CAN END

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 U.S.C. 371 of PCT Application No. PCT/EP2024/055632 having an international filing date of Mar. 4, 2024, which claims the benefit of German Patent Application No. 102023109429.7, filed Apr. 14, 2023, the entire disclosure of each of which are hereby incorporated herein by reference.

INTRODUCTION

The invention relates to a can end, in particular for beverage cans, comprising a metallic end surface that has a first flat side and a second flat side facing away from the first flat side, wherein an opening is formed in the end surface, which opening is bounded by a closed margin of the end surface and 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, wherein a base plane of the closure piece is defined by the course of the microgap, wherein a first end region of the closure piece is connected to the surrounding end surface via a pivot bearing; and a tear-open member that is arranged at the first flat side and that engages at a second end region of the closure piece, said second end region being opposite the pivot bearing, so that a pivoting of the closure piece out of the base plane in the direction of the first flat side is made possible by pulling at the tear-open member, wherein 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.

Can ends of this kind are used on a large scale for the manufacture of beverage cans, food cans and the like. They are simple and inexpensive to manufacture, enable a space-saving stacking of cans of the same kind and can be easily opened and, if necessary, closed again by manually moving the closure piece. Due to the opening graduated by the holding web and the associated venting effect, no significant spraying, popping or foaming over occurs during the initial opening.

It is generally desired that the first opening of the can only requires little effort. However, this endeavor is countered by the necessity that, even with a pressure increase in the interior of the can, leaks may not occur in the region of the opening or a stretching of a sealing film provided at the second flat side may not occur. In practice, it is difficult to simultaneously ensure an easy initial opening and a sufficient stability at elevated pressure. A particular challenge is the pasteurization process that is necessary for many can contents such as juices, meals and the like, that is accompanied, for example, by a pressure of 6 bar and that can lead to considerable material stress.

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

The object is satisfied, on the one hand, by a can end having the features of claim 1.

SUMMARY

According to the invention, at least one pressure relief wave is embossed into the metallic end surface and extends at least partly around the opening. The pressure relief wave ensures a mechanical decoupling of the inner region comprising the opening from the surrounding outer end surface. If the can end bulges upwards as a result of a pressure increase in the can or continues to bulge upwards starting from a curved state, the pressure relief wave is pulled apart to a certain extent so that material is so-to-say discharged inwards. In this way, the connection between the closure piece and the surrounding end surface and in particular the holding web is relieved. It has been shown that a can end provided with a pressure relief wave is easy to open, on the one hand, and reliably withstands relatively high pressure values, on the other hand.

The pressure relief wave can comprise a wave trough having a curved cross-section and extending transversely to the base plane. The curved course ensures a flexible coupling between the inner and the outer end region to a certain degree and thus contributes to a stabilization of the closed opening when the can end bulges upwards.

Provision can be made that the pressure relief wave has, with respect to the base plane, a height or depth that is at least half the thickness of the metallic end surface and at most four times the thickness of the metallic end surface, with the height or depth of the pressure relief wave preferably being at least as great as the thickness of the metallic end surface and at most twice the thickness of the metallic end surface. The thickness of the metallic end surface is to be understood here as a uniform or average thickness. The height or depth of the pressure relief wave is preferably uniform along its longitudinal extent. A height or depth as specified has proven to be particularly favorable in practice.

According to one embodiment of the invention, the metallic end surface is rotationally symmetrical and the radial extent of the at least one pressure relief wave, with respect to the center of rotation of the metallic end surface, is at least twice and at most five times the thickness of the metallic end surface. A pressure relief wave of the appropriate width fulfills the relief function particularly reliably.

The at least one pressure relief wave preferably has a circular or arcuate course within the base plane. A particularly uniform relief effect thereby results, in particular in the case of a circular end surface.

The opening can have a geometric center that coincides with the circle center of the circular or arcuate course of the at least one pressure relief wave. 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 metallic end surface and extend parallel to one another at least partly around the opening. The relief effect is hereby increased. Furthermore, the presence of a plurality of parallel pressure relief waves enables a graduation of the relief in a customized manner.

