JPH07229820A - Optical fiber screening apparatus - Google Patents

Abstract

PURPOSE:To provide an optical fiber screening apparatus in which even such optical fiber as coated thinly or coated with a hard material can be screened as prescribed without causing disconnection. CONSTITUTION:Specific physical features are provided so that an optical fiber 5 is buffered on the outer circumferential surface of each pulley 21' in a roller 2 for applying tensile stress. In other words, elastic modulus is set at 5kg/mm<2> and the Shore A hardness is set at 50 or below on the outer circumferential surface of each pulley 21'. The pulley 21' comprises a pulley body 22 and a surface material 23 on the outer circumferential surface thereof. Elastic modulus or Shore A hardness is preferably specified as mentioned above for the surface material 23 and the thickness of the surface material is preferably set equal to or thicker than the outer diameter of optical fiber while taking account of the fact that the optical fiber sinks into the surface material 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber screening apparatus, and more particularly to an optical fiber screening apparatus having a structure for applying tensile strain to an optical fiber between a plurality of pulleys in a tensile strain applying roller. .

[0002]

2. Description of the Related Art Since an optical fiber is made of a glass material, it shows a characteristic as a so-called brittle material in which a crack or crack is generated by a slight stress when the surface or its vicinity has a scratch or a bubble.

The above optical fiber is coated with plastic or the like while paying close attention to the drawing.
If the coating is perfect, an optical fiber can be obtained whose strength can be stably maintained high. However, it is still not possible to manufacture a perfect product, and in some cases, a low strength portion may be present. The low strength portion of this optical fiber needs to be removed. Therefore, a method of removing the low-strength portion by applying 0.5% elongation for 1 second over the entire length of the optical fiber being manufactured is generally adopted, and this is called screening.

FIG. 2 shows an example of a conventional apparatus for carrying out the above-mentioned screening, which comprises a pay-out roller 1, a tensile strain applying roller 2, a take-up roller 3 and a take-up roller. 5 is
After being fed from the feeding roller 1, it is wound around the two pulleys 21 and 21 of the tensile strain applying roller 2 and run between these pulleys, and at that time, the optical fiber is loaded with a load W applied to one pulley (lower side). Tension to apply tensile strain (0.5% elongation / 1 second),
After that, it was taken up by the take-up roller 3 and further taken up by the take-up roller 4. The two pulleys 21 and 21 also function as dancer pulleys whose relative distance is variable.

By the way, it is known that an optical fiber breaks at a tension of about 6 kgf, which is 6 to 7% on average.
It can be said that it will be cut by the growth of. Therefore, the screening level described above is 1 /
Although it is as small as about 10, when used as an optical cable, the elongation applied to the optical fiber is at most 0.
Since it is designed to be 2% or less, practically sufficient strength can be guaranteed. In the case of an ordinary optical fiber, the probability of breaking due to the above-described screening is about once every several tens of kilometers.

[0006]

However, an optical fiber having a special coating, for example, a coated thin optical fiber having a thinner coating thickness than an ordinary optical fiber, or an optical fiber having a particularly hard coating material is described above. When the screening was carried out in this manner, disconnection frequently occurred in the pulley portion of the tensile strain applying roller, and a phenomenon in which it could not pass through the screening line occurred. As a result of intensive investigations by the inventors regarding the cause, when the optical fiber is wound around the two pulleys of the tensile strain applying roller and tension is applied between the pulleys, the contact pressure of the optical fiber to the outer peripheral surface of the pulley is increased. It has been found that local stress concentration occurs in the optical fiber itself without even stress being applied over the entire contact surface of the optical fiber, where is about a half circumference per pulley, and the resulting damage is too great. Such stress concentration on the optical fiber occurs because the buffering effect of the coating is insufficient.

Therefore, the screening level is lowered in the optical fiber having the above-mentioned special coating (generally, the tension applied to the optical fiber between the pulleys is lowered).
It is necessary to carry out screening with such treatments, and therefore, sufficient strength guarantee cannot be obtained.

