JP2005247608A - Method for manufacturing optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical fiber, by which fear of disconnection caused by uneven thickness of a coating applied on a bare optical fiber can be avoided, and in which the polarization mode dispersion (PMD) can be effectively reduced by making it possible to impart a sufficient twist to a fused part of an optical fiber preform. <P>SOLUTION: The method for manufacturing the optical fiber 2 includes a spinning process for forming the bare optical fiber 6 by fusion-spinning the optical fiber preform 4, a coating process for forming the optical fiber 2 by coating the bare optical fiber 6, and a twisting process for adding a twist to the fused part of the optical fiber preform 4 by imparting the twist to the optical fiber 2. When the twist is imparted to the optical fiber 2, the spinning tension T (gf) is set to satisfy following relation: 0.1×V+30≤T≤0.1×V+250 (wherein, V(m/min) is spinning linear velocity). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a spinning process in which an optical fiber preform is melt-spun to form a bare optical fiber, a coating process in which an optical fiber bare wire is coated to form an optical fiber strand, and a twist in the optical fiber strand. And a twisting step of twisting the melted portion of the optical fiber preform, and a method of manufacturing an optical fiber, and an optical fiber manufactured by the method of manufacturing the optical fiber It is about.

  Conventionally, in order to reduce PMD (polarization mode dispersion) in an optical fiber, when manufacturing an optical fiber by melting and spinning an optical fiber preform, a twist roller is in contact with the optical fiber. 2. Description of the Related Art An optical fiber twisting device including a twisting process in which a twist is applied to a melted portion of an optical fiber preform by swinging and twisting an optical fiber strand is known.

As an optical fiber twisting device, an appropriate place when spinning an optical fiber preform, for example, drawing an optical fiber preform, cooling, primary coating, and secondary coating, By installing an optical fiber twisting device and twisting the optical fiber with a twisting roller of the optical fiber twisting device, the optical fiber preform is twisted in the portion melted in the spinning furnace, and the optical fiber is twisted. The base material was melt drawn (for example, refer to Patent Documents 1 and 2).
Japanese Patent No. 3224235 Japanese Patent No. 3070603

  However, when twisting the optical fiber using the above optical fiber twisting device, depending on the spinning conditions such as spinning tension and spinning speed, it is not possible to effectively twist the optical fiber, There are cases where stable spinning cannot be performed, such as wire breakage during spinning.

  That is, when the spinning tension is low, when the optical fiber is twisted by the twisting roller, the optical fiber bare wire that has been subjected to the primary coating is shaken, and the thickness of the coating applied to the bare optical fiber When the thickness of the coating is significant, the bare optical fiber may come into contact with the parts such as the die and nipple of the coating apparatus and break. On the other hand, when the spinning tension is high, the viscosity at the melted portion of the optical fiber preform in the spinning furnace is high, so the twist resistance is large, and the twist imparted to the optical fiber by the optical fiber twisting device is large. Before being transmitted to the melted portion of the optical fiber preform, it stays in the bare optical fiber portion below the melted portion of the optical fiber preform, and the twisting force is canceled by the reverse twist transmitted thereafter, resulting in There was a risk that the twist would not sufficiently enter the melted portion of the optical fiber preform. In order to cope with this, if the twisting roller of the optical fiber twisting device is increased too much or the number of vibrations, etc., to add sufficient twist to the melted portion of the optical fiber preform, There has been a problem that slip occurs between the rollers and the frequency of disconnection of the optical fiber by the twisting roller increases.

  The present invention has been made in view of the problems as described above, and avoids the possibility that the thickness of the coating applied to the bare optical fiber becomes non-uniform and breaks, and in the molten portion of the optical fiber preform. It is an object of the present invention to provide a method of manufacturing an optical fiber that can be sufficiently twisted.

