TWI859648B - Can end and method of manufacturing a can end - Google Patents

Abstract

A can end comprises a metallic end surface in which an opening is formed that is bounded by a closed margin of the end surface and that is closed by a closure piece of the metallic end surface, wherein the closure piece is separated from the surrounding end surface by a microgap extending at least sectionally along the margin of the end surface. A first end region of the closure piece is connected to the surrounding end surface via a pivot bearing. The can end further comprises a tear-open member that engages at a second end region of the closure piece, said second region being opposite the pivot bearing, so that a pivoting of the closure piece out of the plane defined by the opening is made possible by pulling at the tear-open member. The microgap is interrupted between the first end region and the second end region by at least one holding web via which the closure piece and the surrounding end surface are connected to one another in a bonded manner.

Description

Can lid and its manufacturing method

The present invention relates to a can lid, in particular a can lid for beverage cans, comprising: a metal lid surface, in which an opening is formed, the opening is defined by a closing boundary of the lid surface and is closed by a closure member of the metal lid surface, wherein the closure member is separated from the surrounding lid surface by a micro-gap extending at least partially along the boundary of the lid surface, wherein a first lid region of the closure member is connected to the surrounding lid surface through a pivot bearing; and a tearing member, which is engaged with a second lid region of the closure member, the second lid region being opposite to the pivot bearing, so that the closure member can be pivoted away from the plane defined by the opening by pulling the tearing member.

This type of can lid is widely used in the production of beverage cans, food cans, etc. It is simple and inexpensive to produce, can save space for stacking similar cans, can be easily opened, and can be closed again by manually moving the closure if necessary. Due to the micro-gap, no metal particles harmful to health will enter the interior of the can when the can is opened.

When opening a can of beverages, for example, splashing, foaming and/or even popping may occur, especially when the can contains carbonated beverages. To avoid this, some users try to tap the can wall before opening or pull the tear member as slowly and carefully as possible. However, such measures are cumbersome and have limited effectiveness.

One object of the present invention is to enable such a can lid to be opened more easily and smoothly, in particular to counteract splashing, foaming and/or bursting.

The object is achieved by a can lid having the features of claim 1.

The invention provides that the micro-gap is interrupted between the first cover area and the second cover area by at least one retaining web, through which the closure and the surrounding cover surface are connected to each other in an engaging manner. When the closure is pivoted upward by pulling the tear-off member, initially only a relatively small opening is produced, which starts from the second cover area and extends at most to the retaining web. The retaining web initially blocks the opening from further expansion. Due to this relatively small initial opening, venting of the can has already occurred, which is also called "venting". During the further opening action, the retaining web tears, so that the closure can be fully unfolded and the entire opening is thus released. Since venting has already taken place, no noticeable splashing or blistering occurs. For the user, the pre-venting before full opening may not even be noticeable in some cases. A particular advantage is that the simple design of the can lid according to the invention is provided with a recess for forming a retaining web, since the micro-gap is not designed to completely surround the outer periphery. It is therefore not necessary to provide an additional retaining device.

Another advantageous effect of the invention is that the retaining web increases the stability of the lid closure. This means that, due to the metal retaining web, the closure does not leak or even break even at significantly increased internal pressures in the can and/or at high temperatures. High temperatures and the associated high internal pressures occur not only in the case of solar radiation of cans containing carbonated beverages, but also in the case of pasteurization, which is mandatory for many applications. Therefore, a sealing membrane can be provided for covering micro-gaps, which can be protected from overloading by the retaining web.

Furthermore, the advantage of the retaining web is that it ensures that the closure is securely held in the opening during the production process.

According to an embodiment of the present invention, the width of at least one retaining web is 0.1 mm to 6 mm, and preferably 1.5 mm to 4 mm. It can be seen that with such a web width, on the one hand, a sufficiently strong retaining effect can be ensured to achieve a venting effect, and on the other hand, the retaining web is sufficiently easy to break to avoid damage during the opening process. The width of the retaining web can be measured along the edge defining the opening or along the route of the micro-gap.

At least one retaining web may have a notch. During the first upward pivoting of the closure, the notch ensures that the tearing of the retaining web is limited, in other words the retaining web tears along the notch. Undesired tearing of the closure or the surrounding cover surface is thus avoided. The notch may extend along the cover surface and/or the border of the micro-gap. The shape and depth of the notch may be adjusted to produce the desired tearing force. The notch preferably has a depth of at least 0.03 mm and/or a depth of at least one quarter of the thickness of the metal cover surface.

