EP1843946B1 - Stackable flat bottomed can - Google Patents

Abstract

The invention seeks to provide the possibility of producing alternately (according to need) on the same production line beverage cans which are in one piece in the body portion and alternatively thereto metal cans for in particular baby food or children's food, milk foods or evaporated milk, while at the same time affording the possibility of considerable material savings on the last-mentioned food sector. Proposed for that purpose is a metal can comprising a seamless can body of sheet metal comprising a can body portion and a substantially flat bottom formed in one piece therewith, wherein the body portion is drawn conically inwardly both towards the bottom and also towards its open end respectively. The substantially flat bottom has an outwardly facing bead or indentation for stackingly receiving a connecting seam which connects one end of the can body portion of a second identical metal can to the lid thereof.

Description

The invention relates to a metal can made of steel or aluminum, preferably of smaller format, as is customary for baby or infant formula or condensed milk. The metal box is a one-piece box from the sheet types mentioned, with the second Tell a lid added, which is attached with a fold on the upper edge of the box (more precisely, the fuselage or lower part or seamless can body).

Metallic containers or cans were generally made of three parts (so-called three-cell cans) for the stated purposes: a hull rolled out of sheet metal with a longitudinal seam connecting the axially extending end edges and a bottom and a lid connected respectively to the open ends of the hull a double seam were connected. Although the production is simple and inexpensive, but material-consuming.

There are metal cans also already made in two parts and especially used as beverage cans For this, the hull and the bottom is made in one piece by stripping (DWI method) and only the lid folded in the usual way. The production is much more difficult and expensive, but much cheaper in terms of material consumption. Because of the difficulties and costs of production, this type of manufacturing is mainly used in the field of high-volume beverage cans, which due to the specialization on beverage cans an existing production line is sometimes not sufficiently utilized

From the GB 1 572 031 is a metal can, in particular a beverage can according to the preamble of claim 1, known, which is stackable. In such a beverage can is a bulge, which also forms the footprint of the beverage can, provided on the bottom of the respective beverage can. This convexity with an outer cone is capable of sliding into the skirt of the lid of a lower can located under an upper can and thus making a stack connection between the upper and lower cans.

A solid stacking is not possible with such doses.

From the EP 1 103 470 A1 If a metal can with a high-pressure control element is known, the geometric shape of the bottom of this can is aimed at the pressure resistance of the can with regard to high internal pressures. A stackability, in particular with regard to the stack of two cans by means of a correlation between connecting seam and a bead, goes out of the EP 1 103 470 A1 not apparent.

With the invention, the possibility is to be created, and therein the invention sees its technical task, on the same production line alternately (also according to demand) in the fuselage one-piece beverage cans, alternatively metal cans for baby or baby food in particular, milk formula or condensed milk, while at the same time In the last mentioned food sector, the possibility of significant material savings should be opened up.

This object is achieved according to claim 1 or also for the stacking state according to claim 20 and 21. The essence of the production process of the metal can from the manufacture of beverage cans is taken over, so that the production can be done on the same production line. However, in particular, the bottom shape is adapted to the other use and then optimized for optimal utilization the volume of space is possible. In addition to a maintained stability and easy and safe stackability of the doses according to the invention is achieved (claim 1, claim 25).

The object is also achieved by alternative uses (claim 26, claim 27) of the filled can according to claim 1 or claim 20. Preferably, condensed milk is a foodstuff as non-carbonated contents for the open can according to claim 1 or the closed can according to claim 20.

The bottom of the can is - in contrast to on the priority day common two-piece beverage cans - designed to be substantially flat. He has no concave or convex curvatures (claim 4). Thus, the filling volume of the small-volume can bodies essentially corresponds to the schematic volume of space of the can (as a cylinder body), which is thus completely available for the filling.

To achieve the dimensional stability, an inert gas can be filled in during the filling of the can and thus a slight internal overpressure can be generated.

