JPH03214105A - Method and apparatus for producing optical fiber - Google Patents

Abstract

PURPOSE:To decrease the transmission loss by the irregular structures of optical fibers and to improve quality by molding the optical fibers while resonating a mouthpiece by oscillation. CONSTITUTION:While a core material which is a molding material is supplied from an extruder 7 for a core to a supplying port 1b, a clad material which is a molding material is supplied from an extruder 8 for a clad to a supplying port 1c. The mouthpiece 1 is resonated at n-wavelengths by generating the oscillation in an oscillation generator 5 by an oscillator 6. The inflow ports 1b, 1c of the mouthpiece 1 are made to coincide with the nodes of resonance and further, the contact parts of the extruding port 1a and the oscillation generator 5 with the mouthpiece 1 are preferably made to coincide with the loop part of the resonation. The flowability of the molding material in the mouthpiece 1 is improved in this way and the boundary face of the core material and the clad material is smoothed. In addition, the fluctuation in the core diameter is suppressed and the optical fiber having the low transmission loss is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention combines a core material and a cladding material supplied from two extruders using a spinneret (sometimes called a composite spinning nozzle). A method for manufacturing optical fibers by spinning and an apparatus thereof, in particular, a method for manufacturing high-quality optical fibers by improving the fluidity of molding materials (core material and crat material) in gold. and its equipment.

[Prior Art] Since the advent of optical fibers in recent years, there has been remarkable progress in technology. As a result, optical fibers have been used in a wide range of applications with low loss, for example in the field of communication systems. It is widely used as a transmission cable for transmitting information.

This optical fiber basically has a two-ton structure in which a core material is made of a polymer with a high refractive index, and a cladding material made of a polymer with a lower refractive index surrounds the core material. Generally, optical fibers with this structure are manufactured continuously using two extruders and a die. In other words, the core material that has gone through the refining and polymerization process is supplied from the core extruder to the die. On the other hand, the molten cladding material is also supplied from the cladding extruder to the die. Subsequently, the core material and cladding material are combined and spun in a spinneret to obtain an undrawn fiber, which is further imparted with toughness in the drawing process to produce an optical fiber.

By the way, there are two causes of transmission loss in plastic optical fibers (POF): inherent factors of the material itself and external factors that depend on the fiberization technology, and each of these factors can be roughly divided into absorption loss and scattering loss. be done. Here, absorption loss refers to the loss caused by the absorption of molecular vibrations by the polymer itself or metal impurities mixed into the polymer during manufacturing, while scattering loss refers to the loss caused by the scattering of incident light within the fiber. Among these losses, scattering loss due to external factors is caused by the inclusion of impurities and structural irregularities, and is particularly caused by irregularities at the interface between the core and crut and fluctuations in the core diameter. It accounts for 30 to 50% of the scattering loss or transmission loss due to structural irregularities.

[Problems to be Solved by the Invention] Conventionally, in order to reduce the transmission loss due to the above-mentioned structural irregularities, attempts have been made to make the extrusion opening in the spinneret have a special shape, and to develop advanced spinning techniques. However, at present, no satisfactory results have been obtained, and this has been considered a problem to be solved in order to improve the quality of optical fibers.

The present invention was made in view of such conventional problems, and improves quality by reducing transmission loss due to structural irregularities of optical fibers. The purpose of the present invention is to provide a method for manufacturing an optical fiber that can be carried out smoothly, and an optical fiber manufacturing device that can be easily constructed.

[Means for Solving the Problems] In order to achieve the above object, the present invention, which relates to a method for manufacturing an optical fiber, combines a core material and a crat material supplied from each extruder using a die and spins the fiber. Accordingly, in a method of manufacturing an optical fiber, the molding is performed while causing the base to resonate with vibration.

In addition, as a preferred embodiment of the present invention, a method may be employed in which molding is performed while causing resonance so that the abdomen of the resonance coincides with the position of the extrusion port in the die.

Further, as another preferred embodiment, a method may be adopted in which molding is performed while causing resonance so that the resonance node coincides with the position of the material inlet in the die.

In the invention of an apparatus for manufacturing an optical fiber by supplying molding material from an extruder to a die, at least one vibration generator is coupled to the die.

[Example] Examples of the above solution will be described below.

FIG. 1(a) is a schematic configuration diagram of an optical fiber manufacturing apparatus according to an embodiment of the present invention, FIG. 1(b) is an enlarged sectional view of section A in FIG. 1(a), and FIG. ) is an enlarged side view of the base of the device, and the curve in Figure 1 shows the displacement waveform at resonance. Figure (b) is also a bottom view.

In these drawings, ■ is a cap, and 5 is a cap member 2,
It is divided into 3.4 parts. and cap members 2, 3 and 3
．． An extrusion port 1a is provided at the joint surface with 4.

