EP0236736A2 - Tearable metal cover for cans - Google Patents

Abstract

There is provided a metal tear-open lid, in particular, made of very thin sheet material wherein by means of a U-shaped recess provided in the tear-open starting section the area where the pull-open ring is fastened to the tear-open portion is reliably prevented from bulging like a membrane as the lid is initially broken up.

Description

The invention relates to a tear-open lid made of metal for cans, in particular of an oval or rectangular shape, with the features of the preamble of claim 1.

Such covers are known in numerous embodiments. They can have a circular, a long oval or a rectangular outline with rounded corners. In particular, such covers are widely used as full-opening covers. Here, the score line is arranged close and largely parallel to the core wall of the lid, so that most of the lid mirror is enclosed by the score line and thus essentially the entire cross section of the can can be exposed by removing the tear-open area. As a rule, the tear-open area has a tear-open start section, which is characterized in that the score line in this area deviates from the contour of the cover in order to delimit an area limited by a smaller radius of curvature, in which the score line is initially broken in to open. In this area, the grip tab serving for breaking in and tearing off the tear-open area is mostly fastened flat lying with a rivet molded out of the cover plate.

It is also known to stiffen the lid mirror inside and outside the score line by shoulders, stepped areas, ribs or beads. It is also known to design or orient the ribs or beads in the tear-open section differently than in the part of the tear-open area which is the last to be separated from the lid mirror when the can is opened. In particular, it is known in the case of long oval or rectangular cans tear start section transverse to the longitudinal center line or transverse to the tear direction to provide rectilinear or curved beads, which should facilitate unrolling of the sheet in the tear start section after the initial opening and subsequent pulling off of the tear area from the lid mirror and to avoid barrel-shaped bulging in this area. In the case of circular lids, these beads which extend transversely to the opening direction can continue to the end of the opening area. In the case of long oval or rectangular lids, however, this ability of the tear-open area to bend can be canceled in other areas of the tear-open area by beads oriented differently. In addition to the cross beads, a recess in the tear-open section adapted to the contour of the grip tab has already been provided, which form a coherent stiffening bond with the cross beads, which is additionally supplemented by cup-shaped impressions between this bond and the adjacent score line sections.

It is known that the greatest effort is required to initially break the score line in the starting section. The tearing of the score line after the initial breaking open, however, requires much less force, even if the tearing area must be bent or deformed over its entire width. In order to take into account the comparatively high expenditure of force when the score line is initially broken in, the grip tab is designed as a rigid lever, usually formed from thin sheet metal and stiffened by edge folds or the like. The grip tab can be designed so that the attachment point of the grip tab on the tear-open area is rigidly connected to the rest of the lever-shaped body of the grip tab. However, the arrangement can also be such that the fastening point itself is provided on a bendable fastening section surrounded by the body of the grip tab.

In all of these cases, by lifting the handle end of the handle tab, the score line must be broken in by a shear effect. The forces required are transferred from the grip tab via the fastening rivet to the tab body and from this to the ratchet nose, which generally lies directly above the score line and presses it down. Since the start section of the score line is close to the core wall of the lid, this area ensures that the remaining part of the lid mirror that is permanently connected to the core wall is stiffened in order to withstand this pressure from the breakaway nose of the lever-like grip tab. The resulting shear forces in this area of the score line break the score line.

In many cases it is shown that the shear forces cannot be fully applied to the starting section of the score line, since some of these forces are absorbed in that the pulling action on the fastening rivet deforms the opening section of the opening area upwards, i.e. it yields like a membrane . These disadvantages are particularly noticeable when deviating from the usual sheet thicknesses of 0.24 mm and, in contrast, thinner sheets are used to produce the cover. As the sheet gives way on both sides of the rivet, the breakaway nose moves beyond the score line and loses its effectiveness. This disadvantage is exacerbated by the fact that the sheet is relatively limp in this area due to the embossing of the score line.

It is an object of the invention to develop a tear-open lid with the features of the preamble of claim 1 so that even when using thin sheets, the shear forces generated when lifting the handle end of the grip tab are substantially more complete and thus more effective for initially breaking in the score line under the tab of the grip tab Effect can be brought the disadvantages mentioned should be avoided.

This object is achieved by the measures of claim 1.

