EP3137240B1 - Method and device for producing tear-off lids - Google Patents

Description

Field of invention

The invention relates to a method for producing tear-open lids according to the preamble of claim 1. Furthermore, the invention relates to a device for producing tear-open lids according to the preamble of claim 11.

background

Tear-off lids are known, for example from DE-U 298 17 592 or off DE-U 92 03 953 . With reference to the Figures 1 to 6 a production of tear-open lids known to the person skilled in the art according to the prior art can be briefly explained. Figure 1 shows a cover blank 1. At the beginning of the transport path of a known manufacturing device 20, a stack 12 is shown which contains a plurality of such cover blanks, which are individually stacked and processed along the transport path by different processing stations, cover rings are first formed from the cover blanks and these can then be further processed up to the finished tear-off cover. The cover blanks are, for example, round disks made of coated metal and thus protected against corrosion, in particular made of coated tinplate. For example, they have a diameter of 11 cm. These blanks have already been preformed at their edge 6 by a processing machine, not shown, and the formation of the edge 6 is later used to attach the finished tear-off lid to a container or a can by a seam connection. This is known to the person skilled in the art and is not explained further here.

The conveying device 22, which conveys the lid blanks, the lid rings and the tear-off lids in the manufacturing device 20 along the transport path in the direction of arrow A from one processing station to the next processing station, is formed in particular by two toothed belts running in parallel, on which receptacles for the lid blanks or Cover rings are provided, as will be apparent to those skilled in the art WO 2006/017953 known. This is also not explained further here. At the respective processing stations according to the prior art, which are known to the person skilled in the art and are only shown schematically here, the blank to be processed is lifted from the conveyor device and processed by the processing station and returned to the conveyor device. This is indicated with arrows pointing up and down at the processing stations. In the case of the machining stations, the drive of the machining stations is indicated below the conveyor. This is used to raise and lower the blanks and cover rings and to carry out the respective processing steps.

In a punching processing station 23, a cover ring 2 is first formed from the cover blank 1 by cutting out a central part 30 of the blank and disposing of it as waste. This forms the removal opening of the tear-open cover, which is closed with the tear-off film in a later manufacturing step. A sealing flange 7 remains adjacent to the removal opening 15. The metal material lies bare at the cut edge 31 or the sheet metal of the cover ring 2 is no longer protected there by the coating. In a processing station 24, the edge of the removal opening is pulled up to form a collar 4 and this collar is rolled in a further processing station 25, so that a so-called retort curl 5 is formed becomes. The shape of the curl or the retort curl can be different. The curl that forms the edge of the removal opening ensures that the user of the can is protected from the sharp-edged cut edge when removing the contents of the can.

The manufacturing steps explained so far have been carried out in a position in which the cover blanks and cover rings were arranged with their later upper side or with the sealing flange 7 pointing downwards. This is the preferred embodiment for the present invention as well. As mentioned, the blank or ring is lifted off the conveyor device in the individual processing stations 23, 24 and 25, processed and put back again, whereupon the conveyor device carries out conveying steps which lead the cover blanks or cover rings to the next processing station. If the manufacturing steps are carried out with the sealing flange 7 pointing downwards, as shown, a turning station 26 now follows, which turns the cover rings so that during further processing the sealing flange 7 is at the top after the turning station in the conveyor device 22 and in the processing stations.

Then the tear-off film 8 is sealed onto the sealing flange, which can be done in two stages with a pre-sealing station 27 and a main sealing station 28. The sealing process is also known to the person skilled in the art and is not explained further here. Further processing stations can follow in which the sealing film is embossed, the tear-off tab is positioned and a leak test is carried out. This is also known to the person skilled in the art and is not explained further here. At the end of the known manufacturing device 20, finished tear-off lids 10 are issued, the removal opening 15 of which is spanned by a tear-off film 8 which is sealed on the sealing flange 7. The edge of the removal opening 15 is formed by a retort curl that is bent upwards and outwards 5 formed. The finished tear-off lid 10 can be attached to a can jacket (shown in FIG Figure 5 is only indicated with a wall part 11) are attached and thus closes the box. This takes place in the bottling plant in which the can has been filled with a product. The filled can can be opened later by tearing the tear-off film away from the lid ring by means of its tear-off tab 18, with the result that the removal opening 15 is open. Such tear-off lids have proven themselves.