A preferred "slight overpressure" is in the range of 0.1 MPa (1 bar), in addition to the external pressure, preferably between 0.8 bar and 1.2 bar over the external pressure, generally assumed to be 1 bar (0.1 MPa) is (claim 22), all at normal outdoor temperature. This should be understood as "easy". This can be seen in relation to the high pressures that can be obtained with carbonated beverage cans between 0.4MPa (4 bar) and 0.8MPa (8bar) in addition to pressure, which a domed vaulted soil can withstand.

The claimed metal cans are small volume (claim 18), but may have different dimensions in terms of axial height, diameter and opening width at the trunk end. Their volume is in the meaning of a "smaller format" in the range between 150ml and 500ml, ie below half a liter, preferably below 330ml. Their height is usually no larger than 120mm, their diameter between 50mm and 75mm.

The axial extent of the conical sections (in the understanding of a portion of a cone, so formed as a truncated cone, but quite "conical") above and below may vary, but they are clearly visible. An area in which the clearly visible conical shapes are dependent on the diameter of the can body. He but can be summarized. Above is the cone angle angle in the range of 30 ± 20% settle (claim 15). Below the conical surface is inclined in the range between 10 ° and 30 ° (claim 14), each corresponding axial length to allow stacking.

The claimed for the stiffening of the substantially flat bottom surface possibilities for increasing the ground stiffness (claim 5,6,7) can also be replaced by fine ribs or grooves or the like. It is essential that the bottom surface is substantially flat (free of bulges). But he may have staggered annular shoulders as several stages (claim 7).

The floor is stiffened to the extent that an everting to prevent the stability and to block a stackability is avoided. The bottom is still flat, which does not allow it to extend further upward than measured from the support plane, as substantially 5 mm (claim 8). It extends in a height range between the contact plane and the highest point of the bottom surface, usually in the central portion of the bottom, which does not extend further than an intended stacking bead, which is arranged radially within the circumferential Aufstandsrippe (claim 6).

Despite the relatively flat shape of the soil, it is pressure stable, but not to the extent, as a dome-shaped curved bottom. Its pressure stability against evagination or bulging extends to substantially 2 bar, in particular to 3.5 bar (claim 16). For this purpose, sheet thicknesses of the soil are in steel sheet in the range between 0.2 mm and 0.25 mm (claim 17).

The soil stiffness is adapted to the intended use. A terraced formation (claim 9) can be chosen as well as a central planar area which is surrounded by annular corrugations (claim 10).

The method for stacking the seamless can body (claim 21) can also be understood as relating to the manufacture of these can bodies. A substantially flat bottom is integrally formed. In each case to the axial end of the can is a conical confinement, both in the lower portion and at the upper end portion. The substantially flat bottom connects to a further outermost bead, which can be named as stacking bead. In the stacking state or stacking, an underlying seam of a second can, which is identical or structurally similar (possibly with different imprint and decoration), engages. stacking one. The same task is fulfilled by the circumferential indentation in the conical confinement, which can be understood as a laterally open groove and can create a folded seam within the inner edge.

A substantially flat cover mirror of a folded lid is lowered relative to the connecting seam and immediately adjoins this seam via a chuck wall projecting axially towards the interior of the fuselage or the closed container (claim 11). The reduction is small. Your measure is smaller than the axial height of the fold (claim 12).

The lid is designed as a tear-open lid with a peripheral line of weakness and a pull-tab, preferably as a full-open lid with round line of weakness near the damping bead (claim 13).

When stacked, the bottom bead axially inwardly (to the interior of the sealed container) disposed radially inwardly of the lower end of the cone-shaped retraction of the fuselage has a seam stacking contact associated with a can underneath. The lower end of the recovery forms the rib (claim 2).

What applies to the towering bottom bead of the above-mentioned fuselage is correspondingly applied to the radially further outward circumferential indentation (as indentation) in the region of the frustoconical constriction of another hull (claim 3).

