JP4588420B2 - Optical fiber drawing device and control program thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable drawing control capable of generating no hunting, overshooting, etc., while restraining the makeup time (or accelerating time) at the non-steady state operation (transient state) of an optical fiber drawing unit. <P>SOLUTION: This is an optical fiber drawing unit in which a melt material from a preform is drawn while sending the preform to a drawing furnace where it is heated and melted, and the set value P1-P8 of the change quantity of stepwise drawing speed which depends on the change of the drawing speed is remembered, and the target change quantity &Delta;V<SB>dt</SB>_<SB>target</SB>, which changes continuously in response to the change quantity of the actual drawing speed v, is obtained by a linear interpolation calculation using the set value P1-P8 of the change quantity of the drawing speed, and the sending speed of the preform is controlled based on the difference of the target change quantity &Delta;V<SB>dt</SB>_<SB>target</SB>of the drawing speed and the actual drawing speed change quantity. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to an optical fiber drawing apparatus that manufactures an optical fiber from an optical fiber preform and a control program therefor, and more particularly to a target amount of change in a solid drawing speed according to a drawing speed (solid drawing speed) that changes from moment to moment. An optical fiber drawing apparatus which is continuously changed and has improved control performance by adjusting a base material feed speed based on a deviation between a target change amount of the solid drawing speed and an actual change amount of the solid drawing speed, and its control It is about the program.

In general, in an optical fiber drawing apparatus for manufacturing an optical fiber, a speed at which the optical fiber preform is continuously stretched after being heated in a drawing furnace provided in the optical fiber drawing apparatus (that is, a drawing speed), The quality of the optical fiber is closely related. For this reason, in order to obtain a high-quality optical fiber, various improvements for adjusting the drawing speed to an optimum speed have been advanced in the optical fiber drawing apparatus.
Normally, the drawing speed itself is feedback controlled so that the detected value of the outer diameter of the drawn optical fiber (bare optical fiber) follows the target value, so that the solid drawing speed becomes an appropriate speed. The control for this is performed indirectly by controlling the speed at which the optical fiber preform to be drawn is fed into the drawing furnace (hereinafter referred to as the preform feed speed).

For example, in the optical fiber drawing apparatus disclosed in Patent Document 1, the base material feed speed V _f is calculated by the following method, and the optical fiber base material is supplied to the drawing furnace at the calculated base material feed speed V _f. By doing so, the drawing speed is indirectly controlled to be an appropriate speed. Hereinafter, time t represents a time at a certain point during drawing, and drawing speed v (t) represents a solid drawing speed (actual drawing speed) at that time t.
In the optical fiber drawing apparatus disclosed in Patent Document 1, first, a speed V _f1 (hereinafter referred to as a base material feed base speed) which is a basic speed for feeding an optical fiber base material to a drawing furnace is set outside the optical fiber base material. Based on the diameter D (hereinafter referred to as the outer diameter of the base material), the target outer diameter d of the optical fiber after drawing (bare optical fiber) (hereinafter referred to as the target fiber outer diameter), and the target drawing speed v ₁ of the optical fiber Calculated according to equation (1). This equation (1) is an equation based on the law of mass invariance (preservation) established between the supplied optical fiber preform and the drawn optical fiber. The target drawing speed v ₁ is a drawing speed desirable for obtaining a high-quality optical fiber in relation to a coating process, which is a subsequent process, in a steady operation state, and is a speed given in advance.
V _f1 = v ₁ · d ² / D ² (1)

Next, the base material feed speed V _f (t) which is actually set by correcting the base material feed base speed V _f1 calculated by the equation (1) with a predetermined correction value (ΔV _f1 and ΔV _f2 ). calculate. Here, the correction value ΔV _f1 is obtained by multiplying the difference between the target drawing speed v ₁ and the solid drawing speed v (t) of the optical fiber by a predetermined positive coefficient K ₁ . Further, the correction value ΔV _f2 is multiplied by a predetermined positive coefficient K ₂ to a change amount per unit time of the actual drawing speed v (t), that is, acceleration v (t) −v (t−Δt). Is required.
The base material feed speed V _f (t) that is actually set is calculated by the following equation (2) that subtracts the correction value ΔV _f2 from the result of adding the correction value ΔV _f1 to the base material feed base speed V _f1 described above. Desired.
V _f (t) = V _f1 + ΔV _f1 −ΔV _f2
= V ₁ · d ² / D ² + K ₁ (v ₁ −v (t)) − K ₂ (v (t) −v (t−Δt)) (2)
By setting the base material feed speed V _f according to this equation (2), the solid drawing speed is indirectly controlled so as to follow the target drawing speed v ₁ . That is, when the solid drawing speed v is lower than the target drawing speed v ₁ , the base material feed speed V _f is accelerated according to the equation (2). As a result, the amount of melt of the optical fiber base material increases and the light after drawing Since the outer diameter (detected value) of the fiber tends to increase, the solid line drawing speed v is controlled to accelerate so that the outer diameter becomes the target fiber outer diameter d. Conversely, when the solid drawing speed v exceeds the target drawing speed v ₁ , the base material feed speed V _f is decelerated according to the equation (2), so that the outer diameter of the optical fiber becomes the target fiber outer diameter d. The pulling speed v is controlled so as to decelerate.
In the optical fiber drawing apparatus shown in Patent Document 1, the base material is set so that the speed at which the optical fiber base material is supplied to the drawing furnace becomes the base material feed speed V _f (t) obtained by the above-described calculation. A high-quality optical fiber is manufactured by rotating the feed motor.
JP-A-10-81538