The micro-gap region is preferably interrupted between the first cover region and the second cover by a web arrangement comprising at least two retaining webs, via which the closure and the surrounding cover surface are connected to each other in an engaging manner. This ensures that the closure is evenly fixed in the opening. The web arrangement can be designed so that a relatively small initial opening is formed during the opening process. The smaller the initial opening, the more controlled and smoother the escape of excess pressure can be.

The web arrangement may include retaining webs arranged on both sides of the second cover region. Thus, the separation of the micro-gap is opposite on both sides of the joint of the tear-away member, so that the retaining effect is uniform and consistent.

The web arrangement preferably comprises at least one pair of retaining webs arranged opposite each other relative to a central region of the closure. This provides symmetrical resistance to the opening action.

The web arrangement can include at least four and at most eight retaining webs, preferably six retaining webs, which are arranged distributed along the borders of the cover surface. This allows the closure to be held particularly stably in the opening and counteracts overloading of the coating or film covering the micro-gaps.

The retaining webs of the web configuration can be designed to be identical, ensuring a particularly simple design.

Another embodiment of the invention provides that the micro-gap is a stamped gap and that at least one retaining web is formed by a stamped recess. This allows particularly simple and cost-effective production. In the stamped recess, an embossing device, such as an embossing stamp, can be arranged, which is arranged to produce a recess in the corresponding retaining web, in particular a recess as described above.

According to a specific embodiment, the micro-gap has a maximum width of 0.01 mm. This has proven to be particularly advantageous in practical applications. The closure can also be held on the surrounding cover surface by clamping.

The coating composed of plastic material can be applied to the plane side of the metal cover surface in a manner covering the micro-gaps. The sealing of the can cover can be ensured by the coating covering the micro-gaps despite the lack of a continuous metal connection between the closure and the surrounding cover surface. When the closure moves out of the plane defined by the opening, the coating composed of plastic material tears in the area of the micro-gaps, making the subsequent opening unrestricted.

The coating is preferably applied on the inner side of the metal cover surface. Therefore, the coating is preferably applied on the cover side facing the inside of the can. Generally speaking, the inner side of the metal cover surface is the lower side of the metal cover surface.

The coating can be applied to the entire area of the flat side of the metal cover surface. This is advantageous in terms of technical production and ensures a particularly strong sealing effect. The coating can be designed as a film and/or can be applied to the metal cover surface in a firmly attached manner, for example sealed to the metal cover surface. The plastic material can be polypropylene, which is suitable for food.

According to another embodiment of the invention, the coating has a weakened portion, in particular a regionally reduced material thickness, which is configured to be spaced apart from the micro-gap. The weakened portion can be generated during the sealing process of applying the coating. In general, a notch or an at least partially open notch can be provided as a weakened portion, such as a perforation. The weakened portion reduces the force required to open the can. Due to the distance between the weakened portion and the micro-gap, a high seal can be ensured.

The tear-off member can be a gripping, pulling and/or levering element, in particular it is made of a plastic material. The user can move the gripping, pulling and/or levering element, thereby causing the closure to pivot upwards about a pivot bearing axis defined by the pivot bearing. In particular, a two-arm lever member made of a plastic material can be provided, which is fixedly connected to the metal cover surface. The gripping, pulling and/or levering element preferably has an annular gripping portion, for example an annular pull ring (ring tab). The ring-shaped pull-tab is particularly advantageous in practical operation, since it can be easily grasped and enables the relatively comfortable opening of the can, which is performed by a pulling motion.

Another embodiment of the invention provides that a sealing frame made of plastic material and surrounding the opening is connected to the surrounding cover surface, and a closure unit made of plastic material and supporting the closure is pivotally attached to the surrounding cover surface, wherein the sealing frame and the closure unit are releasably connected to each other in a fluid-tight manner through sealing and latching ribs and associated receiving grooves. Such a can lid has a reclosable opening. The sealing and latching ribs and the receiving groove are preferably designed so that full reclosing can be felt by a snap-in connection and, if desired, can be sensed audibly. Unlike so-called standard can lids which are not reclosable, the closure of a reclosable can lid cannot be deformed to a sufficient degree to allow for venting of gas by deformation. Therefore, the present invention is particularly applicable to reclosable can lids, but the invention is not limited thereto.

