DE102023109429A1 - can lids - Google Patents

Abstract

A can lid comprises a metallic lid surface with a first flat side and a second flat side facing away from the first flat side, wherein an opening is formed in the lid surface which is delimited by a closed edge of the lid surface and which is closed by a closure piece which is separated from the surrounding lid surface by a micro-gap extending along the edge of the lid surface, wherein a first end region of the closure piece is connected to the surrounding lid surface via a pivot bearing, and with a tear-open element arranged on the first flat side which engages a second end region of the closure piece opposite the pivot bearing, so that the closure piece can be pivoted by pulling on the tear-open element, wherein the micro-gap between the first end region and the second end region is interrupted by at least one retaining web. A pressure relief wave is embossed into the lid surface which extends at least partially around the opening.

Description

The invention relates to a can lid, in particular for beverage cans, with a metallic lid surface which has a first flat side and a second flat side facing away from the first flat side, wherein an opening is formed in the lid surface which is delimited by a closed edge of the lid surface and which is closed by a closure piece of the metallic lid surface, wherein the closure piece is separated from the surrounding lid surface by a micro-gap which extends at least in sections along the edge of the lid surface, wherein a base plane of the closure piece is defined by the course of the micro-gap, wherein a first end region of the closure piece is connected to the surrounding lid surface via a pivot bearing, and with a tear-open element arranged on the first flat side which engages a second end region of the closure piece opposite the pivot bearing, so that by pulling on the tear-open element, the closure piece can be pivoted out of the base plane in the direction of the first flat side, wherein the micro-gap between the first end region and the second end region is interrupted by at least one retaining web, via which the closure piece and the surrounding lid surface are firmly bonded to one another.

Can lids of this type are used extensively in the manufacture of beverage cans, food cans and the like. They are easy and inexpensive to manufacture, enable space-saving stacking of similar cans and can be easily opened and closed again if necessary by manually moving the closure piece. Due to the gradual opening by the retaining bar and the associated ventilation effect (“venting”), there is no significant splashing, banging or foaming when the can is first opened.

In principle, it is desirable that the initial opening of the can requires only a small amount of force. However, this aim is counteracted by the need to ensure that there are no leaks in the area of the opening or that the sealing film on the second flat side does not stretch, even if the pressure inside the can increases. In practice, it is difficult to ensure that the can is easy to open for the first time and that it is sufficiently stable under increased pressure. A particular challenge is the pasteurization process required for many can contents, such as juices, food and the like, which involves a pressure of, for example, 6 bar and can lead to considerable stress on the material.

It is an object of the invention to provide a can lid which is easy to open and yet has a high resistance to pressure increases in the associated can.

The problem is solved on the one hand by a can lid with the features of claim 1.

According to the invention, at least one pressure relief wave is embossed into the metal lid surface, which extends at least partially around the opening. The pressure relief wave ensures mechanical decoupling of the inner region surrounding the opening from the surrounding outer lid surface. If the can lid bulges as a result of a pressure increase in the can or bulges further from a bulged state, the pressure relief wave is pulled apart to a certain extent so that material is discharged inwards. In this way, the connection between the closure piece and the surrounding lid surface and in particular the retaining web is relieved. It has been shown that a can lid provided with a pressure relief wave is on the one hand easy to open and on the other hand reliably withstands relatively high pressure values.

The pressure relief wave can comprise a wave trough with a curved cross-section extending transversely to the base plane. The curved course ensures a flexible coupling to a certain extent between the inner and outer lid areas and thus contributes to stabilizing the closed opening when the can lid bulges.

It can be provided that the pressure relief shaft has a height or depth relative to the base plane that is at least half the thickness of the metal cover surface and at most four times the thickness of the metal cover surface, wherein the height or depth of the pressure relief shaft is preferably at least as great as the thickness of the metal cover surface and at most twice the thickness of the metal cover surface. The thickness of the metal cover surface is to be understood here as a uniform or average thickness. Preferably, the height or depth of the pressure relief shaft is uniform over its longitudinal extent. A height or depth as stated has proven to be particularly advantageous in practice.

