Can lid

Abstract

The can lid includes a metal lid surface having a first planar surface and a second planar surface facing opposite the first planar surface, the metal lid surface defining an opening closed by a closure piece bounded by a closed edge of the lid surface and separated from a surrounding lid surface by a microgap extending along the edge of the lid surface, the first lid region of the closure piece being connected to the surrounding lid surface via a pivot bearing, and further including a tear opening material disposed on the first planar surface and engaging a second lid region of the closure piece, the second lid region being opposite the pivot bearing such that pulling on the tear opening material allows the closure piece to pivot out of the reference plane in the direction of the first planar surface, the microgap being interrupted by at least one retention web between the first lid region and the second lid region. A pressure relief wave is embossed in the lid surface and extends around at least a portion of the periphery of the opening.

Description

Technical Field

[0003]

[0001] The present invention relates to a can lid, particularly to a can lid for a beverage can. The can lid includes a metallic lid surface having a first flat surface and a second flat surface facing the opposite side of the first flat surface. An opening is formed in the lid surface, which is bounded by the closed edge (margin) of the lid surface and is closed by a closure piece of the metallic lid surface. The closure piece is separated from the surrounding lid surface by a microgap that extends at least partially along the edge of the lid surface. The reference plane of the closure piece is defined by the course of the microgap. The first lid region of the closure piece is connected to the surrounding lid surface via a rotary bearing. Further, the can lid of the present invention further includes a tear-opening member disposed on the first flat surface and engaging with the second lid region of the closure piece. Since the second lid region is on the opposite side of the rotary bearing, by pulling the tear-opening member, the closure piece can be rotated out of the reference plane in the direction of the first flat surface. The microgap is interrupted by at least one holding web between the first lid region and the second lid region. The holding web connects the closure piece and the surrounding lid surface to each other in a manner that they are joined together.

Background Art

[0002] This type of can lid is widely used in the manufacture of beverage cans, food cans, etc. They are simple and low-cost to manufacture, enable space-saving stacking of the same type of cans, can be easily opened by manually moving the closure piece, and can be closed again if necessary. Due to the stepped opening and the accompanying venting effect by the holding web, no large spraying, popping, or foaming occurs during the first opening.

[0003] Generally, it is desirable that the initial opening of a can requires little or no force. However, this effort is negated by the need to prevent leaks as pressure rises inside the can, or to prevent the sealing film on the second flat surface from stretching. In practice, it is difficult to simultaneously ensure easy initial opening and stability against rising pressure. The pasteurization process required for many canned contents such as juices and food is particularly challenging. The pasteurization process involves pressures of, for example, 6 bar, which can place considerable stress on the material. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The object of the present invention is to provide a can lid that is easy to open and has high resistance to pressure increases inside the can connected to the lid. [Means for solving the problem]

[0005] The object of the present invention is to be filled by a can lid having the features of claim 1.

[0006] According to the present invention, at least one pressure relief wave is embossed on the metal lid surface and extends around at least a portion of the opening. The pressure relief wave ensures that the inner region including the opening is mechanically decoupled from the surrounding outer lid surface. If the can lid bulges upward as a result of rising pressure inside the can, or continues to bulge upward from a curved state, the pressure relief wave is pulled apart to some extent, and the material is released inward, so to speak. In this way, the connection between the closure piece and the surrounding lid surface, and in particular between the retaining web, is relieved. Can lids with pressure relief waves have been shown to be easy to open and, on the one hand, easy to open, and on the other hand, to reliably withstand relatively high pressure values.

[0007] The pressure-relaxing wave section may have a curved cross-section and include wave troughs extending across the reference plane. The curved path ensures a certain degree of flexible coupling between the inner and outer lid regions, thereby contributing to the stabilization of the closed opening when the can lid bulges upward.

[0008] The pressure-relaxing wave portion may be specified to have a height or depth of at least half the thickness of the metal lid surface relative to the reference plane, and a maximum height or depth of four times the thickness of the metal lid surface. The height or depth of the pressure-relaxing wave portion is preferably at least equal to the thickness of the metal lid surface, and a maximum of twice the thickness of the metal lid surface. Here, the height or depth of the metal lid surface should be understood as a uniform or average thickness. The height or depth of the pressure-relaxing wave portion is preferably uniform along its longitudinal direction. Such specified heights or depths have proven to be very advantageous in practice.

