US5676724A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of improving the geometrical shape of a tube used for making a preform by selectively etching the bore of the tube
Assignee: Nexans France SAS
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Filing: 1995-10-17
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Granted: 1997-10-14
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Expires: 2015-10-17
Abstract
Abstract A method of improving the symmetry of a cylindrical silica tube to be used in making a preform having a circular outside surface eccentric to a circular inside surface thereby providing a varying tube thickness throughout the circumference of the tube which includes the following steps. The first step is locating a longitudinal generator line of the cylindrical tube at a greatest thickness of the tube at a given circumferential point on the tube, and while preventing the tube from rotating, etching in at least one pass the inside of the tube with a gas capable of decomposing silica, while heating the outside of the tube along that longitudinal generator line.
Inventors
- 👤 Gilles Barre
- 👤 Christian Le Sergent
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:13
CPC Classifications
C; C03; C03C; C03C15/00; C03B; C03B37/00; C03B37/01; C03B37/012; C03B37/01205; C03B37/01225; C03B37/01228
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
115 words
A method of reducing the eccentricity of a cylindrical silica tube to be used in making a preform having a circular outside surface eccentric to a circular inside surface, thereby forming a thickness which varies continuously throughout the circumference of the cylindrical tube, said method comprising the following steps: locating a longitudinal generator line of said tube facing out of a greatest circumferential thickness of said tube at a given point on the tube circumference; preventing the tube from rotating about its axis; and etching, in at least one pass, the inside of the tube with a gas, and decomposing silica, by heating an outside surface portion of the tube along said longitudinal generator line.
Claim 2
Independent Claim
115 words
A method of reducing the eccentricity of a cylindrical silica tube to be used in making a preform having a circular outside surface eccentric to a circular inside surface, thereby forming a thickness which varies continuously throughout the circumference of the cylindrical tube, said method comprising the following steps: locating a longitudinal generator line of said tube facing out of a greatest circumferential thickness of said tube at a given point on the tube circumference; preventing the tube from rotating about its axis; and etching, in at least one pass, the inside of the tube with a gas, and decomposing silica, by heating an outside surface portion of the tube along said longitudinal generator line.
Claim 3
Dependent Claim
42 words
A method according to claim 1, wherein the gas is one chosen from the group consisting of: SF 6 , CF 4 , CCl 2 F 2 , C 2 F 6 , C 3 F 8 , and SiF 4 .
Claim 4
Dependent Claim
37 words
A method according to claim 1, wherein said heating step comprises applying heat over an angular sector of about 60° about the circumference of said silica tube centered on said longitudinal generator line at said given point.
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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) | 2000-10-13 | 2001-04-14 | 2001-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-10-13 | 2005-04-14 | 2005-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-10-13 | 2009-04-14 | 2009-10-14 | $7700.00 | Window Closed / Lapsed |