According to one embodiment of the invention, the metallic cover surface is rotationally symmetrical and the radial extension of the at least one pressure relief shaft, relative to the rota tion center of the metallic cover surface is at least twice and at most five times the thickness of the metallic cover surface. A pressure relief shaft of corresponding width fulfills the relief function particularly reliably.

Preferably, the at least one pressure relief wave has a circular or circular arc-shaped course within the base plane. This results in a particularly uniform relief effect, in particular with a circular cover surface.

The opening can have a geometric center that coincides with the center of the circular or circular arc-shaped course of the at least one pressure relief shaft. This further promotes a uniform relief effect.

According to a further embodiment of the invention, at least two, preferably at least three and particularly preferably exactly three pressure relief waves are embossed into the metal cover surface, which extend parallel to one another at least partially around the opening. The relief effect is thereby increased. In addition, the presence of several parallel pressure relief waves enables the relief to be graduated in an adapted manner.

Preferably, the height or depth of the pressure relief waves relative to the base level increases towards the opening. The radially innermost pressure relief wave therefore provides the greatest flexibility. Pressure relief graded in this way has proven to be particularly advantageous.

According to a special design, the arc lengths of the pressure relief waves increase towards the opening. In general, the further the pressure relief wave is from the opening, the less expansion potential is required.

It is preferred that the pressure relief shaft closest to the opening has a closed circular course within the base plane and at least one pressure relief shaft further away from the opening has an interrupted circular course. For example, an interruption can be arranged in an area in which the opening is closest to the edge of the cover surface. In this area, there may not be space for another circumferential pressure relief shaft. However, a pressure relief shaft with an interrupted course can already be provided. A particularly preferred embodiment provides one closed inner and two interrupted outer pressure relief shafts.

A special embodiment of the invention provides that the metallic cover surface and the opening have respective geometric centers that are arranged at a distance from one another, wherein the at least one pressure relief shaft that is further away from the opening has an interruption in the circular course through which a connecting line between the two geometric centers runs. For example, the metallic cover surface and the opening can be rotationally symmetrical, in particular circular, and the respective rotation centers form the geometric centers.

The invention also relates to a can lid, in particular for beverage cans, in particular as specified above, with a metallic lid surface which has a first flat side and a second flat side facing away from the first flat side, wherein an opening is formed in the lid surface which is delimited by a closed edge of the lid surface and which is closed by a closure piece of the metallic lid surface, wherein the closure piece is separated from the surrounding lid surface by a micro-gap which extends at least in sections along the edge of the lid surface, wherein a base plane of the closure piece is defined by the course of the micro-gap, wherein a first end region of the closure piece is connected to the surrounding lid surface via a pivot bearing, and with a tear-open element arranged on the first flat side which engages a second end region of the closure piece opposite the pivot bearing, so that by pulling on the tear-open element, the closure piece can be pivoted out of the base plane in the direction of the first flat side, wherein the micro-gap between the first end region and the second end region is interrupted by at least two retaining webs via which the closure piece and the surrounding cover surface are firmly bonded together.

The more and wider the retaining bars are, the more stable the closure piece will be in the opening. However, a stable fit of the closure piece makes initial opening more difficult. As mentioned above, it is challenging to simultaneously ensure easy initial opening and sufficient stability under increased pressure.

To solve this problem, according to one aspect of the invention, an elongated elevation is embossed into the closure piece, which rises above the base plane in the direction of the first flat side and extends transversely to a line which through two of the at least two support bridges and through the elongated elevation.

When the can lid bulges as a result of an increase in pressure in the can, the central area of the closure piece moves upwards first. The elevation has a stiffening effect and, due to its shape and orientation, acts like a lever, ensuring that the upward movement of the central area is accompanied by a downward movement of the edge area. This creates a virtual axis of rotation that runs parallel to or coincides with the connecting line between the two retaining webs. This relieves the transition between the closure piece and the surrounding lid surface and prevents the metal edges from drifting apart undesirably at the micro-gap. It has been shown that, due to the effect of the elongated elevation, it is possible to move the retaining webs further back from the point of attack of the tear-open device than was previously possible. Such a backward offset is particularly advantageous because of the improved "venting" effect.