The magnitudes of the height or depth of the pressure relief waves related to the base plane preferably increase toward the opening. The radially innermost pressure relief wave thus provides the greatest flexibility. Such graduated pressure relief has proven to be particularly favorable.

According to a specific embodiment, the arc lengths of the pressure relief waves increase toward the opening. In general, the further away the pressure relief wave is from the opening, the less expansion potential is required.

It is preferred that the pressure relief wave disposed closest to the opening has a closed circular course within the base plane and at least one pressure relief wave disposed further away from the opening has an interrupted circular course. For example, an interruption can be arranged in a region in which the opening is disposed closest to the margin of the end surface. Under certain circumstances, there is no space for a further circulating pressure relief wave in this region. However, a pressure relief wave with an interrupted course can already be provided. A particularly preferred embodiment provides one closed inner pressure relief wave and two interrupted outer pressure relief waves.

A specific embodiment of the invention provides that the metallic end surface and the opening have respective geometric centers that are arranged at a distance from one another, with the at least one pressure relief wave disposed further away from the opening having an interruption of the circular course, through which interruption a connection line of the two geometric centers extends. For example, the metallic end surface and the opening can be rotationally symmetrical, in particular circular, and the respective centers of rotation can form the geometric centers.

The invention also relates to a can end, in particular for beverage cans, in particular as stated above, comprising a metallic end surface that has a first flat side and a second flat side facing away from the first flat side, wherein an opening is formed in the end surface, which opening is bounded by a closed margin of the end surface and 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, wherein a base plane of the closure piece is defined by the course of the microgap, wherein a first end region of the closure piece is connected to the surrounding end surface via a pivot bearing; and a tear-open member that is arranged at the first flat side and that engages at a second end region of the closure piece, said second end region being opposite the pivot bearing, so that a pivoting of the closure piece out of the base plane in the direction of the first flat side is made possible by pulling at the tear-open member, wherein the microgap is interrupted between the first end region and the second end region by at least two holding webs via which the closure piece and the surrounding end surface are connected to one another in a bonded manner.

The more and the wider the holding webs are, the more stable the closure piece is seated in the opening. However, a stable fit of the closure piece makes the initial opening more difficult. As mentioned above, it is challenging to simultaneously ensure an easy initial opening and a sufficient stability at elevated pressure.

To solve this problem, according to one aspect of the invention, an elongate elevated portion is embossed into the closure piece, said elongate elevated portion rising above the base plane in the direction of the first flat side and extending transversely to a line that extends through two of the at least two holding webs and through the elongate elevated portion.

If the can end bulges upwards as a result of a pressure increase in the can, the central region of the closure piece moves upwardly first. The elevated portion has a stiffening effect and, due to its shape and orientation, ensures like a lever that the upward movement of the central region is accompanied by a downward movement of the marginal region. A virtual axis of rotation is therefore formed that extends parallel to or coincides with the connection line between the two holding webs. The transition between the closure piece and the surrounding end surface is thereby relieved and an unwanted drifting apart of the metal margins at the microgap is avoided. It has been shown that, due to the effect of the elongate elevated portion, it is possible to move the holding webs further back from the point of engagement of the tear-open member overall than was previously possible. Such a setting back is in particular advantageous due to the improved venting effect.

The elongate elevated portion can extend, starting from the second end region, in the direction of the first end region. This means that the elongate elevated portion can extend, starting from the point of engagement of the tear-open member, in the direction of the pivot bearing. When the can end bulges upwards, the region of the tear-open point is particularly relieved. This is advantageous insofar as the holding webs should be as far away as possible from the tear-open point due to the venting and this region is therefore particularly susceptible to pressure loads.

A further embodiment of the invention provides that the opening has a geometric center and the elongate elevated portion has a longitudinal axis that extends through the geometric center of the opening. This ensures a particularly favorable relief effect.

The elongate elevated portion preferably has, with respect to the base plane, a height that is at least as great as the thickness of the metallic end surface and at most four times the thickness of the metallic end surface, with the height of the elongate elevated portion particularly preferably being at least one and a half times the thickness of the metallic end surface and at most three times the thickness of the metallic end surface. Such a height has proven to be particularly favorable for common applications.