By the way, the base material outer diameter D, the target fiber outer diameter d, and the target drawing speed v ₁ during steady operation are set in advance as operating conditions of the optical fiber drawing apparatus. In the optical fiber drawing apparatus, the base material feed base speed V _f1 obtained by the equation (1) is constant unless the operating condition is changed.
On the other hand, at the time of unsteady operation such as when the optical fiber drawing device is started up or at the end of operation, it is necessary to adjust the base material feed speed by greatly changing it. Therefore, at the time of unsteady operation, relying only on the method of making the base material feed base speed V _f1 constant in the above-described equation (2), the base material feed speed that requires a large adjustment width is inevitably required. Therefore, the correction terms ΔV _f1 and ΔV _f2 are to be corrected only, and the calculation weight of these correction terms increases.
However, the correction value ΔV _f1 is a correction term based on the excess or deficiency of the solid drawing speed with respect to the target drawing speed v ₁ , and the correction value ΔV _f2 is the dynamic correction, that is, the overshoot or deficiency of the correction tendency. It is related to the correction. For this reason, when the required adjustment range is large, the problem that the weight for the correction term becomes too large and the possibility of causing problems such as hunting and overshooting cannot be avoided.

In the optical fiber drawing apparatus disclosed in Patent Document 1, the values of the coefficients K ₁ and K ₂ are always optimized, which is a precondition for obtaining an accurate base material feed speed V _f (t). Although it is not difficult to imagine, it is extremely difficult to uniquely set the coefficients K ₁ and K ₂ that can deal with unsteady times when the drawing speed changes greatly, such as when the equipment is started up or when the operation is completed. It is. For this reason, when a failure such as hunting or overshoot occurs, the outer diameter and coating properties of the optical fiber are not constant, which causes a problem that the quality of the obtained optical fiber is reduced and the yield is reduced. In addition, if the induced hunting or overshoot is excessive, the drawing speed of the optical fiber drawing device cannot be controlled, and as a result, the optical fiber may be broken. Such problems in the unsteady operation state (transient situation) such as when the optical fiber drawing device is started up are caused by the operating conditions of the optical fiber drawing device such as the drawing speed and the correction term as described above. This occurs for the operating parameters to be determined.
In addition, as the diameter of the optical fiber preform increases, the length of the start-up line (or speed-up time) increases and the yield is becoming a problem. However, the length of the start-up line (or speed-up time) is increased. When acceleration is increased in order to shorten, there is a problem that there is a high possibility of causing problems such as hunting and overshooting at the rising end (near the target linear velocity).
Accordingly, the present invention has been made in view of the above circumstances, and the object of the present invention is to increase the length of the start-up line (or speed-up time) in the unsteady operation state (transient state) of the optical fiber drawing device. An object of the present invention is to provide an optical fiber drawing apparatus capable of performing stable drawing control without causing hunting or overshooting, and a control program therefor.

In order to achieve the above object, the present invention is an optical fiber drawing apparatus that draws an optical fiber by drawing an elution material from the base material while feeding the base material to a drawing furnace that is heated and melted. The drawing speed change amount step storage stores the stepwise drawing speed change amount setting value according to the drawing speed change and the stepwise base material feed base speed according to the drawing speed change. Derivation of a target drawing speed target change amount obtained by interpolation calculation using the drawing speed change amount setting value, and a target change amount of the drawing speed continuously changing according to a change in the actual drawing speed And a base material feed base speed corresponding to a change in the actual drawing speed is extracted from the drawing speed change amount stage storage means, and the base material feed base speed is compared with the target change amount of the drawing speed and the actual change. Correction based on comparison with the amount of change in drawing speed of Is constituted as an optical fiber drawing apparatus characterized by comprising anda preform feed speed adjusting means for adjusting the feed speed of the base material.
Also, a control program for causing a computer to control an optical fiber drawing apparatus that draws an optical fiber by drawing a base material to a drawing furnace that is heated and melted and drawing an elution material from the base material. A drawing speed change amount step for storing a stepwise drawing speed change amount setting value corresponding to a drawing speed change and a stepwise base material feed base speed corresponding to the drawing speed change. A line that continuously changes in accordance with a change in the actual drawing speed is obtained by reading out the setting value of the drawing speed from the storage means and performing an interpolation calculation using the drawing speed change setting. A drawing speed target change amount derivation process for obtaining a drawing speed target change amount, and the base material feed base speed corresponding to the actual drawing speed change are extracted from the drawing speed change amount stage storage means, The material feed base speed is the drawing speed A control program for causing a computer to execute a base material feed speed adjustment process for adjusting the base material feed speed by correcting based on a difference between the target change amount and the actual drawing speed change amount. It may be a thing. Here, the computer includes various devices including arithmetic means such as a personal computer, an FA computer, a microcomputer, and a PLC (Programmable Logic Controller).
Further, the drawing speed change amount stage storage means further stores a stepwise control gain according to a change in the drawing speed, and the base material feed speed adjustment means (process) The control gain corresponding to the change in drawing speed is extracted from the drawing speed change amount stage storage means, and the control gain is used to compare the target change amount of the drawing speed with the actual drawing speed change amount. It is desirable that the base material feed base speed be adjusted by calculating a base correction term and adjusting the base material feed base speed.
Further, the drawing speed change amount stage storage means further stores a stepwise control cycle in accordance with a change in the drawing speed, and the base material feed speed adjustment means (process) The control cycle corresponding to the change in drawing speed is extracted from the drawing speed change amount stage storage means, and the target change amount of the drawing speed and the actual drawing speed change amount are compared with each other in the period of the control cycle. It is also conceivable that the base material feed base speed is adjusted by calculating a base correction term and adjusting the base material feed base speed.

