JP2000185932A - Apparatus for drawing optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for drawing optical fiber capable of making improvement of the optical fiber strength compatible with improvement of the productivity. SOLUTION: This apparatus for drawing optical fibers is used for drawing optical fiber by heating an optical fiber preform 1. The drawing apparatus is equipped with a disk-like take-off capstan 7 for taking off coated optical fiber. Passage of the optical fiber is set to that contact angle which is a center angle of circular arc of a take-off capstan corresponding to contact part of the take-off capstan with optical fiber becomes 100 deg. to 200 deg.. The frictional force between the optical fiber and the take-off capstan is increased by increasing contact area between both of them and drawing of optical fiber at high drawing speed can be carried out without using a pressing belt 10. Further, the coated optical fiber is prevented from causing damage by optical fiber fragments attached to the pressing belt and lowering of optical fiber strength can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber drawing apparatus used to obtain an optical fiber by heating and drawing an optical fiber preform.

[0002]

2. Description of the Related Art Conventionally, there has been known an optical fiber drawing apparatus used to obtain an optical fiber by heating and drawing an optical fiber preform obtained by, for example, a VAD method (see, for example, Japanese Patent Application Laid-Open No. 202053).
In this apparatus, a drawing furnace for heating an optical fiber preform, an outer diameter measuring device for measuring the outer diameter of the optical fiber drawn from the drawing furnace, and a resin coating on the optical fiber are used. A resin-coated die to be applied, a resin curing device for curing the resin coating covered by the resin-coated die, a take-up capstan for drawing the resin-coated optical fiber, and a winding machine for winding the coated optical fiber And

[0003] The take-off capstan is formed of metal or the like, and a frictional force between the take-up capstan, the optical fiber core wire and the coated optical fiber (hereinafter, abbreviated as optical fiber or the like). Is small. For this reason, a pressing belt made of rubber or the like for holding the optical fiber or the like against the capstan is provided, and the holding belt is used to press the optical fiber or the like against the capstan. The optical fiber and the like are taken up by preventing slippage between them.

[0004] In the optical fiber drawing apparatus as described above, the drawing of the optical fiber is performed as follows.

[0005] That is, an optical fiber preform is heated and melted by a drawing furnace and drawn to form an optical fiber core. Then, first, without attaching the resin-coated dies to predetermined positions,
In addition, the optical fiber core is passed through the resin curing device, and the optical fiber core is driven by driving the take-up capstan while being sandwiched between the take-up capstan and the pressing belt. While the optical fiber core is being taken out by the capstan in this way, the rotation speed of the capstan is adjusted in accordance with the measurement value of the outer diameter measuring device, and the outer diameter of the optical fiber core is adjusted to a desired value. To do it.

When the outer diameter of the optical fiber becomes a desired value, the resin-coated die is attached to a predetermined position, and the optical fiber is passed through the resin-coated die.
In addition, an uncured ultraviolet curable resin is supplied to the resin-coated die. Then, ultraviolet irradiation is started from a resin curing device serving as an ultraviolet irradiation source, and a coating layer is applied to the outside of the optical fiber core. In this way, a coated optical fiber is obtained, and the coated optical fiber is wound by a winder.

[0007]

However, in the above-described conventional optical fiber drawing apparatus, when the drawing speed is adjusted before resin coating, fragments of the optical fiber core wire are formed on the pressing belt. There is a disadvantage that it adheres. If the fiber pieces adhere to the holding belt in this way, when the resin-coated optical fiber is pulled, the surface of the coated optical fiber will be damaged, and as a result, the optical fiber strength will be reduced. There is a problem that it is significantly reduced. For this reason, there is an inconvenience that the probability of breaking the optical fiber (breaking probability) increases.

To solve this problem, it is conceivable to draw an optical fiber without using the pressing belt.

However, in this case, since the frictional force between the coated optical fiber and the take-up capstan is small, slippage occurs between the two, and it is difficult to increase the drawing speed of the optical fiber. There is a problem that it becomes. As a result, there is a disadvantage that productivity is reduced. In addition, by the occurrence of the above-mentioned slip,
The coated optical fiber cannot be taken out constantly, and as a result, inconveniences such as non-uniformity of the optical fiber may occur.

As described above, in the conventional optical fiber drawing apparatus, it is possible to prevent the strength of the optical fiber from deteriorating due to the fiber piece attached to the holding belt, and to improve the productivity of the optical fiber by increasing the drawing speed. Is a conflicting demand.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a drawing apparatus for an optical fiber, which can prevent both a reduction in the strength of the optical fiber and an improvement in productivity. It is in.

