JPS6177632A - Process for preventing vibration of optical fiber during wire drawing and wire drawing device therefor - Google Patents

Abstract

PURPOSE:To reduce vibration of optical fiber between a parent material and a guiding means to the least extent in the stage for guiding an optical fiber parent material during heating, wire-drawing, and cladding, by providing a means for adjusting the distance between the parent material and the guiding means. CONSTITUTION:An optical fiber parent material 10 is held vertically and transferred downward at a fixed speed, drawn by heating in a wire drawing furnace 14, and the optical fiber 16 suspended downward is transferred to a primary cladding device 20 after passing the fiber through a fiber size measuring device 18, where the drawn optical fiber is clad with a plastic material. The fiber is then passed between a capstan 24 and an idle roller 26 through a drying furnace 22. In this stage, a fixed tension is given to a tension roller 30, and the fiber is wound on a winding drum 32. A pinion 46 provided to a capstan guide 34 is then revolved, and a block 40 is moved upward or downward along a groove 38 of the capstan guide 34 to adjust the distance between the lowermost end of the parent material 10 and the capstan 24 so as to reduce the degree of vibration of the optical fiber 16 to the least extent. By this method, the dia. and the clad of an optical fiber 16 are regulated to fixed values.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for preventing vibration of an optical fiber during drawing of an optical fiber, and an optical fiber drawing apparatus for the same.

BACKGROUND ART An optical fiber preform made to have a diameter of about 20 mm to 25 mm is drawn by an optical fiber drawing device into an optical fiber having an outer diameter of 100 to 150 μm and a length of several kilometers to several tens of kilometers.

FIG. 5 is a diagram showing a schematic configuration of such a wire drawing device. In the illustrated drawing apparatus, an optical fiber preform 10
is supported almost vertically by a base material feeding device 12 and fed into a drawing furnace 14 at a constant speed. The drawing furnace 14 is a heating furnace that heats the optical fiber preform 10 to a high temperature of 2000° C. or higher, and is, for example, a resistance furnace, an induction heating furnace, or the like.

The outer diameter of the optical fiber 16 that has been drawn in the drawing furnace 14 and hanging down is measured by a wire diameter measuring device 18 using, for example, a He-Ne laser.
Next, the coating device 20 coats the plastic. This plastic coating is done to protect the optical fiber, since a drawn glass optical fiber is brittle and its strength is significantly reduced by external damage, and is usually 10 to 100 μm thick. It is made to a certain thickness. For this purpose, the primary coating device 20 includes, for example,
The surface of the optical fiber 16 is coated with a coating material such as silicone resin, polyurethane, or epoxy. The primary coating device 20
A drying oven is provided below to dry the plastic coated on the optical fiber.

The optical fiber 16 thus coated with plastic is fed between a capstan 24 and an idler roller 26, and tension rollers provided at both ends of a tension bar 28 that apply a constant tension to the optical fiber 12. 30 and is wound onto a winding drum 32. In addition,
The tension bar 28 applies tension to the optical fiber wound on the winding drum 32 so that the optical fiber is wound on the winding drum 32 without loosening.

Furthermore, the output of the wire diameter measuring device 18 is input to a wire diameter control device 18A, and the wire diameter control device 18A is connected to the optical fiber 16.
The outer diameter measurement value of the optical fiber 16 is compared with the reference value, and the number of revolutions of the capstan 240
Control the tensile force against. That is, when the measured value is larger than the reference value, the rotational speed of the capstan 24 is increased, and on the other hand, when the measured value is smaller than the reference value, the rotational speed of the capstan 24 is decreased.

In the conventional optical fiber drawing apparatus as described above, the optical fiber preform 10 held by the preform feeder 12 to the capstan 24 are vertically aligned in a straight line.

Therefore, during drawing, the vibrations of the motor of the drawing device itself or the combined vibrations of the factory are transmitted to the optical fiber 18, and the optical fiber between the optical fiber base material 10 and the capstan 24 is affected by the dimensions of the optical fiber or its characteristics. It often vibrated like a string in response to

FIG. 6 is a diagram showing an example of the vibration mode of such an optical fiber. In FIG. 6, the position This is the amount of displacement of the fiber. However, in conventional line drawing, no measures have been taken to address this problem. On the other hand, in the past, various types of optical fibers have been drawn using the same drawing device, and although there may be cases where the vibrations are small due to coincidence, in the case of drawing most optical fibers, the above-mentioned vibrations are It remained abandoned. Therefore, the optical fiber resonates, the amplitude of which is often significant, and the capstan
4 may cause an unnecessary force to act on the optical fiber in addition to the amount of tensile force exerted on the optical fiber, or the position within the primary coating device may change, resulting in a change in the optical fiber diameter or the secondary coating. Eccentricity, that is, thickness unevenness occurs, which causes optical fiber stiffness.

