JP2009294254A - Method and apparatus for producing optical fiber wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an optical fiber wire, where a UV-curable resin coated to the coated optical fiber wire can be irradiated with a desired UV radiant quantities of UV light over the entire length of the optical fiber wire in an atmosphere having a stable oxygen concentration without halting an operating spinning device. <P>SOLUTION: The method for producing an optical fiber wire uses, in an optical fiber spinning step, a UV light irradiation device including a UV transmitting tubular body which is doubly composed of an outer tube and an inner tube, the inner tube being provided with block construction. While the spinning device including the UV light irradiation device operates, the oxygen concentration in the UV transmitting tubular body is stably kept, and by replacing the inner tube of the UV transmitting tubular body every time an optical fiber is spun by a preconfirmed spinning length so as to achieve irradiation with a desired level of UV light, a UV-curable resin can be irradiated with the desired level of UV light over the entire length of the optical fiber. The optical fiber wire excellent in surface curability is thus produced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides an optical fiber strand that can irradiate ultraviolet curable resin coated on an optical fiber strand with a predetermined dose of ultraviolet light in a stable oxygen concentration atmosphere in an optical fiber spinning process. It relates to a manufacturing method.

  The optical fiber made of quartz used for optical communication has a protective coating on its surface for the purpose of preventing strength reduction due to minute scratches and preventing increase in transmission loss due to side pressure. It is common.

  As a material for forming this coating, it is known that an ultraviolet curable resin is usually used in the case of a general-purpose quartz optical fiber used in public communication. As shown in FIG. 8, the quartz optical fiber 1 includes a first layer (primary layer) 2 that is a layer using a relatively soft resin and a second layer (secondary layer) 3 that is a layer that uses a relatively hard resin. In general, a two-layer coat is applied.

  It is known that an optical fiber is manufactured from an optical fiber preform (also called a preform) using a spinning device as shown in FIG. That is, after the preform is melted in the heating furnace 4 and drawn down to a predetermined outer diameter, the preform is cooled by the cooling device 5, the ultraviolet curable resin is applied by the first layer coating device 6, and then the first layer The resin was cured by the ultraviolet irradiation device 7, and the ultraviolet curable resin was similarly applied by the second-layer coating device 8, and then the resin was cured by the second-layer ultraviolet irradiation device 9 and passed through the turn pulley 10. Then, it is wound up as an optical fiber by a winder 11.

  In general, it is known that the curing reaction of an ultraviolet curable resin is a radical polymerization reaction, and oxygen is also known to have a radical scavenging effect. That is, the curing reaction of the ultraviolet curable resin in the presence of oxygen is inhibited. In a strict sense, the degree of curing of the ultraviolet curable resin is different in the interior not in contact with the surface in contact with oxygen or air. Therefore, it is obvious that the oxygen concentration in the atmosphere irradiated with ultraviolet rays needs to be managed in order to ensure the curing characteristics of the surface portion of the optical fiber. In short, to ensure the reliability of the optical fiber, it goes without saying that the entire coating material is sufficiently cured, but it is particularly important to ensure the degree of curing of the surface portion in contact with oxygen or air. It is.

  As described in Patent Document 1, generally, an ultraviolet lamp and a quartz tube (also referred to as an ultraviolet transmissive cylindrical body or a cylindrical transparent body) are installed in an ultraviolet irradiation device, and oxygen inside the quartz tube is provided. The concentration is controlled to be low, for example, several hundred ppm or less and several% or less. And when an optical fiber passes the inside of the said quartz tube, the light quantity from an ultraviolet lamp is irradiated through an ultraviolet transmissive cylindrical body.

  Generally, the curing reaction of an ultraviolet curable resin is an exothermic reaction, and it is known that there are components that volatilize during the curing reaction centering on low molecular weight components. This component must be efficiently discharged from the UV transmitting cylinder. If it remains in the ultraviolet transmissive cylindrical body without being discharged, it will adhere to the inner wall of the ultraviolet transmissive cylindrical body, and the irradiation of the light quantity from the ultraviolet lamp will be hindered. As a result, the amount of light that should be irradiated to the UV curable resin decreases, making it difficult to have a sufficient degree of curing as a coating material for the optical fiber, resulting in a loss of reliability as an optical fiber. To do.

