JP3199657B2 - Equipment for manufacturing glass preforms for optical fibers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing a glass preform for an optical fiber, and more particularly, to a method for preventing undeposited fine particles adhering in a chamber from peeling and sooting, thereby achieving stable manufacturing. The present invention relates to a device that enables the following.

[0002]

2. Description of the Related Art Conventionally, glass preforms for optical fibers have been VA
The glass fine particles produced by the flame hydrolysis reaction of the glass raw material gas in the oxyhydrogen flame in the chamber by the D method or the like, and the glass fine particles not deposited on the base material are exhausted from the exhaust pipe to the outside of the chamber together with the generated HCl gas and the like. I have.

[0003]

However, due to the exhaust,
All undeposited glass particles are not discharged out of the chamber.The glass particles fill the chamber and the exhaust pipe, adhere in large quantities to the inner walls, etc., and adhered glass particles flow into the chamber, and the base material being deposited It re-adheres to the surface and causes foam of the base material. In addition, there is a problem in that the undeposited glass fine particles that have fallen into the chamber fly as soot, adhere to windows of the control system, and disturb the control system. Therefore, conventionally, this problem has been dealt with by increasing the displacement. However, in recent years, when a large base material is manufactured, the manufacturing time becomes longer and the base material becomes larger, so that the distance between the chamber inner wall and the base material becomes shorter, and the floating glass particles easily adhere to the inner wall and the like. In addition, the adhered glass particles are peeled off, causing bubbles and disturbance of the control system, thereby causing a problem that it is difficult to manufacture a stable base material.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an object to provide an apparatus for manufacturing a glass base material for an optical fiber, comprising a burner, an exhaust pipe, and a target in a chamber. In an apparatus for manufacturing an optical fiber preform by depositing glass fine particles synthesized in the above, a position in the chamber where glass fine particles easily adhere,
Alternatively, a groove is formed at a position where the fine particles are easily peeled off when the fine particles adhere. By forming a groove at a position where the deposited glass particles easily adhere to the conventional chamber, or at a position where the particles easily adhere when the particles adhere, the glass particles once adhered to the inner wall are peeled off and sooted into the chamber again. This is to prevent them from dancing.

[0005]

FIG. 1 (a) shows an example of an apparatus for manufacturing a glass preform for an optical fiber according to the present invention, wherein reference numeral 1 denotes a chamber, 2 denotes a burner for a core, and 3 denotes a burner for a clad. A burner, 4 is a target, 5 is an exhaust pipe, 6 is a porous glass base material, and 7 is a groove. FIG. 1 (b) shows A
FIG. 5 is an enlarged view of a case where a portion of the groove 7 is formed in a mesh shape on the inner wall. The glass preform for optical fiber is manufactured by rotating a target 4 in a chamber 1 and applying an oxyhydrogen flame of a core glass material gas and a cladding glass material gas from a core burner 2 and a cladding burner 3 respectively. The glass fine particles for the core and the glass fine particles for the clad generated by the hydrolysis reaction are deposited and raised in the axial direction to form the porous glass base material 6, and the hydrochloric acid gas and the undeposited glass fine particles are discharged from the exhaust pipe 5. At this time, as shown in FIG. 1 (b), a groove is formed in a portion of the chamber where soot is likely to adhere, so that the surface area of the chamber inner wall is increased, and the adhered glass particles are more firmly adhered to the inner wall. The glass base material is manufactured so that the attached fine particles are not peeled off. By this method, the glass base material is dropped into the chamber and adheres to the porous glass base material again. In addition, it is possible to prevent bubbles and the like of the base material from being caused, and to prevent the soot from adhering to the control window or the like as soot. The location of the groove in the chamber is a place where soot easily adheres or a place where the adhered substance is easily peeled off. Part or all of the inner wall of the chamber, part or all of the exhaust pipe, part or all of the device parts. Is good. The grooves may be arranged in a mesh or lattice shape, and the area thereof may be larger than the area of a place where soot is easily attached. In this manner, by forming grooves on the inner wall of the chamber, the pressure taps other than the exhaust pipe, and the outer wall and the inner wall of other device parts in the same manner, it is possible to further prevent the attached fine particles from flowing back into the chamber. .

[0006]

【Example】

EXAMPLE As shown in FIG. 1 (b), grooves having a width of 1 mm and a depth of 0.3 mm were formed at intervals of 1 mm on the inner wall of the upper part of the chamber in part A of FIG.
Using a chamber with an outer diameter of 250 mm attached vertically and horizontally by 100 mm × 200 mm, the target rod is suspended in the chamber.
While rotating up at rpm, SiCl ₄ with Ar carrier gas
100SCCM, GeCl ₄ is 20SCCM with Ar carrier gas, hydrogen gas
2.5SLM, oxygen gas 5SLM for core burner, SiCl ₄ for Ar
350SCCM for carrier gas, 30SLM for hydrogen gas, 30 for oxygen gas
SLM is supplied to each of the clad burners, and the generated glass particles are deposited, 50 porous base materials having an outer diameter of 100 mm and a length of 1000 mm are manufactured, and sintered at 1500 ° C to obtain a glass base material. Was. This glass base material had no problem such as peeling of any soot during production, and did not contain air bubbles.

Comparative Example Five porous glass preforms having an outer diameter of 100 mm and a length of 1000 mm were manufactured in the same manner as in the example except that no groove was formed in the chamber. In, the soot adhering to the inner wall of the chamber was peeled off, and one of the soot adhered to the window of the control system, and the control was disrupted and stopped.
In addition, it was confirmed that a large amount of bubbles was mixed in the glass base material produced by using these porous glass base materials as sintered glass.

[0008]

According to the present invention, by preventing the deposited particles deposited on the inner wall from being peeled off during manufacturing, soot in the chamber can be reduced and soot can be prevented from entering the base material or the like. A fiber preform without contamination can be stably manufactured.

[Brief description of the drawings]

FIG. 1A is an example of an apparatus for manufacturing a glass preform for an optical fiber. (b) It is an enlarged view of the groove of A part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Chamber 2 ... Burner for cores 3 ... Burner for claddings 4 ... Target 5 ... Exhaust pipe 6 ... Porous glass base material 7 ... Groove

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-320127 (JP, A) JP-A-56-32345 (JP, A) JP-A-62-171938 (JP, A) JP-A 60-320 346232 (JP, A) JP-A-60-41537 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C03B 37/018

Claims (4)

(57) [Claims] An apparatus for manufacturing an optical fiber preform by depositing a glass fine particle synthesized in a flame of a burner on a target, provided with a burner, an exhaust pipe, and a target in the chamber. position,
Alternatively, an apparatus for manufacturing a glass base material for an optical fiber, wherein a groove is formed at a position where the fine particles are easily peeled off when the fine particles adhere. 2. The apparatus for manufacturing a glass preform for an optical fiber according to claim 1, wherein a groove is formed in an inner wall of the chamber. 3. The apparatus for manufacturing a glass preform for an optical fiber according to claim 1, wherein grooves are formed on both the inside and outside of the exhaust pipe in the chamber. 4. The apparatus for manufacturing a glass preform for an optical fiber according to claim 1, wherein the groove is formed at a position where the glass particles of the equipment in the chamber are easily attached.