JP4360850B2 - Optical fiber manufacturing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical fiber manufacturing apparatus, and more particularly, to an optical fiber manufacturing apparatus capable of performing stable optical fiber outer diameter control even when a base material temperature fluctuates.
[0002]
[Prior art]
Conventionally, a heating furnace, a base material feeding means for feeding the base material into the heating furnace, an optical fiber drawing means for drawing the optical fiber from the base material softened by heating in the heating furnace, and an outer diameter of the optical fiber drawn from the heating furnace are measured. There is known an optical fiber manufacturing apparatus including an optical fiber outer diameter measuring unit that performs an optical fiber outer diameter measurement unit and a base material feed rate control unit that controls a base material feed rate based on a measured value of the outer diameter of the optical fiber (for example, a patent document). (See 1)
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-1347
[Problems to be solved by the invention]
In the conventional optical fiber manufacturing apparatus, it is assumed that the change in the outer diameter of the optical fiber sufficiently follows the change in the feed rate of the base material.
However, when the base material temperature in the heating furnace decreases due to a decrease in the environmental temperature or an increase in the base material feed amount, the viscosity of the base material increases. Changes will not follow enough. Then, hunting occurs and there is a problem that the outer diameter of the optical fiber deviates from the target value in terms of vibration.
Accordingly, an object of the present invention is to provide an optical fiber manufacturing apparatus capable of performing stable optical fiber outer diameter control even when the base material temperature fluctuates.
[0005]
[Means for Solving the Problems]
In a first aspect, the present invention provides a heating furnace, a base material feeding means for feeding a base material to the heating furnace, an optical fiber drawing means for drawing an optical fiber from the base material softened by heating in the heating furnace, and the heating An optical fiber outer diameter measuring means for measuring the outer diameter of the optical fiber drawn out of the furnace, a base material feed speed control means for controlling a base material feed speed based on the measured outer diameter of the optical fiber, and the heating furnace or An optical fiber comprising temperature measuring means for measuring a temperature of a base material in a heating furnace, and control timing adjusting means for adjusting a control timing for controlling the base material feeding speed based on a temperature measurement value. Providing manufacturing equipment.
In the optical fiber manufacturing apparatus according to the first aspect, the temperature of the heating furnace or the base material in the heating furnace is measured, and the control timing for controlling the base material feed rate is adjusted based on the measured temperature value. As a result, even if the viscosity of the base material fluctuates due to a change in the base material temperature in the heating furnace, and the followability of the change in the outer diameter of the optical fiber with respect to the change in the feed rate of the base material fluctuates, the change in the followability is controlled. The base material feed speed can be controlled by adapting the timing. Therefore, occurrence of hunting and the like can be prevented, and stable optical fiber outer diameter control can be performed.
[0006]
In a second aspect, the present invention provides the optical fiber manufacturing apparatus configured as described above, wherein the control timing adjustment means sets a control timing for each first hold time in the first temperature measurement value, and In the second temperature measurement value lower than the temperature measurement value, the control timing is set for each second hold time longer than the first hold time.
In the optical fiber manufacturing apparatus according to the second aspect, when the temperature of the heating furnace or the base material in the heating furnace decreases, the control timing for controlling the base material feed rate is lengthened. As a result, even if the base material viscosity in the heating furnace decreases and the base material viscosity increases, the follow-up of the change in the outer diameter of the optical fiber with respect to the change in the base material feed rate is reduced. The base material feed speed can be controlled by adapting the timing. Therefore, occurrence of hunting and the like can be prevented, and stable optical fiber outer diameter control can be performed.
[0007]
In a third aspect, the present invention provides the optical fiber manufacturing apparatus configured as described above, wherein the control timing adjusting means has a standard hold time of C [s], a constant greater than A, and a temperature measurement value of T1 [° C.]. When the standard temperature measurement value is T0 [° C.], the hold time is Δt [s],
Δt = C / {A ^{(T1-T0) / 100} } (1)
An optical fiber manufacturing apparatus is provided that is set by the following.
When the inventors of the present invention diligently studied, when the hold time Δt is determined by the exponential function of the deviation “T1-T0” of the temperature measurement value T1 from the standard temperature measurement value T0, the variation in the base material temperature in the heating furnace is caused. It has been found that the base material feed rate can be controlled by adapting the control timing to the fluctuation in the followability of the change in the outer diameter of the optical fiber with respect to the change in the base material feed rate.
[0008]
In a fourth aspect, the present invention is characterized in that, in the optical fiber manufacturing apparatus configured as described above, the standard hold time C = 50 [s], the constant A = 4, and the standard temperature measurement value T0 = 1950 [° C.]. An optical fiber manufacturing apparatus is provided.
