JPH07133140A - Resin coating device for optical fiber and its production - Google Patents

Abstract

PURPOSE:To enable the easy control of the thickness of a coating resin film by constituting the die and/or nipple of a resin coating device for an optical fiber in such a manner that the die and/or nipple is movable and that the distance from the outlet of the die to the base of the nipple is variable. CONSTITUTION:The resin coating device 21 for the optical fiber is composed of the die 22 and the nipple 23. The inside wall near the inlet 24 of the die 22 is provided with screw threads and the screw threads to be screwed to these screw threads is formed on the peripheral surface of the nipple 23 so that the die 22 and the nipple 23 are put into the state of screwing to each other. Further, the nipple 23 is rotated by a driving device 28 so that the nipple 23 is made movable parallel in a vertical direction relative to the die 22. The bare optical fiber is introduced into the die 22 from an inlet 24 thereof and a resin storage part 27 is made to travel downward to apply the coating resin liquid thereon. At this time, the nipple 23 is vertically moved by the driving device 28 to change the distance L from the outlet 25 of the die to the base of the nipple 23, by which the volume of the resin storage part 27 is changed and the film thickness of the coating resin film is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for uniformly coating and coating a resin on an optical fiber.

[0002]

2. Description of the Related Art In a conventional optical fiber manufacturing apparatus, as shown in FIG. 4, a heating furnace 1, a cooling tube 2 and a coating section 3 are vertically installed in series, and an optical fiber preform 4 is provided. The upper end is supported by the supporting and elevating member 5, and is heated by the built-in heater 6 from the lower tip inserted into the heating furnace 1.

The optical fiber 7 melt-drawn by the heater 6 enters the cooling cylinder 2 immediately below, is cooled, and is guided to the coating section 3 while traveling. In the coating unit 3, for example, the coating material is applied in the coating material tank 8 pressurized by the pressurizing device 15, then dried in the drying unit 9, and further, the coating material is applied in the coating material tank 10 and then dried. A coating layer is formed through two coating-drying steps of drying in the part 11, and the optical fiber 7 having the coating layer is formed.
Is wound around the drum 14 via the capstan 12 and the dancer rollers 13, 13.

By the way, the outer diameter of a normal bare optical fiber is 125 μm, and the outer diameter of a bare optical fiber is 250 μm. However, the outer diameter of the bare optical fiber varies depending on the size and shape of the optical fiber preform 4 or the degree of heat generated by the heater 6, and the bare optical fiber having a uniform thickness cannot be obtained. In order to solve such a problem, the spinning speed is adjusted according to the change in the outer diameter of the bare optical fiber to control the outer diameter of the bare optical fiber.

However, if the spinning speed is variable, the linear velocity of the coating portion 3 is different, so that the film thickness of the coating resin film is varied. Therefore, in order to obtain an optical fiber strand having a uniform thickness, it is necessary to newly control the film thickness. As a method of controlling the film thickness of the coating resin film of such an optical fiber element wire, for example, Japanese Patent Laid-Open No. 3-10
As disclosed in Japanese Patent No. 3342, a pressure device 1
There is one in which the film thickness is controlled by changing the pressure in the coating material tanks 8 and 10 by changing the pressure in the coating material tanks 5 and 16.

However, in such a film thickness control method, when the linear velocity is high, the ratio of the change in the film thickness of the coating resin film of the optical fiber element wire is small with respect to the change in the pressure in the coating material tanks 8 and 10. There was a problem of becoming. Therefore, at high linear velocity,
It can be said that it is difficult to control the film thickness only by adjusting the pressure in the coating material tanks 8 and 10.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of these circumstances, and provides a high-speed optical fiber strand formed with a coating resin film of uniform thickness without uneven thickness. The purpose is to get.

[0008]

In a resin coating apparatus having a die and a nipple, both or one of the die and the nipple is movable,
By using a resin coating device in which the distance from the exit of the die to the bottom of the nipple is changed, the film thickness of the coating resin film of the optical fiber strand is controlled by adjusting the distance between the die and the nipple. You can solve it.

[0009]

The resin coating apparatus and method for optical fibers of the present invention will be described in detail below. FIG. 1 shows an example of a resin coating device 21 of the present invention. The resin coating device 21 is generally composed of a die 22 and a nipple 23. The die 22 has a hollow cylindrical shape, and has an inlet 24 at an upper portion and an outlet 25 at a lower portion. Further, a screw is formed on the inner wall in the vicinity of the inlet 24, and a tapered insertion hole whose diameter is gradually reduced from the screw toward the outlet 25 is formed.

Further, the nipple 23 has an outer disk shape,
A through hole 26 is formed in the central portion thereof, and a screw that is screwed into the screw of the die 22 is formed on the peripheral surface. Dice 2
2 and the nipple 23 are screwed with each other, a conical resin storage portion 27 is formed between them, and the center of the outlet 25 of the die 22 and the through hole 26 of the nipple 23 is formed. They are arranged so as to coincide with each other on the same axis.

A driving device 28 is attached to the upper surface of the nipple 23. The driving device 28 rotates the nipple 23 itself so that the nipple 23 can move in parallel with the die 22 in the vertical direction. Therefore, the volume of the resin reservoir 27 can be changed. Further, a resin liquid supply port (not shown) is formed in the die 22, and the coating resin liquid is always supplied into the die 22 via this.

The die 22 is made of a material that is less likely to be thermally deformed, and for example, a metal material such as stainless steel or yellow steel, ceramics, engineering plastics, etc. are preferably used. Further, the size of the die 22 and the diameters of the entrance 24 and the exit 25 are arbitrary. The material of the nipple 23 is preferably the same as that of the die 22, and the size of the nipple 23 and the like can be appropriately changed so as to be in harmony with the die 22.