Various materials such as conventionally used metal materials, ceramics, and graphite can be used for IJ gold 1, but among these materials, materials with low vibration transmission loss at the molding temperature are recommended. It is preferable to use duralumin, titanium alloy, aluminum alloy, phosphor bronze, and graphite.Also, although the base 1 is divided into three parts, when it is composed of a plurality of members like this, may be made of the same material or may be made of different materials.

Further, the cap 1 can be subjected to various plating treatments or coating treatments for the purpose of improving wear resistance, corrosion resistance, or lowering the coefficient of friction with the molding material.

Since most parts of the cap 1 vibrate during resonance, when a conventional cast-in aluminum heater is installed, the wiring inside the heater may break due to the vibration. Therefore, it is preferable to use a far-infrared heater that can heat the base 1 without coming into contact with the base 1. In this case, make sure that the heater comes into contact only with the part that does not vibrate in the resonating base 1, that is, the resonant node, and use a screwdriver at that node to connect the metal 1 and the far-infrared heater. Just fix it.

In addition, as a heating method for the cap 1, it is also possible to use a method in which oil for temperature control is circulated inside the metal cap 1. t
It is preferable to match the position t of the node at the time of resonance of the cap 1. By doing so, it is possible to prevent the joints attached to the supply 1 and the discharge 11 from loosening due to vibration.

1b is the inflow port for the core material, and the LC beam is the inflow port for the thick material. Each material passes through this inflow port 11, and finally the core material is covered with cloud material from the extrusion port 1a. It will be pushed out in a state where the 1it inlet lb,
Ic is provided at approximately the node of the resonance in each fX gold member (Fig. 2 (a)). In this way, vibration is transmitted to the nozzles etc. that come into contact with the inlets lb and lc. The best thing to do is to try not to communicate it at all. Furthermore, in order to suppress the transmission of vibrations to the nozzle, etc., it is recommended to incorporate a cushioning material, such as a titanium alloy fiber, into the contact area between the nozzle and all the members.

On the other hand, it is preferable that the extrusion port 1a coincides with the abdomen of the resonance (Fig. 2 (a)).The abdomen of the resonance is a position where the vibration effect is large, and the extrusion port 1a should be placed here. This makes it possible to perform molding while minimizing the W friction resistance between one die 1 and the molding material.

5 is a vibration generator that gives vibration to the [1 gold 1], and is coupled to t to the extent that it can give vibration to the base 1 and make it resonate, and the vibration generator that makes the base 1 resonate is
An ultrasonic vibrator, an electrodynamic vibrator, a hydraulic vibrator, etc. can be used.

It is also possible to incorporate a vibration transmitting body between the cap 1 and the vibration generating device 5, and if the shape of the vibration transmitting body is appropriately selected, the vibration generated by the vibration generating device 5 can be incorporated. It is possible to easily increase or decrease the amplitude. In order to transmit the vibration generated by the vibration generator 5 to the cap 1 with high efficiency and easily, the contact portion between the vibration generating bag M5 and the cap 1 should be a part of the resonant IE that vibrates with the largest amplitude in the cap 1; That is, it is preferable to match the resonance region (FIG. 2(a)).

Furthermore, there is no particular limitation on the number of vibration generators coupled to the cap 1 or the number of vibration transmitters interposed between them, or if a plurality of them are coupled, the timing of vibration is adjusted and the number of vibration transmitters interposed between them is adjusted. It is necessary to prevent the resonance state from being disturbed.

6 is a light vibration generator, which generates vibration in the vibration generating bag δ5, and
Excite the metal at a frequency of 1 and cause the base 1 to resonate. Either total resonance or partial resonance is preferable.

The resonant frequency of the cap 1a is designed and manufactured to a frequency that can be tracked by the ultra-A wave oscillator when ultra-A wave vibration is used, for example. The system constantly tracks slight changes in the resonant frequency due to momentary load fluctuations until the molding material is extruded from the extrusion port 1a, and the required amount of power ( maximum output). In other words, automatic frequency tracking and automatic power control methods are adopted.

Further, as the vibration mode, in addition to longitudinal vibration, it is possible to use transverse vibration, torsional vibration, radial vibration, and flexural vibration.

Furthermore, as shown in FIGS. 3(a) and 3(b), it is also possible to provide the base 1 with a mechanism for changing the direction of vibration.

For example, L
- If the L converter 3a is used, the vibration direction can be changed at right angles. In addition, there are L-R conversion bodies.

The cap 1 is equipped with a converter such as an L-L-L converter. By doing this, the vibration transmission direction was perpendicular to the extrusion direction of the molding material in the device shown in FIG. 2, whereas in the device shown in FIG. art is i in the extrusion direction
It is possible to transmit motion.

Next, an embodiment of an optical fiber manufacturing method performed using the manufacturing apparatus described above will be described.

The core extruder 7 supplies a core material, which is a molding material, to the supply port 1b, while the cladding extruder 4118 supplies a clad material, which is a molding material, to the supply port 1c. The core material is Bocker Bonate.

