JP3344634B2 - Optical fiber drawing apparatus and drawing method using the same - Google Patents

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 having a dancer device capable of stably winding an optical fiber drawn at a high speed and a drawing method using the same. It is.

[0002]

2. Description of the Related Art The drawing speed of a silica-based optical fiber is technically attained, for example, at 1200 m / min or more using an apparatus as shown in FIG. 3 (S. Sakaguchi & T). .Kimura, J. Lightwave Technology,
LT-3, 1985, 669-673). Further, it is practically produced at a speed of 300 m / min or more. This speed is comparable to the production speed of the copper core wire (approximately 500 to 1500 m / min), and corresponds to the widespread use of optical fibers. In FIG. 3, reference numeral 1 denotes a pulley, 2 denotes an arm,
Is a balancer, 4 is an optical fiber, 5 is a preform feed, 6 is an optical fiber preform, 7 is a carbon resistance furnace, 8 is a wire diameter measuring instrument, 9 is
Is a pressure source, 10 is a pressure regulating valve, 11 is an exhaust, 12 is a coating resin, 13 is a pressing die, 14 is an ultraviolet curing furnace, 15 is a tension measuring device, 16 is a capstan, and 17 is a winding means. I do.

There are some heavy technical problems in realizing such high-speed drawing. One of them is a technique in which an uncured resin 12 in FIG. 3 is applied to a fiber and cured by ultraviolet irradiation or the like to form a resin coating layer. At its core is pressure coating technology (Sakaguchi, Japanese Patent Application No. 60-259874). On the other hand, in a device mechanism, a dancer device for stably winding a fiber drawn at high speed is important. The reason is as described below.

That is, in order to keep the fiber outer diameter constant,
The take-up speed is constantly fluctuating by automatic control of the rotational speed of the take-up capstan. Since the winding drum has a winding outer diameter that is not constant due to uneven winding and winding, the rotation speed also varies. In optical fiber high-speed drawing, the fiber running speed fluctuates in such a manner, and at the same time, a constant small tension (usually 1N (0.
The fiber must be wound while giving 1 g weight) or less. Furthermore, at low speed at the beginning of winding (several tens of meters / minute)
From a high speed (several hundred meters / minute).

Further, as a dancer device configured as a vibration system, a dancer device for winding a copper core wire having a small speed fluctuation and a large allowable tension cannot be diverted as it is. An arm-type device as shown in FIG. 1 is generally used as a dancer device for an optical fiber. As shown in the figure, a pulley 1 is provided at the tip of an arm 2 and an optical fiber 4 runs, while a balancer 3 for adjusting the fiber tension is provided at the other end of the arm 2. Have been. A sensor (not shown) for detecting a rotational position is attached to the rotation center shaft 5 of the arm 2.
The optical fiber 4 travels from a capstan (not shown) through a pulley of the dancer device toward a winding drum (not shown). As the rotation speed of the capstan increases and the linear speed increases, the dancer arm points downward. The sensor detects this and controls to increase the drum rotation speed. The opposite effect occurs when the linear velocity decreases. In this way, the dancer controls the rotation of the drum so as to be at a fixed position with respect to the fluctuation of the linear velocity.

[0006] At the time of drawing, the drawing speed constantly fluctuates due to the outer diameter control as described above. Further, since the drum is also eccentric due to uneven winding or the like, the dancer always receives forced vibration. In particular, the forced vibration caused by the pick-up is a main factor that governs the stability of the dancer operation. In order to follow such forced vibration, as will be described in detail later, the inertial mass of the dancer is reduced, the arm is shortened, the natural frequency is increased, and the resonance point with the forced vibration due to the drawing speed is set. It was done to prevent it. This is because the linear velocity gradually increases from a low speed, and when approaching resonance, the dancer operation becomes unstable, leading to a fiber break or the like. For this reason, it has been necessary to make the pulleys and arms as small as possible and at the same time as small as possible. A seesaw-type dancer device in which pulleys were installed at both ends of the arm and the rotation axis was placed almost at the center of the arm was effective by shortening the effective arm length. However, when the linear velocity is 120
At the present time, when it reaches 0 m / min, it is practically impossible to increase the natural frequency due to restrictions on the material and dimensions of the dancer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical fiber drawing apparatus having a dancer apparatus which solves the problem of winding instability caused by an increase in drawing speed, and a drawing method using the same.

