System and methods for processing an optical fiber preform

Patent metadata

Field	Value
Publication number	US-2020283329-A1
Application number	US-202016799185-A
Country	US
Kind code	A1
Filing date	Feb 24, 2020
Priority date	Mar 5, 2019
Publication date	Sep 10, 2020
Grant date	—

Abstract

A system and methods are described herein for preheating a preform in a preheater furnace and then transferring the preheated preform to a consolidation furnace for chemical treatment and sintering the preform into a clear glass which can be drawn into optical fiber. In addition, the preheater furnace is described herein which is configured to heat the preform per a predetermined heat-profile until the preform is uniformly heated to a temperature above 1000° C.

First claim

1 . A system comprising:
a preheater furnace configured to receive a porous preform and to heat the porous preform to form a preheated preform, the preheated preform having an outer surface; and a transfer stage configured to transfer the preheated preform from the preheater furnace to a consolidation furnace configured to sinter the preheated preform to form a consolidated preform, the transfer including removing the preheated preform with the outer surface at a first temperature from the preheater furnace and inserting the preheated preform with the outer surface at a second temperature into the consolidation furnace, the first temperature exceeding 1000° C. and the second temperature being greater than room temperature and less than the first temperature.

2 . The system of claim 1 , wherein the preheater furnace is further configured to rotate the porous preform.

3 . The system of claim 1 , wherein the porous preform has a bulk density in the range from 0.35 g/cm 3 -0.70 g/cm 3 .

4 . The system of claim 1 , wherein the preheated preform has a surface density in the range from 0.35 g/cm 3 -0.70 g/cm 3 .

5 . The system of claim 1 , wherein the first temperature is less than 1200° C.

6 . The system of claim 1 , wherein the second temperature is greater than 600° C.

7 . The system of claim 1 , wherein the second temperature is less than the first temperature by less than 400° C.

8 . The system of claim 1 , wherein the preheated preform has a uniform temperature greater than 1000° C.

9 . The system of claim 1 , wherein the preheater furnace comprises a maximum operating temperature of 1200° C.

10 . The system of claim 1 , wherein the consolidated preform has a bulk density greater than 1.90 g/cm 3 .

11 . The system of claim 1 , wherein the preheater furnace comprises:
a body having an automated door attached thereto which when opened provides access to an interior space of the body and when closed prevents access to the interior space of the body; one or more heating elements and associated insulation located within the body, wherein the one or more heating elements are configured to radiate heat to heat the preform while the preform is located within the interior space of the body; a box muffle configured to prevent the one or more heating elements and the insulation from contaminating an outer surface of the preform while the preform is located within the interior space of the body; a rotation-translation mechanism configured to rotate the preform while the preform is located within the interior space of the body; and, wherein the rotation-translation mechanism is further configured to be retracted to move the preform into the interior space of the body and further configured to be extended to move the preform out from the interior space of the body.

12 . A method of processing an optical fiber preform, comprising:
loading a porous preform into a preheater furnace; heating the porous preform in the preheater furnace to form a preheated preform, the preheated preform having an outer surface at a first temperature, the first temperature exceeding 1000° C.; transferring the preheated preform from the preheater furnace to a consolidation furnace, the outer surface of the preheated preform cooling to a second temperature during the transferring, the transferring including inserting the preheated preform with the outer surface at the second temperature into the consolidation furnace, the second temperature being greater than room temperature and less than the first temperature.

13 . The method of claim 12 , wherein the porous preform has a bulk density in the range from 0.35 g/cm 3 -0.70 g/cm 3 .

14 . The method of claim 12 , wherein the preheated preform has a surface density in the range from 0.35 g/cm 3 -0.70 g/cm 3 .

15 . The method of claim 12 , wherein the first temperature is less than 1200° C.

16 . The method of claim 12 , wherein the second temperature is greater than 600° C.

17 . The method of claim 12 , wherein the second temperature is less than the first temperature by less than 600° C.

18 . The method of claim 12 , wherein the preheated preform has a uniform temperature greater than 1000° C.

19 . The method of claim 12 , further comprising rotating the porous preform in the preheater furnace.

20 . The method of claim 12 , further comprising sintering the preheated preform in the consolidation furnace.

21 . The method of claim 20 , further comprising doping or drying the preheated preform in the consolidation furnace.

22 . The method of claim 12 , further comprising forming a consolidated preform from the preheated preform in the consolidation furnace, the consolidated preform having a bulk density greater than 1.90 g/cm 3 .

23 . The method of claim 12 , wherein the transferring occurs in less than 10 min.

Assignees

• Corning Inc

Inventors

• Groh Raymond David
• Morse Joseph Leroy
• Shepard Bradley Kent
• Smith Ian Anthony
• Thornton Eric Wade

Classifications

• F27B5/13

  Arrangement of devices for discharging · CPC title

• F27B5/00

  Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated (furnaces through which the charge is moved mechanically or in which the charge moves by gravity F27B9/00) · CPC title

• C03B37/01853 Primary

  Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering · CPC title

• C03B37/0124

  Means for reducing the diameter of rods or tubes by drawing, e.g. for preform draw-down · CPC title

• C03B37/01884

  Means for supporting, rotating and translating tubes or rods being formed, e.g. lathes · CPC title