Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02400331 2002-08-14
Specification
Manufacturing apparatus for metal sheathed optical fiber cable and method
thereof
Technical field
The present invention relates to a manufacturing apparatus for manufacturing
metal
sheathed optical fiber cables, for example, used in optical-fiber combined
overhead ground
wires, and more particularly, to a manufacturing apparatus and method for
forming a metal
tube from a metal tape, inserting an optical fiber into the formed metal tube,
filling gaps
between the optical fiber and metal tube with a viscous material, and thus
manufacturing
metal sheathed optical fiber cables.
Related art
A metal sheathed optical fiber cable is manufactured by forming a metal tape
into a
tube, welding joint portions of the metal tape, and thereby manufacturing a
metal tube,
while inserting an optical fiber into the metal tube through a guide pipe
inserted into the
metal tube so that a front end of the guide pipe is located at a position
ahead of a welding
position (for example, as described in Japanese Laid-Open Patent Publication
No.4-350808
(1992)). Such an optical fiber cable is manufactured, for example, using an
apparatus as
shown in Fig. 1. In a manufacturing apparatus 1, a metal tape 2, for example,
stainless steel
tape is formed into a tube using a plurality of forming rolls 3, joint
portions on opposite
ends of the metal tape 2 are welded using a welder 5, and thus a metal tube 6
is formed.
While forming the metal tube 6, an optical fiber 11 and a viscous material 12,
for example,
liquid synthetic resin are introduced inside the metal tube 6 using a guide
pipe 4, and
thereby an optical fiber cable is manufactured.
The guide pipe used as described above protects optical fibers from damage due
to
welding heat in welding the tape by Tig welding, for example. Further, the
guide pipe is
often used to feed a waterproofing viscous material, as well as the optical
fiber, inside the
metal tube.
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As shown in Fig. 1, the optical fiber 11 is supplied through guide pipes 4 and
7, and
the viscous material 12 is supplied from a tank 9 using a pump 10 to the guide
pipe 4
through a supply pipe 8. The guide pipe 4 extends ahead (in the direction of
feeding the
optical fiber) of a position where the metal tube 6 is welded, and protects
optical fibers and
viscous material from damage due to heat caused by the welding.
In a conventional apparatus, since a joint of the metal tape that is running
to form a
tube is welded using a welding torch disposed at a fixed position, a portion
of the guide
pipe exactly under the welding torch tends to cause damage by heat. Then, it
may happen
that the heat bores a hole in the guide pipe, whereby the sheath of the
optical fiber inside the
pipe melts by the heat and/or the viscous material boils and flows outside.
Even if the
welding heat does not cause a hole, there arises a case that the guide pipe
transforms by the
heat and a distance between the metal tape and guide pipe changes, thereby
providing the
welding with inconveniences.
In view of the foregoing, a first object of the present invention is to
provide a
manufacturing apparatus for a metal sheathed optical fiber cable to overcome
the above
problems. The viscous material filled into gaps between the optical fiber and
metal tube
fixes the optical fiber in the metal tube, and protects the optical fiber from
water and from
side pressure.
The aforementioned viscous material has a high viscosity, and cannot be
supplied by
a predetermined pressure at the time of starting manufacturing. When the pump
10 is
started to work, the viscous material does not flow from the guide pipe 4 into
the metal tube
6 immediately after the pump 10 is actuated, and gradually moves inside the
metal tube 6
from the guide pipe 4 after a time elapses. Then, the viscous material starts
flowing stably
from the guide pipe 4 to the metal pipe 6 at a set flow rate Rs (for example,
40g/min.) after
two or more minutes, for example, elapses after starting the pump 10.
As described above, since it takes a time to start stably supplying the
viscous
material to the metal pipe 6 after starting to actuate the pump 10, there
arises a problem
such that defective portions are manufactured in which the viscous material is
not supplied
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or poor inside the metal tube 6 of the optical fiber cable, at an earlier time
immediately after
starting manufacturing of the optical fiber cable.
Therefore, a second object of the present invention is to provide an optical
fiber
cable manufacturing apparatus capable of stably supplying the viscous material
to the metal
tube immediately after starting manufacturing of optical fiber cable, and
reducing failures
caused by the viscous material at an earlier stage of the manufacturing.