Problems to be Solved by the Invention Conventionally, as mentioned above, the vibrations generated during wire drawing have been ignored, causing optical fiber spring failure.

SUMMARY OF THE INVENTION Therefore, the present invention aims to provide a method for preventing vibration of an optical fiber during drawing of an optical fiber, and a drawing apparatus for the same.

Means for Solving the Problems As a result of various studies on the above-mentioned problems, the inventor of the present invention has found that
The vibration mode of this optical fiber exists in a form specific to the type of optical fiber manufactured, and therefore, the vibration mode will differ if the diameter or composition of the optical fiber differs. Additionally, the frequency and magnitude of vibrations transmitted through optical fibers vary. Therefore, even if the vibration of the optical fiber section between the optical fiber base material and the capstan is simulated as the vibration of a string, the frequency and magnitude of the vibration transmitted to the optical fiber will vary, and the Vibration of the fiber cannot be prevented.

On the other hand, the vibration of the optical fiber section between the optical fiber preform and the capstan is regulated by various factors such as the length of the optical fiber section, the weight, and the tension acting on the section. Therefore, by changing one of these factors, vibration of the optical fiber can be suppressed. However, for example, changing the weight of an optical fiber means changing the cross-sectional area of the optical fiber, since the composition of the optical fiber cannot be changed, and the optical fiber will no longer meet the intended specifications. Furthermore, changing the tension acting on the optical fiber also changes the diameter of the optical fiber, making it no longer an optical fiber of the intended standard.

The inventor of the present invention has found that among the factors that regulate vibration, adjusting the distance between the optical fiber preform and the capstan is a vibration mode of the optical fiber portion between the optical fiber preform and the capstan. I discovered that it is possible to make practical changes.

The present invention was made based on this idea.

That is, according to the present invention, an optical fiber preform is heated by a drawing furnace, and the optical fiber is suspended from the lower end thereof, and a primary coating device disposed below the drawing furnace allows the light that hangs from the drawing furnace to be heated. caused by vibrations transmitted to the optical fiber when the optical fiber is coated and the coated optical fiber hanging down is directed in another direction by a guiding means disposed below the primary coating device. The distance between the optical fiber preform and the guiding means is adjusted so as to minimize the vibration of the optical fiber portion between the optical fiber preform and the guiding means. A vibration isolation method is provided.

Furthermore, according to the present invention, there is provided a drawing furnace that heats an optical fiber preform and suspends the optical fiber from the lower end thereof, and a primary coating device disposed below the drawing furnace that coats the optical fiber hanging from the drawing furnace. , and a guide means disposed further below the optical fiber for directing the hanging coated optical fiber in another direction, wherein the guide means is vertically adjustable in position. An optical fiber drawing apparatus with features is provided.

Effect: According to the optical fiber vibration isolation method according to the present invention as described above, even if vibrations propagate to the optical fiber, the vibration from the optical fiber base material to the guiding means, which is one of the factors regulating the vibration of the optical fiber, can be reduced. Since the distance is changed so that the amplitude of the vibration of the optical fiber is minimized, it is possible to prevent the occurrence of large lateral vibration of the optical fiber due to the occurrence of resonance.

Even if the distance from the optical fiber base material to the guiding means is changed in this way, the outer diameter of the optical fiber does not change, unlike when the tension applied to the optical fiber is changed, and the drawing conditions do not change. An optical fiber with a stable diameter can be obtained.

Furthermore, with the optical fiber drawing apparatus according to the present invention described above, simply by adjusting the position of the guide means up and down,
You can easily change the distance from the base material held in the base material feeding section to the guiding means, which is one of the factors that regulates the vibration of optical fibers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an optical fiber vibration isolation method for optical fiber drawing and an optical fiber drawing apparatus therefor according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a diagram showing one embodiment of an optical fiber drawing apparatus according to the present invention that can implement the optical fiber vibration isolation method in optical fiber drawing according to the present invention. In addition, the fifth
The same parts as in the conventional optical fiber drawing apparatus shown in the figure are given the same reference numerals.

The illustrated optical fiber drawing apparatus has a preform feeding device 12 that supports an optical fiber preform 10 almost vertically and sends it downward at a constant speed. Below the preform feeding device 12,
A drawing furnace I4 is arranged to heat the lower end of the optical fiber preform 10 to locally soften it.

A wire diameter measuring device 18 is located below the drawing furnace 14.
is placed, and the outer diameter of the optical fiber 16 hanging down from the drawing furnace 14 is measured. A primary coating device 20 and a drying oven 22 are arranged below the wire diameter measuring device 18.

