METHOD AND DEVICE FOR PRODUCING TEAR-OFF LID

Description

Field of the invention

[0001] The invention relates to a method for producing tear-off lids according to the preamble of patent claim 1. background

[0002] Tear-off ends (so-called Peel Off Ends or POE) are known, for example from DE-U 298 17 592 or from DE-U 92 03 953.

[0003] With reference to the Figures 1 to 6 A prior art production of tear-off lids known to the person skilled in the art from WO 2018 / 191828 A1 can be briefly explained.

[0004] Figure 1 shows a lid blank 9. At the beginning of the transport path of a known manufacturing device 10, a stack 11 is shown, which contains a plurality of such lid blanks 9, which are individually stacked and processed along the transport path by various processing stations 14, 19, 21, 25, 26, wherein lid rings 8 are first formed from the lid blanks 9 (see Fig. 2) and then to the finished tear-off lid 27 (see Fig. 5 ) can be further processed. The lid blanks 9 are, for example, round or oval discs made of coated and thus corrosion-protected metal, in particular coated tinplate or aluminum sheet. They have a diameter of, for example, 11 cm. These blanks 9 have already been preformed at their edge 12 by a processing machine (not shown), and the formation of the edge 12 later serves to attach the finished tear-off lid 27 to a container 28 or a can by means of a seam connection. This is known to the person skilled in the art and will not be explained further here.

[0005] The conveyor device 13, which conveys the lid blanks, the lid rings and the tear-off lids in the manufacturing device 10 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 parallel toothed belts, on which receptacles for the lid blanks or lid rings are provided, as known to the person skilled in the art from WO 2006 / 017953. This will not be explained further here either. 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 or ring to be processed is lifted off the conveyor device, processed by the processing station and returned to the conveyor device. This is indicated at the processing stations by up and down arrows. At the processing stations, the drive of the processing stations is indicated below the conveyor.This is used to lift and lower the blanks and cover rings and to carry out the respective processing steps.

[0006] In a punching processing station 14, a lid ring 8 is first formed from the lid blank 9 by punching out a middle part 16 of the blank downwards and usually disposed of as waste (see Fig. 2 ). This forms the removal opening 17 of the tear-off lid, which is sealed with the tear-off film 24 in a later production step. A sealing flange 18 remains adjacent to the removal opening 17. In a processing station 19, the edge of the removal opening 17 is pulled upwards to form a collar 20 (see Fig. 3). This collar 20 is rolled in a further processing station 21 toward or away from the removal opening, forming a so-called "curl." This curl 22, which then forms the edge of the removal opening 17, ensures that the user of the can is protected from the sharp cutting edge 23 when removing the contents of the can. Depending on the extent of the curl, it is referred to as a "C-curl" (cutting edge not located within the curl) or a "retort curl" (cutting edge located within the curl). Curls that are rolled away from the removal opening are referred to as "reverse C-curls" or "reverse retort curls." In the case shown here, a so-called retort curl 22 is formed (see Fig. 4 ).

[0007] The previous manufacturing steps were carried out in a position in which the lid blanks 9 and lid rings 8 were arranged with their future top side or with the sealing flange 18 facing downwards. This is also a preferred embodiment of the present invention. As mentioned, the blank 9 or the ring 8 is lifted from the conveyor device 13 in the individual processing stations 14, 19 and 21, processed and placed back again, whereupon the conveyor device carries out conveying steps which guide the lid blanks 9 or lid rings 8 to the next processing station. If the manufacturing steps are carried out with the sealing flange 18 facing downwards, as shown, a turning station 23 now follows, which turns the lid rings 8 so that during further processing the sealing flange 18 is at the top after the turning station 23 in the conveyor device 13 and in the processing stations 25, 26.