Thus, in order to overcome the above problems, the present invention aims to
provide a metal sheathed optical fiber cable manufacturing apparatus with
stable
performance and capability.
Summary of the invention
The present invention provides a metal sheathed optical fiber cable
manufacturing
apparatus which comprises:
(1) a forming apparatus that forms a metal tape into a tube so as to obtain a
metal tube
to sheathe an optical fiber;
(2) a supplying apparatus that supplies to the metal tube a viscous material
that protects
the optical fiber inserted into the metal tube;
(3) a bonding apparatus which is disposed on a stage movable forwardly and
backwardly and which bonds joint portions of the metal tape formed into a
tube; and
(4) a pipe-shaped guide that guides the metal tape and protects the optical
fiber in
bonding the metal tape formed into a tube.
Further, the present invention provides a metal sheathed optical fiber cable
manufacturing method that comprises the steps of
( 1 ) forming a metal tape into a tube so as to obtain a metal tube to sheathe
an optical
fiber;
(2) guiding a viscous material that protects the optical fiber inserted into
the metal tube
into a guide pipe that protects the optical fiber inserted into the metal tape
formed into a
tube; and
(3) bonding joint portions of the metal tape formed into a tube while moving
forwardly
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and backwardly.
Brief descriptions of the drawings
Fig. 1 is a diagram showing a schematic configuration of an optical fiber
cable
manufacturing apparatus;
Fig. 2 is a side view showing an embodiment of a metal sheathed optical fiber
cable
manufacturing apparatus according to the present invention;
Fig. 3 is a graph showing a preferable relationship between a line speed and a
travel
speed of a welding torch in implementing the present invention;
Fig. 4 is a graph showing a preferable embodiment of a travel speed of a
welding
torch that travels periodically in the present invention;
Fig. 5 is a graph showing relationships between elapsed time after starting to
manufacture optical fiber cables and a discharge flow rate of a viscous
material to a metal
tube in an embodiment of the present invention and in a conventional case;
Fig. 6 is a diagram showing an example of pressure control of an apparatus for
supplying the viscous material in the present invention;
Fig. 7 is a flowchart illustrating the example of pressure control of the
apparatus for
supplying the viscous material;
Fig. 8 is a diagram to explain actuation amount control of a pressurizing pump
including a pre-pressurizing control unit in another embodiment of the present
invention;
and
Fig. 9 show graphs illustrating an example of pressure control of the viscous
material in another embodiment of the present invention.
Detailed description of the preferred embodiments
Embodiments of the present invention will be described specifically below.
A first embodiment of the invention is a metal sheathed optical fiber cable
manufacturing apparatus that comprises:
(1) a forming apparatus that forms a metal tape into a tube so as to obtain a
metal tube
to sheathe an optical fiber;
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(2) a supplying apparatus that supplies to the metal tube a viscous material
that protects
the optical fiber inserted into the metal tube;
(3) a bonding apparatus which is disposed on a stage movable forwardly and
backwardly and which bonds joint portions of the metal tape formed into a
tube; and
(4) a pipe-shaped guide that guides the metal tape and protects the optical
fiber in
bonding the metal tap formed into a tube.
A second embodiment of the invention is the manufacturing apparatus in which
the
forming apparatus is a roll forming apparatus provided with a plurality of U-
shaped caliber
rolls.
A third embodiment of the invention is the manufacturing apparatus in which
the
viscous material for protecting the optical fiber is a liquid synthetic resin.
A fourth embodiment of the invention is the manufacturing apparatus in which
the
bonding apparatus is a welding apparatus.
A fifth embodiment of the invention is the manufacturing apparatus in which
the
welding apparatus is a Tig welding apparatus.
A sixth embodiment of the invention is the manufacturing apparatus in which
the
welding apparatus is a plasma welding apparatus.
A seventh embodiment of the invention is the manufacturing apparatus in which
the
welding apparatus is a laser welding apparatus.
An eighth embodiment of the invention is the manufacturing apparatus in which
a
guide roll that guides the metal tape to be welded into a tube is disposed in
the vicinity of
the stage.
A ninth embodiment of the invention is the manufacturing apparatus in which
the
stage is provided with a guide roll that guides the metal tape to be welded
into a tube.
A tenth embodiment of the invention is the manufacturing apparatus in which
the
stage provided with the bonding apparatus travels forwardly and backwardly in
predetermined cycles in a direction of feeding the optical fiber, while
welding joint
portions of the metal tape formed into a tube.