Furthermore, a capstan 24 and an idle roller 26 are arranged below the drying oven 22, and a tension roller 3 is placed on the side of the capstan 24 and idle roller 26.
Tension bar 28 with 0 at both ends, winding drum 3
2 is placed.

Further, the output of the wire diameter measuring device 18 is manually inputted to the wire diameter control device 18A, and the wire diameter control device 34 compares the measured value of the outer diameter of the optical fiber 16 with a reference value and determines the rotation speed of the capstan 24. Control.

Since the configuration up to the above-mentioned portions is the same as the conventional optical fiber drawing apparatus shown in FIG. 5, further explanation of the configuration and operation of the above-mentioned portions will be omitted.

In addition to the above configuration, in this embodiment, the capstan 24 and the idle roller 26 are made movable in the optical fiber drawing direction by a capstan guide 34.

FIG. 2 is a diagram showing details of the capstan guide 34.

The capstan guide 34 is vertically fixed to a floor surface 36 and has a vertical groove 38 in its center. A block 40 having a width substantially the same as the width of the groove 38 is disposed in the groove 38 so as to be movable along the groove 38. The shaft 24A of the capstan 24 and the shaft 26A of the idle roller 26 are rotatably held in the block 40. The shaft 24A of the capstan 24 is attached to the opposite side of the block 40 from the capstan 24. It is integrated with the shaft of the motor 42.

Further, racks 44 are formed on both sides of the block 40, and a pinion 46 is rotatably mounted inside the cab stan guide 34 so as to mesh with the racks 44. The pinion 46 is rotated when necessary by suitable drive means.

Thus, by rotationally driving the pinion 46, the block 40 can be moved up and down along the groove 38 of the capstan guide 34. That is, the capstan 24 and the idle roller 26 can be vertically displaced by the capstan guide 34. Note that the length of the capstan guide 13 is determined depending on the required movable distance of the capstan 24.

Therefore, in the optical fiber drawing apparatus implementing the present invention described above, the capstan 2 is moved along the capstan guide 34.
4 can be moved up and down, and by raising and lowering the capstan 24 in this way, the distance between the lower end of the optical fiber preform 12 and the capstan 24 can be changed.

FIG. 3 is a diagram illustrating an optical fiber vibration isolation method according to the present invention using the above-described optical fiber drawing apparatus.

When the optical fiber preform 10 is set in the preform feeder 12 and the optical fiber is drawn, the optical fiber 16 may be drawn as shown in FIG. 3(a) depending on various drawing conditions. Vibration occurs between the lower end of the base material 10 and the contact point of the capstan 24. Although FIGS. 3(a) and 3(a) illustrate the primary coating device 20, this is to show the position of the primary coating device 20, and the vibration of the optical fiber itself is caused by the primary coating device 20. It shows the vibration when there is no 20.

In this way, when the optical fiber 16 vibrates between the lower end of the optical fiber preform 10 and the capstan 24, an unnecessary force other than the tensile force exerted on the optical fiber by the capstan 24 acts on the optical fiber. Therefore, the optical fiber diameter varies. Furthermore, as shown in FIG. 3(a), 1
Next, when the optical fiber 16 is displaced considerably in a direction perpendicular to its axis at the position of the coating device 20, the optical fiber 16
is pressed against the side wall of the primary coating device 20, resulting in eccentricity of the secondary coating or uneven thickness of the primary coating.

The vibration mode of the optical fiber 16 as described above depends on the optical fiber material such as the length, cross-sectional area, Young's modulus, Poisson's ratio, mass density, etc. of the optical fiber 16 between the lower end of the optical fiber base material 10 and the capstan 24. It can be obtained by a method such as the finite element method from data and pre-measured vibration data of the base material chuck part of the base material feeder, such as constant slight vibrations and pulsations, or it can be obtained by actual measurement.

Then, the capstan 24 is moved up and down along the capsun guide 34 to change the distance between the lower end of the optical fiber preform 10 and the capstan 24, and each time the vibration mode is actually measured as described above. Alternatively, computer simulation is performed and the distance between the lower end of the optical fiber preform 10 and the capstan 24 is adjusted to the span of the vibration mode with the minimum maximum amplitude.

An example of the vibration mode in such a case is shown in FIG.

In the example shown in Fig. 3, etc., as can be seen by comparing with Fig. 3(a), the capstan 24 is lowered and the base material 10 is
By increasing the distance between the lower end of the capstan 24 and the capstan 24, vibrations are reduced.

