JPH05310446A - Method for manufacturing optical fiber core wire - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for manufacturing an optical fiber core wire capable of preventing resin residue from accumulating on the end face of the crosshead on the die exit side. [Structure] A gas seal box 13a is provided in two stages so as to entirely cover the end face 4a of the crosshead 2 on the die outlet side.
13b is provided. Each gas seal box 13a, 13b
Inert gas is supplied to the inside from the gas supply valves 14a and 14b. In this state, the optical fiber element wire 1 is passed through the nipple 3 of the crosshead 2, and the nipple 3 and the die 4
An optical fiber core wire 7 is obtained by coating the optical fiber element wire 1 with the thermoplastic resin 6 supplied from the resin flow path 5 between At this time, the die outlet side of the crosshead 2 is pressurized with an inert gas in the gas seal box 13a to suppress the accumulation of resin dust on the die outlet side end surface 4a of the crosshead.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber core wire manufacturing method for manufacturing an optical fiber core wire by passing an optical fiber wire through a crosshead and coating the surface of the optical fiber wire with a resin. Is.

[0002]

2. Description of the Related Art An optical fiber core is manufactured by forming an optical fiber wire having a primary coating made of thermosetting silicone or ultraviolet curable resin on the outer periphery of an optical fiber immediately after spinning, and using a thermoplastic resin such as nylon. Was carried out by extrusion coating with a uniaxial extrusion molding machine.

FIG. 2 shows an apparatus for carrying out a conventional optical fiber core wire manufacturing method. That is, conventionally, the nipple 3 in which the optical fiber strand 1 is incorporated into the crosshead 2 is used.
The optical fiber core wire 7 is obtained by covering the inside with the thermoplastic resin 6 supplied from the resin flow path 5 between the nipple 3 and the die 4, and passing the optical fiber core wire 7 through the water tank 8 for cooling. It was done by doing. In this case, the inlet of the nipple 3 is partitioned by an annular lid 9, and the nipple 3 has a port 10
Is provided, a vacuum pump 11 is connected to the port 10, the inside of the nipple 3 is evacuated, and the thermoplastic resin 6 is brought into close contact with the optical fiber element wire 1. Reference numeral 12 is a hopper that supplies the crosshead 2 with an extruded material made of a thermoplastic resin.

In this case, the coating diameter of the thermoplastic resin 6 is the inner diameter of the die 4, the resin pressure (supply amount), and the optical fiber strand 1.
The take-up speed (usually, the take-out speed is adjusted by feeding back the outer diameter output of the laser outer diameter measuring device to the optical fiber core take-up capstan). Further, the adhesiveness between the optical fiber element wire 1 and the thermoplastic resin 6 is substantially determined by the resin temperature and the degree of vacuum in the nipple 3 (that is, adjustment of the vacuum pump 11).

[0005]

However, when the surface of the optical fiber element wire 1 is coated with the thermoplastic resin 6 by the crosshead 2 as described above, the thermoplastic resin 6 is applied to the die exit side end surface 4a along the die exit edge portion. Since the residue of the resin 6 is accumulated and adheres to the surface of the optical fiber core wire 7, the optical fiber core wire 7 has a poor external appearance and cannot be used.

An object of the present invention is to provide a method of manufacturing an optical fiber core wire which can suppress the accumulation of resin residue on the end surface of the crosshead on the die exit side.

[0007]

Means for Solving the Problems To explain the means of the present invention for achieving the above object, the present invention is to pass an optical fiber strand through a crosshead, coat the surface of the optical fiber strand with a resin, and apply an optical fiber. In the method of manufacturing an optical fiber core for manufacturing a fiber core, the optical fiber core is manufactured while pressurizing a die outlet side of the crosshead with a gas.

[0008]

As described above, when the optical fiber core wire is manufactured while pressurizing the die outlet side of the crosshead with gas, it is possible to suppress the accumulation of resin dust on the end face of the die outlet side.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an apparatus for carrying out the method of manufacturing an optical fiber according to the present invention. The parts corresponding to those in FIG. 2 described above are denoted by the same reference numerals.

