JPH0538017Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an apparatus for coating an optical fiber with a resin immediately after being drawn, and particularly relates to a coating apparatus capable of adjusting thickness deviation using a resin pressurization method.

[Prior art and its problems]

Conventionally, an open die has been used to coat the optical fiber with resin immediately after drawing, but this method has limitations in terms of coating speed and bubble entrainment, so recently a method using a pressurized die has been used. It is being considered.

The pressurizing cap applies resin coating by squeezing molten resin around the optical fiber from between a die and a nipple coaxially arranged with the running optical fiber, and the resin coats the running optical fiber with good followability. This method has advantages such as being able to increase the coating speed and reducing entrainment of bubbles.

However, when the pressurizing die as described above is used, there is a problem that uneven thickness of the coating layer tends to occur.
In order to eliminate this uneven thickness, it is effective to adjust the relative position between the die and the nipple, but since it is necessary to maintain a liquid-tight state between the die and the nipple with a pressurized mouthpiece, the relative position adjustment range between the two is that there are few
In addition, because the resin is press-fitted from one place into the cylindrical resin passage between the die and the nipple, the flow velocity differs between the injection port side and the opposite side, resulting in uneven resin flow in the circumferential direction. Therefore, it has the disadvantage that adjusting thickness unevenness is extremely difficult and time consuming.

[Means for solving the problems and their effects] In order to solve the problems of the prior art as described above, the present invention involves extruding molten resin around an optical fiber running between a coaxially arranged die and a nipple. In an optical fiber coating apparatus equipped with a pressurizing cap, the pressurizing cap is provided with two or more resin pressurizing ports spaced apart in the circumferential direction, and each resin pressurizing port is capable of adjusting the resin pressure or flow rate at that position. It is characterized in that a resin supply system is connected.

With this configuration, the flow rate (flow velocity) distribution in the circumferential direction of the resin flowing between the die and nipple can be changed by adjusting the resin pressure or flow rate at each resin injection port. Unbalanced thickness can be adjusted without changing the position.

〔Example〕

FIG. 1 shows a pressurizing mouthpiece used in the device of the present invention. This pressurizing base 11 has a die 13 and a nipple 14 coaxially arranged around a traveling optical fiber 12. Dice 13 and nipple 14
are integrally combined so that their relative positions do not change, and a cylindrical resin passage 15 is formed between them. The pressurizing mouthpiece 11 also has two resin pressure inlets 16a communicating with the resin passage 15;
16b are provided at 180° intervals. As shown in FIG. 2, the two resin injection ports 16a and 16b are connected to molten resin supply sources 17a and 17b, respectively, and the molten resin therein is supplied to the pressurizing device 1, respectively.
It is designed to be pressurized by 8a and 18b.

The resin in the molten resin supply sources 17a, 17b pressurized by the pressurizing devices 18a, 18b flows into the resin passage 15 from the resin pressure inlets 16a, 16b due to the pressure, and forms a cylindrical flow therein. Then, it is squeezed out from between the die 13 and the nipple 14 and coated around the optical fiber 12. At this time, if uneven thickness occurs in the coating layer 19,
By adjusting the pressure of the pressurizing device 18a or 18b,
Thickness unevenness can be reduced by lowering the resin pressure at the resin injection port closer to the thick wall side, increasing the resin pressure at the resin pressure port closer to the thin wall side, or by using both in combination.

FIG. 3 shows another embodiment of the invention. This device includes a quantitative supply device 20 that supplies resin from a molten resin supply source 17 at a constant flow rate;
A split flow path 21 that splits the resin into two and supplies them to the two resin pressure inlets 16a and 16b of the pressurizing mouthpiece 11, respectively, and a flow rate adjustment valve 22 installed in one of the paths after the split flow. There is. As the metering supply device 20, a metering discharge pump or the like can be used.

In this device, a constant flow rate of resin is supplied from the quantitative supply device 20, so when the opening degree of the flow rate adjustment valve 22 is adjusted, the resin flow rate at the resin pressure inlets 16a and 16b will be relatively increased or decreased, resulting in uneven thickness. Adjustments will be made. In other words, this device can adjust thickness deviation while keeping the coating thickness (average wall thickness in the circumferential direction) constant, and is therefore suitable for adjustment when thickness deviation occurs for some reason during operation.

FIG. 4 shows yet another embodiment of the present invention. This device automatically minimizes thickness deviation by adding a feedback control system for thickness deviation to the device shown in FIG. That is, a known thickness unevenness detector 2 using forward scattering of a laser is placed below the pressurizing mouthpiece 11.
3 to detect the uneven thickness of the coating layer online, and send the detected value to the flow rate adjustment valve 2.
2, the opening degree is adjusted in the direction of reducing uneven thickness.

In the above-mentioned embodiment, an example was explained in which two resin pressurization ports were provided in the pressurizing mouthpiece, but three or more resin pressurization ports may be provided. In that case as well, it is desirable that the resin injection ports be provided at equal angular intervals in the circumferential direction.

Further, in the above embodiment, the coating of a single-core optical fiber has been described, but the present invention can also be applied to a case where five-core or ten-core optical fibers arranged in a tape-like manner are coated all at once.

[Effect of idea]

As explained above, according to the present invention, two or more resin pressure inlets are provided in the pressurizing mouthpiece, and each resin pressure inlet is connected to a resin supply system that can adjust the resin pressure or flow rate at that position. By adjusting the resin pressure or flow rate at the resin injection port, there is an advantage that uneven thickness can be easily adjusted while the die and nipple are fixed.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of the pressurizing die used in the present invention, and Figs. 2 to 4 are system diagrams showing embodiments of the optical fiber coating apparatus of the present invention using the pressurizing die. It is. 11... Pressure cap, 12... Optical fiber, 13
...Dice, 14...Nipple, 16a, 16b
...Resin pressure inlet, 17a, 17b, 17... Resin supply source, 18a, 18b... Pressure device, 19...
Coating layer, 20... Constant supply device, 22...
...Flow control valve.

Claims (1)

[Scope of utility model registration request] In an optical fiber coating device equipped with a pressurizing die that presses out molten resin around an optical fiber running between coaxially arranged dies and nipples, the pressurizing die has two or more resin pressures spaced apart in the circumferential direction. 1. An optical fiber coating device, comprising an inlet, and each resin pressure inlet is connected to a resin supply system capable of adjusting the resin pressure or flow rate at that position.