The elongated elevation can extend from the second end area towards the first end area. This means that the elongated elevation can extend from the point of application of the tear-open device towards the pivot bearing. If the can lid bulges, the area of the tear-open point is then particularly relieved of stress. This is advantageous in that the retaining webs should be as far away from the tear-open point as possible due to the "venting" and this area is therefore particularly susceptible to pressure loads.

A further embodiment of the invention provides that the opening has a geometric center and the elongated elevation has a longitudinal axis that runs through the geometric center of the opening. This ensures a particularly favorable relief effect.

Preferably, the elongated elevation has a height relative to the base plane that is at least as large as the thickness of the metallic cover surface and at most four times the thickness of the metallic cover surface, with the height of the elongated elevation particularly preferably being at least one and a half times the thickness of the metallic cover surface and at most three times the thickness of the metallic cover surface. Such a height has proven to be particularly advantageous in common applications.

It is preferred that the elongated elevation has a length that is at least five times the thickness of the metallic cover surface and at most seventy times the thickness of the metallic cover surface, with the length of the elongated elevation particularly preferably being at least twenty times the thickness of the metallic cover surface and at most fifty times the thickness of the metallic cover surface. Such elevation lengths ensure a particularly good adaptation of the stiffening effect to conventional cover designs.

It can be provided that the opening has a rounded hexagonal shape and the elongated elevation extends from a corner area of the opening towards an opposite corner area of the opening. In particular, the elongated elevation can extend from a corner area that coincides with the second end area. Tearing at the corner enables particularly good ventilation. At the same time, the elevation ensures that the closure piece does not come loose prematurely at the corner. The rounded hexagonal shape of the opening is advantageous in that it is particularly easy to provide the retaining webs on the straight sections.

The elongated elevation can have a club shape. This enables a particularly favorable graduated stiffening effect.

According to a special embodiment, the elongated elevation has a head section close to the edge and a tail section that is narrower than the head section. It has been shown that a particularly pronounced increase in stability is desirable in the area of the edge.

The tail section may be tapered in a direction away from the head section, preferably continuously. The stiffening effect then decreases away from the tear point, which has been found to be particularly advantageous.

The invention further relates to a can lid, in particular for beverage cans, in particular as stated above, with a metallic lid surface which has a first flat side and a second flat side facing away from the first flat side, wherein an opening is formed in the lid surface which is delimited by a closed edge of the lid surface and which is closed by a closure piece of the metallic lid surface, wherein the closure piece is separated from the surrounding lid surface by a micro-gap which extends at least in sections along the edge of the lid surface, wherein a first end region of the closure piece is connected to the surrounding lid surface via a pivot bearing, and with a tear-open member arranged on the first flat side which is attached to a two th end region of the closure piece, so that by pulling on the tear-open member, the closure piece can be pivoted out of the base plane defined by the opening in the direction of the first flat side, wherein the micro-gap between the first end region and the second end region is interrupted by at least one retaining web, via which the closure piece and the surrounding lid surface are materially connected to one another.

To solve the problem mentioned at the outset, according to a further aspect of the invention, a closure relief bead is embossed into the closure piece, which extends along the edge of the opening at least past the at least one retaining web.

In the event of a pressure increase in the can, the retaining bar is decoupled from the central area of the closure piece by the closure relief bead and is thus protected from undesirable overloading. Any expansion of the lid surface is compensated by the closure relief bead so that the retaining bar is not overloaded or even broken.

The closure relief bead can be curved away from the edge in the area of the retaining web. In this design, the closure relief bead shields the retaining web particularly effectively from the central area of the closure piece.

It can be provided that the micro-gap between the first end region and the second end region is interrupted by a plurality of retaining webs, via which the closure piece and the surrounding cover surface are connected to one another in a materially bonded manner, wherein the closure relief bead extends past all retaining webs and is curved away from the edge in the area of each retaining web. All retaining webs are thus protected from overloading.