  Several techniques have been proposed as a technique for solving the above-described problems. Patent Document 1 describes a technique for defining the oxygen concentration in an ultraviolet transmitting cylindrical body. Japanese Patent Application Laid-Open No. H10-228561 describes a method of defining the oxygen concentration by applying TiO2 (also referred to as titanium dioxide) to an ultraviolet transmitting cylindrical body. Patent Document 3 describes a method in which a plurality of ultraviolet irradiation devices are arranged and at least one lamp has a low oxygen concentration and the other has a high oxygen concentration.

  However, all of the techniques of the above-described patent documents only manage the oxygen concentration, the amount of ultraviolet light, etc. in the ultraviolet transmitting cylindrical body, and do not clearly indicate the method associated with the most important surface hardening state. . Patent Document 3 clearly discloses infrared spectrum analysis, but it is known that the minimum value of the aperture at the aperture is about 10 μm due to the limitation of the measurement wavelength of the infrared spectroscopy technique. If the aperture is reduced too much, it will deviate from the calibration curve, resulting in poor reproducibility, and the quantitativeness cannot be clearly indicated. Therefore, in principle, it is impossible for the infrared spectroscopy method to quantitatively grasp the cured state of only the surface, for example, the cured state of 1 μm on the surface layer.

  In Patent Document 1, the oxygen concentration in the quartz tube is defined as 500 ppm to 5%, but is defined only so as not to lower the ultraviolet transmittance of the quartz tube. No mention of sex. That is, it is a technique that can be applied only to the specific ultraviolet curable resin that is the subject of the embodiment, and is not applicable to a wide variety of ultraviolet curable resins.

In Patent Document 2, it is expensive to apply TiO ₂ itself. Moreover, there exists a problem that an ultraviolet permeable cylindrical body will become dirty depending on the resin seed | species from which a volatile component differs. Furthermore, it is known that TiO ₂ itself has absorption in the ultraviolet region, and there is a problem that the amount of light applied to the ultraviolet curable resin that should be irradiated is reduced.

In Patent Document 3, it is known that the volatile components once attached to the ultraviolet transmitting cylindrical body are not removed even when the oxygen concentration is increased, and there is a problem that the amount of light applied to the ultraviolet curable resin is reduced. Furthermore, there is a problem that the degree of curing of the surface is lowered because radicals are not generated again even if the surface layer once supplemented with oxygen is irradiated with ultraviolet rays.
JP 2003-095704 A JP 2000-005694 A Japanese Patent Laid-Open No. 11-347479

The present invention provides a method for manufacturing an optical fiber having excellent surface properties over the entire length by stably maintaining the oxygen concentration in the cylinder without performing any special surface treatment on the ultraviolet transmitting cylindrical body. This is the primary purpose.
Moreover, this invention makes it the 2nd objective to provide the manufacturing apparatus of the optical fiber strand provided with the surface property which was excellent over the full length.

  In the method of manufacturing an optical fiber according to claim 1 of the present invention, a silica-based optical fiber formed by applying an ultraviolet curable resin passes through an ultraviolet transmitting cylindrical body installed in an ultraviolet irradiation device. A process of manufacturing an optical fiber having a configuration in which ultraviolet rays are irradiated when the outer tube and the inner tube are overlapped as the ultraviolet transmitting cylindrical body (hereinafter also referred to as duplexing), and the inner Using a tube having a divided structure, the oxygen concentration in the ultraviolet transmitting cylindrical body is kept stable, and the resin is irradiated with ultraviolet rays having a desired ultraviolet ray amount over the entire length of the optical fiber. The inner tube is exchanged for each spinning length confirmed in advance.

  The method for manufacturing an optical fiber according to claim 2 of the present invention is characterized in that, in claim 1, a structure that is halved along the traveling direction of the optical fiber is used as the split structure. To do.