The present invention has been made in view of the above-mentioned state of the art, and an object thereof is an optical fiber having a thinner coating thickness than an ordinary optical fiber or an optical fiber having a hard coating material. Even so, it is an object of the present invention to provide an optical fiber screening apparatus that can perform screening as specified without causing disconnection.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides means for giving specific physical properties so that a buffering action for an optical fiber can be obtained at the outer peripheral surface of each pulley in a tensile strain applying roller. I took it.

That is, the elastic modulus of the outer peripheral surface of each pulley of the tensile strain applying roller was set to 5 kg / mm ² or less.

The above-mentioned pulley is 5 kg / mm ^{2 in} itself.
Although it may be formed so as to have the following elastic modulus, it is desirably composed of a pulley main body and a surface material provided on the outer peripheral surface of the pulley main body, and the elastic modulus of the surface material is as described above. What is specified is preferable, and it is preferable that the thickness of the surface material is equal to or more than the outer diameter of the optical fiber in consideration of sinking of the optical fiber into the surface material.

On the other hand, as another means, a shore A on the outer peripheral surface of each pulley of the tensile strain applying roller is used.
The hardness was 50 or less.

The above-mentioned pulley may be formed so as to have a Shore A hardness of 50 or less, but it is preferably composed of a pulley main body and a surface material provided on the outer peripheral surface of the pulley main body. , Its surface material is Shore A
It is preferable that the hardness is specified as described above, and that the thickness of the surface material is equal to or larger than the outer diameter of the optical fiber in consideration of the optical fiber sinking into the surface material.

According to the optical fiber screening apparatus having the above means or, when the optical fiber is wound around the two pulleys of the tensile strain applying roller and a tension is applied between the pulleys, the optical fiber is moved to the pulley 1. The pulley surface over about a half circumference surface is buffered under the condition that the elastic modulus is 5 kg / mm ² or less or the Shore A hardness is 50 or less, and even stress is shared by the entire contact surface between the pulley and the optical fiber. Routine screening (0.5% elongation / 1 second) can be performed without unnecessary disconnection.

[0015]

FIG. 1 shows a preferred embodiment of the optical fiber screening apparatus according to the present invention. Since the same parts as those in FIG. 2 are designated by the same reference numerals, refer to the above description concerning FIG. However, the explanation is omitted here.

In this embodiment, each pulley 21 ', 21' of the tensile strain applying roller 2 is composed of a pulley body 22 and a surface material 23 provided on the outer peripheral surface of the pulley body 22, and the surface material 23 has elasticity. The rate is 5 kg / mm ² or the Shore A hardness is 50 or less.

FIG. 3 shows a situation in which the optical fiber 5 is brought into contact with the outer peripheral surface of the surface member 23 on the outer peripheral surface of the pulley main body 22 by applying tension (pressure). According to this, the physical properties are specified as described above. When the optical fiber 5 is depressed by about half (t ₂ ) in the radial direction with respect to the surface material 23, the load can be shared over the widest area, and even if the optical fiber 5 is further depressed, the load area increases. There wasn't. The surface material 23 is the optical fiber 5
The thickness (t ₁ ) is equal to or larger than the outer diameter of the optical fiber 5, and even if the optical fiber 5 is submerged, the surface material portion exists below the optical fiber 5 by the radius of the optical fiber, and thereby the cushioning effect can be exerted.
However, in this embodiment, considering the compression of the entire surface material 23 due to the load, the thickness (t ₁ ) of the pulley surface material 23 is set to 2 to 3 mm with respect to the optical fiber outer diameter of about 250 μm.

FIG. 4 shows that the optical fiber has a coating outer diameter φ of 180.
2 shows the correlation between the elastic modulus of the pulley surface material 23 and the 1% proof average passage length of the optical fiber when the μm UV core is screened by the above-mentioned screening apparatus. According to it, the elastic modulus is 5 kg /
soft vinyl chloride, urethane acrylates exceeding mm ^2,
Nylon has a passage length of less than 100 m, whereas silicone rubber with elastic modulus of 5 kg / mm ² or less (both high elasticity and low elasticity) and UV curable silicone acrylate have a passage length far exceeding 10,000 m. I was able to get Therefore, from the practical point of view, the elastic modulus is 5 kg / mm ² .