Preferably, the closure relief bead is curved towards the edge in the area between two consecutive retaining webs. This enables the formation of a closed, circumferential closure relief bead despite the curvatures pointing away from the edge in the area of the retaining webs.

A further embodiment of the invention provides that the closure relief bead has a height or depth relative to the base plane that is at most one and a half times the thickness of the metallic cover surface, wherein the height or depth of the closure relief bead is preferably at most as large as the thickness of the metallic cover surface. This has proven to be particularly advantageous in common cover designs.

Preferably, the closure relief bead has a first flank facing the edge of the lid surface and a second flank facing away from the edge of the lid surface, the second flank being steeper than the first flank. This results in a particularly favorable relief effect.

A combination of a pressure relief shaft as described above with an elongated elevation as described above and/or the closure relief bead has proven to be particularly advantageous. In particular, the relief features mentioned can have a graduated effect. For example, in the case of a moderate increase in pressure, only the pressure relief shaft can initially come into operation and the retaining web can only be protected by the closure relief bead when a higher threshold value is exceeded.

Further developments of the invention can also be found in the dependent claims, the description and the accompanying drawings.

• 1 ist eine Draufsicht auf einen erfindungsgemäßen Dosendeckel in einem verschlossenen Zustand.
• 2 zeigt den Dosendeckel gemäß 1 ohne Verschlussbauteile.
• 3 zeigt ein Verschlussstück des Dosendeckels gemäß 2 in Einzeldarstellung.
• 4 zeigt einen Querschnitt durch das Verschlussstück der 3 entlang der Linie A-A.
• 5 zeigt eine Anordnung von Druckentlastungswellen des Dosendeckels gemäß 1 in einer Querschnittsansicht.

The invention is described below by way of example with reference to the drawings.

• 1 is a plan view of a can lid according to the invention in a closed state.
• 2 shows the can lid according to 1 without locking components.
• 3 shows a closure piece of the can lid according to 2 in individual presentation.
• 4 shows a cross section through the closure piece of the 3 along line AA.
• 5 shows an arrangement of pressure relief shafts of the can lid according to 1 in a cross-sectional view.

1 and 2 show a can lid 11 designed according to the invention for a beverage can or the like, with a metallic lid surface 13. The metallic lid surface 13 has a first, here upper, flat side 16 and a second, here lower, flat side 17 pointing away from the first flat side 16 ( 4 ) and is preferably formed from a sheet metal layer made of aluminum or tinplate. Preferably, the metallic cover surface 13 has a uniform thickness of 0.1 mm to 0.3 mm, preferably of about 0.2 mm. A coating of plastic material can be applied to the second flat side 17 of the metallic cover surface 13. In the embodiment shown, the metallic The metal lid surface 13 is circular in plan view and has a circle center 20. The can lid 11 can be connected to a beverage container via a flanged edge 18 of the metal lid surface 13.

An opening is provided in the metal lid surface 13, which is closed in the delivery state of the can lid 11 shown by a section of the metal lid surface 13 in the form of a closure piece 19. As in 2 As can be seen, the closure piece 19 is separated from the surrounding lid surface by a border in the form of a micro gap 21. The micro gap 21 runs within a plane and defines the 4 recognizable base plane 23 of the can lid 11. As shown, the opening is arranged decentrally in the metallic lid surface 13, i.e. the geometric center of the opening is spaced from the circle center 20.

The can lid 11 comprises a sealing frame made of plastic material which encloses the opening and is not visible in the figures and is firmly connected to the metal lid surface 13. Furthermore, a closing unit 29 made of plastic material is provided which carries the closure piece 19 and is pivotally connected to the sealing frame via a pivot bearing 30. A detachable fluid-tight connection between the sealing frame and the closing unit 29 is made possible by means of a locking device (not shown) which is formed by sealing and locking ribs and associated receiving grooves. The can lid 11 is therefore reclosable.