  For the above purpose, the present invention provides a spinning process for forming an optical fiber bare wire by melt spinning an optical fiber preform, and a coating process for coating the bare optical fiber to form an optical fiber strand. A method for manufacturing an optical fiber, comprising a twisting step of twisting the melted portion of the optical fiber preform by twisting the optical fiber, the twist being applied to the optical fiber In this case, when the spinning linear velocity is V (m / min), the spinning tension T (gf) is set to 0.1 × V + 30 ≦ T ≦ 0.1 × V + 250. It is a manufacturing method.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that the thickness of the coating applied to the bare optical fiber is non-uniform, and can avoid the possibility of disconnection due to non-uniform coating thickness.

  Further, according to the present invention, a sufficient twist can be applied to the melted portion of the optical fiber preform, and the number of oscillations or vibrations of the twisting roller of the optical fiber twisting device is increased so It is possible to prevent the frequency of disconnection of the fiber strands from increasing.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that the thickness of the coating applied to the bare optical fiber is non-uniform, and can avoid the possibility of disconnection due to non-uniform coating thickness. Furthermore, sufficient twisting can be applied to the melted portion of the optical fiber preform, and the frequency of disconnection of the optical fiber is increased by increasing the number of oscillations or vibrations of the twisting roller of the optical fiber twisting device. Can be prevented from increasing.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a spinning device 3 that manufactures an optical fiber 2 using an optical fiber twisting device 1 according to an embodiment of the present invention.

  A spinning device 3 according to an embodiment of the present invention is formed by spinning a spinning furnace 5 that heats and melt-spins an optical fiber preform 4 such as quartz glass, and is provided on the downstream side of the spinning furnace 5 and is spun. A cooling cylinder 7 that cools the bare optical fiber 6, a first primary coater 8 that is provided on the downstream side of the cooling cylinder 7 and applies a primary coating material to the bare optical fiber 6 cooled by the cooling cylinder 7; A first bridging cylinder 9 for irradiating and curing the applied primary coating material with ultraviolet rays, a second primary coater 10 for applying a secondary coating material to the primary coated optical fiber, and a applied secondary coating material A second bridging cylinder 11 that is cured by irradiating with ultraviolet rays, and an optical fiber 2 that is provided downstream of the second bridging cylinder 11 and is a secondary-coated optical fiber by a pair of twisting rollers or the like Optical fiber preform by twisting An optical fiber twisting device 1 for twisting a portion melted in the spinning furnace 5 in the above, and a downstream of the optical fiber twisting device 1, changing the moving direction of the optical fiber 2 and measuring the spinning tension. A turn pulley 12, a take-up tool 13 having a function of pulling the optical fiber preform 4, a dancer 14 that applies a winding tension to the optical fiber 2, and a winder 15 that winds up the optical fiber 2. Yes. The first primary coater 8, the first bridging cylinder 9, the second primary coater 10, and the second bridging cylinder 11 constitute a coating apparatus 16.

  As the optical fiber preform 4 used in the embodiment of the present invention, a gas phase axis method (VAD method), an external method (OVD method), an internal method (CVD method, MCVD method, PCVD method), Alternatively, it may be produced by any manufacturing method such as a rod-in-tube method.

  The optical fiber 2 manufactured by the optical fiber manufacturing method according to the embodiment of the present invention includes a single mode optical fiber, a dispersion shifted optical fiber, a cutoff shift optical fiber, a dispersion compensating optical fiber, and the like. There can be various types of optical fiber 2.

Hereinafter, experimental results of various experiments related to the present invention will be described.
Common conditions regarding the optical fiber twisting apparatus 1 in various experiments are as follows.
(Common conditions)
Optical fiber outer diameter: 125 μm
Coating material: Urethane = acrylate UV curable resin (both primary coating and secondary coating)
Coat diameter (optical fiber outer diameter): 250 μm
Spinning speed: 200 to 1000 m / min
(The spinning line speed is changed by changing the rotational speed of the take-up tool 13.)

  In this case, as the optical fiber twisting device 1, the optical fiber twisting device of the type shown in FIG. 4 in Japanese Patent No. 3224235, that is, a pair of twisting rollers sandwich the optical fiber strand between the rollers, and the optical fiber strand. An optical fiber twisting device that twists the optical fiber strands by moving in a direction perpendicular to the traveling direction of the optical fiber and in directions opposite to each other is used. Without limitation, various types of various optical fiber twisting apparatuses 1 can be applied.

