JP2023117701A - Manufacturing method of optical fiber core wire - Google Patents

Abstract

To provide a manufacturing method of an optical fiber core wire capable of improving a yield in forming a coloring layer.SOLUTION: A manufacturing method of an optical fiber core wire includes: a coloring process of passing an optical fiber strand through a passage port of a coloring die where a coloring resin is supplied from a supply port to form a coloring layer over a circumference of the optical fiber strand to obtain an optical fiber core wire; and a stand-by process of arranging the coloring die on a pass line of the optical fiber strand in the coloring process under a linear velocity stop state of the optical fiber strand. In the stand-by process, a resin pressure of the coloring resin in the coloring die is a positive pressure, and the coloring process is started while the resin pressure of the coloring resin is the positive pressure.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present disclosure relates to a method for manufacturing an optical fiber core wire.

Patent Literature 1 discloses a method of forming a colored layer of an optical fiber by applying a colored resin to the outer periphery of the optical fiber that is let out.

JP 2010-197455 A

Patent Literature 1 discloses controlling the resin pressure of the colored resin in the coloring die when applying the colored resin to the outer circumference of the optical fiber. Specifically, when the linear velocity of the optical fiber passing through the coloring die is zero, the resin pressure is also zero. When the linear speed of the optical fiber passing through the coloring die starts to increase, the resin pressure also increases. When the linear speed of the optical fiber passing through the coloring die reaches a steady state, the resin pressure is also controlled to maintain a predetermined value.

By the way, in an optical fiber core wire obtained by applying a colored resin to an optical fiber bare wire, a defective molded part such as a bump may be formed in the colored layer.

The present disclosure provides an optical fiber core wire manufacturing method that improves the yield in forming a colored layer.

A method for manufacturing an optical fiber core wire according to an aspect of the present disclosure includes:
a coloring step of forming a colored layer on the outer periphery of the optical fiber strand by passing the optical fiber strand through a passage port of a coloring die to which a colored resin is supplied from a supply port to produce an optical fiber core;
a waiting step of arranging the coloring dice on a pass line through which the optical fiber is passed in the coloring step in a state where the line speed of the optical fiber is stopped;
In the standby step, the resin pressure of the colored resin in the colored die is a positive pressure,
The coloring process is started while the resin pressure of the colored resin is positive.

Advantageous Effects of Invention According to the present disclosure, it is possible to provide a method for manufacturing an optical fiber core wire that improves the yield in forming colored layers.

FIG. 1 is a schematic diagram of an optical fiber core wire manufacturing apparatus. FIG. 2 is a diagram showing the relationship between drawing speed and time in the manufacturing method of the optical fiber core wire and the relationship between the resin pressure and time in the manufacturing method of the optical fiber core wire and the comparative example.

(Description of Embodiments of the Present Disclosure)
First, the embodiments of the present disclosure are listed and described.
A method for manufacturing an optical fiber core wire according to an aspect of the present disclosure includes:
(1) Coloring in which an optical fiber core wire is produced by forming a colored layer on the outer periphery of the optical fiber strand by passing the optical fiber strand through a passage port of a coloring die to which a colored resin is supplied from a supply port. process and
a waiting step of arranging the coloring dice on a pass line through which the optical fiber is passed in the coloring step in a state where the line speed of the optical fiber is stopped;
In the standby step, the resin pressure of the colored resin in the colored die is a positive pressure,
The coloring process is started while the resin pressure of the colored resin is positive.
According to the above configuration, even in the standby process, the resin pressure of the colored resin in the colored dies is positive, so that the colored resin in the colored dies can be prevented from flowing back toward the supply port. When the colored resin flows backward in the direction of the supply port in the colored die, air is entrained in the reverse flow, which causes air bubbles to be generated inside the colored resin. If a colored resin with air bubbles floating inside is applied in the coloring process, it may cause the formation of a defective molded part. However, in the manufacturing method of the optical fiber core wire of the present disclosure, since the backflow of the colored resin is less likely to occur, air bubbles are less likely to be generated, the occurrence of defective molded parts can be suppressed, and the yield is improved.

(2) In the method for manufacturing an optical fiber core wire according to (1) above, the height of the liquid level of the colored resin in the supply tank that supplies the colored resin to the colored die is determined by the level of the colored resin in the colored die. It may be higher than the height of the liquid surface.
According to the above configuration, since the liquid level of the pre-colored resin in the supply tank is higher than the liquid level of the colored resin in the coloring die, the resin pressure of the colored resin in the coloring die naturally becomes a positive pressure. Therefore, it is possible to realize an optical fiber core wire manufacturing method that suppresses the occurrence of defective molded portions with a simple configuration.

