Coating apparatus – Immersion or work-confined pool type – Work extending through pool-confining wall area
Reexamination Certificate
1999-02-05
2001-09-04
Osele, Mark A. (Department: 1734)
Coating apparatus
Immersion or work-confined pool type
Work extending through pool-confining wall area
C118S420000, C118S429000, C118SDIG001
Reexamination Certificate
active
06284046
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical fiber resin coating apparatus, more particularly, an optical fiber resin coating apparatus for uniformly coating a resin on an optical fiber at a high speed.
2. Description of the Related Art
An optical fiber consisting of a core and a cladding provided at an outer circumferential of the core is produced by heating a preform of the optical fiber at a furnace and drawing it out from the furnace. Thereafter, the optical fiber is coated by a resin to produce a resin coated optical fiber.
Japanese Unexamined Patent Publication (Kokai) 6-279047 discloses a technology for coating a resin on an optical fiber.
FIG. 1
is a sectional view of an optical fiber resin coating apparatus of Japanese Unexamined Patent Publication (Kokai) 6-279047.
For coating resin on an optical fiber, in addition to the optical fiber resin coating apparatus shown in
FIG. 1
, as disclosed in Japanese Unexamined Patent Publication (Kokai) 6-279047, it is necessary to provide a resin supply means for supplying a resin to the optical fiber resin coating apparatus, a moving means for introducing an optical fiber into the optical fiber resin coating apparatus and drawing out a resin coated optical fiber from the optical fiber resin coating apparatus, a cooling means for cooling the drew out hot resin coated optical fiber, an outer diameter measurement means for measuring an outer diameter of the resin coated optical fiber, a control means for reading the measured outer diameter and controlling a drawing-out speed of the moving means, and resin supply parameters at the resin supply means, and a winding means for winding the cooled resin coated optical fiber. Below, the optical fiber resin coating apparatus in
FIG. 1
will be described in detail.
The optical fiber resin coating apparatus is formed as an assembly
3
of a combination of a nipple
1
and a resin coating die
2
.
A resin flow path
4
is defined at the gap (a boundary portion or an interface) of the nipple
1
and the resin coating die
2
. A nipple hole
5
of the nipple
1
and a die hole
6
of the resin coating die
2
are aligned in the assembly
3
at a same center line. The nipple hole
5
is constituted by a tapered-hole portion
5
a
and a land portion
5
b
. A resin supply chamber
7
is provided in the coating die
2
in a concentricity with the die hole
6
. A resin supply inlet
8
is also provided in the coating die
2
to supply a resin
9
to the resin supply chamber
7
. An optical fiber
10
is introduced into the nipple hole
5
and the die hole
6
to be coated with the resin
9
. The resin
9
is supplied to the die hole
6
at a predetermined pressure from the resin supply chamber
7
through the resin flow path
5
, to produce a resultant resin coated optical fiber
11
.
A meniscus-shaped portion
12
, which is a boundary plane of the resin
9
and the optical fiber
10
, is formed at an outlet portion of the nipple hole
5
, and a circular flow
13
of the resin
9
is caused in a cavity formed inside of tapered-hole portion
6
a of the die hole
6
in the resin coating die
2
.
The optical fiber resin coating apparatus disclosed in Japanese Unexamined Patent Publication (Kokai) 6-279047 suffers from the disadvantages of a partial lack (partial failure) of the coating of the resin on the optical fiber
10
in certain portions and/or unevenness of the diameter of the resin coated optical fiber
11
when the resin coated optical fiber
11
is drawn out from the optical fiber resin coating apparatus a high speed. Accordingly, the optical fiber resin coating apparatus of Japanese Unexamined Patent Publication (Kokai) 6-279047 suffers from the disadvantage of a limitation of the speed up of the drawing-out speed. Consequently, the optical fiber resin coating apparatus of Japanese Unexamined Patent Publication (Kokai) 6-279047 can not achieve a high productivity of the resin coating.
Japanese Examined Patent Publication (Kokoku) 7-91092 discloses a technology for preventing the partial lack (failure) of the coating and/or unevenness of the diameter of the resin coated optical fiber by suitably defining (designing) the size of the resin flow path
4
and the angle of the tapered-hole portion
6
a
in the resin coating die
2
.
The technology of Japanese Examined Patent Publication (Kokoku) 7-91092 can provide a good result below the drawing speed of the resin coated optical fiber is 1000 m/min, but still suffers from the disadvantages of the partial lack (failure) of the coating and/or unevenness of the diameter of the resin coated optical fiber at higher speed drawing.
According to an analysis of such disadvantages by inventors of the present invention, it was found that the reasons of the partial lack of the resin coating and/or the unevenness of the diameter of the resin coated optical fiber during high speed drawing had probably been due to disruptions in the circular flow
13
in the cavity of the tapered-hole portion
6
a
of the resin coating die
2
during high speed drawing. Namely, the high speed drawing of the resin coated optical fiber
11
disrupted the smooth circular flow in the cavity of tapered-hole portion
6
a
and caused vibration of the moving optical fiber
10
and destabilized the meniscus-shaped portion
12
formed at the outlet portion of the nipple hole
5
.
The countermeasures of the technology disclosed in Japanese Examined Patent Publication (Kokoku) 7-91092 run up against the disadvantages of the limit on speed of Japanese Unexamined Patent Publication (Kokai) 6-279047.
SUMMARY OF INVENTION
An object of the present invention is to provide an optical fiber resin coating apparatus enabling a uniform coating on an optical fiber during high speed drawing.
According to the present invention, there is provided an optical fiber resin coating apparatus comprising: a nipple including a nipple hole, a resin reserving chamber for reserving resin, and a resin supply inlet, said nipple hole having a first tapered-hole portion introducing an optical fiber therethrough and a first land portion continuing from the first tapered-hole portion and defining a first hole of a first diameter, a meniscus-shaped portion being positioned at an end of the first land portion; a resin coating die, and including a second tapered-hole and a second land portion continued to the second tapered-hole and defining a second hole of a second diameter which is defined a diameter of a resin coated optical fiber; and an intermediate die provided between the nipple and the resin coating die, including a third hole which communicates an end of the nipple hole and the second tapered-hole and has a third diameter, a fourth hole which communicates to the resin reserving chamber, a center axis of the nipple hole in the nipple, a center axis of the second hole of the resin coating die and a center axis of the third hole of the intermediate die being matched, a first resin flow path being defined at a boundary position of the nipple and the intermediate die, said first resin flow path communicating the resin reserving chamber, the end of the nipple hole and the third hole in the intermediate die, and a second resin flow path being defined at a boundary position of the intermediate die and the resin coating die, said second resin flow path communicating the third hole in the intermediate die, the second tapered-hole in the resin coating die and the fourth hole of the intermediate die.
Preferably, said first hole of the first diameter, said third hole of the third diameter, said second hole of the second diameter, said second tapered-hole, said first and second resin flow paths are defined, so that a first circular resin flow path, including said resin reserving chamber, said first resin flow path, said third hole, a cavity defined in said second tapered-hole, said second resin flow path, said fourth hole and said resin reserving chamber, in formed, and a second circular resin flow is formed in said cavity.
Preferably, said second tapered-hole in the resi
Koaizawa Hisashi
Orita Nobuaki
Arent Fox Kintner Plotkin & Kahn
Osele Mark A.
The Furukawa Electric Co. Ltd.
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