[0008] The tear-off film 24 is then sealed onto the sealing flange 18, which can be carried out in two stages with a pre-sealing station 25 and a main sealing station 26. The sealing process is also known to those skilled in the art and will not be explained further here. Further processing stations may follow, in which the sealing film 24 is embossed, the tear-off tab 15 is positioned, and a leak test is carried out. This is also known to those skilled in the art and will not be explained further here. At the end of the known production device 10, finished tear-off lids 27 are dispensed (see Fig. 5 ), the removal opening 17 of which is covered by a tear-open film 24 which is sealed to the sealing flange 18. The edge of the removal opening 17 is formed here by the retort curl 22. The finished tear-open lid 27 can be attached to a can jacket (which is Figure 5only indicated by a wall portion 28) and thus closes the can. This occurs during the filling process, in which the can has been filled with a product. The filled can can be opened later by tearing the tear-off film 24 away from the lid ring 8 using its tear-off tab 15, thereby exposing the removal opening 17.

[0009] In the previously described state-of-the-art system, a punching or cutting burr is created on the intended outer side (underside) of the produced lid ring during the punching process of the lid blank. This is particularly suboptimal if a "reverse curl" (curling away from the removal opening) is subsequently created. From a production-technical perspective, it would be desirable if the (unavoidable) punching or cutting burr were created on the intended inner side (top side) of the produced lid ring, with the process flow and system concept otherwise unchanged.

[0010] DE 26 37 085 A1 discloses a device for ejecting punching waste or punched parts from a punching tool with a stripper. The punching waste or punched part is ejected through the die using compressed air. Description of the invention

[0011] The invention is based on the object of providing technical solutions with which the previously described known and established methods and devices for producing tear-off lids can be modified with the least possible plant-technical expenditure in such a way that the punching or cutting burr is created on the other side of the lid with the process sequence and plant concept essentially unchanged.

[0012] This problem is solved by the method according to patent claim 1.

[0013] According to this, a first claimed aspect of the invention relates to a method for producing a tear-off lid. A lid ring with a central removal opening surrounded by a sealing flange is formed from a lid blank by punching with a punching tool. The punching tool comprises a die and a cutting punch.

[0014] The edge of the removal opening is then formed into a collar by drawing, which protrudes from the sealing flange on the side that forms the inside of the lid during the later intended use of the lid to be produced (intended inside of the lid).

[0015] The collar is then rolled up at its free end and a tear-off film is then sealed or glued onto the sealing flange, on the side that will form the outside of the lid during the later intended use of the lid to be produced (intended outside of the lid).

[0016] According to the invention, during punching, the die is arranged on the side that forms the inside of the lid during the later intended use of the lid to be produced (intended inside of the lid) and the cutting punch is moved into the die from the side that forms the outside of the lid during the later intended use of the lid to be produced (intended outside of the lid) while punching out a punching lump.

[0017] The punching slug thus produced is conveyed by compressed air through the die to a conveyor device, with which it is removed from the tool area.

[0018] The invention makes it possible to modify the currently known and established methods and devices for producing tear-off lids with very little effort in such a way that, with essentially unchanged process sequence and system concept, the punching or cutting burr is created on the side which forms the outside of the lid during the later intended use of the lid to be produced (intended outside of the lid).

[0019] In a preferred embodiment of the process, a lid blank made of a ferromagnetic material is used. A magnetic conveyor belt is used as the conveying device for removing the punching slugs from the tool area. This allows for reliable handling and removal of the punching slugs in the tightest of spaces and with a minimum of moving components.

[0020] In another preferred embodiment of the method, a vacuum conveyor belt is used as the conveying device for removing the punching slug from the tool area. This also allows for reliable handling and removal of the punching slugs in a very confined space and with a minimum of moving components, and both ferromagnetic and non-ferromagnetic lid blanks, e.g., made of aluminum, can be processed.

[0021] Magnetic and vacuum conveyor belts are well known in the field of conveyor technology and therefore do not need to be explained in detail here.

[0022] The compressed air used to convey the punching slug to the conveyor is advantageously supplied through the cutting punch.

[0023] It is preferred that the compressed air passing through the cutting punch exits through one or more outlet openings on the side of the cutting punch facing the lid blank or the punching slug. This allows the punching slug to be exposed to the air directly on its side facing the cutting punch and thus reliably guided away from it.