(3) In the standby step of the method for manufacturing a coated optical fiber according to (1) or (2) above, the optical fiber may be stopped while passing through the passage opening.
According to the above configuration, since the optical fiber is stopped in a state in which the optical fiber is passed through the passage, even if the resin pressure of the colored resin in the coloring die is positive, Colored resin is hard to overflow.

(4) In the method for manufacturing an optical fiber core wire according to any one of (1) to (3) above,
The passage port has a wire entry port through which the optical fiber strand enters the coloring die,
In the standby step, a cover portion that closes the wire inlet may be attached to the coloring dice.
According to the above configuration, since the cover portion is provided at the wire entrance to close the gap between the optical fiber and the coloring die, the resin pressure of the coloring resin is applied to the coloring die. Also, the colored resin is less likely to overflow from the inlet port.

(5) In the method for manufacturing an optical fiber core wire according to any one of (1) to (4) above,
The passage port has a wire entrance port through which the optical fiber strand enters the coloring die,
The colored resin overflowing from the inlet may be recovered.
According to the above configuration, even if the colored resin overflows from the coloring die, the colored resin can be reused by recovering the overflowed colored resin.

(6) In the method for manufacturing an optical fiber core wire according to (5) above, the temperature of the colored resin inside the coloring die in the standby step is adjusted to the temperature of the colored resin inside the coloring die in the coloring step. You may control so that it may be lowered more.
According to the above configuration, by controlling the temperature of the colored resin inside the coloring die so that the viscosity of the colored resin in the standby process is higher than the viscosity of the colored resin in the coloring process, coloring is performed even in a pressurized state. Colored resin is less likely to overflow from the die.

(Details of embodiments of the present disclosure)
A specific example of a method for manufacturing an optical fiber core wire according to an embodiment of the present disclosure will be described below with reference to the drawings. The present invention is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

Also, in the description of the present embodiment, for convenience of description, the term “vertical direction” will be referred to as appropriate. Here, the "vertical direction" is a direction including the "upward direction" and the "downward direction". Reference numeral U shown in the drawings described below indicates an upward direction. Symbol D indicates the downward direction.

FIG. 1 is a schematic diagram of an apparatus 1 for manufacturing an optical fiber core wire G2. The manufacturing apparatus 1 for the optical fiber G2 applies the method for manufacturing the optical fiber G2 according to the present embodiment in the coloring step of coating the outer circumference of the optical fiber G1 with a colored resin.

As shown in FIG. 1, an apparatus 1 for manufacturing an optical fiber G2 includes a die unit 2 for applying a colored resin to the optical fiber G1, an ultraviolet irradiation device 3 for applying ultraviolet rays to the applied colored resin, It has A guide roller 11 is attached above the die unit 2 to guide the optical fiber strand G1 fed from a feeding bobbin (not shown) to the die unit 2 . A guide roller 12 is provided below the ultraviolet irradiation device 3 to guide the optical fiber core G2 formed by irradiation with ultraviolet rays to a take-up bobbin (not shown).

The dice unit 2 includes coloring dice 23 , a receiving portion 22 and a cover portion 21 . The cover portion 21, the receiving portion 22, and the coloring dice 23 are arranged in this order in the direction in which the optical fiber strand G1 enters the die unit 2 (the direction in which it advances from top to bottom). It is desirable that the cover portion 21 be attached so as to cover a wire inlet 23a, which will be described later. The cover portion 21 is provided with a hole for passing the optical fiber wire G1. The receiving portion 22 includes an upper resin reservoir 221 capable of accommodating colored resin therein. Similarly, the coloring die 23 has a lower resin pool 231 in which a coloring resin can be accommodated. The coloring die 23 has a wire inlet 23a, which is a passage through which the optical fiber strand G1 can be inserted. The upper resin pool 221 and the lower resin pool 231 are in communication with each other through the wire inlet 23a. The coloring die 23 is further provided with an output port 23b, which is a passage port through which the optical fiber wire G1 can be output.

A supply tank ST is connected to the coloring dice 23 via a supply pipe SP. The supply tank ST supplies the colored resin stored inside by flowing it into the lower resin reservoir 231 from the supply port of the coloring die 23 . The supply tank ST is preferably arranged such that the liquid level F2 of the colored resin in the supply tank ST is higher than the liquid level F1 of the colored resin in the coloring die 23 . However, when the colored resin overflowing from the inside of the coloring die 23 can be temporarily held by the receiving portion 22 as shown in FIG. regarded as the liquid surface.

