JP3777627B2 - Glass fiber manufacturing method and manufacturing apparatus - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a technique for manufacturing a glass fiber such as an optical fiber while adjusting its twist.
[0002]
[Prior art]
Conventionally, a polarization-maintaining optical fiber is known as one of glass fibers. This optical fiber is sometimes used in a state of being wound around a small-diameter reel as one of optical fiber type gyroscope components. At that time, by winding with the birefringent main axes aligned, deterioration of the polarization characteristics in the coil state can be prevented. An example of this type of optical fiber is one having a non-circular cross section as disclosed in Japanese Patent Laid-Open No. 60-108807. This is caused by bending, etc., by making the birefringent main axis direction distinguishable from the appearance by making it non-circular in cross section, and winding the relationship between the bending direction of the optical fiber and the birefringent main axis constant. This is to prevent deterioration of the polarization characteristics. In such an optical fiber, the optical fiber base material having a non-circular cross section is drawn by melting in a heating furnace, and the resulting bare optical fiber is passed through a resin coating apparatus, via a guide roller or the like. Manufactured by winding onto a bobbin.
[0003]
However, for example, when the rotation axis of the guide roller directly under the heating furnace and the direction in which the drawn optical fiber travels are not perpendicular, a torque that twists the optical fiber around the axis is being produced. To join. As a result, the optical fiber is twisted about its axis. In this case, it becomes very difficult to wind in a coil shape with the birefringence main axes aligned as described above, and the effect of making the cross section non-circular will not be sufficiently exhibited.
[0004]
On the other hand, as shown in British Patent GB2101762A or Japanese Patent Laid-Open No. 6-171970, the optical fiber is intentionally twisted by rotating the optical fiber preform or by swinging the guide roller of the manufacturing apparatus. In addition, a method for reducing the polarization mode dispersion is also conventionally known. However, when twisting occurs in the direction opposite to the intended direction or when a sufficient amount of twisting cannot be obtained, the original effect is not sufficiently exhibited.
[0005]
Therefore, a technique for measuring the twist applied during the production of the glass fiber and adjusting the amount and direction of the twist based on the measurement result to produce the glass fiber is important.
[0006]
Conventionally, glass fibers are inspected after manufacturing is completed, and if twist is found, the amount of twist and the direction of twist are obtained, and the production equipment is adjusted based on this data, and then the glass fiber is remanufactured. Yes. Glass fiber inspection is performed by measuring optical properties and observing the geometric structure of the glass fiber with a microscope.
[0007]
[Problems to be solved by the invention]
However, in the conventional method, since the twist is measured after the production of the glass fiber, if the twist is discovered, the glass fiber produced so far is wasted, which causes a reduction in the production yield. It was. In addition, it may be necessary to repeat the production many times before obtaining the desired glass fiber, and it has not always been easy to obtain the desired glass fiber.
[0008]
This invention is made | formed in view of the above, and aims at providing the method and apparatus which can manufacture a desired glass fiber reliably and easily.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the glass fiber manufacturing method of the present invention is a glass fiber having a cross section of substantially the same shape along the longitudinal direction, and has a width measured from a direction substantially perpendicular to the longitudinal direction. This is a method for manufacturing a material that changes according to the measurement direction, and measures the width of the glass fiber that moves in the longitudinal direction during drawing, and the change in the measured value. A second step of obtaining the twist information of the glass fiber based on the second step, and a third step of adjusting the twist of the glass fiber based on the twist information.
[0010]
The first step is a step of heating and melting and drawing a columnar glass base material whose width measured from a direction substantially perpendicular to the axial direction changes according to the measurement direction. The step may be a step of rotating the glass base material around its axis at a rotation speed and a rotation direction according to the twist information.
[0011]
The third step is a step of guiding the glass fiber with a swinging guide roller having a roller surface in contact with the glass fiber and swinging the guide roller at a swinging speed according to torsion information. Also good.
[0012]
Next, the glass fiber manufacturing apparatus of the present invention has a glass fiber having a cross section of substantially the same shape along the longitudinal direction, and a width measured from a direction substantially perpendicular to the longitudinal direction is changed according to the measurement direction. An apparatus for producing molten glass by drawing, a heating means for heating and melting a columnar glass base material, and a measuring means for measuring the width of a glass fiber drawn from the glass base material and moving in the longitudinal direction A twist imparting means for causing the glass fiber to twist, a control means for obtaining twist information of the glass fiber based on a change in a measurement value output from the measurement means, and controlling the twist imparting means based on the twist information; Winding means for winding the glass fiber measured by the measuring means.