[0024] Advantageously, the compressed air passing through the cutting punch is directed to the side of the cutting punch facing the lid blank or the punching slug through several identical outlet openings, which are spaced identically apart. This configuration of the outlet openings effectively prevents the punching slug from becoming skewed or jammed in the die.

[0025] Furthermore, in embodiments of the method in which the compressed air passed through the cutting punch is discharged via one or more outlet openings on the side of the cutting punch facing the lid blank or the punching slug, it is preferred that this compressed air, which is used to convey the punching slug to the conveyor device, be provided intermittently. This is advantageously done in such a way that no compressed air is provided when the tool is open and compressed air is provided when the tool is closed. This simplifies the process and allows energy savings compared to a continuous supply.

[0026] It is further preferred that the outlet openings are only pressurized with compressed air starting with the start of the punching process or, even more preferably, only after the punching process has been completed, preferably when the end point of movement of the cutting punch is reached, which in the case of upwardly moving cutting punches is the top dead center of the movement of the cutting punch.

[0027] In the latter case, the punching slug is completely separated from the lid blank before compressed air is applied, which has the advantage of enabling a cleanly controllable process flow.

[0028] In a first preferred variant of the method according to the invention, the collar, which is formed from the edge of the removal opening by pulling, is rolled towards the removal opening, into a C-curl or a retort curl.

[0029] In a second preferred variant of the method according to the invention, the collar, which is formed from the edge of the removal opening by pulling, is rolled away from the removal opening into a reverse C-curl or a reverse retort curl. In this second variant, the advantages of the invention are particularly evident.

[0030] Furthermore, in the method according to the invention, it is preferred that the cutting punch is moved during punching and the die is stationary, that the cutting punch penetrates the die from bottom to top during cutting, and / or that the lid ring is turned between rolling up the collar and sealing or gluing the tear-off film. This makes it possible to use currently known and established production systems with minor modifications to the punching station to carry out the method. A corresponding punching station according to the invention is the subject of the third aspect of the invention, which will be explained later.

[0031] Preferably, after punching, the cover ring is conveyed out of the cutting tool in a first transport direction, and the punching slug is removed from the tool area by the conveyor in a second transport direction, which runs transversely to the first transport direction, in particular perpendicular to the first transport direction. This offers the advantage that the punching slugs can be transported directly to the area upstream or downstream of the production system by the conveyor.

[0032] A second, unclaimed aspect of the invention relates to a device for producing tear-open lids, in which a tear-open film is sealed or glued to the upper side of the lid on a sealing surface arranged around a removal opening. The device is preferably designed for producing tear-open lids according to the method according to the first aspect of the invention.

[0033] The device comprises a first conveyor for lid blanks, lid rings, and tear-off lids, as well as processing stations, which are provided in succession in the conveying direction for processing the lid blanks, lid rings, and tear-off lids. A first processing station is designed as a punching station for forming a lid ring with a central removal opening surrounded by a sealing flange from a lid blank by punching the same with a punching tool comprising a die and a cutting punch. A second processing station of the device is designed to form a collar projecting from the lid ring, a third processing station for rolling the collar into a curl, and a fourth processing station for sealing or adhering a tear-off film to the sealing flange. Such a device was initially described based on the Figures 1 to 6 described.

[0034] According to the invention, the first processing station is designed such that during punching, the die is arranged on the side that forms the inside of the lid during the later intended use of the lid to be produced (intended inside of the lid), and the cutting punch is inserted into the die from the other side, i.e., from the side that forms the outside of the lid during the later intended use of the lid to be produced (intended outside of the lid), thereby punching out a punching slug. Devices are provided for conveying the punching slug through the die by means of compressed air to a second conveyor device assigned to the first processing station, with which the punching slug is removed from the tool area during the intended operation of the device.

[0035] Such devices for the production of tear-off lids have the advantages already mentioned when describing the process and can be created from existing systems with very little effort in terms of plant engineering modification, with the process sequence and plant concept remaining essentially unchanged.

[0036] The second conveyor device is preferably a magnetic conveyor belt or a vacuum conveyor belt with which the punching slugs can be removed from the tool area.

