Method for manufacturing optical fibers and apparatus for manufacturing optical fibers

Abstract

To provide a method of manufacturing an optical fiber which suppresses variation of a coating thickness deviation of an optical fiber, etc.SOLUTION: A method of manufacturing an optical fiber includes the steps of: melting an optical fiber base material and wiredrawing an optical fiber bare wire; coating the optical fiber bare wire with a resin by a coating device to form an optical fiber element wire; and changing a direction of the optical fiber bare wire by a direct down roller and winding the optical fiber bare wire by a winding device. The direct down roller is a non-rotary guide roller.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing an optical fiber and an apparatus for manufacturing an optical fiber.

Background Art

[0002] Patent Document 1 discloses a method for manufacturing an optical fiber. In this method for manufacturing an optical fiber, a resin is coated on an optical fiber bare wire obtained by melting and drawing an optical fiber preform. Then, the optical fiber element wire coated with the resin is redirected by a directly-below roller and wound by a winding device. Thereby, an optical fiber is manufactured. Patent Document 2 discloses that the direction of an optical fiber bare wire is changed by an air guide at any position from a spinning process to a coating process. Patent Document 3 discloses that when the coating of a thermosetting resin comes into contact with a directly-below roller while being uncured, it is deformed, so a fluid is blown out from a guide portion of the directly-below roller to float it up.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In conventional optical fiber manufacturing methods, minute vibrations (vertical vibrations) can occur in the roller directly below which the optical fiber strands are reoriented, due to a misalignment between the rotation axis and the perpendicularity of the roller. These minute vibrations propagate to the optical fiber strands and the connected bare optical fiber wires guided by the roller directly below, causing the bare optical fiber wires to vibrate. When the bare optical fiber wires vibrate, the bare optical fiber wires, which are coated with resin, may deviate slightly horizontally from their predetermined path, causing uneven thickness in the resin coating of the optical fiber strands or fluctuations in the outer diameter. Furthermore, these fluctuations may also affect the quality characteristics of the optical fiber. In addition, with conventional rollers, the rotational resistance of the bearing is added to the wire tension, and since there are individual differences in the rotational resistance of the bearings, it may not be possible to adjust the wire tension to a satisfactory range. Moreover, in the manufacturing method of multicore optical fibers, which have multiple cores in a single optical fiber, vertical vibrations of the roller directly below can cause the optical fiber to roll at the bottom of the groove of the roller directly below, twisting in the longitudinal direction. When multicore optical fibers become twisted, it becomes difficult to align the multiple cores in the correct order and position when connecting them to each other. Therefore, there is a need for a manufacturing method and apparatus for optical fibers that can suppress variations such as the effect on wire tension and uneven thickness of the optical fiber coating.

[0005] The purpose of this disclosure is to provide a method for manufacturing optical fibers and an apparatus for manufacturing optical fibers that can suppress variations such as uneven coating thickness of optical fibers. [Means for solving the problem]

[0006] This disclosure provides a method for manufacturing optical fibers. This method for manufacturing optical fibers comprises the steps of: melting an optical fiber matrix to draw a bare optical fiber; coating the bare optical fiber with a resin using a coating device to form optical fiber strands; and changing the direction of the optical fiber strands with a roller directly below and winding the optical fiber strands with a winding device. The roller directly below is a non-rotating guide roller.

[0007] This disclosure provides an apparatus for manufacturing optical fibers. This apparatus comprises a melting device, a coating device, a winding device, and a direct roller. The melting device melts the optical fiber base material to draw bare optical fiber wires from it. The coating device coats the bare optical fiber wires with resin to form optical fiber strands. The winding device winds up the optical fiber strands. The direct roller is located between the coating device and the winding device in the path of the optical fiber strands and changes the direction of the optical fiber strands. The direct roller is a non-rotating guide roller. [Effects of the Invention]

[0008] According to this disclosure, variations in the thickness of the optical fiber coating can be suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of an optical fiber manufacturing apparatus according to one embodiment. [Figure 2] Figure 2 is a perspective view showing a non-contact guide. [Figure 3] Figure 3 is an exploded perspective view of the non-contact guide shown in Figure 2, disassembled along the central axis C. [Figure 4] Figure 4 is a cross-sectional view of the non-contact guide shown in Figure 2, cut along the IV-IV line. [Figure 5] Figure 5 is an exploded perspective view of the internal components of the non-contact guide shown in Figure 2, disassembled along the central axis C. [Figure 6] Figure 6 is a magnified view of area A, enclosed by the dashed line, of the non-contact guide shown in Figure 4. [Figure 7] Figure 7 is a cross-sectional view of the non-contact guide shown in Figure 2, cut along the line VII-VII. [Modes for carrying out the invention]

[0010] [Description of Embodiments in this Disclosure] First, the contents of the embodiments of this disclosure will be listed and explained. One embodiment of a method for manufacturing an optical fiber comprises the steps of: melting an optical fiber base material to draw a bare optical fiber wire; coating the bare optical fiber wire with a coating device to form an optical fiber strand; and changing the direction of the optical fiber strand with a roller directly below and winding the optical fiber strand with a winding device. The roller directly below is a non-rotating guide roller.

[0011] An optical fiber manufacturing apparatus according to one embodiment comprises a melting apparatus, a coating apparatus, a winding apparatus, and a direct roller. The melting apparatus melts the optical fiber base material to draw bare optical fiber wires from it. The coating apparatus coats the bare optical fiber wires with resin to form optical fiber strands. The winding apparatus winds up the optical fiber strands. The direct roller is located between the coating apparatus and the winding apparatus in the path of the optical fiber strands and changes the direction of the optical fiber strands. The direct roller is a non-rotating guide roller.

[0012] In the optical fiber manufacturing method and apparatus according to the above embodiment, when winding up resin-coated optical fiber strands, the direction of the optical fiber strands is changed by a roller directly below them. This roller directly below is a non-rotating guide roller and transports the optical fiber strands without rotating. In this case, since the roller directly below does not rotate, vibrations from the roller directly below are not transmitted to the bare optical fiber, etc. Therefore, according to the above embodiment, it is possible to manufacture optical fibers in which the resin coating of the bare optical fiber is properly performed and variations such as uneven coating thickness are suppressed.