The invention also relates to a method for producing a can lid, in particular a can lid for beverage cans, preferably a can lid as claimed in any of the preceding claims, wherein a metal element is provided at least partially and wherein a closure is stamped out of the metal element and reinserted into an opening formed by the stamping process.

According to the invention, the stamping is performed by means of a stamping die having a cutting edge, and the cutting edge has at least one recess. This enables the retaining web to be provided in a particularly simple manner in the form of a joint connection between the closure and the surrounding cover surface.

The present invention also relates to a can lid, in particular a can lid for beverage cans, comprising: a metal lid surface, in which an opening is formed, the opening is defined by a closing boundary of the lid surface and is closed by a closing piece of the metal lid surface, wherein the closing piece is separated from the surrounding lid surface by a micro gap extending at least partially along the boundary of the lid surface, in particular a can lid as described above.

According to the present invention, the exhaust notch is formed on the surface of the metal cover and connected to the micro gap.

When the sealing film is laid on the surface of the metal cover, the venting recess ensures the venting through the micro-gap and thus counteracts the undesired formation of bubbles between the sealing film and the metal cover surface. The venting recess can be embossed onto the surface of the metal cover. According to an embodiment of the invention, the venting recess has a V-shaped cross-section and/or a depth of 0.005 mm to 0.2 mm, preferably 0.03 mm to 0.1 mm.

The configuration of the venting recess is preferably formed on the inner side of the metal cover surface, and in particular, the coating layer composed of the plastic material is laid on the inner side of the metal cover surface in a manner that covers the micro gap and at least partially covers the configuration of the venting recess.

It can be provided that the venting recesses define a radial pattern and/or each of the venting recesses extends at least from the micro-gap to the boundary area of the metal cover surface. This enables effective venting over the entire film surface or cover surface.

Further developments of the invention can also be seen from the dependent claims, the following description and the attached drawings.

11: Can lid

12: Beaded edge

13: Metal cover surface, cover surface

15: Reclosable opening system

19: Closed piece

21: Micro gap

23: Surrounding cover surface

25: Outer Boundary

27: Inner boundary, boundary, boundary area

40: Closed unit

47: Tear off the components

48: Pivot bearing

61: First cover area

62: Second cover area

65: Keep the belly plate

66: Central area

70,70': Web configuration

72: Line

75: Notch

80: Exhaust notch

87:Border area

The present invention will be described below by way of example with reference to the drawings.

FIG. 1 is a plan view of a can lid for beverage cans according to the present invention, wherein the can lid includes a reclosable opening system;

Figure 2 shows the can lid according to Figure 1, with the opening system omitted;

FIG3 is a partial enlarged view of the can lid shown in FIG2, which shows the retaining web;

FIG. 4 shows a can lid according to another embodiment of the present invention; and

FIG. 5 shows in simplified form the lower side of the can lid according to the present invention.

FIG. 1 shows a can lid 11, which is particularly used for canned beverages and has a reclosable opening system 15 integrated in its metal lid surface 13. The can lid 11 can be connected to an associated container (not shown) via a beaded rim 12. The opening is arranged in the metal lid surface 13, and in the transport state of the can lid 11 shown in FIG. 1, the opening arranged in the metal lid surface 13 is closed by a part of the metal lid surface 13 in the form of a closure 19.

As shown in FIG. 2 , the closure member 19 is separated from the surrounding cover surface 23 by a micro gap 21. In the area of the micro gap 21, the outer boundary 25 of the closure member 19 and the inner boundary 27 of the surrounding cover surface 23 are adjacent to each other.

The metal cover surface 13 is preferably formed by a sheet metal layer consisting of aluminum or tin plate. A coating consisting of a plastic material and covering the micro gap 21 is applied on the inner plane side of the metal cover surface 13, but this cannot be observed in Figures 1 and 2. An adhesive lacquer layer, which is also not observed in the figures, can be provided for the fixed connection of the coating to the metal cover surface 13. The coating is preferably applied over the entire area of the inner plane side of the metal cover surface 13. However, in some applications, it may be sufficient to provide the coating only in the environment of the micro gap 21. The coating may be a plastic film, for example, made of propylene. Notches extending along the micro gap 21 at predetermined intervals are formed in the coating.