[0037] The cutting punch advantageously has one or more air ducts for transporting the compressed air within it, which is used in normal operation to convey the punching slug by means of compressed air through the die to the second conveying device.

[0038] For this purpose, the cutting punch advantageously has one or more outlet openings for the compressed air on its side facing the lid blank or the punching slug. This allows the punching slug to be pressurized with compressed air directly on its side facing the cutting punch, thus reliably guiding it away from the punch to the second conveyor.

[0039] It is particularly preferred if the cutting punch has several, e.g., three, in particular identical exit openings, which are spaced identically apart. Such a configuration of the exit openings effectively prevents the punching slug from jamming in the die.

[0040] Furthermore, it is preferred that the device has a control device with which, during normal operation, the compressed air used to convey the punching slug to the second conveyor device can be or is provided intermittently, preferably in such a way that no compressed air is provided when the tool is open and compressed air is provided when the tool is closed, particularly upon reaching the end point of the cutting punch's movement. This simplifies process control and saves energy.

[0041] In a first preferred variant of the device according to the invention, the third processing station is designed such that the collar, which is formed from the edge of the removal opening by pulling, is rolled towards the removal opening into a C-curl or a retort curl.

[0042] In a second preferred variant of the device according to the invention, the third processing station is designed such that the collar, which is formed from the edge of the removal opening by pulling, is rolled away from the removal opening into a reverse C-curl or a reverse retort curl. In this second variant, the advantages of the invention are particularly evident.

[0043] Furthermore, it is preferred that the device according to the invention be designed such that the cutting punch is moved during punching and the die is stationary, that the cutting punch penetrates the die from bottom to top during cutting, and / or that the lid ring is turned in a turning station between the rolling of the collar and the sealing or gluing of the tear-off film. This makes it possible to convert currently known and established production systems into a device according to the invention with minimal modification of the punching station. A corresponding punching station according to the invention is the subject of the third aspect of the invention, which will be explained below.

[0044] Preferably, the first conveyor device has a first transport direction, and the second conveyor device has a second transport direction, which runs transversely to the first transport direction, preferably perpendicular to the first transport direction. This provides the advantage that the punching slugs can be transported directly to the area upstream or downstream of the production system by the conveyor device.

[0045] A third unclaimed aspect of the invention relates to a punching station for a device according to the second aspect of the invention, for forming a lid ring with a central removal opening surrounded by a sealing flange from a lid blank by punching.

[0046] The punching processing station comprises a punching tool with a fixed die and a cutting punch which, during normal punching operation, works against the die from below and moves into the die while punching out a punching lump.

[0047] In addition, it includes devices for conveying the punching slug during normal punching operation by means of compressed air against gravity through the die to a conveyor device assigned to the punching processing station for removing the punching slug from the tool area.

[0048] With such punching processing stations, today's known and established production systems as described above can be converted into inventive devices according to the second aspect of the invention.

[0049] A fourth, unclaimed aspect of the invention relates to a tear-off lid produced or producible by the method according to the first aspect of the invention. Such tear-off lids represent a significant commercial form of the invention. Short description of the drawings

[0050] Further embodiments, advantages, and applications of the invention will become apparent from the dependent claims and the following description with reference to the figures. These show: Fig. 1 a vertical section through a lid blank 9; the Figures 2 to 4 Vertical sections through a cover ring 8 at different stages of production; Fig. 5 a vertical section through a finished tear-off lid 27; Fig. 6 a schematic side view of a device according to the prior art for producing tear-off lids or for carrying out the steps according to the Figures 1 to 5 ; the Figures 7a to 7eVertical sections transverse to the lid transport direction A through the processing tool of the punching processing station 14 from Fig. 6 in different advanced tool positions during the machining of a lid blank according to the state of the art; and the Figures 8a to 8e Vertical sections transverse to the lid transport direction A through the processing tool of the punching processing station in a device according to the invention in differently advanced tool positions during the processing of a lid blank according to the invention. Ways to implement the invention

[0051] To begin with, with reference to the Figures 1 to 6 The prior art production of tear-off lids 27, known to those skilled in the art, has been explained. Reference is made to this explanation here to avoid repetition.

