JPH09241042A - Optical fiber coating device and manufacture of optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the device which restricts the variation in outer diameter of the coating layer of an optical fiber and reduces the variation in uniformity of its section by restrictiuy the rotation of the coating resin along the circumferential direction of the optical fiber from occurring. SOLUTION: In the device for coating an optical fiber 1 to form a single coating layer on the fiber 1 by using a combination of a nipple 2 and a coating die 3, the upper end face of the coating die 3 is formed into a flat face provided with plural rotation restricting walls 3b each placed in the radial direction. At the time of a allowing the optical fiber 1 to go out from a nipple hole 2a of the nipple 2 and to enter in to a die hole 3a of the coating die 3, the optical fiber 1 is brought into contact with a coating resin 8 which is supplied from the circumferential direction that orthogonally intersects the die hole 3a, by applying a pressure. Then, at the time of allowing the optical fiber 1 to pass through the die hole 3a tapered so that its diameter is gradually reduced in the direction toward the outlet, the optical fiber 1 is coated with the coating resin 8 while squeezing the resin 8 and drawn out to coat the optical 1 with a single coating layer and to manufacture the objective coated optical fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber coating apparatus for coating an optical fiber with a resin and an optical fiber manufacturing method.

[0002]

2. Description of the Related Art Conventionally, in the production of an optical fiber, an optical fiber is drawn by pulling while heating a preform, a surface of the optical fiber is coated with a resin or the like, and this is cured by a curing device. It is wound up on a winder after passing through. A device for coating an optical fiber is known, for example, from Japanese Utility Model Publication No. 2-38437, Japanese Utility Model Publication No. 2-38438, and Japanese Patent Publication No. 5-4347.

FIG. 4 is a sectional view of a conventional optical fiber coating apparatus. In the figure, 1 is an optical fiber, 21 is a nipple,
21a is a nipple hole, 21b is a first coating resin introducing hole,
22 is the first coating die, 22a is the die hole, and 22b is the second
Fluid introduction hole, 23 is a second coating die, 23a is a die hole, 24 is a first reservoir chamber, 25 is a first throttle portion, 26 is a first orthogonal flow path, and 27 is a second reservoir chamber. , 28 is a second throttle portion, 29 is a second orthogonal flow path, 30 is a first coating resin,
Reference numeral 31 is a second coating resin. This prior art is known from the above-mentioned Japanese Utility Model Publication No. 2-38437,
Nipple 21, also called point, first coating die 2
2 is a coating device for an optical fiber in which the second coating die 23 is combined.

When the optical fiber 1 exits the nipple hole 21a and is passed through the die hole 22a of the first coating die 22,
It contacts the first coating resin 30. The optical fiber 1 covered with the first coating resin 30 further comes into contact with the second coating resin 31 when exiting the die hole 22a and passing through the die hole 23a of the second coating die 23, The optical fiber 1 is pulled out through the die hole 23a to be coated with the double coating.

The first coating resin 30 is provided along the inner boundary between the nipple 21 and the first coating die 22 from the first coating resin introducing hole 21b provided on the outer periphery of the nipple 21. First reservoir chamber 24, first throttle portion 25, first
And is supplied to the portion between the outlet of the nipple hole 21a and the inlet of the die hole 22a. The second coating resin 31 is the second coating resin 31 provided on the outer periphery of the first coating die 22.
From the coating resin introducing hole 22b of the second coating die 22 along the inner boundary of the first coating die 22 and the second coating die 23.
Storage chamber 27, second throttle portion 28, second orthogonal flow path 29
And is supplied to a portion between the outlet of the die hole 22a and the inlet of the die hole 23a.

As described above, the first coating resin 30 is
After being temporarily stored in the storage chamber 24 of the optical fiber 1, it is sufficiently throttled by the first throttle portion 25, and as a result, a uniform flow is adjusted over the entire circumferential direction, and the optical fiber 1 is coated with a uniform thickness. I am able to In addition, the first orthogonal flow path 26 is connected to the outlet end surface of the nipple hole 21a and the die hole 22a.
Is formed between the inlet end faces of the optical fiber 1 and the optical fiber 1. Therefore, the first coating resin 30 is
Since it flows orthogonally to the optical fiber 1, the recirculation of the first coating resin 30 is suppressed, and the eccentricity of the optical fiber 1 due to the vibration caused thereby is prevented. Second coating resin 3
The same applies to No. 1 as well, in which coating with a uniform thickness is performed and eccentricity of the optical fiber 1 is prevented.

