JP7347185B2 - Optical fiber manufacturing method - Google Patents

Description

The present disclosure relates to a method of manufacturing an optical fiber.

Patent Document 1 describes increasing the resin supply pressure to the resin coating device from a stopped state at the start of optical fiber production to a steady linear velocity. By making the relationship between the resin supply pressure and the linear velocity smaller near the steady linear velocity than on the low linear velocity side, breakage of the optical fiber due to resin pressure fluctuations is prevented.
Patent Document 2 describes applying only either a primary resin or a secondary resin at the time of drawing a base material for an optical fiber including a core doped with germanium dioxide (GeO ₂ ). There is. This prevents the resin from curing due to luminescence within the optical fiber and clogging the die of the resin coating device.

Japanese Patent Application Publication No. 2001-66476 Japanese Patent Application Publication No. 2003-226556

In such an optical fiber manufacturing method, the thickness of the primary resin coating may increase and the thickness of the secondary resin coating may decrease on the outer periphery of the glass fiber while the linear speed increases. In this case, the primary resin coating may be exposed on the surface, leading to breakage of the optical fiber.

Therefore, an object of the present disclosure is to provide an optical fiber manufacturing method that can prevent optical fiber breakage.

A method for manufacturing an optical fiber according to one aspect of the present disclosure includes:
A glass fiber is formed by heating and drawing an optical fiber base material in a heating furnace, and a first coating resin layer is applied around the glass fiber by a resin coating device, and a second coating resin layer is applied around the first coating resin layer. A method of manufacturing an optical fiber comprising:
making an offer to take over the optical fiber with a take-off device;
After the drawing and before the steady drawing, drawing the line while increasing the line speed of the line drawing until the line speed reaches the line speed during the steady drawing;
a step of performing the steady line drawing for taking the product;
Equipped with
At the start of the increase in the wire speed, the resin temperature in the resin coating device that provides the first coating resin layer is lower than the resin temperature in the resin coating device that provides the first coating resin layer during steady wire drawing. death,
In the middle of the wire speed increase, the resin temperature in the resin coating device in which the first coating resin layer is provided is increased to the resin temperature in the resin coating device in which the first coating resin layer is provided during the steady wire drawing. .

According to the present disclosure, disconnection of the optical fiber can be prevented.

FIG. 1 is a schematic configuration diagram showing an example of an optical fiber manufacturing apparatus according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram showing a part of the resin coating device. FIG. 3 is a cross-sectional view of an optical fiber in which part of the secondary resin has been applied. FIG. 4 is a diagram showing the relationship between linear velocity and resin temperature in the first coating section. FIG. 5 is a cross-sectional view of an optical fiber manufactured by the optical fiber manufacturing apparatus.

(Description of embodiments of the present disclosure)
First, embodiments of the present disclosure will be listed and described.
A method for manufacturing an optical fiber according to one aspect of the present disclosure includes:
(1) A glass fiber is formed by heating and drawing an optical fiber preform in a heating furnace, and a first coating resin layer is applied around the glass fiber using a resin coating device, and a second coating resin layer is applied around the first coating resin layer using a resin coating device. A method for manufacturing an optical fiber provided with a coating resin layer, the method comprising:
making an offer to take over the optical fiber with a take-off device;
After the drawing and before the steady drawing, drawing the line while increasing the line speed of the line drawing until the line speed reaches the line speed during the steady drawing;
a step of performing the steady line drawing for taking the product;
Equipped with
At the start of the increase in the wire speed, the resin temperature in the resin coating device that provides the first coating resin layer is lower than the resin temperature in the resin coating device that provides the first coating resin layer during steady wire drawing. death,
In the middle of the wire speed increase, the resin temperature in the resin coating device in which the first coating resin layer is provided is increased to the resin temperature in the resin coating device in which the first coating resin layer is provided during the steady wire drawing. .
According to the above method, while the line speed is low, the outer diameter of the first coating resin layer is increased by lowering the resin temperature in the resin coating device and increasing the viscosity of the first resin constituting the first coating resin layer. can be suppressed. As a result, the thickness of the second coating resin layer can be ensured, and breakage of the optical fiber can be prevented.

