JPH0752255B2 - Loose tube core wire manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a loose tube core wire in which an optical fiber is housed in a tube together with a jelly, and is applied to a communication transmission body of a communication cable or a power cable. Is what is used.

[Conventional technology]

In a loose tube core wire in which one or more glass optical fibers are loosely housed in a tube made of a thermoplastic resin (for example, polyamide, PBT, etc.), the excess length of the optical fiber in the tube ( The amount by which the axial length of the optical fiber is made longer than the axial length of the tube) is one of the factors that determine the characteristics of the loose tube core wire.

That is, if the excess length is too large, the optical fiber will buckle in the tube, and conversely if the excess length is too small, the loose tube core wire winding or communication, in the process of manufacturing each cable of power, The optical fiber receives lateral pressure.

Since both the buckling and the lateral pressure lead to the deterioration of the transmission loss of the optical fiber, in the production of the loose tube core wire, the following extra length adding method has been conventionally adopted. There is.

(A) As shown in FIG. 2, a method of increasing the feeding speed of the optical fiber 4 from the feeding machine 3 to obtain an extra length than the extrusion speed of the tube 2 extruded from the tube extrusion head 1 of the extruder. .

(B) As shown in FIG. 3, a caterpillar 5 fitted to the outer peripheral surface of the tube 2 containing the optical fiber 4 and a capstan for winding the tube 2 containing the optical fiber 4 on the loose tube core wire production line. 6 is provided, the take-up speed of the caterpillar 5 is made lower than the take-up speed of the capstan 6, and the back tension is applied only to the tube 2 in the process from the position of the caterpillar 5 to the position of the capstan 6 (the optical fiber 4). Is not directly taken up by the caterpillar 5, so no back tension is applied).

(C) As shown in FIG. 4, a first cooling water tank 7 and a second cooling water tank 8 are provided in the loose tube core manufacturing line, and the water temperature of the second cooling water tank 8 is set to the water temperature of the first cooling water tank 7. A method of obtaining a surplus length by utilizing the gradual contraction of the tube 2 by making it lower.

[Problems to be Solved by the Invention]

The above method (a) (b) for giving an extra length to the optical fiber 4
Has a problem that the feeding speed of the optical fiber 4 and the take-up speed of the caterpillar 5 and the capstan 6 need to be precisely controlled, which increases the equipment cost. Further, the method (a) is, in principle, the optical fiber 4 It is extremely difficult to control the back tension to zero unless the back tension is set to zero when sending the sheet, and even if such control is performed, the extra length will be localized. Becomes uneven, increasing or decreasing,
There was a problem of causing deterioration of transmission loss.

Further, the above method (c) obtains an extra length only by contraction of the tube 2, but when there is no filling in the tube 2 and it is air (in the case of an air core), the optical fiber 4 is used.
When back tension is applied to the delivery of, in principle, the extra length cannot be obtained even if the tube 2 contracts.
When a highly viscous jelly is put in the tube 2, even if a back tension is applied to the delivery of the optical fiber 4,
When the tube 2 and the optical fiber 4 reach a certain distance from the tube extrusion head 1, the tube 2 and the optical fiber 4 are integrated with each other through the jelly, the back tension is interrupted at that time, and the contraction of the tube 2 that occurs thereafter is the same as the excess length of the optical fiber 4. Becomes

However, it is not preferable to use a highly viscous jelly for a loose tube core wire. Therefore, if a low viscous jelly is used, it becomes a mode similar to that of the air core, and a surplus length cannot be obtained.

In this way, the material of the tube 2, the type of jelly, the presence / absence of back tension, etc. affect the extra length,
There was a problem that the materials used lacked versatility.

In view of the above problems, the present invention utilizes a contraction of a tube, accommodates a low-viscosity jelly, and sends it while applying back tension to an optical fiber to obtain a desired extra length. It is an object to provide a method for manufacturing a wire.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, a method for manufacturing a loose tube core wire of the present invention is a looseness utilizing the shrinkage of a tube material for accommodating an optical fiber together with a jelly having a low viscosity in a tube extruded by an extruder. In the method for manufacturing a tube core wire, a loose tube core wire manufacturing line is provided with a mechanism for feeding back tension of an optical fiber, and changing the position of the breaking mechanism to control the excess length of the optical fiber. To do.

The optical fiber back tension blocking mechanism uses a rotation guide body for bending the loose tube core wire in a substantially U-shape or a capstan for winding the loose tube core wire.

[Action]

While the loose tube core passes through the back-tension shutoff mechanism, which is an almost inverted U-shaped curved running path or capstan, the back tension of the optical fiber disappears due to the frictional force between them and the back tension shut-off mechanism. Then, the shrinkage amount of the tube material becomes the excess length of the optical fiber as it is.