The circumferentially extending indentation is directly attached radially to the outside of the recess. It is the radially outwardly facing wall or surface of the fin (claim 3), which is formed radially inward and thus "outwardly facing".

Preferably, the upstanding bottom bead or circumferential indentation, while maintaining the axially downwardly extending rib, extends directly from or is at least close to it.

Further advantageous features / properties can be found in the dependent claims and are also explained in connection with the following description of several embodiments.

Figur 1

in schematischer, die Achse 100 der Dosen enthaltender Schnitt-Darstellung eine Form der neuen Metall-Dose an einem ersten Ausführungsbeispiel, kurz vor einem Stapeleingriff.

Figur 2

In ähnlicher Darstellung eine der Dosen nach Figur 1 In noch nicht verschlossenem Zustand. Der Boden. 3 ist derselbe.

Figur 3

in perspektivischer Ansicht den Boden 3 der Metalldose nach Figur 1.

Figur 4

In ähnlicher Darstellung wie Figur 2 ein abgewandeltes Ausführungsbeispiel.

Figur 6

In gleicher Darstellung wie In Figur 4 eine weiter abgewandelte Ausführung.

Further features are explained in more detail in connection with the following description of several embodiments. The accompanying figures show

FIG. 1

in a schematic, the axis 100 of the cans containing sectional view of a shape of the new metal box to a first embodiment, just before a stacking engagement.

FIG. 2

Similarly, one of the doses after FIG. 1 In not yet closed condition. The floor. 3 is the same.

FIG. 3

in perspective view the bottom 3 of the metal can after FIG. 1 ,

FIG. 4

In a similar representation as FIG. 2 a modified embodiment.

FIG. 6

In the same representation as In FIG. 4 a further modified version.

The basic form of metal cans, 1,1 a or 16 made of sheet metal after FIGS. 1 to 3 has a seamless hull 2 with integrally formed bottom 3. The hull 2 is tapered at its two end regions (at the upper edge a so-called. Necking, at the bottom of a confiscation to a circumferential ribs). The cone shape is shown at 5 or 11 at the respective axial end region.

The open end 17 of the fuselage 2 can be closed with a metallic cover 4 via a double seam in a conventional manner. As a result, the upper closed axial end 2b forms. The production of hull and ground is done in the usual way by drawing (drawn wall ironed, DWI) and brings a significant material savings, as is known from two-piece beverage cans ago. The cover 4 has a "mirror" as a cover panel 4a and a circumferential damping bead 13, which leads into the connecting seam 12 (as, for example, fold). The panel 4a is substantially flat and is lowered from the upper end of the seam 12 and immediately adjoins this seam 12 via the axially downwardly extending bead 13.

The can bottom 3 is - in contrast to the priority day common two-piece beverage cans - formed substantially flat. It has no concave or convex curvature. Thus, the filling volume essentially corresponds to the schematic volume of space of the can, which is so fully available for the filling.

At the lower end of the conical confinement 5 of the hull 2 is immediately followed by an axially outwardly projecting rib 6 of small radius of curvature 6a. The bottom sections lying radially within this rib 6 lie at a small distance above the contact surface E formed by the rib. Immediately following the counter-rib 6, there is an axially open bead 7 on the radial inner side thereof. This is - with respect to position and shape of the seam 12 between the opening edge of the fuselage 2 and the lid closing the opening - arranged and dimensioned so that the seam 12 of another, similar can when stacking the metal cans securely received in the bead 7 which contributes to easy and safe stackability. The axial alignment of seam 12 and bead 7 symbolizes the line Y.

This ring plane defined by Y is based on the upper can 1 and the similar lower can 1a. However, it is equally representative of the bead 7 and seam (seam) 12 'on the same can 1. 12 'symbolizes the folding seam, not shown, on the upper box 1. As such, it can also be measured alone as stackable if it is placed in a stack composite with "its like", as is the beginning of the stacking state FIG. 1 shows. This applies in the same way also to the later presented examples of Figures 4,5 ,

The bottom area within the bead 7 is terraced and consists of the flat central surface 8 and two likewise flat annular surfaces 9 and 10, which are connected via small steps or shoulders 9a, 10a with each other. The step heights are smaller than the horizontal extensions of the ring surfaces.