[0009] According to embodiments of the present invention, the metal lid surface is rotationally symmetric, and the radial range of at least one pressure-releasing wave portion is at least twice and up to five times the thickness of the metal lid surface with respect to the rotation center of the metal lid surface. A pressure-releasing wave portion of appropriate width ensures that the opening function is performed particularly reliably.

[0010] At least one pressure relief wave preferably has a circular or arched path within the reference plane. This results in a very uniform relief effect, especially in the case of a circular lid surface.

[0011] The opening may have a geometric center that coincides with the center of the circle of the circular or arched path of at least one pressure-relaxing wave section. This further promotes a uniform relaxation effect.

[0012] According to a further embodiment of the present invention, at least two, preferably at least three, and especially preferably just three pressure-releasing wave portions are embossed on the metal lid surface and extend parallel to each other in at least a portion of the perimeter of the opening. This enhances the relaxation effect. Furthermore, the presence of multiple parallel pressure-releasing wave portions allows for gradual relaxation in customized embodiments.

[0013] The magnitude of the height or depth of the pressure-relaxing wave relative to the reference plane preferably increases towards the opening. This allows the innermost radial pressure-relaxing wave to provide maximum flexibility. Such gradual pressure relaxation has proven particularly advantageous.

[0014] In specific embodiments, the arc length of the pressure-relaxing wave increases toward the opening. Generally, the further the pressure-relaxing wave is from the opening, the less expandability is required.

[0015] Preferably, the pressure-relaxing wave portion located closest to the opening has a closed circular path within the reference plane, while at least one pressure-relaxing wave portion located further from the opening has a suspended circular path. For example, the suspended portion may be located in the region where the opening is located closest to the edge of the lid surface. Under certain circumstances, there is no space in this region to further arrange a circular pressure-relaxing wave portion. However, a pressure-relaxing wave portion having a suspended path may be provided. A particularly preferred embodiment comprises one closed inner pressure-relaxing wave portion and two suspended outer pressure-relaxing wave portions.

[0016] According to a specific embodiment of the present invention, the metal lid and opening have respective geometric centers that are spaced apart from each other, and at least one pressure-releasing wave portion located further from the opening has an interruption in the circular path, with a line connecting the two geometric centers extending through the interruption. For example, the metal lid and opening may be rotationally symmetric, particularly circular, with their respective centers of rotation forming the geometric centers.

[0017] The present invention relates to a can lid, and more particularly to a can lid for a beverage can. The can lid includes a metal lid surface, as described above, the metal lid surface having a first flat surface and a second flat surface facing opposite the first flat surface. An opening is formed in the lid surface, the opening is bounded by a closed edge of the lid surface and closed by a closure piece of the metal lid surface. The closure piece is separated from the surrounding lid surface by a microgap that extends at least partially along the edge of the lid surface. The reference plane of the closure piece is defined by the path of the microgap. The first lid region of the closure piece is connected to the surrounding lid surface via a pivot bearing. The can lid of the present invention also includes a tear-opening member disposed on the first flat surface and engaging with the second lid region of the closure piece. Since the second lid region is on the opposite side of the pivot bearing, pulling the tear-opening member allows the closure piece to be rotated out of the reference plane in the direction of the first flat surface. The microgap is interrupted between the first lid region and the second lid region by at least two retaining webs. The closure piece and the surrounding lid surface are connected to each other via these retaining webs in a coupled manner.

[0018] The more retaining webs there are, and the wider they are, the more stably the closure piece is accommodated in the opening. However, stable fitting of the closure piece makes the initial opening more difficult. As mentioned above, ensuring both easy initial opening and sufficient stability against pressure increases simultaneously is a challenging task.

[0019] To solve this problem, according to one aspect of the present invention, an elongate elevated portion is embossed on the closure piece, the elongate elevated portion rising above the reference plane in the direction of the first flat surface and extending across a line that passes through at least two of the two retaining webs and extends through the elongate elevated portion.