[0013] In one embodiment, in the above-described method or apparatus for manufacturing optical fibers, the non-rotating guide roller is a non-contact guide having a guide portion along its outer surface on which a portion of the optical fiber strand can be wound, and the guide portion of the non-contact guide may be provided with a plurality of nozzles for blowing out gas to suspend the optical fiber strand. According to this embodiment, the optical fiber strand is suspended by gas, that is, the optical fiber strand is transported in a non-contact state. In this case, the non-contact guide allows the resin-coated optical fiber strand to be changed in direction without contacting the roller, so vibrations from the non-contact guide are not transmitted to the bare optical fiber, etc. Furthermore, vibrations from various devices downstream of the non-contact guide (e.g., winding device, etc.) are also attenuated by the gas suspension of the non-contact guide and are less likely to be transmitted to the bare optical fiber, etc. As a result, according to this embodiment, it is possible to manufacture optical fibers in which the resin coating of the bare optical fiber is properly performed and variations such as uneven coating thickness are further suppressed.

[0014] In one embodiment, in the above-described method or apparatus for manufacturing optical fibers, the guide portion of the non-contact guide may be provided with a gap that communicates with the nozzle and extends along the outer surface, and the width of the gap may be adjustable. In this case, the stability of the floating of the optical fiber strands in the non-contact guide, which is responsible for changing the direction of the optical fiber strands, can be easily controlled by adjusting the width of the gap. Therefore, according to this embodiment, it is possible to manufacture optical fibers with suppressed coating thickness variation over a long period of time.

[0015] In one embodiment, the above-described method or apparatus for manufacturing optical fibers may further include a step or measuring apparatus for measuring the wire tension. In this case, the winding step or control device may adjust the gap width of the non-contact guide based on the measured wire tension and wind the optical fiber strands through the non-contact guide. In this case, by blowing gas at a blowing pressure corresponding to the wire tension, the optical fiber strands can be guided by the non-contact guide while maintaining an appropriate amount of suspended space. Therefore, according to this embodiment, it is possible to manufacture optical fibers that further suppress variations such as uneven coating thickness.

[0016] As one embodiment, the above-described method or apparatus for manufacturing an optical fiber may further include a step or a measuring device for measuring the fiber diameter of the optical fiber preform. In this case, in the winding step or the control device, the width of the gap of the non-contact guide may be adjusted based on the measured fiber diameter, and the optical fiber preform may be wound through the non-contact guide. In this case, by setting the width of the gap according to the fiber diameter of the optical fiber preform, the optical fiber preform can be guided by the non-contact guide while maintaining an appropriate floating amount. Therefore, according to this embodiment, an optical fiber with further suppressed variations such as coating eccentricity can be manufactured.

[0017] As one embodiment, in the above-described method or apparatus for manufacturing an optical fiber, the non-contact guide may include an internal member having a plurality of ejection ports on its outer peripheral surface, and a first flange and a second flange that accommodate the internal member so as to sandwich it in a first direction intersecting the ejection direction of the gas ejected from the plurality of ejection ports. At least one of the first flange and the second flange may be attached to the internal member such that a gap through which the gas ejected from the plurality of ejection ports passes is provided between the outer edge of the first flange and the outer edge of the second flange. At least one of the first flange and the second flange may be movable in a direction in which the width of the gap changes. In this case, the stability of the floating of the optical fiber preform by the non-contact guide can be easily adjusted with a simple configuration. Therefore, according to this embodiment, an optical fiber can be manufactured by easily suppressing coating eccentricity. In this embodiment, at least one of the first flange and the second flange may be moved to adjust the width of the gap.

[0018] [Details of Embodiments of the Present Disclosure] A specific example of a method for manufacturing an optical fiber and a manufacturing apparatus for an optical fiber according to an embodiment of the present disclosure will be described below with reference to the drawings. In the following description, the same reference numerals will be used for the same elements or elements having the same function, and duplicate descriptions will be omitted. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0019] Referring to FIG. 1, a method for manufacturing an optical fiber and a manufacturing apparatus for an optical fiber according to an embodiment will be described. FIG. 1 is a schematic diagram of a manufacturing apparatus 1 for an optical fiber according to an embodiment. The manufacturing apparatus 1 includes a drawing furnace 3, a cooling device 4, a coating device 5, a curing device 6, a directly-below roller 7, a traction roller 8, and a winding device 9 in order along the passage path of the optical fiber bare wire 10 and the optical fiber element wire 11. In this manufacturing apparatus 1, the optical fiber base material 2 is heated and melted to draw the optical fiber bare wire 10, and the optical fiber bare wire 10 is cooled to a predetermined temperature by the cooling device 4. Then, the cooled optical fiber bare wire 10 is coated with resin by the coating device 5 and the resin is cured by the curing device 6 to form the optical fiber element wire 11. Then, the direction of the optical fiber element wire 11 is changed by the directly-below roller 7 and the optical fiber element wire 11 is wound by the winding device 9. Hereinafter, each component of the manufacturing apparatus 1 and the manufacturing process in each component will be described in more detail.

[0020] The drawing furnace 3 forms the optical fiber bare wire 10 by heating and melting the optical fiber base material 2 and drawing it along the vertical direction. The drawing furnace 3 has a heater located around the optical fiber base material 2. The optical fiber base material 2 is a glass body (preform) containing, for example, quartz glass. The optical fiber bare wire 10 is, for example, a glass wire including a core and a cladding covering the outer periphery of the core. The drawing furnace 3 heats and softens the lower end of the optical fiber base material 2 by a heater so that drawing can be performed. The drawn optical fiber bare wire 10 is sent to the cooling device 4.

[0021] The cooling device 4 cools the bare optical fiber 10. The cooling device 4 has an internal space S enclosed by, for example, an outer wall, through which the bare optical fiber 10 passes. The outer wall of the cooling device 4 may be made of transparent glass or resin so that the inside of the cooling device 4 can be seen. The cooling device 4 may have an intake port (not shown) for injecting cooling gas into the internal space S to cool the bare optical fiber 10. The heat of the bare optical fiber 10 is released to the outside using the cooling gas as a coolant. The cooling device 4 may have an exhaust port (not shown) for discharging the cooling gas.

