WO2022244529A1 - 光ファイバの製造方法及び光ファイバの製造装置 - Google Patents
光ファイバの製造方法及び光ファイバの製造装置 Download PDFInfo
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- WO2022244529A1 WO2022244529A1 PCT/JP2022/016599 JP2022016599W WO2022244529A1 WO 2022244529 A1 WO2022244529 A1 WO 2022244529A1 JP 2022016599 W JP2022016599 W JP 2022016599W WO 2022244529 A1 WO2022244529 A1 WO 2022244529A1
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- optical fiber
- target
- value
- tension
- quadratic function
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 211
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 43
- 238000009987 spinning Methods 0.000 claims abstract description 49
- 238000012887 quadratic function Methods 0.000 claims abstract description 48
- 230000007423 decrease Effects 0.000 claims abstract description 29
- 238000010438 heat treatment Methods 0.000 claims abstract description 11
- 230000008859 change Effects 0.000 claims description 20
- 230000036962 time dependent Effects 0.000 claims description 3
- 230000005611 electricity Effects 0.000 abstract 1
- 238000002203 pretreatment Methods 0.000 abstract 1
- 238000000034 method Methods 0.000 description 33
- 238000004364 calculation method Methods 0.000 description 25
- 230000008569 process Effects 0.000 description 25
- 239000011247 coating layer Substances 0.000 description 21
- 239000011521 glass Substances 0.000 description 11
- 229920005989 resin Polymers 0.000 description 10
- 239000011347 resin Substances 0.000 description 10
- 238000005259 measurement Methods 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 239000002019 doping agent Substances 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 230000002093 peripheral effect Effects 0.000 description 3
- 238000004904 shortening Methods 0.000 description 3
- 230000004308 accommodation Effects 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 238000010801 machine learning Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000002123 temporal effect Effects 0.000 description 2
- 229920001187 thermosetting polymer Polymers 0.000 description 2
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
- C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
- C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
- C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
- C03B37/0253—Controlling or regulating
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2205/00—Fibre drawing or extruding details
- C03B2205/40—Monitoring or regulating the draw tension or draw rate
Definitions
- the present invention relates to an optical fiber manufacturing method and an optical fiber manufacturing apparatus.
- An optical fiber is manufactured by heating an optical fiber preform in a spinning furnace and drawing it into an optical fiber.
- it is known to adjust the power supplied to the spinning furnace according to the speed at which the optical fibers are taken, the tension applied to the optical fibers, and the like.
- Patent Document 1 describes a technique for preventing the power supplied to a spinning furnace from being unnecessarily adjusted in response to temporary fluctuations in the tension applied to the optical fiber due to temporary fluctuations in the speed with which the optical fiber is pulled. , adjusting the power supplied to the spinning furnace so that the ratio of the tension applied to the optical fiber divided by the speed at which the optical fiber is pulled is maintained at a target value.
- Patent Document 1 does not consider a pretreatment process from when the spinning furnace starts heating the optical fiber preform until the above ratio reaches the target value. For example, even if the ratio is adjusted to the target value by adjusting the power supplied to the spinning furnace, the ratio may deviate from the target value and the power must be adjusted again. Therefore, there is a demand for improving the productivity of optical fibers by shortening the time required for the pretreatment process.
- an object of the present invention is to provide an optical fiber manufacturing method and an optical fiber manufacturing apparatus capable of improving the productivity of optical fibers.
- the method for manufacturing an optical fiber of the present invention provides a method of heating an optical fiber preform in a spinning furnace to adjust the tension applied to the optical fiber and the speed at which the optical fiber is drawn when the optical fiber is drawn.
- T and V respectively, the target value of the tension is Ttarget , and the target value of the velocity is Vtarget . It is characterized by comprising a pretreatment step of supplying electric power to the spinning furnace so as to decrease along the function to become the T target /V target .
- an optical fiber manufacturing apparatus of the present invention includes a spinning furnace for heating an optical fiber preform to draw an optical fiber, a power supply section for supplying power to the spinning furnace, a control unit, wherein the control unit sets the tension applied to the optical fiber when the optical fiber is drawn and the speed at which the optical fiber is taken over to T and V, respectively, and sets the target value of the tension to T target ;
- the target value of the velocity is V target
- T/V decreases with time along a quadratic function whose vertex value is T target /V target to reach T target /V target .
- the power supply unit is controlled.
- Ttarget/ Vtarget is a value corresponding to the target diameter of the optical fiber, and this Ttarget / Vtarget is determined according to, for example, the material of the optical fiber preform and the spinning furnace.
- T/V decreases along the above-described quadratic function to T target /V target , so that when T / V decreases linearly
- T/V decreases linearly
- T/V it has been found that, after T/V reaches Ttarget / Vtarget , it becomes difficult to deviate from the Ttarget / Vtarget as compared with the case where the rate of decrease of T/V is approximately constant. Therefore, after T/V becomes Ttarget / Vtarget , adjustment of the electric power supplied to the spinning furnace is suppressed.
- the time required for T/V to stabilize at the target value that is, the time required for the tension T and the velocity V to stabilize at the target value
- the productivity of the optical fiber can be improved.
- the quadratic function representing the time-dependent change T(t)/V(t) of the T/V is defined by the time t 0 when the T/V becomes the T target /V target and the optical fiber matrix
- T (t) / V (t) a 0 (tt 0 ) 2 + (T target /V target )
- a 0 is a constant predetermined according to the material It may be represented by
- the present inventor has diligently studied changes in T/V over time during the period from the start of heating the optical fiber preform until the T/V becomes substantially constant. As a result, the present inventor found that when a constant power is supplied to the spinning furnace, until a certain point, T/V decreases with the passage of time along a quadratic function in which the value at the peak is the minimum value, and this The peak of the quadratic function is reached, and from that point on, T/V becomes approximately constant at the value at this peak, and this approximately constant T/V value responds to the constant power value. .
- the constant a 0 and the time t 0 can be obtained in advance for a given optical fiber preform by experiment, and the constant a 0 and the time t 0 can be obtained so that T/V decreases in accordance with the above formula. can also be known in advance.
- T/V can be caused to decrease over time approximately along a quadratic function with a peak value of T target /V target and control load can be reduced.
- a constant power is supplied to the spinning furnace for a predetermined period to obtain a quadratic function representing the change over time of the T/V.
- the constant power supplied to the spinning furnace may be changed based on the difference between the T/V value at the vertex of the quadratic function and the Ttarget / Vtarget .
- T/V decreases with time along a quadratic function in which the value at the peak is the minimum value until a certain point.
- T/V changes over time and the vertex value becomes T target /V target . It can be reduced along a quadratic function that is V target so that T target /V target .
- the pretreatment step is performed after the positioning step of inserting the neck-down portion of the optical fiber preform to the position of the heater in the spinning furnace.
- the tension is preferably tension applied to the bare optical fiber.
- the value of tension T does not include the tension component caused by the coating layer. Therefore, T/V can be calculated more accurately than when the value of the tension T includes a tension component due to the coating layer.
- the tension applied to the bare optical fiber is Tg
- the cross-sectional area of the bare optical fiber is Sg
- the target value of the cross-sectional area of the bare optical fiber is Starget
- the tension Tg applied to the bare optical fiber is actually affected by the variation of the cross-sectional area Sg of the bare optical fiber. Therefore, as in the above equation, by adding the ratio of the cross-sectional area of the bare optical fiber to the target value of the cross-sectional area of the bare optical fiber to the tension Tg, the value of T/V can be obtained more accurately. can be calculated to
- an optical fiber manufacturing method and optical fiber manufacturing apparatus capable of improving the productivity of optical fibers can be provided.
- FIG. 2 is a diagram schematically showing a cross section perpendicular to the longitudinal direction of an optical fiber preform for manufacturing the optical fiber shown in FIG. 1; 1 is a diagram schematically showing an optical fiber manufacturing apparatus according to an embodiment of the present invention; FIG. 4 is a flow chart showing steps of an optical fiber manufacturing method according to an embodiment of the present invention. 4 is a graph showing changes in T/V over time according to an embodiment of the present invention; It is a graph which shows roughly the time-dependent change of T/V based on the modification of this invention.
- FIG. 1 is a diagram schematically showing a cross section perpendicular to the longitudinal direction of an optical fiber according to an embodiment of the present invention.
- the optical fiber 1 of this embodiment mainly includes a core 10, a clad 11 surrounding the outer peripheral surface of the core 10, and a coating layer 12 covering the outer peripheral surface of the clad 11.
- the outer shape of the core 10 in the cross section is circular, and the core 10 is arranged at the center of the clad 11 .
- the outer shape of the clad 11 in the cross section may be non-circular such as elliptical or polygonal.
- FIG. 1 shows an optical fiber 1 in which the outer shape of the cladding 11 is circular.
- the refractive index of the core 10 is made higher than that of the clad 11 .
- the core 10 is made of silica glass without any additives
- the clad 11 is made of silica glass doped with a dopant such as fluorine (F) that lowers the refractive index.
- the core 10 may be made of silica glass doped with a dopant such as germanium (Ge) that increases the refractive index
- the clad 11 may be made of silica glass without any additives.
- the core 10 may be made of silica glass doped with a dopant that increases the refractive index
- the clad 11 may be made of silica glass doped with a dopant that lowers the refractive index.
- the dopant for increasing the refractive index and the dopant for decreasing the refractive index are not particularly limited.
- the coating layer 12 is made of resin.
- the resin forming the coating layer 12 include thermosetting resins and ultraviolet curable resins.
- the coating layer 12 may have a single-layer structure consisting of one resin layer surrounding the clad 11, or may have a multi-layer structure consisting of a plurality of resin layers.
- FIG. 2 is a diagram schematically showing a cross section perpendicular to the longitudinal direction of the optical fiber preform for manufacturing the optical fiber 1 shown in FIG.
- the optical fiber preform 1P is composed of a rod-shaped core glass body 10P that serves as the core 10, and a clad glass body 11P that surrounds the outer peripheral surface of the core glass body 10P and serves as the clad 11.
- the outer shape of the clad glass body 11P in the cross section is circular, and the core glass body 10P is arranged at the center of the clad glass body 11P.
- the outer shape of the core glass body 10P in the cross section is circular.
- FIG. 3 is a diagram schematically showing an optical fiber manufacturing apparatus according to this embodiment.
- the optical fiber manufacturing apparatus 100 includes a spinning furnace 110, a sending section 115, a first outer diameter measuring section 121, a cooling device 130, a coating section 140, a curing section 145, a 2 Outer diameter measurement unit 122, turn pulley 150, tension meter 151, take-up device 160, speedometer 161, winding device 170, calculation unit 180, memory 190, power supply unit 200, control unit and CO as main components.
- the control unit CO consists of integrated circuits such as microcontrollers, ICs (Integrated Circuits), LSIs (Large-scale Integrated Circuits), ASICs (Application Specific Integrated Circuits), and NC (Numerical Control) devices. Further, when the NC device is used, the controller CO may use a machine learning device or may not use a machine learning device. As described below, several configurations of the optical fiber manufacturing apparatus 100 are controlled by the controller CO.
- the spinning furnace 110 includes a core tube 111 and a heater 112 arranged to surround the core tube 111 so as to heat the core tube 111 .
- the heater 112 generates heat according to power supplied from the power supply unit 200 .
- the power supply unit 200 adjusts the power supplied to the heater 112 according to the control signal from the control unit CO.
- the feed-out part 115 is attached to the upper end of the optical fiber preform 1P, and is configured to feed the optical fiber preform 1P into the accommodation space of the core tube 111 from the lower end side.
- the delivery unit 115 adjusts the delivery speed of the optical fiber preform 1P according to the control signal from the control unit CO.
- the furnace core tube 111 is heated by the heater 112 generating heat.
- the lower end of the optical fiber preform 1P is heated by inserting the optical fiber preform 1P into the housing space of the core tube 111 from the lower end side.
- the lower end portion of the optical fiber preform 1P heated by the heater 112 is melted, and as a result, a downwardly tapering neckdown portion ND is formed at the lower end portion of the optical fiber preform 1P.
- a glass wire is pulled out from the neck-down portion ND. When this drawn glass wire comes out from the lower opening of the furnace core tube 111, it immediately solidifies, the core glass body 10P becomes the core 10, the clad glass body 11P becomes the clad 11, and the core 10 and the clad 11 are formed.
- An optical fiber bare wire 1N composed of
- the first outer diameter measurement unit 121 is arranged below the spinning furnace 110, measures the outer diameter of the bare optical fiber 1N drawn in the spinning furnace 110, and measures the diameter of the bare optical fiber 1N. to the calculation unit 180.
- the first outer diameter measurement unit 121 for example, it has a light irradiation unit that emits laser light and a light receiving unit that receives the laser light emitted from the light irradiation unit. A configuration in which they are arranged so as to sandwich the line 1N can be mentioned.
- the cooling device 130 is arranged below the first outer diameter measuring section 121 and cools the bare optical fiber 1N to an appropriate temperature.
- the application section 140 is arranged below the cooling device 130 , and the curing section 145 is arranged below the application section 140 .
- An uncured resin that forms the coating layer 12 is applied to the bare optical fiber 1 ⁇ /b>N by the coating unit 140 , and the resin is cured by the curing unit 145 to form the coating layer 12 .
- the bare optical fiber 1N becomes the optical fiber 1.
- FIG. When the coating layer 12 is made of a thermosetting resin, the curing unit 145 is configured to apply heat to the resin. be.
- the second outer diameter measuring section 122 is arranged below the curing section 145 and measures the outer diameter of the coating layer 12 which is the outer diameter of the optical fiber 1 .
- the second outer diameter measurement unit 122 outputs a signal indicating the measured value of the outer diameter of the optical fiber 1 to the calculation unit 180 and the control unit CO.
- the second outer diameter measuring section 122 for example, a configuration similar to that of the first outer diameter measuring section 121 can be given.
- the turn pulley 150 is arranged below the second outer diameter measuring section 122 .
- the direction of the optical fiber 1 is changed by the turn pulley 150, and the take-up device 160 rotates to take it. Thereby, tension is applied to the optical fiber 1 .
- the take-up device 160 adjusts the speed at which the optical fiber 1 is taken in accordance with a control signal from the controller CO. Since the optical fiber 1 is obtained by coating the bare optical fiber 1N with the coating layer 12, it can be understood that this speed is also the speed at which the bare optical fiber 1N is taken.
- the optical fiber 1 that has passed through a take-up device 160 that takes up the optical fiber 1 is sent to a take-up device 170 and taken up by the take-up device 170 .
- the tension meter 151 is provided on the turn pulley 150, measures the tension, and outputs a signal indicating the value of the tension to the calculation unit 180.
- a configuration using a strain gauge can be mentioned.
- the speedometer 161 is provided in the take-up device 160, measures the take-up speed of the optical fiber 1 based on the number of revolutions per unit time of the take-up device 160, and transmits a signal indicating the value of the speed to the calculation unit 180 and the controller. Output to section CO.
- the speedometer 161 for example, a configuration using a magnetic sensor can be given.
- the memory 190 is connected to the calculation unit 180 and the control unit CO.
- the memory 190 is configured to store information and read out the stored information.
- the memory 190 is, for example, a non-transitory recording medium, and is preferably a semiconductor recording medium such as RAM (Random Access Memory) or ROM (Read Only Memory). Any form of recording medium, such as a recording medium, may be included. Note that "non-transitory” recording media include recording media that can read all data except transitory, propagating signals, and do not exclude volatile recording media. do not have.
- the memory 190 stores information necessary for calculation by the calculation unit 180 to be described later, information necessary for control of each configuration by the control unit CO, and the like.
- the calculation unit 180 performs various calculations based on input information.
- the calculation unit 180 may have, for example, the same configuration as the control unit CO.
- the calculation unit 180 calculates the , the cross-sectional area Sg of the bare optical fiber 1N is calculated by the following equation (1).
- Sg ⁇ (Dn/2) 2 (1)
- the calculation unit 180 receives the signal input from the first outer diameter measurement unit 121 and the input from the second outer diameter measurement unit 122.
- the tension measured by the tension meter 151 is the tension applied to the optical fiber 1
- this tension is the sum of the tension applied to the bare optical fiber 1N and the tension applied to the coating layer 12.
- the tension Tc can be calculated by the following equation (3).
- Tc ⁇ V ⁇ Sc (3)
- ⁇ is the tension per unit area of the coating layer 12
- ⁇ is the proportionality constant, and these values are stored in the memory 190 .
- the calculation unit 180 of the present embodiment calculates the tension Tg by the following equation (4).
- Tg Tf- ⁇ V ⁇ Sc (4)
- the tension Tg applied to the bare optical fiber 1N is actually affected by the variation of the cross-sectional area Sg of the bare optical fiber 1N.
- T represented by the above equation (5) is obtained by adding the ratio between the cross-sectional area of the bare optical fiber 1N and the target value S target of the cross-sectional area of the bare optical fiber 1N to the tension Tg, This is the tension applied to the bare optical fiber 1N considering the influence of the variation of the cross-sectional area Sg of the bare optical fiber 1N.
- the calculation unit 180 outputs a signal indicating the value of T as the tension applied to the optical fiber 1 to the control unit CO.
- the calculation unit 180 also outputs a signal indicating the value of the speed at which the optical fiber 1 is received from the speedometer 161 to the control unit CO.
- FIG. 4 is a flow chart showing the steps of the method for manufacturing the optical fiber 1 according to this embodiment. As shown in FIG. 4, this manufacturing method includes a positioning process P1, a pretreatment process P2, and a drawing process P3.
- the control unit CO controls the power supply unit 200 to supply power from the power supply unit 200 to the heater 112 to heat the furnace core tube 111 .
- the power supplied from the power supply unit 200 to the heater 112 is constant power.
- the control unit CO controls the delivery unit 115 to deliver the optical fiber preform 1P from the lower end side of the core. It is fed into the housing space of the tube 111 .
- the lower end portion of the optical fiber preform 1P is melted, and as a result, a downwardly tapering neckdown portion ND is formed at the lower end portion of the optical fiber preform 1P.
- the neck-down portion ND is lowered to the position of the heater 112 by feeding the optical fiber preform 1P by the feeding section 115 .
- the position of the heater 112 is a position along the central axis of the furnace core tube 111 that overlaps the section from the upper end to the lower end of the heater 112 .
- the optical fiber preform 1P is fed into the accommodation space until the upper end of the neckdown portion ND reaches a specific position above the center of the heater 112 and below the upper end of the heater 112 by a predetermined distance.
- the optical fiber preform 1P is positioned.
- the optical fiber 1 is drawn from the neckdown portion ND of the optical fiber preform 1P even when the optical fiber preform 1P is lowered.
- the control unit CO controls the take-up device 160 based on the value of the outer diameter of the optical fiber 1 measured by the second outer diameter measuring unit 122 so that the outer diameter of the optical fiber 1 becomes the target value. Adjust the speed at which 1 is taken. However, since the molten portion of the optical fiber preform 1P is heated during this step, the outer diameter of the drawn optical fiber 1 is not stable. After positioning the optical fiber preform 1P, power may be supplied from the power supply unit 200 to the heater 112, and the power supplied to the heater 112 may not be constant.
- control unit CO controls the take-up device 160 based on the value of the outer diameter of the bare optical fiber 1N measured by the first outer diameter measuring unit 121 so that the outer diameter of the bare optical fiber 1N becomes the target value. may be controlled to adjust the speed at which the optical fiber 1 is taken.
- the tension applied to the optical fiber 1 to be drawn and the speed at which the optical fiber 1 is taken have values such that the outer diameter of the optical fiber 1 to be drawn is stable.
- a value is determined according to, for example, the material of the optical fiber preform 1P, the spinning furnace, and the like, and can be obtained through experiments or the like.
- Such values for each of the above tensions and velocities are stored in memory 190 as target values.
- the control unit CO controls the light input from the second outer diameter measuring unit 122 so that the speed increases to reach the target value and the outer diameter of the optical fiber 1 reaches a predetermined value.
- the take-up device 160 is controlled based on the value of the outer diameter of the fiber 1 and the value of the take-up speed of the optical fiber 1 measured by the speedometer 161 .
- the control unit CO controls the take-up device 160 based on the value of the outer diameter of the bare optical fiber 1N measured by the first outer diameter measurement unit 121 and the value of the take-up speed of the optical fiber 1 measured by the speedometer 161. may be controlled.
- the control unit CO also controls the power supply unit 200 based on the value of the tension T applied to the optical fiber 1 calculated by the calculation unit 180 and the value of the speed measured by the speedometer 161 .