  According to a third aspect of the present invention, there is provided a method of manufacturing an optical fiber according to the second aspect of the present invention, wherein the inner tube and a holding jig for the inner tube are connected to a lifting device by supporting means. A first step in which the inner tube is moved from the steady position to the lower side of the ultraviolet irradiation device until the entire inner tube is exposed, and then is divided and removed from the gripping jig using the half structure of the inner tube; and a new inner tube And a second step of returning a new inner tube to a steady position of the inner tube using the lifting device after the device is installed on the gripping jig.

  The method for manufacturing an optical fiber according to claim 4 of the present invention uses an optical fiber manufactured by the manufacturing method according to claim 3 and provides a ring shape so as to have one intersection. When the tensile test is performed using a tensile tester, the average value of the load measured by the tension pickup is optically measured. Calculated as the surface friction force of the contact portion between the fiber strands, and the degree of contamination and replacement frequency of the inner tube of the UV transmitting cylindrical body depending on the spinning length so that the calculated surface friction force is smaller than the desired value And a replacement step of the inner pipe is performed based on the relationship.

  An optical fiber according to a fifth aspect of the present invention is manufactured by the manufacturing method according to any one of the first to fourth aspects.

  According to a sixth aspect of the present invention, there is provided a method for measuring a surface friction force of an optical fiber, wherein the optical fiber is formed by using the optical fiber of the fifth aspect and having a ring shape so as to have one intersection. The strands are configured so as to twist twice in a spiral at the intersection, and the average value of the load measured by the tension pickup when performing a tensile test using a tensile tester is determined between the optical fiber strands. It is calculated as the frictional force of the contact portion.

  According to a seventh aspect of the present invention, there is provided an optical fiber manufacturing apparatus according to the fifth aspect of the present invention, wherein in the present invention, the outer tube and the inner tube are stacked (doubled) as the ultraviolet transmitting cylindrical body, In addition, at least a configuration in which the inner tube having a divided structure is used and the inner tube and a gripping jig for the inner tube are connected to a lifting device by a support means is provided.

According to the method of manufacturing an optical fiber of the present invention, when a silica-based optical fiber formed by applying an ultraviolet curable resin passes through an ultraviolet transmission cylindrical body installed in an ultraviolet irradiation device, ultraviolet rays are emitted. It is configured to irradiate, and as the ultraviolet transmitting cylindrical body, an outer tube and an inner tube are arranged so as to overlap (hereinafter also referred to as duplex), and the inner tube has a divided structure, and the ultraviolet transmitting cylindrical shape is used. Replacing the inner tube for each spinning length confirmed in advance so that the oxygen concentration in the body is kept stable and the resin is irradiated with ultraviolet rays having a desired ultraviolet ray amount over the entire length of the optical fiber. It is characterized by. Therefore, when used for a long time, the volatile component of the ultraviolet curable resin adheres to the inner wall of the inner tube, causing dirt and the like. It is possible to avoid a troubled situation in which the amount of ultraviolet rays cannot reach in advance. By stably maintaining the oxygen concentration in the cylinder, it is possible to produce an optical fiber having excellent surface properties over the entire length.
An apparatus for manufacturing an optical fiber according to the present invention includes an ultraviolet transmissive cylindrical body in which an outer tube and an inner tube are overlapped (doubled) and the inner tube is divided, and the inner tube and the inner tube. The gripping jig includes at least a configuration in which the holding jig is connected to the lifting device by a support means. Therefore, it is possible to appropriately replace the inner tube according to the degree of dirt on the inner wall of the inner tube. Therefore, the present invention provides an apparatus for manufacturing an optical fiber, which is capable of performing an ultraviolet curing treatment on a coating resin for the optical fiber at all times under stable conditions.

  In order to achieve the above object, in the manufacturing method of the present invention, when the ultraviolet transmitting cylindrical body 14 is soiled to a predetermined degree depending on the spinning length, the oxygen concentration in the cylinder is not changed. It uses a technique that allows it to be exchanged.

