Optical fiber manufacturing device and optical fiber manufacturing method

Abstract

The present invention is provided with: a drawing furnace for melting a glass base material and discharging drawn glass fibers; a coating unit that coats the glass fiber with a resin layer to form an optical fiber; a lower roller disposed directly below the drawing furnace and changing the traveling direction of the optical fiber; and a winch that picks up the optical fiber. When the front lower roller is viewed from a direction orthogonal to a rotation axis of the front lower roller, a traveling surface on which the optical fiber travels on the front lower roller is flat or convex, and the width of the traveling surface is from 2 mm to 10 mm (inclusive).

Description

Technical Field

[0001] The present invention relates to an optical fiber manufacturing device and an optical fiber manufacturing method.

[0002] This application is based on Japanese patent application No. 2022-

[0003] The present application claims priority as set forth in Application No. 117784, and all the contents described in the aforementioned application are cited herein. Background Art

[0004] Patent Document 1 discloses an optical fiber manufacturing apparatus.

[0005] Patent Document 1: Japanese Utility Model Application Laid-Open No. 5-27027 Summary of the invention

[0006] An optical fiber manufacturing device according to one embodiment of the present invention includes:

[0007] A drawing furnace, which melts the glass matrix and draws the glass fiber into a wire;

[0008] A coating unit, which coats the glass fiber with a resin layer to form an optical fiber;

[0009] A lower roller, which is arranged directly below the drawing furnace and changes the traveling direction of the optical fiber; and

[0010] a capstan which picks up the optical fiber,

[0011] If the positive lower roller is viewed from a direction orthogonal to the rotation axis of the positive lower roller, the running surface of the positive lower roller on which the optical fiber runs is flat or convex.

[0012] The width of the running surface is greater than or equal to 2 mm and less than or equal to 10 mm.

[0013] In one embodiment of the present invention, a method for manufacturing an optical fiber includes coating a glass fiber drawn from a glass base material in a drawing furnace with a resin to obtain an optical fiber.

[0014] In the method for manufacturing the optical fiber,

[0015] A positive lower roller disposed just below the drawing furnace to change the traveling direction of the optical fiber guides the optical fiber so that the optical fiber contacts only one point when observing a cross section of the optical fiber in contact with the positive lower roller. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram showing an example of an optical fiber manufacturing apparatus according to an embodiment of the present invention.

[0017] Figure 2 Yes means Figure 1 A diagram showing an example of a lower roller of a manufacturing apparatus.

[0018] Figure 3 This is a cross-sectional view showing an example of a lower roller.

[0019] Figure 4 It is a cross-sectional view showing a comparative example of a lower roller.

[0020] Figure 5 This is a cross-sectional view showing an example of a lower roller according to a first modification.

[0021] Figure 6 It means in Figure 5 A cross-sectional view of the bottom roller is shown, showing the situation in which the optical fiber deviates from the center and runs.

[0022] Figure 7 This is a cross-sectional view showing an example of a lower roller according to a second modification.

[0023] Figure 8 It means in Figure 7 A cross-sectional view of the bottom roller is shown, showing the situation in which the optical fiber deviates from the center and runs. DETAILED DESCRIPTION

[0024] (Problems to be solved by the invention)

[0025] The optical fiber manufacturing device of Patent Document 1 is provided with a coating unit (female mold) which coats a glass fiber manufactured by melting a glass matrix in a drawing furnace with a resin layer to form an optical fiber. In addition, a guide roller having a V-shaped running surface for changing the running direction of the optical fiber is provided directly below the drawing furnace and the female mold.

[0026] Furthermore, when manufacturing optical fibers using guide rollers with V-shaped running surfaces, the optical fibers may be unexpectedly twisted due to rolling on the V-shaped slopes of the guide rollers. Due to the twisting of the optical fibers, a load greater than necessary may be applied to the optical fibers.

[0027] (Effects of the Invention)

[0028] According to the present invention, it is possible to provide a manufacturing apparatus and a manufacturing method for manufacturing an optical fiber having less unexpected twist.

[0029] (Description of Embodiments of the Invention)

[0030] First, embodiments of the present invention will be described by way of examples.

[0031] An optical fiber manufacturing device according to one embodiment of the present invention,

[0032] (1) Having:

[0033] A drawing furnace, which melts the glass matrix and draws the glass fiber into a wire;

[0034] A coating unit, which coats the glass fiber with a resin layer to form an optical fiber;

[0035] A lower roller, which is arranged directly below the drawing furnace and changes the traveling direction of the optical fiber; and

[0036] a capstan which picks up the optical fiber,

[0037] If the positive lower roller is viewed from a direction orthogonal to the rotation axis of the positive lower roller, the running surface of the positive lower roller on which the optical fiber runs is flat or convex.