Considering the actual drawing, the vibration of the optical fiber is
As long as it can be reduced to an extent that does not affect the diameter of the optical fiber, it is not necessarily necessary to set the vibration mode to the minimum maximum amplitude. Rather, if the vibration of the optical fiber can be reduced to such an extent that it does not affect the diameter of the optical fiber, it is preferable to make the primary coating uniform even if the effect on the diameter of the optical fiber is sacrificed to some extent. .

Therefore, as shown in FIG. 4, the distance between the lower end of the optical fiber preform 10 and the capstan 24 is adjusted to create a vibration mode in which the lateral displacement at the position of the primary coating device 20 is zero. However, if this is not possible, the vibration mode is such that the minimum amplitude of the optical fiber is located in the primary coating device 20. As described above, if the displacement of the optical fiber 16 in the primary coating device 20 is substantially zero, a primary coating with a uniform thickness without eccentricity can be realized.

In the embodiment of the optical fiber drawing apparatus described above, the capsun guide 34 incorporating a rack and pinion is used as a means for moving the capstan 24 up and down, but the cooperative relationship between the capstan 24 and the idle roller 26 is Any device can be used as long as it can move the capstan 24 and idler roller 26 in the vertical direction while maintaining the position.

In the embodiment of the optical fiber drawing apparatus described above, there is also a means for applying a tensile force to the optical fiber hanging down from the drawing furnace 14 through the primary coating apparatus 20 and directing the optical fiber in a direction different from the vertical direction. As such, a cooperating capstan and idler roller are used, but any means capable of achieving such an effect may be used.

Effects of the Invention As is clear from the above explanation, according to the optical fiber vibration isolation method according to the present invention, the distance between the lower end of the optical fiber preform and the guiding means is adjusted, and the optical fiber drawing device itself or It is possible to minimize the influence of vibration transmitted from peripheral equipment in the factory, reduce the vibration of the optical fiber, and minimize the unnecessary force acting on the optical fiber.As a result, the diameter of the optical fiber can be kept constant. It can be done.

Further, by utilizing the optical fiber vibration isolation method according to the present invention, the amplitude of the optical fiber at the position of the primary coating device can be made substantially zero, making it possible to uniformly coat the optical fiber with the primary coating. do.

Moreover, according to the optical fiber drawing apparatus according to the present invention described above, the distance between the lower end of the optical fiber preform and the guide means can be adjusted very easily.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the optical fiber drawing apparatus of the present invention, FIG. 2 is a diagram showing details of the cab scan guide of the optical fiber drawing apparatus shown in FIG. 1, and FIG. a) and (b)
4 is a diagram illustrating the principle of the optical fiber vibration isolation method in optical fiber drawing of the present invention. FIG. FIG. 5 is a schematic configuration diagram showing one configuration of a conventional optical fiber drawing device. FIG. 6 is a diagram illustrating vibration modes of an optical fiber in a conventional optical fiber drawing device. It is. [Main reference number]

Claims (5)

[Claims] (1) heating an optical fiber preform in a drawing furnace to make the optical fiber hang from its lower end; coating the optical fiber hanging from the drawing furnace with a primary coating device disposed below the drawing furnace; The guide means disposed below the primary coating device directs the hanging coated optical fiber in another direction, and when drawing the optical fiber, the optical fiber motherboard is caused by vibrations transmitted to the optical fiber. 1. A method for vibration isolating an optical fiber, comprising adjusting a distance between the optical fiber preform and the guide means so as to minimize vibration of the optical fiber portion between the preform and the guide means. (2) Furthermore, the smallest part of the vibration amplitude of the optical fiber portion between the optical fiber preform and the guide means caused by the vibration transmitted to the optical fiber is applied to the portion of the primary coating device. The optical fiber vibration isolation method according to claim 1, characterized in that the distance between the optical fiber preform and the guide means is adjusted so that the optical fiber preform and the guide means are located in the same position. (3) A drawing furnace that heats an optical fiber preform and suspends the optical fiber from its lower end; a primary coating device disposed below the drawing furnace that coats the optical fiber hanging from the drawing furnace; An optical fiber drawing apparatus comprising at least a guide means arranged to direct a coated optical fiber hanging down in another direction, wherein the guide means is vertically adjustable in position. line drawing device. (4) The optical fiber drawing device according to claim (3), wherein the guide means is a capstan that pulls the coated optical fiber downwardly hanging from the primary coating device. (5) The shaft of the capstan is slidably supported along the groove of a capstan guide, which has a groove provided parallel to the direction in which the optical fiber hangs, and is provided parallel to the direction in which the optical fiber hangs. Claims characterized in that the capstan is rotatably held by a block having a rack, and the capstan is moved up and down by driving a pinion provided in the capstan guide so as to mesh with the rack. The optical fiber drawing device according to item (4).