JP2005289764A - Method of manufacturing optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture an optical fiber having an excellent appearance by preventing the ununiformity of coating diameter due to the vibration at the taking-in time. <P>SOLUTION: A glass fiber G1 drawn from an optical fiber preform G heated in a heating furnace 2 is coated with a resin by a resin coating dies composed of a primary dies 8 and a secondary dies 9 to obtain the optical fiber G2, then the optical fiber G2 is taken in by a capstan 16 through a direct lower roller 11. A flat roller 13 having a cylindrical peripheral surface parallel to the axial direction is made in contact with the optical fiber G2, thereby suppressing the fine vibration occurring on the optical fiber G2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical fiber manufacturing method for manufacturing an optical fiber by drawing an optical fiber preform.

Generally, when manufacturing an optical fiber, first, an optical fiber preform manufactured from a material such as quartz is supplied to a heating furnace by a feeding device, and the tip portion is heated and softened in the heating furnace, and is drawn out to a small diameter. To make a glass fiber.
Next, the resin is coated on the outer periphery by passing the thinned glass fiber through a resin coating die for coating the ultraviolet curable resin and an ultraviolet irradiation device for irradiating and curing the applied ultraviolet curable resin. Optical fiber.

  The optical fiber manufactured in this way is guided by a direct lower roller provided at a position in a vertically downward direction with respect to the optical fiber preform, and a plurality of introduction rollers, and then drawn downstream by a capstan. It is wound on a winding bobbin.

  In addition, by keeping the resin pressure supplied to the resin coating die constant, it is possible to suppress the introduction of bubbles into the resin due to fluctuations in the resin pressure, and to maintain the outer diameter of the optical fiber constant and eliminate the appearance defects. It is known (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 7-15744

  By the way, the direct roller and the introduction roller, which are guide rollers for guiding the resin-coated optical fiber to the capstan, rotate while holding the optical fiber in a V-groove formed in the periphery. The sent optical fiber may move in the radial direction along the inner wall of the V-groove by the roller directly below and the introduction roller, and may generate minute vibrations. When the minute vibration of the optical fiber is transmitted to the upstream resin application die, the resin flow is disturbed and the resin is not uniformly adhered to the glass fiber, and the coating of the optical fiber is inconsistent (waved). The coating diameter is disturbed, resulting in poor appearance.

  Here, in the above-described conventional technique for keeping the resin pressure supplied to the resin coating die constant, it is possible to prevent the mixing of bubbles in a long distance range and keep the outer diameter constant. Control that keeps the resin pressure constant cannot follow the minute vibration that occurs, and appearance defects due to minute vibration of the optical fiber cannot be prevented.

  An object of the present invention is to provide a method of manufacturing an optical fiber that can prevent the disturbance of the coating diameter due to vibration during take-up and can manufacture an optical fiber having a good appearance.

  An optical fiber manufacturing method of the present invention that can achieve the above object is an optical fiber manufacturing method in which a glass fiber drawn from an optical fiber preform is coated with a resin with a resin coating die to form an optical fiber. The optical fiber preform, the resin-applying die, and the optical fiber immediately after being coated with the resin by the resin-applying die are positioned downstream of a roller directly below the first optical fiber so that the optical fiber is aligned. The roller in which the traveling direction of the optical fiber is changed to one direction and the rotating shaft does not move is a flat roller in which the surface in contact with the optical fiber constitutes a cylindrical circumferential surface parallel to the rotating shaft of the roller. Yes.

  Further, it is preferable that the optical fiber is in contact with the optical roller between the direct lower roller and the take-off means for taking the optical fiber, and the roller that changes the traveling direction of the optical fiber in one direction is the flat roller. .

According to the optical fiber manufacturing method of the present invention, the roller that first contacts the optical fiber downstream of the direct roller is a flat roller having a cylindrical circumferential surface parallel to the rotation axis direction. The movement in the radial direction can be reduced.
Thereby, the transmission of vibration from the downstream side of the optical fiber to the resin coating die can be prevented, and the occurrence of turbulence of the resin flow in the resin coating die can be eliminated. That is, it is possible to manufacture an optical fiber having a good appearance in which the resin is uniformly attached to the glass fiber and the coating diameter is prevented from being disturbed by vibration.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a manufacturing apparatus to which an optical fiber manufacturing method according to the present embodiment can be applied, and FIG. 2 is a side view and a front view of a flat roller provided in the manufacturing apparatus.