A ring-shaped tear-open member 37, preferably also made of plastic, is connected to the closing unit 29. By pulling on the tear-open member 37, a user can pivot the closure piece 19 upwards out of the base plane 23 and thus release the opening.

The closure piece 19 is in 3 shown individually. In the embodiment shown, the closure piece 19 has a rounded hexagonal shape. A first end region 61 of the closure piece 19 is connected to the pivot bearing 30 ( 1 ) and the sealing frame with the surrounding lid surface, while the ring-shaped tear-open member 37 acts via the closing unit 29 on a second end region 62 of the closure piece 19 opposite the pivot bearing 30. The two end regions 61, 62 are located at opposite rounded corners of the closure piece 19. As shown, the corner of the closure piece 19 associated with the second end region 62 is more pronounced than the other corners.

Between the first end region 61 and the second end region 62, the micro gap 21 is interrupted by a total of six retaining webs 65, via which the closure piece 19 and the surrounding cover surface are connected to one another in a materially bonded manner. A connecting line 67 runs through the two front retaining webs 65, i.e. the retaining webs 65 closest to the second end region 62.

When opening the can for the first time, a user pulls on the tear-open element 37 and thereby pivots the closing unit 29 with the closure piece 19 upwards. In doing so, the locking connection between the closing unit 29 and the sealing frame is released.

Due to the retaining webs 65, at the beginning of the pivoting process only a relatively small opening is created in the lid surface 13, which extends from the second end region 62 to the area of the two front retaining webs 65, i.e. approximately to the connecting line 67. The retaining webs 65 prevent any further opening, at least for a short time. The relatively small opening in the vicinity of the second end region 62 ensures that the can is ventilated. As the initial opening process continues, the retaining webs 65 tear one after the other. The closure piece 19 can then be pivoted completely upwards to expose the entire opening. Due to the gradual opening by the retaining webs 65 and the associated "venting" effect, there is no significant splashing, banging or foaming.

A support knob 31 with a flat support section 33 is embossed into the closure piece 19. The support knob 31 of the closure piece 19 is designed similarly to three other support knobs 34, 35, 39 ( 1 ), which are embossed into the area of the metal cover surface 13 surrounding the opening. All support knobs 34, 35, 39 have the same height 50 ( 4 ) on.

To avoid excessive material stress in the event of a pressure increase in the can, three embossed pressure relief shafts 77, 78, 79 ( 2 ) are provided, which extend parallel to one another at least partially around the opening. In particular, the radially innermost pressure relief shaft 77 has a closed circular course with the geometric center of the opening as the circle center. The middle pressure relief shaft 78 and the radially outermost pressure relief shaft 79 have respective circular arc-shaped courses with the geometric center of the opening as the circle center, but are not closed all the way around. Rather, the middle pressure relief shaft 78 and the radially outermost pressure relief shaft 79 are pressure shaft 79, the respective interruptions 80 being arranged such that they assume a position closest to the flanged edge 18. Preferably, the interruption 80 of the radially outermost pressure relief shaft 79 is longer than the interruption 80 of the middle pressure relief shaft 78, as shown. For example, the middle pressure relief shaft 78 can extend over an angle of approximately 300° and the radially outermost pressure relief shaft 79 can extend over an angle of approximately 250°.

In 5 the pressure relief waves 77, 78, 79 are shown in cross section. Each pressure relief wave 77, 78, 79 comprises a wave trough 81 extending transversely to the base plane 23 and having a curved cross section. Between the wave troughs 81 there are wave crests 82, which also have a curved cross section. It is preferred that the depth of the wave troughs 81 relative to the base plane 23 is at least as large as the thickness of the metallic cover surface 13 and at most twice the thickness of the metallic cover surface 13. As in 5 It can be seen that the amounts 85, 86, 87 of the depth of the wave troughs 81 relative to the base level 23 increase towards the opening, i.e. from the outside to the inside.

When the can lid 11 bulges as a result of a pressure increase in the can, the pressure relief shafts 77, 78, 79, starting with the radially innermost pressure relief shaft 77, are pulled apart to a certain extent. The three pressure relief shafts 77, 78, 79 running around the opening thus ensure a graduated mechanical decoupling of the opening area from the surrounding outer lid surface. In this way, the connection between the closure piece 19 and the surrounding lid surface is relieved.