The drawing speed in the optical fiber drawing device is automatically adjusted (feedback control) so that the outer diameter of the optical fiber after drawing becomes the target outer diameter. When the optical fiber drawing device is started up or down, etc. In the unsteady operation state, the actual drawing speed varies greatly from moment to moment because the relationship between the amount of base metal supplied and the amount of elution in the furnace is not stable. For example, when starting up (an example of an unsteady operation state), if the amount of change in the actual drawing speed (drawing acceleration) is too large, overshoot or hunting occurs when shifting to steady operation, On the other hand, if the amount of change in the actual drawing speed is too small, the rising length (start-up time) becomes too long.
However, according to the configuration of the present invention, a stepwise change in the drawing speed corresponding to the change in the drawing speed is used as a parameter for determining the amount of change in the ideal drawing speed in such an unsteady operation state. The amount set value is stored in advance, and the target change amount of the drawing speed that continuously changes according to the actual drawing speed change (represents the transition of the ideal drawing speed change during unsteady operation) Is calculated by interpolation using the drawing speed change amount set value, and the base material feed speed is based on a comparison between the drawing speed target change amount and the actual drawing speed change amount. Therefore, the actual drawing speed is indirectly controlled to be an ideal change.
That is, when the actual drawing speed change amount is larger than the target drawing speed change amount (acceleration is large), if the base material feed rate is adjusted in the deceleration direction, the base material will be eluted. Since the outer diameter of the optical fiber after drawing tends to be reduced, the actual drawing speed is controlled in a direction to reduce the outer diameter so that the outer diameter becomes the target fiber outer diameter. Conversely, if the actual drawing speed change amount is smaller than the target drawing speed change amount (acceleration is small), the base material elution can be achieved by adjusting the feed speed of the base material in the acceleration direction. Increases so that the actual drawing speed is accelerated. As a result, the change in the actual drawing speed in the unsteady operation state changes ideally, and the stable length that does not cause hunting or overshooting while suppressing the rise length (or speed-up time). Drawing control is possible.

  As described above, according to the present invention, the target change amount of the drawing speed that continuously changes in accordance with the actual drawing speed that changes from moment to moment in the optical fiber drawing apparatus is obtained, and the target change amount is obtained. Since the base material feed speed is adjusted based on a comparison between the actual drawing speed and the amount of change in the actual drawing speed, hunting can be performed while suppressing the rise length (or acceleration time) even in unsteady operation. Stable line drawing control without causing overshoot or the like is possible. As a result, the wasteful time and material consumption that occur in the transitional state until the transition to the steady operation state is suppressed as much as possible to improve the yield, and the optical fiber breakage caused by large hunting and overshooting, etc. Can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
Here, FIG. 1 is a schematic configuration diagram of an optical fiber drawing apparatus X according to an embodiment of the present invention, and FIGS. 2 and 3 are data in which operation parameters used during start-up operation of the optical fiber drawing apparatus X are set. FIG. 4 is a graph showing an example of a table, FIG. 4 is a graph showing a relationship between a base material feed base speed and a solid drawing speed in the optical fiber drawing apparatus X, and FIG. 5 is a target drawing speed and a solid line in the optical fiber drawing apparatus X 6 is a graph showing the relationship with the drawing speed, FIG. 6 is a graph showing the relationship between the target change amount of the drawing speed and the solid drawing speed in the optical fiber drawing apparatus X, and FIG. 7 is a control in the optical fiber drawing apparatus X. 8 is a graph showing the relationship between the gain and the solid drawing speed, FIG. 8 is a graph showing the relationship between the control period and the solid drawing speed in the optical fiber drawing apparatus X, and FIG. 9 is a start-up operation of the optical fiber drawing apparatus X Drawing speed and time FIG. 10 is a trend graph of the base wire feed base speed, FIG. 10 is a trend graph of the solid line drawing speed and the target change amount of the drawing speed during start-up operation of the optical fiber drawing apparatus X, and FIG. It is a trend graph of the base material feed base speed and the actual base material feed speed during the lifting operation.