As the colored resin applied to the optical fiber strand G1, for example, an ultraviolet curable resin containing a coloring pigment or the like is used. The colored resin supplied from the supply tank ST is applied to the outer periphery of the optical fiber strand G1 passing through the coloring die 23 . In this example, the optical fiber G1 is a state in which a coating layer (for example, a primary resin and a secondary resin) is coated on the outer periphery of a glass fiber formed by drawing a preform (optical fiber base material). means a fiber of

The upper resin reservoir 221 of the receiving portion 22 can temporarily store the colored resin overflowing from the coloring die 23 . The upper resin pool 221 is connected via a recovery pipe DP to a recovery tank DT for recovering the temporarily stored colored resin. The recovery tank DT is preferably arranged such that the liquid level F3 of the colored resin in the recovery tank DT is lower than the liquid level F1 of the colored resin in the coloring die 23 .

A pressure gauge 24 is provided at the connecting portion between the coloring die 23 and the supply pipe SP. A heater 25 is attached to a part of the supply pipe SP. The heater 25 is connected to the controller 26 . By controlling the temperature of the heater 25 , the controller 26 can raise or lower the temperature of the colored resin inside the coloring die 23 .

The controller 26 may be connected to, for example, a capstan (not shown) provided downstream of the guide roller 12 in addition to the heater 25 . For example, the controller 26 may change the running speed (line speed) of the optical fiber strand G1 in the manufacturing apparatus 1 by controlling the capstan. Further, the control unit 26 may be connected to a pump (not shown) that feeds the coloring resin from the supply tank ST toward the coloring dice 23 to control the pressure inside the coloring dice 23 .

The ultraviolet irradiation device 3 is a device for curing the colored resin by irradiating the optical fiber strand G1 coated with the colored resin with ultraviolet rays. The ultraviolet irradiation device 3 is composed of, for example, a single-stage or multiple-stage ultraviolet irradiation furnace.

Next, an optical fiber manufacturing method using the manufacturing apparatus 1 will be described.
First, at the start of the coloring process, which is a part of the optical fiber manufacturing process, the optical fiber strand G1 begins to be fed from the feeding bobbin, enters the coloring die 23, and is placed on the pass line to the winding bobbin. A wire G1 is set.

When the coloring process is started, the drawing speed of the optical fiber G1 becomes greater than zero and increases to a predetermined drawing speed. A colored resin supplied from a supply tank ST through a supply pipe SP is applied to the outer periphery of the optical fiber strand G1 that has entered the coloring die 23 . The optical fiber strand G<b>1 coated with colored resin is output from the colored die 23 .

The optical fiber strand G1 output from the coloring die 23 is sent to the ultraviolet irradiation device 3 . When the optical fiber G1 fed into the ultraviolet irradiation device 3 (irradiation furnace) is irradiated with ultraviolet rays, the colored resin applied to the outer periphery of the optical fiber G1 is cured to form a colored layer. be done. The optical fiber core G<b>2 manufactured in this manner is wound up on a winding bobbin (not shown) via a guide roller 12 after being output from the ultraviolet irradiation device 3 .

When the colored layer is formed with respect to the predetermined length, the drawing speed of the optical fiber G1 is reduced to complete the coloring process. When the drawing speed of the optical fiber G1 becomes 0 (that is, when the drawing speed is stopped), the process shifts to a standby step. In the standby process, for example, replacement of the bobbin for feeding the optical fiber G1 can be performed. The waiting process may take several tens of minutes or more, for example. For example, even when the bobbin for feeding the optical fiber G1 is exchanged, the coloring die 23 remains arranged on the pass line in the waiting process.

Further, in the standby step, the optical fiber strand G1 may be stopped while being passed through the passage openings (the entrance opening 23a and the exit opening 23b) provided in the coloring die 23. FIG. For example, when the bobbin for feeding the optical fiber G1 is exchanged, the optical fiber G1 is cut before and after the coloring die 23 so that the optical fiber G1 is separated from the entrance 23a and the exit. It is preferable to maintain the state of being passed through the port 23b as much as possible.
Note that a state in which the optical fiber G1 is not on the pass line due to, for example, replacement of the pay-out bobbin also corresponds to the line speed stop state.

Furthermore, the controller 26 may change the control of the operation of the heater 25 between the coloring process and the standby process. For example, the control unit 26 may monitor the temperature of the colored resin inside the coloring die 23 and operate the heater 25 so that the temperature of the colored resin in the standby process is lower than the temperature of the colored resin in the coloring process. good.