[0038] The width of the running surface is greater than or equal to 2 mm and less than or equal to 10 mm.

[0039] According to the above-mentioned manufacturing device, the running surface on which the optical fiber runs in the positive lower roller is flat or convex, so if the positive lower roller is observed from a direction orthogonal to the rotation axis of the positive lower roller, the optical fiber and the running surface are in contact at one point. In addition, the width of the running surface is greater than 2 mm and less than 10 mm, so even if a flange is provided outside the width of the running surface of the positive lower roller, it is not easy to contact the flange. In addition, the optical fiber running on the running surface of the positive lower roller is always subjected to a force toward the rotation axis of the positive lower roller. At this time, when the optical fiber runs on the positive lower roller having a flat or convex running surface, the optical fiber is less likely to roll on the running surface compared to the case where the optical fiber runs on the positive lower roller having a V-shaped running surface, so the torsion of the optical fiber after manufacturing can be suppressed.

[0040] (2) In the manufacturing device of (1) above, when the optical fiber travels in the center of the travel surface, the direction of the rotation axis of the positive lower roller may be perpendicular to the travel direction of the optical fiber on the travel surface.

[0041] When the direction of the rotation axis of the positive lower roller is perpendicular to the traveling direction of the optical fiber on the traveling surface, the optical fiber is unlikely to roll in the width direction of the traveling surface as long as the optical fiber travels in the center of the traveling surface.

[0042] (3) In the manufacturing apparatus of (1) or (2) above, the rotation axis of the positive lower roller may be supported by an elastic member.

[0043] When the optical fiber travels at a position other than the center of the running surface, the optical fiber travels in a direction slightly different from the direction when the optical fiber travels at the center of the running surface. According to the above-mentioned manufacturing device, the rotation axis of the positive lower roller is supported by the elastic member, so that the rotation axis of the positive lower roller can swing to a certain extent. Therefore, even when the optical fiber travels at a position other than the center of the running surface, the direction of the positive lower roller can be adjusted so that the direction of the rotation axis becomes perpendicular to the running direction of the optical fiber, so that the optical fiber is not easy to roll in the width direction of the running surface.

[0044] (4) In the manufacturing device according to any one of (1) to (3) above, the running surface of the positive lower roller may be convex when the positive lower roller is viewed from a direction orthogonal to the rotation axis of the positive lower roller,

[0045] The curvature radius of the running surface of the positive lower roller is greater than or equal to the distance from a point where the optical fiber separates from the running surface to a point where the optical fiber contacts the capstan.

[0046] According to the manufacturing device, the running surface is convex, so that even if the running direction of the optical fiber deviates, there is a running surface perpendicular to the running direction. Therefore, the optical fiber is not easy to roll in the width direction of the running surface.

[0047] (5) In the manufacturing apparatus of any one of (1) to (4) above, the running surface may be formed of a fluororesin.

[0048] According to the above manufacturing apparatus, the frictional force on the running surface can be reduced, so when the optical fiber attempts to roll in the width direction of the running surface, the twisting of the optical fiber that may be caused by the frictional force can be suppressed.

[0049] (6) In the manufacturing apparatus of any one of (1) to (5) above, the lower roller may be composed of a plurality of rollers,

[0050] The plurality of rollers are arranged such that the rotation axes of the plurality of rollers are arranged in an arc shape when viewed from the rotation axis direction of the rollers.

[0051] According to the manufacturing device, the lower roller is composed of a plurality of rollers, so the change of the traveling direction of the optical fiber is performed by the plurality of rollers, compared with the case where the lower roller is composed of a single roller. At this time, the plurality of rollers are arranged in a circular arc shape, so the change of the traveling direction of the optical fiber is performed sequentially for each roller. That is, the angle of the traveling direction changed by one roller becomes smaller, the length of contact between one roller and the optical fiber also becomes shorter, and the friction between one roller and the optical fiber is reduced, so that the twisting of the optical fiber due to the friction can be suppressed. In addition, the longer the time and distance that the optical fiber is in contact with one roller, the easier it is for the optical fiber to roll in the width direction of the traveling surface. However, by configuring the lower roller with a plurality of rollers and finely setting the time and distance that the optical fiber is in contact with one roller, the amount of twist in one roller can be suppressed, so the amount of twist transmitted to the upstream side and the distance that the twist is transmitted to the upstream side can be reduced.

[0052] (7) In the manufacturing apparatus of any one of (1) to (6) above, a second guide roller may be further provided on the downstream side of the positive lower roller, along which the optical fiber travels after the positive lower roller.

[0053] The second guide roller is disposed so that the rotation axis of the second guide roller and the rotation axis of the lower roller are perpendicular to each other.