[0020] When the can lid bulges upward as a result of increased pressure inside the can, the central region of the closure piece moves upward first. The raised portion has a stiffening effect and, due to its shape and orientation, ensures that the upward movement of the central region is accompanied by the downward movement of the surrounding region, like a lever. As a result, a virtual axis of rotation is formed that extends parallel to or coincides with the line connecting the two retaining webs. This mitigates the transition between the closure piece and the surrounding lid surface and prevents unwanted separation of the metal edge in the microgap. It has become clear that the effect of the elongated raised portion makes it possible to tear the retaining webs and retract them further overall from the engagement point of the opening material than before. Such retraction is particularly advantageous because it improves the venting effect.

[0021] The elongated protrusion may extend from the second lid region toward the first lid region. This means that the elongated protrusion may extend from the engagement point of the tear-opening material toward the rotating bearing. When the can lid bulges upward, the region of the tear-opening point is particularly relaxed. This is advantageous because the retaining web for venting should be as far away from the tear-opening point as possible, and this region is particularly susceptible to the effects of pressure loads.

[0022] According to a further embodiment of the present invention, the opening has a geometric center, and the elongated protrusion has a longitudinal axis extending through the geometric center of the opening. This ensures a particularly advantageous mitigation effect.

[0023] The elongated protrusion is preferably at least the same thickness as the metal lid surface and up to four times the thickness of the metal lid surface relative to the reference surface. The height of the elongated protrusion is particularly preferably at least 1.5 times the thickness of the metal lid surface and up to three times the thickness of the metal lid surface. Such heights have proven to be very advantageous in general applications.

[0024] The elongated raised portion preferably has a length that is at least five times and at most 70 times the thickness of the metal lid surface. The length of the elongated raised portion is particularly preferably at least 20 times and at most 50 times the thickness of the metal lid surface. Such a length of the raised portion ensures a very good fit of the reinforcing effect to the standard lid design.

[0025] It is possible to provide a stipulation that the opening has a rounded hexagonal shape and the elongated raised portion extends from the corner region of the opening to the corner region on the opposite side of the opening. Specifically, the elongated raised portion can extend from the corner region that coincides with the second lid region. Tearing open at that corner enables particularly advantageous ventilation. At the same time, the raised portion ensures that the closure piece does not loosen earlier than normal at that corner. The rounded hexagonal shape of the opening is advantageous in that the installation of the retaining web in the straight portion is particularly simple.

[0026] The elongated raised portion can have a rod shape. Thereby, a particularly advantageous stepwise reinforcing effect is obtained.

[0027] According to a specific embodiment, the elongated raised portion has a head near the edge and a tail that is narrower with respect to the head. It has become clear that a particularly significant improvement in stability is desired in the edge region.

[0028] The tail can preferably become gradually thinner continuously in the direction opposite to the head. As a result, the reinforcing effect decreases as it moves away from the tear opening point, which has been proven to be particularly advantageous.

[0029] Furthermore, the present invention relates to a can lid, particularly to a can lid for a beverage can. The can lid includes a metallic lid surface, which, as particularly described above, has a first flat surface and a second flat surface facing the side opposite to the first flat surface. An opening is formed in the metallic lid surface, which is bounded by the closed edge of the lid surface and is closed by a closure piece of the metallic lid surface. The closure piece is separated from the surrounding lid surface by a microgap extending at least partially along the edge of the lid surface. The first lid region of the closure piece is connected to the surrounding lid surface via a rotation bearing. Also, the can lid of the present invention includes a tear-opening member disposed on the first flat surface and engaging with the second lid region of the closure piece. Since the second lid region is on the side opposite to the rotation bearing, by pulling the tear-opening member, it is possible to rotate the closure piece out of the reference plane defined by the opening in the direction of the first flat surface. The microgap is interrupted by at least two holding webs between the first lid region and the second lid region. By the holding webs, the closure piece and the surrounding lid surface are connected to each other in a manner of being coupled together.

[0030] In order to solve the initially stated problem, according to a further aspect of the present invention, a closure relief bead is embossed on the closure piece, extending along the edge of the opening, at least passing through at least one holding web.

[0031] When the pressure inside the can rises, the holding web is separated from the central region of the closure piece by the closure relief bead and is protected from unnecessary overloading. Since the stretching of the lid surface is compensated by the closure relief bead, overloading of the holding web or breakage of the holding web does not occur.