(Supply pressure of colored resin)
Next, the supply pressure of the coloring resin to the coloring die 23 according to this embodiment (hereinafter referred to as resin pressure) will be described. FIG. 2 is a diagram showing the relationship between the drawing speed and time in the method for manufacturing the optical fiber core G2 and the relationship between the resin pressure and time in the manufacturing method for the optical fiber core G2 and the comparative example. The resin pressure is the gauge pressure of the coloring resin at the supply port of the coloring die 23 . The resin pressure is measured by a pressure gauge 24 attached between the coloring die 23 and the supply pipe SP. Alternatively, it may be calculated from the difference between the height of the liquid surface F2 of the colored resin in the supply tank ST and the height of the liquid surface F1 of the colored resin in the coloring die 23, the density of the colored resin, and the gauge pressure inside the supply tank ST. . 2, the solid line graph shows the resin pressure when the optical fiber core G2 is manufactured using the method of the present embodiment, and the dashed line graph shows the resin pressure obtained by the method of the comparative example described later. It shows the resin pressure when the optical fiber core wire G2 is manufactured using this.

At time t0, the coloring process is started. When the coloring process is started, the drawing speed of the optical fiber G1 increases from 0 to the drawing speed V1 between time t0 and time t1. Accordingly, the resin pressure is increased from pressure P1 (>0) to pressure P2.
From time t1 to time t2, the optical fiber G1 travels at a constant linear velocity V1, and the resin pressure is maintained at a constant pressure P2.
From time t2 to time t3, the drawing speed of the optical fiber G1 is reduced from the drawing speed V1 to 0 in order to complete the coloring process. Accordingly, the resin pressure is reduced from pressure P2 to pressure P1.
When the coloring process ends at time t3, the process shifts to the standby process. In the standby process, the line speed of the optical fiber G1 is 0, but it is desirable to maintain the resin pressure at P1. That is, the resin pressure is positive even in the standby process.

When the coloring process starts again at time t4, the drawing speed and resin pressure of the optical fiber G1 are controlled until time t7 in the same manner as in the coloring process from time t0 to time t3.

At time t7, the standby process is started again. Similar to the standby process from time t3 to time t4, in the standby process from time t7 to time t8, the linear velocity of the optical fiber G1 is 0, but the resin pressure is maintained at pressure P1. In other words, the resin pressure is positive during the standby process from time t7 to time t8.

When the coloring process is resumed at time t8, the resin pressure remains positive as at time t4. Thereafter, when the coloring process and the standby process are repeated, the coloring process from time t0 to time t3 and the standby process from time t3 to time t4 are similarly performed with the linear speed and resin pressure of the optical fiber G1. controlled.

(Comparative example)
Next, a comparative example with the above example will be described. The comparative example is based on the method for manufacturing the optical fiber core wire described in Patent Document 1. In the comparative example, the drawing speed of the optical fiber at each time t0 to t9 is the same as that in the example. However, the resin pressure at each time t0 to t9 differs from the embodiment. For example, the resin pressure is zero during the standby process from time t3 to time t4 or from time t7 to time t8. Further, as shown by the dashed line graph in FIG. 2, the coloring process is started in a state where the resin pressure is not positive at t0, t4, and t8, which are the start times of the coloring process.

By the way, when a colored resin is applied to the optical fiber strand, a defective molded portion such as a bump may be formed. Since the optical fiber core wire on which the defective molded portion is formed is discarded, it is essential to reduce the defective molded portion in order to improve the yield.

The inventors have found that the formation of defective molded parts can be reduced by devising the standby process instead of the coloring process.
More specifically, the inventors have found that defective molded parts such as bumps are caused by air bubbles floating in the colored resin. As in the comparative example, if the resin pressure is zero in the standby process, the colored resin may flow back through the supply pipe, and air may be entrained in the colored resin. The air entrained in the colored resin becomes air bubbles and floats inside the colored resin. If the coloring process is performed in this state, a defective colored layer is formed.

According to the method for manufacturing the optical fiber core G2 of the present embodiment, the resin pressure of the colored resin in the colored die 23 is positive even in the standby process, so the colored resin in the colored die 23 flows back toward the supply port. can be suppressed, and air bubbles in the colored resin are less likely to occur. Since the coloring process is started while maintaining this state, the occurrence of defective molded parts in the coloring process can be suppressed, and the yield is improved.