[0013]
In the manufacturing apparatus of the present invention, the measuring means measures the width of the glass fiber from the first and second measuring directions, and the control means compares the change in the measured value measured from each measuring direction. An apparatus for obtaining the twist amount and twist direction of the glass fiber may be used.
[0014]
Further, in the manufacturing apparatus of the present invention, the twist imparting means is a base material rotating means for rotating the glass base material around its axis, and the control means controls the base material rotating means so that the twist information is obtained. An apparatus that rotates the glass base material at the rotation speed and the rotation direction may be used.
[0015]
In the manufacturing apparatus of the present invention, the twist imparting means is a guide roller that swings with a roller surface that contacts the glass fiber, and the control means swings the guide roller at a swing speed corresponding to the twist information. It may be a device.
[0016]
[Action]
The glass fiber produced by the production method of the present invention has a cross section having substantially the same shape along the longitudinal direction, and the width measured from the direction substantially perpendicular to the longitudinal direction changes according to the measurement direction. For this reason, if the measurement direction is fixed in one direction, when the glass fiber moving in the longitudinal direction is twisted, the measured value of the width changes with time. Since the change in the measured value of the width corresponds to the twist of the glass fiber, information on the twist can be obtained by examining the change in the measured value.
[0017]
In the present invention, the drawing of the glass fiber is continuously performed while adjusting the twist generated in the glass fiber based on the twist information obtained during the production of the glass fiber. It is possible to reliably and easily produce a desired glass fiber such as a glass fiber having no twist.
[0018]
A glass having a cross-sectional shape substantially similar to the cross-sectional shape of this glass base material when a columnar glass base material whose width measured from a direction substantially perpendicular to the axial direction changes according to the measurement direction is drawn. Fiber, that is, a glass fiber in which the width measured from a direction substantially perpendicular to the longitudinal direction changes according to the measurement direction is obtained. When the glass base material is rotated around its axis during drawing of the glass fiber, a twist corresponding to the rotation of the base material is imparted to the glass fiber. By adjusting the rotation speed and direction of the glass base material based on the twist information obtained in the second step, the twist amount and twist direction of the glass fiber drawn from the glass base material can be adjusted.
[0019]
Further, when the guide roller is swung while drawing the glass fiber, the glass fiber rotates on the roller surface, so that the glass fiber is twisted. Further, if the guide roller is kept tilted at a substantially constant angle, a certain twist is imparted. If the swing speed of the guide roller is adjusted based on the twist information obtained in the second step, the twist amount and twist direction of the glass fiber can be adjusted.
[0020]
Next, according to the glass fiber manufacturing apparatus of the present invention, even when the twist of the glass fiber at the start of drawing is different from the desired one, the control means controls the twist imparting means based on the twist information, Since the twist is adjusted during drawing, the desired glass fiber such as a glass fiber to which a desired twist is imparted and a glass fiber having no twist can be reliably and easily manufactured.
[0021]
When the measuring means measures the width of the glass fiber from the first and second measuring directions, the measured values measured from the measuring directions are input to the control means, respectively. By comparing the time changes of the two measured values, not only the twist amount but also the twist direction can be obtained, and the control means accurately adjusts the twist of the glass fiber based on these information.
[0022]
In the manufacturing apparatus of the present invention, when the control means rotates the glass base material, the glass fiber drawn from the glass base material is twisted according to the rotation of the glass base material. The amount and direction of twist generated in the glass fiber depends on the rotation speed and direction of the glass base material, but the control means adjusts the rotation speed and direction of the glass base material based on the twist information. The resulting twist is adjusted appropriately.
[0023]
Further, in the manufacturing apparatus of the present invention, which includes a guide roller, when the guide roller is swung, the glass fiber is sent to the winding means while rotating on the roller surface, so that it is drawn from the glass base material. Twisting is imparted to the glass fiber. Further, if the guide roller is kept tilted at a substantially constant angle, a certain twist is imparted. Since the control means adjusts the swing of the guide roller based on the twist information, the twist applied to the glass fiber is appropriately adjusted.
[0024]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the dimensional ratios in the drawings do not necessarily match those described.