In the apparatus of this embodiment, the gas seal boxes 13a and 13b are provided in two stages so as to entirely cover the die exit end surface 4a of the crosshead 2. Each of the gas seal boxes 13a, 13b is provided with gas supply valves 14a, 14b and exhaust ports 15a, 15b for controlling the supply pressure of the inert gas to be supplied therein, and pressure gauges 16a, 16b. .. Hopper 12
An N ₂ gas introduction port 17 is provided in the.

In the present embodiment, however, an inert gas such as N ₂ gas is introduced into the gas seal boxes 13a, 13b and the opening of the exhaust ports 15a, 15b is controlled to control the gas seal boxes 13a, 13b. The optical fiber element wire 1 is coated with the thermoplastic resin 6 by the crosshead 2 while controlling the pressure of the inert gas in 13b. By doing so, the die outlet side of the crosshead 2 can be pressurized with an inert gas, and thereby the residue of the thermoplastic resin 6 can be prevented from accumulating on the die outlet side end surface 4a. Therefore, the appearance failure of the optical fiber core wire 7 can be prevented from occurring. In particular, when an inert gas is used as the pressurizing gas, the die exit side end surface 4a of the crosshead 2 can be sealed with the inert gas, and the debris of the thermoplastic resin 6 is temporarily accumulated on the die exit side end surface 4a. However, the oxidation (carbonization) of the dregs of the thermoplastic resin 6 can be prevented, and also from this point, the appearance defect of the optical fiber core wire 7 can be minimized.

Further, an inert gas such as N ₂ gas is introduced into the nipple 3 and the hopper 12 from the ports 10 and 17 to prevent outside air from entering. By doing so, it is possible to prevent the appearance defect of the optical fiber core wire 7 from occurring due to the entry of foreign matter with the outside air.

Table 1 shows Example 1, Example 2, and Example 3.
And comparative conditions of Comparative Example 1 and Comparative Example 2 and experimental results are shown in comparison. The extrusion speed at this time is
It was 100 m / min.

[0014]

[Table 1] As shown in Table 1, under the conventional manufacturing conditions (Comparative Example 1, Comparative Example 2), the appearance of the optical fiber core wire 7 was not good, but the manufacturing conditions of the present invention (Example 1, Example 2, In Example 3), almost no unevenness was observed on the surface of the optical fiber core wire 7, and the appearance of the optical fiber core wire 7 could be improved.

[0015]

As described above, in the method for manufacturing an optical fiber core wire according to the present invention, the optical fiber core wire is manufactured while the die outlet side of the crosshead is pressurized with gas.
It is possible to suppress the accumulation of resin residue on the end surface of the die outlet side. Therefore, according to the present invention, it is possible to prevent the appearance defect of the optical fiber core wire from occurring due to the adhesion of the resin residue.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of an apparatus for carrying out the method of manufacturing an optical fiber according to the present invention.

FIG. 2 is a vertical sectional view showing a conventional optical fiber core manufacturing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical fiber element wire, 2 ... Crosshead, 3 ... Nipple, 4 ... Die, 4a ... Die exit side end surface, 5 ... Resin flow path, 6 ... Thermoplastic resin, 7 ... Optical fiber core wire, 8 ... Water tank, 9 ... Lid, 10 ... Port, 12 ... Hopper, 13a,
13b ... Gas seal box, 14a, 14b ... Gas supply valve, 15a, 15b ... Exhaust port, 16a, 16
b ... Pressure gauge, 17 ... N ₂ gas introduction port.

Claims (1)

[Claims] 1. An optical fiber strand is passed through a crosshead,
A method for manufacturing an optical fiber core wire by coating a resin on a surface of the optical fiber core wire to manufacture an optical fiber core wire, wherein the optical fiber core wire is manufactured while pressurizing a die outlet side of the crosshead with a gas. A method for manufacturing an optical fiber core wire, which comprises: