JPH09297251A - Optical cable and optical cable manufacturing equipment - Google Patents

Abstract

(57) An optical cable having a small residual elongation strain during manufacturing, a small contraction in the longitudinal direction thereafter, and a small expansion and contraction due to temperature change, and a manufacturing apparatus therefor are provided. A manufacturing apparatus of the present invention includes a wire rod feeding side driving unit, a wire rod winding side driving unit, and a drive control unit, and a margin for a plurality of tension loads and tension adjustment errors occurring in the longitudinal direction of the wire rod in each process. The wire rod in each step is wound on a drum with a tension based on the sum of the above. It is also possible to equip the wire rod intermediate pressing device on both sides of the wire rod area where a large tension is locally applied or on the lower side in the wire rod feeding direction, and to control the tension of the wire rod by the intermediate pusher device drive control unit. The optical cable of the present invention is formed by mixing the plastic material forming the slot rod and / or the cable jacket with fiber-like fibers having a low linear expansion coefficient.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable optical cable in which movement of an optical fiber core is suppressed and a manufacturing apparatus for the same.

A conventional optical cable has a cross-sectional structure as shown in FIG. 1, and a conventional optical cable manufacturing process is shown in FIG.
As shown in. In FIG. 1, the optical cable 1
From the center, tensile strength body 2 (single steel wire, steel stranded wire, etc.),
The slot rod 3, the fiber core wire 5 housed in the slot 4, the press winding 6, the metallic sheath 7, and the cable jacket 8
It is composed of However, although it is shown in FIG. 1 for the sake of convenience that there is a gap between the respective constituent members, the tensile strength member 2, except between the slot 4 and the fiber core wire 5 and between the fiber core wires 5, is The slot rod 3, the press winding 6, the metal sheath 7 and the cable jacket 8 are manufactured so that there is no gap between them. Also, the metal sheath 7
May not be provided. Usually, polyethylene is laminated on the surface of the metal sheath 7, and this is integrated with polyethylene which is a material of the cable jacket 8 during the manufacturing process.

The first manufacturing process of an optical cable is shown in FIG.
As shown in (a), a tensile strength member 2 such as a steel wire is fed from a tensile strength member drum 9, and in the extrusion molding machine 10, the tensile strength member 2 is used as a core to coat polyethylene with a cylindrical shape, and a spiral is applied to the cylindrical surface through a die 11. In this process, extrusion molding is performed so as to provide a plurality of slots (grooves) 4, and the slot rod 3 is sent while being cooled through the water tank 12 and finally wound around the slot rod drum 13. In this case, since the plurality of slots 4 are spirally provided at a certain pitch, the tensile strength body drum 9 and the slot rod drum 13 are synchronously rotated about the slot rod feeding direction, and the driving unit 14 of the tensile strength body drum 9 is used. And drive part of slot rod drum 13
The feed rate with 15 is adjusted. In this step, when the slot 4 is provided, the slot rod 3 is extruded through the die 11 without attaching the slot 4 and the slot rod 3 is placed in a water tank.
The slot 4 may be provided by cutting after cooling through the inside.

In the second manufacturing process, as shown in FIG. 2B, the fiber cores 5 supplied from a plurality of bobbins 18 are accommodated in each slot 4 (in the figure, 5 tapes are accommodated in each of the four slots). ), While holding the fiber core wire 5 in the slot 4, a press winding 6 (such as a waterproof tape or a non-woven fabric) is applied to the outer periphery of the slot rod 3, and finally the press-wound slot rod 22 is pressed and wound. It is a process of winding around 19. In this case, the slots 4 are provided spirally at a certain pitch, and the bobbins 18 to the slots 4 are provided.
The slot rod drum 13 and the press-winding drum 19 are synchronously rotated about the slot rod feed direction as an axis so that the position where the fiber core wire 5 is supplied can be fixed, and the drive portion 20 of the slot rod drum 13 and the press-winding drum are pressed. drum
The feed speed of the drive unit 21 of 19 is adjusted.

In the third manufacturing process, as shown in FIG. 2 (c), the press-wound slot rod 22 is sent out from the press-winding drum 19, and the slot rod 22 wound by the press-winding is used as a core for extrusion molding. The polyethylene is extruded into a cylindrical shape by the machine 23 to form the cable jacket 8,
In this step, the cable 1 having the cable jacket 8 formed is sent through the water tank 12 while being cooled, and finally the cable 1 is wound around the cable drum 24. In this case, the feed rates of the drive unit 25 of the press winding drum 19 and the drive unit 26 of the cable drum 24 are adjusted. Note that FIG. 2C shows the case where the metal sheath 7 is inserted.