[0054] According to the manufacturing device, the second guide roller is arranged so that the rotation axis of the front lower roller and the rotation axis of the second guide roller are perpendicular, so that the directions in which the optical fiber is supported by the front lower roller and the second guide roller are different. As a result, when the optical fiber travels on the travel surface of the front lower roller, it is difficult to roll in the width direction of the travel surface.

[0055] In addition, a method for manufacturing an optical fiber according to one embodiment of the present invention includes:

[0056] (8) The glass fiber drawn from the glass matrix in the drawing furnace is coated with resin to form an optical fiber,

[0057] A positive lower roller disposed just below the drawing furnace to change the traveling direction of the optical fiber guides the optical fiber so that the optical fiber contacts only one point when observing a cross section of the optical fiber in contact with the positive lower roller.

[0058] According to the manufacturing method, the running direction of the optical fiber is changed by using a positive lower roller that contacts the optical fiber at only one point when the cross section of the optical fiber in contact with the positive lower roller is observed. In this case, the roller and the optical fiber are in contact at only one point, so that the optical fiber is less likely to roll on the running surface compared to a positive lower roller that guides the optical fiber by contacting at two points such as a V-shaped running surface.

[0059] (Details of Embodiments of the Invention)

[0060] Hereinafter, specific examples of the optical fiber manufacturing device and the optical fiber manufacturing method according to the embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the present invention is not limited to these examples, but is shown by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims.

[0061] Figure 1 1 is a schematic diagram showing an example of a manufacturing apparatus 1 according to an embodiment of the present invention. Figure 1 As shown, the manufacturing device 1 has a drawing furnace 2 at the most upstream side, and the drawing furnace 2 melts the glass matrix G for the optical fiber and produces a glass fiber G1 drawn out. In the drawing furnace 2, a heating element 21 is provided to surround the glass matrix G, and a heating area is formed in which the glass matrix G can be softened by the heating element 21. Although not shown in the figure, a gas supply device for supplying a purge gas to the heating area is connected to the drawing furnace 2.

[0062] The glass matrix G is fed into the drawing furnace 2 so that the lower end of the glass matrix G is located in the heating area formed by the heating element 21. The glass matrix G is drawn downward and reduced in diameter to form a glass fiber G1 which is an optical fiber before resin coating.

[0063] A cooling device 3 for cooling the glass fiber G1 is provided below (on the downstream side) the drawing furnace 2. A cooling gas such as helium is used as a cooling means of the cooling device 3. The glass fiber G1 is formed so that its outer diameter has a predetermined dimension.

[0064] A coating unit 4 is provided on the downstream side of the cooling device 3, which coats the glass fiber G1 with a resin layer to form the optical fiber G2. The coating unit 4 includes: a coating unit 41, which coats the glass fiber G1 with a resin; and a curing unit 42, which cures the coated resin. The coating unit 41 coats the glass fiber G1 with, for example, an ultraviolet curing resin. In the case where the coated resin is an ultraviolet curing resin, the curing unit 42 irradiates ultraviolet rays to the resin coated by the coating unit 41 to cure the resin. The glass fiber G1 that has passed through the coating unit 41 and the curing unit 42 is coated with a resin layer on its outer periphery to form the optical fiber G2.

[0065] After passing through the curing unit 42, the optical fiber G2 is hooked on the lower roller 5 disposed directly below the drawing furnace 2, and its traveling direction is changed by the lower roller 5. Figure 1 As shown, the positive lower roller 5 changes the traveling direction of the optical fiber G2 traveling in the vertical direction on the upstream side of the positive lower roller 5 so that the optical fiber G2 travels in the horizontal direction on the downstream side of the positive lower roller 5 .

[0066] The optical fiber G2 whose traveling direction is changed by the lower roller 5 is hooked on the second guide roller 6 provided on the downstream side of the lower roller 5. Figure 1In the example shown, the optical fiber G2 is guided by the lower roller 5 and the second guide roller 6 .

[0067] The details of the lower roller 5 and the second guide roller will be described later.

[0068] The optical fiber G2 that has passed through the second guide roller 6 is taken up by a capstan 7 provided on the downstream side of the second guide roller 6 , and then is wound around a winding bobbin 8 .

[0069] Next, regarding the lower roller 5 and the second guide roller 6, refer to Figure 2 Provide explanation. Figure 2 Yes means Figure 1 A partially enlarged view of the bottom roller 5 and the second guide roller 6 of the manufacturing device 1 is shown.