First, the configuration of an optical fiber drawing device X according to an embodiment of the present invention will be described with reference to FIG.
The optical fiber drawing apparatus X draws an optical fiber by drawing an elution material from the base material while feeding the optical fiber base material 2 to a drawing furnace 3 for heating and melting the optical fiber base material 2. Elements. That is, a base material feeding device 1 that holds the optical fiber preform 2 and feeds it to the drawing furnace 3, a drawing furnace 3 that heats the optical fiber preform 2, and a drawn optical fiber 4 (hereinafter, a bare optical fiber 4). 5) an outer diameter measuring device 5 for measuring the outer diameter, a cooling device 7 for cooling the bare optical fiber 4, a coating device 8 for applying a coating resin to the optical fiber, a resin curing device 9 for curing the applied coating resin, and a resin A take-up device 11 for taking up the optical fiber 10 drawn by the capstan 6, and the optical fiber drawing device X. A calculation unit 14 for performing the control calculation, an operation parameter storage unit 15 which is a non-volatile storage means for storing various operation parameters, and a motor 13 for rotating the base material feeding device 1 It is provided with a driver 12 for performing drive control of the motor 13.
The calculation unit 14 constitutes a microcomputer system, and the control calculation is performed by a predetermined control program stored in advance in a storage unit such as a ROM provided in the calculation unit 14 and a PLC ( This is performed by being executed by a calculation means (an example of a computer) such as a Programmable Logic Controller. In the present optical fiber drawing device X, control of the driver 12 and the like for controlling the motor 13 that is a drive source of the base material feeding device 1 is performed by the calculation unit 14 executing a control program.

Hereinafter, the manufacturing process of the optical fiber 10 in the optical fiber drawing apparatus X will be briefly described.
The optical fiber preform 2 held by the preform feeding apparatus 1 is heated and drawn in a drawing furnace 3 to become a bare optical fiber 4. At this time, the base material feed speed at which the optical fiber base material 2 is sent from the base material feed device 1 to the drawing furnace 3 is adjusted by rotating the motor 13 in accordance with a speed command signal transmitted from the driver 12. ing. A setting value of the base material feed speed corresponding to the speed command signal is determined by the calculation unit 14, which will be described later.
Here, in the optical fiber drawing device X, the outer diameter of the bare optical fiber 4 manufactured from the optical fiber preform 2 is determined by the take-up speed of the capstan 6. That is, the outside diameter of the drawn bare optical fiber 4 is measured online by the outside diameter measuring device 5, and the take-up speed of the capstan 6 is feedback-controlled so that the measurement result becomes the target outside diameter. By adjusting the take-up speed of the capstan 6 in this manner, the outer diameter of the bare optical fiber 4 is controlled to be constant (target outer diameter). The take-up speed of the capstan 6 is speed-adjusted (feedback control) by the calculation unit 14, and the take-up speed (rotational speed) of the capstan 6 is constantly measured by a tachometer (not shown). The actual drawing speed of the bare optical fiber 4 (hereinafter referred to as a solid drawing speed) is calculated by the calculation unit 14 from the measured value of the rotational speed of the capstan 6.
The bare optical fiber 4 thus manufactured is once cooled by the cooling device 7 and then coated with a coating resin on the surface thereof by the coating device 8. The coating resin applied here is cured by a resin curing device 9 to become an optical fiber 10. The optical fiber 10 is wound around a bobbin by a winding device 11 through a capstan 6.

Here, in the optical fiber drawing device X, operating parameters relating to the operating conditions (for example, a base material feed base speed, a target change amount of the drawing speed, which will be described later, a gain multiplied by a speed component related to a change amount of the solid drawing speed, The operation cycle and the like are stored in the operation parameter storage unit 15 in a stepwise manner corresponding to the solid line drawing speed set in a stepwise manner. The calculation unit 14 extracts (reads out) and applies the operation parameter corresponding to the solid line drawing speed calculated from the measured value of the rotation speed of the capstan 6 from the operation parameter storage unit 15. The operation parameter storage unit 15 is an example of the drawing speed change amount stage storage means in the present invention.
Further, the operation parameter read from the operation parameter storage unit 15 is applied to the following equation (3) by the calculation unit 14 according to the solid line drawing speed that sometimes changes during the operation of the optical fiber drawing device X: An operation for determining the base material feed speed and the like is performed. Then, the driver 12 described above is controlled according to the calculated result.
V _f (t) = V _f1 + K _P (ΔV _{dt — target−} ΔV _dt ) + K _I ∫ (ΔV _{dt — target} −ΔV _dt ) dt (3)
In Expression (3), V _f1 is a basic feed speed of the optical fiber preform 2 (hereinafter referred to as a preform feed base speed), K _p and K _I are control gains (hereinafter referred to as change proportional gain and change amount, respectively). ΔV _{dt — target} represents a target change amount of the drawing speed, and ΔV _dt represents a change amount of the solid drawing speed per predetermined unit time (hereinafter referred to as a solid drawing speed change amount). The solid line drawing speed change amount ΔV _dt is calculated by the calculation unit 14 based on the solid line drawing speed obtained from the measured value of the rotational speed of the capstan 6.

