JPS593413B2 - Optical fiber manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing optical fibers for communications.

Optical fibers are used in practical applications, such as by heating and drawing glass laminated foam to produce bare optical fibers, applying a coating to the bare optical fibers, making them into cables, and laying them.

By the way, it is necessary to guarantee the minimum strength of the optical fiber at each stage of making an optical fiber into a cable, installing it, and using it after installation. Therefore, in the past, a constant load was applied to the optical fiber strand or bare wire for a certain period of time, or it was reduced to a smaller diameter, either continuously or discontinuously during the manufacturing process of the optical fiber strand or bare wire. Fifteen screening tests have been conducted in which tensile stress is generated on the surface of an optical fiber by bending, and low-strength portions whose strength is below a set value are cut and removed in advance. However, this screening test is a type of fatigue test, and there is a risk that flaws on the surface of the optical fiber may grow by conducting the screening test. In view of the above, an object of the present invention is to provide a method for manufacturing an optical fiber in which a screening test is performed to prevent the formation of defects on the surface of the optical fiber.

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

In FIG. 1, the preform 52 is connected to the feeder I
It is sent out from the VC and heated in the electric furnace 3. 11 is a control device for the feeding device 1, and 12 is a measuring device for measuring the feeding amount.

31 is a density adjustment device, and 32 is a recorder.

The heated preform 2 is drawn by a capstan 30 and a roller 61Vc to become a bare optical fiber 4. The dimensions of this bare optical fiber 4 are measured by an outer diameter measuring device 5. Immediately after that, plastic is coated and baked on the bare optical fiber 4 by a coating device 91 and a resin curing heater 92, resulting in a 35-piece optical fiber 10. The coating device 9 is composed of the coating device 91 and the heater 92Vc. Reference numeral 62 denotes a pedestal device for the capstan roller 61, which is fed back by the outer diameter measuring device 5.

63 is a rotation unevenness meter, and 64 is a meter.

The capstan roller 61, the control device 62, the rotation unevenness meter 63, and the meter 64 constitute the take-off device 6.
This optical fiber wire 10 is once wound onto a take-up reel 72, and then wound onto a torque reel 73K in a continuous process. The torque reel 73 is rotated with a constant torque by a torque motor 74, and generates a constant tensile stress in the optical fiber strand 10. These reels 72, 73
is placed in an anhydrous chamber 71 covered with an acrylic plate, for example, so that this screening test is conducted in an anhydrous atmosphere. In this embodiment, the anhydrous chamber 71
Dry Ar was poured into it. Anhydrous chamber 71, reel 72, 7
3. The motor 74 constitutes the screening test device 7. The optical fiber wire 10 that has undergone this screening test is wound onto a take-up reel 81 which is rotated by a motor 82K. The take-up reel 81 and the motor 82 constitute the take-up device 8.
In FIG. 1, the optical fiber wire wound onto the take-up reel 81 after the screening test is further coated to become a cored optical fiber wire, which is then made into a π cable. , these steps will be omitted. Next, we conducted an experiment to confirm the effectiveness of the above method, which will be described below. First, defects are created in advance on the surface of the optical fiber wire drawn as described above.
A low-intensity optical fiber wire of approximately 16001 nm was prepared. A comparison was made between a case where this optical fiber wire was subjected to a conventional screening test and a case where the above-mentioned screening test according to the present invention was conducted. First, the approximately 1,600 m long optical fiber described above was heated at a temperature of 23°C.
, 80 (LR.H. (relative humidity)) by applying a tensile stress of 7007 using the conventional method. When the test was carried out a total of 10 times, the number of breaks was 8 times in total.In this first test, it broke and was divided into two parts (the 750m side).
A test was conducted using the method of the present invention. Specifically, as explained in FIG. 1, the screening test device was covered with an acrylic plate, dry Ar was poured into it, and the temperature was 23°C and 10% R. H. The test was repeated with a tensile stress of 700 V in a dry atmosphere at (relative humidity). As a result, as shown in Figure 3, 2
Only a break occurred at a certain point. Therefore, as a result of this experiment, it was found that the screening test using the method of the present invention reliably reduces the strength deterioration of the optical fiber. As described above with respect to the embodiments, according to the present invention, it is possible to perform a screening test on bare optical fibers or bare optical fibers without causing strength deterioration. In the above embodiment, a dry gas is fed to create an anhydrous atmosphere, but it is also effective to create a vacuum state or to maintain the temperature at the lowest possible temperature below the liquid N2 temperature.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a method according to an embodiment of the present invention, and FIGS. 2 and 3 are schematic diagrams showing the state of fracture of an optical fiber strand after an experiment. 1... Feeding device, 2... Glass preform, 3... Heating device, 4...
Optical fiber bare wire, 5... Outer diameter measuring device, 6...
...Take-up device, 7... Screening test device, 8... Winding device, 9...
- Coating device, 10... Optical fiber wire.

Claims (1)

[Claims] 1. A step of heating and drawing a glass lariform to make a bare optical fiber, a step of coating the bare optical fiber to obtain a bare optical fiber, and a step of producing a bare optical fiber by heating and drawing the bare optical fiber. 1. A method for manufacturing an optical fiber comprising the step of performing a screening test by generating tensile stress on the surface of the fiber, characterized in that the screening test is performed in an anhydrous atmosphere.