In this way, especially in the case of very thin sheets, very good stiffening of a limited area of the tear-open start section containing the fastening rivet is obtained, which largely prevents a membrane-like deformation of this area when the handle end of the handle tab is raised to open the can. Thus, the fastening rivet remains largely in its original position, so that the forces applied via the end of the handle are brought into effect less for the deformation of the tear-open start section, but almost completely for breaking in the score line, the nose remaining in alignment therewith. The cross-sectional shape of the depressions and beads, the expansion of the transverse beads and the straight course of the depression legs contribute significantly to the stabilization of this area.

For this purpose, it is advantageous if the bead-like depression is formed according to claim 2. This ensures that the decisive, limited area of the tear-open section is stiffened to the desired extent, and at the same time the necessary kinking of the extreme end of the tear-open section is promoted when the score line breaks in. In particular, the area in question also has high torsional rigidity.

The further subclaims give further advantageous refinements of the stiffening composite or the U-shaped recess. It is particularly advantageous if the width and / or depth of the two legs of the U-shaped recess are further developed according to claims 3 and 5.

For the desired effect, it is particularly important that the region of the tear-open start section containing the rivet is stiffened like a board, so that here the membrane-like bulging is largely prevented. On the other hand, the area between the fastening point and the starting notch line should be able to be bent down slightly in order to thereby limit the forces required to break in.

The area to be bent down should remain as limited as possible in order to ensure that the score line is torn away safely by applying tensile forces to the grip tab. These requirements are optimally met by the configuration of the beading.

The invention is explained in more detail below with the aid of schematic drawings using an exemplary embodiment.

• Figur 1 einen gemäß der Erfindung ausgebildeten Aufreißdeckel in Seitenansicht,
• Figur 2 den Deckel nach Fig. 1 im Ausschnitt und in Draufsicht,
• Figur 3 den Deckel nach Fig. 1 in Ansicht von unten und
• Figur 4 einen Teilquerschnitt quer zur Längsmittellinie des Deckels.

Show it:

• FIG. 1 is a side view of a tear-open cover designed according to the invention,
• FIG. 2 shows the lid according to FIG. 1 in a detail and in a top view,
• Figure 3 shows the lid of FIG. 1 in a view from below and
• Figure 4 shows a partial cross section transverse to the longitudinal center line of the lid.

It is believed that the lid in question is a long oval lid such as is widely used, e.g. for fish cans. But it could also be a rectangular cover or a circular cover.

The lid is made of sheet metal, preferably from sheets with a thickness that is less than the usual thickness, that is less than 0.24 mm.

The lid is formed in the usual way with a folded edge 2 which merges into the lid mirror 3 via a core wall. A tear-open area 6 is delimited in the cover mirror by a self-contained notch line 7, of which essentially only the tear-open cut 16 is shown in FIG. 2. While in the remaining area of the lid the notch line 7 runs close to the core wall of the lid edge, its course in the area of the tear-open start section 16 deviates from the outline shape of the lid. Rather, the tear-open start section 16 is delimited by two straight-line notch sections 9 converging towards the left end in FIG. In the area of this end, a grip tab 5 is fastened by means of a rivet 4 formed out of the sheet metal. This is designed as a rigid lever and mostly formed from thin sheet metal and stiffened by curling edges and the like. In the illustrated embodiment, the handle flap body is attached directly to the cover plate with the rivet 4 lying flat. However, the grip tab could also be designed such that the fastening point is located on a fastening tab of the grip tab body formed by dividing line 36 in FIG. 2, as is generally known. In the example shown, the grip tab is aligned with its longitudinal center line on the longitudinal center line 19 of the long oval cover. However, a different orientation of the grip tab can also be provided. The grip tab has a front end in the form of a ratchet nose 15, which is arranged substantially flush with the start section 8 of the score line. At the opposite end, the grip tab 5 has a grip section 12, which is ring-shaped in the example shown.

In the further area 17 of the tear-open area 6 adjoining the tear-open start section 16, the sheet is stiffened by recess 20 or by ribs or beads which run parallel to the lid edge or to the notch line section 10 parallel to the latter. The width 39 of the tear-open area here almost reaches the size of the inside width of the can, which can be closed with the lid.

