JP2017160085A - Method and apparatus for manufacturing optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacturing an optical fiber which can suppress curing of a resin composition in a resin application device, even in manufacture of an optical fiber having special structure.SOLUTION: The method for manufacturing an optical fiber is provided that includes a step of applying a resin composition 25 onto a glass optical fiber 22 from a resin application device 15 while conveying the glass optical fiber 22, and irradiating the glass optical fiber 22 with light in a resin curing device 16 to cure the resin composition 25. The method for manufacturing an optical fiber further includes: a step of starting application of the resin composition 25 onto the glass optical fiber 22 without lighting a light source of the resin curing device 16 prior to a manufacturing step of the optical fiber; and a step of lighting the light source at the stage of reaching the resin composition 25 applied onto the glass optical fiber 22 a space between the resin application device 15 and the resin curing device 16.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical fiber manufacturing method and manufacturing apparatus.

  For example, Patent Documents 1 and 2 describe work procedures at the start of optical fiber manufacturing. As an example, a process of making a bare optical fiber (glass optical fiber) drawn from a heating furnace in which an optical fiber preform is set to a certain extent, and passing a resin coating apparatus and a resin curing apparatus (line passing process), A process of drawing the optical fiber passed through the take-up device (line drawing process), a process of pressurizing and discharging the resin to the resin coating apparatus and starting application to the optical fiber (resin placing process), the outer diameter and tension of the optical fiber The step of increasing the linear speed while adjusting the above conditions (speed increasing step), and the step of winding the product optical fiber around the bobbin when the final conditions are stabilized (product winding step) can be mentioned.

JP 2004-231427 A JP 2000-239039 A

  As a resin composition used as a coating material for an optical fiber, a UV photocurable resin composition that undergoes a crosslinking reaction when irradiated with ultraviolet (UV) light is usually used. Therefore, a UV lamp system is widely adopted as a resin curing device. When manufacturing an optical fiber having a normal structure, the UV lamp located on the lower side of the resin coating device is turned on in advance before the resin composition as a coating material is applied to the bare optical fiber, and then the resin coating is performed. This is a procedure for supplying resin to the apparatus and applying the resin composition to the bare optical fiber.

  However, the present inventor has found that in the production of an optical fiber having a special structure, the frequency of resin clogging or the like in the resin coating apparatus may increase in the steps up to the resin coating described above. Special structures include, for example, a structure in which an element that absorbs UV light and emits light is added to the core or cladding in an optical fiber, a structure in which glass defects are excessively generated, and a scatterer. Examples include existing structures.

  Further, as a result of investigation by the present inventor, when UV light is irradiated from the glass side surface of an optical fiber having a normal structure, the UV light is reflected on the glass surface or almost all of the light is transmitted and is opposite to the glass. The light is emitted from the side surface. This is because the light that can enter the glass does not satisfy the total reflection condition in the glass according to Snell's law, and thus the direction of the light does not change so as to propagate through the optical fiber.

  However, it has been found that in the production of an optical fiber having a special structure, when UV light is irradiated from the glass side surface, spontaneously emitted light or scattered light having no directivity is generated in the bare optical fiber. Since light having no directivity is generated in various directions, a part of the light travels in the longitudinal direction of the optical fiber and propagates in the bare optical fiber. When the resin composition is supplied into the coating apparatus in a state where the light propagating through the bare optical fiber reaches the resin coating apparatus, the resin composition reacts with the light in the resin coating apparatus to be cured. As a result, it is considered that a cured resin is generated in the resin coating apparatus, resulting in poor resin coating or disconnection.

  The present invention has been made in view of the above circumstances, and an optical fiber manufacturing method capable of suppressing curing of a resin composition in a resin coating apparatus even in the manufacture of an optical fiber having a special structure. It is another object of the present invention to provide a manufacturing apparatus.

  In order to solve the above-mentioned problems, the present invention applies a resin composition from a resin coating device to the glass optical fiber while conveying the glass optical fiber, and then irradiates the glass optical fiber with light in a resin curing device. An optical fiber manufacturing method including a step of curing the resin composition, wherein the resin composition is applied to the glass optical fiber without turning on the light source of the resin curing device prior to the optical fiber manufacturing step. And starting the light source of the resin curing device when the resin composition coated on the glass optical fiber reaches between the resin coating device and the resin curing device. An optical fiber manufacturing method is provided.