As shown in FIG. 1, the optical fiber manufacturing apparatus 1 includes a heating furnace 2 that heats the optical fiber preform G on the upstream side of the optical fiber travel line. The heating furnace 2 includes a cylindrical furnace core tube 4 to which an optical fiber preform G is supplied, and a heating element 3 that is a heater surrounding the furnace core tube 4. By causing the heating element 3 to generate heat, the temperature of the core tube 4 rises, and a heating region is formed in the space inside. A heating area | region here is an area | region which becomes the temperature which can be drawn by softening glass, for example, is an area | region which is 1800 degreeC or more.
Further, the heating furnace 2 is provided with a gas supply unit 31, and a cooling gas such as helium or nitrogen is supplied from the gas supply unit 31 to the heating region.

The upper part of the optical fiber preform G is held by the feeding means 5 and fed into the heating furnace 2 so that the lower end portion is positioned in the heating region inside the furnace core tube 4. Thus, the lower end side of the optical fiber preform G supplied into the heating furnace 2 is heated and softened in the heating region, and is drawn downward to reduce the diameter, thereby forming the glass fiber G1. .
On the downstream side of the heating furnace 2, for example, a cooling device 6 using a cooling solvent such as helium gas is provided, and the glass fiber G1 immediately after leaving the heating furnace 2 rapidly rises from several hundred degrees C to near room temperature. To be cooled.

Further, on the downstream side of the cooling device 6, for example, a laser beam type outer diameter measuring device 7 is provided, and the outer diameter of the glass fiber G 1 exiting the cooling device 6 is reduced by the outer diameter measuring device 7. Measured.
On the downstream side of the outer diameter measuring instrument 7, a primary die 8 and a secondary die 9 for applying an ultraviolet curable resin to the glass fiber G1 are sequentially provided. Further, on the downstream side of the primary die 8 and the secondary die 9, there is provided an ultraviolet irradiation device 10 for irradiating the ultraviolet curable resin with ultraviolet rays to be cured.

As a result, the glass fiber G1 passes through the primary die 8 and the secondary die 9 and the ultraviolet irradiation device 10, so that the primary resin and the secondary resin are applied to the outer peripheral side thereof to form a two-layer coating layer. G2.
The optical fiber G2 has an outer diameter of about 200 μm due to the primary resin coating layer and an outer diameter of about 250 μm due to the secondary resin coating layer.

  Thereafter, the direction of the travel line is changed by the immediately lower roller 11 provided on the downstream side of the ultraviolet irradiation device 10, and the optical fiber G <b> 2 is sent out to the plurality of introduction rollers 12. The direct roller 11 is arranged so that the optical fiber preform G, the primary die 8, the secondary die 9, and the optical fiber G2 immediately after being coated with the resin are in a straight line, and guides the optical fiber to the downstream side. Is. The directly below roller 11 and the introduction roller 12 are rollers having a V groove, and guide the optical fiber G2 through the V groove. Thereafter, the optical fiber G2 guided by the introduction roller 12 is taken up by a capstan (take-out means) 16 and a predetermined tension is applied thereto.

Further, a flat roller 13 is provided between the direct roller 11 and the capstan 16 and rotates in contact with the optical fiber G2 so as to slightly bend the travel line. Preferably, the flat roller 13 may be provided immediately downstream of the direct roller 11. As shown in FIG. 2, the flat roller 13 has flange portions 13a formed on both sides thereof, and has a cylindrical peripheral surface 13b that is flat in the direction of its own rotation axis. Further, the rotation axis direction of the flat roller 13 is substantially along the rotation axis direction of the directly below roller 11, and the width direction of the peripheral surface 13 b coincides with the direction orthogonal to the radial direction of the immediately below roller 11. Are arranged as follows. Further, the flat roller 13 is disposed at a fixed position so that the rotation shaft does not move, stably contacts the optical fiber G2, and guides the traveling direction of the optical fiber G2 by changing it in an arbitrary direction. .
In addition, as this flat roller 13, the diameter of the surrounding surface 13b is 100-150 mm, and the width dimension of the surrounding surface 13b is about 50-100 mm.

  The introduction roller 12 with which the optical fiber G2 contacts between the directly below roller 11 and the capstan 16 is usually a V-groove roller as described above. It is also possible to use a roller that has a flat cylindrical peripheral surface and changes the traveling direction of the optical fiber G2 in one direction.

The capstan 16 includes a capstan belt 18 wound around a plurality of rollers 17 and a capstan roller 19 to which the capstan belt 18 is closely attached. The capstan belt 18, the capstan roller 19, The optical fiber G2 is sandwiched between and pulled.
The optical fiber G <b> 2 taken up by the capstan 16 is sent to the take-up bobbin 24 via the guide roller 21 and the dancer rollers 22 and 23, and is taken up by the take-up bobbin 24.