In the method for manufacturing the optical fiber core G2 of the present embodiment, the height of the liquid level F2 of the colored resin in the supply tank ST is higher than the height of the liquid level F1 of the colored resin in the coloring die 23 . As a result, the colored resin is automatically supplied from the supply tank ST to the coloring die 23, and the resin pressure of the colored resin in the coloring die 23 naturally becomes a positive pressure. Therefore, it is possible to realize a method of manufacturing the optical fiber G2 that suppresses the occurrence of defective molded portions with a simple configuration.

In the standby step of the method for manufacturing the optical fiber core G2 of the present embodiment, the optical fiber G1 is stopped while passing through the passage opening. As a result, even if the resin pressure of the colored resin in the colored die 23 is positive, the colored resin is less likely to overflow from the passage port.

In the method of manufacturing the optical fiber core G2 of the present embodiment, the covering portion 21 is attached to the coloring die 23 so as to cover the wire entrance 23a. As a result, even if the resin pressure in the coloring die 23 is positive, the colored resin is less likely to overflow from the wire inlet 23a.

In the method of manufacturing the optical fiber core G2 of the present embodiment, the colored resin overflowing from the wire entrance 23a is collected. As a result, even if the colored resin overflows from the coloring die 23, the overflowed colored resin can be recovered and reused.

Incidentally, when the liquid level F3 of the colored resin in the collection tank DT is lower than the level of the liquid level F1 of the colored resin in the coloring die 23, the colored resin inside the upper resin pool 221 can be automatically discharged. Collection of colored resin can be achieved with a simple configuration.

In the manufacturing method of the optical fiber core wire G2 of this embodiment, the temperature of the colored resin inside the coloring die 23 in the standby process is controlled to be lower than the temperature of the colored resin inside the coloring die 23 in the coloring process. In general, colored resins become more viscous as the temperature drops. By controlling the temperature of the colored resin in this embodiment, the viscosity of the colored resin in the waiting process becomes higher than the viscosity of the colored resin in the coloring process. This makes it difficult for the colored resin to overflow from the coloring die 23 even when the resin pressure is positive.

Although the present disclosure has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the disclosure. Also, the number, positions, shapes, etc. of the constituent members described above are not limited to those in the above embodiment, and can be changed to suitable numbers, positions, shapes, etc. in carrying out the present disclosure.

For example, means for applying a positive pressure to the colored resin in the colored die is not limited to the example of the present embodiment. For example, a pump is provided in a supply tank or a supply pipe to feed the liquid to a coloring die, or an inert gas is supplied to the inside of the supply tank to pressurize the inside of the supply tank. A positive pressure can be achieved.

1 manufacturing device 2 die unit 3 ultraviolet irradiation device 21 cover portion 22 receiving portion 23 coloring die 23a inlet port 23b outlet port 24 pressure gauge 25 heater 26 controller DP recovery pipe DT recovery tanks F1, F2, F3 liquid level G1 optical fiber Wire G2 Optical fiber core SP Supply pipe ST Supply tank

Claims (6)

a coloring step of forming a colored layer on the outer periphery of the optical fiber strand by passing the optical fiber strand through a passage port of a coloring die to which a colored resin is supplied from a supply port to produce an optical fiber core;
a waiting step of arranging the coloring dice on a pass line through which the optical fiber is passed in the coloring step in a state where the line speed of the optical fiber is stopped;
In the standby step, the resin pressure of the colored resin in the colored die is a positive pressure,
A method for manufacturing an optical fiber core wire, wherein the coloring step is started while the resin pressure of the colored resin is positive. 2. The optical fiber according to claim 1, wherein a liquid level of said colored resin in a supply tank for supplying said colored resin to said colored dies is higher than a liquid level of said colored resin in said colored dies. manufacturing method. In the standby step, the optical fiber strand is stopped while passing through the passage port.
The method for manufacturing the optical fiber core wire according to claim 1 or 2. The passage port has a wire entry port through which the optical fiber strand enters the coloring die,
In the standby step, attaching a cover portion covering the wire inlet to the coloring dice;
The method for manufacturing the optical fiber core wire according to any one of claims 1 to 3. The passage port has a wire entrance port through which the optical fiber strand enters the coloring die,
recovering the colored resin overflowing from the inlet;
The method for manufacturing the optical fiber core wire according to any one of claims 1 to 4. controlling the temperature of the colored resin inside the coloring die in the standby step so as to be lower than the temperature of the colored resin inside the coloring die in the coloring step;
The method for manufacturing the optical fiber core wire according to any one of claims 1 to 5.

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