[0052] The procedure according to the invention is described below, with reference to the known device and the known manufacturing steps explained above being made where necessary. In particular, the device and method according to the invention also follow the procedure already known to those skilled in the art for forming the lid ring 8 from the lid blank 9 and for sealing the tear-off film 24.

[0053] The Figures 7a to 7e show the processing tool of the punching processing station 14 from Fig. 6 in tool positions at different stages of advancement during the machining of a lid blank 9 according to the state of the art.

[0054] As can be seen, the tool comprises an upper tool part 1, with a cutting punch 2,3 comprising a cutting ring 2 and a cutting ring carrier 3 and with a clamping ring 4, and a lower tool part 5, with a die 6 and a die carrier 7.

[0055] The upper tool part 1 with the cutting punch 2, 3 is stationary and the lower tool part 5 with the die 6 works against the upper tool part 1.

[0056] In the Fig. 7a In the tool position shown, the tool is open and there is no cover blank 9 in the opened tool.

[0057] Starting from this situation, a cover blank 9 is introduced into the tool in a horizontal direction using the conveyor device 13 (see Fig. 7b ) in such a way that the side forming the outer side of the lid during the later intended use of the lid to be produced (intended outer side of the lid) faces downwards.

[0058] The lower tool part 5 is then moved upwards until the cover blank 9 is clamped between the clamping ring 4 and the die carrier 7 (see Fig. 7c ).

[0059] During the subsequent upward movement of the lower tool part 5, the clamping ring 4 is moved upwards against the force of compression springs 29, which are arranged in the upper tool part 1, and the cutting punch 2, 3 penetrates into the die 6 (see Fig. 7d ). In doing so, it punches out a slug 16 downwards from the lid blank 9, which is discharged via a discharge opening 30 in the base frame 31 of the punching station 14 by gravity conveyance (see Figures 7d and 7e ).

[0060] If the die 6 has reached its end point of movement relative to the cutting punch 2, 3, as shown in Fig. 7e shown, the lower tool part 5 moves back into the Fig. 7a shown lower position and the cover ring 8 obtained by punching is transported by the conveyor device 13 to the next processing station 19.

[0061] The Figures 8a to 8eshow vertical sections transverse to the lid transport direction A through the processing tool of the punching processing station in a device according to the invention in different advanced tool positions during the processing of a lid blank 9 according to the invention. This device differs only in the punching processing station from the device in Fig. 6 shown device according to the state of the art.

[0062] As can be seen, the tool here also comprises a fixed upper tool part 1 and a lower tool part 5 working against the upper tool part. In contrast to the punching processing station 14 according to the Figures 7a-7eHowever, here the upper tool part 1 has a die 6 and a die carrier 7, which forms a space 32 above the die 6, into which a vacuum or magnetic conveyor belt 33 projects horizontally in such a way that it essentially completely spans the upwardly facing opening of the die 6.

[0063] The lower tool part 5 has a cutting punch 2, 3 comprising a cutting ring 2 and a cutting ring carrier 3, as well as a clamping ring 4. As can be seen, the cutting ring carrier 3 has internal air channels 34, which open into several outlet openings 35 arranged on the upper side of the cutting punch 2, 3.

[0064] In the Fig. 8a In the tool position shown, the tool is open and there is no cover blank 9 in the opened tool.

[0065] Starting from this situation, a cover blank 9 is introduced into the tool in a horizontal direction using the conveyor device 13 (see Fig. 8b ) in such a way that the side forming the outer side of the lid during the later intended use of the lid to be produced (intended outer side of the lid) faces downwards.

[0066] The lower tool part 5 is then moved upwards until the cover blank 9 is clamped between the clamping ring 4 and the die 6 (see Fig. 8c ).

[0067] During the subsequent upward movement of the lower tool part 5, the cutting punch 2 moves out of the clamping ring 4, which rests against the die 6 with the clamped cover blank 9, and penetrates into the die 6. In doing so, it punches out a slug 16 from the cover blank 9 (see Fig. 8d ).

