Furnace for manufacture of striationfree quartz tubing
Abstract
Abstract A furnace includes a refractory metal container for melted quartz surrounded by an electric heater. The bottom of the container has an orifice which includes a mandrel for the purpose of forming quartz tubing. In the cover of the furnace are a plurality of feed holes through which sand-filled quartz tubes can be introduced into the furnace. The furnace also has gas passages surrounding the holes, the purpose of which is to introduce and maintain a nonoxidizing gas atmosphere in the container and to form a gas lock around the quartz tubes to prevent air from entering the furnace. Included also are movable vacuum supports for supporting the quartz tubes and advancing them into the furnace.
Inventors
- 👤 F Loughridge
- 👤 W Finch
Bibliographic Details
Claims Analysis
Total Claims: 0References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-20 | 1976-08-21 | 1977-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-20 | 1980-08-21 | 1981-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-20 | 1984-08-21 | 1985-02-20 | $7700.00 | Window Closed / Lapsed |