JPH11106239A - Coating device in optical fiber drawing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating device in optical fiber drawing that can coat the optical fiber with a resin more uniformly than in the conventional and can cope with the fluctuation in drawing speed of optical fiber exactly by detecting the contact between the coating resin and the optical fiber in conformity to more practical ways. SOLUTION: In this coating device, the parent material for optical fiber is melt-drawn and the resultant optical fiber (4) is passed through the resin- coating dice (100). Simultaneously, the coating resin is press-extruded in the resin-coating dice (100) to coat the optical fiber (4) and the resin-coating dice has a pressure sensor (19) for measuring the pressure extruding the coating resin embedded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber wire coating apparatus for applying a resin coating to an optical fiber obtained by melt-spinning an optical fiber preform.

[0002]

2. Description of the Related Art Conventionally, an optical fiber obtained by melt-spinning an optical fiber preform is coated with a resin for the purpose of protection and handling. The resin coating usually has a two-layer structure,
The primary coating layer is coated directly on the optical fiber to prevent the optical fiber from being damaged. Further, the secondary coating layer is provided on the primary coating layer, and is provided for the purpose of further protecting and improving handling. This resin coating is performed using, for example, a drawing apparatus as shown in FIG. That is, while the optical fiber preform 1 is melted in the heating and melting furnace 2 and the spun optical fiber 4 is drawn by the capstan 9, the optical fiber 4 is divided into the primary coating layer die 5 and the secondary coating layer while being drawn. By sequentially passing the primary resin to the primary coating layer die 5 and the secondary resin to the secondary coating layer die 8, respectively.
The optical fiber 4 is formed by laminating a primary coating layer and a secondary coating layer. This coating is performed by controlling the coating state of each coating resin by the outer diameter measuring device 3, the uneven thickness monitor 6, and the like. In the drawing, reference numeral 7 denotes a curing furnace for curing the resin, and an ultraviolet irradiation device and a heating furnace are used depending on the type of the coating resin.

Further, as shown in FIG. 4, similar resin coating can be performed by using a dual die 10 in which a primary coating layer die 5 and a secondary coating layer die 8 are integrated into one. . As shown in FIG. 5, the dual die 10 is formed by laminating a primary coating layer die 5 and a secondary coating layer die 8, and the respective resin inlets 5a,
A primary resin and a secondary resin are introduced from 8a. The inside of each die 5, 8 has a resin intake 5a, 8
The resin flow paths 5b and 8b are formed toward the insertion portions 5c and 8c of the optical fiber 4 so as to be continuous with a, and the resin for coating is extruded onto the surface of the inserted optical fiber 4. A nipple 18 for introducing the optical fiber 4 is laminated on the primary coating layer die 5. By using this dual die 10, two primary coating layers and two secondary coating layers are simultaneously formed, and the cooling distance of the optical fiber 4 required for resin coating can be extended.

The above resin coating is performed by adjusting the extrusion pressure (hereinafter referred to as resin pressure) of the coating resin in each of the dies 5, 8, and 10 so that the outer diameter of the optical fiber 4 is constant. Will be FIG. 6 is a schematic view showing an example of an apparatus configuration for that purpose. The monomer of the coating resin is stored in a resin tank 11, and the coating resin is released by a gas pressure from a gas cylinder 12 connected to the resin tank 11. The dies 5 (8, 10) are fed under pressure through the resin supply path 13. At this time, the gas pressure is controlled by the dies 5 in the resin supply path 13.
It is measured by the pressure sensor 14 disposed immediately before (8, 10). An outer diameter measuring device 3 is arranged downstream of the dies 5 (8, 10), and measures the outer diameter of the optical fiber 4 after resin coating (hereinafter, referred to as coating outer diameter). Then, the measured values of the pumping gas pressure and the coating outer diameter are sent to the controller 15, and the controller 15 adjusts the pumping gas pressure via the regulator 16 so that the coating outer diameter of the optical fiber 4 falls within a predetermined range. To control. In addition, the code | symbol 17 in a figure is a pressure meter. As described above, the resin coating is applied to the optical fiber 4 simultaneously with the drawing.