If the container, which is closed with the tear-off lid, contains a liquid, corrosive filling material, such as salt water, for example, the bare cut edge 31 can corrode. The upward and outward curling and the overlap with the tear-off foil in the case of the tear-off lid with retort-curl shown provide a certain protection against the influence of the product and the bare or possibly corroded cut edge is also not visible, but can ever However, depending on the aggressiveness of the product and the storage time of the filled container, traces of corrosion can still be seen. In EP-A-1 153 840 , which forms the basis for the preambles of claims 1 and 11, it is proposed that the tear-off film is also sealed on the curl itself, as a result of which the cut edge of the can contents is protected by a seal. It turns out, however, that the sealing both on the sealing flange and also on the rolling in production with a high manufacturing rate can hardly be controlled reliably. WO-A 02/790041 mentions in passing that the gap created during the roll-up process can be filled with the heat-seal coating of the tear-off foil without explaining how this would actually be feasible in the industrial production of tear-off foils. Known tear-off foils are only provided with a very thin heat-sealing layer and it is not apparent to the person skilled in the art how this layer can be used to fill the gap when a heat-sealing known to the person skilled in the art is carried out. In the WO-A 02/790041 The suggested solution is therefore hardly feasible in practice. Out EP-B 2 055 736 it is known to provide an outward curl in a container at the mouth of the container, so that the cut edge does not come into contact with water. It is proposed to protect the cut edge there with a modified hotmelt material which contains a thermoplastic elastomer.

Presentation of the invention

The invention is based on the object of creating a method and a production device for tear-open lids, with which a tear-open lid can be produced industrially at high rates and at low costs, which has practically no corrosion of the cut edge even with corrosive filling goods.

In the above-mentioned method for producing tear-open lids, this object is achieved in that a band-shaped strip of plastic is applied to the inside of the collar before the free end of the collar is rolled up.

Because a band-shaped strip is applied, the plastic can be applied with little material expenditure and at high speed, which reliably protects the cut edge from corrosion during the subsequent rolling to form a retort curl.

It is preferred if the band-shaped strip is applied with a uniform thickness and this in particular with a very small thickness, which is only 0.05 mm to 1.0 mm. It is particularly preferred if the band-shaped strip is applied with a thickness of approximately 0.1 mm. The uniform thickness results in a good sealing effect when rolled and can save material and time during application. Particularly the preferred thickness range or the preferred approximate thickness of 0.1 mm results in a good sealing effect with little use of material and high application speed. It is preferred that the band-shaped strip is applied to the cover ring by spraying a liquid plastic, so that work can be carried out quickly and with a high degree of uniformity. The plastic is preferably a plastic that has been liquefied by melting and, in particular, a thermoplastic elastomer that has been liquefied by melting. This results in the desired even and thin application. The height of the tape can be, for example, one to several millimeters and is not critical if it is ensured during the curling that the curling comes into contact with the tape.

The plastic is preferably applied to the rotating cover ring from a spray nozzle that is stationary during application. This variant is mechanically simple and easy to control for the desired accuracy. However, it would also be possible to work with a rotating spray nozzle and a stationary cover ring. In particular, the desired uniform thickness can be achieved if the distance between the spray nozzle and the cover ring is kept constant during spraying. This is preferably carried out in such a way that the cover ring is horizontally displaceable on its support and that the outside of the collar of the cover ring is acted on with at least one roller in order to keep the distance between the inside of the collar and the spray nozzle constant, since the precise and fixed rotatable roller that defines the position of the collar in relation to the spray nozzle. This results in a mechanically simple solution which allows the precise application of the band-shaped strip with a uniform thickness. Solutions are also possible in which the distance between the spray nozzle is continuously adapted via a distance measurement and a displacement of the spray nozzle to the cover ring that does not rotate precisely in the center, but the mechanically simpler solution claimed is preferred.