In the above three manufacturing steps, the three wire members of the cable 1, namely the tensile strength member 2, the slot rod 3,
Further, the slot rod 22 wound by pressing is guided by the guide component 27 provided on the manufacturing line. 3 (a) and 3 (b) are views showing two examples of the slots provided in the first manufacturing process. FIG. 3 (a) is S-shaped (helix direction is constant), and FIG. 3 (b) is The SZ type (the spiral direction is alternately changed at every half pitch) is shown.

[0007]

When the conventional optical cable as described above is used in a cold region (it drops to about -30 ° C for an overhead cable and about -10 ° C for an underground cable), a closure (a connection box) attached to a cable connection portion is used. ) Or joint (underground connection housing), the fiber core wire 5 is the cable 1
A phenomenon may occur in which the inside of the body sticks out inside the closure or inside the joint.

For example, the slot rod 3 shown in FIG. 1 is provided with five slots 4 and five fiber core wires 5 are accommodated in each slot (4 core tape). The five (4 core tape) fiber core wires 5 do not necessarily protrude all together,
In some cases, only one of the four (four-core tape) fiber core wires 5 may be projected. Also, this phenomenon is not always observed in all slots at the same time. Further, such a phenomenon does not always occur at both ends of one cable. As such, the occurrence of this phenomenon is extremely irregular. This phenomenon occurs in both overhead and underground cables, even in places where the wind is not strong.

When the fiber core wire 5 projects from the inside of the cable 1 to the inside of the closure or joint, the fiber core wire 5 remains in the protruding state, and bending deformation occurs in the fiber core wire 5, causing bending loss. There is a problem that becomes.

In addition, a twist may occur between the cable jacket and the slot rod at the connecting portion such as the closure. Due to such a twist, outside the cable (ie,
The protruding fiber core wire may be twisted with respect to the core wire that was originally wired inside the closure or the like, or the protruding fiber core wire may interfere with internal parts such as the closure. There is a problem.

In addition, the conventional optical cable as described above is used in a warm area (70 ° C. for an overhead cable, 30% for an underground cable).
If it is used at a temperature up to about 0 ° C.), a phenomenon may occur in which the inner fiber core wire 5 such as a closure is pulled into the cable 1. In this case, even if the fiber core wire 5 is accommodated while maintaining a sufficient radius when the cable is connected, there is a problem that the bending radius becomes small due to this phenomenon.

Further, in the conventional manufacturing process as described above, a driving unit is usually provided in each of the drums of the tensile strength member, the slot rod, the slot rod wound under pressure, and the cable. In order to adjust the slot pitch of the slot rod, in the slot rod extrusion forming step and the press winding step among the above-mentioned three steps, the rotation speed of the drum and the wire rod feeding speed around the wire rod feeding direction are adjusted.

On the other hand, in the cable jacketing step, the wire feeding speed is only adjusted without rotating the drum about the wire feeding direction. However, when adjusting the wire rod feed rate in the above-mentioned three manufacturing processes, excessive tension is applied to the slot rod, the slot rod that is pressed and wound, and the plastic material of the cable. In this way, a relatively large tension is repeatedly applied to the plastic material during the above three steps. That is, before the residual elongation strain of the plastic material generated in the previous step is eliminated, the elongation strain generated in the next step is added, and the residual elongation strain is accumulated in each step. For this reason, there is a problem that a large residual elongation strain is generated in the slot rod made of polyethylene, the cable jacket, etc. at the time of manufacturing the cable.

When the slot rod is provided with a plurality of slots by cutting, a large cutting resistance is generated in the slot rod extrusion molding process, and a large elongation strain is generated in the range from the slot cutting portion of the slot rod to the slot rod drum. I am letting you.

Such residual elongation strain at the time of manufacturing is naturally released later and causes deformation of the wire rod. When the wire rod is deformed as described above, the fiber core wire is slightly bent. Occurs, which in turn causes bending loss, which deteriorates the transmission characteristics.

Therefore, an object of the present invention is to provide an optical cable and its manufacturing apparatus in which the residual elongation strain at the time of manufacturing is reduced, thereby reducing the subsequent shrinkage in the longitudinal direction and further reducing the expansion and contraction due to temperature change. It is in.