[0005]

By the way, the outer diameter of the optical fiber preform 1 may fluctuate due to various factors such as uneven heating, but the outer diameter of the optical fiber 4 also changes accordingly. The outer diameter is adjusted by changing the drawing speed. At the same time, the outer diameter of the coating of the optical fiber 4 fluctuates with the change of the drawing speed, so that the resin pressure of the coating resin is adjusted to keep the outer diameter of the coating constant. However, as shown in FIG. 6, the pressure sensor 14 is provided outside the dice 5 (8, 10),
The resin pressure at the actual contact position between the coating resin and the optical fiber 4 is not measured, and further, as shown in FIG. 5, the resin flow paths 5b and 8b are thin and complicatedly bent. Therefore, the flow state of the coating resin in the resin flow paths 5b and 8b is often not uniform. In such a state, it is difficult to precisely adjust the resin pressure of the coating resin particularly with respect to the fluctuation of the drawing speed of the optical fiber 4, and in extreme cases, the increase in the micro bending loss such as the increase in microbending loss. In some cases, the characteristics were reduced.

The present invention has been made in view of the above circumstances, and detects a more actual contact state between a coating resin and an optical fiber, thereby forming a more uniform optical fiber resin coating than before. It is another object of the present invention to provide an optical fiber wire drawing and coating apparatus capable of accurately coping with fluctuations in the drawing speed of an optical fiber.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical fiber obtained by melt-spinning an optical fiber preform according to the present invention by inserting the optical fiber into a resin coating die and drawing the optical fiber in the resin coating die. An apparatus for applying a resin coating to an optical fiber by extruding a coating resin under pressure, wherein the resin coating die includes a built-in pressure sensor for measuring an extrusion pressure of the coating resin. This is achieved by an optical fiber line coating and coating apparatus. According to the above-mentioned optical fiber wire coating apparatus, the resin pressure at the substantial contact point of the coating resin with the optical fiber is detected, and the coating conditions are controlled based on the detected pressure. And a more uniform and stable resin coating than before can be achieved.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an optical fiber coating apparatus according to the present invention. The main components of the optical fiber wire coating and coating apparatus of the present invention are the same as those shown in FIG. 3 or FIG. 4, and a fusion heating furnace 2 for melting the optical fiber preform 1 and an optical fiber 4 are drawn. Capstan 9, heating melting furnace 2 and capstan 9
Are provided with a primary coating layer die 5 and a secondary coating layer die 8, or a dual die 10, a curing furnace 7, an outer diameter measuring instrument 3, a thickness deviation monitor 6, and the like. The optical fiber 4 is inserted into the primary coating layer die 5 and the secondary coating layer die 8 or the dual die 10 in the course of drawing, and the primary coating layer and the secondary coating layer are supplied by the coating resin supplied to each die. A coating layer is formed sequentially. The resin forming the primary coating layer and the secondary coating layer is not particularly limited, and primary resins and secondary resins conventionally used for coating optical fibers can be used. For example, U
When producing the V element wire, a UV curable urethane acrylate resin is suitably used for both the primary resin and the secondary resin. When a silicon / nylon core wire is produced, a thermosetting or UV-curable silicone resin is suitably used as a primary resin, and a nylon resin is suitably used as a secondary resin.

According to the present invention, in the above configuration, the primary coating layer die 5, the secondary coating layer die 8 or the dual die 10 has a built-in pressure sensor for measuring the resin pressure of the coating resin. Features. In the following description, the dice will be referred to as a dice with a built-in pressure sensor. Then, instead of the conventional resin pressure measured just before the dice (see FIG. 6), the coating outer diameter of the optical fiber 4 is controlled based on the resin pressure measured by the pressure sensor. FIG. 1 is a schematic diagram showing an apparatus configuration for that purpose, but the basic configuration is the same as that shown in FIG. That is, the resin tank 11, the gas cylinder 12, the regulator 16, the pressure meter 17, the outer diameter measuring device 3, the control device 1
The coating resin stored in the resin tank 11 is pumped to the pressure sensor built-in die 100 through the resin supply pipe 13 by the gas pressure of the gas cylinder 12. The optical fiber 4 is inserted into the dice 100 with a built-in pressure sensor.