The can lid 11 can be opened by moving the closure 19 out of the plane defined by the opening (the paper plane in FIGS. 1 and 2 ). Since there is no joint connection between the closure 19 and the surrounding lid surface 23 in the area of the micro-gap 21 , according to the invention, no significant metal separation occurs at the first opening of the can provided with the can lid 11 , thereby reducing or completely preventing the formation of metal particles which would otherwise be difficult to avoid. Avoiding the generation of particles during the opening process, in particular particles consisting of aluminum, is important in terms of health, since such particles also inevitably enter the product contained in the corresponding can and therefore also the human body.

The coating reliably seals the micro-gap 21. The notch can have a uniform depth or, if applicable, can have locally different depths, which ensures that relatively little force is required to open the can lid 11. The distance between the micro-gap 21 and the notch 75 is preferably about 0.2 to 0.5 mm in total, which improves the sealing effect.

The reclosable opening system 15 (FIG. 1) comprises a sealing frame, not recognizable in the plan view according to FIG. 1, which is made of plastic material and surrounds the opening, said sealing frame being fixedly connected to the surrounding lid surface 23. A closing unit 40 is also provided which is made of plastic material and supports the closing piece 19 and is pivotably attached to the surrounding lid surface 23. A releasable fluid-tight connection can be formed between the sealing frame and the closing unit 40 by means of a latching device formed by sealing and latching ribs 43 and associated receiving grooves. The can lid 11 is thus reclosable.

A tear-off member 47, which is here annular and preferably also made of plastic, is connected to or directly molded on the closure unit 40 and is correspondingly fixed to the closure 19. By pulling the tear-off member 47, the user can pivot the closure 19 upward out of the plane defined by the opening and can thereby release the opening while separating the coating. A molded pivot bearing 48 (FIG. 1) is formed on the closure unit 40 in a manner arranged radially opposite to the closure unit 40 and is fixedly connected to the surrounding cover surface 23. Thus, the first cover region 61 of the closure 19 is connected to the surrounding cover surface 23 via the pivot bearing 48, while the tear-off member 47 is engaged with the second cover region 62 of the closure 19, which is opposite to the pivot bearing 48.

Between the first cover area 61 and the second cover area 62, the microgap 21 is interrupted by two retaining webs 65 (FIG. 2), through which the closure 19 and the surrounding cover surface 23 are connected to each other in an engaged manner. The two retaining webs 65 form a web arrangement 70. As shown, the two retaining webs 65 are arranged opposite each other relative to the central area 66 of the closure 19. The width of the retaining webs 65 of the same design is preferably in the range of 0.5 mm to 6 mm and, for example, totals at least about 3 mm. Depending on the application, more than two retaining webs 65 can also be provided. A detailed schematic diagram of one of the retaining webs 65 is shown in FIG. 3, wherein the microgap 21 is represented here with an exaggerated width for the sake of clarity.

The retaining web 65 preferably has corresponding notches 75 to avoid unrestrained tearing of the metal cover material.

When opening the can for the first time, the user pulls the tear member 47 and thereby pivots the closure unit 40 with the closure 19 upward. As a result, the latching connection between the closure unit 40 and the sealing frame is released. In addition, the coating separates along the micro-gap 21.

Due to the retaining web 65, at the beginning of the pivoting process, only a relatively small opening is produced in the lid surface 13, which extends from the second lid region 62 to the region of the retaining web 65. The retaining web 65 at least temporarily blocks a further enlargement of the opening. The relatively small opening in the environment of the second lid region 62 provides for venting of the can. During the further pivoting process, the retaining web 65 tears, in particular due to its relatively narrow design. After the retaining web 65 has torn, the closure 19 can be pivoted completely upwards to release the entire opening. Due to the opening formed by the retaining web 65 and the associated venting effect, no noticeable splashing, bursting or blistering occurs.

The contents of the can can be taken out through the resulting opening. When the closing unit 40 with the closing piece 19 is pivoted back again, the latching connection between the closing unit 40 and the sealing frame can be reestablished despite the coating being separated, so that the opening is tightly sealed again. Opening and closing can be repeated as needed.