[0070] like Figure 2 As shown in FIG. 1 , the first guide roller that initially contacts the optical fiber G2, i.e., the lower roller 5, is composed of a plurality of (five in this example) rollers 51, 52, 53, 54, and 55. The five rollers 51, 52, 53, 54, and 55 are arranged in sequence from a position below the curing unit 42 provided on the upstream side toward a position to the left of the second guide roller 6 provided on the downstream side. The rollers 51, 52, 53, 54, and 55 may be arranged so that when viewed from the direction of the rotation axis of the rollers, the rotation axes 51a, 52a, 53a, 54a, and 55a of the rollers 51, 52, 53, 54, and 55 (see also FIG. 1 ) are arranged so that the rotation axes 51a, 52a, 53a, 54a, and 55a of the rollers 51, 52, 53, 54, and 55 are arranged in sequence. Figure 3 ) are arranged in an arc shape.

[0071] The second guide roller 6 is a roller with which the optical fiber G2 contacts after contacting the rollers 51, 52, 53, 54, 55. The second guide roller 6 is arranged so that the rotation axis 6a of the second guide roller 6 and the rotation axes 51a, 52a, 53a, 54a, 55a of the rollers 51, 52, 53, 54, 55 are perpendicular to each other. In the example shown in the figure, the second guide roller 6 is arranged so that the optical fiber G2 is on the front side of the second guide roller 6 ( Figure 2 In addition, the second guide roller 6 may be configured such that the optical fiber G2 is on the inner side (front side) of the second guide roller 6. Figure 2 Thus, the second guide roller 6 can change the traveling direction of the optical fiber G2 to a direction different from that of the lower roller 5.

[0072] Next, refer to Figure 3 An embodiment of the lower roller 5 will be described. Figure 3 It is a cross-sectional view along the rotation axis of the direct lower roller 5 according to the embodiment. In addition, since the five rollers 51, 52, 53, 54, and 55 constituting the direct lower roller 5 have the same structure, only the roller 51 will be described in the following description. Figure 3 The roller 51 is Figure 2A cross-sectional view of the roller 51 taken along the line AA.

[0073] like Figure 3 As shown in FIG. 1 , the roller 51 includes: a rotation axis 51a provided at the center; an annular member 51b provided to surround the rotation axis 51a and configured to be rotatable relative to the rotation axis 51a; a running surface 51f, which is the outer peripheral surface of the annular member 51b, on which the optical fiber G2 runs; a bearing portion 51c provided around the rotation axis 51a; and a support portion 51d that supports the rotation axis 51a. The roller 51 of this embodiment is formed so that the running surface 51f on which the optical fiber G2 runs becomes flat when viewed from a direction perpendicular to the rotation axis 51a of the roller 51. The running surface 51f is formed along the direction of the rotation axis 51a when viewed from a direction perpendicular to the rotation axis 51a of the roller 51. Flanges 51e are formed on both sides of the running surface 51f to divide the width of the running surface 51f. The running surface 51f is formed as a flat running groove divided by the flanges 51e at both ends. The width B of the running surface 51f is greater than or equal to 2 mm and less than or equal to 10 mm. Figure 3 The example shown shows a cantilever beam type roller 51, but the present invention is not limited thereto, and for example, a double support type straight down roller may be used.

[0074] The running surface 51f is formed of a fluororesin capable of reducing friction, such as PTFE (tetrafluoroethylene resin), PFA (perfluoroalkoxy fluororesin), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), ETFE (ethylene-tetrafluoroethylene copolymer), etc.

[0075] In addition, “the running surface is formed of fluororesin” can include, for example, a case where the running surface is coated with fluororesin and a case where the annular member 51 b itself is formed of fluororesin.

[0076] like Figure 3 As shown, when the optical fiber G2 travels in the center of the width B direction of the traveling surface 51f, the direction of the rotating shaft 51a of the roller 51 is configured to be perpendicular (90 degrees) to the traveling direction of the optical fiber G2 on the traveling surface 51f.

[0077] A method for manufacturing the optical fiber G2 will be described.

[0078] First, a glass matrix G is put into the drawing furnace 2, and the glass matrix G is heated by the heating element 21 and stretched downward, thereby drawing a glass fiber G1 with a thin diameter.

[0079] Next, after the drawn glass fiber G1 is cooled by the cooling device 3 , the outer periphery of the glass fiber G1 is coated with resin by the coating unit 41 of the coating unit 4 , and the coated resin is cured by the curing unit 42 to form the resin-coated optical fiber G2 .

[0080] Next, the traveling direction of the optical fiber G2 coated with the resin is changed by the lower rollers 5 (rollers 51, 52, 53, 54, 55) provided directly below the drawing furnace 2. At this time, the rollers 51, 52, 53, 54, 55 guide the optical fiber G2 traveling on the traveling surface 51f in a state of contacting the traveling surface 51f at only one point when observing the cross section of the optical fiber G2 in contact with the rollers 51, 52, 53, 54, 55. At this time, each roller 51, 52, 53, 54, 55 rotates in the direction of arrow C (counterclockwise) shown in the figure along with the traveling of the optical fiber G2. The glass fiber G1 and the optical fiber G2 drawn from the glass mother material G are pulled by the capstan 7, so that the tension toward the rotating shafts 51a, 52a, 53a, 54a, 55a acts on the traveling surfaces 51f of the rollers 51, 52, 53, 54, 55 (also refer to Figure 3 ) on optical fiber G2.

