JPS609972B2 - Optical fiber spinning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to multi-component glasses that have a relatively low processing temperature, unlike quartz-based glasses, or
The present invention relates to a manufacturing method for making a strong optical transmission fiber from a glass preform made of glass shown in No. 207 and having a predetermined refractive index distribution in the radial direction.

Conventionally, when spinning a preform having a relatively low processing temperature as described above, a preform 12 is fed at a constant speed into a cylindrical heater 11 as shown in FIG. 1, heated to a high temperature by the heater 11, and pulled. I made Fiber 13.

After this, the fiber is coated with a primary coat of thermosetting resin or the like before the capstan touches the guide reel. Of course, there is a relationship here: cowpi-V: pre-V D: preform diameter, d: fiber diameter, V: feeder speed, and tension speed v.

0 However, in such a method, the preform easily deforms in the region of broad temperature distribution in the longitudinal direction, and becomes a fiber when stretched.
It turns into fibers before the surface temperature gets that high.

When fibers made under these spinning conditions are subjected to mechanical tests such as tensile tests, only weak fibers that break from the surface are obtained.

If you try to raise the temperature of the heater 11 to increase the strength of the fiber by threading, the glass will become too soft (<0), and slight tension fluctuations and vibrations will affect the softened part of the glass, causing fiber flea d. Fluctuations increase.

The object of the present invention is to provide a means for forming a preform into a high-temperature melt paper yarn in order to overcome these drawbacks.

In the present invention, a crucible with a hole in the bottom (made of platinum or quartz) made of a material that does not react with glass and has high temperature strength is heated to a high temperature, and a preform is fed into the crucible, and the heat from the crucible with a hole in the bottom is heated. By pulling the melted glass and making it into fibers, the surface temperature of the glass to be made into fibers can be raised, and then it can be rapidly cooled.

Even if the melting temperature is increased, the change in the ambient temperature after prevention is substantially small, so the temperature difference becomes larger as the melting temperature is increased, and a rapid cooling effect can be obtained. In this way, when fibers are made by heating molten paper thread shells at high temperatures and then rapidly cooling them, the glass fibers become stronger.This means that when making multi-component glass fibers, the fibers made by the double crucible method are the same. This is evidenced by the fact that it is much stronger than fibers made using core-clad glass using the rod-in-tube method (ie, the conventional method).

By the way, with soda-lime glass fiber (150 French), the former method yields 6 to 6k9, while the latter method yields only 1 to 2k9.The present invention aims to increase such strength. This is aimed at the conditions of spinning at high temperature and rapid cooling.

The present invention will be explained below using two examples. The present invention is based on the use of a crimp collar with a hole in the bottom (also referred to as the single collar method), and is not limited to these two examples. In FIG. 2, a cylindrical carbon heater 21 housed in a carbon capsule 24 in a metal container 25 includes a water-cooled electrode 21'' and a carbon support 21.
′ is energized and generates heat.

Here, high-frequency induction heating may be performed by appropriately selecting the furnace structure, refractory material, shape, etc. A long pipe-shaped crucible 27 made of quartz glass is provided inside this heater, and its tip 27' is narrowed to make the outlet smaller.

A preform 22 is fed into this at a constant speed 27
′, the fiber is melted and spun at a speed v to form a fiber 23
get. In addition, in order to prevent air from entering this container and burning carbon and metals, use an inert gas such as N2.
Perform gas seal at A and B.

Immediately thereafter, a primary coat is applied to the paper fiber 23.

In FIG. 3, a cylindrical heater 31 made of platinum or the like is placed in a metal container 35, and electricity is supplied thereto through a water-cooled electrode 31'' and a conductor 31' to generate heat.

Inside this heater is a platinum crucible 37 to be heated.
is provided, and its tip 37' is constricted so that the outlet becomes small. Here, too, high-frequency conductive heating may be performed directly on 31 or 37 excluding 31 by appropriately selecting the furnace structure, refractory material, shape, etc.
is fed at a constant speed V, melted and spun at 37', and the fiber 33 is pulled at a constant speed. In addition,
If you do not want to introduce oxygen into this container, you can fill it with an inert gas such as N2. In particular, in order to heat only the crucible to a high temperature and cool the preform and fiber parts, it is effective to provide water cooling coils and boxes 39A and 39B. It is effective to maintain the high temperature near the brim by providing a quartz glass 38' and a quartz glass 38'' on the outside thereof. Next, one embodiment of the present invention will be described.
Core is Cs20-B203-Si02 Clad is B20
After cleaning and smoothing the surface of the 8th side preform made of 3-Si02 glass, it was graded into fibers with a diameter of 150 mm using the method shown in Figure 1 and the method shown in Figure 2.・Fiber was obtained by coating.

The heater used here is made of carbon with 2 ribs ◇ (inner diameter)
In the method shown in FIG. 2, a quartz crucible was used as a heater with a height of 10 cm and a quartz glass tube with an inner diameter of 14 and an outer diameter of 16, with the outlet at the bottom narrowed. When the temperature of the heater itself was 1,350 qo in the case of Fig. 1 and 150,000 qo in the case of Fig. 2, the variation in linear strain was the smallest and yarns could be woven with the same tension.

The fiber wire obtained in this way was further extruded and coated with 0.9 mosquitoes. A tensile test was conducted on the core wire.

The conventional method shown in FIG. 1 produces an average of 1.1k9 (0.8-1.
7k9), whereas the method of the present invention shown in FIG. 2 yielded good results with an average breaking load of 3.5k9 (3.0 to 4.5k9). Furthermore, when the same experiment was conducted using the methods shown in Figures 2 and 3, it was found that the results shown in Figure 3 were no worse than those in Figure 2.

The water linings 39A and 39B in Fig. 3 are used to suppress the rise in the ambient temperature of the preform and immediately after spinning, but compared to the case without water cooling, the temperature difference when the yarn is melted and graded increases to increase the rapid cooling effect. It is considered that there were no results.

According to the present invention, since the paper yarn conditions are high temperature and rapid cooling, strong fibers can be obtained.

Furthermore, since the outlet of the crucible is fixed, glass fibers can be stably obtained at the center of the high temperature zone, resulting in fibers that have undergone a uniform thermal history in the circumferential direction. Furthermore, even if the preform to be fed is slightly tilted, it is corrected within the crucible, making it easy to install the preform.

[Brief explanation of drawings]

FIG. 1 shows a conventional spinning method, and FIGS. 2 and 3 show one method of the present invention. In Figure 1, 11G heater, 12 preform, 1
3 is fiber, 14 is carbon capsule, 15 is S
US container, 1 6A and B are N2 gas introduction holes, 11' is a bar, and 12'' is a telephone pole. In Figure 2, 21 is a heater, 22 is a breform, 23
is fiber, 24 is carbon capsule, 25 is SU
S container, 26A and B are N2 gas introduction holes, and 27 is a crucible. In Fig. 3, 31 is a heater, 32 is a preform, 33 is a fiber, 35 is an SUS container, 37 is a platinum crucible, 38, 38', 38'' is a heat shield, 39'A,
B is a water-cooled container. Zoo Diagram 2 Diagram 3 Diagram

Claims (1)

[Claims] 1. In a manufacturing method for making fiber by spinning a preform rod having a predetermined refractive index distribution in the radial direction, the outside of a crucible with a bottom hole with a narrowed outlet is heated, and the preform is gradually introduced into the crucible. An optical fiber spinning method characterized by inserting the fiber into a crucible, melting it at a high temperature near the bottom of the crucible, and pulling and spinning the molten preform that falls from the bottom hole.