US-12623951-B2 - Method of manufacturing an optical fiber and production system therefor

Abstract

A method of manufacturing optical fiber in an optical fiber production system is provided. The method includes providing a draw furnace operatively coupled to a slow cooling device along a draw pathway, drawing the optical fiber from an optical fiber preform in the draw furnace and along the draw pathway, heat treating the optical fiber in the slow cooling device positioned along the draw pathway, the slow cooling device comprising an inlet, an outlet, and a process tube extending between the inlet and the outlet, and selecting an opening size of an outlet nozzle operatively coupled to the outlet based on a draw speed of the optical fiber.

Inventors

• Maxim Evgenyevich Blyum
• Elena Alekseevna Chizhova-Notkina
• Nikolay Anatolyevich Panin

Assignees

• CORNING INCORPORATED

Dates

Publication Date

20260512

Application Date

20220830

Claims (18)

1. 1 . A method of manufacturing optical fiber in an optical fiber production system, the method comprising: providing a draw furnace operatively coupled to a slow cooling device along a draw pathway; drawing the optical fiber from an optical fiber preform in the draw furnace and along the draw pathway in a draw direction; heat treating the optical fiber in the slow cooling device positioned along the draw pathway, the slow cooling device comprising an inlet, an outlet, and a process tube extending between the inlet and the outlet, wherein the optical fiber induces a gas boundary layer extending outward from the optical fiber and moving in the draw direction; and adjusting an opening size of an outlet nozzle operatively coupled to the outlet with an actuator based on a draw speed of the optical fiber, wherein the opening size of the outlet nozzle is selected to have a first opening size at a first draw speed and a second opening size that is greater than the first opening size at a second draw speed that is greater than the first draw speed, and wherein the induced gas boundary layer is larger at the second draw speed compared to the first draw speed.
2. 2 . The method of claim 1 , wherein the actuator is controlled by a controller.
3. 3 . The method of claim 1 , wherein the step of adjusting the opening size of the outlet nozzle comprises selecting one of a plurality of outlet nozzle sizes based on the draw speed.
4. 4 . The method of claim 1 , wherein the process tube comprises a process tube wall and a plurality of heating zones, each heating zone comprising at least one heating element.
5. 5 . The method of claim 1 , further comprising the step of inducing gas flow from a gas distribution assembly fluidly coupled to the outlet of the slow cooling device into the process tube of the slow cooling device, such that gas flows within the process tube in an upward direction.
6. 6 . The method of claim 5 , wherein the optical fiber is drawn within the process tube in a draw direction that is opposite the upward direction and wherein the optical fiber translating within the process tube induces a gas boundary layer extending radially outward from the optical fiber in the draw direction.
7. 7 . The method of claim 6 , wherein the outlet nozzle is located in the gas distribution assembly.
8. 8 . The method of claim 1 , wherein the slow cooling device comprises an annealing furnace.
9. 9 . The method of claim 1 , further comprising the step of coating the optical fiber after the step of heat treating the optical fiber.
10. 10 . The method of claim 1 , further comprising the step of collecting the optical fiber with a fiber collection unit.
11. 11 . The method of claim 1 , further comprising the steps of: detecting a change in the draw speed of the optical fiber; and selecting a different opening size of the outlet nozzle based on the change in the draw speed of the optical fiber.
12. 12 . The method of claim 11 , further comprising the step of adjusting the opening size of the outlet nozzle to the selected different opening size.
13. 13 . An optical fiber production system comprising: a draw furnace configured to draw an optical fiber from an optical preform along a draw pathway extending from the draw furnace, in a draw direction; a slow cooling device positioned along the draw pathway, wherein the slow cooling device comprises: an inlet; an outlet; and a process tube extending between the inlet and the outlet; an adjustable outlet nozzle located proximate to the outlet, wherein the adjustable outlet nozzle has an outlet opening size configured to be adjusted based on draw speed of the optical fiber, wherein the outlet opening size of the adjustable outlet nozzle is selected to have a first opening size at a first draw speed and a second opening size that is greater than the first opening size at a second draw speed that is greater than the first draw speed; a fiber collection unit positioned along the draw pathway; and a gas distribution assembly positioned along the draw pathway and fluidly coupled to the 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 upward direction, wherein the slow cooling device is positioned between the draw furnace and the gas distribution assembly, wherein the optical fiber drawn through the process tube induces a gas boundary layer extending outward from the optical fiber and moving in the draw direction, and wherein the induced gas boundary layer is larger at the second draw speed compared to the first draw speed.
14. 14 . The optical fiber production system of claim 13 , further comprising: an actuator; and a controller for controlling the actuator to adjust the size of the opening of the adjustable outlet nozzle.
15. 15 . The optical fiber production system of claim 13 , wherein the outlet nozzle comprises one of a plurality of outlet nozzles each having an opening size selected based on the draw speed of the optical fiber.
16. 16 . The optical fiber production system of claim 13 , wherein the process tube comprises a process tube wall and a plurality of heating zones, each heating zone comprising at least one heating element.
17. 17 . The optical fiber production system of claim 13 , wherein the adjustable outlet nozzle is located within the gas distribution assembly.
18. 18 . The optical fiber production system of claim 13 , wherein the slow cooling device comprises an annealing furnace.