[0081] Next, the optical fiber G2 whose traveling direction has been changed is guided toward the capstan 7 by the second guide roller 6 provided on the downstream side of the lower roller 5. At this time, the second guide roller 6 supports and guides the traveling optical fiber G2 from a direction different from the direction supported by the lower roller 5 (rollers 51, 52, 53, 54, 55).

[0082] Next, the guided optical fiber G2 is taken up by the capstan 7 and is wound around the winding bobbin 8 .

[0083] In addition, as shown in Patent Document 1, the purpose is to prevent the twisting of the optical fiber by holding the optical fiber at two points by sandwiching the optical fiber through the V-shaped groove. However, in recent years, the speed (line speed) of picking up the optical fiber has tended to increase, and the countermeasures for the twisting of the optical fiber are insufficient for the positive lower roller with a V-shaped running surface. For example, if the line speed of the optical fiber increases, the optical fiber may shake when picking it up.

[0084] For example, Figure 4 In the case where the outer peripheral surface of the annular member 151b and the running surface 151f on which the optical fiber G2 runs are V-shaped, if the optical fiber G2 shakes, the optical fiber G2 may contact only one surface of the V-shaped running surface 151f. At this time, since the capstan always applies a force toward the rotating shaft 151a of the V-shaped roller 151 to the optical fiber G2 running on the running surface 151f, the optical fiber G2 contacting one surface tries to be accommodated in the V-shaped groove 151g in a rolling manner. The inventors have found that in the above-mentioned case, the optical fiber G2 is easily twisted.

[0085] The greater the tension becomes, the greater the force acting on the optical fiber G2 running on the running surface 151f and toward the rotating shaft 151a of the V-shaped roller 151. Therefore, it is clear that the action of trying to be accommodated in the V-shaped groove 151g in a rolling manner becomes more significant, and the optical fiber G2 is easily twisted. If the portion of the optical fiber G2 running on the running surface 151f is twisted, the twist is transmitted not only to the optical fiber G2 of the running surface 151f, but also to the portion of the optical fiber G2 on the upstream side of the running surface 151f. Therefore, the optical fiber G2 fixed in an unexpected twisted state is sometimes manufactured.

[0086] In contrast, in the manufacturing device 1 of the present embodiment, when viewed from a direction orthogonal to the rotation axes 51a, 52a, 53a, 54a, and 55a, each running surface 51f on which the optical fiber G2 runs is flat, and its width B is greater than or equal to 2 mm and less than or equal to 10 mm. According to the above structure, each running surface 51f is flat, so the optical fiber G2 and the running surface 51f are in contact at one point. In addition, the width B of the running surface 51f is ensured to be greater than or equal to 2 mm, so even if a flange 51e is provided outside the width B of the running surface 51f, the running optical fiber G2 is not likely to contact the flange 51e. In addition, since the width B is less than or equal to 10 mm, it is possible to suppress the lower roller 5 (rollers 51, 52, 53, 54, and 55) from becoming excessively heavy, and thus it is possible to suppress the running resistance of the lower roller 5. Although the force toward the rotation axes 51a, 52a, 53a, 54a, and 55a always acts on the optical fiber G2 traveling on the traveling surface 51f, by making the traveling surface 51f flat, the optical fiber G2 is less likely to roll on the traveling surface 51f than when the traveling surface 151f of the V-shaped roller 151 is made V-shaped. Thus, the optical fiber G2 with less twist can be manufactured.

[0087] In the manufacturing device 1 of the present embodiment, when the optical fiber G2 travels in the center of the running surface 51f of the rollers 51, 52, 53, 54, 55, the directions of the rotation axes 51a, 52a, 53a, 54a, 55a of the rollers 51, 52, 53, 54, 55 are perpendicular to the running direction of the optical fiber G2 on the running surface 51f. At this time, if the optical fiber G2 travels in the center of the running surface 51f, the optical fiber G2 is not easy to roll in the width direction of the running surface. Therefore, by setting the above structure, it is possible to suppress the twisting of the optical fiber G2.

[0088] In the manufacturing device 1 of this embodiment, the running surfaces 51f of the rollers 51, 52, 53, 54, and 55 are formed of fluororesin. The friction force of the running surface 51f can be reduced, so the optical fiber G2 is easy to slide when a force is applied to the width direction of the running surface 51f. As a result, the rolling and twisting of the optical fiber G2 due to the friction force between the optical fiber G2 and the running surface 51f can be suppressed.