FIG. 2 is a table showing changes in the frequency of breakage and the amount of twist during spinning when the spinning tension is changed for each of a plurality of spinning line speeds. FIG. 3 is a graph showing changes in the twist amount when the spinning tension is changed for each of a plurality of spinning linear speeds. FIG. 4 is a graph showing a change in twisting efficiency when the spinning tension is changed for each of a plurality of spinning linear velocities. FIG. 5 is a graph showing changes in the frequency of disconnection during spinning when the spinning tension is changed for each of a plurality of spinning line speeds.
The spinning tension is changed by changing the electric power applied to the heater of the spinning furnace 5. The spinning tension is measured at the turn pulley 12 portion.

In addition, the definition of the disconnection frequency during spinning is as follows.
That is, as described below, for example, when five optical fiber preforms for experiment are used, if the number of breaks is 0, the number of spinning is 5 and the breakage frequency (%) = 0/5 × 100 = 0. If the number of breaks is 1, one broken fiber optic preform is spun before breakage (breakage during this spinning) and re-spun after breakage (not broken during this re-spinning). This means that spinning was performed twice. Therefore, the number of spinning times (4 times) of the other four optical fiber preforms that have not been broken is added to the total number of spinning times, and the breaking frequency (%) = 1/6 × 100≈17.
As described above, it is defined as disconnection frequency (%) = number of disconnections / (number of optical fiber preforms used + number of disconnections) × 100. However, the disconnection frequency of 100% indicates that it was difficult to disconnect and spin each time spinning.

  In addition, the measurement of torsion is carried out by measuring the outer diameter of the bare optical fiber from two different directions in the plane perpendicular to the length direction of the bare optical fiber, as in JP-A-2001-31440. It is performed by continuously measuring along the length direction of Here, the amount of twist is the number of times the bare optical fiber per 1 m is twisted.

  The theoretical twist amount calculated according to the conditions of the optical fiber twisting apparatus used in this experimental example is [theoretical twist amount] = {[translation distance mm] × [frequency rpm] × 2} / {[optical fiber strand] Outer circumference mm] × [linear velocity m / min]}.

  Ideally, the amount of twist applied to the optical fiber should be the theoretical amount of twist. However, in reality, twist resistance due to viscosity occurs in the glass of the molten portion of the optical fiber preform to which twist is applied. In addition, due to this twisting resistance, the twisting force may be offset by the reverse rotation twist transmitted before the glass is twisted. This depends on the distance between the optical fiber twisting device and the melted portion of the optical fiber preform, and is easily canceled when it is long, and is not easily canceled when it is short. Furthermore, the twisting torque applied by the optical fiber twisting device is slipped due to the frictional force between the twisting roller and the optical fiber strand, and may not be transmitted 100%. For these reasons, the twisting efficiency (the amount of twist actually added to the theoretical amount of twist) is not 100%. In this spinning device configuration, the maximum twisting efficiency is 50%. On the other hand, the twisting efficiency is reduced by the spinning tension, and if the spinning tension is extremely high, the efficiency is further reduced.

(Experimental example 1)
The spinning tension is changed in five stages (40, 50, 200, 270, 280 gf) at a spinning linear speed of 200 m / min, and five optical fiber preforms 4 are respectively used for each of the five spinning tensions. The fiber strand 2 was spun while performing a twisting process for applying twist. The condition of the optical fiber twisting device is that the roller translational distance (the distance that the twisting roller moves in the direction perpendicular to the traveling direction of the optical fiber strand) is 15 mm, and the roller frequency (the twisting roller is the traveling direction of the optical fiber strand). The number of reciprocations in the vertical direction per minute) was 180 rpm (rotation / min).
Using the above equation, the theoretical torsion amount in Experimental Example 1 is found to be 34 rotations / min. The maximum value of the actual twist amount is 17 rotations / min.
The disconnection frequency, twist amount, and twist efficiency during spinning are shown in FIGS.