Next, the case where the optical fiber G2 is manufactured using the above-described optical fiber manufacturing apparatus 1 will be described.
First, the optical fiber preform G is put into the heating furnace 2, heated by the heating element 3, and drawn downward to obtain a glass fiber G 1 having a reduced diameter.
Next, the outer periphery of the glass fiber G1 is covered with an ultraviolet curable resin by the primary die 8 and the secondary die 9, and further, the ultraviolet curable resin is irradiated with ultraviolet rays and cured by the ultraviolet irradiation device 10, whereby two layers of resin are formed. Let it be a coated optical fiber G2.

  Thereafter, the optical fiber G2 is sent out to a plurality of introduction rollers 12 via the directly below rollers 11, wound around these introduction rollers 12, and then pulled in by a capstan 16 to apply a predetermined tension, and sent to the take-up bobbin 24. Then, the winding bobbin 24 is wound.

  Here, in the direct roller 11 and the introduction roller 12 that guide the optical fiber G2 to the capstan 16, the optical fiber G2 that travels at a high speed has a diameter along the slope in the V groove of the direct roller 11 and the introduction roller 12. For example, a minute vibration of about 1.5 Hz may be generated by changing in the direction. However, the minute vibration of the optical fiber G2 is suppressed by the flat peripheral surface 13b of the flat roller 13 provided between the direct roller 11 and the introduction roller 12. At that time, the optical fiber G2 may slide on the peripheral surface 13b in the axial direction of the flat roller 13. Since the movement of the optical fiber G2 in the axial direction of the flat roller 13 is restricted and restrained by the V groove of the direct roller 11, vibration of the optical fiber G2 on the upstream side of the direct roller 11 is reduced.

  In addition, when the introduction roller 12 is a roller that has a flat cylindrical peripheral surface in the direction of its own rotation axis and changes the traveling direction of the optical fiber G2 in one direction, the minute vibration of the optical fiber G2 is further reduced. Can be made.

As described above, according to the method of manufacturing an optical fiber according to the above-described embodiment, the optical fiber G2 is brought into contact with the flat roller 13 having the flat cylindrical peripheral surface 13b when the resin is coated and taken out. Micro vibrations generated in G2 can be reduced.
Thereby, the transmission of vibrations to the resin coating die composed of the primary die 8 and the secondary die 9 can be prevented, and the occurrence of turbulence of the resin flow in the resin coating die can be eliminated. Accordingly, it is possible to manufacture an optical fiber having a good appearance in which the resin is uniformly attached to the glass fiber G1 and the disturbance of the coating diameter due to vibration is prevented.

  Appearance abnormality in the case where the optical fiber is manufactured while providing the flat roller of the above embodiment and preventing the minute vibration of the optical fiber (Example) and in the case where the optical fiber is manufactured without providing the flat roller (Comparative Example) The incidence of was investigated. The occurrence rate of the appearance abnormality was determined by investigating a predetermined number of bobbins, and the ratio of bobbins in which the appearance abnormality of the optical fiber was found in the investigated bobbins. The results are shown in Table 1.

As can be seen from Table 1, in the case where the optical fiber was manufactured while suppressing the vibration of the optical fiber by the flat roller, the appearance abnormality occurrence rate was 0%, whereas the light was not provided with the flat roller. In the case of the comparative example in which the fiber was manufactured, the appearance abnormality occurrence rate was 20%.
For this reason, by bringing the flat roller into contact with the optical fiber, the minute vibration generated in the optical fiber is surely suppressed by the flat roller to suppress the disturbance of the coating diameter of the optical fiber, and a good optical fiber having no appearance defect can be obtained. It was found that it can be manufactured.

It is a schematic block diagram of the manufacturing apparatus which can apply the manufacturing method of the optical fiber which concerns on embodiment of this invention. It is the side view and front view of the flat roller provided in the manufacturing apparatus.

Explanation of symbols

8 Primary dies (resin coating dies)
9 Secondary dies (resins for resin application)
11 Directly below roller 13 Flat roller 13b Cylindrical peripheral surface 16 Capstan (take-off means)
G Optical fiber preform G1 Glass fiber G2 Optical fiber

Claims (2)

A method for producing an optical fiber, in which a glass fiber drawn from an optical fiber preform is coated with a resin by a resin coating die to form an optical fiber,
The optical fiber preform, the resin-applying die, and the optical fiber immediately after the resin is coated with the resin-applying die are arranged downstream of a roller directly below the optical fiber so that the optical fiber is aligned. The roller in which the traveling direction of the fiber is changed to one direction and the rotating shaft does not move is a flat roller in which the surface in contact with the optical fiber constitutes a cylindrical circumferential surface parallel to the rotating shaft of the roller. An optical fiber manufacturing method.   The roller that is in contact with the optical fiber between the roller immediately below and the take-off means for taking up the optical fiber, and the roller that changes the traveling direction of the optical fiber in one direction is the flat roller. The manufacturing method of the optical fiber of Claim 1.