Title: Manufacture of a frangible element in sheet material

Abstract: A disclosure of making a frangible element or weakened line in metal sheet, especially tinplate, for use as a container end, an elongate frangible element of thinned metal is produced in the sheet, bounded on one side by a step in one surface and on the other side by a step in the other surface, the two steps as seen in section merging smoothly with concave curves into the respective surfaces of the frangible element. To take up excess metal from the thinning process, at least one hollow protuberance is formed in the sheet to one side of the frangible element. Press tool dies for performing the method are shown.

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Inventors: Cookson, William (Fareham, EN)

Application Number: 507669
Filing Date: 1974-09-20
Publication_date: 1976-04-20
Assignee: Cookson Sheet Metal Developments Limited (Southampton, EN)
Primary Class(es): 413/12
Other Classes:
US Patent Ref:

2071030	Feb, 1937	Fay	220/48.
2112231	Mar, 1938	Speidel	113/15.
3254790	Jun, 1966	Dunn	220/54.
3303958	Feb, 1967	Taylor	220/54.
3334777	Aug, 1967	Smyth	113/121.
3362569	Jan, 1968	Geiger	220/48.
3400852	Sep, 1968	Khoury	220/54.
3411470	Nov, 1968	Fraze	113/121.
3434623	Mar, 1969	Cookson	220/54.
3500939	Mar, 1970	Bozek	113/121.
3698590	Oct, 1972	Cookson	220/54.

Other Refs:
Primary Examiner: Lanham, C. W.
Assistant Examiner: Crosby, Gene P.
Attorney: Merriam, Marshall, Shapiro & Klose