Receptacles – Closures – With closure opening arrangements for means
Patent
1997-08-12
1999-07-27
Cronin, Stephen K.
Receptacles
Closures
With closure opening arrangements for means
220268, 220269, 220906, 413 15, 413 17, B65D 1732, B21D 5138
Patent
active
059275367
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a metal easy open can lid which can be used for beverage cans and other general food cans and a wide range of other applications and to a process for the production thereof, more specifically it relates to an easy open can lid, composed of a surface treated metal sheet consisting of a metal sheet such as a sheet steel, an aluminum sheet, or metal sheet which has been plated with tin or given surface treatment coating such as a chromate coating, paint, and resin laminate, provided with an opening guide capable of easy opening of part of the lid manually.
BACKGROUND ART
In the past, easy open can lids enabling manual opening of part of the container lid have been made by placing the lid body on a flat lower mold half and pressing a sharp blade having the required contour shape from the top surface so that the cutting edge bites into the lid body whereby the V-shaped cross-section tear-along groove shown in FIG. 6 is formed and the shape of the opening piece is obtained. With this method, however, since the cutting edge was sharp, the coating film provided in advance for prevention of corrosion would be broken, necessitating repair coating later in the case of a steel lid and thereby resulting in higher manufacturing costs.
One method which has been recently used to prevent corrosion in place of the conventional lacquer coating has been to use a thermoplastic resin film at some locations. A thermoplastic resin film has a relatively superior drawability, and therefore, possibly would enable processing of an opening piece without breaking it depending on the processing method used. When forming a V-shaped cross-section tear-along groove by the above sharp blade, however, it is not possible to completely avoid breakage of the resin film.
The easy open lid (or easy open end) used for beverage cans, general food cans, and the like may be roughly classified into two types: ones provided with a tab using the lever principle and ones without a tab which allow people to directly push and open the lid by finger pressure. The ones provided with tabs further may be broken down into ones where the opening piece comprising part or all of the container lid is torn off by the tab to separate from the can body, i.e., the tear off types, and ones where it is left attached to the can body, i.e., the stay-on tab types. Both types use a coated aluminum sheet or sheet steel as a material, punch them out into the basic lid shape, place them on a flat bottom mold half, press an upper mold half having a sharp edge cross-section scoring blade projecting from it in the shape of the contour of the opening, and form an opening groove of the shape of the opening in the material. To facilitate the opening of the can, it is necessary to press the scoring blade to a depth of the opening guide groove of 1/2 to 2/3 of the thickness of the sheet before processing. If the depth of the opening guide groove is too shallow, the openability will be poor, while if too deep, the strength will be insufficient and the can will open upon even a small impact from the outside.
When the materials of easy open can lids are made extremely thin due to demands for easy opening etc., a considerable precision has been sought in the scoring tools as well, resulting in an extremely short life of the tools. Due to this problem, as described in Japanese Unexamined Patent Publication (Kokai) No. 55-70434 and Japanese Unexamined Patent Publication (Kokai) No. 57-175034, measures have been devised for prolonging the tool life by forming a thin upward-facing connecting piece between the opening piece and its surroundings and then pressing down the opening piece to make the connecting piece bend in the middle and form the opening guide groove and thereby form a tear-off type opening piece for the can.
Further, due to the fact that, with the conventional processing of an opening guide groove, defects occur in an organic film layer and the metal surface becomes exposed, repair coating has been applied to ensure resistance
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Supplementary European Search Report EP 96 90 3214 mailed Oct. 13, 1998.
Itoh Hiroshi
Izaki Teruaki
Manabe Kouji
Nishida Hiroshi
Oyagi Yashichi
Cronin Stephen K.
Newhouse Nathan
Nippon Steel Corporation
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