(2) The drawing speed during steady drawing may be 2000 m/min or more.
When the product is taken at a high line speed (that is, when the line speed during steady drawing is high), the line speed is significantly increased, especially after finishing drawing. For this reason, if the resin temperature in the resin coating device for forming the first coating resin layer is the same at low and high linear speeds, the second resin constituting the second coating resin layer may not be coated. , optical fiber breakage could occur. By applying the aspect of the present disclosure, even when the drawing speed in steady drawing is high, it is possible to suppress the breakage of the optical fiber that occurs while the drawing speed is increasing.

(3) Resin temperature in the resin coating device that provides the first coating resin layer at the start of the increase in the linear speed, and resin temperature in the resin coating device that provides the first coating resin layer during steady wire drawing. The difference is 5°C or more and 30°C or less,
A line speed of 200 m/min when the resin temperature in the resin coating device for forming the first coating resin layer is raised to the resin temperature in the resin coating device for forming the first coating resin layer during steady wire drawing. It may be more than 1500 m/min or less.
According to the above method, when the resin temperature in the resin coating device for forming the first coating resin layer is increased within this temperature range and timing (linear speed), it is possible to further suppress the breakage of the optical fiber.

(4) The glass fiber may have a diameter of 124 μm or more and 126 μm or less, and the second coating resin layer may have a diameter of 190 μm or more and 210 μm or less.
When manufacturing an optical fiber in which the thickness of the coating resin layer (the first coating resin layer and the second coating resin layer) is small, the second resin constituting the second coating resin layer is likely to break off. Therefore, by applying the aspect of the present disclosure, even when the thickness of the coating resin layer is small, it is possible to suppress the breakage of the optical fiber that occurs during the increase in linear speed.

(Details of embodiments of the present disclosure)
A specific example of a method for manufacturing an optical fiber according to an embodiment of the present disclosure will be described below with reference to the drawings.
Note that the present disclosure is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all changes within the meaning and range equivalent to the scope of the claims.

FIG. 1 is a schematic configuration diagram showing an example of an optical fiber manufacturing apparatus 1 according to an embodiment of the present disclosure.
As shown in FIG. 1, the optical fiber manufacturing apparatus 1 includes a drawing furnace 2, a resin coating device 3, a resin curing device 4, a guide roller 5, a take-up section 6, a winding drum 7, It includes a wire drawing control device 8 and a temperature control device 9. Note that the optical fiber manufacturing apparatus 1 of this embodiment is a dual coating type manufacturing apparatus that continuously applies a primary resin and a secondary resin and cures them all at once.

The drawing furnace 2 is configured to heat and soften the lower end of the optical fiber preform G using a heater. The drawing furnace 2 is an example of a heating furnace. The lower end of the optical fiber preform G is stretched downward and drawn by the tension of the pulling section 6 to form the glass fiber G1.

The resin coating device 3 is provided downstream of the drawing furnace 2 in the running direction of the glass fiber G1 (direction of arrow A in FIG. 1). The resin coating device 3 is configured to apply resin around the glass fiber G1 formed by drawing.

The resin coating device 3 includes a first coating section 3A disposed on the upstream side and a second coating section 3B disposed on the downstream side in the running direction of the glass fiber G1. The first application section 3A applies primary resin (first resin) around the glass fiber G1. The second application section 3B applies a secondary resin (second resin) around the primary resin applied around the glass fiber G1.

The resin curing device 4 is provided downstream of the resin coating device 3 in the running direction of the glass fiber G1. The resin curing device 4 is configured to harden the resin applied to the glass fiber G1 by the resin coating device 3. The resin curing device 4 is, for example, an ultraviolet irradiation device, and cures the resin by irradiating the resin with ultraviolet rays. The optical fiber G2 formed by hardening the resin is wound onto a winding drum 7 via a guide roller 5 and a winding section 6.

The drawing control device 8 controls the drawing conditions (heating temperature of the heater, feeding speed of the optical fiber preform G, drawing speed of the drawing section 6) so as to achieve a desired drawing speed (hereinafter referred to as drawing speed). , etc.). Specifically, the drawing control device 8 controls the drawing conditions so that the drawing speed increases after the drawing starts and reaches a constant drawing speed when the drawing speed reaches a constant drawing speed. Further, the drawing control device 8 outputs the drawing speed information to the temperature control device 9.