Overall, this results in a substantially flat structure of the bottom 3, which has no inwardly projecting bulges. Neither that appear in the center as a dome-shaped bulge, nor those that are distributed over the ground distributed dome-shaped individual curvatures in a composite of several such vaults.

The substantially flat bottom extends in height direction only limited, which explains its small distance from the fin 6. The riot level E is defined by the lowest point of the fin 8, which runs around the stacking bead 7. The small radius of curvature 6a defines the arc defining the axially lower end of the fin 6 thereof. Spaced axially (and radially as well) is the central area 8. These two dimensions define the height range of the floor which is still referred to as "substantially flat "is considered.

This height range or difference height is not higher than 10 mm, preferably less than 5 mm, measured from the level E (the lower axial end of the fin) and the highest point of the bottom 3, which is In FIG. 1 the central area 8 corresponds.

The thickness of the sheet used In this soil is between 0.2 mm and 0.25 mm for steel cans. The bottom is designed, despite the absence of dome-shaped stiffeners, to withstand an internal pressure ranging up to 3.5 bar (0.35 MPa), which is the differential pressure between the internal pressure of a sealed and filled can and the external pressure below the bottom.

This compressive strength refers to a resistance to evasion or buckling, slight variations in the heights of the sections of the terraced floor are quite permitted, the standing and stacking ability must not be affected, however, the maximum movements of the substantially flat soil at its low Height dimension circumscribes. This naturally implies that the bottom also remains stabilized up to essentially 2 bar (0.20 MPa), ie neither evades nor bulges even at lower pressures, based on the same pressure difference, which was called the 3.5 bar number.

The metal cans are small-volume, may have different dimensions with respect to the axial height 15a, diameter 16b and opening width 15c at the fuselage neck 17 (axial upper end). Their volume is preferably in the range between 150ml and 500ml. Their height is usually not greater than 120 mm, their diameter between 50mm and 76 mm. Also, the axial extent 6c of the conical recess 5 of the fuselage 2 at the transition to the ground area can vary as well as the Kegeineigung 6b.

The Kegeineigung refers to the axially lower end of the can. It lies in an indicated angle 6b, which can be selected between 10 ° and 30 °, depending on the diameter 15b of the can body. The Kegenelgung at the opposite end, symbolizes with 11 in FIG. 1 (in the case of the axially lower can), lies above the angle message at the lower end and is 30 ° with a margin of ± 20%.

To achieve dimensional stability, the can may be provided with the food after filling or with an inert gas when filling, which produces a slight internal overpressure. A preferred "slight overpressure" is in the order of 1 bar (0.1 MPa), in addition to the external pressure, preferably between 0.8 bar and 1.2 bar over the external pressure, which is generally assumed to be 1 bar. The associated wall thickness of the fuselage 2 is in the range between 0.07 mm and 0.09 mm sheet thickness, especially in steel.

FIG. 4 shows a modified configuration 3a of a bottom portion within the immediately adjacent to the conical surface edge bead 6 of a can 20. Again, the central portion 22 is smooth and flat. The section 21 between this and the edge bead 6 is weakly wavy or zig-zag-shaped in cross section, which in turn connects to the edge bead an outwardly open bead 7, In the - as indicated - the folded seam on the lid 24 of the underlying can is included. On the cover serving for opening grip tab 25 is attached. It can be seen that this bottom 22 is formed substantially flat, without convex or concave bulges. The wavy portion 21 has a plurality of circumferentially extending recesses 23, but which are not a convex / concave bulge in the sense of a dome (Dom) or an eccentric bulge. The amplitudes of the recesses are smaller than the depth of the bead 7. The box 20 has at the upper open end a conical recess 41 with a substantially flat inclined surface. At the fuselage neck 47, a lid can be folded, as a lid 24 in FIG. 4 shown.

