Hooded torch for synthesizing glass particulates

Details Hooded torch for synthesizing glass particulates Hooded torch for synthesizing glass particulates

2000-06-22

2002-01-01

Derrington, James (Department: 1731)

Glass manufacturing

Fiber making apparatus

Having coating or treating means

C065S414000, C065S421000, C239S422000, C239S423000, C239S424500

Reexamination Certificate

active

06334339

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hooded torch for synthesizing glass particulates used when producing a porous glass preform by a VAD process, an OVD process, or the like.
2. Description of the Related Art
FIG. 1
is a view of the configuration of torches of the related art used for producing (synthesizing) a porous glass preform
1
by the VAD process.
The apparatus illustrated in
FIG. 1
uses a hooded core glass particulate synthesizing torch
2
for forming a core portion
1
a
of the porous glass preform
1
and a hooded cladding glass particulate synthesizing torch
3
for forming a clad portion
1
b
of the porous glass preform
1
so as to deposit glass particulates synthesized by a flame hydrolysis reaction in the flames
4
and
5
of the torches
2
and
3
on the lower end of a rotating, rising porous glass preform
1
. The hooded glass particulate synthesizing torch
2
is comprised of a glass particulate synthesizing torch body
2
A and a hood
7
provided so as to project out at an outer circumference of the front end of the torch body
2
A. Also the hooded glass particulate synthesizing torch
3
is comprised of a glass particulate synthesizing torch body
6
and a hood
7
provided so as to project out at the outer circumference of the front end of the torch body
6
.
FIG. 2
is a view of the configuration of another torch of the related art for producing (synthesizing) a porous glass preform
9
on the outer circumference of a vitrified starting material
8
(frequently used for core) by the OVD process.
The apparatus illustrated in
FIG. 2
uses a torch for forming a porous glass preform
9
, that is, a hooded glass particulate synthesizing torch
3
having a structure similar to that mentioned before, to deposit glass particulates synthesized by a flame hydrolysis reaction in the flame
5
of the torch
3
on the outer circumference of the starting material
8
rotating around a center axial line. Further, it either makes the starting material
8
reciprocally move in a direction of its center axial line or makes the hooded glass particulate synthesizing torch
3
reciprocally move in a longitudinal direction of the starting material
8
.
Both of the porous glass preforms
1
and
9
formed by the apparatuses illustrated in FIG.
1
and FIG.
2
are then heat treated for dehydration, then vitrified to make transparent optical fiber preforms.
The transparent porous glass preform is then heated and drawn to make for example a single mode optical fiber comprised of a core with a diameter of 10 &mgr;m and a cladding with a diameter of 125 &mgr;m formed on the outer circumference of the core.
In the hooded glass particulate synthesizing torch
3
of the related art used in the VAD process and the OVD process, however, the projection length D of the hood
7
from the front end of the torch body
6
was determined by the outer diameter of the torch body
6
or the flow rate of the feedstock gas, but there were problems in cost and yield such as the deposition effect being insufficient or glass particulates
10
depositing on the inner wall of the hood
7
as shown in FIG.
1
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a hooded glass particulate synthesizing torch capable of improving the deposition effect and capable of improving the yield.
According to the present invention, there is provided a hooded glass particulate synthesizing torch provided with at least a glass particulate synthesizing torch body having a feedstock gas injection passage formed at the center of its front end, a combustible gas injection passage formed concentrically at the outer circumference of the feedstock gas injection passage, and a plurality of small diameter combustion aid gas injection passages formed in the combustible gas injection passage along the outer circumference of the feedstock gas injection passage and a hood projecting out at the outer circumference of the front end of the torch body.
In the hooded glass particulate synthesizing torch according to the present invention, use is made of a hood having a length satisfying the condition of the following relation:
0.5≦
D/L
≦2.0
where L is the focal distance, that is, a distance from a point P, to which the small diameter combustion aid gas injection passages are directed and on an extension of the center line of the torch body in front of the torch body, to the front end of the torch body, and D is the hood length, that is, the distance from the front end of the hood to the front end of the torch body.


REFERENCES:
patent: 4389235 (1983-06-01), Jung
patent: 4765815 (1988-08-01), Danzuka et al.
patent: 5735928 (1998-04-01), Sayce et al.
patent: 5922100 (1999-07-01), Cain et al.
patent: 5979185 (1999-11-01), Blackwell et al.
patent: 0 237183 (1987-07-01), None
patent: 2 124205 (1984-02-01), None
patent: 62-162637 (1987-07-01), None
patent: 2000-191337 (2000-07-01), None
Abstract of JP 62-162637, Jul. 1987.*
Abstract of JP 2000-191337, Jul. 2000.

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