JPH084769B2 - Coating die - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coating die for simultaneously applying two layers of low-viscosity resin to a running wire rod such as an optical fiber to be drawn.

<Prior Art> Optical fibers used for optical communication are not limited to optical glass fibers and silica glass fibers, and it is said that it is preferable to apply a plastic coating to the outer periphery of each fiber immediately after it is made into a fiber. This is to prevent the fiber strength from being degraded due to scratches on the fiber surface caused by conversion into a fiber or crack growth due to exposure to the air in the state of a bare fiber. Such a plastic layer is generally a thermosetting silicone resin or an ultraviolet curable resin (hereinafter abbreviated as UV resin).
A reactive resin that is hardened by heat or ultraviolet rays in a low-viscosity solution to form a structure at the time of application is used, and in recent years, the demand for this UV resin-coated fiber is increasing.

On the other hand, in this optical fiber coating structure, when stress is applied to the glass fiber, which is the light guide section, from the side direction, transmission loss increases. Generally, a buffer layer having a relatively low elastic modulus is provided, and a two-layer structure for supporting and dispersing a force from the lateral direction is generally adopted (for example, see JP-A-60-251153).

Conventionally, when manufacturing an optical fiber having such a two-layer structure, as shown in FIG. 3, a bare fiber 3 obtained by drawing a preform 1 in a heating furnace 2 is used, for example, in a real-life shovel 60.
Two sets of a coating die 10 and a curing device 11 as shown in Japanese Patent No. 177931 were used. That is, the bare fiber 3 obtained by drawing the preform 1 in each heating furnace was made into the double-layer coated fiber 4 by passing through the two sets of the coating die 10 and the curing device 11.

By the way, in recent years, the demand for optical fibers has increased and the demand for price reduction has increased. Therefore, improving the productivity of optical fibers has become a major issue. It is known that the temperature of the optical fiber at the time of coating is a problem in coating the coating material when increasing the manufacturing line of the optical fiber (Ap
pl.Opt.20 (23), 4023 (1981)). As a method of lowering the temperature of the optical fiber, it is conceivable to lengthen the running distance of the bare fiber in the air. For this reason, in order to increase the bare fiber's air travel distance without increasing its overall length, the two sets of coating dies 10 described above are used.
It is considered that a method of making the air-cooled length for one set of the coating die 10 and the curing device 11 instead of the two-layer coating die is preferable.

Therefore, conventionally, a two-layer coating die as shown in FIG. 4 has been used. As shown in the figure, the double-layer coating die 20 has holes 21a, 22a, and 23 through which the bare fiber 3 passes.
a having a first die 21, a second die 22 and a point 23 having a, and a reverse between the first die 21 and the point 23 and between the first die 21 and the second die 22, respectively. The conical resin storage chambers 24 and 25 are defined. That is, the point 23 is fitted to the upper side of the first die 21 and is fixed by the point fixing screw 26 to define the first resin reservoir chamber 24, and the second die 22 is the first die 21. The second resin reservoir chamber 25 is defined by being fitted to the lower side of and fixed by the die fixing screw 27. Such a die has such a recombination function because it is necessary to clean the inside of the die in some fields such as when the resin is changed or after being used for a long time. That is,
This is because, if impurities such as dust enter the die, or if the resin remaining in the die is deteriorated, if the coating is applied as it is, the strength and other characteristics of the optical fiber may deteriorate.

Then, the first die 21 is formed with first and second resin inlets 28, 29 communicating with the resin reservoir chambers 24, 25. The first die 21 and the second die 22 have a structure in which they are directly fixed to the wall surface of the holder.

<Problems to be Solved by the Invention> The overall thickness of the coating layer of the optical fiber as described above is about 70 μm on one side, and the thickness of each of the first and second layers is several tens of μm or less. Because of this, the die fiber clearance is very small.

By the way, it is quite difficult to obtain an accuracy of several .mu.m or less by using the current metal working technology, and it is difficult to obtain an accuracy of 5 .mu.m or less in cemented carbide or steel generally used as a die. Further, the clearance for fitting the first and second dies 21 and 22 is at least 10 μm or more, and even in the case of mechanical assembly, it is several μm.
m or more is required. Therefore, the first die 21 and the second die
The cores of the holes 21a and 22a of the 22 are often displaced due to processing accuracy and assembly accuracy.

If two layers are simultaneously coated in such a state, there is a problem that so-called uneven thickness occurs due to the misalignment of the axes of the first layer coating and the second layer coating.

The present invention has been made in view of these problems, and an object thereof is to provide a two-layer coating die that does not cause uneven thickness.

<Means for Solving the Problems> The structure of the two-layer covering die of the present invention that achieves the above object is as follows.
A wire die comprising first and second dies having holes through which the wire rod simultaneously applies two layers of a low-viscosity liquid resin, wherein the first die and the second die It is characterized in that it is provided with an aligning means for moving and adjusting the relative position in a direction perpendicular to the traveling direction of the wire.

In the conventional second coating, the application of the first layer is performed by a resin flow in which the wire rod pulls the resin of the first layer, a so-called pulling flow, and the pulling flow causes the wire rod to be self-aligned. Moved towards the center of the die. Then, when the wire rod that has passed through the first die enters the second die whose core is deviated by the processing accuracy or the assembly accuracy, the self-centering force acts similarly,
Since this force is generated between the applied liquid first layer and the second layer resin, it is weaker than that described above, and the thickness is often uneven without being aligned. Further, due to this self-centering force, the first layer applied without uneven thickness may have uneven thickness.