An eleventh embodiment of the invention is the manufacturing apparatus in
which a
forward speed and a backward speed of the stage are not greater than a line
speed of the
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optical fiber.
A twelfth embodiment of the invention is the manufacturing apparatus in which
the
forward speed of the stage is greater than the backward speed of the stage.
A thirteenth embodiment of the invention is the manufacturing apparatus in
which
the supplying apparatus is provided with a tank to store the viscous material,
a pipe line that
supplies the viscous material from the tank to the metal tape that is formed
but not welded
yet, a pressurizing pump provided at a middle portion of the pipe line, and a
valve that
controls a supply amount of the viscous material.
A fourteenth embodiment of the invention is the manufacturing apparatus in
which a
pressure sensor for measuring a pressure of the viscous material is provided
between the
pump and the valve.
A fifteenth embodiment of the invention is the manufacturing apparatus in
which the
pressurizing pump is operated during a predetermined period of time using a
pressure
higher than a predetermined steady supply pressure based on a signal from the
pressure
sensor before manufacturing of the optical fiber cable is started.
A sixteenth embodiment of the invention is the manufacturing apparatus
provided
with a second pipe line that is provided between the pump and the valve and
that supplies
the viscous material stably through a control valve, and with a pre-
pressurizing control
apparatus that controls pressures of the second pipe line and the control
valve.
A seventeenth embodiment of the invention is the manufacturing apparatus
further
provided with a control apparatus that controls an actuation amount of the
pressurizing
pump based on the pressure sensor for measuring pressures of the viscous
material and the
pump.
An eighteenth embodiment of the invention is a metal sheathed optical fiber
manufacturing method that comprises the steps of
( 1 ) forming a metal tape into a tube so as to obtain a metal tube to sheathe
an optical
fiber;
(2) guiding a viscous material to be inserted into the metal tape formed into
a tube into a
guide pipe that protects the optical fiber inserted into the metal tape formed
into a tube; and
(3) bonding joint portions of the metal tape formed into a tube while moving
forwardly
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and backwardly.
A nineteenth embodiment of the invention is the manufacturing method in which
the
step of forming is performed in a roll forming apparatus provided with a
plurality of U-
shaped caliber rolls.
A twentieth embodiment of the invention is the manufacturing method in which
the
metal tape is bonded using a welding method.
A twenty first embodiment of the invention is the manufacturing method in
which
the welding method is a Tig welding method.
A twenty second embodiment of the invention is the manufacturing method in
which the welding method is a plasma welding method.
A twenty third embodiment of the invention is the manufacturing method in
which
the welding method is a laser welding method.
A twenty fourth embodiment of the invention is the manufacturing method in
which
joint portions of the metal tape formed into a tube are bonded while a bonding
position
moves forwardly and backwardly in predetermined cycles in a direction of
feeding the
optical fiber.
A twenty fifth embodiment of the invention is the manufacturing method in
which a
forward speed and a backward speed are not greater than a line speed of the
optical fiber.
A twenty sixth embodiment of the invention is the manufacturing method in
which
the forward speed is greater than the backward speed.
A twenty seventh embodiment of the invention is the manufacturing method in
which the viscous material is supplied while a pressure of the viscous
material inside a
supply pipe is maintained at a predetermined pressure.
A twenty eighth embodiment of the invention is the manufacturing method in
which
the pressure for supplying the material is maintained at a pressure higher
than a
predetermined steady supply pressure before manufacturing of the optical fiber
is started.
A twenty ninth embodiment of the invention is the manufacturing method in
which
the pressure for supplying the viscous material is controlled by actuation
amount of a
pressurizing pump to be maintained, while being measured.
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The present invention will be described below using embodiments with reference
to
accompanying drawings. However, the present invention is not limited to the
embodiments, and includes any combinations thereof within the scope disclosed
in the
embodiments.
Embodiments of the present invention will be described specifically below with
reference to drawings. As described previously, Fig. 1 shows a typical
manufacturing
apparatus. In the conventional manufacturing apparatus, a fixed welding torch
welds a joint
portion of a metal tape that is formed into a tube by U-shaped caliber rolls.