  Specifically, in the method of manufacturing an optical fiber according to the present invention, in the step of spinning an optical fiber made of quartz glass, a cylindrical transparent body installed in the ultraviolet irradiation device (7 or 9) is doubled. And the inner tube 14 has a divided structure. A jig 17 for holding the inner pipe 14 from below and a device 15 for raising and lowering the jig 17 are installed, and the inner pipe 14 and the jig 17 are moved below the ultraviolet irradiation device (7 or 9) during spinning, The inner tube 14 having a divided structure is removed and replaced with another inner tube 14 and moved upward together with a jig 17 that holds the inner tube 14, whereby the inner tube 14 can be replaced during spinning.

  During the replacement operation, the space through which the optical fiber passes is enclosed by the outer tube 13 of the cylindrical transparent body, and the oxygen concentration is controlled by the purge gas as in the normal state. As a result, the optical fiber 12 having excellent surface properties can be continuously manufactured. The exchange timing is carried out for each designated spinning length by examining in advance the degree of contamination of the cylindrical transparent body 14 depending on the spinning length.

  In the above configuration, the inner tube 14 and the outer tube 13 of the cylindrical transparent body need not only be transparent to allow ultraviolet rays to pass through, but also have a high internal temperature when the ultraviolet irradiation device is turned on. Therefore, it is preferable that the material is made of quartz having transparency and heat resistance. Natural quartz may be used, but synthetic quartz is usually used, and first grade hard glass (also referred to as Pyrex (registered trademark) glass) or inexpensive second grade hard glass is used. Although it is expensive, pure quartz may be used. Moreover, as long as it has the permeability | transmittance and heat resistance with respect to an ultraviolet-ray, it can apply also with the material made from a ceramic, and it does not restrict | limit in particular.

  Although the dimensions of the inner tube 14 and the outer tube 13 of the columnar transparent body are not particularly specified, for example, those having an outer diameter of 6 to 30 mm and a wall thickness of 0.5 to 2.0 mm can be used. The length can be appropriately used according to the length of the ultraviolet lamp or the lamp.

  Further, in the above configuration, the division structure of the infectious disease can be not only a longitudinally divided half (1/2 divided) structure but also an arbitrary divided structure such as a 1/3 divided or a 1/4 divided. In addition, a structure using a horizontal division structure, a jig, or the like may be combined.

  Further, the joints of the divided inner pipes may be simple plane alignment, but may be stepped or tapered. According to such a configuration, handling can be easily performed at the time of exchanging the inner tube 14 during spinning.

  In the above-described configuration, the jig 17 that holds the inner tube 14 does not need transparency and needs to be strong enough to support the inner tube 14, and needs to be processed to provide a location for connecting the purge gas supply tube 25. It is preferably made of metal. Although the material is not particularly specified, for example, iron, stainless steel, aluminum, titanium, brass, copper, or the like can be used.

  The shape and dimensions of the jig 17 may be appropriately set according to the shape and structure of the inner tube 14 and the ultraviolet irradiation device (7 or 9), and are not particularly limited. The same applies to the shape and dimensions of the purge gas supply pipe 25, and there is no particular limitation.

  The technique of the present invention is an effective technique for all oxygen concentrations. In other words, since this is a method for manufacturing an optical fiber having a good surface property, it is not a method for strictly controlling the oxygen concentration as in the prior art. And it is a technique applicable to various ultraviolet curable resins. Further, even in the case of long drawing using a large preform, there is no limitation on the spinning length, and there is no limitation on process conditions such as spinning line speed.

The method of the present invention does not require a special treatment such as coating TiO ₂ on the quartz tube, and can always maintain a certain amount of ultraviolet transmission. Further, since TiO ₂ itself does not absorb ultraviolet rays, it is possible to efficiently irradiate the ultraviolet curable resin.

  The technique of the present invention is a technique for exchanging a dirty quartz tube after a certain amount of use, and can be applied to any ultraviolet curable resin in principle. It is possible to ensure a certain level of surface curability in the longitudinal direction of the optical fiber.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a cylindrical transparent body of the present invention. The columnar transparent body of the present invention is duplexed with the inner tube 14 and the outer tube 13, and further has a structure in which the inner tube 14 can be divided. In a steady state where the spinning device is operating, the optical fiber 12 runs inside the inner tube 14.