[0068] As soon as the cutting punch 2 has reached its end point of movement relative to the die 6, ie it is at the top dead center of its movement, as in Fig. 8e As shown, the air channels 34 in the cutting punch 2, 3 are briefly pressurized with compressed air. As a result, the punching slug 16 is guided through the die 6 against the vacuum or magnetic conveyor belt 33 and is then removed from the tool area in a direction B, which runs transversely to the lid conveying direction A (see Fig. 8e ).

[0069] The lower part of the tool then moves back into the Fig. 8a shown lower position and the cover ring 8 obtained by punching is transported by the conveyor device 13 to the next processing station 19.

[0070] While preferred embodiments of the invention are described in this application, it is to be clearly understood that the invention is not limited thereto and may be embodied in other ways within the scope of the following claims.

Claims

1. Method for manufacturing a tear-open lid (27), wherein a lid ring (8) with a central removal opening (17) surrounded by a sealing flange (18) is formed from a lid blank (9) by punching with a punching tool (1, 5) comprising a die (6) and a cutting punch (2, 3); wherein the edge of the removal opening (17) is formed by drawing to form a collar (20) which projects away from the sealing flange (18) on the intended inside of the cover; wherein the collar (20) is rolled up at its free end; and wherein a tear-open film (24) is sealed or glued onto the sealing flange (18) on the intended outer side of the lid; characterized in that in the punching operation, the die (6) is arranged on the intended inside of the cover and the cutting punch (2, 3) is moved into the die (6) from the intended outside of the cover, while punching a punching lot (16), and in that the punching lot (16) is conveyed by means of compressed air through the die (6) to a conveying device (33), by means of which it is removed from the tool area.

2. Method according to claim 1, characterized in that the lid blank (9) consists of a ferromagnetic material and the conveying device is a magnetic conveyor belt (33).

3. Method according to claim 1, characterized in that the lid blank (9) consists of a ferromagnetic or a non-ferromagnetic material and the conveying device is a vacuum conveyor belt (33).

4. Method according to one of the preceding claims, characterized in that the compressed air used to convey the punching lot (16) to the conveying device (33) is supplied through the cutting punch (2, 3).

5. Method according to claim 4, characterized in that the compressed air that is passed through the cutting punch (2, 3) is made to exit, on that side of the cutting punch (2, 3) that faces the lid blank (9) or the punching lot (16), via one or more outlet openings (35), in particular via a plurality of outlet openings (35) which are at identical distances from one another.

6. Method according to claim 5, characterized in that the compressed air used to convey the punching lot (16) to the conveying device (33) is provided intermittently, in particular in such a way that no compressed air is provided when the tool (1, 5) is open and compressed air is provided when the tool (1, 5) is closed, in particular as a brief pressure surge.

7. Method according to claim 6, characterized in that the outlet openings (35) are not subjected to compressed air until the start of the punching operation or only after punching has been completed, in particular not until the cutting punch (2, 3) has reached the end point of its movement.

8. Method according to one of the preceding claims, characterized in that the collar (20) is rolled towards the removal opening (17), to form a C-curl or a Retort-curl.

9. Method according to one of claims 1 to 7, characterized in that the collar (20) is rolled away from the removal opening (17), to form a reverse C-curl or a reverse retort curl.

10. Method according to one of the preceding claim, characterized in that the cutting punch (2, 3) is moved and the die (6) is stationary during punching.

11. Method according to one of the preceding claim, characterized in that the cutting punch (2, 3) penetrates the die (6) from bottom to top during cutting.

12. Method according to one of the preceding claims, characterized in that the cover ring (8) is turned between the curling of the collar (20) and the sealing or gluing on of the tear-open film (24).

13. Method according to one of the preceding claims, characterized in that after the punching operation the lid ring (8) is conveyed out of the cutting tool (1, 5) in a first transport direction (A) and the punching lot (16) is removed from the tool area by the conveying device (33) in a second transport direction (B) which extends transversely to the first transport direction (A), in particular perpendicularly to the first transport direction.