Patent US3602980A successfully refreshed from Google Patents.
US3602980A
Expired / Lapsed
US
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Method for forming a sheet metal joint
Assignee: Alcoa Corp
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Filing: 1968-12-23
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Granted: 1971-09-07
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Expires: 1988-12-23
Abstract
Abstract This disclosure describes a method for forming a sheet metal joint for attachment of a pull tab to a tear strip in a container end closure in which a bubble is first formed in the closure end panel, the bubble is reformed into a hollow rivet having a substantially cylindrical sidewall and an arcuate transverse end wall, and the rivet is staked or upset to compressively fold the transverse end wall thereof to form a head on the rivet which is at least as thick as the transverse end wall of the unstaked rivet.
Inventors
- 👤 Robert E Heffner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:55
CPC Classifications
B; B21; B21D; B21D51/00; B21D51/16; B21D51/38; B21D51/383; F; F16; F16B; F16B5/00; F16B5/04; F16B5/045; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49826; Y10T29/49908; Y10T29/49915; Y10T29/49938
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
269 words
A method for affixing a tab having an aperture therethrough to a container end closure of deformable sheet material comprising the steps of: a. forming a raised bubble in the end closure; b. reforming the bubble into an upstanding hollow rivet by supporting the bubble against a male die having a cylindrical punch with an arcuately domed working end projecting into said bubble, and advancing a female die against the male die to form a rivet with an upwardly arcuate central portion in its transverse end wall over the punch; c. positioning the tab over the end closure with said upstanding rivet extending through the aperture in the tab; and d. heading the rivet by moving a punch with a substantially flat working end against the arcuate central portion of the transverse end wall of the rivet while supporting the end closure against a die having an anvil extending into the hollow rivet to approximately the height of the upper surface of the tab, to progressively invert the arcuate transverse end wall and form an upwardly concave configuration therein with a depressed central portion and an annular portion contiguous therewith, and when said depressed central portion contacts and bears against the anvil, to fold the annular portion downwardly and outwardly to form a head on the rivet, the punch stopping before its working surface reaches a position with respect to the upper surface of the anvil equal to the thickness of the head of the rivet away from the upper surface of the anvil to avoid thinning the metal in the transverse end wall of the rivet during heading.
Claim 2
Independent Claim
269 words
A method for affixing a tab having an aperture therethrough to a container end closure of deformable sheet material comprising the steps of: a. forming a raised bubble in the end closure; b. reforming the bubble into an upstanding hollow rivet by supporting the bubble against a male die having a cylindrical punch with an arcuately domed working end projecting into said bubble, and advancing a female die against the male die to form a rivet with an upwardly arcuate central portion in its transverse end wall over the punch; c. positioning the tab over the end closure with said upstanding rivet extending through the aperture in the tab; and d. heading the rivet by moving a punch with a substantially flat working end against the arcuate central portion of the transverse end wall of the rivet while supporting the end closure against a die having an anvil extending into the hollow rivet to approximately the height of the upper surface of the tab, to progressively invert the arcuate transverse end wall and form an upwardly concave configuration therein with a depressed central portion and an annular portion contiguous therewith, and when said depressed central portion contacts and bears against the anvil, to fold the annular portion downwardly and outwardly to form a head on the rivet, the punch stopping before its working surface reaches a position with respect to the upper surface of the anvil equal to the thickness of the head of the rivet away from the upper surface of the anvil to avoid thinning the metal in the transverse end wall of the rivet during heading.
Claim 3
Dependent Claim
57 words
A method as set forth in claim 1 in which the closure is made of aluminum alloy sheet, and in said reforming of the bubble into a hollow rivet, the ratio of the radius of curvature of the domed end of the punch to the diameter of the punch is in the range of 0.48 to 0.66.
Claim 4
Dependent Claim
21 words
A method as set forth in claim 1 in which the transverse end wall of the rivet is thickened during heading.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-06 | 1975-03-08 | 1975-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-06 | 1979-03-08 | 1979-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-06 | 1983-03-08 | 1983-09-07 | $7700.00 | Window Closed / Lapsed |