[0025]
Example 1
In this embodiment, an optical fiber having an elliptical cross section is manufactured as the glass fiber. FIG. 1 is an overall configuration diagram showing a glass fiber manufacturing apparatus according to the present embodiment. The manufacturing apparatus includes a motor 12, a heating furnace 14, outer diameter measuring devices 20 and 22, a control device 24, guide rollers 40, 42 and 44, and a take-up bobbin 50, and further, coating dies 30 and 34, and a UV lamp. 32 and 36 are provided.
[0026]
2A to 2D are views showing the cross-sectional shapes of the glass base material 10 and the drawn optical fiber, and FIG. 2A is taken along the line AA ′ of FIG. 2B is a cross-sectional view taken along the line BB ′, FIG. 2C is a cross-sectional view taken along the line CC ′, and FIG. 2D is a cross-sectional view taken along the line DD ′. FIG.
[0027]
The glass base material 10 has a structure in which the clad surrounds the side peripheral surface of the core, and has an elliptical cross section as shown in FIG. The length of the major axis is 25 mm, and the length of the minor axis is 15 mm. For such a glass base material, a substantially cylindrical optical fiber base material prepared by a general manufacturing method such as an OVD method, an MCVD method, or a rod-in-tube method is prepared, and the side surface of the cladding is mechanically ground. It can produce by doing.
[0028]
The motor 12 rotates the glass base material 10 about its axis. The rotation speed and rotation direction of the motor 12 are controlled by the control device 24.
[0029]
The heating furnace 14 heats and melts the tip of the glass base material 10. The outer diameter measuring device 20 disposed below the heating furnace 14 is viewed from one direction (hereinafter referred to as “measurement direction”) substantially perpendicular to the longitudinal direction of the optical fiber by a polarization method using a He—Ne laser. It measures the width of the optical fiber. The value measured is equal to the projection width of the optical fiber represented in a plane perpendicular to the measurement direction. The same applies to the outer diameter measuring device 22 installed below the outer diameter measuring device 20. The measurement data of the outer diameter measuring devices 20 and 22 is sent to the control device 24.
[0030]
The control device 24 obtains the twist information of the optical fiber based on the measurement data of the outer diameter measuring instruments 20 and 22, and controls the rotation of the motor 12 based on the twist information.
[0031]
The coating dies 30 and 34 cover the surface of the optical fiber with a liquid ultraviolet curable resin (UV resin), and the UV lamps 32 and 36 rapidly solidify the UV resin by irradiating ultraviolet rays. .
[0032]
The winding bobbin 50 winds up an optical fiber drawn from a glass base material at high speed. The guide rollers 40, 42 and 44 all guide the optical fiber moving toward the take-up bobbin 50, and the optical fiber is in contact with the roller surface.
[0033]
Next, the manufacturing method of the glass fiber using the apparatus of FIG. 1 is demonstrated. In this embodiment, the glass base material 10 is heated and melted at a temperature of about 2000 ° C. in a heating furnace 14 and drawn at a drawing speed of 100 m / min to produce an optical fiber. The cross section of the drawn optical fiber has an elliptical shape that is substantially similar to the cross section of the glass base material 10 as shown in FIG. The major axis has a length of about 125 μm and the minor axis has a length of about 75 μm.
[0034]
The drawn optical fiber moves along the longitudinal direction, and the width is measured by the outer diameter measuring devices 20 and 22 from a direction substantially perpendicular to the longitudinal direction.
[0035]
Next, the optical fiber is coated with a liquid UV resin with a coating die 30, and the UV resin is solidified by irradiation with UV light from a UV lamp 32. As a result, the primary coating is applied to the bare optical fiber, and the cross section of the optical fiber is as shown in FIG. Since the resin coated on the optical fiber by the coating die 30 is liquid, the coated optical fiber has a substantially circular cross section due to the surface tension of the resin.
[0036]
Subsequently, the optical fiber is secondarily coated with a UV resin by a coating die 34 and a UV lamp 36. As a result, the cross section of the optical fiber becomes a circle having a diameter of about 250 μm as shown in FIG.
[0037]
The secondary coated optical fiber is taken up by a take-up bobbin 50 through guide rollers 40, 42 and 44.
[0038]
Generally, in the drawing process of glass fiber, the glass fiber may be twisted. For example, in the manufacturing apparatus of FIG. 1, there may occur a case where the rotation axis of the guide roller 40 is not perpendicular to the moving direction of the optical fiber due to an arrangement error of the guide roller 40. In this case, the optical fiber is sent to the take-up bobbin 50 side while rolling on the roller surface of the guide roller 40. This applies a torque to the optical fiber that twists the optical fiber about its axis.