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

Provision can be made that the opening has a rounded hexagonal shape and the elongate elevated portion extends, starting from a corner region of the opening, in the direction of an opposite corner region of the opening. The elongate elevated portion can in particular extend starting from a corner region that coincides with the second end region. A tearing open at the corner enables a particularly favorable venting. The elevated portion simultaneously ensures that the closure piece does not come loose prematurely at the corner. The rounded hexagonal shape of the opening is advantageous in that the provision of the holding webs at the straight sections is particularly simple.

The elongate elevated portion can have a club shape. This enables a particularly favorably graduated stiffening effect.

According to a specific embodiment, the elongate elevated portion has a head section close to the margin and a tail section that is narrowed with respect to the head section. It has been shown that a particularly pronounced stability increase is desirable in the region of the margin.

The tail section can be tapered, preferably continuously, in a direction facing away from the head section. The stiffening effect then decreases away from the tear-open point, which has proven to be particularly advantageous.

The invention furthermore relates to a can end, in particular for beverage cans, in particular as stated above, comprising a metallic end surface that has a first flat side and a second flat side facing away from the first flat side, wherein an opening is formed in the end surface, which opening is bounded by a closed margin of the end surface and 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, wherein a first end region of the closure piece is connected to the surrounding end surface via a pivot bearing; and a tear-open member that is arranged at the first flat side and that engages at a second end region of the closure piece, said second end region being opposite the pivot bearing, so that a pivoting of the closure piece out of the base plane defined by the opening in the direction of the first flat side is made possible by pulling at the tear-open member, wherein 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.

To solve the initially mentioned problem, according to a further aspect of the invention, a closure relief bead is embossed into the closure piece and extends along the margin of the opening at least past the at least one holding web.

In the event of a pressure increase in the can, the holding web is decoupled from the central region of the closure piece by the closure relief bead and is thus protected against an unwanted overloading. A stretching of the end surface is compensated by the closure relief bead so that an overloading or even a breaking of the holding web does not occur.

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

Provision can be made that the microgap is interrupted between the first end region and the second end region by a plurality of holding webs via which the closure piece and the surrounding end surface are connected to one another in a bonded manner, with the closure relief bead extending past all the holding webs and being curved away from the margin in the region of each holding web. Thus, all the holding webs are protected from an overloading.

The closure relief bead is preferably curved toward the margin in the region between two consecutive holding webs. This enables the formation of a closed peripheral closure relief bead despite the curvatures facing away from the margin in the region of the holding webs.

A further embodiment of the invention provides that the closure relief bead has, with respect to the base plane, a height or depth that is at most one and a half times the thickness of the metallic end surface, with the height or depth of the closure relief bead preferably being at most as great as the thickness of the metallic end surface. This has proven to be particularly favorable with common end designs.

The closure relief bead preferably has a first flank facing the margin of the end surface and a second flank facing away from the margin of the end surface, with the second flank being steeper than the first flank. This results in a particularly favorable relief effect.

A combination of a pressure relief wave as described above with an elongate elevated portion as described above and/or the closure relief bead has proven to be particularly advantageous. The aforementioned relief features can in particular have a graduated effect. For example, in the event of a moderate pressure increase, only the pressure relief wave can initially start to function and the holding web can be protected by the closure relief bead only when a higher threshold value is exceeded.

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

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in the following by way of example with reference to the drawings.

FIG. 1 is a plan view of a can end according to the invention in a closed state;

FIG. 2 shows the can end in accordance with FIG. 1 without closure components;

FIG. 3 shows a closure piece of the can end in accordance with FIG. 2 in an individual representation;

FIG. 4 shows a cross-section through the closure piece of FIG. 3 along the line A-A; and

FIG. 5 shows an arrangement of pressure relief waves of the can end in accordance with FIG. 1 in a cross-sectional view.