The invention is also based on the object of creating a manufacturing device for tear-open lids, by means of which tear-open lids can be manufactured at high speed and inexpensively, which do not have the disadvantage mentioned.

This object is achieved in the device mentioned at the beginning with the characterizing features of claim 11.

By providing an application station with which a circumferential band-shaped plastic layer can be applied to the inside of the collar of the cover rings, protection of the rolled-up cut edge is made possible, since the rolled-up contacts the plastic layer that forms a seal.

The device is preferably further designed so that the application station is designed to apply a strip-shaped plastic layer which has an essentially uniform thickness, in particular a thickness in the range from 0.05 mm to 0.5 mm and in particular with a thickness of approx. 0.1 mm. This design provides good protection with low material consumption and a very high processing speed, so that the application station can work at the same rate as the other processing stations of the device. It is further preferred that the application station has a receptacle for a cover ring that can be driven in rotation by a drive and a spray nozzle that is stationary during the application of the tape in order to transfer the plastic over the spray nozzle, which comes to lie in the application station within a cover ring placed on the receptacle, if this has been lifted from the conveyor by the application station, to be applied in liquid form to the rotatingly driven cover ring in the form of a band. This reproducibly results in the desired plastic layer of small thickness.

The plastic is preferably liquefied in that the application station is equipped with a heated extruder Supply to a controllable valve and a heated valve is equipped so that the spray nozzle can be supplied with the melted plastic via the valve for application under pressure. Preferably, the receptacle of the cover ring is horizontally displaceable with respect to its axis of rotation against the force of a spring and at least one roller is provided whose axis of rotation runs parallel to the axis of rotation of the receptacle, the roller being at least partially coplanar with the receptacle and protruding into the area that is occupied by this when the cover ring is raised. Thus, the outside of the collar of a cover ring located on the receptacle can be acted upon by the roller when the cover ring is raised and since the position of the roller is precisely defined, the horizontal position of the raised cover ring is also precisely defined. This allows the distance between the inside of the collar and the spray nozzle to be kept constant in a simple manner, which leads to the desired constant thickness of the plastic application on the inside of the collar. The spray nozzle is moved towards the rotating cover ring, which is horizontally defined by the roller, to carry out the application of the tape, and is moved away again after the application.

Brief description of the drawings

• Figuren 1 bis 5 vertikale Schnittansichten durch einen Deckelrohling, einen Deckelring und einen Aufreissdeckel zur Erläuterung von Bearbeitungsschritten bei der Bildung eines Aufreissdeckels nach Stand der Technik;
• Figur 6 eine schematische Seitenansicht einer Vorrichtung nach Stand der Technik zur Herstellung von Aufreissdeckeln bzw. zur Durchführung der Schritte gemäss den Figuren 1 bis 5;
• Figur 7 eine vertikale Schnittansicht eines Deckelrings bei der Herstellung eines Aufreissdeckels gemäss der Erfindung;
• Figur 8 eine vergrösserte Ansicht eines Teils des Deckelrings von Figur 7;
• Figur 9 den Deckelring von Figur 7 nach dem Einrollen des Randes der Entnahmeöffnung;
• Figur 10 eine vergrösserte Ansicht eines Teils des Deckelrings von Figur 9;
• Figur 11 eine Draufsicht auf den Deckelring eines Aufreissdeckels gemäss der Erfindung;
• Figur 12 eine schematische Darstellung der Bearbeitungsstation zur Aufbringung der Dichtung;
• Figur 13 eine schematische Seitenansicht einer Vorrichtung gemäss der Erfindung zur Herstellung von Aufreissdeckeln mit abgedichteter Schnittkante;
• Figuren 14 bis 17 die Positionierung des Deckelrings in der Bearbeitungsstation und die Bewegung der Spritzdüse bei einer bevorzugten Ausführung; und
• Figuren 18 bis 21 in vergrösserter Darstellung die Positionierung der Spritzdüse für den Auftrag des Kunststoffes.