[0089] In the manufacturing device 1 of the present embodiment, the lower roller 5 is composed of a plurality of rollers 51, 52, 53, 54, 55, and is configured so that when viewed from the direction of the rotating axes 51a, 52a, 53a, 54a, 55a of the rollers 51, 52, 53, 54, 55, the rotating axes 51a, 52a, 53a, 54a, 55a of the rollers 51, 52, 53, 54, 55 are arranged in an arc shape.

[0090] The running direction of the optical fiber G2 is sequentially changed by the plurality of rollers 51, 52, 53, 54, and 55, so that the change angle of the running direction changed by one positive lower roller can be reduced, and thus the contact length of one positive lower roller and the optical fiber G2 can be shortened. At this time, the friction force generated between one positive lower roller and the optical fiber G2 can be reduced, and thus the twisting of the optical fiber G2 caused by the friction force can be suppressed.

[0091] Furthermore, by reducing the change angle of the running direction changed by one positive lower roller, the time and distance that the optical fiber G2 contacts the rollers 51, 52, 53, 54, 55 can be shortened, so when the optical fiber G2 rolls on a plurality of running surfaces of the rollers 51, 52, 53, 54, 55 including the running surface 51f, the twist amount of each roller 51, 52, 53, 54, 55 becomes smaller. As a result, the twist amount transmitted to the upstream side and the distance over which the twist is transmitted to the upstream side can be reduced.

[0092] Furthermore, according to the optical fiber manufacturing method of the present embodiment, the optical fiber G2 contacts only one point of each of the rollers 51, 52, 53, 54, and 55 constituting the bottom roller 5. Therefore, compared with a bottom roller that is guided by contacting at two points, such as a bottom roller having a V-shaped running surface, the optical fiber G2 is less likely to roll on the running surface.

[0093] The bottom roller 5 may be composed of only one roller, but as in the present embodiment, it is preferably composed of a plurality of rollers 51, 52, 53, 54, and 55. By using a plurality of bottom rollers, the diameter of each bottom roller can be reduced compared to using a single bottom roller.

[0094] At this time, the total length of the contact portion between each running surface 51f and the optical fiber G2 (contact length) is shorter than the length of the contact portion between the running surface of a single positive lower roller and the optical fiber G2 running on the running surface. By reducing the contact length of the entire positive lower roller 5 with the optical fiber G2, the frictional force exerted by the running surface 51f on the optical fiber is reduced, so it is easy to suppress the twisting of the optical fiber due to the frictional force.

[0095] In addition, the total contact angle of the roller is preferably 90 degrees or less. "The contact angle of the roller" refers to the central angle of the roller corresponding to the arc length of the contact between the roller and the optical fiber. The total contact angle with the optical fiber is set to 90 degrees or less, thereby reducing the contact length with the optical fiber, thereby suppressing the friction force generated between the running surface 51f and the optical fiber G2 and suppressing the twisting of the optical fiber G2.

[0096] The manufacturing apparatus 1 of this embodiment is provided with a second guide roller 6 on which the optical fiber G2 travels after the positive lower roller 5, on the downstream side of the positive lower roller 5, and the rotation axis 6a of the second guide roller 6 is perpendicular to the rotation axes 51a, 52a, 53a, 54a, 55a of the positive lower roller 5 (rollers 51, 52, 53, 54, 55). At this time, the direction in which the positive lower roller 5 (rollers 51, 52, 53, 54, 55) supports the optical fiber G2 is different from the direction in which the second guide roller 6 supports the optical fiber G2. Therefore, when the optical fiber G2 travels on the travel surface 51f of the positive lower roller 5 (rollers 51, 52, 53, 54, 55), it is not easy to roll in the width direction of the travel surface 51f, so it is possible to suppress the optical fiber G2 from being twisted.

[0097] The second guide roller 6 is preferably arranged so that the optical fiber G2 traveling from the positive lower roller 5 to the second guide roller 6 is at right angles to the rotation axis 6a of the second guide roller 6. In this case, the contact length between the second guide roller 6 and the optical fiber G2 can be reduced, thereby suppressing the twisting of the optical fiber G2.

[0098] (First Modification of the Positive Lower Roller)

[0099] Next, refer to Figure 5 and Figure 6 , a first modification example of the lower roller 5 is described. Figure 5 2 is a cross-sectional view along the rotation axis of the positive lower roller 5 involved in the first modified example. In addition, the five rollers 251, 252, 253, 254, and 255 (also refer to FIG. 2 ) constituting the positive lower roller 5 of the first modified example Figure 3 ) have the same structure, so only roller 251 is described in the following description. Figure 5 The roller 251 is Figure 2 A cross-sectional view of roller 251 taken along line AA.