Next, the base material feed speed V _f calculated from the base material feed base speed V _f1 and the drawing speed target change amount ΔV _{dt — target} will be described with reference to FIGS. The drawing speed in the figure represents the solid drawing speed.
FIG. 2 shows the base material feed base speed V _f1 and the amount of change in the drawing speed, which are operating parameters used in the start-up operation of the optical fiber drawing apparatus X according to the embodiment of the present invention (an example of an unsteady operation state). Set value ΔV _{dt — S} (denoted as drawn acceleration set value in the figure), change proportional gain K _p and change integral gain K _I used in equation (3), proportional calculation used in equation (3) It is a figure showing an example of the data table set as a step-wise value according to the change of drawing speed (solid drawing speed), respectively, and the period of integration calculation. Here, the drawing speed change amount setting value ΔV _{dt — S} (drawing acceleration setting value) is an ideal drawing speed target change amount ΔV that is an ideal change amount (acceleration) of the actual drawing speed at the time of start-up. _This is a setting value for obtaining _{dt_target} .
FIG. 3 is a diagram showing a data table equivalent to the data table of FIG. 2, but a target drawing speed v ₁ is set instead of the base material feed base speed V _f1 in the data table of FIG. It is a thing. When the data table of FIG. 3 is used, the target drawing speed v ₁ set in this table is applied to the equation (1) based on the above-described law of mass invariance (preservation), and the base material feed base speed V _f1 Are calculated and set in stages.
4 to 8 are graphs showing the relationship between the operation parameters shown in FIGS. 2 and 3 and the solid line drawing speed.
Note that any one of the step change data (data table) of the operation parameter corresponding to the step change of the drawing speed (solid drawing speed) shown in FIG. 2 or FIG. Is remembered. Here, when the data table shown in FIG. 3 is stored in the operational parameter storage unit 15, the calculating section 14, the target line drawing speed v ₁ set in the data table (1) To obtain the base material feed base speed V _f1 (that is, the data table of FIG. 3 is equivalent to the data table of FIG. 2).
In this embodiment, each of these operation parameters is set in a stepwise manner in association with the solid line drawing speed divided into nine sections, but the number of sections is arbitrary. Smooth control is possible as the number of sections increases. Here, the threshold value of each section of the solid line drawing speed, and each operation parameter (base material feed base speed V _f1 or target drawing speed v ₁ , drawing speed change amount setting value ΔV _{dt — S} , proportional gain K The set values in the data table of _p and integral gain K _I , proportional calculation cycle and integral calculation cycle) may be input values (fixed values) input by the user from an operation unit that can be input, or a predetermined value. A variable value calculated by the calculation unit 14 from the above information may be used.

As shown in FIGS. 4, 5, 7, and 8, the calculation unit 14 includes a base material feed base speed V _f1 or a target drawing speed v ₁ , a proportional gain K _p and an integral gain K _I , a proportional calculation cycle. For each operation parameter of the integral calculation cycle, it is determined whether the solid line drawing speed obtained from the measured value of the rotational speed of the capstan 6 corresponds to the section (9 sections) set in the data table. Since the operation parameter corresponding to the corresponding section is read from the data table and used as it is, the operation parameter changes stepwise according to the change in the solid line drawing speed. These operating parameters (V _f1 , v ₁ , K _p , K _I , proportional calculation cycle and integral calculation cycle) are obtained for application to the equation (3).
On the other hand, the calculation unit 14 (an example of the drawing speed target change amount derivation means) is a drawing speed change amount setting value ΔV _{dt — S} (drawing speed) that is set stepwise according to changes in the drawing speed. The drawing speed change amount setting value corresponding to each of a plurality of threshold values defining a plurality of sections is read from the operation parameter storage unit 15 and linear interpolation calculation is performed using the read data. 6, the target change amount ΔV _{dt — target} of the drawing speed that continuously changes in accordance with the change of the solid drawing speed is obtained. Target amount of change [Delta] V _dt _ _target of this the drawing speed is also intended to be required to apply the formula (3).
Thus the drawing speed determined by linear interpolation of the target amount of change [Delta] V _dt _ _target on the vertical axis, when graphed solid drawing speed abscissa, a generally chevron graphical form as shown in FIG. 6 . Note that each of the break points P1 to P8 in the graph in FIG. 6 represents a drawing speed change amount setting value ΔV _{dt — S.}

