Patent US2272892A successfully refreshed from Google Patents.
Patent US3649224A successfully refreshed from Google Patents.
US3649224A
Expired / Lapsed
US
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Method of making nonsag filaments for electric lamps
Assignee: GTE Sylvania Inc
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Filing: 1968-04-18
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Granted: 1972-03-14
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Expires: 1988-04-18
Abstract
Abstract A tungsten wire, previously drawn to a predetermined diameter, is stretched at a stress between its elastic limit and about 95 percent of its ultimate tensile strength, thereby imparting a permanent elongation to the wire. The stressed wire is then coiled into filaments which, on recrystallization, have improved nonsag properties.
Inventors
- 👤 Warren A Anderson
- 👤 Wilfrid G Matheson
- 👤 Lester W Strock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:52
CPC Classifications
H; H01; H01K; H01K3/00; H01K3/02; Y; Y10; Y10S; Y10S75/00; Y10S75/95; Y10T; Y10T428/00; Y10T428/12; Y10T428/12014; Y10T428/12333; Y10T428/12431
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
31 words
The process according to claim 1 wherein the force used in stretching said wire is in the range between its elastic limit and about 95 percent of its ultimate tensile strength.
Claim 2
Dependent Claim
19 words
The process according to claim 1 including the step of stretching said wire between two pulleys having unequal circumferences.
Claim 3
Dependent Claim
21 words
The process according to claim 2 including the steps of forming coiled filaments from said stretched wire and recrystallizing said filaments.
Claim 4
Dependent Claim
23 words
The process according to claim 4 wherein said filaments are made from said wire having a diameter of about 1 to 50 mils.
Claim 5
Dependent Claim
18 words
The process according to claim 4 wherein the dopants for said tungsten powder include potassium, silica and aluminum.
Claim 6
Dependent Claim
10 words
Tungsten filaments manufactured according to the process of claim 4.
References Cited (Backward Citations)
US3278281A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-03-14 | 1975-09-13 | 1976-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-14 | 1979-09-13 | 1980-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-14 | 1983-09-13 | 1984-03-14 | $7700.00 | Window Closed / Lapsed |