  As can be seen from FIGS. 2 to 5, when spinning with a spinning tension of 40 gf, the disconnection frequency during spinning was 100%, and 100% was disconnected, and the optical fiber 2 could not be manufactured. When spinning at a spinning tension of 50 gf, the disconnection frequency during spinning was 0%, the twisting amount was 16 revolutions / m, and the twisting efficiency was 47%. Thus, good results were obtained. When spinning at a spinning tension of 200 gf, the disconnection frequency during spinning was 0%, the twisting amount was 15 revolutions / m, and the twisting efficiency was 44%. Thus, good results were obtained. When spinning with a spinning tension of 270 gf, the disconnection frequency during spinning was 17%, the twisting amount was 14 revolutions / m, and the twisting efficiency was 41%. Thus, good results were obtained. When spinning at a spinning tension of 280 gf, the breakage frequency during spinning is 50%, the twist amount is 8 revolutions / m, the breakage frequency during spinning is high, and the twist amount is also higher than when the spinning tension is 270 gf. The twisting efficiency was 24%, and no reasonable results were obtained with respect to any of the breakage frequency, twisting amount, and twisting efficiency during spinning.

From the above results, it was found that when the spinning tension was less than 50 gf, the disconnection frequency during spinning was 100%, and the optical fiber 2 could not be manufactured. On the other hand, the twisting amount and twisting efficiency decrease as the spinning tension increases, and it is recognized that the spinning tension exceeds 270 gf. It was found that the yield was 50% and the yield was very bad.
From the above, it was found that the minimum spinning tension T1 was 50 gf and the maximum spinning tension T2 was 270 gf when the spinning linear speed was 200 m / min.

(Experimental example 2)
The spinning tension is changed in five stages (50, 60, 180, 280, 290 gf) at a spinning linear velocity of 300 m / min, and five optical fiber preforms 4 for each of the five stages of spinning tension. The fiber strand 2 was spun while performing a twisting process for applying twist. As conditions for the optical fiber twisting apparatus, the roller translational distance was 15 mm, and the roller frequency was 220 rpm.
The theoretical torsion amount in Experimental Example 2 is 28 rotations / min. The maximum value of the actual twist amount is 14 rotations / min. The disconnection frequency, twist amount, and twist efficiency during spinning at that time are shown in FIGS.

  As can be seen from FIGS. 2 to 5, when spinning at a spinning tension of 50 gf, the disconnection frequency during spinning was 100%, and 100% was disconnected, and the optical fiber 2 could not be manufactured. When spinning at a spinning tension of 60 gf, the breakage frequency during spinning was 0%, the twisting amount was 13 revolutions / m, and the twisting efficiency was 46%. Thus, good results were obtained. When spinning at a spinning tension of 180 gf, the disconnection frequency during spinning was 0%, the twisting amount was 12 revolutions / m, and the twisting efficiency was 43%. Thus, good results were obtained. When spinning with a spinning tension of 280 gf, the disconnection frequency during spinning was 17%, the twisting amount was 11 revolutions / m, and the twisting efficiency was 39%. When spinning at a spinning tension of 290 gf, the breakage frequency during spinning was 54%, the twisting amount was 7 revolutions / m, the breaking frequency during spinning was high, and the twisting amount was also higher than when the spinning tension was 280 gf. The twisting efficiency was 25%, and no reasonable result was obtained for any of the breakage frequency, twisting amount, and twisting efficiency during spinning.

From the above results, it was found that when the spinning tension was less than 60 gf, the disconnection frequency during spinning was 100%, and the optical fiber 2 could not be manufactured. On the other hand, the amount of twist and twist efficiency decrease as the spinning tension increases, and it is understood that when the spinning tension exceeds 280 gf, the twisting frequency and twisting efficiency decrease significantly. It was found that the yield was 54%, which was very poor.
From the above, it was found that the minimum spinning tension T1 was 60 gf and the maximum spinning tension T2 was 280 gf when the spinning linear speed was 300 m / min.