- the target tension value is Ttarget
- the target speed value is Vtarget
- T/V changes to the peak with the lapse of time. is decreased along a quadratic function of Ttarget / Vtarget to Ttarget / Vtarget
- the power supply unit 200 is controlled, and the heating temperature of the optical fiber preform 1P is adjusted.
- the above quadratic function representing the change in T/V over time T(t)/V(t) is defined by the time t 0 at which T/V becomes T target /V target and the optical fiber
- a 0 is a constant that is predetermined according to the base material 1P for the machine, it is represented by the following formula (6).
- T(t)/V(t) a0 ( tt0 ) 2+ ( Ttarget / Vtarget ) (6)
- the present inventors diligently studied changes in T/V over time during the period from the start of heating the optical fiber preform 1P until the T/V becomes substantially constant.
- the present inventor found that when a constant power is supplied to the spinning furnace 110, until a certain point in time, T/V decreases over time along a quadratic function in which the value at the peak is the minimum value, It was found that the apex of this quadratic function is reached, and from that point on, T/V becomes substantially constant at the value at this apex, and this substantially constant value corresponds to the constant power value. For this reason, the constant a 0 and the time t 0 can be determined in advance for the optical fiber preform 1P by experiments or the like, and a constant value such that T/V decreases according to the equation (6). Power can also be known in advance. In this embodiment, these values obtained by experiments are stored in the memory 190 in advance.
- the constant power supplied to the heater 112 in the positioning process P1 is such constant power that T/V decreases according to equation (6). Therefore, the power supplied to the heater 112 at the beginning of the pretreatment process P2 is the constant power. As a result, T/V decreases over time along a quadratic function whose vertex value is T target /V target , thereby reducing the control load on the control unit CO.
- FIG. 5 is a graph showing temporal changes in T/V in this embodiment.
- the portion indicated by the thin line is the temporal change of T/V during the positioning process P1.
- the portion indicated by the thick line is the change over time of T/V during the period of the pretreatment process P2.
- the above formula (6) is indicated by a dashed line.
- T/V decreases with time along a quadratic function whose vertex value is Ttarget / Vtarget to Ttarget / Vtarget , The velocity V becomes V target and the tension T becomes T target .
- the outer diameter of the bare optical fiber 1N is stabilized and the outer diameter of the optical fiber 1 is stabilized.
- This step is a step of drawing the optical fiber 1 after the pretreatment step P2, that is, in a state in which the outer diameter of the optical fiber 1 is stabilized.
- the control unit CO controls the delivery unit 115 so that the position of the neckdown portion ND of the optical fiber preform 1P with respect to the heater 112 does not change, and adjusts the delivery amount of the optical fiber preform 1P. be done. Further, the control unit CO controls the take-up device 160 based on the value of the speed V measured by the speedometer 161 so that the speed V is maintained at V target .
- control unit CO controls the power supply unit 200 so that T/V is maintained at Ttarget / Vtarget , and the heating temperature of the optical fiber preform 1P is adjusted. Therefore, the optical fiber 1 whose outer diameter reaches the target value can be stably drawn.
- the method for manufacturing an optical fiber includes the pretreatment step P2.
- the tension applied to the optical fiber 1 when the optical fiber preform 1P is heated in the spinning furnace 110 and the optical fiber 1 is drawn, and the speed at which the optical fiber 1 is pulled are set to T and V, respectively.
- T/V decreases with time along a quadratic function whose peak value is Ttarget / Vtarget to Ttarget / Power is supplied to the spinning furnace 110 so that V target is reached.
- the optical fiber manufacturing apparatus 100 in the present embodiment includes a spinning furnace 110 for heating the optical fiber preform 1P to draw the optical fiber 1, a power supply unit 200 for supplying power to the spinning furnace 110, and a controller. and a part CO.
- the control unit CO controls the power supply unit 200 so that T/V decreases along a quadratic function whose peak value is Ttarget / Vtarget over time to Ttarget / Vtarget . .
- T/V decreases along the above-described quadratic function to T target /V target , so that when T / V decreases linearly
- T/V decreases along the above-described quadratic function to T target /V target , so that when T / V decreases linearly
- the time required for T/V to stabilize at the target value that is, the time until the tension T and the velocity V stabilize at the target value
- the productivity of the optical fiber 1 can be improved by shortening the time required for the process.
- the tension T is the tension applied to the bare optical fiber 1N, which is Tg, the cross-sectional area of the bare optical fiber 1N, Sg, and the light
- the target value of the cross-sectional area of the bare fiber 1N is Starget , and is calculated by the above equation (5). Therefore, the tension T in this embodiment is the tension applied to the bare optical fiber 1N, and the tension component caused by the coating layer 12 is not included in the value of the tension T. Therefore, the value of T/V can be calculated more accurately than when the value of the tension T includes a component of tension caused by the coating layer 12 .
- the tension Tg applied to the bare optical fiber 1N is actually affected by fluctuations in the cross-sectional area Sg of the bare optical fiber 1N. Therefore, as in the present embodiment, by adding the ratio between the measured value of the cross-sectional area of the bare optical fiber 1N and the target value of the cross-sectional area of the bare optical fiber 1N to the tension Tg by the equation (5), The value of T/V can be calculated more accurately.