In an
embodiment of the present invention as shown in Fig. 2, the metal tape 2, for
example, a
stainless steel tape or aluminum tape, is formed into a tubular shape with a
predetermined
form by caliber rolls 3 provided with a caliber to form the tape into a tube;
usually cylinder,
or tube with an oval-shaped cross section. Then, a welding torch, for example,
the welding
torch S bonds joint potions of the metal tape 2 formed into a tubular shape. A
bonding
method is selected as appropriate from among Tig welding, plasma welding and
laser
welding using for example, an excimer laser, YAG laser or C02 laser. A welded
metal tube
6 is fed in the direction of arrow P at a line speed of, for example, about l
Om/min. In this
figure, a guide pipe 13 is disposed so that a frond end of the pipe 13 is
located in the metal
tube 6 at a position ahead (right side of the figure) of the welding torch 5.
The optical fiber
11 is fed into the metal tube 6 through the guide pipe 13, and a viscous
material 12 is fed
into the metal tube 6 through the guide pipe 4. In Fig. 2, since the guide
pipes 4 and 13 are
provided separately, the guide pipe 4 also has the function of protecting the
optical fiber
from the welding torch. In addition, as shown in Fig. 1, the guide pipe 4 may
supply both
the optical fiber 11 and viscous material 12.
In the apparatus of the present invention, when metal sheathed optical fiber
cables
are manufactured, a welding apparatus, for example, the welding torch 5
performs welding,
while reciprocating (traveling between solid line and broken line) along the
joint of the
metal tape 2 formed into a tube. In this way, since a position heated by the
welding torch 5
of the guide pipe 13 varies in a longitudinal direction, a possibility that
the pipe 13 causes
damage due to heat greatly decreases as compared to the conventional case
where the pipe
13 is locally heated. As a result, since the life of the guide pipe 13
increases, it is possible
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to greatly reduce the frequency of exchange of the guide pipe 13, and to
manufacture metal
sheathed optical fiber cables with longer lengths. Further in the
manufacturing apparatus,
since the guide pipe 13 does not move, it is possible to feed the optical
fiber l l smoothly,
and therefore the risk is reduced of degrading the optical fiber 11.
Various apparatuses are considered as a device to cause the welding torch 5 to
reciprocate. For example, it may be possible that on a base 51 is provided a
stage 50
slidable in the direction in which the metal tube 6 is moving; the welding
torch 5 and a
guide roll 53 are provided on the stage 50, and the stage 50 is operated to
reciprocate by an
actuator 52 fixed to the base 51 with the welding torch 5 always located on a
joint of the
metal tape in the relationship between positions of the welding torch 5 and
guide roll 53.
The stage 50 is, for example, operated to reciprocate distances of 100mm at a
speed of
about Smm/min. Thus manufacturing metal sheathed optical fiber cables
continuously for
about fifteen hours resulted in no hole in the guide pipe 13. In the
conventional apparatus
with the welding torch fixed, a hole was bored in the guide pipe after three
to five hours.
Thus, the apparatus of the present invention provides a greatly increased
life.
In addition, in Fig. 2 the guide roll 53 is configured to move along with the
welding
torch 5, but may be supported by another supporting member different from that
of the
welding torch 5. In this case, the guide roll 53 may be fixed, or may be
provided movable
in the longitudinal direction of the metal tube.
It is preferable as shown in Fig. 3 to set a travel speed of the welding torch
5 (travel
speed of the stage 50) to be lower than and proportional to a line speed
(moving speed of
the metal tube 16). It is because a high line speed results in an increased
amount of heat
provided from the welding torch, and therefore it is necessary to move the
welding torch
faster to reduce the effect of the welding heat on the guide pipe to low as
possible.
It is preferable as shown in Fig. 4 to control the travel speed of the welding
torch 5
so that the speed at which the welding torch 5 is traveling in the direction
the metal tube is
moving is higher than the speed at which the welding touch S is traveling in
the opposite
direction. Thus controlling decreases a difference between a relative speed
(forward
welding speed) between the welding torch 5 and the metal tube 6 when the
welding torch is
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traveling in the direction the metal tube is moving and a relative speed
(backward welding
speed) between the welding torch 5 and metal tube 6 when the welding torch is
traveling in
the opposite direction. As a result, welding conditions become stable, and it
is possible to
obtain excellent welding states over the full length.