The present invention is to prevent such an inconvenience by the above-mentioned constitution, and to adjust the eccentricity when the wire rod enters the second die from the first die.

<Examples> Hereinafter, preferred examples of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a two-layer coating die of this embodiment. As shown in the figure, the two-layer coating die 120 of this embodiment is
Are holes 121a, 122a, 123a through which the bare fiber 3 passes.
Having a first die 121, a second die 122 and a point 123
And the point that the conical resin reservoir chambers 124 and 125 are defined between the first die 121 and the point 123 and between the first die 121 and the second die 122, respectively. Similarly, the second die 122 is horizontally movable with respect to the first die 121. That is, a die holding portion 121b having a diameter larger than that of the second die 122 is formed below the first die 121, and the second die 122 has the die holding portion 121b.
After being housed inside, it is supported by a die fixing screw 127 so as to be movable in the horizontal direction. Further, on the outer periphery of the lower side of the first die 121, four uneven thickness adjusting screws 130 for projecting the tip of the first die 121 into the die holding portion 121b are provided at equal intervals. The horizontal position of the second die 122 can be adjusted. In this embodiment, a second die 122 is provided as a centering means so as to be movable in the horizontal direction with respect to the first die 121, and the outer periphery of the first die 121 is abutted against the outer peripheral surface of the second die. Adjusting screw 13
0 is set. In the figure, 126 is a point fixing screw for fixing the point 122 to the first die 121, and 12
Reference numerals 8 and 129 denote first and second resin inlets communicating with the resin reservoir chambers 124 and 125, respectively, and the resin of the first layer is the first resin inlet 12
The resin of the second layer enters the second resin reservoir chamber 125 through the second resin inlet 129.

In such a two-layer coated die, the bare fiber 3 drawn and running from the top to the bottom in the drawing is the hole 1 at the point 122.
It is inserted from 22a and enters the first resin reservoir chamber 124 to apply the first layer, then enters the second resin reservoir chamber 125 from the hole 121a and exits from the hole 123a in the state where the second layer is applied. . On this occasion,
When entering the hole 121a of the first die 121, a self-centering force is exerted and centered. However, this fiber is
When it goes out from the hole 123a through the hole 123a, it is not aligned so that the hole 121a of the first die 121 and the hole 122a of the second die 122 are not aligned.
The core and must match. The cores of the holes 121a and 122a are adjusted by using the uneven thickness adjusting screw 130.
Can be carried out by moving in the horizontal direction.

Using such a two-layer coating die of this embodiment, 950 × 065 manufactured by Desoto Co. as the first layer resin, and Desoto as the second layer resin.
Two layers were simultaneously applied using a UV-curable resin 950 × 044 manufactured by the company.

First of all, 130 pieces of four uneven thickness adjusting screws were pushed in equally and the same state as that of the conventional two-layer coating device was obtained. When two layers were simultaneously applied, the uneven thickness of the light as shown in FIG. A fiber was obtained. In this optical fiber, the first layer 3a was not unevenly thickened with respect to the fiber 3, but the second layer 3b was greatly unevenly thickened.

Next, when the position of the second die 122 was adjusted using the uneven thickness adjusting screw 130 while checking the uneven thickness state by the cross section in this way, as shown in FIG. On the other hand, an optical fiber was obtained in which neither the first layer 3a nor the second layer 3b had uneven thickness.

The uneven thickness evaluation can be more easily performed by using the scattered state of the laser light when coating the optically transparent resin.

In the above embodiment, the second die 1 is used with respect to the first die 121.
Although 22 is movably provided, it goes without saying that the same effect can be obtained even if the relationship is reversed. Further, the present invention is not limited to the two-layer coating, but can be applied to the case of the multi-layer coating.

Although the two-layer coating die used for coating the optical fiber has been described in the above embodiments, it goes without saying that it can be used for coating two layers simultaneously on a wire.

<Effects of the Invention> As described above in detail with reference to the examples, by using the coating die of the present invention, the problem of uneven thickness, which has been a conventional problem, is solved, and two layers are simultaneously applied to a running wire rod. I was able to do it.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a two-layer coating die according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing test results in this embodiment,
FIG. 3 is a schematic view showing a conventional two-layer coating process, and FIG. 4 is a sectional view of a conventional two-layer coating die. In the drawing, 121 is a first die, 122 is a second die, 123 is a point, 124 is a first resin reservoir chamber, 125 is a second resin reservoir chamber, and 130 is an uneven thickness adjusting screw.

Claims (2)

[Claims] 1. A coating die comprising first and second dies each having a hole through which a wire passes, wherein the wire is coated with two layers of low-viscosity liquid resin at the same time. A coating die, comprising a centering means for moving and adjusting the relative position of the two dies in a direction perpendicular to the traveling direction of the wire. 2. A second die is provided on the first die so as to be movable in a direction perpendicular to the traveling direction of the wire rod, and a push-pull bolt provided on the first die serves as an aligning means. The two-layer coating die according to claim 1.