The temperature control device 9 is configured to control the resin temperature in the first coating section 3A and the resin temperature in the second coating section 3B to predetermined temperatures, respectively. The temperature control device 9 of this embodiment controls the temperature of the first application section 3A and the second application section 3B by flowing fluid inside the first application section 3A and the second application section 3B via the pipes 9A and 9B. are doing. By controlling the temperatures of the first application section 3A and the second application section 3B, the resin temperature within the first application section 3A and the resin temperature within the second application section 3B are controlled. Furthermore, the temperature control device 9 acquires line speed information from the drawing control device 8, and controls the resin temperature in the first coating section 3A to a predetermined temperature according to the line speed. Specifically, while the line speed is low, the temperature control device 9 makes the resin temperature in the first application section 3A lower than the resin temperature in the first application section 3A during steady drawing, so that the line speed increases. During the drawing, the resin temperature in the first application section 3A is raised to the resin temperature in the first application section 3A during steady drawing.

FIG. 2 is a schematic diagram showing a part of the resin coating device 3. As shown in FIG. The outer periphery of the glass fiber G1 passing through the resin coating device 3 is coated with the primary resin P flowing downstream from the flow path 30A of the first coating section 3A through the opening 32A. Then, the secondary resin S flowing downstream from the flow path 30B of the second application section 3B through the opening 32B is applied to the outer periphery of the primary resin P applied to the glass fiber G1. By the way, the resin applied to the glass fiber G1 has a characteristic that its viscosity decreases as the temperature increases. When the linear velocity is high to a certain extent, the amount of primary resin P applied to the glass fiber G1 decreases as it goes downstream from the opening 32A, as shown by the broken line in FIG. Thereby, a predetermined gap can be ensured between the opening 32B of the second application part 3B and the outer periphery of the primary resin P, and the secondary resin S can be applied satisfactorily. On the other hand, when the linear velocity is low, the amount of primary resin P applied to the glass fiber G1 remains almost unchanged even if it advances downstream from the opening 32A, as shown by the dashed line in FIG. Therefore, the gap between the opening 32B of the second applicator 3B and the outer periphery of the primary resin P becomes smaller than when the linear velocity is high. In particular, if the difference between the radius of the opening 32A of the first application section 3A and the radius of the opening 32B of the second application section 3B is small (for example, 50 μm or less), the secondary resin S cannot be sufficiently applied and the secondary resin The S coating may break midway.

FIG. 3 is a cross-sectional view of the optical fiber G2 in which a part of the secondary resin S has been applied. As shown in FIG. 3, the primary resin P is exposed on the surface of the optical fiber G2 where the application of the secondary resin S is cut off. For this reason, in the optical fiber G2, a sufficiently thick resin coating cannot be obtained particularly at the exposed portion of the primary resin P, and disconnection may occur.

The temperature control device 9 controls the resin temperature in the first application section 3A, which applies the primary resin P, to a predetermined temperature according to the linear velocity as described above. For example, the temperature control device 9 changes the temperature of the fluid according to the linear velocity, and circulates the fluid set at the changed temperature inside the first application section 3A. As a result, while the line speed is low, the resin temperature in the resin coating device 3 is lowered and the viscosity of the primary resin P is increased, thereby suppressing an increase in the outer diameter of the coating layer (first coating resin layer) caused by the primary resin P. can. As a result, the thickness of the coating layer (second coating resin layer) made of the secondary resin S can be ensured, and breakage of the optical fiber G2 can be prevented.

Next, a method for manufacturing an optical fiber manufactured using the optical fiber manufacturing apparatus 1 will be described.
First, the lower end of the optical fiber preform G is heated in the drawing furnace 2, and a part of it (a lump of glass) is allowed to fall under its own weight. Then, it passes through the resin curing device 4, is hooked onto the guide roller 5 and the take-up section 6, and is guided to the winding drum 7 (leaving step). After winding the end of the glass around the winding drum 7, drawing is performed while gradually increasing the linear speed to form the glass fiber G1 (linear speed increasing step). When the line speed reaches the line speed for steady line drawing, the increase in line speed is finished, and line drawing is performed while maintaining that line speed (steady line speed) (steady line drawing step). The optical fiber formed by constant drawing is used as a product (product production). For example, the drawing speed during steady drawing is 2000 m/min or more. The glass fiber G1 formed by drawing passes through the resin coating device 3, and two layers of resin (primary resin P and secondary resin S) are collectively coated on the outer periphery of the glass fiber G1.