However, in the above-mentioned conventional technique, since the recirculation of the first and second coating resins 30 and 31 still remains, the outer diameter of the coating of the optical fiber 1 fluctuates.

FIG. 5 is an explanatory view of the recirculation of the coating resin in the prior art, FIG. 5 (A) is a partial sectional view, and FIG.
(B) is an explanatory view of the circumferential flow of the coating resin. In the figure,
The same parts as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted. 11 is a vortex, and 12 is a circumferential flow. The first coating resin 30 will be described, but the same applies to the second coating resin 31. In FIG. 5 (A), in the first orthogonal flow path 26, in the vicinity of the passage of the optical fiber 1 between the outlet of the nipple hole 21 a and the inlet of the die hole 22 a of the coating die 22, the first coating resin 30 is applied. When the optical fiber 1 is drawn, it is recirculated in the surrounding first coating resin 30, that is, the vortex 11 is generated.

As shown in FIG. 5B, this vortex 11 is
It occurs like a donut. A circular cross section appears when the donut-shaped body is cut along a plane including the central axis, but the vortex 11 draws a locus that goes around the circular cross section. Therefore, donut-shaped recirculation occurs. However, not only the vortex 11 is generated, but the circumferential flow 1 is generated around the central axis of the doughnut-shaped body.
There are two. This flow is a flow along the circumferential direction around the optical fiber 1. Therefore, the vortex 11 rotates around the optical fiber 1 along with the circumferential flow 12. The rotation direction changes with time and is indefinite, but the rotation cycle is the interval in the height direction of the first orthogonal flow path 26, the die hole 22a.
Is determined by structural dimensions such as the diameter and the taper angle, the feeding speed of the optical fiber 1, the viscosity of the first coating resin 30, and the like.
If there is a circumferential rotation under the condition of donut recirculation,
This donut recirculation attempts to rotate while maintaining its shape. Since this donut-shaped recirculation is generally not rotationally symmetric, the position of the optical fiber 1 is displaced due to this rotation. That is, the circumferential flow 12 causes a change in the outer diameter of the coating of the optical fiber 1.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and suppresses the phenomenon of rotation of the coating resin along the circumferential direction of the optical fiber, which occurs when the optical fiber is coated with the resin. Accordingly, it is an object of the present invention to provide an optical fiber coating apparatus and an optical fiber manufacturing method that suppress the variation of the outer diameter of the coating and reduce the variation of the non-uniform thickness ratio of the coating.

[0011]

According to a first aspect of the present invention, there is provided a coating resin which is orthogonal to the die hole between the nipple and a die having a tapered die hole whose diameter decreases toward the outlet. In an optical fiber coating device having a cross flow channel, a rotation suppressing wall for suppressing a circumferential flow of the coating resin generated in the cross flow channel is provided in the cross flow channel.

According to a second aspect of the invention, in the optical fiber coating apparatus according to the first aspect, at least one rotation inhibiting wall is provided on the end face of the die facing the orthogonal flow path from the outer periphery of the die. It is characterized by having toward the die hole.

According to a third aspect of the invention, in the optical fiber coating apparatus according to the first or second aspect, the height of the rotation inhibiting wall is 1/9 or more of the distance between the nipple and the die. It is characterized by being.

In the invention according to claim 4, the coating resin is supplied between the nipple and the die having the tapered die hole whose diameter decreases toward the outlet, in the circumferential direction orthogonal to the die hole, In a method of manufacturing an optical fiber, in which the coating resin is squeezed by a taper portion of the die and the resin is coated on an optical fiber passing through the die, a circumferential flow of the coating resin generated between the nipple and the die is suppressed. An optical fiber manufacturing method comprising:

[0015]

1 is a sectional view of an optical fiber coating apparatus according to an embodiment of the present invention, and FIG. 2 is a plan view of an upper end surface of the coating die. In the figure, the same parts as those in FIG. 2 is a nipple,
2a is a nipple hole, 3 is a coating die, 3a is a die hole, 3b
Is a rotation inhibiting wall, 4 is a sleeve, 4a is a coating resin introducing hole,
Reference numeral 5 is a reservoir chamber, 6 is a downward flow path, 7 is an orthogonal flow path, and 8 is a coating resin.