Further refinements, advantages and applications of the invention emerge from the dependent claims and from the description that follows based on the figures. Show:

• Figures 1 to 5 vertical sectional views through a cover blank, a cover ring and a tear-open cover to explain processing steps in the formation of a tear-open cover according to the prior art;
• Figure 6 a schematic side view of a device according to the prior art for the production of tear-open lids or for performing the steps according to FIG Figures 1 to 5 ;
• Figure 7 a vertical sectional view of a cover ring in the production of a tear-open cover according to the invention;
• Figure 8 an enlarged view of part of the cover ring of FIG Figure 7 ;
• Figure 9 the cover ring from Figure 7 after rolling in the edge of the removal opening;
• Figure 10 an enlarged view of part of the cover ring of FIG Figure 9 ;
• Figure 11 a plan view of the cover ring of a tear-off cover according to the invention;
• Figure 12 a schematic representation of the processing station for applying the seal;
• Figure 13 a schematic side view of a device according to the invention for producing tear-open lids with a sealed cut edge;
• Figures 14 to 17 the positioning of the cover ring in the processing station and the movement of the spray nozzle in a preferred embodiment; and
• Figures 18 to 21 in an enlarged view the positioning of the spray nozzle for the application of the plastic.

Way (s) for carrying out the invention

Introductory with reference to the Figures 1 to 6 the production of tear-open lids known to the person skilled in the art according to the prior art has been explained. Reference is made to this explanation here in order to dispense with repetition.

The procedure according to the invention is described below, with reference to the known device and the known, previously explained manufacturing steps Reference is made to the extent necessary. In particular, in the device and in the method according to the invention for the formation of the cover ring from the cover blank and for the sealing of the tear-off film, the procedure is already known to the person skilled in the art.

Figures 7 and 8 show a cover ring in which the processing step of drawing the edge of the removal opening to form the collar 4 has already taken place. This took place in the processing station 24. In the shown preferred example according to the invention (or in a separate step) an inward curvature has been created at the upper end 34 of the collar 4, which facilitates the later rolling in to form the retort curl. According to the invention, a plastic layer in the form of a tape 32 has also been applied to the inside 40 of the collar 4 in one work step. This plastic layer is preferably applied in a separate processing station 29, as in FIG Figure 13 shown. This processing station 29 is arranged between the pulling station 24 and the rolling station 25.

The band 32 made of the plastic layer forms a seal for the cut edge 31 when it is rolled up, which is shown below. The band 32 is made of a plastic and preferably the band is made of a thermoplastic elastomer (TPE). Such TPE plastics are commercially available and, in particular, also commercially available in qualities that reliably withstand the sterilization temperature during the sterilization of the filled container, so that the seal formed by the tape is retained during the sterilization. As shown, the band is preferably of uniform thickness over the entire height of the band. It is provided as a thin strip, which preferably has a thickness d in the range from 0.05 millimeters to 0.2 millimeters, preferably a thickness of about 0.1 millimeters. The height H of the band can be 1 to 3 mm, for example.

The application according to the invention takes place by spraying on molten, liquid plastic material, preferably the mentioned TPE, with a relative movement of the nozzle and the cover ring. The cover ring is preferred in the processing station 29 ( Figures 12 and 13 ) moves in rotation and thereby moves the inside 40 of the collar 4 past the outlet opening of a spray nozzle which is statically arranged during application and from which the plastic exits. The cover ring is thus raised at the processing station 29, set in rotation and the application is activated when the cover ring has reached the correct position in relation to the outlet opening. After at least one full revolution, when a continuous belt is formed on the inside, the cover ring with the belt 32 is moved back down to the conveyor device, the rotation being stopped so that the cover ring can be placed back on the receptacles of the conveyor device . Then it is conveyed to the roll-in station 25. The plastic of the band 32 cools down as soon as it is applied to the cover ring and solidifies so that the plastic does not flow during further conveyance and the band is stable in the form shown. At most, a coolant, for example in the form of a fan, can be provided in the application station or processing station 29.