[0039]
Since the surface of the optical fiber coated with the UV resin is cured, the twist is hardly imparted. Accordingly, as shown in FIG. 1, twisting occurs when the optical fiber drawn from the glass base material 10 is in a relatively soft state from the outer diameter measuring devices 20 and 22 to the coating die 30. .
[0040]
The manufacturing apparatus according to the present embodiment measures the twist of the optical fiber using the outer diameter measuring devices 20 and 22, and appropriately rotates the glass base material 10 based on the obtained twist information, so that light without twisting can be obtained. An optical fiber with a desired twist is produced.
[0041]
A method for measuring torsion using the outer diameter measuring devices 20 and 22 will be described. Each of the outer diameter measuring devices 20 and 22 continuously measures the width of the optical fiber from a direction substantially perpendicular to the longitudinal direction, and data of measurement values obtained by each measuring device is sent to the control device 24, respectively. In the twist generation part, the optical fiber has an elliptical cross section as shown in FIG. 2B, and its width changes according to the direction to be measured. Therefore, when the optical fiber is twisted, the measured width value by the outer diameter measuring devices 20 and 22 changes with time according to the twist. The control device 24 obtains information on the twist of the optical fiber by comparing the time changes of the two measured values.
[0042]
FIG. 3 is a diagram illustrating the relationship between the direction of the optical fiber and the measurement direction of the outer diameter measuring devices 20 and 22. In FIG. 3, solid arrows 62 and 65 are measurement directions of the outer diameter measuring devices 20 and 22, respectively. Reference numeral 60 denotes a dotted line that passes through the center of an ellipse 68 that is a cross section of the optical fiber and is perpendicular to the measurement direction 62. A dotted line 61 is the major axis of the ellipse 68. The direction of the ellipse 68 can be defined by the angle θ formed by the dotted line 60 and the dotted line 61. A distance D1 between two alternate long and short dash lines 63 and 64 parallel to the arrow 62 and in contact with the outer periphery of the ellipse 68 is a measured value of the outer diameter measuring instrument 20. A distance D2 between two alternate long and short dash lines 66 and 67 parallel to the arrow 65 and in contact with the outer periphery of the ellipse 68 is a measured value of the outer diameter measuring device 22. The measuring directions 62 and 65 of the two outer diameter measuring devices form an angle of φ. φ is set to an angle other than 90 degrees × n (n is an integer).
[0043]
Here, parameters that define the twist of the optical fiber will be described. Considering an arbitrary point P0 on the axis of the optical fiber and a point P1 on the axis separated from this P0 by a predetermined distance along the longitudinal direction, the angle θ of the optical fiber cross section including P0 and perpendicular to the longitudinal direction And the angle θ of the cross section of the optical fiber including P1 and perpendicular to the longitudinal direction is the “twist angle” of the optical fiber between P0 and P1. When the twist angle is 360 °, the optical fiber rotates once between P0 and P1. The “twist amount” is defined as a twist angle per unit length of the optical fiber.
[0044]
In the following, as shown in FIG. 1, the distance between the outer diameter measuring devices 20 and 22 in the fiber longitudinal direction is represented by L, and the drawing speed of the optical fiber is represented by v. Specifically, the interval L between the outer diameter measuring devices 20 and 22 indicates the interval between the irradiation positions of the inspection laser beams of the outer diameter measuring devices 20 and 22.
[0045]
Since it is physically impossible to place two outer diameter measuring instruments at the same position, as shown in FIG. 1, the outer diameter measuring instruments 20 and 22 have different positions (different heights) along the longitudinal direction. Is arranged. For this reason, a difference arises in the time when the width of one place with an optical fiber is measured by two outer diameter measuring instruments. By correcting this time difference, it is possible to obtain the time change of the measured value when the outer diameter measuring device 22 is arranged at the same height as the outer diameter measuring device 20 and the width of the optical fiber is measured.
[0046]
If the measured width values detected by the outer diameter measuring devices 20 and 22 at a certain time t are D1 (t) and D2 (t), the time difference at which the same portion is measured by the two outer diameter measuring devices is L. Therefore, the measured value of the width when the outer diameter measuring device 22 is arranged at the same height as the outer diameter measuring device 20 is represented by D2 (t−L / v).