In the step of turning on the light source, it is preferable that the light source is turned on when the application start end of the resin composition applied onto the glass optical fiber is above the resin curing device.
An outer diameter measuring device is installed between the resin coating device and the resin curing device, the distance from the outer diameter measuring device to the resin curing device is L [m], and the linear velocity of the glass optical fiber is M [ m / min], when the time from when the application start end of the resin composition applied onto the glass optical fiber is detected by the outer diameter measuring instrument until the light source is turned on is t [s], It is preferable to turn on the light source under a condition that satisfies Mt / 60 <L.
It is preferable to have a step of removing the uncured resin composition from the glass optical fiber after the application of the resin composition is started.

  In order to solve the above-mentioned problems, the present invention provides a transporter that transports a glass optical fiber, a resin coating device that applies a resin composition to the glass optical fiber, and the resin composition by irradiating the glass optical fiber with light. A resin curing device having a light source for curing an object, and applying a resin composition to a glass optical fiber without turning on the light source prior to the optical fiber manufacturing process. After the start, the resin coating device or the light source is turned on so that the light source is turned on when the resin composition coated on the glass optical fiber reaches between the resin coating device and the resin curing device. An optical fiber manufacturing apparatus having a control unit for controlling the optical fiber is provided.

An outer diameter measuring device provided between the resin coating device and the resin curing device, and the resin composition coated on the glass optical fiber based on the outer diameter measured by the outer diameter measuring device. It is preferable to include a detection unit that detects a coating start end.
It is preferable that the resin removal part for removing an uncured resin composition from on the said glass optical fiber is installed in at least 1 place of a pass line.

It is preferable that the resin removing portion has a wiping portion for wiping the uncured resin composition on the glass optical fiber.
It is preferable that the resin removing unit includes the wiping unit, a cleaning liquid supply unit, and a resin suction unit.
It is preferable that the resin removing unit has a mechanism for blowing off an uncured resin composition from the glass optical fiber.

  According to the present invention, after the light source is turned on, even if spontaneous emission light or scattered light having no directivity is generated in the glass optical fiber and some of the light propagates in the glass optical fiber, Before the light propagating in the fiber reaches the resin coating device, the propagating light is absorbed by the resin composition coated on the glass optical fiber. Thereby, hardening of the resin composition in a resin coating device can be prevented, and the poor application of a resin and a disconnection can be suppressed.

It is the schematic which shows an example of the manufacturing apparatus of an optical fiber. It is a schematic diagram which shows the example by which propagation light is absorbed by the resin composition. It is a schematic diagram which shows the example which the propagation light reached | attained the resin coating device. It is the schematic which shows an example of the mechanism which detects the application | coating start end of a resin composition. It is a graph which shows an example of the outer diameter fluctuation | variation before and after starting application | coating of a resin composition. It is the schematic which shows an example of the resin removal part. It is the schematic which shows another example of the resin removal part. It is explanatory drawing which shows an example in the case of lighting a light source in order from the bottom to the top in the case of providing two layers of resin coating. It is explanatory drawing which shows an example in the case of lighting a light source in order from the top to the bottom when providing two layers of resin coating.

Hereinafter, based on a preferred embodiment, the present invention will be described with reference to the drawings.
FIG. 1 shows an example of an apparatus for manufacturing a silica glass-based optical fiber. The optical fiber manufacturing apparatus 10 is generally an apparatus that forms a resin coating on a glass optical fiber 22 drawn from an optical fiber preform 21 and winds the obtained optical fiber 24 onto a winding bobbin 20. Therefore, the optical fiber manufacturing apparatus 10 includes a base material holding unit 11, a spinning heating furnace 12, an outer diameter measuring device 13, a cooling device 14, a resin coating device 15, a resin curing device 16, a turn pulley 17, a take-up device 18, and a dancer pulley 19. And a winding bobbin 20 and the like.