When the inventors of the present invention diligently researched,
Δt = 50 / {4 ^{(T1-1950) / 100} } (2)
By determining the hold time Δt, the control timing is adapted to the change in the followability of the change in the outer diameter of the optical fiber with respect to the change in the feed rate of the base material due to the change in the base material temperature in the heating furnace. It was found that the feed rate can be controlled.
[0009]
In a fifth aspect, the present invention provides the optical fiber manufacturing apparatus configured as described above, wherein the base material feed rate control means maintains the current base material feed rate when the outer diameter measurement value is within a predetermined dead zone. The base material feed speed is increased or decreased when the outer diameter measurement value is outside the dead zone and within a predetermined limit range, and a warning is issued when the outer diameter measurement value is outside the limit range. A fiber manufacturing apparatus is provided.
In the optical fiber manufacturing apparatus according to the fifth aspect, when the outer diameter measurement value is within a predetermined dead zone, it can be estimated that the outer diameter does not go out of the limit range without controlling the base material feed speed. Therefore, the current base material feed speed is maintained. Further, when the outer diameter measurement value is outside the dead zone and within the predetermined limit range, the outer diameter may go out of the limit range unless the base material feed speed is controlled, so the base material feed speed is increased or decreased. When the outer diameter measurement value is out of the limit range, a warning is given because a thick or thin optical fiber has been manufactured to an unacceptable level.
[0010]
In a sixth aspect, the present invention provides the optical fiber manufacturing apparatus configured as described above, wherein the base material feed speed control means is configured to transmit light having a standard outer diameter R1 when a base material having a diameter R0 is fed at a base material feed speed V0. When the outer diameter measurement value of the optical fiber becomes “R1 + ΔR1” when the fiber can be drawn at the drawing speed V1, the base material feed speed is
V0− (2 × R1 × ΔR1 / R0 ² ) × V1 (3)
An optical fiber manufacturing apparatus is provided.
[0011]
In a state where a base material having a diameter R0 is fed at a base material feed speed V0 and an optical fiber having a standard outer diameter R1 can be drawn at a pulling speed V1, the amount of the base material fed per second “π × (R0 / 2) ) ² × V0 ”is equal to the amount of optical fiber“ π × (R1 / 2) ² × V1 ”drawn per second, so the following equation is established.
π × (R0 / 2) ² × V0 = π × (R1 / 2) ² × V1 (4)
If transformed,
R1 ² / R0 ² = V0 / V1 (4 ′)
[0012]
Next, in a state where the base material having the diameter R0 is fed at the base material feed speed “V0 + ΔV0” and the optical fiber having the outer diameter “R1 + ΔR1” can be pulled out at the pulling speed V1, the amount of the base material fed in 1 second “ Since “π × (R0 / 2) ² × (V0 + ΔV0)” is equal to the optical fiber amount “π × {(R1 + ΔR1) / 2} ² × V1” drawn per second, the following equation is established.
π × (R0 / 2) ² × (V0 + ΔV0) = π × {(R1 + ΔR1) / 2} ² × V1 (5)
If transformed,
ΔV0 = {(R1 + ΔR1) ² / R0 ² } × V1−V0≈ (R1 ² / R0 ² + 2 × R1 × ΔR1 / R0 ² ) × V1−V0 (5 ′)
[0013]
Substituting equation (4 ′) into equation (5 ′),
ΔV0≈ (V0 / V1 + 2 × R1 × ΔR1 / R0 ² ) × V1−V0 = 2 × R1 × ΔR1 / R0 ² ) × V1 (6)
It becomes.
[0014]
When the base material feed rate is increased by ΔV0, the outer diameter of the optical fiber increases by ΔR1. To reduce the outer diameter of the optical fiber by ΔR1, it is only necessary to decrease the base material feed rate by ΔV0. Become. In other words, when the measured value of the outer diameter of the optical fiber becomes “R1 + ΔR1,” the outer diameter of the optical fiber can be returned to “R1” by setting the base material feed speed to “V0−ΔV0”. Here, since ΔV0 is given by equation (6), equation (3) is established, whereby the base material feed speed can be controlled to make the outer diameter of the optical fiber constant.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited thereby.
[0016]
FIG. 1 is an overall configuration diagram showing an optical fiber manufacturing apparatus 100 according to an embodiment of the present invention.