  FIG. 2 is a schematic diagram showing the positional relationship of the ultraviolet irradiation device (7 or 9) and the cylindrical transparent body 14 during spinning. FIG. 3 is a schematic view when the inner tube 14 is exchanged during spinning. The inner tube 14 is installed on an upper portion of a jig 17 that holds the inner tube 14, and the jig 17 is connected to a device 15 having an elevating mechanism via an arm 16 that is a support device. In a steady state during spinning, the inner tube 14 is disposed inside the outer tube 13.

  At the time of replacement during spinning, the jig 16 and the inner tube 14 are moved downward by moving the arm 16 downward, the inner tube 14 having a divided structure is removed, and another inner tube 14 (with UV transmissivity ensured) is removed. Replace with. After the replacement, the jig 16 and the inner tube 14 are moved to the ultraviolet irradiation device (7 or 9) by raising the arm 16 upward, and return to the steady position.

  FIG. 4 shows the configuration of the upper part of the ultraviolet irradiation device (7 or 9) and the vicinity of the gripping part of the cylindrical transparent body 13. The purge gas passing through the cylindrical transparent body 13 is exhausted. That is, a member 19 that holds the outer tube 13 is attached to a fixed object called the exhaust jig 18, and the outer tube 13 is held by this member 19.

  An exhaust pipe 20 is connected to the exhaust jig 18 so as to exhaust purge gas and volatile components of the ultraviolet curable resin. Further, an oxygen sensor 21 for measuring the oxygen concentration in the exhaust jig 18 or the upper part of the cylindrical transparent body (13 or 14) is attached. In addition, a member referred to as an iris 22 is installed on the upper part of the exhaust jig 18 to improve the sealing property of the upper part. Generally, the inner diameter of the iris 22 is about φ5 mm.

  The configuration clearly shown in FIG. 4 clearly shows an example of the present invention, and does not particularly limit the structure, dimensions, materials, and the like. Further, an additional facility such as a flow rate adjustment mechanism for exhausting and a temperature monitor may be added, or constituent members such as the oxygen sensor 21 may be omitted or simplified.

  FIG. 5 shows the configuration of the lower part of the ultraviolet irradiation device (7 or 9) and the vicinity of the holding part of the cylindrical transparent body (13 or 14). The purge gas that passes through the cylindrical transparent body 14 is allowed to flow. That is, a member 24 that holds the outer tube 13 is attached to a fixed object called the purge gas jig 23, and the outer tube 13 is held by this member 24.

  A purge gas supply pipe 25 is connected to the purge gas jig 23 so that the purge gas can be introduced. Further, a jig 17 that holds the inner pipe 14 is housed in the lower portion of the purge gas jig 23, and the inner pipe 14 is removed by the clearance between the inner wall of the purge gas jig 23 and the outer wall of the jig 17 that holds the inner pipe 14. The jig 17 and the inner tube 14 to be gripped are positioned.

  The configuration clearly shown in FIG. 5 clearly shows an example of the present invention, and does not particularly limit the structure, dimensions, materials, and the like. Further, a mechanism for adjusting the flow rate and pressure of the purge gas may be attached. Furthermore, a jig 17 that holds the inner tube 14 and another method for positioning the inner tube 14 may be used.

  In general, in order to obtain a desired oxygen concentration in a predetermined space, oxygen or a gas containing oxygen at a certain ratio, for example, a gas that does not chemically react with oxygen with respect to air, for example, inert gas such as nitrogen, helium, or argon It is known that this is achieved by forming a gas having a desired oxygen concentration by mixing the gas at a certain ratio and occupying a predetermined space with the gas.

  The gas is applied to the present invention as a purge gas, and is flowed from the purge gas supply pipe 25 through the purge gas jig 23 to the cylindrical transparent body 14 and exhausted through the exhaust jig 18 to the exhaust pipe 20 so that the outside of the cylindrical transparent body is removed. It becomes possible to manage the internal space of the tube 13 at a constant oxygen concentration. The specified configuration clearly shows the case of the present invention, and does not particularly limit the type, flow rate, mixing ratio, temperature, and the like of the gas.