[0100] like Figure 5As shown, the roller 251 has: a rotating shaft 251a, which is provided at the center; an annular member 251b, which is provided to surround the rotating shaft 251a and is rotatable relative to the rotating shaft 251a; a running surface 251f, which is the outer peripheral surface of the annular member 251b, for the optical fiber G2 to run; a bearing portion 251c, which is provided around the rotating shaft 251a; and a support portion 251d, which supports the rotating shaft 251a. The rotating shaft 251a of the roller 251 is supported by the support portion 251d via an elastic member (such as rubber, etc.) 251g. The elastic member 251g is provided between the outer periphery of the two ends of the rotating shaft 251a and the inner periphery of the support hole provided in the support portion 251d. The roller 251 is a double-support type roller.

[0101] In addition, Figure 3 The similarities of the roller 51 are as follows: when viewed from a direction orthogonal to the rotation axis 251a of the roller 251, the traveling surface 251f on which the optical fiber G2 travels is formed to be flat; flanges 251e are formed on both sides of the traveling surface 251f, the width B of the traveling surface 251f is greater than 2 mm and less than 10 mm, etc.

[0102] For example, Figure 6 As shown in FIG. 1 , when the optical fiber G2 travels at a position deviated from the central portion of the running surface 251f in the direction of the arrow D, the optical fiber G2 travels in a slightly different direction compared to the case where the optical fiber G2 travels in the central portion of the running surface 251f. In contrast, the rotating shaft 251a of the roller 251 of the first modified example is supported by the support portion 251d via the elastic member 251g, and can thus swing relative to the support portion 251d to a certain extent. Therefore, even when the optical fiber G2 travels at a position other than the central portion of the running surface 251f, the orientation of the roller 251 can be adjusted so that the direction of the rotating shaft 251a becomes perpendicular to the running direction of the optical fiber G2. As a result, the optical fiber G2 is not easily rolled in the width direction of the running surface 251f, and thus the twisting of the optical fiber G2 can be suppressed.

[0103] (Second modification of the positive lower roller)

[0104] Next, refer to Figure 7 and Figure 8 , a second modification example of the lower roller 5 will be described. Figure 7 2 is a cross-sectional view along the rotation axis of the positive lower roller 5 involved in the second modified example. In addition, the five rollers 351, 352, 353, 354, and 355 (also refer to FIG. 2 ) constituting the positive lower roller 5 of the second modified example Figure 3 ) have the same structure, so only roller 351 is described in the following description. Figure 7 The roller 351 is Figure 2 A cross-sectional view of roller 351 at line AA.

[0105] like Figure 7 As shown in FIG. 1 , the roller 351 includes: a rotation axis 351a provided at the center; an annular member 351b provided to surround the rotation axis 351a and configured to be rotatable relative to the rotation axis 351a; a running surface 351f, which is the outer peripheral surface of the annular member 351b, on which the optical fiber G2 runs; a bearing portion 351c provided around the rotation axis 351a; and a support portion 351d that supports the rotation axis 351a. When viewed from a direction orthogonal to the rotation axis 351a of the roller 351, the running surface 351f of the roller 351 is formed into a convex shape in which the central portion in the width direction is slightly convex compared to other portions. For example, the running surface 351f of the roller 351 is formed into an arc-shaped convex shape. The running surface 351f of the roller 351 is formed so that the curvature radius r becomes the running distance R of the optical fiber G2 from the point where the optical fiber G2 separates from the running surface 351f to the point where the optical fiber G2 contacts the capstan 7 (see Figure 1 )above.

[0106] In addition, rollers 352, 353, 354, and 355 may have the same curvature radius r as roller 351, or rollers having different curvature radii may be used. When rollers having different curvature radii are used, for example, the curvature radius of each of rollers 352, 353, 354, and 355 may be formed to be greater than the travel distance of optical fiber G2 from the point where optical fiber G2 separates from the travel surface 351f to the point where optical fiber G2 contacts the capstan 7.

[0107] In addition, Figure 3 The roller 51 of FIG. 51 is similar in that flanges 351 e are formed on both sides of a running surface 351 f of the roller 351 , and a width B of the running surface 351 f is greater than or equal to 2 mm and less than or equal to 10 mm.