FIG. 5 shows that the optical fiber has a coating outer diameter φ of 180.
2 shows the correlation between the hardness of the pulley surface material 23 and the 1% proof average passage length of an optical fiber when a UV core wire of μm is screened by the above screening apparatus. According to it, the shore hardness A is 5
For soft vinyl chloride, urethane acrylate, and nylon that exceed 0, the passage length is less than 100 m, whereas for silicone rubber (both high elasticity and low elasticity) with a shore hardness A of 50 or less, or UV curable silicone acrylate. A passage length far exceeding 10,000 m could be obtained. Therefore, the Shore hardness A is 5 from the practical viewpoint.
It is set to 0 or less.

A specific example of screening will be further described below.

(Specific Example 1) First, in a target optical fiber, a resin coating is applied to an optical fiber element wire having an outer diameter φ of 125 μm, and a normal optical fiber having a final outer diameter φ of 240 μm is coated with a resin. A small diameter optical fiber having a diameter φ of 160 to 180 μm was prepared. When this optical fiber was screened by the conventional apparatus shown in FIG. 2, the optical fiber was frequently broken. On the other hand, in the apparatus of this embodiment shown in FIG. 1, an elastic body having an elastic modulus of 5 kg / mm ² or less was used for the surface material 23, and the above-mentioned small-diameter optical fiber was screened. I was able to pass by.

(Example 2) As a thermal optical fiber, a polyimide-coated optical fiber (Young's modulus of polyimide: 280 kg
/ Mm ² ) was used for screening with the conventional apparatus shown in FIG. 2, the optical fiber was frequently broken. On the other hand, when the heat-resistant optical fiber was screened with the same apparatus of this example as in Example 1, it was possible to pass through the ordinary screening.

[0023]

According to the optical fiber screening apparatus of the present invention as described above, even if an optical fiber having a thinner coating thickness than an ordinary optical fiber or an optical fiber having a hard coating material is used, the optical fiber is not broken. It can be said that the intended purpose of providing an optical fiber screening device that can perform screening as specified can be achieved, and that the practical effect is great.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of an optical fiber screening device according to the present invention.

FIG. 2 is an explanatory diagram showing an example of a conventional optical fiber screening device.

FIG. 3 is an explanatory view showing a contact relationship between a pulley and an optical fiber in a tensile strain applying roller according to an embodiment of the present invention.

FIG. 4 is a characteristic diagram showing the correlation between the elastic modulus of the pulley surface material and the 1% average proof passage length of the optical fiber.

FIG. 5 is a characteristic diagram showing the correlation between the hardness of the pulley surface material and the 1% proof average passage length of the optical fiber.

[Explanation of symbols]

 1 Rolling-out roller 2 Roller for applying tensile strain 3 Pulling roller 4 Winding roller 5 Optical fiber 21 'Pulley 22 Pulley body 23 Surface material

Claims (6)

[Claims] 1. In an optical fiber screening apparatus having a structure in which tensile strain is applied to an optical fiber between a plurality of pulleys in a tensile strain applying roller, the elastic modulus of the outer peripheral surface of each pulley is set to 5 kg / mm ² or less. Characteristic optical fiber screening device. 2. The optical fiber screening device according to claim 1, wherein the pulley comprises a pulley body and a surface material provided on the outer peripheral surface of the pulley body, and the elastic modulus is specified in the surface material. 3. The optical fiber screening apparatus according to claim 2, wherein the thickness of the surface material is equal to or larger than the outer diameter of the optical fiber. 4. An optical fiber screening apparatus having a structure in which tensile strain is applied to an optical fiber between a plurality of pulleys in a tensile strain applying roller, wherein the Shore A hardness of the outer peripheral surface of each pulley is 50 or less. Optical fiber screening device. 5. The optical fiber screening apparatus according to claim 4, wherein the pulley comprises a pulley body and a surface material provided on the outer peripheral surface of the pulley body, and the Shore A hardness is specified in the surface material. 6. The optical fiber screening apparatus according to claim 5, wherein the thickness of the surface material is equal to or more than the outer diameter of the optical fiber.