(Experimental example 3)
The spinning tension is changed in five stages (80, 90, 230, 310, 320 gf) at a spinning linear speed of 600 m / min, and five optical fiber preforms 4 are respectively used for each of the five stages of spinning tension. The fiber strand 2 was spun while performing a twisting process for applying twist. The conditions of the optical fiber twisting device were a roller translation distance of 15 mm and a roller frequency of 350 rpm.
The theoretical torsional amount in Experimental Example 3 is 22 rotations / min. The maximum value of the actual twist amount is 11 revolutions / min. The disconnection frequency, twist amount, and twist efficiency during spinning are shown in FIGS.

  As can be seen from FIGS. 2 to 5, when spinning at a spinning tension of 80 gf, the disconnection frequency during spinning was 100%, and 100% was disconnected, and the optical fiber 2 could not be manufactured. When spinning at a spinning tension of 90 gf, the breakage frequency during spinning was 0%, the twisting amount was 11 revolutions / m, and the twisting efficiency was 50%. Thus, good results were obtained. When spinning at a spinning tension of 230 gf, the disconnection frequency during spinning was 0%, the twisting amount was 10 revolutions / m, and the twisting efficiency was 45%. Thus, good results were obtained. When spinning with a spinning tension of 310 gf, the disconnection frequency during spinning was 17%, the twisting amount was 9 revolutions / m, and the twisting efficiency was 41%. When spinning at a spinning tension of 320 gf, the breakage frequency during spinning is 58%, the twist amount is 5 revolutions / m, the breakage frequency during spinning is high, and the twist amount is also higher than when the spinning tension is 310 gf. The twisting efficiency was 23%, and no reasonable results were obtained with respect to any of the breakage frequency, twisting amount, and twisting efficiency during spinning.

From the above results, it was found that when the spinning tension was less than 90 gf, the disconnection frequency during spinning was 100%, and the optical fiber 2 could not be manufactured. On the other hand, the twisting amount and twisting efficiency decrease as the spinning tension increases, and it is understood that when the spinning tension exceeds 310 gf, the twisting frequency and twisting efficiency decrease significantly when the spinning tension exceeds 310 gf. It was 58% and it was understood that the yield was very bad.
From the above, it was found that the minimum spinning tension T1 was 90 gf and the maximum spinning tension T2 was 310 gf when the spinning linear speed was 600 m / min.

(Experimental example 4)
At a spinning linear speed of 1000 m / min, the spinning tension is changed in five stages (120, 130, 250, 350, 360 gf), and five optical fiber preforms 4 for each of the five stages of spinning tension. The fiber strand 2 was spun while performing a twisting process for applying twist. The conditions of the optical fiber twisting apparatus were a roller translation distance of 30 mm and a roller frequency of 250 rpm.
The theoretical torsion amount in Experimental Example 4 is 19 rotations / min. The maximum value of the actual twist amount is about 9 revolutions / min. The disconnection frequency, twist amount, and twist efficiency during spinning are shown in FIGS.

  As can be seen from FIGS. 2 to 5, when spinning at a spinning tension of 120 gf, the disconnection frequency during spinning was 100%, and 100% was disconnected, and the optical fiber 2 could not be manufactured. When spinning at a spinning tension of 130 gf, the disconnection frequency during spinning was 0%, the twisting amount was 9 revolutions / m, and the twisting efficiency was 47%. Thus, good results were obtained. When spinning at a spinning tension of 250 gf, the disconnection frequency during spinning was 0%, the twisting amount was 8 revolutions / m, and the twisting efficiency was 42%. Thus, almost good results were obtained. Further, when spinning at a spinning tension of 350 gf, the disconnection frequency during spinning was 17%, the twisting amount was 8 revolutions / m, and the twisting efficiency was 42%. Thus, good results were obtained. When spinning at a spinning tension of 360 gf, the breakage frequency during spinning is 62%, the twist amount is 2 revolutions / m, the breakage frequency during spinning is high, and the twist amount is also higher than when the spinning tension is 350 gf. The twisting efficiency was 11%, and no reasonable result was obtained for any of the breakage frequency, twisting amount, and twisting efficiency during spinning.