The container 30 according to Figure 6 has an inner bottom surface 35, that of the bottom 3a after FIG. 4 equivalent. Immediately radially Within the ridge bead 36 of the can, as described above, there is an outwardly open bead 38 for possible reception of the seam of another can.

In this embodiment, on the radial outer surface of the standing bead 36, ie in the region of a conical recess 31, a dent 32 (as a peripheral open bead) is provided, which is arranged and dimensioned so that they provide the provided at the upper end 30b seam 34 between the cover 33rd and can securely hold a lower can 30a with a larger lid diameter.

The circumferential indentation 32 on the radially outer surface of the ridge bead 36 may be present alone or in addition to the peripheral bead 38, the latter the bead 7 corresponds to the previous examples. The ratio of the recesses 41, 31 determines which lid size of a lid 33 is used to achieve stacking. Either by engagement of the seam 34 in the radially outward indentation or by engagement in the radially inwardly located bead 38 (corresponding to 7 of the other examples). Both, the bead 7 and 38 on the one hand and the indentation 32 on the other hand are "pointing outwards". They can be individual or cumulative.

The possibilities of increasing the soil leakage, which are indicated for the hardening of the inner floor area, can also be replaced by fine ribs or grooves or the like. The floor still remains essentially flat and free of bulges, which is referred to as a "dome-shaped" concavity in a beverage can.

The comments made on the previous embodiments on the addition of inert gas under pressure to stabilize the wall, the sheet thicknesses, the low height of the substantially flat bottom, the dimensions of the conical recoveries and the pressure stability of the soil are on the Executions of the FIGS. 4 and 5 transfer accordingly. These apply here as well.

Not shown in the drawings are score lines in the lid of a respective lid 4, 24 or 33. They are familiar to the expert and are used to open the lid, so that they are not shown in the drawing. A respective lid has as a tear-open while a circumferential line of weakness, with the tear tab 25 after FIGS. 4 or 5 can be broken to take out the lid sponge within the circumferential line of weakness. This is common and common prior art, which will not be explained separately here.

Claims (21)

1. A metal can comprising a seamless can body (1) of sheet metal having a can body portion (2) and a - substantially flat - bottom (3; 3a; 35) formed in one piece therewith, wherein
   the body portion (2) is drawn conically inwardly (5, 11; 31, 41) both towards the bottom (3) and also towards an open end (15c) respectively and
   the substantially flat bottom (3) has an outwardly facing bead (7) or indentation (32),
   characterised in that it is adapted and suitable for stackingly receiving a connecting seam (12; 34) which connects an end (15c) of a can body portion of a second identical metal can (1a; 15) to the lid (4) closing it.
2. A metal can according to claim 1 wherein the axially inwardly projecting bottom bead (7) is arranged radially within the lower end of the conical inwardly drawn portion (5) of the body portion (2) and - preferably forming an axially outwardly projecting support rib (6) - starts from the conical inwardly drawn portion (5) or is at least near thereto.
3. A metal can according to claim 1 wherein the indentation (32) is provided in the region of the conical inwardly drawn portion (31) of the body portion (30) radially outside an axially outwardly projecting support rib (36) directly adjoining the inwardly drawn portion.
4. A metal can according to one of the preceding claims wherein the