  The optical fiber preform 21 is made of quartz glass and is held by the preform holding part 11. At least a part (lower end) of the optical fiber preform 21 is accommodated in the heating furnace 12, and the glass optical fiber 22 is drawn out by heating and melting. The outer diameter measuring device 13 measures the outer diameter of the glass optical fiber 22 drawn out linearly from the heating furnace 12. The cooling device 14 forcibly cools the glass optical fiber 22 and can cool the glass optical fiber 22 to a temperature suitable for resin application in the resin coating device 15 even if the linear velocity of the glass optical fiber 22 is high.

  The resin coating device 15 applies a resin composition (photo-curable resin) serving as a coating layer to the cooled glass optical fiber 22. The resin composition is a liquid resin whose viscosity is adjusted, for example. When the optical fiber 23 coated with the resin composition passes through the resin curing device 16, the resin composition is cured by irradiating the resin composition with UV light from the resin curing device 16 to form a coating layer. The The transport direction of the optical fiber 24 on which the coating layer is formed is changed by the turn pulley 17 located below the heating furnace 12.

  The transport of the optical fiber 24 is performed by a take-up device 18 such as a capstan. That is, the optical fiber manufacturing apparatus 10 includes the take-up device 18 as a transport machine. Since the glass optical fiber 22 being manufactured is continuous from the optical fiber preform 21 to the optical fiber strand 24, the glass light drawn from the optical fiber preform 21 by the conveying force applied to the optical fiber strand 24. A propulsive force that conveys the fiber 22 downward is generated. Between the take-up device 18 and the take-up bobbin 20, a dancer pulley 19 for absorbing slack of the optical fiber 24 and adjusting the winding tension with respect to the take-up bobbin 20 is provided.

  In the process of starting the production of the optical fiber, the optical fiber preform 21 is held by the preform holding part 11 and inserted into the heating furnace 12. The optical fiber preform 21 is heated and melted at a high temperature of about 2000 ° C. in the heating furnace 12, and is drawn downward from the lower portion of the heating furnace 12 while being extended as a glass optical fiber 22 in a high temperature state. A step of passing the resin coating device 15 and the resin curing device 16 through the glass optical fiber 22 (line passing step), a step of applying the passed optical fiber to the take-up device 18 (line drawing step), and supplying resin to the resin coating device 15 Then, the process of starting application to the glass optical fiber 22 (resin placing process), the process of increasing the linear velocity while adjusting the outer diameter and tension conditions of the optical fiber (speed increasing process), and the final conditions The process (winding-up process) of winding up the optical fiber 24 used as a product in the winding bobbin 20 in the stable place is performed.

  In the process of manufacturing an optical fiber as a product, as shown in FIG. 1, the glass optical fiber 22 that is stably drawn out from the optical fiber preform 21 is cooled to a temperature at which the resin composition can be applied. Then, the resin coating device 15 applies a resin composition onto the outer peripheral surface of the glass optical fiber 22, and the resin curing device 16 photocures the resin composition applied on the glass optical fiber 22. A coating layer is formed. The optical fiber 24 on which the coating layer is laminated is taken up at a predetermined speed by the take-up device 18 through the turn pulley 17 and wound around the take-up bobbin 20.

  As shown in FIG. 3, when the resin application by the resin application device 15 is started after the light source of the resin curing device 16 is turned on, spontaneously emitted light or scattered light having no directivity is generated in the glass optical fiber 22. Then, the propagating light 26 reaches the resin coating device 15 from the resin curing device 16, and the resin composition receives the reaction of the propagating light 26 in the resin coating device and reacts to cause curing. As a result, a cured resin is generated in the resin coating device 15, resulting in poor coating or disconnection of the resin.

  Note that spontaneously emitted light or scattered light having no directivity may be generated due to the influence of ultraviolet light irradiated from the side surface in an optical fiber having a special structure in the core or the cladding, for example. Examples of the special structure include a structure in which an element that absorbs UV light and emits light, a structure in which glass defects are excessively generated, and a structure in which scatterers exist.