The cover ring can be rotated at a high rotational speed when the thin plastic tape is applied, which is understood to mean a rotation of more than 200 revolutions per minute. A preferred speed of rotation is in the range from 400 to 600 per minute.

During application, it is ensured that the distance between the application opening or the spray nozzle and the inside 40 of the collar 4 when the liquid plastic remains essentially constant, so that the thickness of the band 32 is essentially constant and its small thickness is possible. This can take place, for example, in that the cover ring 2 is precisely centered on a receptacle in the processing station 29 and the spray nozzle with the discharge opening is at a defined distance from this receptacle. The transfer from the conveying means with subsequent centering takes time, so that for the very high production rates aimed at, the preferred procedure is that the cover ring in the processing station is pressed with the outside of the collar 4 against a roller that is precisely positioned with respect to the spray nozzle position during application is, whereby the distance between the spray nozzle and the inside 40 of the collar 4 is precisely defined in a simple manner. This is referring to Figure 9 and the Figures 14 to 17 and 18 to 21 explained in more detail.

It can be seen that the band 32 is positioned on the inside 40 of the collar 4 that it is closer to the plane of the sealing flange 7 than to the cutting edge 31. The positioning and dimensioning of the band is approximately such that the band 32 is the lower third of the Collar 4 until the lower half of the collar 4 is covered. A greater height H of the tape is possible, but then the material expenditure for the plastic used increases without this being necessary for further processing or for protecting the cut edge. In practice, the height H will be approx. 1 mm to 3 mm.

According to the Figures 7 and 8 The cover ring provided with the plastic band is provided with a retort curl 5 in the processing station 25 in a known manner. This station 25 works according to the state of the art with the known rolling tools, so that this does not have to be explained in detail here, since this is known to the person skilled in the art. A modification which is obvious to the person skilled in the art results, if necessary, in the tools when the collar 4 is at its upper part Edge 34 has already been pre-bent for curling, which is preferred. It can be seen according to the Figures 10 to 13 , which show the cover ring after the turning station 26, and especially when viewing the Figure 12 that during the formation of the retort-curl 5 the band 32 forms a seal which prevents the entry of liquid into the interior of the retort-curl. Thus, the bare cut edge 31 is protected against the influence of a liquid in the can. It does not matter whether the curling takes place in such a way that the cut edge 31 is partially embedded in the band 32, as shown, or whether it is only in contact with the band 32. Even the opposite, that the cut edge 31 cuts through the band 32 and rests against the metal of the inside 40, does not interfere with the function of the band 32. The usual manufacturing tolerances in the formation of the retort curl 5 therefore play no role. The top view 12 shows the cover ring as it is conveyed into the sealing station 27, in which the tear-off film is sealed over the removal opening.

Figure 13 shows the production device 20 for the tear-off lid, in which a processing station 29 is provided for applying the tape 32 to the lid ring. The processing station 29 is preferably according to Figure 12 and the Figures 14 to 21 educated.

Figure 12 shows a support 50 which is adapted to the cover rings 2 in terms of diameter and shape. A cover ring 2 rests with its sealing flange 7 on the upper side of the support 50. The support 50 can be moved up and down in a known manner as in the other processing stations, so that the support can be moved downwards in the direction of arrow C in the drawing, whereby the support is lowered under the receptacles for the cover ring of the conveyor device 22, whereby the cover ring is returned to the conveyor so that it can be transported to the next processing station 25. On the other hand, the The next cover ring, which is to be received in the processing station 29, is received by the receptacle 50 or lifted off the conveyor device when the receptacle 50 is moved upwards again in the direction of the arrow B. This is basically known to the person skilled in the art in a similar manner from the other processing stations and the drive for moving the support 50 up and down is only shown schematically as box 58. This drive can be designed electrically and / or pneumatically in a known manner.

