Methods and systems for controlling air flow through an annealing furnace during optical fiber production

Patent metadata

Field	Value
Publication number	US-11237323-B2
Application number	US-201815899558-A
Country	US
Kind code	B2
Filing date	Feb 20, 2018
Priority date	Feb 28, 2017
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

An optical fiber production system includes an annealing furnace having a furnace inlet, a furnace outlet, and a process tube extending between the furnace inlet and the furnace outlet, the process tube having a process tube wall and a heating zone including at least one heating element. The optical fiber production system also includes a gas distribution assembly fluidly coupled to the furnace outlet and structurally configured to induce gas flow from the gas distribution assembly into the process tube such that gas flows within the process tube in an upflow direction.

First claim

What is claimed is:

1. An optical fiber production system comprising:
an annealing furnace comprising:
a furnace inlet;
a furnace outlet; and

a process tube extending between the furnace inlet and the furnace outlet, the process tube comprising a process tube wall and a heating zone comprising at least one heating element; and
a gas distribution assembly fluidly coupled to the furnace outlet and structurally configured to induce a gas flow from the gas distribution assembly into the process tube such that the gas flow within the process tube is in an upflow direction.

2. The optical fiber production system of claim 1 , wherein:
the gas distribution assembly comprises a gas distribution manifold and a retractable flow restrictor; and
the gas distribution manifold is positioned between the retractable flow restrictor and the furnace outlet.

3. The optical fiber production system of claim 2 , wherein:
the gas distribution manifold comprises a gas manifold inlet, a gas manifold outlet, and a gas manifold chamber positioned between and fluidly coupled to the gas manifold inlet and the gas manifold outlet; and
the gas manifold outlet is fluidly coupled to the furnace outlet.

4. The optical fiber production system of claim 3 , wherein:
the gas distribution manifold further comprises a manifold fiber passage positioned such that a draw pathway extending through the annealing furnace extends though the manifold fiber passage; and
the gas manifold outlet is positioned between the manifold fiber passage and the furnace outlet of the annealing furnace.

5. The optical fiber production system of claim 3 , wherein the gas distribution manifold further comprises a manifold restrictor plate positioned between and fluidly coupled to the gas manifold inlet and the gas manifold outlet, the manifold restrictor plate including a plurality of flow passages extending therethrough.

6. The optical fiber production system of claim 3 , wherein the gas distribution manifold further comprises one or more mass flow controllers fluidly coupled to the gas manifold inlet.

7. The optical fiber production system of claim 2 , wherein:
the retractable flow restrictor comprises a first retractable restrictor plate and a second retractable restrictor plate, each translatable between a restricted position and a relaxed position;
the first retractable restrictor plate and the second retractable restrictor plate define an opening therebetween; and
a diameter of the opening is larger when the first and second retractable restrictor plates are in the restricted position than when the first and second retractable restrictor plates are in the relaxed position.

8. The optical fiber production system of claim 1 , wherein the gas flow in the upflow direction is laminar.

9. The optical fiber production system of claim 1 , wherein the annealing furnace further comprises a furnace inlet channel fluidly coupled to the furnace inlet and a furnace outlet channel fluidly coupled to the furnace outlet.

10. The optical fiber production system of claim 9 , further comprising an optical fiber situated on a draw pathway extending from the furnace inlet channel to the furnace outlet channel within the process tube, the optical fiber comprising a gas boundary layer, the gas boundary layer comprising a diameter substantially equivalent to a diameter of the furnace inlet channel.

11. The optical fiber production system of claim 1 , wherein the gas distribution assembly is structurally configured to induce a flow of the gas flow through the furnace outlet into the process tube in the upflow direction to the furnace inlet.

12. The optical fiber production system of claim 1 , wherein the tube wall closes the process tube between the furnace inlet and furnace outlet.

13. A method of inducing gas flow in an annealing furnace, the method comprising:
translating an optical fiber within an annealing furnace along a draw pathway, the annealing furnace comprising:
a furnace inlet;
a furnace outlet; and
a process tube extending between the furnace inlet and the furnace outlet, the process tube comprising a process tube wall and a plurality of heating zones, each heating zone comprising at least one heating element; and

inducing a gas flow from a gas distribution assembly fluidly coupled to the furnace outlet into the process tube, the gas flow flowing within the process tube in an upflow direction.

14. The method of claim 13 , wherein the gas flow in the upflow direction is laminar.

15. The method of claim 14 , wherein the translating induces a gas boundary layer extending radially outward from the optical fiber, the gas boundary layer comprising laminar gas flow in the draw direction.

16. The method of claim 13 , wherein the optical fiber is translating along the draw pathway in a draw direction that is opposite the upflow direction.

17. The method of claim 16 , wherein the translating induces a gas boundary layer extending radially outward from the optical fiber, the gas boundary layer comprising laminar gas flow in the draw direction.

18. The method of claim 13 , wherein the gas flow comprises argon.

19. The method of claim 13 , wherein:
the gas distribution assembly comprises a gas distribution manifold and a retractable flow restrictor;
the gas distribution manifold is positioned between the retractable flow restrictor and the furnace outlet;
the gas distribution manifold comprises a gas manifold inlet, a gas manifold outlet fluidly coupled to the furnace outlet, and a gas manifold chamber positioned between and fluidly coupled to the gas manifold inlet and the gas manifold outlet; and the retractable flow restrictor comprises a first retractable restrictor plate and a second retractable restrictor plate, each translatable between a restricted position and a relaxed position.

20. The method of claim 19 , further comprising translating the optical fiber through the gas distribution manifold and the retractable flow restrictor along the draw pathway.

21. An optical fiber production system comprising:
a draw furnace configured to draw an optical fiber from an optical fiber perform along a draw pathway extending from the draw furnace;
an annealing furnace positioned along the draw pathway, wherein the annealing furnace comprises
a furnace inlet;
a furnace outlet; and
a process tube extending between the furnace inlet and the furnace outlet, the process tube comprising a process tube wall and a plurality of heating zones, each heating zone comprising at least one heating element;

a gas distribution assembly positioned along the draw pathway and fluidly coupled to the furnace outlet and structurally configured to induce a gas flow from the gas distribution assembly into the process tube such that the gas flow within the process tube is in an upflow direction, wherein the annealing furnace is positioned between the draw furnace and the gas distribution assembly; and
a fiber collection unit positioned along the draw pathway, wherein the gas distribution assembly is positioned between the annealing furnace and the fiber collection unit.

22. The optical fiber production system of claim 21 , wherein:
the gas distribution assembly comprises a gas distribution manifold and a retractable flow restrictor;
the gas distribution manifold is positioned between the retractable flow restrictor and the furnace outlet;
the gas distribution manifold comprises a gas manifold inlet, a gas manifold outlet fluidly coupled to the

Assignees

• Corning Inc

Inventors

• Billings Kenneth Duane
• Kingsbury Spencer Thomas
• Moore Robert Clark
• Todt Michael James
• Watson Johnnie Edward

Classifications

• C03B37/029 Primary

  Furnaces therefor · CPC title

• C03B2205/56

  Annealing or re-heating the drawn fibre prior to coating · CPC title

• G02B6/028 Primary

  with core or cladding having graded refractive index {(G02B6/02033, G02B6/02295 take precedence)} · CPC title

• C03B37/02727

  Annealing or re-heating · CPC title

• C03B37/027

  Fibres composed of different sorts of glass, {e.g. glass optical fibres}(C03B37/0253, C03B37/028 take precedence) · CPC title