[0032] The closure relief bead can be curved away from the edge in the region of the holding web. In this design, the closure relief bead particularly effectively shields the holding web from the central region of the closure piece.

[0033] Multiple retaining webs can be used to define a microgap between the first and second lid regions. The closure piece and the surrounding lid surface are connected to each other via these retaining webs, and the closure relief bead extends in a curved manner, passing through all the retaining webs and away from the edges within each retaining web region. Thus, all retaining webs are protected from excessive load.

[0034] The closure relaxation bead preferably curves toward the edge in the region between two consecutive retaining webs. This allows for the formation of a closed peripheral closure relaxation bead, even though the curved portion is away from the edge in the region of the retaining web.

[0035] A further embodiment of the present invention provides that the closure relief bead has a height or depth of up to 1.5 times the thickness of the metal lid surface relative to the reference surface, and preferably the height or depth of the closure relief bead is up to approximately the same as the thickness of the metal lid surface. This has proven particularly advantageous in general lid designs.

[0036] The closure relief bead preferably has a first flank facing the edge of the lid and a second flank facing the opposite side of the lid, the second flank being steeper than the first flank. As a result, a particularly advantageous relief effect is obtained.

[0037] The combination of the pressure-relaxing wave section described above, the elongated ridge section described above, and / or the closure-relaxing bead has proven particularly advantageous. Cans featuring the relaxation described above have a gradual effect. For example, if the pressure rises gradually, only the pressure-relaxing wave section may begin to function first, and only when a higher threshold is exceeded may the retaining web be protected by the closure-relaxing bead.

[0038] Further developments of the present invention can be found in the dependent claims, the following specification, and the accompanying drawings.

[0039] The present invention is described below, with reference to the drawings, as an example. [Brief explanation of the drawing]

[0040] [Figure 1] Figure 1 is a plan view of the can lid in the closed state according to the present invention. [Figure 2] Figure 2 shows the can lid as shown in Figure 1, excluding the closing component. [Figure 3] Figure 3 is a diagram showing the individual closure pieces of the can lid as shown in Figure 2. [Figure 4] Figure 4 is a cross-sectional view of the closure piece in Figure 3 along line AA. [Figure 5] Figure 5 is a cross-sectional view showing the arrangement of the pressure-relieving wave portion of the can lid according to Figure 1. [Modes for carrying out the invention]

[0041] Figures 1 and 2 show a can lid 11 designed according to the present invention, which is intended for use on beverage cans and the like, and has a metal lid surface 13. The metal lid surface 13 is The metal end face has a first, in this case upper (front) flat surface 16 and a second, in this case lower (back) flat surface 17 (Figure 4) facing the opposite side from the first flat surface 16. The metal lid surface 13 is preferably formed from a sheet metal layer made of aluminum or tin. The metal lid surface 13 preferably has a uniform thickness of 0.1 mm to 0.3 mm, preferably about 0.2 mm. A coating made of plastic material may be applied to the second flat surface 17 of the metal lid surface 13. In the illustrated embodiment, the metal lid surface 13 is circular in plan view and has a center 20 of the circle. The can lid 11 can be connected to a beverage container via a beaded rim 18 of the metal lid surface 13.

[0042] An opening is provided in the metal lid surface 13, which is closed by a portion of the metal lid surface 13 acting as a closure piece 19 in the shipping state of the illustrated can lid 11. As can be seen in Figure 2, the closure piece 19 is separated from the surrounding lid surface by a boundary line acting as a microgap 21. The microgap 21 extends within a single plane and defines the reference plane 23 of the can lid 11, as can be seen in Figure 4. As illustrated, the opening is offset on the metal lid surface 13, that is, the geometric center of the opening is away from the center 20 of the circle.

[0043] The can lid 11, although not shown, includes a sealing frame made of plastic material surrounding the opening, which is fixedly connected to the metal lid surface 13. A closure unit 29, also made of plastic material, is further provided to support a closure piece 19 and is rotatably connected to the sealing frame via a pivot bearing 30. A releasable liquid-tight connection between the sealing frame and the closure unit 29 is made possible by a latching device, not shown, formed by a sealing and latching rib and associated receiving grooves. Thus, the can lid 11 is re-closable.