In the preferred processing station 29, the support 50 is resiliently displaceable in the horizontal direction in the direction of the arrow EF with respect to the vertical central axis 55. This can be done in different ways and is solved in the present example in such a way that a central conical holder 52 is provided, which is fixed in the position of the central axis 55 (but can be rotated about this, which will be explained later) and that elastic spring means, e.g. are provided in the form of a circumferential plastic tube 54, which allow the support 50 to move horizontally in the direction of the double arrow EF by a few tenths of a millimeter to a millimeter or to move perpendicular to the central axis 55. This means that the cover ring can also move by this amount in the direction of the double arrow. The spray nozzle 46, which sprays the plastic material to form the band 32 against the inside 40 of the collar 4 of the cover ring 2, on the other hand, is fixed in its application position (but can be moved into it, which will be explained below). The distance from the spray nozzle 46 to the inside 40 is kept constant during the application of the plastic material in that a roller 45 rotatable about a vertical axis of rotation is arranged adjacent to the support 50. The position of the axis of rotation 47 in the processing station 29 is fixed and is defined in relation to the spray nozzle in its application position, whereby the plastic is applied with a defined thickness.

The displacement drive 48, by means of which the spray nozzle 46 can be displaced in the direction of the double arrow EF, is shown as a box 48 and is, for example, an electric motor or electromagnetic or pneumatic design. This shift of the spray nozzle is still based on the Figures 14 to 21 shown in more detail.

If the support 50 is raised, the cover ring 2 is positioned centrally to the axis 55 by the spring means 54. The spray nozzle 46 has been positioned by its drive 48 to the axis 55 or in the direction E, which is in the Figures 14 and 15 as well as 18 and 19 can be seen. In this position, the spray nozzle can dip into the cover ring 2 when it is lifted in the direction of arrow B. There is also enough space for the preferred inward curvature of the edge 34 of the collar 4 or the spray nozzle is not an obstacle for the lifting movement of such a cover ring in this retracted position. The cover ring 2 or the support 50 and its holder 52 is set in rotation about the axis 55 by the drive 58, for example at the mentioned speed of rotation of 600 per minute. At the end of the lifting movement of the cover ring 2, it comes into contact with the outside of the collar 4 with the outside of the roller 45, since the roller 45 is arranged in the processing station so that it protrudes into the area occupied by the lifted cover ring. The Figures 14 and 18th show the position when lifting just before the collar 4 touches the roller 45. The Figures 15 and 19th show the position in which the lifting movement is complete and the collar 4 rests against the roller 45. Since the position of the roller 45 in the processing station 29 is precisely defined in the horizontal direction, the position of the collar 4 where it contacts the roller 45 is also precisely defined. Thanks to the spring means 54, the cover ring can adjust itself in the horizontal position so that it takes over the position of the roller 45. The role 45 is rotatable but usually not self-propelled because it takes over the rotation of the cover rings.