[0008]

To achieve the above object, an optical fiber drawing apparatus according to the present invention comprises at least a take-up capstan for drawing and drawing an optical fiber, and a winding for winding the optical fiber. An optical fiber drawing device comprising a taker and a dancer device for adjusting an optical fiber drawing traveling speed between the capstan and the drum, wherein the natural frequency of the dancer device is to take an optical fiber, Alternatively, it is characterized in that it is set to be lower than the forced frequency generated by the drawing operation of the winding optical fiber.

Further, one of the drawing methods is characterized in that drawing is performed at an optical fiber drawing speed such that the forcible frequency is higher than the natural frequency of the dancer device.

[0010]

According to the present invention, the natural vibration of the dancer device is
It is set so as to be smaller than the forced vibration caused by the drawing operation of drawing or winding, and the fiber is drawn at a drawing speed or higher corresponding to the forced frequency higher than the natural frequency of the dancer. Therefore, in comparison with the related art, the present invention is different from the related art in which the natural vibration of the dancer device is set so that the forced vibration due to drawing does not exceed the resonance point.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings.

The optical fiber drawing apparatus according to the present embodiment comprises:
The feature of the dancer device portion of the optical fiber drawing device shown in FIG. 3 is that the present embodiment will be described with respect to the dancer device shown in FIG. As shown in the figure, the effective mass of the dancer device is W (= W ₁ + W ₂ , W ₁ : mass of pulley 1, W ₂ : mass of arm 2). The mass of the balancer is set to W _3. The pulley is at the position of the arm length R, and the center of gravity of the dancer is r (= (R / 2)
(2W ₁ + W ₂ ) / W) and R> r,
The fiber is under tension T. Let θ be the rotation angle of the arm, and when θ is small, the equation of motion of the dancer is expressed by the following equation (1) from the equilibrium condition of the moment about the arm rotation axis.

(Wr ² −W ₃ L ² ) d ² θ / dt ² + 2TRg θ = 0 (1) Here, g is the gravitational acceleration, L is the position of the balancer, and W ₃ L = (2WL + W ₂ ) R / 2-2T
Satisfies R. From the equation (1), the natural frequency p of the dancer is given by the following equation (2).

P = (2TRg / (Wr ² −W ₃ L ² )) ^1/2 (2) where the arm is light, the position r of the center of gravity is near R, and the moment of inertia of the balancer is If it is small, p is given by the following equation (3).

P ≒ (2T / W) ^1/2 (g / r) ^1/2 (3) As can be seen from the above equation (3), the effective mass cannot be largely changed due to the limitation of the fiber tension. Therefore, the value of r greatly affects the natural frequency p.
By drawing, a forced vibration is applied to the dancer's movement.
The effect of capstan fluctuation is great. Here, assuming that the linear velocity is v and the diameter of the capstan is D, the forced frequency f is
The following equation (4) is obtained.

F = v / πD (4) Therefore, as the linear velocity v increases, f increases.

Here, the operation of the dancer behaves as shown in FIG. 2 with respect to f / p. That is, it is understood that the dancer performs an unstable operation as the relative dancer amplitude increases. The point where f / p = 1 is the resonance point, the dancer becomes unstable, and in the worst case, the fiber is disconnected. Therefore, in order to operate the dancer below the resonance point as in the prior art with respect to the increasing linear velocity,
It was necessary to increase p, and therefore, it was necessary to reduce r in practice. It is also possible to reduce W. However, they have limitations due to dimensional constraints.