[0017]

In order to achieve the above object, an optical cable manufacturing apparatus of the present invention is provided with a wire rod feeding side driving unit, a wire rod winding side driving unit, and a wire rod feeding side driving unit and a wire rod winding side. A drive control unit that controls the tension of the wire rod with the drive unit is provided, and the tension is based on the sum of margins for multiple tension loads and tension adjustment errors that occur in the longitudinal direction of the wire rod in each process. It is characterized by winding up on a drum.

Further, the optical cable manufacturing apparatus of the present invention comprises wire rod pressers on both sides of the wire rod range where a large amount of local tension is applied or on the lower side in the wire rod feed direction, and the wire rod pressers arranged on both sides of the wire rod range. Between the driving units of the wire rod or between the wire rod feeding side driving unit and the driving unit of the wire rod intermediate pushing device arranged on the lower side in the wire rod feeding direction, an intermediate pushing device drive control unit for controlling the tension of the wire rod is provided. Can be equipped.

Furthermore, the optical cable of the present invention is characterized in that the plastic material forming the slot rod and / or the cable jacket is formed by mixing fiber fibers having a low linear expansion coefficient.

According to the present invention as described above, in the cable manufacturing process, the tension applied to the slot rod or the cable jacket made of a plastic material such as polyethylene is controlled so as to have a minimum required value. It is possible to reduce the residual elongation strain at the time of manufacturing and reduce the shrinkage that occurs in the slot rod or the cable jacket that is subjected to a heat cycle after manufacturing. Further, by providing the wire rod pushing device, it is possible to locally limit the wire rod range to which a large tension is applied. In addition, by mixing fiber-shaped fibers into a plastic material such as polyethylene that constitutes the slot rod and / or the cable jacket, expansion and contraction due to temperature change and strain at the time of applying tension are reduced, so that heat cycle occurs. It is possible to suppress both the contraction of the slot rod and the cable jacket and the expansion and contraction of the both that occur due to temperature change.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION First, the mechanism by which a fiber core moves in a cable and is projected or retracted at a cable connecting portion is clarified. Hereinafter, consider an optical cable in which the fiber core is tightly housed so that there is basically no slack in the slot. However, in reality, since the fiber core wire has a slight slack with respect to the slot length of the slot rod, there is a bend in the fiber core wire in the slot. When there is a bend in the fiber core in the cable, the fiber core is constantly subjected to a straightening force until the fiber core shifts to a stable stress state. That is, the fiber core wire moves toward a portion where the bending (radius of curvature) is large (a portion where the stress is small) or toward a stress releasing portion such as a cable connecting portion. Here, the stress releasing portion means a portion in which the fiber core wire housed in the slot of the slot rod is in a stress releasing state, and is a portion that is inside the cable by about 10 to 30 m from the cable cutting portion of the cable connecting portion. Is.

First, considering the case where the cable being laid crosses vibrates laterally, an inertial force acts on the fiber core wire in the cable, and this inertial force acts between the electric poles laid across the cable. It acts toward the central portion of the cable and acts to draw the fiber core wire from the cable connecting portion into the inside of the cable. This is because the cable running over the utility pole bends downward and becomes a parabolic shape. However, since the bending angle of the cable is small and the mass of the fiber core wire is small, the force toward the central portion of the cable is small.

From the above, the influence of the inertial force acting on the fiber core wire (in the cable longitudinal direction) with the lateral vibration of the cable on the movement of the core wire is small. However, due to the lateral vibration of the cable, the frictional force acting on the fiber core wire changes from static friction to dynamic friction, and the constraint on the fiber core wire (due to the frictional force) is weakened. , The power to get straight)
In the presence of, the fiber core wire is likely to move.
By the way, the protrusion of the core wire is also observed in an underground cable that is not subjected to lateral vibration of the cable. Therefore, in the following consideration of the core wire protrusion, the core wire protrusion phenomenon based on the temperature change of the cable will be considered.