When the lifting is finished and the cover ring has the Figures 12 , 15th and 19th When the position shown is reached, the spray nozzle 46 is moved in the direction F by its drive 48 and assumes its fixed application position. Since the position of the roller 45 in the processing station is precisely given in its distance from the spray nozzle, the inside 40 of the collar 4 is positioned opposite the spray nozzle at a precise distance for spraying the plastic material on the inside 40 when the spray nozzle 46 is in its end position Direction F has reached what is in the Figures 16 and 20th is shown. The recess 49 in the spray nozzle 46 allows the spray nozzle 46 to be moved towards the collar 4 despite its curvature at the end 34. Once the spray nozzle 46 has reached its end position, spraying is started and takes place during one full revolution (or at most during several full revolutions) of the Cover ring instead. The Figures 12 , 17th and 21st show the spraying through the spray nozzle. The band 32 is thus formed from plastic in a thickness that can be precisely selected. The height H of the band 32 results from the choice of spray nozzle. The spraying of the plastic is stopped and the spray nozzle 46 is moved back in the direction of arrow E by its drive 48. Furthermore, the rotation of the support 50 and holder 52 is ended and the support 50 is moved downwards in the direction of arrow C, the cover ring losing contact with the roller 45 again. The cover ring 2 equipped with the belt 32 is placed back on the conveyor and the next conveying step takes place and conveys the cover ring equipped with the plastic belt 32 to the next processing station 25.

The spray nozzle 46 can be supplied with the liquid, melted TPE plastic in a fundamentally known manner by inserting the plastic in an extruder 60 is melted and extruded and is fed, for example, through a heated hose line 61 in liquid and under pressure to the processing station. This is only indicated schematically with lines, so that the specific design of the entry of the line into the head containing the spray nozzle is not shown. A controllably openable and closable valve 62, which is preferably also heated, causes the beginning and the end of the injection of the plastic. A control 63 can control the described sequence of lifting the conveyor, rotating the support with the cover ring around the axis 55 and moving the spray nozzle 46 and the start and end of spraying and moving the spray nozzle back, stopping the rotation and lowering the support Taxes. This control can be a control provided at the processing station 29 or is a control common to several or all of the processing stations and the conveying means 22.

The mentioned Figures 14 to 17 show an example of the drive 48 of the spray nozzle 46 in more detail. This can be moved horizontally in a linear guide in the direction E - F, which is effected here via an eccentric drive. In the Figures 18 to 21 the positioning of the spray nozzle to the inside of the collar 4 is shown enlarged. The channel for the plastic inside the spray nozzle 46 is also shown with broken lines. The displacement of the support 50 and thus of the cover ring 2 when it comes into contact with the outside of the roller 45 is shown in FIG Figure 19 indicated by the arrows G.

While preferred embodiments of the invention are described in the present application, it should be clearly pointed out that the invention is not restricted to these and can also be carried out in other ways within the scope of the following claims.

Claims (16)

1. Method for producing tear-off lids,
   wherein

   - from a lid blank (1) a lid ring (2) having a central removal opening (15) which is surrounded by a sealing flange (7) is formed by means of a punching process;

   - the edge of the removal opening is formed by drawing to a collar (4) projecting away from the sealing flange (7);

   - the collar (4) is curled at the free end (34) thereof;

   - a tear-off film (8) is sealed onto the sealing flange (7);