Above manner, the base material feed base speed V _f1 obtained by applying the solid line drawing speed in the data table, the drawing speed of the target amount of change [Delta] V _dt _ _target, the proportional gain K _p and the integral gain K _I, A solid line drawing speed change amount ΔV _dt obtained based on each operation parameter of the proportional calculation cycle and the integral calculation cycle and a measured value of the rotational speed of the capstan 6 is applied to the above-described equation (3) by the calculation unit 14. A material feed speed _Vf is calculated. Then, the driver 12 described above is controlled according to the calculated result, and the supply control of the optical fiber preform 2 from the preform feeding apparatus 1 to the drawing furnace 3 is performed.
Here, the expression (3) indicates that the second term and the third term are used to feed the base material so that the difference between the drawing speed _target change amount ΔV _{dt — target} and the actual drawing speed change amount ΔV _dt is eliminated. It is a term of proportional calculation and integral calculation to adjust the speed. That is, by using the equation (3) to determine (calculate) the base material feed speed V _f by the calculation unit 14, the base material feed speed V _f becomes the drawing speed target change amount ΔV _{dt — target} and Adjustment is made based on a comparison with the actual drawing speed change amount ΔV _dt . Here, the calculation unit 14 and the driver 12 constitute an example of a base material feed speed adjusting means.

An example of the interpolation calculation of the target change amount ΔV _{dt — target} of the drawing speed by the calculation unit 14 is shown below.
According to the table of FIG. 2, for example, the base material feed base speed V _f1 and the target change amount ΔV _{dt — target} when the solid drawing speed v (t) = 500 m / min at a certain time point are as follows: It is as follows.
Base material feed base speed: 1.83 mm / min
Target change amount of drawing speed: 50+ (180-50) × (500−300) / (600−300) = 137 m / min ²
Further, according to the table of FIG. 3, for example, when the solid drawing speed v (t) = 500 m / min at a certain point in time, the target drawing speed v ₁ , the base material feed base speed V _f1, and the drawing speed target The change amount ΔV _{dt — target} is as follows.
Target drawing speed: 750 m / min
Target change amount of drawing speed: 50+ (180-50) × (500−300) / (600−300) = 137 m / min ²
At this time, when the base material outer diameter D set separately is 80 mm and the bare optical fiber outer diameter (target value) d is 0.125 mm, the base material feed base speed V _f1 is expressed by the following equation (1). The street is required.
V _f1 = ((0.125) ² / (80) ² ) × 750 = 1.83 mm / min

Next, a specific example of the calculation of the base material feed speed V _f executed by the calculation unit 14 will be described.
During drawing in the optical fiber drawing device X, if the drawing speed of the optical fiber at a certain time t is v (t) and the drawing speed dt time before the time t is v (t−dt), The amount of change in the solid line drawing speed per dt time, that is, the acceleration ΔV _dt is
ΔV _dt = v (t) -v (t-dt)
Is calculated.
According to the table of FIG. 2, for example, when the current drawing speed is 600 m / min and the drawing speed before 10 seconds (= dt) is 580 m / min, the acceleration ΔV _dt is
ΔV _dt = (600−580) × 60/10 = 120 m / min ²
It becomes.

Here, when the calculation for obtaining the change amount (acceleration) ΔV _dt of the solid line drawing speed is executed by the calculation unit 14 constituted by a PLC (Programmable Logic Controller), for example, it is as follows.
First, a solid drawing speed is acquired and accumulated at a cycle of about 100 msec, and moving average of about 10 to 100 accumulated latest drawing speed data is performed. The result of the moving average is used as a solid line drawing speed, and data for a fixed time dt including the current speed (latest moving average value) is always stored.
Next, by subtracting the drawing speed before dt time from the current drawing speed for this moving averaged solid drawing speed, the amount of change ΔV _dt in the solid drawing speed at a fixed time dt can be obtained. The amount of change in the solid line drawing speed is calculated at a cycle of about 100 msec, and the data of the latest solid line drawing speed change amount of about 10 to 100 is similarly moved and averaged, and the current amount of change in the solid line drawing speed ΔV _dt It is good.

Next, an example of the calculation of the base material feed speed V _f using the change amount proportional gain K _P , the change amount integral gain K _I , the proportional calculation cycle, and the integral calculation cycle will be described.
The change proportional gain K _P , change integral gain K _I , proportional calculation cycle and integral calculation cycle corresponding to the solid line drawing speed calculated from the rotation speed (measured value) of the capstan 6 are determined by the operation unit 14 by operating parameters. The set value of the data table corresponding to the solid line drawing speed that changes from time to time is read from the storage unit 15 and applied to equation (3) to calculate the base material feed speed V _f (t).
According to the data table of FIG. 2, for example, when the solid line drawing speed v (t) = 500 m / min at a certain time, the variation proportional gain K _P , the variation integral gain K _I , the proportional computation cycle, and the integral The calculation cycle is
Change proportional gain K _P : 8.0%
Change the amount of integral gain K _I: 4.0%
Proportional calculation cycle: 5.0 sec
Integral calculation cycle: 10.0 sec
These data are substituted into the equation (3), and the base material feed speed V _f (t) is calculated.
Here, the proportional term K _P (ΔV _{dt — target} −ΔV _dt ) and the integral term K _I ∫ (ΔV _{dt — target} −ΔV _dt ) dt in the expression (3) are the proportional calculation cycle (5.0 sec). ), And an integral calculation cycle (10.0 sec). As a result, it is possible to execute computations that make full use of response characteristics corresponding to the time of proportional computation and integral computation.