- the change in T/V over time in the positioning step P1 which is the period until the tip of the optical fiber preform 1P reaches the position of the heater 112, tends to deviate from the quadratic function. It turns out that there is For this reason, until the neckdown portion ND of the optical fiber preform 1P reaches the position of the heater 112, it is difficult to decrease T/V along a quadratic function, and a control load may be applied.
- the pretreatment process P2 since the pretreatment process P2 is performed after the positioning process P1, such a control load can be reduced. However, the pretreatment process P2 may be performed during the positioning process P1.
- the pretreatment process P2 in which electric power is supplied to the spinning furnace 110 so that T/V is reduced according to the above equation (6) has been described as an example.
- the spinning furnace 110 is adjusted so that T/V decreases with time along a quadratic function whose peak value is Ttarget / Vtarget to Ttarget / Vtarget . Power should be supplied.
- a constant power EP1 is supplied to the spinning furnace 110.
- the constant power EP1 is the same as the constant power supplied in the positioning process P1, but may be different. Since the power supplied to the spinning furnace 110 is constant, T/V decreases along a quadratic function during the period in which the constant power EP1 is supplied.
- FIG. 6 is a graph schematically showing the change in T/V over time in this modified example, and the change in T/V over time is indicated by a solid line.
- the calculation unit 180 approximates a quadratic function representing a change in T/V over time based on a plurality of T/V values during the period in which the constant power EP1 is supplied. In FIG.
- the calculated quadratic function is indicated by a dashed line. Note that the quadratic function is shown slightly shifted from the change in T/V over time.
- An approximation method includes, for example, the least squares method.
- the calculation unit 180 calculates the difference d between the value of T/V at the vertex of the quadratic function and Ttarget / Vtarget , and outputs a signal indicating the difference d to the control unit CO.
- the difference d is the value of T/V minus Ttarget / Vtarget , and has positive and negative values.
- the control unit CO controls the power supply unit 200 based on this difference d. Specifically, when the difference d is positive and the absolute value of the difference d is greater than a predetermined value, the controller CO controls that the electric power supplied to the spinning furnace 110 is higher than the constant electric power EP1 from time t1.
- the power supply unit 200 is controlled so as to supply power. For this reason, the viscosity of the molten optical fiber preform 1P decreases, the tension T decreases, and the T/V decreases.
- the controller CO controls that the power supplied to the spinning furnace 110 becomes constant power lower than the constant power EP1 from time t1.
- the power supply unit 200 is controlled as follows.
- the control unit CO controls the power supply unit 200 so that the power supplied to the spinning furnace 110 is maintained at the constant power EP1 even after the time t1. to control.
- FIG. 6 shows a case where the power supplied to the spinning furnace 110 becomes constant power EP2 higher than constant power EP1 from time t1.
- the calculation unit 180 calculates, by approximation, a quadratic function representing the change in T/V over time based on a plurality of T/V values after time t1.
- the calculated quadratic function is indicated by a chain double-dashed line. Note that the quadratic function is shown slightly shifted from the change in T/V over time.
- the calculation unit 180 calculates the difference d between the value of T/V at the vertex of the quadratic function and Ttarget / Vtarget , and outputs a signal indicating the difference d to the control unit CO.
- the control unit CO controls the power supply unit 200 based on the difference d in the same manner as when the calculation unit 180 calculated the difference d between the value of T/V and T target /V target before time t1. .
- FIG. 6 shows a case where a constant electric power EP3 higher than the constant electric power EP2 is supplied to the spinning furnace 110 from time t2 when a predetermined period has elapsed from time t1.
- a dashed line indicates a quadratic function calculated based on a plurality of T/V values during the period in which the constant power EP3 is supplied.
- the absolute value of the difference between the value of T/V at the vertex of this quadratic function and Ttarget / Vtarget is less than the predetermined value, and the value of T/V at time t3 is T target /V target .
- the tension T is calculated by the formula (5)
- the tension T may be a value calculated by the above formula (4).
- the tension T is the tension applied to the bare optical fiber 1N, and the value of the tension T does not include the tension component caused by the coating layer 12.
- FIG. Therefore, the value of T/V in the bare optical fiber 1N can be calculated more accurately than when the value of the tension T includes a component of tension caused by the coating layer 12 .
- the control load can be reduced.
- the tension T may be the value measured by the tension meter 151 . In this case, the control load can be reduced because there is no need to calculate equations (4) and (5).
- an optical fiber manufacturing method and an optical fiber manufacturing apparatus capable of improving the productivity of optical fibers are provided, and can be used in various fields related to optical fibers.