   characterized in that before the curling of the free end of the collar (4), a band-shaped strip (32) of plastics is applied to the inside (40) of the collar.
2. Method as claimed in claim 1,
   characterized in that the band-shaped strip is applied at a substantially even thickness.
3. Method as claimed in claim 1 or 2,
   characterized in that the band-shaped strip (32) is applied at a thickness which amounts to 0.05 mm to 0.5 mm and, in particular, that the band-shaped strip is applied at a thickness of approximately 0.1 mm.
4. Method as claimed in one of the claims 1 to 3, characterized in that the band-shaped strip (32) is applied by spraying a liquid plastics material onto the lid ring.
5. Method as claimed in claim 4,
   characterized in that the plastics is a plastics liquefied by melting and particularly in that the plastics is a thermoplastic elastomer liquefied by melting.
6. Method as claimed in claim 4 or 5,
   characterized in that the plastics is applied onto the rotating lid ring from a spray nozzle which is stationary in the coating position.
7. Method as claimed in claim 6,
   characterized in that, during the spraying on, the distance between the spray nozzle and the lid ring is kept constant.
8. Method as claimed in claim 7,
   characterized in that during the spraying on, the lid ring is held horizontally displaceable and in that the outside of the collar is acted upon by at least one roller (45) in order to keep the spacing of the inside (40) of the collar (4) from the spray nozzle (46) constant.
9. Method as claimed in one of the claims 1 to 8, characterized in that, in order to apply the band of plastics, a lid ring (2) is lifted lying horizontally and toward the end of the lifting movement is acted upon by a horizontally immovably positioned roller (45), which extends into the lifting region of the lid ring, in that after the lifting, a spray nozzle (46) is moved toward the inside of the collar (4), in that after reaching the end position of the spray nozzle (46), the spraying on of the plastics onto the rotatingly driven lid ring takes place, in that after the application of the peripheral band (32), the spray nozzle is moved away from the inside of the collar (4) and in that the lid ring is lowered in the direction of a conveying device.
10. Method as claimed in one of the claims 1 to 9, characterized in that when the collar (4) is formed, the free end (34) of the collar is curved inwardly.
11. Apparatus (20) for producing tear-off lids (10), wherein on the upper side of the lids a tear-off film (8) is sealed on a sealing surface (7) arranged round a removal opening (15), wherein the apparatus (20) comprises a conveying device (22) for lid blanks (1), lid rings (2) and tear-off lids (10) as well as processing stations (23-28) which are provided one after another for processing the lid blanks, lid rings and tear-off lids, wherein a first processing station (23) is provided as a punching station for forming a lid ring (2) from the lid blank (1), a second processing station (24) is provided for forming a collar (4) of the lid ring (2), extending from the lower side, and a third processing station (25) is provided which is configured for curling the collar toward the tear-off lid upper side and outwardly, and further at least one sealing station (27, 28) is provided which is configured for sealing a tear-off film (8) onto the sealing surface (7), characterized in that in the conveying direction between the second processing station (24) for forming the collar and the third processing station (25) for curling the collar, a further processing station (29) is provided which is configured as a coating station for applying a peripheral, endless plastics layer (32) of substantially even thickness on the inside (40) of the collar (4), and in that the third processing station (25) is configured for curling such that the curl (5) comes into contact with the plastics layer (32).
12. Apparatus as claimed in claim 11, characterized in that the coating station (29) is configured for applying a band-shaped plastics strip (32) which has a substantially even thickness, particularly a thickness in the region of 0.05 mm to 0.5 mm and particularly a thickness of approximately 0.1 mm.
13. Apparatus as claimed in one of the claims 11 or 12, characterized in that the coating station (29) comprises a receptacle (50) which is rotatably drivable by means of a drive (58) for a lid ring (2) and comprises a spray nozzle (46) which is stationary in the coating position and is configured to apply the plastics via the spray nozzle (46), which comes to lie in the coating station within a lid ring (2) placed on the receptacle, in a liquid form and band-shaped onto the rotatingly drivable lid ring (2).
14. Apparatus as claimed in one of the claims 11 to 13, characterized in that the coating station comprises an extruder (55), a heated feed line (61) and a heated and controllable valve (62), wherein the spray nozzle (46) can be supplied with the melted plastics by means of the valve.
15. Apparatus as claimed in claim 13 or 14, characterized in that the receptacle (50) is displaceable horizontally relative to its rotational axis (55) against the force of a spring (54), and in that at least one roller (45) is provided, the rotational axis (47) of which extends parallel to the rotational axis of the receptacle and the roller (45) is arranged at least partially coplanar with the receptacle (50) and extends with the outside of said roller into the lifting region, into which lifting region, on lifting, a lid ring comes to lie in the processing station at the end of the lifting movement, so that the outside of the collar (4) of a lid ring (2) situated on the receptacle can be acted upon by the roller (45).
16. Apparatus as claimed in one of the claims 11 to 15, characterized in that said apparatus has a horizontally movable spray nozzle (46) which in its one end position of the travel path (E-F) lies closer to the rotation axis (55) and in its other end position of the travel path lies closer to the inside of the collar (4) of a lid ring (2) situated in the processing station.

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