Since the slot rod and the cable jacket are pulled several times during the cable manufacturing process, a residual elongation strain (history during cable manufacturing) occurs in them. So when a cable goes through a heat cycle,
The initial lengths of the slot rod 3 and the cable jacket 8 are not maintained and gradually become shorter (hereinafter, this is referred to as residual elongation strain elimination shrinkage). In order to confirm the residual elongation strain elimination shrinkage of the slot rod in the laboratory, and to clarify the change of the length with respect to the initial fiber core wire, put the slot rod having a steel wire (tensile strength body) in the core, Temperature -40
The temperature was changed from ℃ to +80 ℃ and examined in the acceleration experiment. The results of this experiment are shown in FIGS. In these figures, Δl represents the amount of contraction of the slot rod.

The conditions relating to the samples used in the experiment (experimental sample conditions) are as follows, and were stored at room temperature. (1) S type slot rod: S type slot pitch 500mm
/ 360 degree, slot rod sample length 500 ~ 600m
m, number of slots 5, outer diameter 14.6 mm (equivalent outer diameter 12 mm excluding the cross-sectional area for 5 slots), steel wire outer diameter 2.6 mm (2) SZ type slot rod: SZ type slot pitch 50
0mm / 290 degree, slot rod sample length 500-60
0 mm, number of slots 5, outer diameter 17.3 mm (equivalent outer diameter 14.9 mm excluding the cross-sectional area for 5 slots), stranded wire outer diameter 1.2
mm x 7

FIG. 4 uses a dozen S-type slot rods, and FIG. 5 uses three SZ-type slot rods. These samples are placed in a constant temperature bath and heat cycled from -40 ° C to + 80 ° C. Is a diagram showing an outline of expansion and contraction history of the slot rod when about 10 cycles are given, and both are represented by an average value of data obtained from a plurality of slot rods. FIG. 6 shows an S-shaped slot rod of the same manufacturing lot (same size and same shape) as the sample of FIG.
It is the figure which showed the outline of the expansion-contraction history of the slot rod when a heat cycle was given up to ° C, and is represented by the average value of the data obtained from a plurality of slot rods.

The thin lines in the graphs of FIGS. 4 and 5 show the characteristics during the heat cycle, and the thick lines show the characteristics when they are almost saturated. However, the heat cycle is −40 ° C., + 20 ° C., + 80 ° C. in FIGS. 4 and 5, and 0 ° C., +2 in FIG.
Each temperature of 0 ° C. and + 70 ° C. was held for 1 hour or more, and the change time between each temperature was about 30 minutes. In this experiment, when the temperature of the slot rod changes, it expands and contracts in the longitudinal direction according to the linear expansion coefficient of the material shown in FIG. 7, for example. At the same time, as the heat cycle of about 10 cycles is repeated, the slot rod remains contracted with respect to the initial length, and the contraction amount of the slot rod gradually increases until the contraction is saturated. Come on. Saturation of shrinkage occurs because the residual elongation strain of the slot rod during cable manufacturing has been eliminated.

From FIG. 4, it can be seen that the temperature expansion / contraction at the end of the heat cycle of the S-shaped slot rod is about 5 mm when the temperature difference is 120 ° C. and the slot rod is converted into 1 m. When the temperature expansion and contraction of a slot rod alone without a steel wire in the center is calculated using the above experimental sample conditions (1) and FIG. 7, a temperature difference of 120 ° C. results in about 20 per 1 m of the slot rod.
mm. Therefore, it is understood that the expansion and contraction of the slot rod is restricted by the friction with the steel wire. By increasing the surface area of the strength member, the constraint due to the frictional force between the strength member and the slot rod can be increased, and the contraction speed for eliminating residual elongation strain of the slot rod can be slowed.

Regarding the residual elongation strain eliminating shrinkage at the end of the heat cycle, when the slot rod length was evaluated at 20 ° C., it was found that the residual elongation strain eliminating shrinkage of about 3 mm in terms of 1 m of the slot rod occurred. . The residual elongation strain relief shrinkage per 35 m, which is the normal cable span, is 105 mm calculated using the results obtained from slot rod samples of length 500-600 mm (ignoring dimensional effects). This value is a value close to the actually observed amount of the fiber core wire protrusion.

From FIG. 5, it can be seen that the temperature expansion / contraction of the SZ type slot rod at the end of the heat cycle is about 5 mm when the temperature difference is 120 ° C. and the slot rod is converted into 1 m. Now, comparing with the calculated temperature expansion / contraction of the slot rod without the steel stranded wire at the center, the expansion / contraction of the SZ type slot rod is restricted by the friction with the steel stranded wire as in the case of the S type slot rod cable. I understand that. Regarding the residual elongation strain eliminating shrinkage at the end of the heat cycle, when the slot rod length was evaluated at 20 ° C., it was found that the residual elongation strain eliminating shrinkage of about 4 mm in 1 m slot rod conversion value occurred.