As described above, according to the present invention, the welding torch 5
performs welding while reciprocating along the joint of the metal tape,
whereby it is
possible to reduce damage of the guide pipe 13 due to the welding heat, and to
increase the
life of the guide pipe 13. In this way, the frequency of exchange of the guide
pipe
decreases, and therefore it is possible to increase the manufacturing
efficiency and to
manufacture metal sheathed optical fiber cables with longer lengths. Further,
since the
guide pipe is allowed to stand still, it is possible to avoid damage of the
optical fiber due to
the movement of the guide pipe, and to decrease an occurrence rate of
defective piece.
Further, the manufacturing apparatus 1 for optical fiber cable of the present
invention provides a specific supplying apparatus for supplying the viscous
material 12. In
the manufacturing apparatuses disclosed in Figs. 1 and 2 as previously
explained, the pump
supplies the viscous material to the supply pipe 8 which is provided with a
first valve 21
and a pressure control unit, as shown in Fig. 6, which are to control the
pressure as an
open/close apparatus for controlling open/close of a passage located
downstream from the
pump 10 during a predetermined period of time after starting manufacturing.
One of the major features in this embodiment is to actuate pump 10 with the
first
valve 21 closed before actually starting to manufacture optical fiber cables
as a pre-
pressuring operation for increasing the pressure of the viscous material
inside the supply
pipe 8 between the pump 10 and first valve 21, and then open the first valve
21 to start the
manufacturing of optical fiber cable. In addition, any manufacturing methods
are available
after starting the manufacturing, and explanations of the methods are omitted
herein.
Although it may be possible to manually perform the actuation of the pump 10
and
open/close operation ofthe first valve 21 associated with the pre-pressurizing
of the viscous
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material 12, an example will be described of configurations for automatically
controlling
the actuation of the pump 10 and open/close operation of the first valve 21.
For example, in a first example of pressure control, the viscous-material
supply pipe
8 between the pump 10 and first valve 21 is provided with a pressure sensor
apparatus 22
that detects the pressure inside the pipe line. The pressure control unit 20
to control the
optical fiber cable manufacturing apparatus 1 automatically controls the
operation of pre-
pressurizing of the viscous material.
For example, the pressure control unit 20 for the viscous material is provided
with a
configuration for fetching information of pressure sensor apparatus 22, and
using the
fetched information, automatically controlling the pump 10 and first valve 21
according to
control procedures shown in the flowchart in Fig. 7. In other words, when
detecting an
instruction for starting the apparatus operation, for example, based on
operation information
of an operation start button by an operator (step S1 in Fig. 7), the pressure
control unit 20
starts to actuate the pump 10 with the first valve 21 closed (step S2), and
thus increases the
pressure of the viscous material inside the viscous material supply pipe 8
between the pump
and first valve 21.
Pressure control unit 20 fetches detection values from the pressure sensor
apparatus
22 sequentially (step S3), and compares each fetched detection value with a
set pressure
value to determine whether the detection value reaches the set pressure value
(step S4).
When the pump 10 is started to operate with the first valve 21 closed, as
shown by
chained line in Fig. 5, the pressure inside the viscous material supply pipe 8
gradually
increases as time elapses. Then, a$er the viscous material is supplied to the
metal tube 6
from the guide pipe 4 stably at a set flow rate Rs, the pressure of the
viscous material inside
the viscous material supply pipe 8 is maintained at an almost constant
pressure Ps.
The required pressure Ps (pressure value required for stably supplying the
viscous
material from the guide pipe 4 to the metal tube 6 at the set flow rate Rs) is
obtained by
calculation, experiment, etc. The obtained pressure Ps is given in advance as
the above-
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mentioned set pressure value to the pressure control unit 20. Pressure control
unit 20
compares the set pressure Ps with a detection value of pressure sensor
apparatus 22, and
when determining that the detection value of the pressure sensor apparatus 22
reaches the
set pressure Ps, opens the first valve 21 (step SS). In this example, at the
same time as
opening the valve 21, the actuation of rolls 3 and supply of optical fiber
from the optical
fiber supply pipe 7 to guide pipe 4 are started, thus starting to manufacture
optical fiber
cables.