[0044] Here, an annular tear-opening member 37, preferably also made of plastic, is connected to the closure unit 29. By pulling the tear-opening member 37, the user can rotate the closure piece 19 upward away from the reference plane 23, thereby releasing the opening.

[0045] The closure piece 19 is shown individually in Figure 3. In the illustrated embodiment, the closure piece 19 has a rounded hexagonal shape. The first lid region 61 of the closure piece 19 is connected to the surrounding lid surface via the pivot bearing 30 (Figure 1) and the sealing frame, and the annular tear-off opening material 29 engages with the second lid region 62 of the closure piece 19. The second lid region 62 is on the opposite side of the pivot bearing 30 via the closure unit 29. The two lid regions 61, 62 are located at the rounded, opposing corners of the closure piece 19. As shown, the corner of the closure piece 19 associated with the second lid region 62 is more prominent than the other corners.

[0046] Between the first lid region 61 and the second lid region 62, the microgap 21 is interrupted by a total of six retaining webs 65. These retaining webs 65 connect the closure piece 19 to the surrounding lid surface in a coupled manner. A connecting line 67 extends through the two front retaining webs 65, i.e., the retaining web 65 closest to the second lid region 62.

[0047] When opening the can for the first time, the user pulls the tear-off opening material 37, thereby rotating the closure unit 29, which has the closure piece 19, upward. At this point, the latch connection between the closure unit 29 and the sealing frame is released.

[0048] The retaining web 65 creates only a relatively small opening on the lid surface 13 at the start of the rotation process, and this opening extends from the second lid region 62 to the region of the two front retaining webs 65, i.e., around the connecting line 67. The retaining web 65 prevents further opening, at least for a short period. The relatively small opening around the second lid region 62 allows for ventilation (venting) of the can. As the initial opening process progresses further, the retaining web 65 tears one after another. As a result, the closure piece 19 can rotate completely upward to open the entire opening. In this respect, the stepwise opening by the retaining web 65 and the associated venting effect prevent large sprays, blowouts, or foaming.

[0049] The support nub 31 includes a flat support portion 33 and is embossed on the closure piece 19. The support nub 31 of the closure piece 19 has a similar shape to three further support nubs 34, 35, 39 (Figure 1) which are embossed in the area surrounding the opening of the metal lid surface 13. The support nubs 34, 35, 39 have the same height 50 (Figure 4).

[0050] Three embossed pressure-relieving wave sections 77, 78, and 79 (Figure 2) extend parallel to each other in at least a portion of the perimeter of the opening and are provided to prevent excessive material stress when the pressure inside the can rises. Specifically, the innermost radial pressure-relieving wave section 77 has a closed circular path with the geometric center of the opening as the center of the circle. The intermediate pressure-relieving wave section 78 and the outermost radial pressure-relieving wave section 79 each have arched paths with the geometric center of the opening as the center of the circle, but their peripheries are not closed. Rather, the intermediate pressure-relieving wave section 78 and the outermost radial pressure-relieving wave section 79 are interrupted by interruption sections 80 positioned to occupy the position closest to the bead rim 18. As shown, the interruption section 80 of the outermost radial pressure-relieving wave section 79 is preferably longer than the interruption section 80 of the intermediate pressure-relieving wave section 78. For example, the intermediate pressure-relaxing wave portion 78 may extend over an angle of approximately 300°, and the outermost pressure-relaxing wave portion 79 in the radial direction may extend over an angle of approximately 250°.

[0051] Cross-sectional views of the pressure-relaxing wave sections 77, 78, and 79 are shown in Figure 5. Each of the pressure-relaxing wave sections 77, 78, and 79 has a curved cross-section and includes a wave trough 81 that extends across the reference plane 23. Between the wave troughs 81, there are wave peaks 82 that have similarly curved cross-sections. The depth of the wave troughs 81 relative to the reference plane 23 is at least the same as the thickness of the metal cover surface 13, and preferably at most twice the thickness of the metal cover surface 13. As shown in Figure 5, the magnitudes 85, 86, and 87 of the depths of the wave troughs 81 relative to the reference plane 23 increase toward the opening, i.e., from the outside to the inside.