[0047]
FIG. 4 is a graph showing the change over time of the measured value (outer diameter output value) of the width of the optical fiber. The solid line indicates the measured value D1 (t) of the outer diameter measuring device 20, the alternate long and short dash line indicates the measured value D2 (t) of the outer diameter measuring device 22, and the dotted line indicates the measured value D2 (t− of the outer diameter measuring device 22 with the time difference corrected. L / v).
[0048]
As shown in FIG. 4, there is a phase difference between D1 (t) and D2 (t−L / v) in accordance with the angle φ formed by the measurement directions 62 and 65. If the twist amount of the optical fiber is α, the length of the optical fiber that passes through the inspection light irradiation position (hereinafter referred to as the measurement position) of the outer diameter measuring device 20 per unit time is equal to v. The twist angle between both ends of the portion that passes the measurement position of the outer diameter measuring instrument 20 per unit time is represented by α · v. This includes the measurement position of the outer diameter measuring device 20, and when considering a plane orthogonal to the axis of the optical fiber (this is equivalent to the paper surface of FIG. 3), the drawing of the optical fiber passing through this plane by drawing. This means that the cross section rotates by an angle of α · v per unit time. Therefore, the phase difference generated between D1 (t) and D2 (t−L / v) is represented by φ / (α · v).
[0049]
In this example, φ = 45 degrees, L = 0.3 m, v = 100 m / min, and L / v = 0.003 min = 0.18 sec. Therefore, D2 (t−L / v) = D2 (t−0.18 seconds). Φ and L can be obtained when the outer diameter measuring devices 20 and 22 are installed.
[0050]
As shown in the graph of D1 (t) in FIG. 4, the measured value of the width changes from a (= 125 μm) to b (= 75 μm) from time t = 0.0 to time t = 0.22. To do. This means that the angle θ representing the direction of the cross section of the optical fiber (the ellipse 68 in FIG. 3) has changed from 0 to 90 degrees as the optical fiber is twisted. However, D1 (t) alone cannot read whether the twist direction is clockwise or counterclockwise.
[0051]
Therefore, a graph of D2 (t−0.18 seconds) is referred to. The measured value gradually increases from time t = 0.0, and on the contrary, the measured value decreases after reaching the maximum value a. Assuming that the twist occurs counterclockwise, the measured width value gradually decreases from time t = 0.0, as is apparent from the fact that θ = 0 at time t = 0.0. The minimum value b should be reached. Therefore, it can be seen that the twist of the optical fiber occurs in the direction from the measuring direction 62 to 65, that is, clockwise as viewed from the heating furnace 14 side.
[0052]
In summary, when the measured value of the width by the outer diameter measuring instrument 20 is at the maximum value a, the measured value by the outer diameter measuring instrument 22 tends to increase, that is, the time derivative of the measured value is positive. In some cases, the twist direction is clockwise when viewed from the heating furnace 14 side. On the contrary, when the time derivative of the measured value by the outer diameter measuring device 22 is negative, the twist direction is counterclockwise when viewed from the heating furnace side.
[0053]
Further, from FIG. 4, since the phase difference (φ / (α · v)) = 0.11 seconds, when φ = 45 degrees and v = 100 m / min are used, the twist amount α of the optical fiber is about 245 degrees. / M.
[0054]
The control device 24 obtains the twist amount and the twist direction by the above method based on the measured value data of the width of the optical fiber sent from the outer diameter measuring devices 20 and 22. The controller 24 is pre-inputted with the amount and direction of twist that the manufactured optical fiber should have. The control device 24 compares the input data with the measured twist amount and twist direction, and if there is a difference, sends a control signal to the motor 12 to drive the motor and rotate the glass base material 10. Let By rotating the glass preform 10 at an appropriate rotation speed and direction, an optical fiber with a desired amount and direction of twisting is produced.
[0055]
When manufacturing an optical fiber without twist, the glass preform 10 is rotated in the direction opposite to the measured twist. The rotation speed is a speed at which a twist having the same pitch as the measured twist is applied to the optical fiber. As a result, the twist imparted to the optical fiber until now is canceled out, and an optical fiber free of twist can be obtained.
[0056]
FIG. 5 is a graph showing the results of measuring the twist angle of a 1 m long portion of the optical fiber drawn before and after the rotation of the glass base material 10. The dotted line indicates the twist angle before the glass base material 10 is rotated, and the solid line indicates the twist angle after the glass base material 10 is rotated. The twist angle is positive when viewed clockwise from the heating furnace 14 side.