[0012]

In order to achieve the above object, the present inventor has paid attention to the point that if the frictional force between the take-off capstan and the optical fiber is increased, it is not necessary to use a holding belt. The present invention has been completed. That is, the contact angle, which is the central angle of the arc of the take-up capstan corresponding to the area where the take-up capstan and the optical fiber are in contact, is conventionally set to about 90 ° (see FIG. 3). Here, if the contact angle is increased, even if the friction coefficient between the optical fiber and the take-off capstan is small, the frictional force between the optical fiber and the take-up capstan is increased by an amount corresponding to an increase in the contact area between the two. Will be able to In view of this, the present invention has been completed.

More specifically, the present invention is directed to an optical fiber drawing apparatus for drawing an optical fiber by heating an optical fiber preform. In this apparatus, a disk-like drawing apparatus for drawing the drawn optical fiber is provided. Capstan shall be provided. The take-up capstan is configured to draw the optical fiber by aligning the optical fiber with the peripheral surface of the take-up capstan, and the peripheral surface of the take-up capstan and the optical fiber are in contact with each other. The specific matter is that the contact angle, which is the center angle of the arc of the take-up capstan corresponding to the range, is set to be equal to or larger than the angle at which no slip occurs between the peripheral surface of the take-up capstan and the optical fiber. Is what you do.

In this case, the contact area between the optical fiber and the peripheral surface of the take-off capstan is increased as compared with the prior art, and as a result, the frictional force between the two can be increased. For this reason, it is possible to prevent the optical fiber from slipping without using a holding belt when the drawing speed is increased. As described above, by not using the pressing belt, the optical fiber is prevented from being damaged by a piece of fiber or the like attached to the pressing belt, and a decrease in breaking strength is prevented. Moreover, since the drawing speed can be increased without using the holding belt, the productivity is improved.

[0015] If the contact angle is too large, for example, the optical fiber may be twisted.
It is desirable that the angle be from 200 to 200 °. Further, when the contact angle is set to 150 ° to 200 °, for example, 200 m / min which is a drawing speed for drawing a normal optical fiber is used.
Even at the above drawing speed, it is possible to draw the optical fiber without causing slippage between the take-off capstan and the optical fiber.

[0016]

As described above, according to the optical fiber drawing apparatus of the present invention, it is possible to prevent both a decrease in the breaking strength of the optical fiber and an increase in the drawing speed. it can.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a drawing apparatus according to an embodiment of the present invention, and 2 has a heater for heating and preserving an optical fiber preform 1.
A drawing furnace for drawing, 4 an outer diameter sensor for detecting the outer diameter of the optical fiber core 1a by a laser beam, 5 a resin coating die for coating the optical fiber core 1a with a resin, and 6 an ultraviolet curing resin coating. Curing device to cure with 7
Is a take-up capstan driven to take up the coated optical fiber 1b, 8 is a screening means for removing slack during winding, 9 is a winding machine for winding the coated optical fiber 1b, and 10 is the winding machine for winding the coated optical fiber 1b. Optical fiber core 1a
And a pressing belt for pressing the pressing belt against the capstan 7.

In this drawing apparatus, the front end of the optical fiber preform 1 is heated in a drawing furnace 2 to draw an optical fiber core 1a. The optical fiber core 1a is coated with a resin-coated die 5 and a resin cured resin. The coating layer is formed by the vessel 6 to obtain the coated optical fiber 1b. Further, at the time of drawing, the drawing capstan 7 controls the drawing speed in accordance with the detection result of the outer diameter sensor 4.

Then, as shown in FIG. 2, depending on the arrangement position of the pulley of the screening means 8, the take-off corresponding to the area where the peripheral surface of the take-up capstan 7 is in contact with the coated optical fiber 1b. Capstan 7
The path of the coated optical fiber 1b is set so that the central angle (contact angle) θ of the circular arc becomes 150 °.

As shown in FIG. 1, the pressing belt 10 is configured to be retractable with respect to the take-up capstan 7 by, for example, a hydraulic cylinder (not shown) (see a solid line and a dashed line in FIG. 1). ).

Next, an optical fiber drawing process using the optical fiber drawing apparatus will be described.