  In the manufacturing method of the present embodiment, as shown in FIG. 2, the resin composition 25 is supplied to the resin coating device 15 before the light source is turned on to start coating on the glass optical fiber 22. That is, before starting the optical fiber manufacturing process, the application start of the resin composition 25 applied on the glass optical fiber 22 after the application of the resin composition 25 on the glass optical fiber 22 is started without turning on the light source. The light source of the resin curing device 16 is turned on when 25a reaches between the resin coating device 15 and the resin curing device 16. Thereby, since the propagation light 26 in the glass optical fiber 22 is absorbed by the resin composition 25 on the fiber surface, it does not reach the resin coating device 15. Therefore, the resin composition is not cured in the resin coating apparatus 15, and disconnection due to poor resin coating or clogging of the die hole can be suppressed.

  From the viewpoint of easily absorbing the propagation light 26 in the core or the clad, the resin composition 25 having a refractive index higher than that of the clad of the glass optical fiber or having a refractive index comparable to that of the glass optical fiber is preferable.

  When the resin composition applied before the light source (UV lamp) is turned on is transported to the rear of the pass line without being cured, a portion having a member in contact with the optical fiber in the pass line (turn pulley 17, take-up device 18, etc. There is a risk of disconnection. To avoid this, the following measures can be considered.

(1) The fact that the resin composition has been applied to the glass optical fiber is detected by an outer diameter measuring device installed immediately below the resin coating device 15, and the light source is turned on after receiving the detection signal.
(2) A mechanism for physically removing the resin composition before curing is provided in the pass line.

  The application of the resin composition to the glass optical fiber 22 can be detected by installing an outer diameter measuring device 32 between the resin coating device 15 and the resin curing device 16, for example, as shown in FIG. it can. The graph of FIG. 5 shows the elapsed time of the measured value (outer diameter) of the outer diameter measuring instrument 32 from the start of supplying the resin composition to the resin coating device 15 until the resin composition is applied to the glass optical fiber 22. It is a representation.

  At the beginning of application of the resin composition (coating supply unit 41), the measured value of the outer diameter corresponds to the outer diameter D1 of the glass optical fiber 22, but after a while, the measured value of the outer diameter measuring device 32 is steep. There is a timing to increase. This change in the outer diameter means that the application start end 25a of the resin composition has passed the position of the outer diameter measuring device 32. This steep increase in outer diameter (rising portion 42) is detected as the timing when the resin composition starts to be applied, and the light source is turned on so that the uncured resin composition is behind the resin curing device 16 (along the transport direction). Thus, it is possible to prevent the pass line on the side from the resin curing device 16 toward the take-up bobbin 20 from being soiled.

  At this time, the distance from the outer diameter measuring device 32 to the resin curing device 16 is L [m], the linear velocity of the glass optical fiber is M [m / min], and the outer diameter measuring device 32 is applied onto the glass optical fiber 22. When the time from when the application start end 25a of the resin composition is detected to when the light source is turned on is t [s], the light source is preferably turned on under the condition of satisfying Mt / 60 <L. In this case, since the light source can be turned on before the coating start end 25a (see FIG. 2) reaches the resin curing device 16, it is possible to prevent contamination by the uncured resin composition behind the resin curing device 16. it can.

  When the rising portion 42 is detected by the outer diameter measuring device 32, the light source of the resin curing device 16 can be automatically turned on by sending a signal from the detection unit 31 to the power supply device 30 that controls the lighting of the light source. Here, the power supply device 30 is an example of a control unit that controls lighting of the light source.

  In addition, after the rising part 42 is detected by the outer diameter measuring device 32, the outer diameter variation measurement by the outer diameter measuring device 32 is continued, and the outer diameter of the optical fiber 23 coated with the resin composition is unstable. You may make it detect the certain unstable part 43 and the stable part 44 in which the outer diameter of the optical fiber 23 reached the target outer diameter D2. It is preferable to confirm the detection of the stable portion 44 before starting production of the product optical fiber.

  By providing a mechanism (resin removing portion) for removing the uncured resin composition behind the pass line, it is also possible to suppress the stain on the pass line due to the uncured resin. Examples of the configuration for removing the resin composition include wiping and blowing off, but are not limited thereto. Examples of the installation location of the resin removing unit include a space between the resin coating device 15 and the resin curing device 16 and a space between the resin curing device 16 and the turn pulley 17.