[0057]
Prior to rotation, the twist angle increases substantially linearly along the length of the optical fiber, indicating that the optical fiber is twisted about its axis. On the other hand, after the rotation, the twist angle is maintained at almost 0 over a length of 1 m, indicating that almost no twist occurs. As described above, according to the above method, the twist is adjusted during the production of the optical fiber, and the optical fiber without the twist is easily produced.
[0058]
When an optical fiber to which a desired twist is imparted is manufactured, the twist caused by the rotation of the glass base material 10 can be further imparted to the twist caused by the placement error of the guide roller to adjust the twist.
[0059]
The present inventors have found that the twisted direction is clockwise when viewed from the heating furnace 14 side, the twist amount is 1980 degrees, in other words, the twisted light whose cross section is rotated 5.5 times per 1 m of the optical fiber. Attempted to manufacture fiber. After inputting the twist direction and the twist amount to the control device 24, the drawing of the optical fiber is started. The control device 24 calculates that the twist direction of the optical fiber generated without rotating the glass base material 10 is clockwise when viewed from the heating furnace 14 side, and the twist amount is 1080 degrees, and inputs this twist information. From the result of comparison with the twist information, the motor 12 was controlled so as to rotate the glass base material 10 clockwise by 300 rpm.
[0060]
FIG. 6 is a diagram illustrating a result of measuring the twist angle of the optical fiber after the glass base material 10 is rotated. The twist is uniformly applied over almost the entire length of the optical fiber, and as shown by the solid line, the cross section of the optical fiber is rotated about 5.5 times per meter, and an optical fiber having a desired twist is obtained. confirmed.
[0061]
Next, the inventors input new twist information to the control device 24, the twist direction is clockwise when viewed from the heating furnace 14, and the cross section of the optical fiber is rotated 0.5 times per meter. An attempt was made to produce an optical fiber with such a twist. In this case, the control device 24 controlled the motor 12 so as to rotate the glass base material 10 by 300 counterclockwise.
[0062]
The twist angle of the optical fiber manufactured in this way is also shown in FIG. It is confirmed that a twist is uniformly applied over almost the entire length of the optical fiber, and as shown by the dotted line, the cross section of the optical fiber is rotated about 0.5 times per meter, and an optical fiber having a desired twist is obtained. confirmed.
[0063]
Thus, according to the apparatus of the present embodiment, the control device 24 obtains the twist information of the drawn optical fiber, and controls the motor 12 based on this to determine the rotation direction and the rotation speed of the glass base material 10. Since the adjustment is performed, the amount and direction of twist applied to the optical fiber can be appropriately adjusted. Since the twist measurement of the optical fiber and the twist adjustment based on the measurement result are performed during the drawing, an optical fiber with a desired twist can be obtained easily and reliably.
[0064]
Although optical fibers are drawn so as to have the same cross section, glass fibers that are measured from a direction perpendicular to the longitudinal direction are not necessarily obtained due to the limitation of manufacturing technology. In general, there is a fluctuation of slightly less than 0.5% along the longitudinal direction of the width of the. Such variations due to manufacturing reasons also appear as time variations in the outputs of the outer diameter measuring devices 20 and 22. The change in time due to manufacturing reasons is not periodic, unlike the change in time of measurement values due to torsion, so identification is easy, but the maximum width of the optical fiber to be manufactured is 1.01 times the minimum value. If so, it is possible to more easily distinguish between changes in measured values due to torsion and changes due to manufacturing reasons.
[0065]
If the glass base material 10 whose maximum width is 1.01 times or more the minimum value is drawn, glass fiber whose maximum width is 1.01 times or more the minimum value can be drawn. If the glass base material 10 has a heating and melting temperature that is too high, the cross-sectional shape of the optical fiber obtained by the surface tension approaches a circle, and thus the heating temperature is preferably adjusted appropriately.
[0066]
In the present embodiment, the maximum value of the width of the glass base material 10 is 25 mm and the minimum value is 15 mm, and the maximum value is about 1.67 times the minimum value and 1.01 times or more. The maximum value of the width of the optical fiber manufactured by drawing the glass base material 10 is 125 μm, the minimum value is 75 μm, and the maximum value is about 1.67 times the minimum value and more than 1.01 times. Yes.
