Swiss Aluminium Ltd.

Siegfried Bloeck

Rudolf Luthi

Oldrich Stanek

Erich Hofling

Werner Diemi

A process for manufacturing a lid having at least one outlet opening wherein a closure strip is sealed onto the lid covering the outlet opening comprising heating the closure strip to a temperature range of approximately 115.degree.-170.degree. C. within 10-15 seconds prior to sealing the closure strip onto the lid.

Process of heat sealing a closure strip to a can lid

Can lids made of metal, lacquered on both sides and featuring a pouring outlet covered over with a closure strip having a sealing surface of polyamide, often exhibit inadequate bond strength between the closure strip and the lacquered can lid surface. The bond strength can be increased if the can lid, after the closure strip has been sealed onto it, is heated until the polyamide melts and then the can lid with closure strip is subsequently cooled.

Process for manufacturing a can lid

Lids made of aluminum alloys or ferrous material such as tin plate or tin free steel having at least one stamped out pouring hole and, if desired, at least one hole for air have hot sealed pull-off strips covering the said holes. On the inner side of the lids the region around the holes is pre-treated with an adhesive primer and then coated with a plastisol layer thus providing the cut edges at the holes with protection against attack by the contents of the can.

Process for manufacturing lids with a closure strip covering at least

The process of the present invention allows for the manufacture of lacquered aluminum or tin-plate rings which have the inner edge thereof bent over outwards so that they are suitable for the closures on cans for foodstuffs. A ring blank made of lacquered sheet is pre-shaped by deep drawing to form the curvature needed for bending over the inner cut edge. The final shaping of the pre-shaped blank into a ring for a can lid takes place, after stamping out the opening, by stretching and bending over the cut edge. When a tear-back membrane is sealed on to the bent-over edge, the ring is suitable as an easily opened closure for cans for foodstuffs.

Process for the manufacture of rings for lids for cans

The pre-fabricated pouring outlet in a lid for cans containing carbonated drinks lies basically at an angle of 0.degree. or 90.degree. to the rolling direction of the sheet from which the lid is made. The surface of the lid features at least one ring-shaped stiffening groove which points towards the can interior, is concentric with the periphery of the lid and is interrupted in the region of the pouring outlet. The diameter of the groove is 65-80% of that of the nominal diameter of the can. The stiffening groove raises the resistance of the lid towards pressure from inside the can by about 10%. This means that, when manufacturing a lid which has to withstand a specific pressure from inside the can, and using the same material, the thickness of the lid can be reduced to save material.

Grooved beverage can lid

The process of the present invention allows the manufacture of lacquered aluminum or tin-plate rings which have the inner edge thereof bent over outwards so that they are suitable for the closures on cans for foodstuffs. A ring blank made of lacquered sheet is pre-shaped by deep drawing to form the curvature needed for bending over the inner cut edge. The final shaping of the pre-shaped blank into a ring for a can lid takes place, after stamping out the opening, by stretching and bending over the cut edge. When a tear-back membrane is sealed on to the bent-over edge, the ring is suitable as an easyly opened closure for cans for foodstuffs.

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Kreuzlingen, Switzerland

Siegfried Bloeck