[0052] If the can lid 11 bulges upward as a result of increased pressure inside the can, the pressure relief wave portions 77, 78, and 79 are pulled apart to some extent, starting with the radially innermost pressure relief wave portion 77. This ensures that the three pressure relief wave portions 77, 78, and 79 extending around the opening mechanically separate the opening region from the surrounding outer lid surface in stages. In this way, the connection between the closure piece 19 and the surrounding lid surface is relaxed.

[0053] Further relaxation is achieved by an elongated ridge 36 embossed on the closure piece 19 and exposed on the reference surface 23 in the direction of the first flat surface 16, i.e., upward in the illustrated embodiment. The elongated ridge 36 has a longitudinal axis 70 oriented in a direction perpendicular to the connecting line 67. Furthermore, the elongated ridge 36 has a club shape and has a head 89 near the edge and a tail 90 that narrows in relation to the head 89 near the edge. The tail 90 tapers continuously in the direction opposite to the head. Since the head 89 is located in the second lid region 62, the elongated ridge 36 extends from the second lid region 62 toward the first lid region 61.

[0054] When the can lid 11 bulges upward as a result of increased pressure inside the can, the central region of the closure piece 19 moves upward first. Due to the reinforcing effect of the raised portion 36, this movement of the central region is accompanied by the downward movement of the second lid region 62. That is, the portion of the closure piece 19 facing the second lid region 62 rotates around the connecting line 67, thereby mitigating the transition between the closure piece 19 and the surrounding lid surface around the second lid region 62.

[0055] Furthermore, the closure relief bead 38 is embossed on the closure piece 19 and extends along the microgap 21, forming a recess in the first flat surface 16. This means that the closure relief bead 38 is embossed in the opposite direction to the elongated raised portion 36. In the illustrated embodiment, the closure relief bead 38 is closed at the periphery and curves alternately away from the microgap 21 and toward the microgap 21. The portion 95 curving away from the microgap 21 is located next to the retaining web 65 and merges between the retaining webs 65 with the portion 96 curving toward the microgap 21. This creates a flower-like pattern of the closure relief bead 38 in the plan view. In the second lid region 62, the closure relief bead 38 merges with the head 89 of the elongated raised portion 36.

[0056] The closure relaxation bead 38 preferably has a depth of up to approximately the same as the thickness of the metal cover surface 13 relative to the reference surface 23. The outer flank facing the edge of the closure piece 19 preferably has a smaller slope than the inner flank on the opposite side.

[0057] If the pressure inside the can increases, the retaining web 65 is separated from the central region of the closure piece 19 by the closure relief bead 38, thereby protecting it from unwanted excessive load.

[0058] The present invention provides a resealable can lid 11 that can be easily opened even on its initial opening, and nevertheless meets all stability requirements for pasteurization and can storage. [Explanation of Symbols]

[0059] 11 Can lid 13 Metal lid surface 16 First flat surface 17. Second flat surface 18 Bead Rim 19 closure pieces Center of 20 yen 21 microgap 23 Reference plane 29 Closure Unit 30 Rotating bearings 31 Support Nubs 33 Flat support section 34 Support Nubs 35 Support Nubs 36. Elongated raised portion 37 Tear-off opening material 38 Closure relief bead 39 Support Nab 50 Height of support nubs 61 First lid region 62 Second lid area 65 retain web 67 connecting lines 70 Long axis 77 Inner pressure relaxation wave 78 Intermediate pressure relaxation wave 79 Outer pressure relaxation wave 80 Interruption 81. The trough of the wave 82 Peak of the wave 85 Depth of the outer wave trough 86 Depth of the trough of the intermediate wave 87 Depth of the inner wave trough 89 Head 90 Tail 95. The part that curves away from the microgap. 96. The part that curves in the direction toward the microgap.