In this embodiment, the value of p is reduced in response to the increase of f due to the increase of the drawing speed, that is, the dancer is operated beyond the resonance point.
It is clear from the above equation (3) that r should be increased in order to decrease p while keeping the fiber tension T small.

The following procedure is used to draw an optical fiber using the optical fiber drawing device provided with the dancer device. (1) The optical fiber is wound on a winding drum. (2) The speed is immediately increased to a speed at which the frequency of the forced vibration is higher than the natural frequency of the dancer device. (3) Continue drawing at high speed in a steady state.

Next, the present invention will be exemplified by specific numerical values.

Here, the pulley is made of a lightweight alloy and has a mass of 0.4.
kg, arm is carbon fiber reinforced resin and weighs 0.1 kg
And the length of the arm was 1 m. The fiber tension is
0.5 N (0.05 kg weight). From the equation (3), the natural frequency p is about 1.5 s ^-1 . This corresponds to a drawing speed of 90 m / min assuming that the diameter of the capstan is 0.318 m. That is, this speed becomes the resonance point. Actually, when the drawing was performed, the dancer became unstable at a speed of about 100 m / min, but at higher speeds, the dancer operated stably.

As a problem in this embodiment, the resonance point must be exceeded by increasing the linear speed from a low speed at the beginning of drawing the fiber (several tens m / min) to a high steady drawing speed (several hundred m / min). Therefore, a phenomenon in which winding is unstable at a linear velocity corresponding to this necessarily occurs. However, in reality, in the equation (1), since various resistances due to friction or the like act as damping resistances to the movement of the dancer, the oscillation does not completely occur and the dancer does not continue to operate with being unstable.

In this embodiment, a case will be described in which the natural frequency p is further reduced and the drawing is performed at a speed higher than the drawing speed corresponding to the resonance point. More specifically, the natural frequency p is further reduced by further increasing the length R of the arm, and the oscillation is avoided by setting the resonance point below the speed corresponding to the linear speed at which the optical fiber is wound on the drum and winding. It is like that. That is, when the arm length R is 2
m, the resonance speed is about 60 m / min. About 60
drumming at m / min and increasing speed immediately,
In this case, instability could be avoided at all.

[0020]

As described above, according to the present invention,
Since the natural frequency of the dancer is designed to be lower than the forced frequency of drawing, a steady drawing is made beyond the resonance point, furthermore, the fiber is put on the drum and the resonance point is set below the speed at which winding starts Therefore, even if the linear velocity increases, the dancer does not enter an oscillation state at all, and high-speed drawing can be stably performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a dancer device.

FIG. 2 is a graph showing a behavior of a dancer operation with respect to a forced vibration.

FIG. 3 is a configuration diagram of an optical fiber drawing apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 pulley 2 arm 3 balancer 4 optical fiber 5 preform feed 6 optical fiber preform 7 carbon resistance furnace 8 wire diameter measuring instrument 9 pressure source 10 pressure regulating valve 11 exhaust 12 coating resin 13 press die 14 ultraviolet curing furnace 15 tension measurement Container 16 Capstan 17 Winding means

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C03B 37/00-37/16

Claims (2)

(57) [Claims] 1. A drawing capstan for drawing and drawing at least an optical fiber, and a winding drum for winding the optical fiber, wherein an optical fiber wire is drawn between the capstan and the drum. An optical fiber drawing device having a dancer device for adjusting a speed, wherein the natural frequency of the dancer device is lower than a forced frequency generated by an operation of drawing an optical fiber or drawing an optical fiber for winding. An optical fiber drawing apparatus characterized by being set as follows. 2. The optical fiber drawing device according to claim 1, wherein the forced frequency is drawn at an optical fiber drawing speed such that the forced frequency is higher than the natural frequency of the dancer device. Fiber drawing method.