[0067]
Example 2
FIG. 7 is an overall configuration diagram showing the optical fiber manufacturing apparatus of the present embodiment. The manufacturing apparatus of the present embodiment is not provided with the motor 12 that rotates the glass base material 10 as in the first embodiment. A guide roller denoted by reference numeral 46 disposed immediately below the heating furnace 14 is a swing guide roller. This is a guide roller in which the roller rotation shaft periodically oscillates on a plane perpendicular to the paper surface of FIG.
[0068]
FIG. 8 is a view showing the swing of the swing guide roller 46 and is a plan view seen from the heating furnace 14 side. The rotation shaft of the swing guide roller 46 swings as shown by an arrow 48, and the swing guide roller 46 itself swings accordingly. This swinging is performed by an eccentric drive device (not shown) attached to the guide roller 46.
[0069]
The control device 24 obtains the twist information of the optical fiber based on the measurement data of the outer diameter measuring devices 20 and 22, and controls the swing of the swing guide roller 46 based on the twist information.
[0070]
Also in this example, the same optical fiber glass base material 10 as in Example 1 was used, and the glass base material 10 was heated and melted at a temperature of about 2000 ° C. in a heating furnace 14 and drawn at a drawing speed of 100 m / min. Go to make an optical fiber. The cross section of the drawn optical fiber is an ellipse having a major axis length of about 125 μm and a minor axis length of about 75 μm. Thereafter, the optical fiber is coated with UV resin, and the cross section of the optical fiber becomes a circle having a diameter of about 250 μm.
[0071]
In this embodiment, the optical fiber is drawn while swinging the swing guide roller 46 at a predetermined speed to manufacture a twisted optical fiber. Due to the swing of the swing guide roller 46, the optical fiber rotates on the roller surface while being sent to the guide roller 42, so that a torque around its axis acts on the optical fiber at the twist generating portion. This imparts twist to the optical fiber. The amount of twist depends on the swing speed of the swing guide roller 46.
[0072]
The control device 24 is preliminarily input with the amount and direction of twist that the manufactured optical fiber should have, and simultaneously with the start of drawing, the swing speed determined to be appropriate for applying the input twist. To swing the swing guide roller 46. When the drawing is started, the control device 24 obtains the twist amount and the twist direction by the same method as in the first embodiment. The control device 24 compares the measured twist amount and twist direction with the input data, and if there is a difference, sends a control signal to the eccentric drive device of the swing guide roller 46 to adjust the swing speed. To do. As a result, the optical fiber is twisted according to the input data, so that an optical fiber having a desired twist can be obtained with certainty.
[0073]
As mentioned above, although the Example of this invention was described in detail, this invention is not limited to the said Example, A various deformation | transformation is possible. For example, the glass fiber manufacturing apparatus of the present invention may include both the base material rotating motor of the first embodiment and the swing guide roller of the second embodiment.
[0074]
Further, the optical fiber may be drawn from the molten glass using a double crucible method instead of drawing from the glass base material. In this case, by adjusting the shape of the nozzle, it is possible to draw a glass fiber whose width measured from a direction substantially perpendicular to the longitudinal direction changes according to the measurement direction.
[0075]
In the embodiment, the two outer diameter measuring devices are used to obtain not only the twist amount but also the twist direction. However, it is often sufficient to obtain the twist amount using a single outer diameter measuring device. For example, when manufacturing an optical fiber that is twisted in a predetermined direction using a device in which the rotation direction of the glass base material is fixed, it is only necessary to control the rotational speed according to the amount of twist, and the optical fiber rotates according to the twist direction. There is no need to control the direction. The measurement value measured by the outer diameter measuring instrument shows a periodic change corresponding to the twist, and the period and the twist angle have a certain relationship according to the cross-sectional shape of the optical fiber. For example, in the case of the elliptical shape of the embodiment, the change of the measured value from the length “a” of the major axis to “a” means that the twist angle is 180 degrees. By utilizing this, it is possible to determine the amount of twist using a single outer diameter measuring instrument.
[0076]
Moreover, although the optical fiber was manufactured as one of the glass fibers in the embodiment, the twist can be adjusted in the same manner as in the embodiment even with a glass fiber other than the optical fiber.
[0077]
【The invention's effect】
As described above in detail, in the glass fiber manufacturing method of the present invention, the glass fiber is drawn while adjusting the twist generated in the glass fiber based on the twist information obtained during the manufacturing of the glass fiber. Desired glass fibers can be produced reliably and easily. Thereby, waste of glass fiber can also be prevented and a manufacturing yield can be improved.