FIG. 2 shows an example of a pressure sensor built-in die 100 suitable for the present invention. The dice 100 with a built-in pressure sensor is similar to the dual dice 10 shown in FIG. 5, except that the primary coating layer die 5 and the secondary coating layer die 8 are stacked, and the primary coating layer die 5 A nipple 18 is laminated thereon to be integrated, and a pressure sensor 19 is provided therein. The coating resin is supplied from the respective resin inlets 5a, 8a, and the resin flow paths 5a,
8a through nozzle 5d. The resin is extruded from 8d onto the surface of an optical fiber (not shown) inserted into the die, and the resin pressure at that time is measured by the pressure sensor 19. Here, the pressure sensor 19 may be disposed at any position along the resin flow paths 5b and 8b as long as the pressure sensor 19 does not disturb the flow of the coating resin. A subtle change in the contact state with the resin for use can be detected immediately, and it is possible to respond quickly and accurately to fluctuations in the outer diameter of the optical fiber.
Therefore, as shown in the figure, the pressure sensor 19 is preferably provided in the vicinity of the nozzles 5d and 8d from which the coating resin is extruded, particularly in the downstream of the nozzles 5d and 8d in the moving direction of the optical fiber.

The measured value of the resin pressure by the pressure sensor 19 is sent to the control device 15 and is treated as a parameter for controlling the outer diameter of the coating of the optical fiber 4 as in the prior art. However, the measured value of the resin pressure by the pressure sensor 19 is closer to the optical fiber 4 than the measured value by the pressure sensor 14 provided immediately before the dice 5 (8, 10) as shown in FIG. Since the measured resin pressure is a more accurate and accurate resin pressure, the resin coating can be performed accurately even when the drawing speed fluctuates.

In the above description, the pressure sensor built-in die 1
In the present invention, as shown in FIG. 3, a dice for the primary coating layer and a dice for the secondary coating layer are used, and the pressure sensor 19 is attached to each die. It is also possible to adopt a configuration in which it is incorporated.

[0013]

As described above, according to the optical fiber wire coating and coating apparatus of the present invention, the resin pressure at the substantial contact point between the coating resin and the optical fiber is detected, and the coating conditions are determined based on the detected pressure. Because of the control, it is possible to accurately cope with fluctuations in the drawing speed of the optical fiber and the like, and a more uniform and stable resin coating than before can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part showing an embodiment of an optical fiber wire quote coating apparatus according to the present invention.

FIG. 2 is a sectional view of an essential part showing an example of a dice with a built-in pressure sensor suitable for the optical fiber wire coating and coating apparatus according to the present invention.

FIG. 3 is a schematic diagram for explaining the overall configuration of the optical fiber line quote coating apparatus.

FIG. 4 is a schematic diagram showing another configuration example of the optical fiber wire quote coating apparatus.

FIG. 5 is a sectional view of a main part showing an example of a resin coating die (dual die) used in the optical fiber wire drawing and coating apparatus.

FIG. 6 is a schematic diagram of a main part showing a configuration of a conventional optical fiber wire quote coating apparatus.

[Explanation of symbols]

 Reference Signs List 3 outer diameter measuring device 4 optical fiber 5 primary coating layer die 5a resin inlet 5b resin flow path 5d nozzle 8 secondary coating layer die 8a resin intake 8b resin flow path 8d nozzle 11 resin tank 12 gas cylinder 13 resin supply pipe 15 Control device 19 Pressure sensor 100 Die with built-in pressure sensor

Claims (1)

[Claims] An optical fiber obtained by melt-spinning an optical fiber preform is inserted into a resin coating die and drawn, and the resin for coating is extruded under pressure in the resin coating die to form a resin on the optical fiber. An apparatus for applying a coating, wherein the resin coating die has a built-in pressure sensor for measuring an extrusion pressure of the coating resin.