The shrinkage of the tube material is larger as it is closer to the tube extrusion head of the extruder, and a large extra length can be obtained by placing the back tension blocking position near the extrusion head, so change the position of the back tension blocking mechanism. , Control the excess length of the optical fiber to a required value.

〔Example〕

The method of the present invention will be described with reference to the drawings showing the outline of an apparatus for carrying it out.

The same parts as those in the conventional example are designated by the same reference numerals.

As shown in FIG. 1, a tube extrusion head 1 of an extruder for a tube 2 (for example, made of a thermoplastic resin such as polyamide or PBT), a feeder 3 while applying a back tension to an optical fiber 4, a first cooling The water tank 7, the second cooling water tank 8, the winding machine 9 and the feeding machine 3 (not shown)
Of the loose tube core wire including a tube shaft center support device provided in the extrusion head 1 for introducing the optical fiber 4 from the above into the tube 2 and a device for injecting the low viscosity oil-based jelly into the tube 2 and the like. First in the production line
The optical fiber 4 passing through the cooling water tank 7 and the loose tube core wire W containing jelly are provided with three rotation guide bodies (for example, rollers, pulleys, etc.) 10 and 11, which form a substantially U-shaped curved traveling path. It is made to bend along 12.

Further, although not shown, instead of the rotation guide body 11,
It may be a capstan for winding the loose tube core wire W.

Therefore, while the winding machine 9 is actuated, the loose tube core wire W is taken along the curved traveling path of the rotary guides 10, 11, 12 while the optical fiber 4 hung in the sending machine 3 is pulled.
Back tension disappears.

In the case of a capstan, the loose tube core W is drawn by the frictional force between the loose tube core W and the winding cylinder due to the driving rotation of the winding cylinder, and the loose tube core W is sent out from the capstan by the pulled amount. The back tension applied to the optical fiber 4 in W by the feeder 3 has disappeared.

Therefore, the rotation guide body or the capstan serves as a back tension blocking mechanism of the optical fiber, and the contraction amount of the material of the tube passing through the second cooling water tank 8 after that position appears as the extra length of the optical fiber.

Since the amount of shrinkage of the material of the tube 2 is larger as it is closer to the tube extrusion head 1, a larger extra length is obtained as the position of the back tension blocking mechanism is closer to the extrusion head 1. By changing the amount, it is possible to control the required extra length amount.

Next, an experimental example is shown.

Loose tube core Tube material: PBT Tube size: Inner diameter 1.5 / Outer diameter 2.5mm Number of optical fiber cores: 4 cores Jerry: Low viscosity oil system Optical fiber back tension: 5g Back tension blocking mechanism: Rotating guide [Effects of the Invention] The present invention has the following effects.

(A) Since the optical fiber can be manufactured with the back tension applied, it is possible to stably manufacture the loose tube core wire.

(B) Since the required extra length can be obtained by changing the position of the back tension blocking mechanism, the extra length can be controlled extremely easily.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for carrying out a method for manufacturing a loose tube core wire according to the present invention, and FIGS. 2, 3, and 4 are explanatory views of a conventional optical fiber surplus length imparting method. is there. 1 ... Tube extrusion head, 2 ... Tube, 3 ...
Feeder, 4 ... Optical fiber, 7 ... First cooling water tank,
8 …… Second cooling water tank, 10,11,12 …… Rotating guide, W ……
Loose tube core.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideo Suzuki Hideo Suzuki 1440 Rokuzaki, Sakura City, Chiba Fujikura Electric Co., Ltd. Sakura Factory (56) References JP-A-1-196010 (JP, A) JP-A 64-13106 (JP, A) JP-A-62-209406 (JP, A) JP-A-61-129608 (JP, A) JP-A-61-112111 (JP, A) Actual development-JP-A 64-26718 (JP, U)

Claims (3)

[Claims] 1. A method of manufacturing a loose tube core wire, which comprises utilizing shrinkage of a tube material for accommodating an optical fiber together with a jelly having a low viscosity in a tube extruded by an extruder, wherein ,
A method for manufacturing a loose tube core wire, comprising: providing a blocking mechanism for feeding back tension of an optical fiber, and changing a position of the blocking mechanism to control a surplus length of the optical fiber. 2. The method for manufacturing a loose tube core wire according to claim 1, wherein a rotation guide body for bending the pulling direction of the loose tube core wire into a substantially inverted U shape is used for the back tension blocking mechanism of the optical fiber. 3. The method for manufacturing a loose tube core wire according to claim 1, wherein a capstan for winding the loose tube core wire is used for the back tension blocking mechanism of the optical fiber.