Next, the results of controlling the base material feeding apparatus 1 according to the base material feeding speed _Vf obtained by the above-described calculation in the optical fiber drawing apparatus X will be described with reference to the graphs shown in FIGS.
9 is a trend graph of the solid line drawing speed v and the base material feed base speed V _f1 during the start-up operation of the optical fiber drawing apparatus X, and FIG. 10 is a solid line drawing speed v and the line drawing during the start-up operation. 11 is a trend graph of the target change amount ΔV _{dt — target} of the speed, and FIG. 11 shows the base material feed base speed V _f1 and the actual base material feed speed (that is, the base material feed speed calculated by the computing unit 14) during the start-up operation. It is a trend graph of V _f ).
As shown in FIG. 9, the base material feed base speed V _f1 is temporarily high (2.93 mm / min in FIG. 9) in the initial stage of startup, that is, in the stage where the solid line drawing speed v is still low. After that, the vehicle is once decelerated to a low speed (1.22 mm / min), and then as the solid line drawing speed v approaches the target speed (1200 m / min) at the steady state, 2.93 mm / min) is accelerated stepwise (stepwise).
As described above, in the unsteady operation state, the speed V _f1 itself, which is the basis of the base material feed speed, is changed as needed in the unsteady operation state, so that the correction terms (relating to gains K ₁ and K ₂ in Equation (2)). It is not necessary to increase the weight for item (2) excessively, and problems such as hunting and overshooting can be prevented.
In the initial stage of startup, the base material feed base speed V _f1 is temporarily set to a high speed because the optical fiber preform 2 has not yet begun to melt in the drawing furnace 3 when the apparatus is started up. This is because, in the initial startup stage, it is necessary to temporarily speed up the feeding of the optical fiber preform 2 to promote melting of the preform.

Further, as shown in FIG. 10, the target amount of change [Delta] V _dt _ _target of drawing speed determined by the linear interpolation calculation is a chevron graphical form, which, at the time of start-up, the solid line drawing speed v is very slow In the interval from the initial stage to the intermediate speed (about 600 m / min in FIG. 10) on the way from the initial stage to the steady speed (1200 m / min in FIG. 10), the acceleration increases as the solid line drawing speed v increases. Is gradually increased from the state of 0 (or close to 0), and in the section from the intermediate speed to the steady speed, the acceleration is gradually decreased as the solid line drawing speed increases, and finally 0.
Then, the base material feed speed V _f is set so that the difference between the target change amount ΔV _{dt — target} of the mountain-shaped drawing speed and the actual change speed ΔV _dt of the drawing speed becomes 0 (zero). By adjusting (ie, adjusting) the base material feed base speed V _f1 according to equation (3) and setting (adjusting) the base material feed speed V _f , the amount of change (in the drawing line) (Acceleration) is controlled, and the rising curve of the solid line drawing speed v is stably controlled so as to be an ideal curve regardless of variations in the driving environment.
On the other hand, the base material feed speed V _f is changed to the drawing speed target change amount ΔV _{dt — target} and the actual drawing speed change amount as in the case of setting the base material feed speed V _f based on the expression (3). If adjustment is not made based on the comparison with ΔV _dt , the solid line drawing speed v during start-up operation will become a sudden rise curve that is unnecessarily abrupt or slower than the ideal rise curve due to variations in the operating environment. The startup operation is not stable.
Note that the deviation (difference) between the graph of the base material feed base speed V _f1 in FIG. 11 and the actual base material feed speed V _f graph is the correction term (change amount proportional gain K _p and change amount integral in equation (3)). it represents the correction amount by the term) concerning the gain K _I.
9 and 10 described above, in the start-up operation, the base material feed base speed V _f1 and the drawing speed target change amount ΔV _{dt — target} are changed according to the elapsed time after the start of operation. It seems to be equivalent even if it is made.
However, the ideal curve of the solid line drawing speed v (change in the target change amount of the solid line drawing speed) with the elapsed time after the start of operation as the horizontal axis is the operating condition (base material outer diameter D or bare optical fiber). Therefore, when setting the operation parameter data table according to the elapsed time after the start of operation, it is necessary to prepare the data table for each operation condition.
On the other hand, when the operation parameter data table is set according to the solid line drawing speed v, it is preferable in that the data table can be used universally regardless of the operation conditions.