According to the first example of pressure control, the viscous material
supply pipe
8 is provided in its portion located downstream from the pump 10 with the
first valve 21,
and the pump 10 is actuated with the first valve 21 closed to perform the pre-
pressurizing
operation for increasing the pressure of the viscous material inside the
supply pipe 8
between the pump 10 and first valve 21 before starting to manufacture optical
fiber cables.
It is thereby possible to stably supply the viscous material into the metal
tube 6 from the
guide pipe 4 nearly at set flow rate Rs, as shown in Fig. 5, after opening the
first valve 12
and starting to manufacture optical fiber cables. As a result, it is possible
to eliminate
almost all of failures at an earlier stage of manufacturing optical fiber
cables and thus
eliminate waste.
Next, a second example of pressure control different from the first example
will be
described. In addition, in the description in this example, the same
structural components
as in the first example of pressure control are assigned the same reference
numerals to omit
overlapping explanations thereof.
In an optical fiber cable manufacturing method in the second example of
pressure
control, as shown in Fig. 8, the viscous material supply pipe 8 between the
pump 10 and
first valve 21 is provided with a pressure adjusting apparatus 34 and a second
valve 31, for
example. The pressure adjusting apparatus 34 controls a pipe line 32 with an
inner
diameter almost equal to that of the viscous material supply pipe 8, a pipe
line 33 with an
inner diameter which is thinner than that of the pipe line 32 and almost equal
to that of the
guide pipe 4, and the second valve 31 provided between pipe lines 32 and 33.
In the
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pressure adjusting apparatus 34, one end ofthe pipe line 32 is communicated to
the viscous
material supply pipe 8 between the pump 10 and first valve 21, the other end
of the pipe
line 32 is connected to one end of the pipe line 33, and the other end of the
pipe line 33 may
be connected to, for example, tank 9 for storing the viscous material.
Further, it may be
possible to connect the other end of the pipe line 33 to the supply pipe 8 and
circulate the
viscous material to control the pressure.
Since the pressure adjusting apparatus 34 is connected to the pipe line 32 and
pipe
line 33 thinner than the pipe line 32, by actuating the pump 10 with the first
valve 21 closed
and the second valve 31 opened, it is possible to increase the pressure of the
viscous
material inside the supply pipe 8 between the pump 10 and first valve 21, and
to stabilize
the pressure to a predetermined pressure value set in advance even when the
pressure of the
viscous material varies. In the second example of pressure control, the set
pressure Ps
(pressure value required for stably supplying the viscous material from the
guide pipe 4 to
the metal pipe 6 at the set flow amount Rs) illustrated in the first example
of pressure
control is set as the above-mentioned set pressure.
In the second example of the pressure control, by performing the pre-
pressurizing
operation on the viscous material before starting to manufacture optical fiber
cables, the
pressure of the viscous material is increased inside the supply pipe 8 between
the pump 10
and first valve 21. Then, after the pressure of the viscous material is
stabilized by the
pressure adjusting material 34, the first valve 21 is opened, and at the same,
the
manufacturing of optical fiber cable is started. In addition, any
manufacturing methods are
available after starting the manufacturing, and explanations of the methods
are omitted
herein.
Also in the second example of pressure control, since the manufacturing of
optical
fiber cable is started after performing the pre-pressurizing operation on the
viscous material,
it is possible to eliminate almost all of failures caused by the viscous
material at an earlier
stage of the manufacturing, as in the first example of control pressure.
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As in the first example of pressure control, although in the second example of
pressure control it may be possible to manually perform the actuation of the
pump 10 and
open/close operations of the first valve 21 and second valve 31 associated
with the pre-
pressurizing of the viscous material, an example will be described of
configurations for
automatically controlling the actuation of the pump 10 and open/close
operations of the
valves 21 and 31.
The optical fiber cable manufacturing apparatus explained in the second
example of
pressure control is provided with a pre-pressurizing control unit 30, as well
as the second
valve 31. Except the control unit 30 and valve 31, a configuration of the
apparatus in the
second example is almost same as that of the apparatus explained in the first
example. In
addition, in the second example of pressure control, if the pressure is set in
advance to a
value same as described in the first example of pressure control, it is not
necessary to
provide the pressure sensor apparatus 22.
In the second example of pressure control, when the optical fiber cable
manufacturing apparatus 1 stops its operation, the first valve 21 is closed
and the second
valve 31 is opened. For example, when detecting an instruction for starting
the apparatus
operation, the pre-pressur'~zing control unit 30 starts to actuate the pump 10
while keeping
the first valve 21 closed and the second valve 31 opened, and the thus
actuated pump 10
increases the pressure of the viscous material inside the viscous material
supply pipe 8.