[0022] The coating device 5 applies a coating resin to the outer circumference of the bare optical fiber 10, which has been cooled to a predetermined temperature by the cooling device 4. The coating resin is, for example, an ultraviolet-curing resin. The coating device 5 may apply two different types of coating resin to the outer circumference of the bare optical fiber 10. For example, the coating device 5 may apply a primary resin to the bare optical fiber 10, and then apply a secondary resin to the outside of the primary resin. The coating device 5 may apply the primary resin and the secondary resin to the bare optical fiber 10 almost simultaneously. The bare optical fiber 10 coated with the coating resin is sent to the curing device 6. A measuring device for measuring the fiber diameter of the resin-coated optical fiber strand 11 may be provided immediately after the coating device 5.

[0023] The curing device 6 cures the coating resin applied to the bare optical fiber 10 by irradiating it with ultraviolet light. The curing device 6 has a light-emitting element such as an ultraviolet lamp that emits ultraviolet light. When the coating resin applied to the bare optical fiber 10 hardens, the optical fiber strand 11 is completed. The completed optical fiber strand 11 is sent to the roller 7 directly below. A measuring device for measuring the fiber diameter of the optical fiber strand 11 with the hardened coating resin may be provided immediately after the curing device 6.

[0024] The direct-below roller 7 is a non-rotating roller located directly below the coating device 5 and the hardening device 6, on the line drawing direction (vertical direction) connecting the optical fiber base material 2 and the coating device 5, and changes the direction of movement of the optical fiber strands 11 from the vertical direction to a predetermined direction. The optical fiber strands 11 whose direction of movement has been changed by the direct-below roller 7 are sent to the traction roller 8. The traction roller 8 pulls and moves the optical fiber strands 11. The movement speed of the optical fiber strands 11 can be adjusted by changing the rotation speed of the traction roller 8. The optical fiber strands 11 are sent from the traction roller 8 to the winding device 9 and wound up by the winding device 9. A tension meter may be installed in front of the traction roller 8 to measure the line drawing tension on the bare optical fiber 10 or the optical fiber strands 11.

[0025] The lower roller 7 is a disc-shaped member composed of a non-rotating guide roller, a non-contact guide 20 (see Figure 2), through which the optical fiber strands 11 are passed. The gap 80 has a groove shape and functions as a guide that can wind the optical fiber strands 11 in a non-rotating and non-contact manner. The width of the gap 80 may be adjustable based on the fiber diameter or tension of the optical fiber strands being guided. Inside the gap 80, there are multiple nozzles 47 (see Figure 4) that blow out gas to suspend the optical fiber strands 11. The lower roller 7 guides the optical fiber strands 11 in a non-rotating and non-contact manner, changing their direction by blowing gas outward from the nozzles 47.

[0026] Next, with reference to Figures 2 to 6, the structure of a non-contact guide 20, which is an example of a non-contact roller applied to the roller directly below 7, will be described. Figure 2 is a perspective view showing the non-contact guide 20. Figure 3 is an exploded perspective view of the non-contact guide 20 when disassembled along the central axis C. Figure 4 is a cross-sectional view of the non-contact guide 20 when cut along the line IV-IV shown in Figure 2. Figure 5 is an exploded perspective view of the internal member 40 when disassembled along the central axis C. Figure 6 is an enlarged view of the area A enclosed by the dashed line in Figure 4. Note that the non-contact roller applied to the roller directly below 7 may have a different configuration from the non-contact guide 20, as long as it can change the direction of the guiding optical fiber strands 11 in a non-contact state.

[0027] The non-contact guide 20 is a component that changes the direction of movement of the optical fiber strand 11. The non-contact guide 20 has a circular shape in plan view. As shown in Figure 2, the non-contact guide 20 has a gap 80 between the first flange 30 and the second flange 70. The gap 80 is provided in an annular shape along the outer circumference of the non-contact guide 20. The optical fiber strand 11 is passed through the gap 80. Gas introduced into the interior of the non-contact guide 20 is blown outward from the gap 80. The blown-out gas is blown onto the optical fiber strand 11 that is passed through the gap 80. The optical fiber strand 11 is suspended by the blown gas and does not come into contact with the first flange 30 and the second flange 70. As a result, even if the non-contact guide 20 is non-rotating, the direction of the optical fiber strand 11 can be changed without damaging it.

[0028] As shown in Figure 3, the non-contact guide 20 comprises a first flange 30, an internal member 40, and a second flange 70. The first flange 30 is a member provided on the side of the non-contact guide 20 and accommodates a part of the internal member 40. The first flange 30 has a circular disc portion 31 in plan view and a peripheral wall portion 32 formed along the outer circumference of the disc portion 31. As shown in Figure 3, the disc portion 31 is provided with one hole 31a and a plurality of screw holes 31b. The hole 31a is a through hole provided in the center of the disc portion 31. As shown in Figure 4, the shaft portion 42 of the internal member 40 can be inserted through the hole 31a. The plurality of screw holes 31b are small-diameter through holes scattered around the hole 31a. Each of the plurality of screw holes 31b can be inserted into a plurality of screws 90. The first flange 30 is fixed to the internal member 40 by the screws 90.

[0029] The peripheral wall portion 32 has an outer peripheral surface 32a facing the outside of the first flange 30 and an inner peripheral surface 32b facing the inside of the first flange 30 (the side of the first housing portion 33, which will be described later). As shown in Figure 4, the end of the outer peripheral surface 32a on the second flange 70 side curves inward toward the central axis C and connects to the end of the inner peripheral surface 32b. That is, the end of the outer peripheral surface 32a has a curved shape in cross-sectional view. A gap 80 is provided between the outer peripheral surface 32a and the outer peripheral surface 72a of the second flange 70, which will be described later, through which the optical fiber strands 11 pass. The Vickers hardness of the surface of the outer edge of the first flange 30 that defines the gap 80 (in this embodiment, the outer peripheral surface 32a) may be, for example, 800 HV or more, and more preferably 1500 HV or more. The Vickers hardness is measured according to JIS Z 2244:2009. Specifically, a square pyramidal diamond indenter is pressed into the surface of the sample (the outer surface 32a in this embodiment), and the Vickers hardness is determined from the diagonal length of the indentation remaining on the surface.