In order to counteract the membrane-like bulging of the tear-open start section when lifting the handle end 12 of the handle tab 5 to open the can, a U-shaped bead-shaped depression 23, 24 is provided near the attachment point 4 and below the handle tab 5. This consists of a web-shaped section 23 lying under the handle section 12 and two legs or arms 24 projecting forwardly towards the starting score line 8, which end abruptly at 26 on a common line 28 transverse to the longitudinal center line 19 of the handle tab 4. The line 28 runs tangentially to the shank 4a of the rivet 4. The web-shaped section 23 is formed in alignment with the handle end 12. In the case of the ring-shaped design of the handle end 12, the web-shaped section 23 also has a corresponding partially ring-shaped course, the width of the bead 23 corresponding to the width of the ring region 12.

The legs 24 can widen in the transition region to the web-shaped section 23. Their width decreases steadily in the direction of the free ends 26. It could also decrease in depth in that direction. The legs 24 run with their inner boundaries 29 straight and parallel to the line 19. The U-shaped recess 23, 24 is combined with beads 21, 22 extending transversely to the longitudinal center line of the grip tab to form a bead assembly. All beads of this bead composite have essentially the same depth. The shorter cross bead 21 intersects the U-shaped recess at the level of the transition between the web 23 and the legs 24, while the longer transverse bead 22 cuts the annular web part 23, as can be seen from FIG. 3. The transverse beads 21, 22 formed in a straight line in FIG. 2 can also be slightly curved. Between the transverse beads 21, 22, a raised region 25 of an almost semicircular contour remains within the ring opening of the handle end 12. Between the shorter bead 21 and the two legs 24 there remains a plateau 11 in the plane of the cover mirror 3, on which plateau the fastening rivet for the grip tab 4 is provided. The transverse beads 21, 22 each project directly up to the adjacent score line sections 9. The remaining distance 31 corresponds somewhat to the width 34 of the beads.

The arrangement can be such that at least part of the handle end 12 engages at least partially in the depth of the beads by the type of attachment of the handle tab 5 or by slight deformation of the handle tab 5, so that the handle at the same time prevents twisting by the arrangement Attachment point is reliably secured. Furthermore, the arrangement and location of the handle end 12 relative to the longer transverse bead 22 can be such that the fingernail or fingertip can be easily gripped under the outermost handle end 12 of the handle tab in order to raise this handle end 12 and open the can. The sealant in the cover flange 2 is designated by 32 in FIG. 3.

At least the legs 24, in the preferred example according to FIG. 3 also the web sections 23 and the transverse beads 21, 22 have an approximately trapezoidal cross section as shown at 30 in FIG. 4.

Claims (7)

1. tear-open lid made of metal for cans, in particular of longitudinal oval or rectangular outline, in which a tear-open area is delimited by a score line in the lid mirror with a tear-open start section, to which a lever-like grip tab is fastened so that its tear-open nose lies above the score line section delimiting the tear start section, wherein the grip tab has a grip section at the end facing away from the tear-open nose, and in which beads and a depression approximately adapted to the shape of the grip tab are provided in the tear-open start section, which form a coherent stiffening group in the tear-open start section, characterized in that the depression is U-shaped Course with legs straight toward the tear-open section and legs (29) parallel to the longitudinal center line (19) of the cover (1) and in the region of these legs has an approximately trapezoidal cross section (FIG. 4), and that the transverse beads (21, 22) have their ends each up to a distance (31) from et wa the bead width (34) to the score line sections (9) in the tear-open section (16). 2. Tear-off lid according to claim 1, characterized in that the two legs (24) of the bead-like depression end on a line (28) which extends transversely to the longitudinal center line (19) of the grip tab (5) as a tangent to the rivet shank (4a). 3. Tear-off cover according to claim 1, characterized in that the depressions (21, 22, 23, 24) of the bead assembly projecting towards the underside of the cover have substantially the same depth. 4. Tear-off cover according to one of claims I to 3, characterized in that the arcuate web section (23) starting from the one transverse bead (22) and the transverse beads (21, 22) also have a trapezoidal cross section. 5. tear-open lid according to one of claims 1 to 4, characterized in that the width and / or the depth of the two legs (24) of the U-shaped recess in the direction from the web portion (23) to the free end (26) of the legs (24 ) steadily decreases. 6. Tear-off cover according to one of claims 1 to 5, characterized in that the grip tab (5) on the tear-open area (6) is attached or bent so that at least part of its handle portion (12) at least partially in the depth of the bead area (21 , 22,23,24). 7. Tear-off cover according to one or more of claims 1 to 6, characterized in that it is made of a sheet metal with a thickness of less than 0.24 mm.

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