FIG. 4 is a diagram showing the relationship between the linear speed and the resin temperature in the first coating section 3A. In FIG. 4, the vertical axis shows the resin temperature (° C.) or linear velocity (m/min) in the first coating section 3A, and the horizontal axis shows the elapsed time from the start of production. As shown in FIG. 4, in the steady wire drawing step, the wire speed and the resin temperature in the first coating section 3A are controlled to be a temperature _T2 and a wire speed _S2 . The temperature control device 9 controls the resin temperature in the first coating section 3A (temperature T ₁ in FIG. 4) to be the resin temperature T ₂ at the start of increasing the linear speed in the linear speed increasing process from drawing to steady drawing. The resin temperature in the first coating section 3A is controlled so that the temperature is lower than that of the first coating section 3A. Furthermore, the temperature control device 9 controls the resin temperature within the first application section 3A so that the resin temperature within the first application section 3A rises to resin temperature _T2 during the increase in linear speed. That is, when the linear velocity reaches a predetermined linear velocity (linear velocity S ₁ in FIG. 4), the temperature control device 9 starts increasing the resin temperature in the first coating section 3A, and increases the temperature of the resin in the first coating section 3A. The resin temperature is increased until the resin temperature reaches resin temperature _T2 . For example, the difference between temperature _T1 and temperature _T2 is 5°C or more and 30°C or less, preferably 5°C or more and 20°C or less. The linear speed _S1 is 200 m/min or more and 1500 m/min or less.
Note that the resin temperature may be increased at once from the resin temperature T ₁ to the resin temperature T ₂ or may be increased in multiple steps. Alternatively, it may be gradually increased as the linear velocity increases. In particular, when the difference between temperature T ₁ and temperature T ₂ is large, it is preferable to increase the temperature in multiple steps or to increase gradually as the linear velocity increases.

The glass fiber G1 coated with resin passes through a resin curing device 4, where the resin is cured and becomes an optical fiber G2. The optical fiber G2 is wound onto a winding drum 7 via a guide roller 5 and a take-up section 6. FIG. 5 is a cross-sectional view of the optical fiber 10 manufactured by the optical fiber manufacturing apparatus 1. In the optical fiber 10, a first coating resin layer 12 and a second coating resin layer 13 made of a primary resin P and a secondary resin S are formed concentrically around the outer periphery of a glass fiber 11 made of a core layer and a cladding layer. The optical fiber 10 is formed, for example, so that the diameter D1 of the glass fiber 11 is 124 μm or more and 126 μm or less, and the diameter D2 of the second coating resin layer 13 is 190 μm or more and 210 μm or less.

As described above, according to the optical fiber manufacturing method of the present embodiment, when the linear speed starts to increase, the resin temperature in the first coating section 3A in which the primary resin layer is provided is adjusted to the same level as that in the first coating section 3A during steady drawing. The temperature of the resin in the first coating section 3A is raised to the temperature of the resin in the first coating section 3A at the time of steady drawing while the drawing speed is increasing. Thereby, while the linear velocity is low, an increase in the outer diameter of the first coating resin layer 12 can be suppressed by lowering the resin temperature in the first coating section 3A and increasing the viscosity of the primary resin P. As a result, the thickness of the second coating resin layer 13 can be ensured, and breakage of the optical fiber 10 can be prevented.

Further, the drawing speed during steady drawing may be 2000 m/min or more. When picking up products at a high line speed, the line speed must be increased significantly, especially after finishing the feed. When setting the resin temperature in the first coating section 3A to the same resin temperature at low linear speed and high linear speed, the secondary resin layer may not be coated, and optical fiber breakage may occur. . According to this embodiment, even when the drawing speed in steady drawing is high, it is possible to suppress the breakage of the optical fiber that occurs while the drawing speed is increasing.

Further, the difference between the resin temperature _T1 in the first coating section 3A at the start of increasing the line speed and the resin temperature _T2 in the first coating section 3A during steady drawing is 5°C or more and 30°C or less, The line speed when raising the resin temperature in the first coating section 3A to the resin temperature in the first coating section 3A during steady drawing may be 200 m/min or more and 1500 m/min or less. When the resin temperature in the first coating section 3A is increased within this temperature range and timing, it is possible to further suppress the breakage of the optical fiber.