Claims

1. A can lid (11), Including a metal lid surface (13), the metal lid surface (13) has a first flat surface (16) and a second flat surface (17) facing opposite to the first flat surface (16), the lid surface (13) has an opening formed therein, bounded by a closed edge of the lid surface (13) and closed by a closure piece (19) of the metal lid surface (13), the closure piece (19) being separated from the surrounding lid surface by a microgap (21) extending at least partially along the edge of the lid surface (13), the reference surface (23) of the closure piece (19) being defined by the path of the microgap (21), and the first lid region (61) of the closure piece (19) being connected to the surrounding lid surface via a pivot bearing (30), The present invention further includes a tear-opening member (37) positioned on the first flat surface (16) and engaging with a second lid region (62) of the closure piece (19), the second lid region (62) being on the opposite side of the pivot bearing (30), so that by pulling the tear-opening member (37), the closure piece (19) can be rotated out of the reference plane (23) in the direction of the first flat surface (16), the microgap (21) being interrupted between the first lid region (61) and the second lid region (62) by at least one retaining web (65), the closure piece (19) and the surrounding lid surface being connected to each other via the retaining web (65), A can lid characterized in that at least one pressure-relaxing wave portion (77, 78, 79) is embossed on the metal lid surface (13) and extends to at least a portion of the periphery of the opening.

2. A can lid according to claim 1, The can lid is characterized in that the pressure-relaxing wave portions (77, 78, 79) have a curved cross-section and include wave troughs (81) that extend across the reference plane (23).

3. A can lid according to claim 1 or 2, The can lid is characterized in that the pressure-relaxing wave portions (77, 78, 79) have a height or depth (85, 86, 87) that is at least half the thickness of the metal lid surface (13) and at most four times the thickness of the metal lid surface (13) with respect to the reference surface (23).

4. A can lid according to claim 1 or 2, The can lid is characterized in that the metal lid surface (13) is rotationally symmetric, and the radial range of the at least one pressure-relaxing wave portion (77, 78, 79) is at least twice and up to five times the thickness of the metal lid surface (13) with respect to the rotation center (20) of the metal lid surface (13).

5. A can lid according to claim 1 or 2, characterized in that the at least one pressure-relaxing wave portion (77, 78, 79) has a circular or arc-shaped path within the reference plane (23).

6. A can lid according to claim 5, The can lid is characterized in that the opening has a geometric center that coincides with the center of the circle of the circular or arc-shaped path of the at least one pressure-relaxing wave portion (77, 78, 79).

7. A can lid according to claim 1, A can lid characterized in that at least two pressure-relaxing wave portions (77, 78, 79) are embossed on the metal lid surface (13) and extend parallel to each other in at least a portion of the periphery of the opening.

8. A can lid according to claim 7, A can lid characterized in that the height or depth (85, 86, 87) of the pressure-relaxing wave portions (77, 78, 79) relative to the reference surface (23) increases toward the opening.

9. A can lid according to claim 7 or 8, A can lid characterized in that the arc length of the pressure-relaxing wave portion (77, 78, 79) increases toward the opening.

10. A can lid according to any one of claims 7 or 8, A can lid characterized in that the pressure-relaxing wave portion (77) located closest to the opening has a closed circular path within the reference plane (23), and at least one pressure-relaxing wave portion (78, 79) located further away from the opening has an interrupted circular path.

11. A can lid according to claim 10, A can lid characterized in that the metal lid surface (13) and the opening have their respective geometric centers spaced apart from each other, and the at least one pressure-relaxing wave portion (78, 79) located further away from the opening has a circular interruption portion (80) of the path, and a line connecting the two geometric centers extends through the interruption portion.

12. A can lid (11), Including a metal lid surface (13), the metal lid surface (13) has a first flat surface (16) and a second flat surface (17) facing opposite to the first flat surface (16), and the lid surface (13) has an opening formed therein, which is bounded by a closed edge of the lid surface (13) and closed by a closure piece (19) of the metal lid surface (13), the closure piece (19) being separated from the surrounding lid surface by a microgap (21) that extends at least partially along the edge of the lid surface, and the reference plane (23) of the closure piece (19) being defined by the path of the microgap (21), The first lid region (61) of the closure piece (19) is connected to the surrounding lid surface via a rotating bearing (30), The present invention further includes a tear-opening member (37) positioned on the first flat surface (16) and engaging with a second lid region (62) of the closure piece (19), the second lid region (62) being on the opposite side of the pivot bearing (30), so that by pulling the tear-opening member (37), the closure piece (19) can be rotated out of the reference plane (23) in the direction of the first flat surface (16), the microgap (21) being interrupted between the first lid region (61) and the second lid region (62) by at least two retaining webs (65), the closure piece (19) and the surrounding lid surface being connected to each other via the retaining webs (65), A can lid characterized in that an elongated raised portion (36) is embossed on the closure piece (19), the elongated raised portion (36) extends across a line (67) that passes through two of the at least two retaining webs and extends through the elongated raised portion (36), and rises above the reference surface (23) in the direction of the first flat surface (16).

