invention essentially relates to the design of the piercing element, for a better understanding of the entire construction the closure device  1  comprising three parts is shown. These three parts are a lower part  2 , which is adheringly attached to a receptacle B, a piercing element  3  which is screwably movably mounted therein and a screw cap  4  engaging over the lower part  2 . The lower part  2  has a cylindrical pour-out spout  20 , which at the end merges into a lower flange  21  and comprises an inner thread  22  and an outer thread  23 . The flange  21  serves as an adhering connection to the receptacle B. The receptacle B includes a multi-layered soft packaging manufactured of films, wherein the multi-layered film comprises a so-called pre-punching V which partly passes through one or more layers and thus defines a nominal opening. For opening the receptacle B, the multilayered film has yet to be completely severed in the region of the pre-punching V. The flange  21  of the lower part may be welded or adhered on the multi-layered film of the receptacle B. The pre-punching V defines a circular surface which is within the opening of the cylindrical pour-out spout  20 . The diameter of the pre-punching V is a few percent smaller than the diameter of the pour-out spout  20 . In contrast, the diameter of the pre-punching V corresponds accurately to the diameter of the piercing element  3  or the circular path which the cutting elements of the piercing element define with their movement. The inner thread  22  of the cylindrical pour-out spout  20  is a coarse thread. Thus, the thread height is relatively large and the thread has a larger pitch. Thus, with a rotation of about 360° or less the piercing element  3  is moved from its original assembly position, as shown in  FIG. 1 , into the lower position of use according to FIG.  2 . Accordingly, the outer thread  23  is a fine thread. Thus, the thread  23  only has a slight height of the thread flanks and the pitch of the thread is flat. In order to screw off the screw cap  4  it needs to undergo several rotations. 
   The actuation of the piercing element  3  is effected by the screw cap  4 . The screw cap  4  has a cover surface  40  on which a circumferential outer wall  41  borders. The outer wall  41  has an inner thread  42  which is designed as a fine thread, matching the outer thread  23  of the cylindrical pour-out spout. An annular wall  43  running concentrically to the outer wall  41  is integrally formed on the lower side of the cover surface  40 . Means in the form of lugs  44  are integrally formed on this concentric annular wall  43  which has a diameter that is smaller than the inner diameter of the piercing element. With a rotation of the screw cap  4  the lugs  44  drive the piercing element  3  in a counter-running direction. While the screw cap  4  moves upwards, the piercing element is moved downwards because the threads between the screw cap  4  and lower part  2  are orientated running counter to the rotational direction of the thread between the piercing element  3  and the lower part  2 . A guarantee strip  45  is integrally formed at the bottom on the outer wall  41  via break-off bridge locations  46 . This is held in the secured position by retaining cams  24  and the guarantee strip  45  remains here even after opening for the first time, as shown in FIG.  2 . 
   The piercing element  3  which as shown in  FIG. 3  is advantageously manufactured with the lower part as one piece, essentially of an annular wall part  31  with an outer thread  32  which is designed as a coarse thread, matching the inner thread  22  of the lower part  2 . At least two cutting elements  33  and at least one displacing element  34 ,  35  are integrally formed on the annular wall part  31 . The displacing element  34  may be combined with the cutting element  33  or, as evident from  FIGS. 1  to  3  may be designed as a separate element  35 . In the section drawings according to  FIGS. 1  to  3  in each case only one cutting element  33  is recognized. Only in the front view according to  FIG. 4  are both cutting elements  33  visible. The cutting elements  33  which roughly have a triangular shape open into a terminal perforating tooth  36 . An arrow D in each case shows the rotational direction of the piercing element. A cutting edge  37  connecting directly to the perforation tooth is integrally formed on the edge at the front in the rotational direction. The cutting edge  37  with the preferred embodiment form merges into a displacing edge  38  which thus forms the displacing element  34  and is a part of the cutting element  33 . On the inner surface of the cutting element  33  above the cutting edge  37  there is integrally formed a lug thickening  39  on which a lug  44  bears during the screwing-off movement of the screw cap for the first time and thus sets the piercing element  3  into a screw movement. The displacing edge  38  is optional. As mentioned, an additional, separate displacing element  35  may be designed shorter in the axial direction of the piercing element  3  than the cutting element  33 . Accordingly, the displacing element  35  only comes into contact with the film of the receptacle B when the two cutting elements  33  have at least approximately formed a continuous cutting line. The separate displacing element  35  otherwise has roughly the shape of the cutting elements  33 , but is bluntly cornered and has no perforation tooth but runs in a rounded arc. 
   The action of the closure device according to this invention is explained with reference to FIG.  5  and FIG.  6 . The two cutting elements  33  are arranged following one another by an offset angle α. In the initial position before opening the closure device for the first time the two perforation teeth  36  of the two cutting elements  33  are located at the positions a′ and b′. After a certain advance angle β the two perforation teeth  36  contact the film of the receptacle to be severed at the points A and B. With reference to the rotational direction D the perforation tooth of the one cutting element runs ahead of the second cutting element by an offset angle α. With a further rotation in the direction D the perforation teeth  36  pierce the film and further sever the film, wherein the one cutting element runs through the cutting path from point A to point B, while the other cutting element defines a cutting line from point B to point C. Thus as soon as the piercing element is rotated by the offset angle α there results a continuous cutting line of  2 α which extends from point A to point C. In this position the cutting edge  37  has inwardly penetrated the film of the receptacle at least approximately completely, and the displacing edge  38  and/or the displacing element  35  act from point C. The displacing edge acts from point C while the displacing element  35  in the region VB which lies relatively close to the pre-punching V in the not yet severed region. Then the region cut free is pressed down into the receptacle in the manner of a flap. At the same time the pre-punching V practically serves as a bending line, such as shown in FIG.  2 . The remaining, non-severed region of the pre-punching V is larger or smaller, according to the choice of the offset angle α. The offset angle α must theoretically be at least 90°, however this is not realized in practice and the actual minimum size of the offset angle α must be larger than 100°. The offset angle α must be smaller than 180° in order to ensure that the cutting line is not circumferential and as a result a complete round part is cut out of the film which could fall into the receptacle. Realistically, the maximum offset angle α may be about 170°. The solutions shown in  FIGS. 5 and 6  relate to realistic details. If one operates with a separate displacing element  35  then the offset angle α may tend to be smaller because the displacing element may already be pressed onto the film before the cutting element at the front in the rotational direction has reached the point C, by which the film is pressed slightly downwards and thus a somewhat longer continuous cutting line arises than the theoretical cutting line. 
   In comparison to the previously known piercing elements with a multitude of perforation teeth, the perforation of this invention is effected only at two points. This has one advantage that the required force is smaller. Simultaneously, here a real cutting movement is effected. The cutting edge  37  specifically carries out a movement component perpendicular to the cutting line as well as a component in the direction of the cutting line. However, because the pre-punching V also runs relatively close to the relatively rigid connection of the film to the flange  21  of the lower part  2  a certain shear force is effected. 
   Of course the gradient of the coarse thread between the piercing element  3  and the lower part  2  needs to be directed to the geometry of the cutting elements. The purely vertical length of the cutting edge  37  must be equal to the thread pitch which corresponds to the angle α, which is particularly the case if the displacing element is combined with the cutting elements.