Patent US1759636A successfully refreshed from Google Patents.
US3662789A
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US
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Mandrel for manufacturing filament coils and method for manufacturing filament coils
Assignee: Duro Test Corp
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Filing: 1970-08-24
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Granted: 1972-05-16
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Expires: 1990-08-24
Abstract
Abstract A mandrel and a method for manufacturing filament coils for electric lamps. The mandrel is coated with a material, such as copper, which does not alloy with the filament coil during annealing. The coil is wound on the coated mandrel and the mandrel is dissolved after the filament is annealed.
Inventors
- 👤 Ronald C Koo
- 👤 Joel Shurgan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:31
CPC Classifications
B; B21; B21F; B21F3/00; B21F3/02; B21F3/04; H; H01; H01K; H01K3/00; H01K3/02
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
14 words
The combination of claim 1 wherein the material of the inner core includes iron.
Claim 2
Dependent Claim
11 words
The combination of claim 1 wherein the coating material includes copper.
Claim 3
Dependent Claim
11 words
The combination of claim 2 wherein the coating material includes copper.
Claim 4
Dependent Claim
11 words
The combination of claim 4 wherein the filament material includes tungsten.
Claim 5
Dependent Claim
14 words
The combination of claim 2 wherein the coating material is copper alloyed with indium.
Claim 6
Dependent Claim
14 words
The combination of claim 2 wherein the coating material is copper alloyed with silver.
Claim 7
Dependent Claim
28 words
The combination of claim 1 wherein the material of the inner core is steel, the coating material is copper or a copper-alloy, and the filament material is tungsten.
Claim 8
Dependent Claim
58 words
The process of manufacturing lamp filaments comprising the steps of forming a mandrel having an inner core and an outer coating of a material different from that of the inner core, winding a coil of filament wire over the mandrel coating, annealing the filament wire by heating, and dissolving the mandrel from the filament in an acid bath.
Claim 9
Dependent Claim
35 words
The process of claim 9 wherein the annealing step is carried out at a temperature at which the mandrel coating material melts and a bond is formed between the filament wire and the coating material.
Claim 10
Dependent Claim
19 words
The process of claim 9 wherein said dissolving step is carried out in an acid bath containing nitric acid.
Claim 11
Dependent Claim
13 words
The process of claim 11 wherein said acid bath also contains sulfuric acid.
Claim 12
Dependent Claim
30 words
The process of claim 9 wherein the coating material includes copper and the annealing step is carried out at a temperature near the melting temperature of the copper coating material.
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) | 1975-05-16 | 1975-11-15 | 1976-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-16 | 1979-11-15 | 1980-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-16 | 1983-11-15 | 1984-05-16 | $7700.00 | Window Closed / Lapsed |