[0030] The first flange 30 has a first housing portion 33 in which a part of the internal member 40 is housed. The first housing portion 33 is a substantially cylindrical space defined by the surface of the disc portion 31 and the inner circumferential surface 32b of the peripheral wall portion 32. When the internal member 40 is housed in the first housing portion 33, as shown in Figure 4, the inner circumferential surface 32b of the peripheral wall portion 32 faces the first cylindrical surface 50 of the internal member 40.

[0031] The internal member 40 is a component that blows the introduced gas out to the outside through a gap 80 between the first flange 30 and the second flange 70. The internal member 40 has a disc shape. As shown in Figure 5, the internal member 40 comprises a main body 41 and a plate 60. As shown in Figure 4, the main body 41 has a shaft portion 42 extending along the central axis C and a cylindrical portion 43 provided at one end of the shaft portion 42. Inside the shaft portion 42, a first gas flow path 44 is formed, extending along the central axis C. The first gas flow path 44 has an opening 42b at the end face 42a of the shaft portion 42. The opening 42b is connected to an external gas supply source (such as an air pump). The gas supplied from the gas supply source flows into the first gas flow path 44 through the opening 42b. The end of the first gas flow path 44 located on the opposite side of the opening 42b is connected to a flow path branching portion 45 of the cylindrical portion 43. The gas flowing into the first gas flow path 44 is supplied to the flow path branch 45. The first gas flow path 44 is formed such that its inner diameter gradually decreases as it moves from the opening 42b side towards the flow path branch 45 side.

[0032] The cylindrical section 43 is a substantially cylindrical member and is housed between the first housing section 33 and the second housing section 73, which will be described later. The cylindrical section 43 has a flow path branching section 45, a plurality of second gas flow paths 46, and a plurality of nozzles 47. The flow path branching section 45 is an internal space that has a substantially cylindrical shape and branches the flow direction of the gas supplied from the first gas flow path 44 in multiple directions. The inner circumferential surface 45a defining the flow path branching section 45 has a plurality of openings provided at equal intervals along its circumferential direction. These plurality of openings are each connected to a plurality of second gas flow paths 46.

[0033] Multiple second gas flow channels 46 are arranged radially from the flow channel branching section 45 toward the outer circumferential surface of the cylindrical section 43 (see Figure 7). One end of each second gas flow channel 46 is connected to an opening provided on the inner circumferential surface 45a, as described above, and the other end is connected to an outlet 47 provided on the outer circumferential surface of the cylindrical section 43. Multiple outlets 47 are provided at equal intervals along the outer circumferential surface. The gas supplied from the first gas flow channel 44 remains in the flow channel branching section 45 before branching and flowing into the second gas flow channels 46. The gas that flows into the second gas flow channels 46 is ejected from the outlets 47. The gas ejected from the outlets 47 is blown onto the optical fiber strands 11 through the gap 80 via a buffer groove 51, which will be described later. In this embodiment, the cross-section of the second gas flow channel 46 is circular. The portion of the second gas flow channel 46 located on the outlet 47 side is formed to have a larger inner diameter than the portion located on the inner circumferential surface 45a side. The shape of the second gas flow path 46 is not limited to the shape described above. The cross-section of the second gas flow path 46 may be elliptical or polygonal. The second gas flow path 46 may also be a straight flow path with a constant cross-sectional area.

[0034] As shown in Figure 4, the outer surface of the cylindrical portion 43 has a first cylindrical surface 50, a buffer groove 51, and a second cylindrical surface 52 in that order along the central axis C. The first cylindrical surface 50 is located closer to the shaft portion 42 than the buffer groove 51. When the internal member 40 is housed in the first housing portion 33, the first cylindrical surface 50 faces the inner circumferential surface 32b of the peripheral wall portion 32. As shown in Figure 6, the first cylindrical surface 50 has a first groove portion 54. The first groove portion 54 is a recess that is recessed toward the inside of the internal member 40 (towards the central axis C shown in Figure 4), and is provided continuously in an annular shape along the first cylindrical surface 50. The first groove portion 54 is a bottomed rectangular groove and is defined by a bottom surface 54a and a pair of opposing side surfaces 54b.

[0035] A first sealing member 65 is fitted into the first groove 54. The first sealing member 65 may be an O-ring made of, for example, an elastic resin. The first sealing member 65 seals the gap between the first cylindrical surface 50 and the inner circumferential surface 32b of the peripheral wall 32, preventing the gas ejected from the nozzle 47 from flowing into the gap. The width of the first groove 54 (the distance between the pair of side surfaces 54b) in the direction along the central axis C is formed to be slightly larger than the width of the cross-section of the first sealing member 65. This allows the first flange 30 to move smoothly relative to the internal member 40.

[0036] The buffer groove 51 is a recess that curves toward the central axis C and is provided in a continuous annular shape along the outer circumferential surface of the internal member 40. The buffer groove 51 is a bottomed rectangular groove with multiple nozzles 47 provided on its bottom surface. The buffer groove 51 temporarily holds the gas ejected from the multiple nozzles 47 and then blows the gas out to the outside through the gap 80 between the first flange 30 and the second flange 70.

[0037] The second cylindrical surface 52 is located further from the shaft portion 42 than the buffer groove 51. When the internal member 40 is housed in the second housing portion 73, which will be described later, the second cylindrical surface 52 faces the inner circumferential surface 72b of the peripheral wall portion 72. As shown in Figure 6, the second cylindrical surface 52 has a second groove portion 56. The second groove portion 56 is a recess that is recessed on the inside of the internal member 40 (towards the central axis C shown in Figure 4) and is provided continuously in an annular shape along the second cylindrical surface 52. The second groove portion 56 is a bottomed rectangular groove and is defined by a bottom surface 56a and a pair of opposing side surfaces 56b.