In this embodiment, in a coating apparatus for an optical fiber in which a nipple 2 and a coating die 3 are combined to coat an optical fiber 1 with a single-layer coating, an upper end surface of the coating die 3 is provided with a rotation inhibiting wall 3b. A plurality of planes are provided in the direction. When the optical fiber 1 exits the nipple hole 2a and is passed through the die hole 3a of the coating die 3, the die hole 3
A tapered die hole 3 that comes into contact with the coating resin 8 that is pressurized and supplied from the circumferential direction orthogonal to a and has a diameter that decreases toward the outlet.
When passing through a, the coating resin is squeezed and the coating resin 8 is applied and pulled out to form a single-layer coating on the optical fiber 1.

The shape of each member will be described. The nipple 2 is a thick, generally cylindrical shape having a nipple hole 2a in the center. The outer peripheral surface of the intermediate portion has a groove in the circumferential direction to form the reservoir chamber 5. In the lower adjacent portion of the reservoir chamber 5, the outer diameter is made slightly smaller than the inner diameter of the sleeve 4, which will be described later, and the downward flow passage 6 is formed along the boundary with the inner peripheral surface of the sleeve 4. The outer diameter of the outer peripheral surface near the lower end surface is tapered so that the outer diameter is in contact with the lower end surface. The lower end surface is a circular plane orthogonal to the nipple hole 2a. The nipple hole 2a is a cylindrical opening having a large inner diameter, a tapered opening, and a cylindrical opening having a small inner diameter in order from the top.

The coating die 3 is a thick, generally cylindrical shape having a die hole 3a in the center. On the upper end surface, as shown in FIG. 2, a rotation inhibiting wall 3b is provided on the plane orthogonal to the nipple hole 2a and the die hole 3a, and one is provided in the radial direction from the outer periphery of the coating die 3 toward the die hole 3a. As described above, four are provided in the illustrated example. The gap between the upper end surface and the lower end surface of the nipple 2 forms an orthogonal flow path 7 and intersects the optical fiber 1 at a right angle. At the lower end of the coating die 3, the outer diameter is increased and the protrusion is formed to form a step portion. The die hole 3a is a tapered portion and a parallel land portion whose inner diameter decreases in order from the top, and the inner diameter of the upper opening is larger than the inner diameter of the lower opening of the nipple hole 3a.

The sleeve 4 has a slightly larger inner diameter at the lower end to form a step, and the coating die 3 is attached from below. A coating resin introducing hole 4a is provided at one or a plurality of places, and the coating resin introducing hole 4a is connected to the reservoir chamber 8 of the nipple 2 in the assembled state.

The flow path of the coating resin 8 will be described. The coating resin 8 is supplied under pressure to the reservoir chamber 5 through the coating resin introducing hole 4a. It is supplied from the reservoir chamber 5 through the downward flow path 6 in the central direction of the orthogonal flow path 7, and reaches the portion between the outlet of the nipple hole 2a and the inlet of the die hole 3a. The coating resin 8 is
By the reservoir chamber 5 and the downward flow path 6, the flow is rectified into a uniform flow over the entire circumferential direction and guided to the orthogonal flow path 7, and the coating resin 8 flows perpendicularly to the optical fiber 1.