Next, from the bottom surface of the nipple 23 to the die 22.
Distance to the outlet 25 of the resin coating device 21 between the die 22 and the nipple 23 (hereinafter referred to as DN distance L
An example of the D-N distance adjusting device 29 for adjusting The D-N distance adjusting device 29 generally includes a resin coating device 21, a drying device 30, and an outer diameter measuring device 31.
And a calculator 32 and a drive unit 28.
A drying device 30 is installed immediately below the resin coating device 21,
An outer diameter measuring device 31 is installed immediately below the drying device 30. A calculator 32 is connected to the outer diameter measuring device 31, a drive device 28 is connected to the calculator 32, and the drive device 2 is further connected.
8 is connected to the nipple 23.

Next, such a D-N distance adjusting device 29
A method for producing an optical fiber strand will be described with reference to.
First, the optical fiber preform is melt-spun to obtain a bare optical fiber. Next, this bare optical fiber is run downward from the entrance 24 of the die 22 along the central axis of the through hole 26 of the nipple 23 to apply the coating resin liquid. Then, the bare optical fiber runs further downward and is led out from the exit 25 of the die 22. Immediately after that, the drying device 3
At 0, the resin is hardened to form an optical fiber strand.

The outer diameter of the thus-obtained optical fiber element wire is measured by the outer diameter measuring device 31 installed immediately below the drying device 30, and the result is sent to the calculator 32. The calculator 32 analyzes this result and sends a command to the drive unit 28 so that the D-N distance L is appropriate for obtaining the target film thickness. In response to such a command, the drive unit 28 operates the nipple 23 and determines the position of the nipple 23 so that the optical fiber element wire having a desired film thickness is obtained.

The examples given here are examples of the present invention, and the specific conditions can be changed as appropriate. For example, the die 22 and the nipple 23 may be moved by a piston method or the like in addition to the screw winding method as in the above example. Further, the die 22 and the nipple 23 may be inscribed in a holder having a cylindrical outer diameter or the like, and may be movable. Furthermore, the resin coating device 21
Equipped with a pressurizing function, pressure change and DN distance L
Even if the film thickness can be controlled from both sides of adjustment, it does not matter. Also, the die 22, the nipple 23
In addition, any shape that satisfies the conditions of the present invention can be adopted.

A resin coating device 21 for such an optical fiber.
In this case, since both or one of the die 22 and the nipple 23 is movable, and the distance from the outlet 25 of the die 22 to the bottom surface of the nipple 23 is changed, the resin coating device 21 is used. It is possible to obtain an optical fiber element wire having a desired film thickness even if the value is continuously changed. In other words, the spinning speed can be continuously changed while keeping the film thickness almost constant.

(Embodiment 1) The effects of the present invention will be clarified by showing concrete examples below. Resin coating device 21 shown in FIG.
Spinning at about 500 m / min with an outer diameter of 125μ
m optical fiber bare wire was obtained. Then, a UV resin was applied to this to obtain an optical fiber element wire. Further, the DN distance L immediately after the start of the experiment is set to 1, and the nipple 23 is moved so that the relative values become 0.5, 2, and 3, and the DN distance L is adjusted, and the light in each case is adjusted. The outer diameter of the fiber strand was measured by the outer diameter measuring device 31. The result is shown in FIG. From the result of FIG. 3, it is understood that the film thickness of the coating resin film can be finely adjusted by changing the DN distance L.

Example 2 Using the DN distance adjusting device 29 shown in FIG. 2, UV resin was applied to a bare optical fiber having an outer diameter of 125 μm to obtain a bare optical fiber. At this time, the spinning speed was increased to 400 m / min to 600 m / min, and at the same time, the DN distance L was changed to 1.3 to 0.7. The outer diameter of the thus obtained optical fiber is 203 μm at 600 m / min and 600 μm.
It was 197 μm at m / min.

(Comparative Example) An optical fiber element wire was obtained in the same manner as in Example 2 while keeping the DN distance L constant. The outer diameter of the optical fiber at this time was 210 μm at 400 m / min and 190 μm at 600 m / min. As described above, by adjusting the DN distance L, the film thickness of the coating resin film can be controlled even if the spinning speed is largely changed.

[0021]

As described above, the resin coating apparatus for an optical fiber and the manufacturing method thereof according to the present invention, in a resin coating apparatus having a die and a nipple, both or one of the die and the nipple are movable, Since the one that changes the distance from the exit of the die to the bottom of the nipple is used, it is possible to control the film thickness of the coating resin film of the optical fiber by adjusting the distance between the die and the nipple. You can Therefore, it is possible to obtain the effect that the spinning speed of the optical fiber can be changed during the same process without largely changing the film thickness of the optical fiber strand.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a resin coating device of the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment of a die-nipple distance adjusting device of the present invention.

FIG. 3 is a graph showing the relationship between the distance between the die and nipple and the outer diameter of the optical fiber strand.

FIG. 4 is a schematic configuration diagram showing a conventional optical fiber manufacturing method.

[Explanation of reference numerals] 21 ... Resin coating device, 22 ... Die, 23 ... Nipple,
29 ... DN distance adjusting device, 31 ... Outer diameter measuring instrument

Claims (2)

[Claims] 1. A resin coating device having a die and a nipple, wherein either or both of the die and the nipple are movable, and the distance from the outlet of the die to the bottom surface of the nipple is changed. Resin coating device. 2. A coating resin liquid is stored between a die and a nipple, the bare optical fiber is inserted into the coating resin liquid through the nipple, and a coating resin film is formed on the outer periphery of the bare optical fiber. In the method for producing an optical fiber, the film thickness of the coating resin film is controlled by changing the distance from the exit of the die to the bottom surface of the nipple.