The optical fiber manufacturing apparatus 100 includes a heating furnace 1 that heats and softens the base material A, a base material feeding device 2 that sends the base material A to the heating furnace 1, and an optical fiber B from the base material A that is heated and softened in the heating furnace 1. A capstan G, a capstan motor Gm and a capstan motor driving unit for drawing out, an outer diameter measuring device 3 for measuring the outer diameter of the optical fiber B drawn from the heating furnace 1, and the heating furnace 1 or the heating furnace 1 A temperature sensor 4 for measuring the temperature of the base material A in the inside, and a base material feed speed control signal C (V0 + for controlling the base material feed speed based on the measured outer diameter “R1 + ΔR1” of the optical fiber B. ΔV0) is output to the base material feeding device 2 at every control timing, and the control unit 5 adjusts the control timing based on the temperature measurement value T1.
[0017]
The optical fiber B is formed with a first coating having a predetermined thickness by the coating die D1, the thermosetting furnace E1 and the outer diameter measuring device F1, and further by the coating die D2, the thermosetting furnace E2 and the outer diameter measuring device F2. 2 is formed, passed through a capstan G and a pulley H, and wound around a winding bobbin I that is rotationally driven by a winding bobbin motor Im and a winding bobbin motor driving unit K.
Note that three or more coating forming stages using a coating die, a thermosetting furnace, and an outer diameter measuring device may be provided.
[0018]
FIG. 2 is a flowchart showing the base material feed speed control processing by the optical fiber manufacturing apparatus 100.
In step S0, the controller 5 initially sets the furnace temperature to T0 (for example, 1950 ° C.), the base material feed speed to V0 (for example, 0.09 mm / min), and the optical fiber drawing speed to V1 (for example, 5 m / min). Set.
[0019]
In step S <b> 1, the control unit 5 obtains an outer diameter measurement value “R1 + ΔR1” from the outer diameter measuring device 3.
In step S2, the control unit 5 checks whether the outer diameter measurement value “R1 + ΔR1” is within the limit range (for example, 124 μm to 126 μm). If it is outside the limit range, the control unit 5 proceeds to step S3. Here, the limit range is an outer diameter range allowed as a product.
In step S3, the control part 5 alert | reports an alarm with respect to an operator.
In step S4, the control unit 5 proceeds to step S5 when instructed to stop driving by the operator, and proceeds to step S7 when instructed to continue driving by the operator. Since the operator is normally out of the limit range in the initial state of pulling out the optical fiber, the operator instructs the control unit 5 to continue the operation until the outer diameter measurement value “R1 + ΔR1” is within the limit range even if an alarm is notified. To do. The optical fiber B manufactured until the outer diameter measurement value “R1 + ΔR1” is within the limit range is discarded, and the optical fiber B manufactured after the outer diameter measurement value “R1 + ΔR1” is within the limit range is wound. Then, if an alarm is notified when the optical fiber B is being wound, an instruction to stop the operation is given.
[0020]
In step S5, the control unit 5 stops the operation. Then, the process ends.
[0021]
In step S6, the control unit 5 checks whether the outer diameter measurement value “R1 + ΔR1” is within the dead zone (for example, 124.9 μm to 125.2 μm). If it is within the dead zone, the control unit 5 returns to step S1. Here, the dead zone is a small error that can be ignored. This step S6 may be omitted.
[0022]
In step S7, the control unit 5 calculates the base material feed speed increase amount ΔV0.
ΔV0 = (2 × R1 × ΔR1 / R0 ² ) × V1 (6)
Here, R1 is a standard outer diameter (for example, 125 μm). ΔR1 is an outer diameter error from the standard outer diameter R1, and ΔR1 = measured outer diameter “R1 + ΔR1” −standard outer diameter R1. R0 is the diameter of the base material A (for example, 29.4 mm).
If the sign of the outer diameter error ΔR1 is negative, the sign of the base material feed speed increase amount ΔV0 is also negative. This means that the base material feed rate is reduced.
[0023]
In step S8, if the base material feed speed “V0 + ΔV0” is lower than the lower limit speed V0min (for example, 0.088 mm / min), the control unit 5 proceeds to step S9, and the base material feed speed “V0 + ΔV0” is set to the upper limit speed V0max (for example, 0). .092 mm / min), the process proceeds to step S10, and if the base material feed speed “V0 + ΔV0” is within the range between the lower limit speed V0min and the upper limit speed V0max, the process proceeds to step S11. Here, the lower limit speed V0min and the upper limit speed V0max are limit speeds that can suitably control the base material feed speed.
[0024]
In step S9, the control unit 5 sets the base material feed speed “V0 + ΔV0” as the lower limit speed V0min. Then, the process proceeds to step S11.
[0025]
In step S10, the control unit 5 sets the base material feed speed “V0 + ΔV0” as the upper limit speed V0max. Then, the process proceeds to step S11.