When a predetermined valve opening condition is satisfied, the pre-
pressurizing
control unit 30 closes the second valve 31 and opens the first valve 21.
Concurrently, the
manufacturing of optical fiber cable is started. The first valve 21 and second
valve 31 may
be a general mechanical valve or electromagnetic valve. The control apparatus
34 may be a
mechanical handle or a control apparatus that operates electromagnetically.
The valve opening condition is to indicate that the pressure of the viscous
material
inside the supply pipe 8 is maintained at a set pressure by the pre-
pressurizing control unit
30. For example, since a time is almost determined which is required for the
pressure of the
viscous material inside the supply pipe 8 to be stabilized nearly at a set
pressure by the
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second valve 31 after starting to actuate the pump 10, such a time was
obtained in advance
and a lapse of the time (for example, two minutes) after starting to actuate
the pump 10 is
given as the valve opening condition.
The pre-pressurizing control unit 30 as described above enables automatic
operation
of the pre-pressuring before a start of the manufacturing of optical fiber
cable.
In addition, the second valve 31 is only required to be provided with a
configuration
for adjusting the pressure of the viscous material inside the viscous material
supply pipe 8
between the pump 10 and first valve 21 when the pre-pressurizing operation on
the viscous
material is performed before starting the manufacturing of optical fiber
cable, and is not
limited to a mechanical valve. For example, instead of pipe line 33 thinner
than the pipe
line 32, the pipe line 32 may be provided with a flow-rate control apparatus
such as a
needle valve that is capable of variably controlling a flow rate of the
viscous material in the
pipe line 32. For example, when a needle valve is provided, the degree of open
of the
needle valve is controlled so that the pressure of the viscous material inside
the supply pipe
8 between the pump 10 and first valve 21 becomes a set pressure at the time of
the pre-
pressurizing operation on the viscous material.
A third example of pressure control will be described below. In the optical
fiber
cable manufacturing apparatus in the third example of pressure control, in the
case where
optical fiber cables are manufactured using the optical fiber cable
manufacturing apparatus
as shown in Fig. 1 or 2 previously mentioned, the pump 10 is actuated by
actuation amount
larger than a pump actuation amount Js of steady operation, as shown in Fig.
9, in
manufacturing optical fiber cables. In this way, the rise in the pressure of
the viscous
material, as shown by solid line A, inside the supply pipe 8 is enhanced as
compared to the
rise in the pressure of the viscous material, as shown by broken line B, in
the conventional
case. Therefore, it is possible to perform fast stabilization of supply of the
viscous material
from the guide pipe 4 to.metal tube 6. In addition, this example may be
applied to another
optical fiber cable manufacturing apparatus.
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CA 02400331 2002-08-14
Although controlling the actuation amount of the pump 10 may be performed
manually, an example will be described of configurations for automatically
controlling the
pump 10. For example, the control apparatus of the optical fiber cable
manufacturing
apparatus 1 is provided with the pump actuation control unit 40 (see Fig. 1)
for controlling
the pump 10. In this example, the pump actuation control unit 40 is provided
in advance
with the pump actuation amount Js of steady operation and pump actuation
amount Jp of
start of operation.
The pump actuation amount Js of steady operation is an actuation amount of the
pump 10 when the viscous material is stably supplied from the guide pipe 4
into the metal
tube 6 at the set flow rate Rs. Further, the pump actuation amount Jp of start
of operation is
greater than the pump actuation amount Js of steady operation, and is set as
appropriate
corresponding to various respects such as capability of the pump 10. In this
example,
information of the pump actuation amounts Js and Jp are given to the pump
actuation
control unit 40 as information of the number of rotations of the pump 10.
When detecting a start of manufacturing of optical fiber cable, for example,
based
on operation information of an operation start button by an operator, the pump
actuation
control unit 40 actuates the pump 10 with the pump actuation amount Jp of
start of
operation. Then, according to a program given in advance, the pump actuation
control unit
40 gradually decreases the actuation amount of the pump 10 to the pump
actuation amount
Js of steady operation, and starts actuating the pump 10 with the pump
actuation amount Js
of steady operation at about the time a stable supply of the viscous material
from the guide
pipe 4 into the metal tube 6 is started.