Further, the diameter of the glass fiber 11 may be 124 μm or more and 126 μm or less, and the diameter of the secondary coating layer 13 may be 190 μm or more and 210 μm or less. When manufacturing the optical fiber G2 in which the thickness of the coating resin layer is small, the coating of the secondary coating layer 93 is likely to break. According to the present embodiment, when manufacturing the optical fiber G2 with a small thickness of the coating layer, it is possible to suppress the coating failure of the secondary coating layer 13.

Although the present disclosure has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present disclosure. Further, the number, position, shape, etc. of the constituent members described above are not limited to those in the above embodiment, and can be changed to a suitable number, position, shape, etc. for implementing the present disclosure.

In the above embodiment, the optical fiber manufacturing apparatus 1 is a dual coating type manufacturing apparatus, but is not limited thereto. The optical fiber manufacturing apparatus 1 may be a tandem coating type manufacturing apparatus that applies and hardens resin layer by layer. In a tandem coating type manufacturing apparatus, the first coating section 3A and the second coating section 3B are arranged apart from each other. The resin curing device 4 includes a first curing section located downstream of the first application section 3A and upstream of the second application section 3B, and a second curing section located downstream of the second application section 3B. Ru. The first curing section cures the primary resin applied by the first application section 3A. The second curing section cures the secondary resin applied by the second application section 3B. Even in this case, while the linear velocity is low, the same effects as in the above embodiment can be obtained by lowering the resin temperature in the first coating section 3A and increasing the viscosity of the primary resin P.

In the embodiment described above, the temperature control device 9 controls the resin temperature in the first application section 3A and the second application section 3B by flowing the fluid inside the first application section 3A and the second application section 3B. , but not limited to. For example, the temperature control device 9 is provided with a heating device or a cooling device in a pipe that supplies resin to the first coating section 3A or inside the first coating section 3A, and controls the operation of the heating device or the cooling device. The resin temperature may also be controlled.

In the embodiment described above, the temperature control device 9 obtains the line speed information from the drawing control device 8, but the present invention is not limited to this. For example, a measuring device for measuring the linear velocity of the optical fiber G2 may be arranged and linear velocity information may be obtained from the measuring instrument.

1: Optical fiber manufacturing device 2: Drawing furnace 3: Resin coating device 3A: First coating section 3B: Second coating section 4: Resin curing device 5: Guide roller 6: Take-up section 7: Winding drum 8: Wire drawing control device 9: Temperature control device 9A, 9B: Piping 10: Optical fiber 11: Glass fiber 12: First coating resin layer 13: Second coating resin layer 30A: Channel 30B: Channel 32A: Opening 32B: Opening G: Optical fiber base material G1: Glass fiber G2: Optical fiber P: Primary resin S: Secondary resin

Claims (3)

A glass fiber is formed by heating and drawing an optical fiber base material in a heating furnace, and a first coating resin layer is applied around the glass fiber by a resin coating device, and a second coating resin layer is applied around the first coating resin layer. A method of manufacturing an optical fiber comprising:
making an offer to take over the optical fiber with a take-off device;
After the drawing and before the steady drawing, drawing the line while increasing the line speed of the line drawing until the line speed reaches the line speed during the steady drawing;
a step of performing the steady line drawing for taking the product;
Equipped with
At the start of the increase in the wire speed, the resin temperature in the resin coating device that provides the first coating resin layer is lower than the resin temperature in the resin coating device that provides the first coating resin layer during steady wire drawing. death,
In the middle of the wire speed increase, the resin temperature in the resin coating device in which the first coating resin layer is provided is increased to the resin temperature in the resin coating device in which the first coating resin layer is provided during the steady wire drawing. ,
The diameter of the glass fiber is 124 μm or more and 126 μm or less, and the diameter of the second coating resin layer is 190 μm or more and 210 μm or less,
During the linear speed increase, the application of the second coating resin constituting the second coating resin layer is not cut off midway;
Method of manufacturing optical fiber. The method for manufacturing an optical fiber according to claim 1, wherein the drawing speed during the steady drawing is 2000 m/min or more. The difference between the resin temperature in the resin coating device that provides the first coating resin layer at the start of the increase in the wire speed and the resin temperature in the resin coating device that provides the first coating resin layer during steady wire drawing is , 5°C or more and 30°C or less,
A line speed of 200 m/min when the resin temperature in the resin coating device for forming the first coating resin layer is raised to the resin temperature in the resin coating device for forming the first coating resin layer during steady wire drawing. The method for manufacturing an optical fiber according to claim 1 or 2, wherein the speed is 1500 m/min or more.

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