The lower end surface of the nipple 2 and the upper end surface of the coating die 3 forming the orthogonal flow path 7 impede the flow of the coating resin 8 toward the center in a range sufficiently wide relative to the hole diameter of the die hole 3a. With such a flat surface without irregularities, the recirculation of the coating resin 8 is not perfect, but can be suppressed to a considerable extent. Since the rotation inhibiting wall 3b is provided from the outer periphery of the coating die 3 toward the die hole 3a, it does not interfere with the flow of the coating resin 8 toward the center. In the structural example of this embodiment, the diameter of the lower end surface of the nipple 2 is equal to the cross flow path 7
Since the diameter is in the flat range, the diameter in the flat range can be made large with respect to the predetermined size of the entire optical fiber coating device. In addition, in order to rectify the coating resin 8 into a uniform flow over the entire circumferential direction, only one of the reservoir chamber 5 and the downward flow path 6 may be used, or a means other than these may be used.

FIG. 3 is a sectional view for explaining the recirculation of the coating resin in the embodiment of the present invention. In the figure, the same parts as those in FIG. 1 and FIG.
Since the orthogonal flow path 7 is formed by the lower end surface of the nipple 2 and the upper end surface of the coating die 3, the coating resin 8 is formed as in the prior art.
Since it flows orthogonally to the optical fiber 1, the vortex 11 of the recirculation of the coating resin 8 is suppressed to a considerable extent, and the eccentricity of the optical fiber 1 due to the vibration caused thereby is prevented. Further, the rotation inhibiting wall 3b provided in the orthogonal flow path 7
Is provided from the outer circumference of the coating die 3 toward the die hole 3a, and thus becomes an obstacle to the circumferential flow 12 of the vortex 11 of the recirculation of the coating resin 8 and suppresses the circumferential flow 12.
As a result, it is possible to suppress the variation in the outer diameter of the coating due to the circumferential flow 12 and reduce the variation in the non-uniform thickness ratio of the coating. In addition, the non-uniform wall thickness of the coating means a value that is b / a × 100 (%) in the cross section of the coating, where the maximum thickness of the coating is a and the minimum thickness is b.

Since the circumferential flow 12 becomes weaker as it goes out of the region near the optical fiber 1, the rotation inhibiting wall 3b is
It is more effective to bring it closer to the region near the optical fiber 1. However, if it is too close to the optical fiber 1, the coating resin 8
And the optical fiber 1 may be affected. When this influence is large, the distance from the center of the die hole 3a to the inner circumferential side end of the rotation inhibiting wall 3b may be set sufficiently larger than the radius of the die hole 3a. Even when the rotation suppressing wall 3b is provided at a position farther from the vicinity of the optical fiber 1 as described above, the circumferential flow is suppressed on the upstream side, and as a result, the circumferential flow 12 of the recirculation vortex 11 is also suppressed. You can

In order to suppress the circumferential flow 12, it may be possible to provide a partition inside the die hole 3a. However, it may affect the contact between the coating resin 8 and the optical fiber 1, and such a partition is not easy to manufacture. On the other hand, since the rotation inhibiting wall 3b is formed in the orthogonal flow path 7 such as the upper surface of the die 3, it is easy to manufacture. In addition,
The rotation inhibiting wall 3b does not necessarily have to be provided from the outer peripheral edge of the coating die 3, and may be provided in the radial direction of the center from a position having a diameter smaller than the outer diameter.

If the height of the rotation inhibiting wall 3b is 1/9 or more of the distance between the lower end face of the nipple 2 and the upper end face of the coating die 3, the action of inhibiting the circumferential flow 12 works, but it is 1/2. It is preferable that the content be set to the above, and if it is set to 70% or more, the deterrent effect becomes remarkable. When set to 100%, the rotation inhibiting wall 3b comes into contact with the lower end surface of the nipple 2. In this case, a pressure difference or a flow velocity difference may occur in the flow on both sides of the rotation inhibiting wall 3b, and the flow may be disturbed at the merging portion.

The rotation inhibiting wall 3b may be provided on the flat lower end surface side of the nipple 2, or on both sides of the upper end surface of the coating die 3 and the lower end surface of the nipple 2. The positions to be provided may be alternated in the circumferential direction. Alternatively, another member may be used in which the rotation inhibiting wall 3b is projected from the outer peripheral side toward the center in the orthogonal flow path 7 formed by the upper end surface of the coating die 3 and the lower end surface of the nipple 2.