In an alternative embodiment of the can lid 11 according to the invention shown in FIG. 4 , a web arrangement 70 ′ is provided comprising a total of six retaining webs 65 which are arranged distributed along the border 27 of the metal lid surface 13 . Specifically, three retaining webs 65 are arranged on each side of a line 72 extending through the first lid region 61 and the second lid region 62 . In this way, on the one hand, a more finely graded venting can be achieved and, on the other hand, it is ensured that the closure 19 is particularly stably held in the intended position before the closure is initially opened. It should be understood that the number, distribution and width of the retaining webs 65 may vary depending on the individual application.

Fig. 5 shows a can lid 11 according to the present invention from below in a simplified form. The configuration of the venting recess 80 is formed on the lower side, that is, the inner side, of the metal cover surface 13. As shown in the figure, each venting recess 80, especially the straight venting recess, extends from the boundary area 87 of the metal cover surface 13 to the micro gap 21. The venting recess 80 can also extend slightly beyond the boundary area 27. The direction of the venting recess 80 is radial. In the embodiment shown, the venting recess 80 defines a radial pattern, that is, the venting recess 80 extending radially is configured to be distributed on the periphery of the metal cover surface 13 which is circular in this example. The venting recess 80 is preferably embossed into the metal cover surface 13 by an embossing tool, for example with an embossing depth of 0.07 mm.

The arrangement of the micro-gap 21 and the venting recess 80 is covered by a sealing film which cannot be observed in FIG. 5 and which is made of plastic and is laid on the inner side of the metal cover surface 13. In particular, when the sealing film is laid, the venting recess 80 vents the intermediate space between the metal cover surface and the sealing film through the micro-gap 21. The micro-gap 21 is thus used for venting. In this way, the formation of bubbles and the like is prevented and actually spans the entire metal cover surface 13 due to the radial pattern.

The function of the retaining web 65 is independent of the presence of the reclosable opening system 15. The described arrangement of one or more retaining webs 65 is therefore also advantageous for non-reclosable can lids without sealing frame and closure unit (i.e. for standard can lids).

Furthermore, the effect of the venting recess 80 is independent of the presence of the retaining web 65, so the provision of the venting recess 80 is also advantageous for standard can lids and reclosable can lids where the micro-gap is not interrupted by the retaining web.

To produce the can lid 11 according to the invention, an areal metal element, such as a sheet metal layer consisting of aluminum or tin plate, is provided and fed into an embossing device, where the beaded edge 12, the venting recess 80 and the grooves, reinforcement beads, etc. are formed into the areal metal element. The stamped metal element is fed into a stamping device, where the closure 19 is stamped out of the metal element and reinserted into the opening formed by the stamping process. Specifically, during the return stroke of the stamping die, the stamped closure 19 is immediately pressed directly into the sheet metal layer again by the spring force and is held there in a force-fitted manner.

To produce the retaining web 65, stamping is performed by means of a stamping die, the cutting edge of which is not designed with a closed perimeter, but has a corresponding recess with a corresponding embossing die for producing the recess 75. A coating, in particular a sealing film, is then applied to the inner planar side of the metal element. The embossing device and the stamping device can be integrated into a progressive tool, if necessary together with other processing equipment.

11: Can lid

13: Metal cover surface, cover surface

19: Closed piece

21: Micro gap

23: Surrounding cover surface

25: Outer Boundary

27: Inner boundary, boundary, boundary area

61: First cover area

62: Second cover area

65: Keep the belly plate

66: Central area

70: Web configuration

Claims (20)