  Examples will be described in detail below. In this example, an optical fiber strand 12 having a strand diameter of φ250 μm is formed using the same material, that is, a single mode optical fiber preform and an ultraviolet curable resin (Desolite series) manufactured by JSR, and is cylindrically transparent. The degree of contamination of the body 14 and the surface curability of the optical fiber 12 are evaluated. As the ultraviolet irradiation device, model number manufactured by Oak Co .; HMW-523BLCM (ultraviolet lamp length: 500 mm, output: 6 kW) was used.

  The degree of contamination of the columnar transparent body 14 (also referred to as an ultraviolet transmissive cylindrical body) was measured using a model number manufactured by Oak Co .; UV-M02 as an ultraviolet illuminometer. The ultraviolet transmitting cylindrical body 14 was in a cylindrical state that was not divided, and the amount of ultraviolet rays that passed through the ultraviolet transmitting cylindrical body 14 by irradiating ultraviolet rays was measured with an illuminometer. The illuminance was measured before and after use in spinning an optical fiber, and the ratio was used as a percentage of ultraviolet transmission.

  The surface curability of the optical fiber 12 was measured as shown in the measurement schematic diagram of FIG. First, a ring 26 having a diameter of 7 cm is formed from an optical fiber strand (about 50 cm) of the sample, and a spirally twisted two-turn twist is formed at a crossing portion 27. Next, a sample was set in a commercially available vertical tensile tester, pulled at a tensile speed of 5 mm per minute for 2 minutes, and a load measured by a tension pickup was measured, and an average value for 2 minutes was calculated. That is, since it corresponds to the measurement of the frictional force (referred to as surface frictional force) at the contact portion between the optical fiber strands 12, the average load value is considered to be an index of surface curability.

  Usually, it can be determined that the smaller the surface friction force, the better the surface property, that is, the better the surface curability. Conversely, as the surface friction force is larger, the surface of the optical fiber 12 is more sticky, and it can be determined that the surface property is not excellent (the surface curability is not excellent). The average value of the number of test N = 10 was used for the data.

  Table 1 shows the evaluation test results of Example 1. The optical fiber 12 is made with the ultraviolet transmitting cylindrical body 14 having a different degree of contamination, and the surface friction force is measured by the method shown in FIG. From this result, it is conceived that the surface curability of the optical fiber 12 is ensured if the amount of transmitted ultraviolet light is 60% or more. From the result of Example 1, in the case of this sample, if the surface friction force was 0.2 N (Newton) or less, it was determined to be acceptable.

  Table 2 shows the evaluation test results of Example 2. This is a measurement of the degree of soiling of the UV-transmitting cylindrical body every 20 km in terms of spinning length. From this result, if the inner tube 14 of the ultraviolet ray transmitting cylindrical body is replaced every 40 km in the spinning length, the ultraviolet ray transmission amount is always 60% or more, and the surface frictional force is always 0.2 N or less. It is conceivable that an optical fiber strand 12 can be obtained.

  Table 3 shows the evaluation test results of Example 3. The inner tube 14 of the ultraviolet transmitting cylindrical body is replaced every 40 km in spinning length, and the spinning is continuously performed for 360 km. After the spinning, the surface frictional force was measured using a sample obtained by winding up the optical fiber 12 and winding the optical fiber 12 after the spinning. As a result, it was confirmed that the amount of transmitted ultraviolet light was 60% or more over the entire length, and the surface friction force was 0.2 N or less over the entire length. That is, the optical fiber 12 excellent in surface curability could be obtained over the entire length (spinning full length) of the prepared sample.

  FIG. 7 is a graph of the evaluation test results of Example 3.

  In this embodiment, it is theoretically possible to perform further long drawing continuously. For example, it is possible to obtain the optical fiber 12 having excellent surface curability even when the spinning length is 1000 km or more.

  In the case of the ultraviolet curable resin used in this example, the criterion for determining the surface frictional force is 0.2 N, but there is no particular limitation on providing other criteria. Similarly, although the criterion for determining the amount of transmitted ultraviolet light is 60%, there is no particular limitation on the provision of other criteria.