[0038] A second sealing member 66 is fitted into the second groove 56. The second sealing member 66 may be an O-ring made of, for example, an elastic resin. The second sealing member 66 seals the gap between the second cylindrical surface 52 and the inner circumferential surface 72b of the peripheral wall 72, preventing the gas ejected from the nozzle 47 from flowing into the gap. The width of the second groove 56 (the distance between the pair of side surfaces 56b) in the direction along the central axis C is formed to be slightly larger than the width of the cross-section of the second sealing member 66. This allows the second flange 70 to move smoothly relative to the internal member 40.

[0039] As shown in Figure 5, the internal member 40 has a plate housing section 57. The plate housing section 57 is a substantially cylindrical space capable of housing a plate 60. The inner diameter of the plate housing section 57 is larger than the inner diameter of the flow channel branch section 45. The inner circumferential surface 57a defining the plate housing section 57 and the inner circumferential surface 45a defining the flow channel branch section 45 are connected by an inner surface 58. The inner surface 58 has an extension along a plane perpendicular to the central axis C and is provided in an annular shape surrounding the central axis C. The inner surface 58 is provided with a plurality of screw holes 58a, each to which a plurality of screws 91 for fixing the plate 60 to the main body section 41 are attached.

[0040] As shown in Figure 5, the plate 60 is a plate member having a circular shape in plan view. The plate 60 is housed in the plate housing portion 57 of the main body portion 41. The plate 60 has a first side surface 61, a second side surface 62, and an outer peripheral surface 63. The first side surface 61 and the second side surface 62 are surfaces that form the side surfaces of the plate 60 in the direction along the central axis C. The outer peripheral surface 63 is a surface that connects the outer edge of the first side surface 61 and the outer edge of the second side surface 62. When the plate 60 is housed in the plate housing portion 57, the region of the first side surface 61 closer to the outer peripheral surface 63 is in contact with the inner surface 58 of the plate housing portion 57. The central region of the first side surface 61 is not in contact with the inner surface 58 and functions as a wall surface that defines the flow path branch portion 45.

[0041] As shown in Figure 4, a third groove 61a is provided on the first side surface 61. The third groove 61a is provided in a continuous annular shape surrounding the central axis C. The third groove 61a is a bottomed rectangular groove into which a third sealing member 67 is fitted. The third sealing member 67 may be an O-ring made of, for example, an elastic resin. The third sealing member 67 seals the gap between the inner side surface 58 and the first side surface 61, preventing the gas supplied to the flow path branch 45 from leaking out through the gap.

[0042] As shown in Figure 5, the plate 60 is provided with a plurality of through holes 64 that penetrate from the first side surface 61 to the second side surface 62. The plurality of through holes 64 are arranged in an annular shape surrounding the central axis C. A plurality of screws 91 are inserted into each of the plurality of through holes 64. The tips of the screws 91 inserted into the through holes 64 are attached to the screw holes 58a of the main body 41. In this way, the plate 60 is fixed to the main body 41 while housed in the plate housing 57.

[0043] The second flange 70 is provided on the side of the non-contact guide 20 and is a member that accommodates a part of the internal member 40. The second flange 70 has the same configuration as the first flange 30. As shown in Figure 3, the second flange 70 is located on the opposite side from the first flange 30 in the direction along the central axis C and is attached to the internal member 40 in an inverted orientation from the first flange 30. In other words, in this embodiment, one flange can be used for both the first flange 30 and the second flange 70, so it is not necessary to prepare flanges of different shapes for the first flange 30 and the second flange 70.

[0044] The second flange 70 has a circular disc portion 71 in plan view and a peripheral wall portion 72 formed along the outer circumference of the disc portion 71. As shown in Figure 3, the disc portion 71 is provided with one hole 71a and a plurality of screw holes 71b. The hole 71a is a through hole provided in the center of the disc portion 71. The plurality of screw holes 71b are small-diameter through holes scattered around the hole 31a. When the second flange 70 is replaced in the position of the first flange 30, the shaft portion 42 of the internal member 40 can be inserted through the hole 71a, and the plurality of screws 90 can be inserted through the plurality of screw holes 71b.

[0045] The peripheral wall portion 72 has an outer peripheral surface 72a facing the outside of the second flange 70 and an inner peripheral surface 72b facing the inside of the second flange 70 (the side of the second housing portion 73, which will be described later). As shown in Figure 4, the end of the outer peripheral surface 72a on the first flange 30 side curves inward toward the central axis C and connects to the end of the inner peripheral surface 72b. That is, the end of the outer peripheral surface 72a has a curved shape in cross-sectional view. A gap 80 is provided between the outer peripheral surface 72a of the second flange 70 and the outer peripheral surface 32a of the first flange 30 through which the bare optical fiber 10 passes, as described above. The Vickers hardness of the surface of the outer edge of the second flange 70 that defines the gap 80 (in this embodiment, the outer peripheral surface 72a) may be, for example, 800 HV or more, and more preferably 1500 HV or more. The method for measuring the Vickers hardness is the same as the method for measuring the Vickers hardness of the surface of the first flange 30 described above.

[0046] The second flange 70 has a second housing portion 73 in which a part of the internal member 40 is housed. The second housing portion 73 is a substantially cylindrical space defined by the surface of the disc portion 71 and the inner circumferential surface 72b of the peripheral wall portion 72. When the internal member 40 is housed in the second housing portion 73, as shown in Figure 4, the inner circumferential surface 72b of the peripheral wall portion 72 faces the second cylindrical surface 52 of the internal member 40. The second flange 70 is not fixed to the internal member 40 and is movable relative to the internal member 40. The second flange 70 may be detachable from the internal member 40. The detachability of the second flange 70 makes it easy to perform maintenance on the gap 80 (such as removing bare optical fibers 10 stuck in the gap 80 or checking for scratches on the outer circumferential surfaces 32a and 72a).

[0047] Referring to Figures 6 and 7, the configuration of the non-contact guide 20 when an optical fiber strand 11 is passed through the gap 80 will be described. Figure 7 is a cross-sectional view of the non-contact guide 20 when cut along the line VII-VII shown in Figure 2. The first flange 30 and the second flange 70 are attached to the internal member 40 such that a gap 80 is provided between the outer edge of the first flange 30 and the outer edge of the second flange 70, as shown in Figure 6. In this embodiment, a gap 80 is provided between the outer circumferential surface 32a of the first flange 30 and the outer circumferential surface 72a of the second flange 70.