DETAILED DESCRIPTION

FIGS. 1 and 2 show a can end 11 designed according to the invention that is intended for a beverage can or the like and that has a metallic end surface 13. The metallic end surface 13 has a first, here an upper, flat side 16 and a second, here a lower, flat side 17 (FIG. 4) facing away from the first flat side 16 and is preferably formed from a sheet metal layer composed of aluminum or tinplate. The metallic end surface 13 preferably has a uniform thickness of 0.1 mm to 0.3 mm, preferably of approximately 0.2 mm. A coating composed of plastic material can be applied to the second flat side 17 of the metallic end surface 13. In the embodiment shown, the metallic end surface 13 is circular in the plan view and has a circle center 20. The can end 11 can be connected to a beverage container via a beaded rim 18 of the metallic end surface 13.

An opening is provided in the metallic end surface 13 and, in the shown delivery state of the can end 11, is closed by a section of the metallic end surface 13 in the form of a closure piece 19. As can be recognized in FIG. 2, the closure piece 19 is separated from the surrounding end surface by a border in the form of a microgap 21. The microgap 21 extends within a plane and defines the base plane 23, recognizable in FIG. 4, of the can end 11. As shown, the opening is arranged off-center in the metallic end surface 13, i.e. the geometric center of the opening is spaced apart from the circle center 20.

The can end 11 comprises a sealing frame, not recognizable in the Figures, composed of plastic material that surrounds the opening and that is fixedly connected to the metallic end surface 13. A closure unit 29 composed of plastic material and supporting the closure piece 19 is further provided and is pivotably connected to the sealing frame via a pivot bearing 30. A releasable fluid-tight connection between the sealing frame and the closure unit 29 is made possible by means of a latch device, not shown, that is formed by sealing and latching ribs and associated reception grooves. The can end 11 is therefore reclosable.

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

The closure piece 19 is individually shown in FIG. 3. 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 surrounding end surface via the pivot bearing 30 (FIG. 1) and the sealing frame, while the ring-shaped tear-open member 29 engages at a second end region 62 of the closure piece 19, said second end region 62 being opposite the pivot bearing 30, via the closure unit 29. The two end regions 61, 62 are located at oppositely disposed 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 microgap 21 is interrupted by a total of six holding webs 65 via which the closure piece 19 and the surrounding end surface are connected to one another in a bonded manner. A connection line 67 extends through the two front holding webs 65, i.e. the holding webs 65 disposed closest to the second end region 62.

When opening the can for the first time, a user pulls at the tear-open member 37 and thereby upwardly pivots the closure unit 29 with the closure piece 19. In this respect, the latch connection between the closure unit 29 and the sealing frame is released.

Due to the holding webs 65, only a relatively small opening is produced in the end surface 13 at the start of the pivoting process, said opening extending starting from the second end region 62 up to the region of the two front holding webs 65, i.e. approximately up to the connection line 67. The holding webs 65 at least briefly counteract a further opening. The relatively small opening in the environment of the second end region 62 provides a venting of the can. In the further course of the initial opening process, the holding webs 65 tear one after the other. The closure piece 19 can then be pivoted completely upwardly to release the entire opening. Due to the opening graduated by the holding webs 65 and the associated venting effect, no significant spraying, popping or foaming over occurs in this respect.

A support nub 31 comprising a planar support section 33 is embossed into the closure piece 19. The support nub 31 of the closure piece 19 is similar in shape to three further support nubs 34, 35, 39 (FIG. 1) that are embossed into the region of the metallic end surface 13 surrounding the opening. All the support nubs 34, 35, 39 have the same height 50 (FIG. 4).

Three embossed pressure relief waves 77, 78, 79 (FIG. 2), which extend parallel to one another at least partly around the opening, are provided to prevent excessive material stresses in the event of a pressure increase in the can. Specifically, the radially innermost pressure relief wave 77 has a closed circular course with the geometric center of the opening as the circle center. The middle pressure relief wave 78 and the radially outermost pressure relief wave 79 have respective arcuate courses with the geometric center of the opening as the circle center, but are not peripherally closed. Rather, the middle pressure relief wave 78 and the radially outermost pressure relief wave 79 are interrupted, with the respective interruptions 80 being arranged such that they occupy a position closest to the beaded rim 18. The interruption 80 of the radially outermost pressure relief wave 79 is, as shown, preferably longer than the interruption 80 of the middle pressure relief wave 78. For example, the middle pressure relief wave 78 can extend over an angle of approximately 300° and the radially outermost pressure relief wave 79 over an angle of approximately 250°.