According to this example, since the actuation amount of the pump 10 at the
time of
starting to manufacture optical fiber cables is set to be greater than that of
steady operation,
it is possible to obtain the rise in the pressure of the viscous material
inside the supply pipe
8 faster than the conventional case. In this way, a supply of the viscous
material from the
guide pipe 4 to the metal tube 6 is stabilized faster, and it is thereby
possible to greatly
reduce failures at an earlier stage of manufacturing optical fiber cables
caused by lack or
shortage of the viscous material.
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CA 02400331 2002-08-14
The third example of pressure control is capable of, without providing the
supply
pipe 8 with the first valve 21, pressure sensor apparatus 12 and/or pressure
adjusting
apparatus 34, greatly reducing failures at an earlier stage of manufacturing
optical fiber
cables only by increasing the actuation amount of the pump 10 at the time of
starting to
manufacture optical fiber cables as described above than the steady operation,
and therefore
of having great effectiveness with the conventional configuration kept.
In addition, the present invention is not limited to above embodiments, and
capable
of being carried out in various embodiments. For example, in the first and
second examples
of pressure control, the set pressure Ps is a pressure value of the viscous
material inside the
supply pipe 8 at the time the viscous material is stably supplied from the
guide pipe 4 to the
metal tube 6. However, appropriate values other than the above pressure value
may be used
as a set pressure value.
Further, in the second example of pressure control, the pressure sensor
apparatus 2 is
omitted, but may be provided as in the first example of pressure control. In
this case, it is
possible to open the valve 21 when detecting that the pressure of the viscous
material inside
the viscous material supply pipe 8 is increased by the pre-pressurizing
operation and
stabilized by the pre-pressurizing control unit 30 based on the detection
value of the
pressure sensor apparatus 22.
The guide pipe 8 is provided with a pump and an open/close apparatus of the
pipe at
its portion located downstream of the pump, the pump is actuated with the
open/close
apparatus such as a valve closed before starting to manufacture optical fiber
cables, thereby
performing pre-pressurizing operation on the viscous material to increase the
pressure of
the viscous material inside the viscous material passing portion between the
pump and
open/close apparatus, and the open/close apparatus is opened to start
manufacturing optical
fiber cables. In this way, the pressure of the viscous material inside the
material passing
portion between the pump and open/close apparatus has been increased by the
pre-
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CA 02400331 2002-08-14
pressurizing operation on the viscous material, and then manufacturing of
optical fiber
cable is started. As a result, it is possible to supply the viscous material
from the viscous
material guide pipe into the metal tube at a flow rate nearly equal to the set
flow rate when
starting to manufacturing optical fiber cables.
In this way, it is possible to eliminate almost all of failures at an earlier
stage of
manufacturing optical fiber cables caused by lack or shortage of the viscous
material.
Further, in the invention in which prior to starting to manufacture optical
fiber
cables, the actuation amount of the pump is set to be greater than the pump
actuation
amount of steady operation, it is possible to greatly hasten the rise in the
pressure of the
viscous material in the viscous material guide pipe as compared to the
conventional case. It
is thereby possible to hasten a stable supply of the viscous material from the
viscous
material guide pipe to the metal tube, and to, as in above-mentioned
embodiments,
eliminate almost all of failures at an earlier stage of manufacturing optical
fiber cables
caused by lack or shortage of the viscous material.
Further, in the apparatus provided with a configuration for automatically
controlling
the pump and/or the operation of the open/close apparatus for pre-
pressurizing, for
example, pressing an operation start button enables the apparatus to
automatically operate a
series of operations required for the pre-pressurizing with manual operations
for the pump
and open/close apparatus saved. In this way, without placing burdens on
operators, etc, it
is possible to greatly reduce failures at an earlier time of manufacturing
optical fiber cables.
Industrial availability
The present invention is described to obtain a new apparatus for manufacturing
metal sheathed optical fiber cables, and the same effectiveness is obtained
when applying
the present invention to an apparatus using plastic tapes, instead of metal
tapes, to
manufacture plastic sheathed optical fibers. The present invention is also
applicable to
apparatuses for sheathing various cable materials, instead of optical fibers,
with metal or
plastic to manufacture sheathed cables.
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