Description

This Application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 63/240,487 filed on Sep. 3, 2021, the content of which is relied upon and incorporated herein by reference in its entirety. BACKGROUND OF THE DISCLOSURE The present disclosure generally relates to an apparatus and methods for producing optical fibers, and more particularly relates to controlling the air flow through a slow cooling device, e.g., an annealing furnace, during an optical fiber production operation. Optical fibers are generally manufactured in an optical fiber production system and a method of manufacture in such a system typically includes drawing an optical fiber downward from a draw furnace along a path through multiple stages of production in an optical fiber draw tower. The optical fiber drawn from the draw furnace may be cooled in an annealing furnace which operates as a slow cooling device to cool the optical fiber within a controlled cooling range to minimize fictive temperature and Rayleigh scattering. When traversing the annealing furnace, gas flow patterns within the annealing furnace may alter properties of the optical fiber. It may be desirable to provide for an optical fiber manufacturing process and production system that achieves enhanced air flow at various fiber draw speeds. SUMMARY OF THE DISCLOSURE In accordance with one embodiment, a method of manufacturing optical fiber in an optical fiber production system is provided. The method includes the steps of providing a draw furnace operatively coupled to a slow cooling device along a draw pathway, drawing the optical fiber from an optical fiber preform in the draw furnace and along the draw pathway, heat treating the optical fiber in the slow cooling device positioned along the draw pathway, the slow cooling device comprising an inlet, an outlet, and a process tube extending between the inlet and the outlet, and selecting an opening size of an outlet nozzle operatively coupled to the outlet based on a draw speed of the optical fiber. In accordance with another embodiment, an optical fiber production system is provided. The optical fiber production system includes a draw furnace configured to draw an optical fiber from an optical preform along a draw pathway extending from the draw furnace, and a slow cooling device positioned along the draw pathway. The slow cooling device includes an inlet, an outlet, and a process tube extending between the inlet and the outlet. The optical fiber production system also includes an adjustable outlet nozzle located proximate to the outlet, wherein the adjustable outlet nozzle has an outlet opening size adjusted based on draw speed of the optical fiber, and a fiber collection unit positioned along with draw pathway. Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments, and together with the description serve to explain principles and operation of the various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of an optical fiber production system configured with an annealing furnace having a gas distribution assembly and an outlet nozzle, according to one embodiment; FIG. 2 is a schematic diagram of a process tube of the annealing furnace having an outlet nozzle at the bottom end thereof, according to another example; FIG. 3A is a top view of a first selectable outlet nozzle having a first size opening configured for use at a first fiber draw speed; FIG. 3B is a top view of a second selectable outlet nozzle having a different second size opening configured for use at a second fiber draw speed; FIG. 3C is a top view of a third selectable outlet nozzle having a different third size opening configured for use at a third fiber draw speed; FIG. 4 is a top view of an adjustable outlet nozzle for controlling the opening size for use at different fiber draw speeds, according to another embodiment; FIG. 5 is a graph illustrating the adjustable outlet nozzle effective size adjusted as a function of fiber draw speed, according to one example; FIG. 6 is a schematic diagram of the annealing furnace further illustrating plugging of the furnace outlet with the boundary layer of air; and FIG. 7 is a schematic diagram of the annealing furnace further illustrating the pressure and viscous