From the above results, it was found that when the spinning tension was less than 130 gf, the disconnection frequency during spinning was 100%, and the optical fiber 2 could not be manufactured. On the other hand, the twisting amount and twisting efficiency decrease as the spinning tension increases, and it is understood that when the spinning tension exceeds 350 gf, the twisting frequency and the twisting efficiency decrease significantly when the spinning tension exceeds 350 gf. It was 58% and it was understood that the yield was very bad.
From the above, it was found that the minimum spinning tension T1 was 130 gf and the maximum spinning tension T2 was 350 gf when the spinning linear velocity was 1000 m / min.

  From the above experimental results shown in FIGS. 2 to 5, the minimum spinning tension T1 is 50 gf when the spinning line speed is 200 m / min, and the minimum spinning tension T1 is 60 gf when the spinning line speed is 300 m / min. When the speed is 600 m / min, the minimum spinning tension T1 is 90 gf, and when the spinning linear speed is 1000 m / min, the minimum spinning tension T1 is 130 gf. From these results, T (gf) ≧ 0.1 × V (m / min) +30 can be derived.

  That is, when twisting the optical fiber 2 and the spinning line speed is V (m / min), if the spinning tension T (gf) is T ≧ 0.1 × V + 30, It was found that the thickness of the coating applied to the bare fiber can be prevented from becoming non-uniform, and the possibility of disconnection due to the non-uniform thickness of the coating can be avoided.

  From the above experimental results shown in FIGS. 2 to 5, the maximum spinning tension T1 is 270 gf when the spinning line speed is 200 m / min, and the maximum spinning tension T1 is 280 gf when the spinning line speed is 300 m / min. When the speed is 600 m / min, the maximum spinning tension T1 is 310 gf, and when the spinning linear speed is 1000 m / min, the maximum spinning tension T1 is 350 gf. From these results, T (gf) ≦ 0.1 × V (m / min) +250 can be derived.

  That is, if T ≦ 0.1 × V + 250, a sufficient twist can be applied to the melted portion of the optical fiber preform 4, and the oscillation frequency or frequency of the torsion roller 22 of the optical fiber twisting device 1 or the like can be increased. It has been found that it is possible to prevent an excessive increase in the frequency of disconnection of the optical fiber 2.

  The experimental results shown in FIGS. 2 to 5 are described when the spinning linear velocity is 200 to 1000 m / min. However, even when the spinning linear velocity exceeds 1000 m / min, 0.1 × V + 30. When ≦ T ≦ 0.1 × V + 250 is satisfied, it has been confirmed that good results can be obtained with respect to the disconnection frequency, twist amount, and twist efficiency of the optical fiber 2.

It is the schematic which shows the spinning apparatus by embodiment of this invention. It is a figure which shows the experimental result in the spinning apparatus by embodiment of this invention. It is a figure which shows the experimental result in the spinning apparatus by embodiment of this invention. It is a figure which shows the experimental result in the spinning apparatus by embodiment of this invention. It is a figure which shows the experimental result in the spinning apparatus by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical fiber twisting device, 2 ... Optical fiber strand, 3 ... Spinning device, 4 ... Optical fiber preform, 5 ... Spinning furnace, 6 ... Bare optical fiber, 7 ... Cooling cylinder, 8 ... 1st primary coater, 9 ... 1st bridge, 10 ... 2nd primary coater, 11 ... 2nd bridge, 12 ... Turn pulley, 13 ... Take-off tool, 14 ... Dancer, 15 ... ··· Winding device, 16 ··· Coating equipment

Claims (1)

A spinning process in which an optical fiber preform is melt-spun to form an optical fiber bare wire, a coating process in which the optical fiber bare wire is coated to form an optical fiber strand, and a twist is applied to the optical fiber strand A twisting step of twisting the melted portion of the optical fiber preform, and a manufacturing method of an optical fiber, comprising:
When twisting the optical fiber, when the spinning linear velocity is V (m / min), the spinning tension T (gf) is
0.1 × V + 30 ≦ T ≦ 0.1 × V + 250
A method for manufacturing an optical fiber.

Images