[0026]
In step S11, the control unit 5 controls the base material feed speed to “V0 + ΔV0”.
In step S <b> 12, the control unit 5 obtains a temperature measurement value T <b> 1 from the temperature sensor 43.
In step S13, the control unit 5 waits for the hold time Δt and returns to step S1.
Δt = C / {A ^{(T1-T0) / 100} } (1)
Here, C is a standard hold time (for example, 50 seconds). A is a constant (for example, 4). T0 is a standard temperature (for example, 1950 ° C.).
Δt = 50 / {4 ^{(T1-1950) / 100} } (2)
Then, when T1 = 1900 ° C., Δt = 100 seconds, when T1 = 1925 ° C., Δt = 70 seconds, when T1 = 1950 ° C., Δt = 50 seconds, when T1 = 1975 ° C., Δt = 35 seconds, and when T1 = 2000 ° C., Δt = 25 seconds. Incidentally, the viscosity (index) of the base material A is 6.5 if T1 = 1900 ° C., 6.31 if T1 = 1925 ° C., 6.12 if T1 = 1950 ° C., 5.93 if T1 = 1975 ° C., T1 = If it is 2000 degreeC, it is 5.75.
[0027]
According to the optical fiber manufacturing apparatus 100 described above, the base material feed rate “V0 + ΔV0” is controlled based on the measured outer diameter “R1 + ΔR1” of the optical fiber B, and the control timing thereof is set in the heating furnace 1 or the heating furnace 1. Adjustment is made based on the temperature measurement value T1 of the base material A. Thereby, the viscosity of the base material A varies due to the temperature variation of the base material A in the heating furnace 1, and the outer diameter of the optical fiber with respect to the change of the base material feed speed is changed. Even if the followability of changes fluctuates, the base material feed speed can be controlled by adapting the control timing to the change in followability, thus preventing the occurrence of hunting and the like, and stable optical fiber outer diameter control. Can be done.
[0028]
【The invention's effect】
According to the optical fiber manufacturing apparatus of the present invention, stable optical fiber outer diameter control can be performed even if the base material temperature fluctuates.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an optical fiber manufacturing apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a base material feed rate control process by the optical fiber manufacturing apparatus of FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Base material feeding apparatus 3 Outer diameter measuring device 4 Temperature sensor 5 Control apparatus 100 Optical fiber manufacturing apparatus A Base material B Optical fiber

Claims (6)

A heating furnace, a base material feeding means for feeding a base material to the heating furnace, an optical fiber drawing means for drawing an optical fiber from the base material softened by heating in the heating furnace, and an outer diameter of the optical fiber drawn from the heating furnace. Optical fiber outer diameter measuring means for measuring, base material feed speed control means for controlling the base material feed speed based on the measured outer diameter of the optical fiber, and measuring the temperature of the heating furnace or the base material in the heating furnace And a control timing adjusting means for adjusting a hold time , which is a waiting time until the next instruction for controlling the base material feed speed is output , based on the temperature measurement value. Optical fiber manufacturing equipment. 2. The optical fiber manufacturing apparatus according to claim 1, wherein the control timing adjusting means lengthens the hold time as the temperature measurement value is lower . 3. The optical fiber manufacturing apparatus according to claim 2, wherein the control timing adjusting means has a standard hold time of C [s], a constant of A, a temperature measurement value of T1 [° C.], and a standard temperature measurement value of T0 [° C.]. When the hold time is Δt [s],
Δt = C / {A (T1-T0) / 100}
An optical fiber manufacturing apparatus that is set by 4. The optical fiber manufacturing apparatus according to claim 3, wherein the standard hold time C = 50 [s], the constant A = 4, and the standard temperature measurement value T0 = 1950 [° C.]. 5. The optical fiber manufacturing apparatus according to claim 1, wherein the base material feed rate control means maintains the current base material feed rate when the outer diameter measurement value is within a predetermined dead zone. The base material feed speed is increased or decreased when the outer diameter measurement value is outside the dead zone and within a predetermined limit range, and a warning is issued when the outer diameter measurement value is outside the limit range. Fiber manufacturing equipment. 6. The optical fiber manufacturing apparatus according to claim 1, wherein the base material feed speed control means is configured to emit light having a standard outer diameter R <b> 1 when a base material having a diameter R <b> 0 is fed at a base material feed speed V <b> 0. If the measured value of the outer diameter of the optical fiber becomes “R1 + ΔR1” when the fiber can be drawn at the drawing speed V1, the base material feed speed is set to “V0− (2 × R1 × ΔR1 / R02) × V1”. An optical fiber manufacturing apparatus characterized by:

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