[0108] For example, Figure 8 As shown in FIG. 1 , even if the traveling position of the optical fiber G2 deviates from the central portion of the traveling surface 351f in the direction of the arrow E and the traveling direction of the optical fiber G2 is inclined, since the traveling surface 351f is an arc-shaped convex shape, there will be a traveling surface 351f that is perpendicular to the traveling direction of the optical fiber G2 at the deviated position. As a result, the optical fiber G2 is not easy to roll in the width direction of the traveling surface 351f. In addition, in order to make the optical fiber G2 not easy to roll on the traveling surface 351f, it is preferred that the curvature radius r of the traveling surface 351f is set to be greater than the traveling distance R of the optical fiber G2 from the point where the optical fiber G2 separates from the traveling surface 351f to the point where the optical fiber G2 contacts the capstan 7.

[0109] The present invention has been described in detail and with reference to specific embodiments, but it is obvious to those skilled in the art that various changes or modifications can be made without departing from the spirit and scope of the present invention. In addition, the number, position, shape, etc. of the structural components described above are not limited to the above embodiments, and can be changed to the number, position, shape, etc. suitable for implementing the present invention.

[0110] For example, in this embodiment, the example that the positive lower roller is composed of 5 rollers is given for explanation, but the number of rollers constituting the positive lower roller is not limited to the example of this embodiment. For example, the positive lower roller may be composed of less than 5 rollers, or may be composed of more than 5 rollers.

[0111] In addition, the running surface of the second guide roller may be flat, convex, or concave (including V-shaped).

[0112] Description of the label

[0113] 1 Optical fiber manufacturing device

[0114] 2 Wire drawing furnace

[0115] 3 Cooling device

[0116] 4. Coating unit

[0117] 5 positive lower roller

[0118] 6 Second guide roller

[0119] 7 Winch

[0120] 8 Winding spools

[0121] 21 Heating element

[0122] 41 Coating Department

[0123] 42 Curing Department

[0124] Roller 51, 52, 53, 54, 55, 251, 252, 253, 254, 255, 351, 352, 353, 354, 355

[0125] 6a, 51a, 52a, 53a, 54a, 55a, 151a, 251a, 351a rotation axis

[0126] 51b, 151b, 251b, 351b annular parts

[0127] 51c, 251c, 351c bearings

[0128] 51d, 251d, 351d support part

[0129] 51e, 251e, 351e flange

[0130] 6f, 51f, 151f, 251f, 351f running surface

[0131] 151 V-shaped roller

[0132] 151g V-groove

[0133] 251g elastic parts

[0134] G Glass base material

[0135] G1 Fiberglass

[0136] G2 Fiber

Claims

1. An optical fiber manufacturing device, comprising: A drawing furnace, which melts the glass matrix and draws the glass fiber into a wire; A coating unit, which coats the glass fiber with a resin layer to form an optical fiber; A lower roller, which is arranged directly below the drawing furnace and changes the traveling direction of the optical fiber; and a capstan which picks up the optical fiber, If the positive lower roller is viewed from a direction orthogonal to the rotation axis of the positive lower roller, the running surface of the positive lower roller on which the optical fiber runs is flat or convex. The width of the running surface is greater than or equal to 2 mm and less than or equal to 10 mm.

2. The optical fiber manufacturing device according to claim 1, wherein: When the optical fiber runs on the center portion of the running surface, the direction of the rotation axis of the positive lower roller is perpendicular to the running direction of the optical fiber on the running surface.

3. The optical fiber manufacturing device according to claim 1 or 2, wherein: The rotation axis of the positive lower roller is supported by an elastic member.

4. The optical fiber manufacturing device according to claim 1 or 2, wherein: The running surface of the positive lower roller is convex when the positive lower roller is viewed from a direction orthogonal to the rotation axis of the positive lower roller. The curvature radius of the running surface of the positive lower roller is greater than or equal to a running distance of the optical fiber from a point where the optical fiber separates from the running surface to a point where the optical fiber contacts the capstan.

5. The optical fiber manufacturing device according to claim 1 or 2, wherein: The running surface is formed of fluororesin.

6. The optical fiber manufacturing device according to claim 1 or 2, wherein: The positive lower roller is composed of a plurality of rollers. The plurality of rollers are arranged such that the rotation axes of the plurality of rollers are arranged in an arc shape when viewed from the rotation axis direction of the rollers.

7. The optical fiber manufacturing device according to claim 1 or 2, wherein: A second guide roller is provided on the downstream side of the positive lower roller, with which the optical fiber contacts after the positive lower roller. The second guide roller is disposed so that the rotation axis of the second guide roller and the rotation axis of the lower roller are perpendicular to each other.

8. A method for manufacturing an optical fiber, comprising coating a glass fiber drawn from a glass mother material in a drawing furnace with a resin to obtain an optical fiber, In the method for manufacturing the optical fiber, A positive lower roller disposed just below the drawing furnace to change the traveling direction of the optical fiber guides the optical fiber so that the optical fiber contacts only one point when observing a cross section of the optical fiber in contact with the positive lower roller.

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