Further, according to FIG. 6, the temperature expansion / contraction of the slot rod at the end of the heat cycle is about 1 mm when the temperature difference is 70 ° C. and the slot rod is converted into 1 m. Further, it can be seen that the residual elongation strain elimination shrinkage at the end of the heat cycle is very small.

Next, FIG. 4 and FIG. 6 showing the results of the experiment using the S-type slot rod of the same manufacturing lot (same size and shape).
Comparing with, the expansion and contraction amount of the slot rod per constant temperature difference is smaller in the case of the high temperature side heat cycle temperature condition of FIG. 6 than in the case of the low temperature side heat cycle temperature condition. The reason for this is that, as shown in FIG. 8 (shear modulus of polyethylene measured at a frequency of 1 Hz), the modulus of elasticity of polyethylene is, for example, 70 kg / cm ² , +20 at −40 ° C.
20 kg / cm ² at ℃, 1 kg / cm ² at +80 ℃, etc. It becomes smaller as the temperature gets higher, so the effective expansion and contraction force of the slot rod on the high temperature side is small, so it is restrained by friction between the slot rod and the steel wire. This is because it is difficult to counter.

Further, the speed at which the residual elongation strain is eliminated and contracted also becomes smaller under the heat cycle temperature condition on the high temperature side of FIG. 6 as the effective expansion / contraction force of the slot rod becomes smaller. However, if the slot rod continues to be subjected to a heat cycle for a long period of time, it should gradually shrink so as to eliminate the history (residual elongation strain) at the time of manufacturing the cable.

Next, the relationship between expansion and contraction of the slot rod and movement of the core wire will be shown. First, (1) When the ambient temperature changes on the low temperature side (for example, from + 20 ° C to -40 ° C in Fig. 4), the slot rod contracts according to the linear expansion coefficient of the material, and in addition to this, the low temperature side So polyethylene has a large elastic modulus,
Since the effective expansion and contraction force of the slot rod increases, the slot rod surely contracts, and the residual elongation strain at the time of manufacturing the cable is eliminated at once. in this way,
The residual elongation strain relief contraction acts to enhance the contraction of the slot rod when the temperature decreases. This residual elongation strain-resolved shrinkage remains in a contracted state. As a result, the length of the slot provided spirally on the slot rod is shorter than the length of the fiber core wire whose linear expansion coefficient is smaller by one digit or more than that of the slot rod (polyethylene). Therefore, the length of the fiber core wire in the cable is relatively longer than the length of the slot.

At this time, when the fiber core wire shrinks together with the slot rod, the bending of the fiber core wire in the slot of the slot rod increases, and the fiber core wire is transformed into a fiber core wire according to the high Young's modulus of about 7300 kg / mm ^{2 of} the fiber. The bending force increases the restoring force that tends to be straightened. For this reason, the fiber core wire in the slot acts as a stress relieving portion against the frictional force acting between the slot and the fiber core wire, between the fiber core wires, and between the fiber core wire and the press winding. A force is applied to move toward or toward a fiber core portion (a portion where stress is small) having a large bending radius in the slot.

On the other hand, (2) the ambient temperature is on the high temperature side (see, for example, FIG.
When changing from + 20 ° C. to + 80 ° C.), the slot rod expands according to the linear expansion coefficient of the material, and if there is residual elongation strain in the slot rod, residual elongation strain is eliminated and contracted. However, this residual elongation strain elimination contraction acts to cancel the elongation according to the linear expansion coefficient of the slot rod, but at the high temperature side of the heat cycle, the elastic modulus of polyethylene is small and the effective expansion and contraction force of the slot rod is small. Therefore, this canceling force is small. As a result, the elongation of the slot rod with the increase of the ambient temperature becomes larger than the elongation of the fiber core wire having a small linear expansion coefficient.

At this time, if the core wire inside the optical cable is accommodated in the slot in a substantially tight manner, the fiber core wire outside the cable is drawn into the cable. However, the pull-in phenomenon does not occur if the fiber core wire in the cable has a large amount of slack or a large amount of residual elongation strain elimination shrinkage.

As described above, the main causes of the movement of the fiber core wire in the cable and the protrusion and withdrawal are as follows.
It can be seen that the original slot rod (or slot) length or cable length varies with the length of the fiber core.