  FIG. 6 shows a first configuration example of the resin removing unit. The resin removing unit 50 includes a wiping unit 51 that physically wipes the resin composition 25 on the glass optical fiber 22. The wiping portion 51 is, for example, sponge-like or porous rubber-like. It is preferable that the wiping portion 51 is flexible and deformable so that the wiping portion 51 is in close contact with the outer periphery of the glass optical fiber 22. Further, in order to remove the resin more efficiently in the wiping unit 51, the cleaning unit 51 may include a cleaning liquid supply unit 52 that supplies a cleaning liquid such as alcohol to the wiping unit 51 and a resin suction unit 53 that sucks the wiped resin. desirable. As the resin suction part 53, the structure which sucks the washing | cleaning liquid which melt | dissolved resin with a pump etc. is mentioned.

  FIG. 7 shows a second configuration example of the resin removing unit. The resin removing section 60 blows out gas to the optical fiber 23 in which the resin composition 25 is applied to the casing section 61, and sucks the sprayed resin composition and the intake section 62 for blowing off the resin composition. An intake portion 63 for the purpose. The intake section 62 and the intake section 63 can be arranged in any number and number around the optical fiber 23.

  The present invention can also be applied when two or more resin coatings are provided on a glass optical fiber.

  FIG. 8 shows an embodiment in which the light source is turned on in order from the bottom to the top when providing two layers of resin coating on the glass optical fiber. The first resin coating device 151, the first resin curing device 161, the second resin coating device 152, and the second resin curing device 162 are arranged along the conveyance direction of the glass optical fiber 22. The first resin coating device 151 and the first resin curing device 161 are used for forming the first resin coating. Further, the second resin coating device 152 and the second resin curing device 162 are used for forming a second resin coating.

  First, in FIG. 8A, after the resin application is started from the second resin application device 152, the optical fiber 232 to which the resin composition 252 is applied by the second resin application device 152 is transferred to the second resin curing device 162. Before reaching, the light source of the second resin curing device 162 is turned on. Thereby, since the propagation light 262 generated from the second resin curing device 162 is absorbed by the resin composition 252, the propagation light 262 does not reach the upper second resin coating device 152.

  Thereafter, as shown in FIG. 8B, after starting the application of the resin in the first resin coating device 151, after the optical fiber 231 coated with the resin composition 251 passes through the first resin curing device 161, The light source of the first resin curing device 161 is turned on. Thereby, since propagation light (not shown) generated from the first resin curing device 161 is absorbed by the resin composition 251, the first resin coating device 151 on the upper side and the second resin coating device 152 on the lower side. Even propagation light does not reach.

  FIG. 9 shows an embodiment in which the light source is turned on in order from top to bottom when two layers of resin coating are provided on the glass optical fiber. The arrangement of the first resin coating device 151, the first resin curing device 161, the second resin coating device 152, and the second resin curing device 162 is the same as in FIG.

  First, as shown in FIG. 9A, after the resin application is started in the first resin application device 151, before the optical fiber 231 applied with the resin composition 251 reaches the first resin curing device 161. The light source of the first resin curing device 161 is turned on. Thereby, since the propagation light 261 generated from the first resin curing device 161 is absorbed by the resin composition 251, the propagation light 261 does not reach the upper first resin coating device 151. At this time, since the propagation light 261 can reach the lower second resin coating device 152, the supply of the resin to the second resin coating device 152 is not started, and the second resin coating device 152 is left empty. .

  Thereafter, as shown in FIG. 9B, after the resin composition 251 applied in the first resin coating device 151 reaches the second resin coating device 152, the resin is supplied to the second resin coating device 152. Application to the optical fiber 231 is started. The resin composition 251 applied in the first resin coating device 151 or the resin composition 252 applied in the second resin coating device 152 has reached between the second resin coating device 152 and the second resin curing device 162. Then, before the optical fiber 233 coated with the resin compositions 251 and 252 reaches the second resin curing device 162, the light source of the second resin curing device 162 is turned on. Thereby, since the propagation light 262 generated from the second resin curing device 162 is absorbed by the resin compositions 251 and 252, the propagation light 262 does not reach the upper second resin coating device 152.