13. A can lid according to claim 12, The can lid is characterized in that the elongated protrusion (36) extends from the second lid region (62) in the direction of the first lid region (61).

14. A can lid according to claim 12 or 13, The can lid is characterized in that the opening has a geometric center, and the elongated raised portion (36) has a longitudinal axis (70) that extends through the geometric center of the opening.

15. A can lid according to claim 12 or 13, The can lid is characterized in that the elongated protrusion (36) has a height of at least the same as the thickness of the metal lid surface (13) relative to the reference surface (23), and at most four times the thickness of the metal lid surface (13).

16. A can lid according to claim 12 or 13, The can lid is characterized in that the elongated protrusion (36) is at least five times the thickness of the metal lid surface (13) and has a maximum length of 70 times the thickness of the metal lid surface (13).

17. A can lid according to claim 12 or 13, The can lid is characterized in that the opening has a rounded hexagonal shape, and the elongated protrusion (36) extends from the corner region of the opening toward the opposite corner region of the opening.

18. A can lid according to claim 12 or 13, The can lid is characterized in that the elongated protruding portion (36) has a club shape.

19. A can lid according to claim 12 or 13, The can lid is characterized in that the elongated raised portion (36) has a head portion (89) near the edge and a tail portion (90) that is narrower than the head portion (89).

20. A can lid according to claim 19, The can lid is characterized in that the tail portion (90) gradually tapers in the direction opposite to the head portion (89).

21. A can lid (11), The present invention includes a metal lid surface (13), the metal lid surface (13) having a first flat surface (16) and a second flat surface (17) facing opposite to the first flat surface (16), the lid surface (13) having an opening bounded by a closed edge of the lid surface (13) and closed by a closure piece (19) of the metal lid surface (13), the closure piece (19) being separated from the surrounding lid surface by a microgap (21) that extends at least partially along the edge of the lid surface, The first lid region (61) of the closure piece (19) is connected to the surrounding lid surface via a rotating bearing (30), The present invention further includes a tear-opening member (37) positioned on the first flat surface (16) and engaging with a second cover region (62) of the closure piece (19), the second cover region (62) being on the opposite side of the pivot bearing (30), so that by pulling the tear-opening member (37), the closure piece (19) can be rotated toward the first flat surface (16) and away from the reference plane (23) defined by the opening. The microgap (21) is interrupted between the first lid region (61) and the second lid region (62) by at least one retaining web (65), and the closure piece (19) and the surrounding lid surface are connected to each other via the retaining web (65) in such a manner that they are coupled. A can lid characterized in that a closure relief bead (38) is embossed on the closure piece (19) and extends along the edge of the opening, passing through at least one retaining web.

22. A can lid according to claim 21, The can lid is characterized in that the closure relief bead (38) is curved away from the edge in the region of the retaining web (65).

23. A can lid according to claim 22, The can lid is characterized in that the microgap (21) is interrupted by a plurality of retaining webs (65) between the first lid region (61) and the second lid region (62), and the closure piece (19) and the surrounding lid surface are connected to each other via the plurality of retaining webs (65), and the closure relief bead (38) extends in a curved manner, passing through all of the retaining webs (65) and away from the edges in the region of each retaining web (65).

24. A can lid according to claim 23, The can lid is characterized in that the closure relief bead (38) is curved toward the edge in the region between two consecutive retaining webs (65).

25. A can lid according to any one of claims 21 to 24, The can lid is characterized in that the closure relief bead (38) has a height or depth of up to 1.5 times the thickness of the metal lid surface (13) relative to the reference surface (23).

26. A can lid according to any one of claims 21 to 24, The closure relief bead (38) has a first side surface facing the edge of the lid surface and a second side surface facing the opposite side of the edge of the lid surface, wherein the second side surface is steeper than the first side surface.

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