   - substantially flat - bottom (3) is free from convexly or concavely curved bottom portions.
5. A metal can according to one of claims 1 to 4 wherein the - substantially flat - bottom (3) comprises a plurality of radially mutually displaced, substantially flat bottom surface portions (8, 9, 10).
6. A metal can according to one of the preceding claims wherein the flat bottom (3; 3a; 35) extends in a heightwise region which is defined by an axially upper end of the bead (7) and an axially lower end of a support rib (6), in particular in a heightwise region of less than 5 mm.
7. A metal can according to claim 5 wherein the bottom surface portions are respectively connected together by way of narrow shoulders (9a, 10a) or the like steps, in particular the 'narrow shoulders' are shorter than a lateral extent of a respectively adjacent bottom surface portion, which represents a slight stepping.
8. A metal can according to claim 5 wherein the bottom (3; 3a; 35) does not project axially inwardly higher than 5 mm, measured from a lower axial end of a support rib (6, 36).
9. A metal can according to claim 5 wherein the flat bottom surface portions (8, 9, 10) are displaced relative to each other in the axial direction by way of shoulders (9a, 10a), preferably in an axially inward direction when viewing from radially outside to radially inside.
10. A metal can according to one of claims 1 to 9 wherein the substantially flat bottom (21), outside a bottom center (22; 8), has annularly extending corrugations (23) or the like, in particular of a slight amplitude.
11. A metal can according to one of the preceding claims wherein a substantially flat lid panel (4a, lid plate portion) is lowered with respect to the connecting seam (12) and directly adjoins said seam by way of an axially inwardly projecting damping bead (13).
12. A metal can according to the preceding claim wherein the lowering in relation to the connecting seam is slight, in terms of heightwise dimension less than an axial height of a double fold configuration (12).
13. A metal can according to claim 1 or claim 6 wherein the lid (4; 24) is in the form of a tear-open lid with a peripherally extending weakening line and a tear-open tab (25) and the first and second metal cans are in mutually stacked relationship, wherein the connecting seam (12; 34) which connects the tear-open lid to the second metal can is stackingly received.
14. A metal can according to claim 1 wherein the conical inwardly drawn portion (5) is between 10° and 30° relative to the bottom (3).
15. A metal can according to claim 1 or claim 14 wherein the conical inwardly drawn portion (11, 41) is in the range of 30° ± 20% towards the open end (47).
16. A metal can according to claim 1 or claim 6 wherein the substantially flat bottom has a pressure resistance to being displaced outwardly or to being caused to adopt an outwardly curved configuration, which extends to substantially two bars (0.20 MPa), as a differential pressure in relation to an outside pressure.
17. A metal can according to claim 16 wherein the sheet metal of the substantially flat bottom is between 0.2 mm and 0.25 mm in thickness.
18. A metal can according to one of the preceding claims wherein the receiving volume of the can extends between 150 ml to substantially 500 ml.
19. A metal can according to claim 16 wherein the pressure resistance extends to substantially 0.35 MPa.
20. A method of producing a metal can comprising a seamless can body (1) of sheet metal, having a can body portion (2) and a - substantially flat - bottom (3; 3a; 35) which is formed in one piece therewith,

    - wherein the body portion (2) is conically inwardly drawn (5, 11; 31, 41) both towards the bottom and also towards its open end (17) respectively and the substantially flat bottom acquires an outwardly facing bead (7) or indentation (32), wherein the bead (7) or indentation (32) is adapted to receive a further downwardly disposed connecting seam (12; 34),

    - which seam connects an axial end (17) of a can body portion of a second metal can (1a, 30), which is identical in that respect, to the lid (4, 33) thereof, and

    - the two cans can be stacked.
21. A method of stacking a plurality of metal cans comprising a seamless can body (1) of sheet metal, having a can body portion (2) and a

    - substantially flat - bottom (3; 3a; 35) which is formed in one piece therewith,

    - wherein the body portion (2) is conically inwardly drawn (5, 11; 31, 41) both towards the bottom and also towards its open end (17) respectively and the substantially flat bottom has an outwardly facing bead (7) or indentation (32), wherein the bead (7) or indentation (32) receives a further downwardly disposed connecting seam (12; 34),

    - which seam connects an axial end (17) of a can body portion of a second metal can (1a, 30), which is identical in that respect, to the lid (4, 33) thereof, and

    - the two cans are stacked.

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