[0048] As shown in Figure 7, the gap 80 is provided along the circumferential direction of the non-contact guide 20, surrounding the central axis C. The optical fiber strands 11 are passed through the gap 80. Specifically, the optical fiber strands 11 enter the gap 80 from the entry point 81, move along the gap 80, and then exit to the outside from the exit point 82. In the example shown in Figure 7, the optical fiber strands 11 move over approximately one-third of the circumferential area of ​​the gap 80. That is, the non-contact guide 20 changes the direction of movement of the optical fiber strands 11 by approximately 120°. The positions of the entry point 81 and exit point 82 described above are determined by the amount of change in the direction of movement of the optical fiber strands 11. In this embodiment, as described above, the direction of movement of the optical fiber strands 11 is changed by approximately 120°. Therefore, the exit point 82 is set at a position offset from the entry point 81 by approximately one-third of the length of the circumferential direction of the gap 80. For example, if the direction of movement of the optical fiber strand 11 is changed by approximately 90°, the exit portion 82 may be set at a position shifted from the entry portion 81 by approximately one-quarter of the circumferential length of the gap 80 (the lower part of the gap 80 in Figure 7).

[0049] As shown in Figure 6, the gap 80 is spatially connected to the buffer groove 51 and the nozzle 47. As a result, the gas ejected from the nozzle 47 passes through the buffer groove 51 and is blown out of the gap 80 to the outside of the non-contact guide 20. The gas ejected from the gap 80 is blown onto the optical fiber strands 11 that are passed through the gap 80. The air pressure of the gas maintains a state in which the optical fiber strands 11 are suspended above the outer circumferential surface 32a of the first flange 30 and the outer circumferential surface 72a of the second flange 70. In other words, the optical fiber strands 11 are suspended in the gap 80.

[0050] The second flange 70 is not fixed to the internal member 40 and is movable in a direction that changes the width W of the gap 80. The width W of the gap 80 is the distance between the closest points of the outer circumferential surfaces 32a of the first flange 30 and 72a of the second flange 70, which are opposite each other. The method of moving the second flange 70 is not limited. For example, the width W of the gap 80 may be changed by moving the second flange 70 in a direction along the central axis C. As another example, the width W of the gap 80 may be changed by rotating the second flange 70 in the direction of arrow T with respect to the virtual point P shown in Figure 4. In this case, the width W of the part of the gap 80 closer to the virtual point P (the lower part in Figure 4) becomes smaller, and the width W of the part further from the virtual point P (the upper part in Figure 4) becomes larger.

[0051] The pressure of the gas blown out from the gap 80 (blow-out pressure) changes depending on factors such as the pressure of the gas supplied to the first gas flow path 44 (see Figure 4) (inlet pressure), the width W of the gap 80, and is also affected by factors such as the winding diameter D1 of the non-contact guide 20. Here, the winding diameter D1 refers to the diameter of the circle formed by the optical fiber strands 11 (circle B shown by solid and dashed lines in Figure 7) when the optical fiber strands 11 are passed around the entire circumference of the gap 80. The blow-out pressure is optimized by adjusting each of the above factors (groove width) according to the tension (draw tension) of the optical fiber strands 11 or the fiber diameter of the optical fiber strands 11.

[0052] Generally, when increasing the linear velocity (moving speed) of the optical fiber strand 11, the tension on the optical fiber strand 11 is small, and if the pressure of the blown gas is high, the optical fiber strand 11 will resonate and come into contact with the non-contact guide 20. Therefore, the blown pressure is reduced when increasing the linear velocity of the optical fiber strand 11. On the other hand, when the linear velocity is stable, the tension on the optical fiber strand 11 is maintained at a high level, so the blown pressure is increased. Methods for increasing the blown pressure include, for example, increasing the inlet pressure or reducing the width W of the gap 80.

[0053] For example, when suspending an optical fiber strand 11 with a diameter of 250 μm, the width W of the gap 80 is adjusted so that the inlet pressure is within the optimal pressure range of 50 kPa to 200 kPa. At this time, the flow rate of gas blown out from the gap 80 of one non-contact guide 20 may be between 30 L / min and 150 L / min.

[0054] When adjusting the discharge pressure to an appropriate level, first, with a constant flow rate of gas flowing, the width W of the gap 80 is reduced until the inlet pressure reaches a predetermined value (for example, 200 kPa). At this time, the width W of the gap 80 may be reduced by, for example, bringing the second flange 70 closer to the first flange 30. After that, the width W of the gap 80 is gradually increased until the discharge pressure reaches an optimal level (a level in which the optical fiber strands 11 can float properly). At this time, the width W of the gap 80 may be increased by, for example, moving the second flange 70 away from the first flange 30. This adjustment work may be performed at any time during the manufacturing process of the optical fiber strands 11.

[0055] The non-contact guide 20 has a sealing member 68, as shown in Figure 7. For convenience of explanation, the sealing member 68 is not shown in figures other than Figure 7. The sealing member 68 seals at least one of the multiple nozzles 47, preventing gas from passing through the nozzle 47. The sealing member 68 may be made of an elastic material such as resin. The sealing member 68 has an elongated shape and is fitted into a portion of the buffer groove 51 so as to block the nozzle 47. In this embodiment, the sealing member 68 is fitted into approximately two-thirds of the buffer groove 51. Gas does not flow into the portion of the second gas flow path 46 where the nozzle 47 is sealed by the sealing member 68, but gas flows into the other second gas flow paths 46 where the nozzle 47 is not sealed.