A can lid (11), in particular a can lid for a beverage can, comprising: a metal lid surface (13) in which an opening is formed, the opening being defined by a closing boundary (27) of the lid surface (13) and closed by a closure member (19) of the metal lid surface (13), wherein the closure member (19) is separated from a surrounding lid surface (23) by a micro gap (21) extending at least partially along the boundary (27) of the lid surface (13), wherein a first lid region (61) of the closure member (19) is connected to the surrounding lid surface (23) via a pivot bearing (48); and A tear-off member (47) is engaged with a second cover region (62) of the closure member (19), the second cover region (62) being opposite to the pivot bearing (48), so that by pulling the tear-off member (47), the closure member (19) can be pivoted away from the plane defined by the opening, wherein the micro-gap (21) is interrupted between the first cover region (61) and the second cover region (62) by at least one retaining web (65), and through the at least one retaining web (65), the closure member (19) and the surrounding cover surface (23) are connected to each other in an engaged manner. The can lid as described in claim 1 is characterized in that the width of the at least one retaining web (65) is 0.5 mm to 6 mm, and preferably 1.5 mm to 4 mm. The can lid as claimed in claim 1 or 2 is characterized in that at least one retaining web (65) has a notch (75). The can lid as claimed in claim 1 or 2 is characterized in that the micro gap (21) is interrupted between the first lid region (61) and the second lid region (62) by a web arrangement (70, 70'), the web arrangement (70, 70') comprising at least two retaining webs (65), through which the closure member (19) and the surrounding lid surface (23) are connected to each other in an engaging manner. The can lid as described in claim 4 is characterized in that the web arrangement (70, 70') includes retaining webs (65) arranged on both sides of the second lid area (62). The can lid as claimed in claim 5 is characterized in that the web arrangement (70, 70') comprises at least one pair of retaining webs (65), and the at least one pair of retaining webs (65) are arranged opposite to each other relative to the central area (66) of the closure (19). The can lid as claimed in claim 4 is characterized in that the web arrangement (70') comprises at least four and at most eight retaining webs (65), preferably six retaining webs (65), which are distributed along the boundary (27) of the lid surface (13). A can lid as claimed in claim 4, characterized in that the retaining webs (65) of the web arrangement (70, 70') have the same design. The can lid as described in claim 1 or 2 is characterized in that the micro gap (21) is a stamped gap, and the at least one retaining web (65) is formed by a stamped recess. The can lid as described in claim 1 or 2 is characterized in that the maximum width of the micro gap (21) is 0.01 mm. The can lid as described in claim 1 or 2 is characterized in that a coating layer made of plastic material is applied on the plane side of the metal lid surface (13) in a manner covering the micro gap (21). The can lid as described in claim 11 is characterized in that the coating is applied on the inner side of the metal lid surface (13). The can lid as described in claim 11 is characterized in that the coating is applied over the entire area of the planar side of the metal lid surface (13). The can lid as described in claim 11 is characterized in that the coating has a weakened portion disposed at a certain distance from the micro gap (21). A can lid as claimed in claim 1 or 2, characterized in that the tearing member (47) is a gripping, pulling and/or levering element, in particular it is made of plastic material. A can lid as claimed in claim 1 or 2, characterized in that a sealing frame made of plastic material and surrounding the opening is connected to the surrounding lid surface (23), and a closing unit (40) made of plastic material and supporting the closure (19) is pivotally attached to the surrounding lid surface (23), wherein the sealing frame and the closing unit (40) are releasably connected to each other in a fluid-tight manner through sealing and latching ribs and associated receiving grooves. A method for producing a can lid (11), in particular a can lid for a beverage can, preferably a can lid as claimed in any one of claims 1 to 16, wherein a metal element of at least a local area is provided, and wherein a closure (19) is stamped out of the metal element and reinserted into the opening formed by the stamping process, characterized in that the stamping is performed by a stamping die having a cutting edge, and the cutting edge has at least one recess. A can lid (11), in particular a can lid for beverage cans, comprising: a metal lid surface (13) in which an opening is formed, the opening being defined by a closing boundary (27) of the lid surface (13) and closed by a closing member (19) of the metal lid surface (13), wherein the closing member (19) is separated from the surrounding lid surface (23) by a micro-gap (21) extending at least partially along the boundary (27) of the lid surface (13), in particular a can lid as claimed in any one of claims 1 to 17, characterized in that a venting recess (80) is formed on the metal lid surface (13) and connected to the micro-gap (21). The can lid as described in claim 18 is characterized in that the venting recess (80) is formed on the inner side of the metal lid surface (13), and in particular, a coating layer made of a plastic material is applied on the inner side of the metal lid surface (13) in a manner that covers the micro gap (21) and at least partially covers the venting recess (80). The can lid as claimed in claim 18 or 19 is characterized in that the venting recess (80) defines a radial pattern and/or each of the venting recesses (80) extends at least from the micro-gap (21) to the boundary region (87) of the metal lid surface (13).

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