The pressure relief waves 77, 78, 79 are shown in cross-section in FIG. 5. Each pressure relief wave 77, 78, 79 comprises a wave trough 81 having a curved cross-section and extending transversely to the base plane 23. Between the wave troughs 81, there are wave peaks 82 that likewise have a curved cross-section. It is preferred that the depth of the wave troughs 81 with respect to the base plane 23 is at least as great as the thickness of the metallic end surface 13 and is at most twice the thickness of the metallic end surface 13. As can be seen in FIG. 5, the magnitudes 85, 86, 87 of the depth of the wave troughs 81 related to the base plane 23 increase toward the opening, i.e. from the outside inwards.

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

Further relief is achieved by an elongate elevated portion 36 that is embossed into the closure piece 19 and that rises above the base plane 23 in the direction of the first flat side 16, i.e. upwardly in the embodiment shown. The elongate elevated portion 36 has a longitudinal axis 70 that is oriented transversely to the connection line 67. Furthermore, the elongate elevated portion 36 has a club-like shape with a head section 89 close to the margin and a tail section 90 that is narrowed with respect to the head section 89 close to the margin. The tail section 90 is continuously tapered in a direction facing away from the head section 89. The head section 89 is arranged in the second end region 62 so that the elongate elevated portion 36 extends, starting from the second end region 62, in the direction of the first end region 61.

When the can end 11 bulges upwards as a result of a pressure increase in the can, the central region of the closure piece 19 moves upwardly first. Due to the stiffening effect of the elevated portion 36, this movement of the central region is accompanied by a downward movement of the second end region 62. That is, the part of the closure piece 19 facing the second end region 62 pivots about the connection line 67, whereby the transition between the closure piece 19 and the surrounding end surface is relieved in the environment of the second end region 62.

Furthermore, a closure relief bead 38 is embossed into the closure piece 19 and extends along the microgap 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 elongate elevated portion 36. In the embodiment shown, the closure relief bead 38 is peripherally closed and is alternately curved away from the microgap 21 and toward the microgap 21. The sections 95 curved away from the microgap 21 are located next to the holding webs 65 and merge between the holding webs 65 into sections 96 curved toward the microgap 21. A flower-like pattern of the closure relief bead 38 thereby results in the plan view. At the second end region 62, the closure relief bead 38 merges into the head section 89 of the elongate elevated portion 36.

It is preferred that the closure relief bead 38 has, with respect to the base plane 23, a depth that is at most as great as the thickness of the metallic end surface 13. The outer flank facing the margin 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 holding webs 65 are decoupled from the central region of the closure piece 19 by the closure relief bead 38 and are thus protected against an unwanted overloading.

The invention provides a reclosable can end 11 that is easy to open even during the initial opening and that nevertheless meets all the stability requirements for a pasteurization and storage of the can.

REFERENCE NUMERAL LIST

• • 11 can end
  • 13 metallic end surface
  • 16 first flat side
  • 17 second flat side
  • 18 beaded rim
  • 19 closure piece
  • 20 circle center
  • 21 microgap
  • 23 base plane
  • 29 closure unit
  • 30 pivot bearing
  • 31 support nub
  • 33 planar support section
  • 34 support nub
  • 35 support nub
  • 36 elongate elevated portion
  • 37 tear-open member
  • 38 closure relief bead
  • 39 support nub
  • 50 height of the support nubs
  • 61 first end region
  • 62 second end region
  • 65 holding web
  • 67 connection line
  • 70 longitudinal axis
  • 77 inner pressure relief wave
  • 78 middle pressure relief wave
  • 79 outer pressure relief wave
  • 80 interruption
  • 81 wave trough
  • 82 wave peak
  • 85 depth of the outer wave trough
  • 86 depth of the middle wave trough
  • 87 depth of the inner wave trough
  • 89 head section
  • 90 tail section
  • 95 section curved away from the microgap
  • 96 section curved toward the microgap