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Abstract
Description
T(t)/V(t)=a0(t-t0)2+(Ttarget/Vtarget)
で表されることとしてもよい。
T=Tg×(Starget/Sg)
により算出される値とされることがより好ましい。
Sg=π(Dn/2)2 ・・・(1)
また、演算部180は、光ファイバ1の径をDcとし、被覆層12の断面積をScとする場合に、第1外径測定部121から入力する信号及び第2外径測定部122から入力する信号に基づいて、被覆層12の断面積Scを以下の式(2)により算出する。
Sc=π{(Dc/2)-(Dn/2)}2 ・・・(2)
Tc=α・β・V・Sc ・・・(3)
なお、αは被覆層12の単位面積当たりの張力、βは比例定数であり、これらの値はメモリ190に記憶されている。本実施形態の演算部180は、張力計151によって測定される張力をTfとし、光ファイバ裸線1Nに加えられる張力をTgとする場合に、当該張力Tgを下記式(4)により算出する。
Tg=Tf-α・β・V・Sc ・・・(4)
T=Tg×(Starget/Sg) ・・・(5)
なお、Stargetは光ファイバ裸線1Nの目標となる断面積であり、この値はメモリ190に記憶されている。ここで、光ファイバ裸線1Nに加えられる張力Tgは、実際には、光ファイバ裸線1Nの断面積Sgの変動の影響を受ける。したがって、上記の式(5)で表されるTは、光ファイバ裸線1Nの断面積と光ファイバ裸線1Nの断面積の目標値Stargetとの比を張力Tgに加味したものであり、光ファイバ裸線1Nの断面積Sgの変動の影響が考慮された光ファイバ裸線1Nに加えられる張力である。
まず、本工程を行う準備段階として、図2に示される光ファイバ用母材1Pを購入等によって準備し、光ファイバの製造装置100の送り出し部115に固定する。また、制御部COは、電力供給部200を制御して当該電力供給部200からヒータ112に電力を供給させ、炉心管111を加熱する。本実施形態では、電力供給部200からヒータ112に供給される電力は一定の電力とされる。そして、炉心管111が加熱されている状態において、制御部COは送り出し部115を制御し、当該送り出し部115に光ファイバ用母材1Pを送り出させ、光ファイバ用母材1Pを下端側から炉心管111の収容空間に送り込む。光ファイバ用母材1Pの下端部は溶融状態となり、その結果、光ファイバ用母材1Pの下端部に、下方に向かって先細りになるネックダウン部NDが形成される。送り出し部115によって光ファイバ用母材1Pを送り出させることで、このネックダウン部NDをヒータ112の位置まで降下させる。なお、ヒータ112の位置とは、炉心管111の中心軸線に沿った位置のうちヒータ112の上端部から下端部までの区間と重なる位置である。本実施形態では、ネックダウン部NDの上端の位置が、ヒータ112の中心より上方かつヒータ112の上端より所定距離だけ下方の特定位置となるまで、光ファイバ用母材1Pを収容空間に送り込む。こうして、光ファイバ用母材1Pが位置決めされる。
次に、本工程を行う。一般的に、線引きされる光ファイバ1に加わる張力及び当該光ファイバ1を引き取る速度には、線引きされる光ファイバ1の外径が安定するような値がある。このような値は、例えば、光ファイバ用母材1Pの材質や紡糸炉等に応じて定められ、実験等によって求めることができる。上記の張力及び速度のそれぞれにおけるこのような値は、目標値として、メモリ190に記憶されている。本工程では、制御部COは、上記速度が増加して目標値となるように、かつ、光ファイバ1の外径が所定値となるように、第2外径測定部122から入力される光ファイバ1の外径の値及び速度計161で測定される光ファイバ1を引き取る速度の値に基づいて、引取装置160を制御する。なお、制御部COは、第1外径測定部121で測定される光ファイバ裸線1Nの外径の値及び速度計161で測定される光ファイバ1を引き取る速度の値に基づいて引取装置160を制御してもよい。また、制御部COは、演算部180で算出される光ファイバ1に加わる張力Tの値及び速度計161で測定される速度の値に基づいて、電力供給部200を制御する。具体的には、制御部COは、光ファイバ1を引き取る速度をVとし、張力の目標値をTtargetとし、速度の目標値をVtargetとする場合に、T/Vが時間の経過とともに頂点の値がTtarget/Vtargetである2次関数に沿って減少してTtarget/Vtargetとなるように、電力供給部200を制御し、光ファイバ用母材1Pの加熱温度が調節される。
T(t)/V(t)=a0(t-t0)2+(Ttarget/Vtarget) ・・・(6)
ここで、本発明者は、光ファイバ用母材1Pを加熱し始めてから、上記T/Vが概ね一定になるまでの期間におけるT/Vの経時的変化について鋭意研究した。その結果、本発明者は、紡糸炉110に一定電力を供給する場合、ある時点まではT/Vが時間の経過とともに頂点における値が最小値となる2次関数に沿うように減少して、この2次関数の頂点に到達し、当該ある時点からはT/Vがこの頂点での値で概ね一定になり、この概ね一定となる値が一定電力の値に応じることを見出した。このため、光ファイバ用母材1Pに対して、上記の定数a0、及び時間t0を予め実験等により求めることができ、T/Vが式(6)に沿って減少するような一定の電力も予め把握し得る。本実施形態では、予め実験により求められたこれら値がメモリ190に記憶されている。また、本実施形態では、上記の位置決め工程P1においてヒータ112に供給される一定の電力は、T/Vが式(6)に沿って減少するような一定の電力とされる。このため、前処理工程P2の初期にヒータ112に供給される電力は、当該一定の電力となる。このため、T/Vが時間の経過とともに頂点の値がTtarget/Vtargetである2次関数に概ね沿って減少するようになるため、制御部COの制御負荷を低減できる。