Further relief is achieved by an elongated elevation 36 embossed into the closure piece 19, which rises in the direction of the first flat side 16 above the base plane 23, i.e. upwards in the embodiment shown. The elongated elevation 36 has a longitudinal axis 70 which is aligned transversely to the connecting line 67. Furthermore, the elongated elevation 36 has a club-like shape with a head section 89 near the edge and a tail section 90 which is narrower than the head section 89 near the edge. The tail section 90 is continuously tapered in a direction away from the head section 89. The head section 89 is arranged in the second end region 62, so that the elongated elevation 36 extends from the second end region 62 towards the first end region 61.

When the can lid 11 bulges as a result of an increase in pressure in the can, the central region of the closure piece 19 initially moves upwards. Due to the stiffening effect of the elevation 36, this movement of the central region is accompanied by a downward movement of the second end region 62. This means that the part of the closure piece 19 facing the second end region 62 pivots about the connecting line 67, whereby the transition between the closure piece 19 and the surrounding lid surface in the vicinity of the second end region 62 is relieved.

Furthermore, a closure relief bead 38 is embossed into the closure piece 19, which extends along the micro gap 21 and forms a depression with respect to the first flat side 16. This means that the closure relief bead 38 is embossed in the opposite direction with respect to the elongated elevation 36. In the embodiment shown, the closure relief bead 38 is closed all the way around and is curved alternately away from the micro gap 21 and towards the micro gap 21. The sections 95 curved away from the micro gap 21 are located next to the holding webs 65 and merge between the holding webs 65 into sections 96 curved towards the micro gap 21. This results in a flower-like pattern of the closure relief bead 38 in the top view. At the second end region 62, the closure relief bead 38 merges into the head section 89 of the elongated elevation 36.

It is preferred that the closure relief bead 38 has a depth relative to the base plane 23 which is at most as great as the thickness of the metallic cover surface 13. The outer flank facing the edge of the closure piece 19 is preferably less steep than the opposite inner flank.

In the event of a pressure increase in the can, the retaining webs 65 are decoupled from the central area of the closure piece 19 by the closure relief bead 38 and are thus protected against undesirable overloading.

The invention provides a resealable can lid 11 which is easy to open even when first opened and which nevertheless meets all stability requirements for pasteurization and storage of the can.

List of reference symbols:

11

can lids

13

metallic lid surface

16

first flat side

17

second flat side

18

flanged edge

19

closure piece

20

center of the circle

21

micro-gap

23

base level

29

closing unit

30

swivel bearing

31

support knob

33

flat support section

34

support knob

35

support knob

36

elongated elevation

37

tearing organ

38

closure relief bead

39

support knob

50

height of the support studs

61

first end area

62

second end area

65

pier

67

connecting line

70

longitudinal axis

77

internal pressure relief shaft

78

medium pressure relief wave

79

external pressure relief shaft

80

interruption

81

trough

82

Wellenberg

85

depth of the outer trough

86

depth of the mean trough

87

depth of the inner trough

89

head section

90

tail section

95

section curved away from the microgap

96

section curved towards the microgap

Claims (26)