Schematic which shows the structure of a cylindrical transparent body. Schematic which shows the positional relationship at the time of spinning spinning of an ultraviolet irradiation device or a cylindrical transparent body. The schematic of the apparatus which replaces | exchanges the cylindrical transparent body of an inner tube | pipe during spinning. The figure which shows the structure of the upper part of an ultraviolet irradiation device, and the holding part vicinity of a cylindrical transparent body. The figure which shows the structure of the holding part vicinity of the lower part of an ultraviolet irradiation device, and a cylindrical transparent body. The figure which shows the measuring point of the surface frictional force of an optical fiber strand. The graph of the evaluation test result of Example 3. The structure schematic of an optical fiber strand. Schematic of an optical fiber spinning apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Quartz optical fiber, 1st layer (primary layer), 3rd layer (secondary layer), 4 heating furnace, 5 cooling device, 6 1st layer coating device, 7 1st layer ultraviolet irradiation device, 8 2 Coating device for layer 9, UV irradiation device for second layer, 10 turn pulley, 11 winder, 12 optical fiber, 13 outer tube of cylindrical transparent body, 14 inner tube of cylindrical transparent body, 15 lift Equipment, 16 Arm, 17 Inner pipe gripping jig, 18 Exhaust jig, 19 Outer pipe gripping member, 20 Exhaust pipe, 21 Oxygen sensor, 22 Iris, 23 Purge gas jig, 24 Outer pipe gripping member, 25 For supplying purge gas Tube, 26 rings, 27 intersections.

Claims (7)

  Manufacture of optical fiber with a structure in which UV light is irradiated when a silica-based optical fiber coated with UV-curable resin passes through a UV transmitting cylindrical body installed in the UV irradiation device In the process, the outer tube and the inner tube are arranged as the ultraviolet transmitting cylindrical body and the inner tube is divided, and the oxygen concentration in the ultraviolet transmitting cylindrical body is kept stable. The inner tube is exchanged for each spinning length confirmed in advance so that the resin is irradiated with ultraviolet rays having a desired ultraviolet ray amount over the entire length of the optical fiber. Production method.   The method for manufacturing an optical fiber according to claim 1, wherein a structure that is halved along the traveling direction of the optical fiber is used as the split structure.   After moving the inner tube from the steady position to the lower part of the ultraviolet irradiation device until the entire inner tube is exposed, using a configuration in which the inner tube and a holding jig for the inner tube are connected to a lifting device by a supporting means. A first step of dividing and removing from the gripping jig using the half structure of the inner pipe, and a new inner pipe is installed in the gripping jig and then moved to a steady position of the inner pipe using the lifting device. The method for manufacturing an optical fiber according to claim 2, further comprising a replacement step of the inner tube including a second step of returning a new inner tube.   Using the optical fiber manufactured by the manufacturing method according to claim 3, an optical fiber having a ring shape so as to have one intersecting portion is rotated twice in a spiral shape at the intersecting portion. When the tensile test is performed using a tensile tester, the average value of the load measured by the tension pickup is calculated as the surface friction force of the contact portion between the optical fiber strands. The relationship between the degree of contamination of the inner tube of the ultraviolet transmitting cylindrical body and the replacement frequency depending on the spinning length is determined in advance so that the surface friction force is smaller than the desired value, and based on the relationship, the inner tube A method of manufacturing an optical fiber, wherein an exchange process is performed.   An optical fiber strand produced by the manufacturing method according to claim 1.   6. The optical fiber strand according to claim 5, wherein the optical fiber strand having a ring shape so as to have one intersecting portion has a structure in which a twist of two rotations is spirally formed at the intersecting portion, The surface frictional force of the optical fiber is characterized by calculating the average value of the load measured by the tension pickup when performing a tensile test using a testing machine as the frictional force of the contact portion between the optical fiber Measuring method.   An ultraviolet transmission cylindrical body in which the outer tube and the inner tube are overlapped and the inner tube is divided, and a structure in which the inner tube and a holding jig for the inner tube are connected to a lifting device by a support means. An apparatus for manufacturing an optical fiber, comprising: at least an optical fiber.

Images