本工程は、前処理工程P2の後、つまり、光ファイバ1の外径が安定した状態で光ファイバ1を線引きする工程である。本実施形態では、制御部COは、光ファイバ用母材1Pのネックダウン部NDのヒータ112に対する位置が変化しないように、送り出し部115を制御し、光ファイバ用母材1Pの送り出し量が調節される。また、制御部COは、速度計161で測定される速度Vの値に基づいて当該速度VがVtargetに維持されるように引取装置160を制御する。また、制御部COは、T/VがTtarget/Vtargetに維持されるように、電力供給部200を制御し、光ファイバ用母材1Pの加熱温度が調節される。このため、外径が目標値となった光ファイバ1を安定して線引きできる。
Claims (7)
- 光ファイバ用母材を紡糸炉により加熱して光ファイバを線引きする際に前記光ファイバに加わる張力及び前記光ファイバを引き取る速度をそれぞれT、Vとし、前記張力の目標値をTtargetとし、前記速度の目標値をVtargetとする場合に、T/Vが時間の経過とともに頂点における値がTtarget/Vtargetである2次関数に沿って減少して前記Ttarget/Vtargetになるように、前記紡糸炉に電力を供給する前処理工程を備える
ことを特徴とする光ファイバの製造方法。 - 前記T/Vの経時的変化T(t)/V(t)を表す前記2次関数は、前記T/Vが前記Ttarget/Vtargetになる時間をt0、前記光ファイバ用母材に応じて予め定まる定数をa0とする場合に、下記式
T(t)/V(t)=a0(t-t0)2+(Ttarget/Vtarget)
で表される
ことを特徴とする請求項1に記載の光ファイバの製造方法。 - 前記前処理工程において、所定の期間にわたって一定電力を前記紡糸炉に供給することにより、前記T/Vの経時的変化を表す2次関数を求め、当該2次関数の頂点における前記T/Vの値と前記Ttarget/Vtargetとの差に基づいて前記紡糸炉に供給する前記一定電力を変更する
ことを特徴とする請求項1に記載の光ファイバの製造方法。 - 前記光ファイバ用母材のネックダウン部を前記紡糸炉におけるヒータの位置まで挿入する位置決め工程の後に、前記前処理工程を行う
ことを特徴とする請求項1から3のいずれか1項に記載の光ファイバの製造方法。 - 前記張力は、光ファイバ裸線に加えられる張力である
ことを特徴とする請求項1から4のいずれか1項に記載の光ファイバの製造方法。 - 前記張力が、前記光ファイバ裸線に加えられる張力をTg、前記光ファイバ裸線の断面積をSg、及び前記光ファイバ裸線の断面積の目標値をStargetとする場合に、下記式
T=Tg×(Starget/Sg)
により算出される値とされる
ことを特徴とする請求項5項に記載の光ファイバの製造方法。 - 光ファイバ用母材を加熱して光ファイバを線引きする紡糸炉と、
前記紡糸炉に電力を供給する電力供給部と、
制御部と、
を備え、
前記制御部は、前記光ファイバを線引きする際に前記光ファイバに加わる張力及び前記光ファイバを引き取る速度をそれぞれT、Vとし、前記張力の目標値をTtargetとし、前記速度の目標値をVtargetとする場合に、T/Vが時間の経過とともに頂点における値がTtarget/Vtargetである2次関数に沿って減少して前記Ttarget/Vtargetとなるように、前記電力供給部を制御する
ことを特徴とする光ファイバの製造装置。
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JPH05139771A (ja) | 1991-11-22 | 1993-06-08 | Fujikura Ltd | 光フアイバ線引炉の制御方法 |
JPH11255534A (ja) * | 1998-03-10 | 1999-09-21 | Furukawa Electric Co Ltd:The | 光ファイバの線引き方法 |
WO2008062465A2 (en) * | 2006-10-17 | 2008-05-29 | Sterlite Optical Technologies Ltd. | Apparatus & method for drawing optical fiber having desired waveguide parameters and fiber produced thereby |
JP2009126755A (ja) * | 2007-11-26 | 2009-06-11 | Sumitomo Electric Ind Ltd | 光ファイバの線引き方法 |
JP2010269971A (ja) * | 2009-05-21 | 2010-12-02 | Sumitomo Electric Ind Ltd | 光ファイバの製造方法 |
JP2017043528A (ja) * | 2015-08-28 | 2017-03-02 | 株式会社フジクラ | 光ファイバ素線の製造方法および製造装置 |
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JPH05139771A (ja) | 1991-11-22 | 1993-06-08 | Fujikura Ltd | 光フアイバ線引炉の制御方法 |
JPH11255534A (ja) * | 1998-03-10 | 1999-09-21 | Furukawa Electric Co Ltd:The | 光ファイバの線引き方法 |
WO2008062465A2 (en) * | 2006-10-17 | 2008-05-29 | Sterlite Optical Technologies Ltd. | Apparatus & method for drawing optical fiber having desired waveguide parameters and fiber produced thereby |
JP2009126755A (ja) * | 2007-11-26 | 2009-06-11 | Sumitomo Electric Ind Ltd | 光ファイバの線引き方法 |
JP2010269971A (ja) * | 2009-05-21 | 2010-12-02 | Sumitomo Electric Ind Ltd | 光ファイバの製造方法 |
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