[0078]
Further, according to the glass fiber manufacturing apparatus of the present invention, even when the twist of the glass fiber at the start of drawing is different from the desired one, the control means controls the twist imparting means based on the twist information, Since the twist is adjusted during drawing, a desired glass fiber can be produced reliably and easily.
[0079]
In the manufacturing apparatus of the present invention, when the measuring means measures the width of the glass fiber from the first and second measuring directions, not only the amount of twist but also the twist direction is obtained, and the control means is based on these information. Thus, the twist adjustment of the glass fiber is accurately performed, so that the desired glass fiber can be manufactured more reliably.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing a glass fiber manufacturing apparatus according to the present embodiment.
FIG. 2 is a view showing cross-sectional shapes of a glass base material 10 and an optical fiber.
FIG. 3 is a diagram showing the relationship between the direction of an optical fiber and the measuring direction of the outer diameter measuring devices 20 and 22;
FIG. 4 is a graph showing temporal changes in measured values (outer diameter output values) of the optical fiber width.
FIG. 5 is a graph showing a result of measuring a twist angle of a 1 m-long portion of an optical fiber drawn before and after rotation of a glass base material 10;
6 is a diagram showing a result of measuring the twist angle of the optical fiber after the glass base material 10 is rotated. FIG.
7 is an overall configuration diagram showing an optical fiber manufacturing apparatus according to Embodiment 2. FIG.
FIG. 8 is a view showing the swing of the swing guide roller 46;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Glass base material, 12 ... Motor, 14 ... Heating furnace, 20 ... Outer diameter measuring device, 22 ... Outer diameter measuring device, 24 ... Control apparatus, 30 and 34 ... Coating die, 32 and 36 ... UV lamp, 40, 42 and 44: guide rollers, 50: take-up bobbins.

Claims (6)

A method of manufacturing a glass fiber having a cross section of substantially the same shape along the longitudinal direction, the width of which is measured from a direction substantially perpendicular to the longitudinal direction changing according to the measurement direction,
A first step of drawing molten glass;
Twist the glass fiber by measuring the width of the glass fiber moving in the longitudinal direction during the drawing from the first and second measuring directions and comparing the changes in the measured values measured from the measuring directions. A second step for determining the amount and twist direction ;
A third step of adjusting the twist of the glass fiber based on the twist amount and twist direction ;
And the first measurement direction and the second measurement direction have an angle other than 90 degrees × n (n is an integer) . The first step is a step of heating and melting a columnar glass base material whose width measured from a direction substantially perpendicular to the axial direction changes according to the measurement direction,
The glass fiber manufacturing method according to claim 1, wherein the third step is a step of rotating the glass base material around its axis at a rotation speed and a rotation direction according to the twist information.   The third step is a step of guiding the glass fiber with a swinging guide roller having a roller surface in contact with the glass fiber and swinging the guide roller at a swinging speed according to the twist information. The method for producing a glass fiber according to claim 1. An apparatus for producing glass fiber by drawing a molten glass having a cross section having substantially the same shape along the longitudinal direction, the width measured from a direction substantially perpendicular to the longitudinal direction changing according to the measurement direction,
A heating means for heating and melting the columnar glass base material;
Measuring means for measuring the width of the glass fiber drawn from the glass base material and moving in the longitudinal direction;
Twist imparting means for twisting the glass fiber;
Control means for obtaining twist information of the glass fiber based on a change in the measurement value output from the measurement means, and controlling the twist imparting means based on the twist information;
A winding means for winding the glass fiber measured by the measuring means;
With
The measuring means measures the width of the glass fiber from the first and second measuring directions,
The first measurement direction and the second measurement direction form an angle other than 90 degrees × n (n is an integer),
The said control means is a glass fiber manufacturing apparatus which calculates | requires the twist amount and twist direction of the said glass fiber by comparing the change of the measured value measured from each said measurement direction . The twist imparting means is a base material rotating means for rotating the glass base material around its axis;
The said control means controls the said base material rotation means, The said glass base material is rotated by the rotational speed and rotation direction according to the said twist information, The manufacturing apparatus of the glass fiber of Claim 4 characterized by the above-mentioned. . The twist imparting means is a guide roller that has a roller surface that contacts the glass fiber and swings,
5. The glass fiber manufacturing apparatus according to claim 4, wherein the control means swings the guide roller at a swing speed corresponding to the twist information.

Images