Can lid (11), in particular for beverage cans, with a metallic lid surface (13) which has a first flat side (16) and a second flat side (17) pointing away from the first flat side (16), wherein an opening is formed in the lid surface (13) which is delimited by a closed edge of the lid surface (13) and which is closed by a closure piece (19) of the metallic lid surface (13), wherein the closure piece (19) is separated from the surrounding lid surface by a micro-gap (21) which extends at least in sections along the edge of the lid surface (13), wherein a base plane (23) of the closure piece (19) is defined by the course of the micro-gap (21), wherein a first end region (61) of the closure piece (19) is connected to the surrounding lid surface via a pivot bearing (30), and with a tear-open member (37) arranged on the first flat side (16) which is arranged on a side opposite the pivot bearing (30). second end region (62) of the closure piece (19), so that by pulling on the tear-open member (37) it is possible to pivot the closure piece (19) out of the base plane (23) in the direction of the first flat side (16), wherein the micro-gap (21) between the first end region (61) and the second end region (62) is interrupted by at least one retaining web (65), via which the closure piece (19) and the surrounding cover surface are materially connected to one another, characterized in that at least one pressure relief wave (77, 78, 79) is embossed into the metallic cover surface (13), which extends at least partially around the opening. can lid after claim 1 , characterized in that the pressure relief shaft (77, 78, 79) comprises a shaft trough (81) extending transversely to the base plane (23) and having a curved cross-section. can lid after claim 1 or 2 , characterized in that the pressure relief shaft (77, 78, 79) has a height or depth (85, 86, 87) relative to the base plane (23) which is at least half the thickness of the metallic cover surface (13) and at most four times the thickness of the metallic cover surface (13), wherein the height or depth (85, 86, 87) of the pressure relief shaft (77, 78, 79) is preferably at least as great as the thickness of the metallic cover surface (13) and at most twice the thickness of the metallic cover surface (13). Can lid according to one of the preceding claims, characterized in that the metallic lid surface (13) is rotationally symmetrical and the radial extension of the at least one pressure relief shaft (77, 78, 79), relative to the center of rotation (20) of the metallic lid surface, is at least twice and at most at least five times the thickness of the metallic cover surface (13). Can lid according to one of the preceding claims, characterized in that the at least one pressure relief wave (77, 78, 79) has a circular or circular arc-shaped course within the base plane (23). can lid after claim 5 , characterized in that the opening has a geometric center which coincides with the circle center of the circular or circular arc-shaped course of the at least one pressure relief shaft (77, 78, 79). Can lid according to one of the preceding claims, characterized in that at least two, preferably at least three and particularly preferably exactly three pressure relief waves (77, 78, 79) are embossed into the metallic lid surface (13), which extend parallel to one another at least partially around the opening. can lid after claim 7 , characterized in that the amounts (85, 86, 87) of the height or depth of the pressure relief shafts (77, 78, 79) relative to the base plane (23) increase towards the opening. can lid after claim 7 or claim 8 , characterized in that the arc lengths of the pressure relief shafts (77, 78, 79) increase towards the opening. Can lid after one of the Claims 7 until 9 , characterized in that the pressure relief shaft (77) closest to the opening has a closed circular course within the base plane (23) and at least one pressure relief shaft (78, 79) further away from the opening has an interrupted circular course. can lid after claim 10 , characterized in that the metallic cover surface (13) and the opening have respective geometric centers which are arranged at a distance from one another, wherein the at least one pressure relief shaft (78, 79) further away from the opening has an interruption (80) in the circular course through which a connecting line between the two geometric centers runs. Can lid (11), in particular for beverage cans, in particular according to one of the preceding claims, with a metallic lid surface (13) with a first flat side (16) and a second flat side (17) pointing away from the first flat side (16), wherein an opening is formed in the lid surface (13) which is delimited by a closed edge of the lid surface and is closed by a closure piece (19) of the metallic lid surface (13), wherein the closure piece (19) is separated from the surrounding lid surface by a micro-gap (21) extending at least in sections along the edge of the lid surface, wherein a base plane (23) of the closure piece (19) is defined by the course of the micro-gap (21), wherein a first end region (61) of the closure piece (19) is connected to the surrounding lid surface via a pivot bearing (30), and with a tear-open member (37) arranged on the first flat side (16), which is attached to a second End region (62) of the closure piece (19) engages so that by pulling on the tear-open member (37) the closure piece (19) can be pivoted out of the base plane (23) in the direction of the first flat side (16), wherein the micro-gap (21) between the first end region (61) and the second end region (62) is interrupted by at least two retaining webs (65) via which the closure piece (19) and the surrounding lid surface are materially connected to one another, characterized in that an elongated elevation (36) is embossed into the closure piece (19), which extends transversely to a line (67) which runs through two of the at least two retaining webs (65) and through the elongated elevation (36) and rises above the base plane (23) in the direction of the first flat side (16). can lid after claim 12 , characterized in that the elongated elevation (36) extends from the second end region (62) towards the first end region (61). can lid after claim 12 or 13 , characterized in that the opening has a geometric center and the elongated elevation (36) has a longitudinal axis (70) which runs through the geometric center of the opening. Can lid after one of the Claims 12 until 14 , characterized in that the elongated elevation (36) has a height relative to the base plane (23) which is at least as great as the thickness of the metallic cover surface (13) and at most four times the thickness of the metallic cover surface (13), wherein the height of the elongated elevation (36) is preferably at least one and a half times the thickness of the metallic cover surface (13) and at most three times the thickness of the metallic cover surface (13). Can lid after one of the Claims 12 until 15 , characterized in that the elongated elevation (36) has a length which is at least five times the thickness of the metallic cover surface (13) and at most seventy times the thickness of the metallic cover surface (13), wherein the length of the elongated elevation (36) is preferably at least twenty times the thickness of the metallic cover surface (13) and at most fifty times the thickness of the metallic cover surface (13). Can lid after one of the Claims 12 until 16 , characterized in that the opening has a rounded hexagonal shape and the elongated elevation (36) extends from a corner region of the opening towards an opposite corner region of the opening. Can lid after one of the Claims 12 until 17 , characterized in that the elongated elevation (36) has a club shape. Can lid after one of the Claims 12 until 18 , characterized in that the elongated elevation (36) has a head portion (89) close to the edge and a tail portion (90) narrower than the head portion (89). can lid after claim 19 , characterized in that the tail portion (90) is tapered in a direction away from the head portion (89), preferably continuously. Can lid (11), in particular for beverage cans, in particular according to one of the preceding claims, with a metallic lid surface (13) which has a first flat side (16) and a second flat side (17) pointing away from the first flat side (16), wherein an opening is formed in the lid surface (13) which is delimited by a closed edge of the lid surface (13) and which is closed by a closure piece (19) of the metallic lid surface (13), wherein the closure piece (19) is separated from the surrounding lid surface by a micro-gap (21) which extends at least in sections along the edge of the lid surface (13), wherein a first end region (61) of the closure piece (19) is connected to the surrounding lid surface via a pivot bearing (30), and with a tear-open member (37) arranged on the first flat side (16) which engages a second end region (61) of the closure piece (19) opposite the pivot bearing (30), so that by pulling the tear-open member (37) enables the closure piece (19) to pivot out of the base plane (23) defined by the opening in the direction of the first flat side (16), wherein the micro-gap (21) between the first end region (61) and the second end region (62) is interrupted by at least one retaining web (65), via which the closure piece (19) and the surrounding lid surface are materially connected to one another, characterized in that a closure relief bead (38) is embossed into the closure piece (19), which extends along the edge of the opening at least past the at least one retaining web (65). can lid after claim 21 , characterized in that the closure relief bead (38) is curved away from the edge in the region of the holding web (65). can lid after claim 22 , characterized in that the micro-gap (21) between the first end region (61) and the second end region (62) is interrupted by a plurality of retaining webs (65), via which the closure piece (19) and the surrounding cover surface are materially connected to one another, wherein the closure relief bead (38) extends past all retaining webs (65) and is curved away from the edge in the region of each retaining web (65). can lid after claim 23 , characterized in that the closure relief bead (38) is curved towards the edge in the region between two successive holding webs (65). Can lid after one of the Claims 21 until 24 , characterized in that the closure relief bead (38) has a height or depth relative to the base plane (23) which is at most one and a half times the thickness of the metallic cover surface (13), wherein the height or depth of the closure relief bead (38) is preferably at most as large as the thickness of the metallic cover surface (13). Can lid after one of the Claims 21 until 25 , characterized in that the closure relief bead (38) has a first flank facing the edge of the lid surface and a second flank facing away from the edge of the lid surface, the second flank being steeper than the first flank.

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