As in the prior art described with reference to FIG. 4, when two coating dies are continuously used to apply a two-layer coating, even on the side where the second-layer coating is applied, Similarly, a rotation inhibiting wall may be provided in the second orthogonal flow path. Alternatively, for another nipple and die for applying the second layer of coating to the first layer of coated optical fiber,
A similar structure may be used.

[0028]

Example: 200 μ in the optical fiber 1 having an outer diameter of 125 μm φ
A single layer coating of mφ was applied. Four restraint walls 3b were provided as shown in FIG. By slightly changing the size of the die structure, the rotational speed of the circumferential flow 12 was changed, and at the same time, the variation of the outer diameter of the coating having the center value of 200 μmφ was changed. The outer diameter fluctuation at this time is ± 0.4 μm
Was within. When the rotation restraining wall 3b was not used and the circumferential flow was not obstructed, the outer diameter variation was within ± 1.5 μm.

[0029]

As is apparent from the above description, according to the first aspect of the present invention, the rotation suppressing wall for suppressing the circumferential flow of the coating resin generated in the cross flow passage is provided in the cross flow passage. Since the rotation-inhibiting wall inhibits the circumferential flow of the coating resin, the variation in the outer diameter of the coating can be suppressed, and the variation in the non-uniform thickness ratio of the coating can be reduced.

According to the invention described in claim 2, since at least one rotation inhibiting wall is provided on the end surface of the die facing the orthogonal flow path from the outer periphery of the die toward the die hole, only the end surface of the die is processed. Thus, the rotation inhibiting wall can be easily provided.

According to the third aspect of the invention, since the height of the rotation inhibiting wall is 1/9 or more of the distance between the nipple and the die, the rotation inhibiting wall inhibits the circumferential flow of the coating resin. Works.

According to the invention described in claim 4, since the flow of the coating resin in the circumferential direction generated between the nipple and the die is suppressed, the variation of the outer diameter of the coating is suppressed and the thickness of the coating is uniform. There is an effect that variation in the rate can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an optical fiber coating device according to an embodiment of the present invention.

FIG. 2 is a plan view of the upper end surface of the coating die of the optical fiber coating apparatus according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating recirculation of coating resin in the embodiment of the present invention.

FIG. 4 is a sectional view of a conventional optical fiber coating device.

5A and 5B are explanatory views of recirculation of a coating resin in a conventional technique, FIG. 5A is a partial sectional view, and FIG. 5B is an explanatory diagram of a circumferential flow of the coating resin.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical fiber, 2 ... Nipple, 3 ... Coating die, 4 ... Sleeve, 5 ... Reservoir chamber, 6 ... Downward flow path, 7 ... Orthogonal flow path, 8
... coating resin, 11 ... vortex, 12 ... circumferential flow, 21 ... nipple, 22 ... first coating die, 23 ... second coating die,
24 ... 1st reservoir chamber, 25 ... 1st throttle part, 26 ... 1st
Cross-flow channel, 27 ... second reservoir chamber, 28 ... second throttle part, 29 ... second cross-flow channel, 30 ... first coating resin, 3
1 ... Second coating resin.

Claims (4)

[Claims] 1. An optical fiber coating apparatus having an orthogonal flow path of a coating resin orthogonal to the die hole between a nipple and a die having a tapered die hole whose diameter decreases toward the outlet. A coating device for an optical fiber, characterized in that a rotation restraining wall for restraining a circumferential flow of the coating resin generated in an AC path is provided in the orthogonal flow path. 2. The optical fiber according to claim 1, wherein at least one rotation inhibiting wall is provided on an end surface of the die facing the orthogonal flow path from an outer circumference of the die toward the die hole. Coating equipment. 3. The optical fiber coating apparatus according to claim 1, wherein a height of the rotation inhibiting wall is 1/9 or more of a distance between the nipple and the die. 4. A coating resin is supplied between a nipple and a die having a tapered die hole whose diameter decreases toward the outlet, in a circumferential direction orthogonal to the die hole, and the coating is performed at a tapered portion of the die. In a method of manufacturing an optical fiber in which a resin is squeezed and an optical fiber passing therethrough is coated with the resin, an optical fiber characterized in that a circumferential flow of the coating resin generated between the nipple and the die is suppressed. Production method.