The optical fiber preform 1 is heated and melted by the drawing furnace 2 and drawn to obtain an optical fiber core 1a. First, the resin-coated die 5 is not attached to a predetermined position, and the optical fiber is passed through the resin curing device 6.
0 and the capstan 7
Is driven to take out the optical fiber core 1a. As described above, while the optical fiber core 1a is being taken by the take-up capstan 7, the rotation speed of the take-up capstan 7 is adjusted according to the measurement value of the outside diameter sensor 4, and the outer diameter of the optical fiber core 1a is adjusted. Is set to a desired value.

When the outer diameter of the optical fiber core 1a becomes a desired value, the resin-coated die 4 is attached to a predetermined position, an optical fiber is passed through the resin-coated die 4, and An uncured ultraviolet curable resin is supplied to the coating die 4. Then, ultraviolet irradiation is started from the resin curing device 6, and a coating layer is applied to the outside of the optical fiber core wire 1a. Thus, the coated optical fiber 1b is obtained, and the coated optical fiber 1b is obtained.
Is wound up by the winder 9 via the screening device 8. At this time, the pressing belt 10 is kept in a retracted state from the take-up capstan 7 (see the solid line in FIG. 1).

Next, the operation and effect of the above embodiment will be described.

The contact angle of the take-up capstan 7 is set to 15
By setting it to 0 °, the contact angle becomes 9
As compared with the case where the angle is 0 °, the contact area between the coated optical fiber 1b and the take-up capstan 7 can be increased. For this reason, the frictional force between the two increases, and as a result, drawing can be performed at a high drawing speed without using the holding belt 10. As a result, even if the optical fiber piece adheres to the pressing belt 10, the surface of the coated optical fiber 1b is prevented from being damaged, and the decrease in the breaking strength of the optical fiber is prevented. Will be able to

Further, by realizing a high drawing speed, it is possible to improve the productivity, and further, by preventing the coated optical fiber 1b from slipping, it is possible to keep the coated optical fiber 1b constant. Since the coated optical fiber 1b can be taken out, uniformity can be achieved.

The contact angle θ may be set to, for example, 100 ° to 200 °.
This is a geometrically acceptable range from the relative positional relationship between the take-up capstan 7 and the screening means 8. If the contact angle θ is too large, the coated optical fiber 1b may be twisted. Therefore, the contact angle is desirably 200 ° or less. Further, as the contact angle θ, for example, 150 °
If the angle is set to about 200 °, the optical fiber is normally drawn without slipping between the take-up capstan 7 and the coated optical fiber 1b even at a drawing speed of 200 m / min for drawing the optical fiber. The fiber can be drawn.

[0029]

Next, an embodiment in which the contact angle θ is 150 ° will be described.

When the contact angle of the take-up capstan 7 is 90 ° as in the prior art (see FIG. 3), when the holding belt 10 is not used, the drawing speed is 200 m / mi.
At n, slippage occurred between the coated optical fiber 1b and the take-up capstan 7.

On the other hand, when the contact angle θ was set to 150 ° (see FIG. 2), no slippage occurred even when the drawing speed was 1000 m / min when the holding belt 10 was not used. For this reason, it was found that if the contact angle θ was increased, the drawing speed could be improved.

In the case where the optical fiber is drawn using the holding belt 10, the distance is from 80 km to 90 km.
When the optical fiber was wound, a break occurred once.

On the other hand, when the pressing belt 10 was not used, once the optical fiber of 150 km to 200 km was wound up, the optical fiber was broken only once, and the optical fiber became hard to break. For this reason, unless the holding baltic 10 is used, a decrease in the strength of the optical fiber is prevented,
As a result, it was found that the fracture probability could be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a partial cross section showing an optical fiber drawing apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a contact angle between a take-off capstan and an optical fiber.

FIG. 3 is an explanatory view showing a contact angle between a conventional take-up capstan and an optical fiber.

[Explanation of symbols]

 Reference Signs List 1 optical fiber preform 7 take-up capstan 1a optical fiber core wire (optical fiber) 1b coated optical fiber (optical fiber) θ contact angle

Claims (2)

[Claims] 1. An optical fiber drawing apparatus for heating an optical fiber preform to draw an optical fiber, comprising: a disk-shaped drawing capstan for drawing the drawn optical fiber; The optical fiber is wound around the peripheral surface of the take-up capstan so as to take the optical fiber, and the take-up capstan corresponding to the area where the peripheral surface of the take-up capstan is in contact with the optical fiber. An optical fiber drawing device, wherein a contact angle, which is a central angle of an arc, is set to be equal to or larger than an angle at which a slip does not occur between a peripheral surface of the take-up capstan and the optical fiber. 2. The optical fiber drawing apparatus according to claim 1, wherein the contact angle is set to be 100 ° to 200 °.