[0056] In the direction from the central axis C toward the outer circumference of the non-contact guide 20 (radial direction of the non-contact guide 20), most of the sealing member 68 is positioned so as not to overlap with the bare optical fiber 10 passed through the gap 80. In the example shown in Figure 7, the parts of the sealing member 68 excluding both ends are positioned so as not to overlap with the optical fiber strands 11 passed through the gap 80 in the circumferential direction. In addition, a pair of gas escape parts 84 are provided between both ends of the sealing member 68 and the optical fiber strands 11, allowing the gas inside the buffer groove 51 to flow out. By allowing the gas accumulated in the buffer groove 51 to flow out smoothly from the gas escape parts 84, excessively high-pressure gas is not blown out from the gap 80, making it possible to suspend the optical fiber strands 11 in a stable state. The shape of the sealing member 68 is not limited to that described above. In this embodiment, multiple nozzles 47 are sealed by a single continuous sealing member 68, but for example, multiple nozzles 47 may be sealed by multiple separate sealing members 68.

[0057] Here, we will explain the effects of applying the non-contact guide 20 described above to the roller directly below the roller 7. Conventionally, the roller directly below the roller 7 uses a roller that rotates with a bearing, but with this roller, minute vibrations (vertical vibrations, amplitude of about 0.1 mm) can occur due to the misalignment between the rotation axis and the perpendicularity of the roller (for example, a misalignment of about 30 μm to 50 μm). These minute vibrations propagate to the optical fiber strands 11 (for example, with a diameter of 170 μm to 250 μm) and the bare optical fiber wires 10 connected to them that are guided by the roller directly below, causing the bare optical fiber wires 10 to vibrate. When the bare optical fiber wires 10 vibrate, the bare optical fiber wires 10 that are being coated with resin in the coating device 5 deviate slightly horizontally from the predetermined path, causing uneven thickness in the coating resin when they become optical fiber strands 11.

[0058] In contrast, in this embodiment, by applying a non-contact guide 20 to the roller directly below 7, when winding the resin-coated optical fiber strand 11, the optical fiber strand 11 is changed in a non-rotating manner by the non-contact roller directly below 7. In this non-contact roller, the optical fiber strand 11 is suspended by gas, that is, the optical fiber strand 11 is transported and wound in a non-rotating, non-contact state. Therefore, since the roller directly below does not rotate and the resin-coated optical fiber strand 11 can be changed in direction without contacting the roller, vibrations from the non-contact roller are not transmitted to the bare optical fiber 10, etc. With a non-contact roller, vibrations from various devices downstream of the non-contact roller (e.g., winding device 9, etc.) are also attenuated by the suspension on the non-contact roller and are less likely to be transmitted to the bare optical fiber 10, etc. As described above, according to this embodiment, it is possible to manufacture optical fibers in which the resin coating of the bare optical fiber 10 is appropriately performed and variations such as uneven coating thickness are suppressed.

[0059] In this embodiment, the guide portion of the lower roller 7 is provided with a gap 80 that communicates with the nozzle 47 and extends along the outer surface, and the width of the gap 80 is adjustable. In this case, the stability of the floating of the optical fiber strands 11 on the lower roller 7, which is responsible for changing the direction of the optical fiber strands 11, can be easily controlled by adjusting the width of the gap 80. As a result, optical fibers can be manufactured with suppressed variations such as uneven coating thickness over a long period of time.

[0060] In this embodiment, the tension applied to the bare optical fiber 10 can also be measured using a measuring device. In this case, during the winding process of the optical fiber strands 11, the width of the gap 80 in the non-contact guide 20 is adjusted by a control device based on the measured tension, and the optical fiber strands 11 are wound via the lower roller 7. In this control, by blowing gas at a blowing pressure corresponding to the tension, the optical fiber strands 11 can be guided by the lower roller 7, which is a non-contact roller, while maintaining an appropriate amount of suspending air. Therefore, according to this embodiment, it is possible to manufacture optical fibers with further suppression of variations such as uneven coating thickness.

[0061] In this embodiment, the fiber diameter of the optical fiber strand 11 can also be measured using a measuring device. In this case, during the winding process of the optical fiber strand 11, the width of the gap 80 of the non-contact guide 20 is adjusted by a control device based on the measured fiber diameter, and the optical fiber strand 11 is wound via the direct roller 7. This control allows the optical fiber strand 11 to be guided by the direct roller 7, which is a non-contact roller, while maintaining an appropriate amount of buoyancy by adjusting the gap width according to the fiber diameter of the optical fiber strand 11. Therefore, according to this embodiment, it is possible to manufacture optical fibers that further suppress variations such as uneven coating thickness. Alternatively, both the wire drawing tension and the fiber diameter of the optical fiber strand 11 may be measured, and the width of the gap 80 of the direct roller 7 may be adjusted based on these values.

[0062] In this embodiment, the non-contact guide 20 constituting the direct-below roller 7 includes, as an example, an internal member 40 having a plurality of nozzles 47 on its outer circumferential surface, and a first flange 30 and a second flange 70 that house the internal member 40 so as to sandwich it in a horizontal direction intersecting the ejection direction of the gas ejected from the plurality of nozzles 47. The second flange 70 is attached to the internal member 40 such that a gap 80 for the gas ejected from the plurality of nozzles 47 to pass through is provided between the outer edge of the first flange 30 and the outer edge of the second flange 70. At least one of the first flange 30 and the second flange 70 (for example, the second flange 70) is movable in a direction that changes the width of the gap 80. In this case, the stability of the floating of the optical fiber strands 11 by the non-contact guide 20 can be easily adjusted with a simple configuration. This makes it possible to manufacture optical fibers by easily suppressing variations such as uneven coating thickness. In this embodiment, the roller directly below 7 does not rotate, and the resin-coated optical fiber strands 11 can be changed direction without contacting the roller. Therefore, the optical fiber does not roll in the grooves of the roller directly below 7. For this reason, even when a multi-core optical fiber is used, no twisting occurs in the longitudinal direction.

