1. Field of the Invention
The invention relates to the method of positionally fixing a tab on a sheet metal lid for attaching to a body of a beverage can.
2. Discussion of Background Information
When the tab is in an attached condition to the sheet metal lid, it is known by the expert as a SOT (Stay on Tab), which is provided for opening an openable area in the surface of a lid (usually designated as “panel”). For this purpose, the tab is taken at a grip end and raised with a vertical tilting motion for breaking open an openable area along a line of weakness (usually called score line) with its opening end.
Particularly when large opening ends (LOEs) are used for the openable area, difficulties are encountered in the related art when fixing the positions of the tab in an attached condition to the sheet metal lid. Suggestions on this topic have already been made, for example in U.S. Pat. No. 5,799,816 (Schubert). In this document, a breaking-through of an attaching portion of the tab is proposed, which attaching portion is usually designated as “rivet island”. The attaching portion is secured to the panel of the sheet metal lid through a shaped rivet and overlaps a round to elongated reformed bead with an opening provided in the attaching portion. The bead may also be formed after attaching the tab, compare column 3, lines 63–67, column 5, lines 37–44, claim 3 of the above-noted document and the associated graphical illustration in FIGS. 2 and 4 thereof.
The invention addresses the technical problem of achieving the same effect, but with an improved manufacture and reliability of the anti-rotation block and with an improved positional alignment of the tab in the attached condition. For this purpose, a method is proposed.
The present invention improves the positional alignment of a tab in an attached condition arranged on a panel, as well as improves the manufacture and reliability of the anti-rotation block.
According to one feature of the invention, an already present peripheral edge on a usual tab is used, the edge not having to be specifically embodied additionally for obtaining the rotation barrier after the attachment of the tab to the panel (“staking”). The only manipulation is effected on the sheet metal lid itself, which is provided with a shape, as is the rivet in a preliminary phase, which shape may also be pre-formed together with the formation of the rivet and subsequently modified in shape, or more precisely “reformed”, in a further processing step of the sheet metal lid being manufactured. The projection may thus be formed integrally with the sheet metal lid, as is the securing point by one-piece manufacturing for the attaching portion of the tab.
The projection does not protrude through an opening of the attaching portion, and the attaching portion is not provided with an opening beforehand, but the attaching portion remains entire and a blocking device that acts on the attaching portion from an outside is provided.
It is advantageous if at least one of the projections has an asymmetrical cross section, having a steeper flank facing the attaching portion than the flank facing away from the attaching portion. Such a shape may also be selected for punctiform or oval projections.
In a subsequent reshaping, reforming, or post-forming, the thickness of a top side of the (strip-shaped) projection is reduced. Thereby, solidification of the portion as well as of the projection as a whole is achieved. This also applies to the method. The score line may be introduced not simultaneously with the reforming, in temporally shifted or offset processing steps. The same is valid for the pre-forming of the bead, which is not shaped at the same time, as the score line is introduced.
In order to obtain the blocking effect, which may also be a limiting effect, which is to be understood such as to completely prevent a rotating movement up to substantially limit the rotating movement, an outer edge of the flat attaching portion (rivet island) abuts against the projection that is shaped to protrude out of the sheet metal lid.
The projection may have strip shape (line shape) and be aligned transversely and/or parallel to a longitudinal extension of the tab (longitudinal axis or longitudinal plane), engaging at a correspondingly aligned peripheral edge of the attaching portion for its blocking effect or being provided very closely adjacent thereto. In a longitudinal extension, the projection may extend over more than 30%, or possibly over more than 50% to more than 80% of the width of the attaching portion.
Several projections may be provided, not all projections having to be assigned to the same outer edge portion of the attaching portion. The projections may also be differently embodied, i.e. strip-shaped, round to oval, or a combination thereof. If a line-shaped outer edge portion of the attaching portion is provided, a line-shaped (strip-shaped) embodiment of the projections may be advantageous. The line-shaped strip design may also be achieved by arranging at least two punctiform projections in line, which then form a group that is assigned to the same outer edge portion of the attaching portion.
If several projections are provided according to the description given hereinbefore, they do not have to engage the same edge line of the attaching portion at the start of a rotating movement, but instead may be assigned to different outer edges. If a strip shape is provided for a projection, it may be designed to have a length longer than the diameter of the finished rivet head.
The attaching portion being formed from a piece of the central portion of the tab, only minor gaps are visible between the attaching portion, which is displaced downwards to a lower plane by a double buckling line, and the somewhat higher, parallel plane of the rest of the tab. Accordingly, the mounting of the projections on at least one of the free peripheral edges facing outward from the attaching portion is barely or only poorly visible from the outside, so that the rotation blocking is virtually invisible to the observer. A colored tab is not changed further in its colored shape.
Reference is made to the content of the disclosure of the co-pending US application (as mentioned in the introductory part). The present invention is further described in the detailed description which follows, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:
a shows the first stage of three stages in a manufacturing process of a sheet metal lid, which introduces, in part, a seamable edge, a U-shaped bead, a mounting place and projections.
a shows the second stage of three stages in a manufacturing process of a sheet metal lid, which introduces, in part, a score line or weakening line and a mounting place, and;
a shows the third stage of three stages in a manufacturing process of a sheet metal lid, which introduces, in part, an eyeball shaped bead, beads or projections and finger depression;
a is a cross section along line C—C in
a is a cross section of an embodiment of the invention corresponding to the illustration in
a to 3a show the sheet metal lid according to a method having a visible edge portion 12 as a seamable edge suitable for seaming to the body of a beverage can. The sheet metal lid itself is produced from thin sheet metal, typically less than 0.24 mm, and has already passed through preceding workstations before reaching the stage shown in
According to the
At one manufacturing station, the re-forming of the three beads 20 (or also 21a, 21b) is improved or designed more exactly. The “re-forming”, results in a formation of the beads (projections) as used later for the positional fixing, according to
a shows the cross section extending in a longitudinal direction, as determined by the longitudinal midplane 100 for
The re-forming step comprises a designing shaping of the pre-form 20* with a coining (an embossing operation) for further flattening the top surface 20c. In the re-forming process, the tool is applied likewise from the top and from the bottom for the re-forming. The slight bend according to
Additionally, in the final form, the attaching portion 31, which is mounted at the rivet 11, and the tab 30 are already attached according to
In this context, a modified sequence of the two-stage re-forming may be performed besides the processing sequence according to
If multiple projections are used for blocking rotating movements all pre-forms 20* are shaped according to
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Number | Date | Country | |
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20060010956 A1 | Jan 2006 | US |