The S-shaped slot rod is provided with a plurality of S-shaped (spiral) slots, that is, it is as if a plurality of linear polyethylene is spirally wound around the steel wire. Therefore, the slot rod is twisted around its axis when the temperature is expanded and contracted. FIG.
About S type slot rod, -40
FIG. 7 is a graph showing the rotation angle around the axis of the end surface of the slot rod when a heat cycle from 0 ° C. to + 80 ° C. is applied, and is a diagram showing an average value of data obtained from ten or more samples. According to this figure, the S-shaped slot rod has a temperature difference of 1
It can be seen that in the case of 20 ° C., about ± 5 ° is rotated about the angle of 20 ° C. per 1 m. When converted to a normal cable span of 35 m, it will rotate about ± 175 °.

As in the case of the temperature expansion and contraction of the slot rod, the slot rod is restrained by the frictional force with the steel wire (tensile member). It should be smaller than the rotation angle without. Also,
Regarding residual shrinkage strain elimination shrinkage, if strictly measured,
The amount of rotation of the slot rod generated in response to the residual elongation strain eliminating shrinkage should not be recovered by the amount that the slot rod undergoes residual elongation strain eliminating shrinkage in the longitudinal direction (a little less than 3 mm / m at 20 ° C).

Now, using the parameters of the above experimental sample conditions, it is estimated from the calculation result of the change in the slot length of the slot rod that occurs when the S-shaped slot rod makes one rotation (360 ° rotation). It is as small as about 4 mm per 35 m of cable span, and it can be seen that there is almost no effect on the protrusion or retraction of the fiber core wire.

On the other hand, the rotation of the SZ type slot rod due to the temperature expansion and contraction is almost 0 ° during the temperature fluctuation. This is because, as shown in FIG. 3 (b), the slots of the SZ type slot rod are alternately provided so that the spiral winding directions are reversed every half pitch (250 mm) thereof. This is because they act so as to cancel out the rotations of the rods.

The cable jacket also undergoes temperature expansion / contraction and residual elongation / strain elimination contraction in the same manner as the slot rod. The expansion and contraction of the cable jacket due to temperature and the contraction to eliminate the residual elongation distortion are synchronized with the expansion and contraction of the temperature of the slot rod and the contraction to eliminate the residual elongation distortion through the press winding. Therefore, the cable jacket acts to expand at least the expansion / contraction movement of the slot rod or the residual elongation / strain relief contraction. When the rotation of the slot rod described above is transmitted to the cable jacket, the cable jacket is twisted around its axis.

Next, the reason why the protrusion or the retraction of the fiber core wire occurs irregularly will be considered. In FIG.
The fiber core wire 5 is in a state of being elastically deformed due to a bend having a certain radius of curvature in the cable longitudinal direction in accordance with the amount of slack at the time of manufacturing the cable. , And is held in the slot 4 by a temporary balance of a force such as a frictional force with the press winding 6. At this time, the frictional force acting on each fiber core wire 5 is not necessarily uniform. That is, for example, one slot rod 3 is engraved with five slots 4, and a fiber core wire 5 is provided for each slot (4 core tape).
5 pieces are stored, but the amount of slack in each fiber core (the amount of restoring force that tends to straighten according to the bending radius of the fiber core) or the mechanical state in which the frictional force is acting is , Each fiber core is different. Therefore, the five (4 core tape) fiber core wires 5 in each slot 4 do not always protrude at the same time.

Further, in the cold district, when there is a connecting portion at both ends of one cable, the fiber core wire may protrude at one end and the core wire may not move at the other end. This is because the friction (restraint) between the slot rod and the steel wire is not uniform in the manufacturing process, or a part of the cable is installed by bending it with an underground cable, etc. As a result, the starting point of expansion and contraction of the slot rod is not always located at the center of the length of one cable.

As described above, since the force acting on each fiber core or the force acting on the slot rod is not uniform in the cable longitudinal direction, the same phenomenon does not always occur at both ends of the cable.