Polymethyl methacrylate (PMMA), deuterated P
MMA, PMMA copolymer, polystyrene, diethylene glycol bisallyl carbonate, polycarbonate, polytrifluoroisopropyl methacrylate, polychlorostyrene, polytetrafluoroethylene, polyvinylidene fluoride, etc. can be used. Examples include base polymers, silicone, TPX, modified TPX, and nylon.

By causing the vibration generator 215 to generate vibrations using the oscillator 6, the single-cap metal fitting is caused to resonate at n wavelengths. The vibration frequency at this time can usually be selected within the range of 10H2 to 1 OM Hz, or should be extremely high in order to produce the vibration effect in a short time and to suppress excessive heat generation of the molding material. ,
It is preferable to set the frequency to OKll□ to 100K11□. Also, n-wave Gino (n in vibration is m/2 (m・
(a positive integer) (FIG. 2(a)), or preferably n<3 in order to reduce the vibration loss in the tie I. Furthermore, in order to effectively improve the fluidity of the molding material, the amplitude of the vibration applied to the single die must be between 0.1 gm and 10
It is preferable to set it to 0 μm.

Also, as explained in the device embodiment, ['' gold 1
It is preferable that the inflow meters ib and lc of the inflow meter ib and lc coincide with the resonance node, and furthermore, the extrusion ula.

And the contact part between the vibration generator 5 and the cap 1 is a resonance II.
It is preferable to match the IJ part (Fig. 2(a), Fig. 3(a, )).

]-As mentioned above, while making the cap 1 resonate, press each press 118 times7.
A core material and a cloud material are respectively supplied from 8 to form a two-layer structure in which the core material is coated with a crat material inside the nozzle 1, and the molding material is extruded from an extrusion port 1a and spun. The extruded molding material (optical fiber) has a diameter of about 31 mm, for example, and is then wound up from a take-up machine 9.
It is stretched between the mats to a diameter of about 1 l. Depending on the characteristics of the I& shape material, it may be extruded to a diameter of about 1 ms and wound without being stretched.

[Experimental Examples] Hereinafter, the results of experiments conducted using the optical fiber manufacturing method and apparatus of the present invention will be explained while comparing them with comparative examples.

[1 gold: Nozzle diameter φ3 (-1) Vibration generator, ultrasonic vibrator PZT tie molding conditions:
Resin temperature 260 ('C) Base temperature + 260 (''C) Take-up speed = 20 (■/■in) Amplitude: 11 (Hirom) Vibration mote: Longitudinal vibration resonance / 1.5 wavelength resonator (Fig. 2) (a)) Fiber diameter: φl (+s+m) Molding is performed while making the cap resonate under the two-legged condition.
The transmission loss of the molded product was measured.

Experimental Example 2 An experiment was conducted under the same conditions as in the experimental example except that the resin temperature was 245 ('C) and the mouth temperature was 245 (°C).

Comparative Example 1 An experiment was conducted under the same conditions as Experimental Example 1 except that the oscillation of the ultra-hill wave was stopped.

Comparative Example 2 An experiment was conducted under the same conditions as Experimental Example 2, except that the ultrasonic oscillation was stopped.

Table 1 shows the experimental results of Experimental Examples 1 and 2 and Comparative Examples 1 and 2.
Shown below.

Table 1 [Effects of the invention] As shown in l- below, according to the uninvented optical fiber manufacturing method, by effectively applying vibration to the 1-1 gold, the eyelet is made to vibrate (J), and its resonance is suppressed. This can be used to improve the fluidity of the molding material within the eyelet, to smooth the interface between the two core materials and the clad material, and to suppress fluctuations in the core diameter.As a result, optical fibers with low transmission loss can be manufactured. Something comes up.

Further, according to the optical fiber manufacturing apparatus of the present invention.

1 & [It is possible to improve the fluidity of the material and manufacture an optical fiber with low transmission loss, and the manufacturing method of the present invention can be carried out easily and smoothly.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1(a) is a schematic configuration diagram of an optical fiber manufacturing apparatus according to an embodiment of the present invention, and FIG. 1(b) is an enlarged cross-sectional view of section A in FIG. 1(a). Figure 2 (a) is a side view showing an enlarged view of the cap part of the device and the displacement waveform during resonance, Figure 2 (b) is a bottom view of the device, and Figure 3 (a) is the main body of the device. FIG. 2 shows an optical fiber manufacturing apparatus according to another embodiment of the invention, and FIG.
is a bottom view of the device. 1: [1 gold 18: Extrusion "11b, lc:
Inflow port 2, 3.4: mouthpiece member 5, vibration generator 21
6 = Oscillator (ultrasonic vibrator) (Ultrasonic vibrator Reden Extruder

Claims (2)

[Claims] (1) A method for manufacturing an optical fiber by combining and spinning a core material and a cladding material supplied from each extruder using a spinneret, characterized in that forming is performed while the spinneret is resonated by vibration. Method of manufacturing optical fiber. (2) An optical fiber manufacturing apparatus for manufacturing an optical fiber by supplying molding material from an extruder to a die, characterized in that at least one vibration generator is coupled to the die.