  As mentioned above, although this invention has been demonstrated based on suitable embodiment, this invention is not limited to the above-mentioned embodiment, A various change is possible in the range which does not deviate from the summary of this invention.

  In FIG. 4, the configuration in which the timing of the start of coating and the lighting of the light source is adjusted by actually measuring the outer diameter of the optical fiber is shown. However, the timing adjustment is not limited to the example of FIG. It can be carried out. For example, a desired time difference can be realized by setting a predetermined time difference according to the manufacturing conditions and controlling either one or both of the resin coating apparatus and the light source. In an optical fiber manufacturing apparatus, timing adjustment can be automated by providing a control unit that controls the time difference.

DESCRIPTION OF SYMBOLS 10 ... Optical fiber manufacturing apparatus, 15 ... Resin coating apparatus, 16 ... Resin hardening apparatus, 18 ... Take-up apparatus, 20 ... Winding bobbin, 21 ... Optical fiber preform, 22 ... Glass optical fiber, 24 ... Optical fiber strand, 25, 251, 252 ... resin composition, 32 ... outer diameter measuring device, 50, 60 ... resin removing unit, 51 ... wiping unit, 52 ... cleaning liquid supply unit, 53 ... resin suction unit, 151 ... first resin coating device, 152 ... 2nd resin coating device, 161 ... 1st resin curing device, 162 ... 2nd resin curing device.

Claims (10)

Light having a step of curing the resin composition by applying light to the glass optical fiber in a resin curing device after applying the resin composition from the resin coating device to the glass optical fiber while conveying the glass optical fiber A fiber manufacturing method comprising:
Prior to the manufacturing process of the optical fiber, the step of starting the application of the resin composition to the glass optical fiber without turning on the light source of the resin curing device, and the resin composition applied on the glass optical fiber, And a step of turning on the light source of the resin curing device when it reaches between the resin coating device and the resin curing device.   The step of turning on the light source comprises turning on the light source when a coating start end of the resin composition applied onto the glass optical fiber is above the resin curing device. 2. A method for producing an optical fiber according to 1.   An outer diameter measuring device is installed between the resin coating device and the resin curing device, the distance from the outer diameter measuring device to the resin curing device is L [m], and the linear velocity of the glass optical fiber is M [ m / min], when the time from when the application start end of the resin composition applied onto the glass optical fiber is detected by the outer diameter measuring instrument until the light source is turned on is t [s], The method of manufacturing an optical fiber according to claim 1, wherein the light source is turned on under a condition that satisfies Mt / 60 <L.   The optical fiber according to any one of claims 1 to 3, further comprising a step of removing an uncured resin composition from the glass optical fiber after starting application of the resin composition. Production method. A transporter for transporting glass optical fiber;
A resin coating device for coating a resin composition on the glass optical fiber;
A resin curing device having a light source for irradiating the glass optical fiber with light to cure the resin composition;
An optical fiber manufacturing apparatus comprising:
Prior to the manufacturing process of the optical fiber, after starting the application of the resin composition to the glass optical fiber without turning on the light source, the resin composition applied on the glass optical fiber is the resin coating device An apparatus for manufacturing an optical fiber, comprising: a control unit that controls the resin coating device or the light source so that the light source is turned on when reaching the resin curing device.   An outer diameter measuring device provided between the resin coating device and the resin curing device, and the resin composition coated on the glass optical fiber based on the outer diameter measured by the outer diameter measuring device. The optical fiber manufacturing apparatus according to claim 5, further comprising: a detection unit that detects a coating start end.   The optical fiber production according to claim 5 or 6, wherein a resin removing portion for removing the uncured resin composition from the glass optical fiber is installed at at least one place on the pass line. apparatus.   The said resin removal part has a wiping off part which wipes off the uncured resin composition on the said glass optical fiber, The manufacturing apparatus of the optical fiber of Claim 7 characterized by the above-mentioned.   The optical fiber manufacturing apparatus according to claim 8, wherein the resin removing unit includes the wiping unit, a cleaning liquid supply unit, and a resin suction unit.   10. The optical fiber manufacturing apparatus according to claim 7, wherein the resin removing unit has a mechanism for blowing off an uncured resin composition from the glass optical fiber.

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