Next, an embodiment of the cable manufacturing apparatus of the present invention will be described with reference to the drawings. FIG. 10 is a diagram showing this first embodiment. The cable manufacturing process is roughly divided into three processes: a slot rod extrusion molding process, a press winding process, and a cable outer covering process. FIG. 10A is a diagram illustrating a slot rod extrusion molding process. Tension T required for winding the finished slot rod 3
1 is a load generated in the longitudinal direction of the slot rod,
Load when the tensile strength body 2 is sent out from the tensile strength body drum 9,
The load for passing the slot rod extrusion molding portion 10, the load for forming the slot 4 in the slot rod 3 with the die 11, the guide member 27 for guiding the tensile strength body 2 or the slot rod 3 to a predetermined position on the manufacturing line, etc. Load due to the frictional force, the load at the time of winding on the slot rod drum 13, and the tension composed of the sum of the margins for the tension adjustment error. In practice, the optimum value can be determined by moving the manufacturing line using the calculated tension T1 as a guide and adding a minimum necessary margin to the limit tension at which slackening of the wire starts.

A drive controller 28 is used between the tensile strength member feed unit 9 and the slot rod winding unit 13, that is, between the wire rod feeding side driving unit 14 and the winding side driving unit 15 to drive both driving units. 1
By controlling the speed and torque of 4 and 15, the tension of the wire rod (that is, the slot rod) is controlled. in this case,
By controlling the torque to the tension T1 based on a plurality of loads generated in the longitudinal direction of the wire and the sum of the margins for the tension adjustment error, only the minimum required tension is applied to the wire, so The tension for the margin against the adjustment error or the like only causes a slight residual elongation strain in the slot rod 3. As described above, the occurrence of extension strain of the slot rod 3 from the water tank 12 to the slot rod winding portion 13 can be suppressed.

FIG. 10 (b) is a diagram for explaining the press winding step. The tension T2 required when winding the finished press-wound slot rod is a load generated in the longitudinal direction of the press-wound slot rod, and when the slot rod 3 is sent out from the slot rod drum 13. Load, load generated when the fiber core wire 5 is inserted into the slot 4 of the slot rod, frictional force in the guide part 27 or the like that guides the slot rod 3 or the slot rod 22 that has been wound to a predetermined position in the manufacturing line Load, the load when winding on the press winding drum 19,
And the tension consisting of the sum of the margins for the tension adjustment error. In practice, the optimum value can be determined by moving the manufacturing line using the calculated tension T2 as a guide and adding a minimum necessary margin to the limit tension at which the wire rod starts to loosen.

A drive control unit 28 is provided between the slot rod feeding unit 13 and the press-wound slot rod winding unit 19, that is, between the wire rod feeding side driving unit 20 and the winding side driving unit 21. Is used to control the speeds and torques of both drive units 20 and 21, thereby controlling the tension of the wire rod (that is, the slot rod 3 and the slot rod 22 that is pressed and wound). In this case, by controlling the torque to a tension T2 based on a plurality of loads generated in the longitudinal direction of the wire and a sum of margins for tension adjustment errors, only the minimum necessary tension is applied to the wire. At most, the tension corresponding to the margin for the tension adjustment error causes only a slight residual elongation strain in the slot rod. As mentioned above,
It is possible to suppress the occurrence of extension strain of the slot rod from the slot rod feeding portion to the slot rod winding portion 19 which is pressed and wound.

FIG. 10C is a view for explaining the cable outer covering process. The tension T3 required for winding the finished cable is a load generated in the longitudinal direction of the cable, and is a load for sending out the slot rod 22 with the press winding, and a metal such as a stainless sheath on the press winding 6. The load generated when the sheath 7 is covered, the load when the outer cover is formed by the extrusion molding machine 23, the slot rod 22 which is pressed and wound, the slot rod which is covered with the metal sheath 7 and the completed cable 1 Load due to frictional force in the guide part 27, etc. that guides to a predetermined position,
It is determined from the load when the cable is wound around the cable drum 24 and the tension that is the sum of the margins for the tension adjustment error. In practice, the optimum value can be determined by moving the manufacturing line using the calculated tension T3 as a guide and adding a minimum necessary margin to the limit tension at which slackening of the wire starts.

The drive control unit is provided between the slot rod feed unit 19 and the cable take-up unit 24, which are pressed and wound, that is, between the wire rod feed side drive unit 25 and the take-up side drive unit 26.
By controlling the speed and torque of both drive units 25 and 26 using 28, the tension of the wire rod (that is, the cable 1 etc.) is controlled. In this case, by controlling the torque to the tension T3 based on a plurality of tensions generated in the longitudinal direction of the wire and the sum of the margins for the tension adjustment error, only the minimum necessary tension is applied to the wire, At most, the tension corresponding to the margin for the tension adjustment error causes only a slight residual elongation strain in the slot rod. As mentioned above,
It is possible to suppress the occurrence of elongation strain of the slot rod or the cable from the slot rod feeding portion that has been press-wound to the cable winding portion.