[0063] Although embodiments relating to this disclosure have been described in detail above, the present invention is not limited to the above embodiments and can be applied to various embodiments. For example, the non-contact roller applied to the direct-below roller 7 is not limited to a roller having the configuration shown in Figure 2, etc., and is not limited to a non-contact guide having a guide portion along its outer surface on which a part of the optical fiber strand 11 can be wound, and which has a plurality of nozzles for blowing gas to suspend the optical fiber strand 11 in this guide portion. Furthermore, if a roller other than the direct-below roller 7 is provided, for example, between the covering device 5 and the winding device 9, this roller may also be a non-rotating non-contact roller in the same manner as described above. [Explanation of Symbols]

[0064] 1...Manufacturing equipment 2… Optical fiber base material 3…Line drawing furnace 4…Cooling device 5... Covering device 6...Curing device 7... Directly below roller 8... Towing roller 9... Winding device 10… Bare fiber optic cable 11… Optical fiber strand 20... Contactless Guide 30…First flange 31, 71... Disc section 31a, 71a...hole 31b, 71b... screw holes 32, 72...peripheral wall part 32a, 72a...outer surface 32b, 72b…Inner peripheral surface 33…First Detention Unit 40…Internal components 41...Main body 42... Shaft 42a...end face 42b…Aperture 43...Cylindrical section 44…First gas flow path 45... Channel branching point 45a…Inner peripheral surface 46…Second gas flow path 47... spout 50...First cylindrical surface 51... Buffer groove 52...Second cylindrical surface 54...First trench section 54a, 56a...Bottom 54b, 56b...side 56...Second trench section 57...Plate housing section 57a…Inner peripheral surface 58…Inner surface 58a... screw hole 60... Plate 61…1st side 61a...Third groove 62…Second side 63...Outer surface 64…Through hole 65...First sealing member 66...Second sealing member 67...Third sealing member 68...Sealing member 70...Second flange 73...Second Detention Unit 80... Gap 81...Entry point 82…Outgoing line part 84...Gas escape unit 90, 91... screws A…Area B... yen C…Central axis D1...Wrap diameter P...Virtual point S…interior space T...arrow W…width

Claims

1. The process involves melting the optical fiber preform and drawing bare optical fiber wires, A step of forming optical fiber strands by coating the bare optical fiber with resin using a coating device, A step of changing the direction of the optical fiber strands with a roller directly below and winding the optical fiber strands with a winding device, The process of measuring the tension of the line, Equipped with, The roller directly below is a non-rotating guide roller. The non-rotating guide roller is a non-contact guide having a guide portion along its outer surface on which a portion of the optical fiber strands can be wound, and the guide portion of the non-contact guide is provided with a plurality of nozzles for blowing out gas that suspends the optical fiber strands. The guide portion of the non-contact guide is provided with a gap that communicates with the nozzle and extends along the outer circumferential surface, and the width of the gap is adjustable. In the winding step, the width of the gap in the non-contact guide is adjusted based on the measured wire tension, and the optical fiber strand is wound through the non-contact guide. A method for manufacturing optical fibers.

2. The process involves melting the optical fiber preform and drawing bare optical fiber wires, A step of forming optical fiber strands by coating the bare optical fiber with resin using a coating device, A step of measuring the fiber diameter of the optical fiber strand, A step of changing the direction of the optical fiber strands with a roller directly below and winding the optical fiber strands with a winding device, Equipped with, The roller directly below is a non-rotating guide roller. The non-rotating guide roller is a non-contact guide having a guide portion along its outer surface on which a portion of the optical fiber strands can be wound, and the guide portion of the non-contact guide is provided with a plurality of nozzles for blowing out gas that suspends the optical fiber strands. The guide portion of the non-contact guide is provided with a gap that communicates with the nozzle and extends along the outer circumferential surface, and the width of the gap is adjustable. In the winding step, the width of the gap in the non-contact guide is adjusted based on the measured fiber diameter, and the optical fiber strand is wound through the non-contact guide. A method for manufacturing optical fibers.

3. The aforementioned non-contact guide is An internal member having the aforementioned plurality of nozzles on its outer surface, It comprises a first flange and a second flange that house the internal member so as to sandwich it in a first direction intersecting the gas ejection direction of the gas ejected from the plurality of nozzles, At least one of the first flange and the second flange is attached to the internal member such that the gap for passing the gas ejected from the plurality of nozzles is provided between the outer edge of the first flange and the outer edge of the second flange, At least one of the first flange and the second flange is movable in a direction that changes the width of the gap. A method for manufacturing an optical fiber according to claim 1 or claim 2.

4. Move at least one of the first flange and the second flange to adjust the width of the gap. The method for manufacturing an optical fiber according to claim 3.

5. A melting apparatus for melting the optical fiber preform in order to draw bare optical fiber wires from the optical fiber preform, A coating apparatus for forming optical fiber strands by coating the aforementioned bare optical fiber with resin, A winding device for winding the aforementioned optical fiber strands, A roller located between the covering device and the winding device in the path of the optical fiber strand, which changes the direction of the optical fiber strand, A measuring device for measuring the tension applied to the bare optical fiber, Control device and Equipped with, The roller directly below is a non-rotating guide roller. The non-rotating guide roller is a non-contact guide having a guide portion along its outer surface on which a portion of the optical fiber strands can be wound, and the guide portion of the non-contact guide is provided with a plurality of nozzles for blowing out gas that suspends the optical fiber strands. The guide portion of the non-contact guide is provided with a gap that communicates with the nozzle and extends along the outer circumferential surface, and the width of the gap is adjustable. The control device adjusts the width of the gap in the non-contact guide based on the line tension. Optical fiber manufacturing equipment.

6. A melting apparatus for melting the optical fiber preform in order to draw bare optical fiber wires from the optical fiber preform, A coating apparatus for forming optical fiber strands by coating the aforementioned bare optical fiber with resin, A winding device for winding the aforementioned optical fiber strands, A roller located between the covering device and the winding device in the path of the optical fiber strand, which changes the direction of the optical fiber strand, A measuring device for measuring the fiber diameter of the optical fiber strand, Control device and Equipped with, The roller directly below is a non-rotating guide roller. The non-rotating guide roller is a non-contact guide having a guide portion along its outer surface on which a portion of the optical fiber strands can be wound, and the guide portion of the non-contact guide is provided with a plurality of nozzles for blowing out gas that suspends the optical fiber strands. The guide portion of the non-contact guide is provided with a gap that communicates with the nozzle and extends along the outer circumferential surface, and the width of the gap is adjustable. The control device adjusts the width of the gap in the non-contact guide based on the fiber diameter. Optical fiber manufacturing equipment.

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