1 is a schematic configuration diagram of an optical fiber drawing device X according to an embodiment of the present invention. The figure showing an example of the data table in which the operation parameter used at the time of starting operation of the optical fiber drawing apparatus X was set. The figure showing an example of the data table in which the operation parameter used at the time of starting operation of the optical fiber drawing apparatus X was set. The graph which showed the relationship between the base material feed base speed and the solid drawing speed in the optical fiber drawing apparatus X. The graph which showed the relationship between the target drawing speed and the solid drawing speed in the optical fiber drawing apparatus X. The graph which showed the relationship between the target variation | change_quantity of the drawing speed in the optical fiber drawing apparatus X, and a solid drawing speed. The graph which showed the relationship between the control gain and the solid drawing speed in the optical fiber drawing apparatus X. The graph which showed the relationship between the control period in the optical fiber drawing apparatus X, and a solid drawing speed. The trend graph of the solid line drawing speed and base material feed base speed at the time of start-up operation of the optical fiber drawing apparatus X. The trend graph of the solid wire drawing speed at the time of start-up operation of the optical fiber wire drawing apparatus X and the target change amount of the wire drawing speed. The trend graph of the base material feed base speed at the time of start-up operation of the optical fiber drawing apparatus X and the actual base material feed speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material feeder 2 ... Optical fiber base material 3 ... Drawing furnace 4 ... Bare optical fiber 5 ... Outer diameter measuring machine 6 ... Capstan 7 ... Cooling device 8 ... Coating device 9 ... Resin hardening device 10 ... Optical fiber element Wire 11 ... Winding device 12 ... Driver 13 ... Motor 14 ... Calculation unit 15 ... Operation parameter storage unit

Claims (6)

An optical fiber drawing apparatus that draws an optical fiber by drawing a base material to a drawing furnace that is heated and melted, and drawing an elution material from the base material,
A drawing speed change amount step storage means for storing a stepwise drawing speed change amount setting value corresponding to a drawing speed change and a stepwise base material feed base speed corresponding to the drawing speed change;
A drawing speed target change amount deriving means for obtaining a target change amount of the drawing speed that continuously changes in accordance with a change in the actual drawing speed by interpolation calculation using the drawing speed change amount setting value;
The base material feed base speed corresponding to the actual drawing speed change is extracted from the drawing speed change amount storage means, and the base material feed base speed is set to the target change amount of the drawing speed and the actual drawing speed. A base material feed speed adjusting means for adjusting a feed speed of the base material by adding a correction amount based on a comparison with a speed change amount;
An optical fiber drawing device comprising: The drawing speed change amount stage storage means further stores a stepwise control gain according to a change in drawing speed,
The base material feed speed adjustment means extracts the control gain corresponding to the actual drawing speed change from the drawing speed change amount storage means, and uses the control gain to change the drawing speed target change amount. 2. The feed rate of the base material is adjusted by calculating a correction amount based on a comparison between the actual drawing speed change amount and the actual drawing speed change amount, and adding the correction amount to the base material feed base speed. The optical fiber drawing apparatus as described. The drawing speed change amount stage storage means further stores a stepwise control cycle corresponding to a change in drawing speed,
The base material feed speed adjusting means extracts the control cycle corresponding to the actual drawing speed change from the drawing speed change amount storage means, and the target change amount of the drawing speed in the control cycle period. 2. A feed amount of the base material is adjusted by calculating a correction amount based on a comparison between the actual drawing speed change amount and the actual drawing speed change amount, and adding the correction amount to the base material feed base speed. The optical fiber drawing apparatus according to any one of 2 above. A control program for causing a computer to execute control of an optical fiber drawing apparatus that draws an optical fiber by drawing a base material to a drawing furnace that is heated and melted and drawing an elution material from the base material. And
From the drawing speed change amount storage means for storing the stepwise drawing speed change amount setting value according to the drawing speed change and the stepwise base material feed base speed according to the drawing speed change. By reading out the drawing speed change amount setting value and performing interpolation calculation using the drawing speed change amount setting value, the drawing speed target that changes continuously according to the actual drawing speed change A drawing speed target change derivation process for obtaining a change amount;
The base material feed base speed corresponding to the actual drawing speed change is extracted from the drawing speed change amount stage storage means, and the base material feed base speed is calculated from the drawing speed target change amount and the actual drawing speed. A base material feed speed adjustment process for adjusting the feed speed of the base material by adding a correction amount based on a comparison with the speed change amount;
A control program that causes a computer to execute. The drawing speed change amount stage storage means further stores a stepwise control gain according to a change in drawing speed,
The base material feed speed adjustment processing extracts the control gain corresponding to the actual drawing speed change from the drawing speed change amount storage means, and uses the control gain to change the drawing speed target change amount. 5. The feed rate of the base material is adjusted by calculating a correction amount based on a comparison between the actual drawing speed change amount and the actual drawing speed change amount, and adding the correction amount to the base material feed base speed. The control program described. The drawing speed change amount stage storage means further stores a stepwise control cycle corresponding to a change in drawing speed,
The base material feed speed adjustment processing extracts the control cycle corresponding to the actual drawing speed change from the drawing speed change amount storage means, and the target change amount of the drawing speed in the control cycle period. 5. A feed amount of the base material is adjusted by calculating a correction amount based on a comparison between the actual drawing speed change amount and the actual drawing speed change amount, and adding the correction amount to the base material feed base speed. 6. The control program according to any one of 5.

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