FIG. 11 is a diagram showing a second embodiment of the present invention. The cable manufacturing apparatus of this embodiment includes a wire rod pressing device in the step of cutting a slot rod to form a plurality of slots. That is, after the slot rod 3 to which polyethylene is attached by extrusion molding using the tensile strength member 2 as a core passes through the cooling water tank 12, the slot rod 3 is cut by the cutting tool 29 to form a plurality of slots 4. In this way, when the slot rod 3 is cut by the cutting tool 29 to form the plurality of slots 4, a large cutting resistance is generated and a large tension is applied to the slot rod 3.

Therefore, in this embodiment, the wire rod pressing device 30 is provided on both front and rear sides in the range where a large tension is applied to the slot rod or on the lower side in the slot rod feeding direction,
Between the drive units 31 and 32 of the wire rod intermediate pushing device arranged on both sides, or between the wire rod feeding side drive unit 14 and the medium pushing device drive unit 32 (on the lower side in the wire rod feeding direction) arranged on one side. A wire rod centering device drive control unit 33 for controlling the tension of the wire rod is provided.

In this case, if the tension of the wire 3 is controlled in a range where a large tension is applied, the tension is adjusted to the cutting resistance load only in this range, and the residual elongation strain of polyethylene is effectively suppressed. You can That is, the range in which a large tension is applied can be locally limited only to the slot cutting portion of the slot rod. By doing so, it is possible to significantly reduce the influence of the cutting resistance load in the wire feed direction on the wire 3 ′ on the lower side of the slot cutting portion, and it is possible to suppress the occurrence of residual elongation strain of the polyethylene molded material. In this case, in order to compensate for the reduction of tension in each manufacturing process and ensure the guide of the wire rod on the manufacturing line, the guide component 27
It is preferable to increase the number of

FIG. 12 is a diagram showing a third embodiment of the present invention. In this embodiment, the linear expansion coefficient of, for example, glass fiber, carbon fiber, etc. in the slot rod of the cable and / or in the cable jacket or polyethylene resin is 10
^The fibrous fiber 34 having a small value of about ⁻⁶ / ° C. is mixed. As a result, the coefficient of linear expansion of the slot rod and the cable jacket can be reduced by about one digit, and both the shrinkage of the slot rod and the cable jacket made of polyethylene due to elimination of residual elongation strain and the expansion and contraction due to temperature change are suppressed. You can

As described above, when the expansion and contraction of the slot rod is suppressed, the twisting of the slot rod is also suppressed accordingly. In the case of the S-type slot rod, due to the helical structure of the slot, temperature expansion and contraction and residual elongation strain relief contraction cause twisting in the slot rod during expansion and contraction. These problems can be solved. Also, by attaching a protrusion to the tensile member, expansion and contraction of the slot rod and S
Although the twist of the die slot rod can be suppressed to some extent, its effect is small as compared with the case where the fibrous fibers 34 are mixed.

In the above description, it is assumed that polyethylene is used as the material for the slot rod and the cable jacket, but it is needless to say that the material is not limited to polyethylene in the present invention, and a suitable material is used. You can In addition, although the cable manufacturing process has been described as being divided into three, for example, the process of extruding a slot rod and the pressing winding process may be connected in series to the same manufacturing line, and the cable manufacturing process is not necessarily three. There is no need to divide.

By the way, in particular, when a cable in which a cable and its suspension line are fixed is crossed over, or when an underground cable is laid, a large tension may be applied to the cable jacket or the slot rod. In such a case, residual elongation strain is generated in them, and therefore, just like the residual elongation strain at the time of manufacturing the cable, there is a problem that the residual elongation strain of the plastic is contracted by the residual elongation strain eliminating shrinkage phenomenon. Therefore, for overhead cables, separate the cables and their suspension lines from each other.
For underground cables, it is necessary to lay them using a cable pusher to prevent such excessive tension from being applied to the cables.

[0060]

As described above, according to the optical cable of the present invention, the residual elongation strain of the cable jacket and the slot rod, which occurs during the cable manufacturing, is significantly reduced. In addition, the shrinkage in the longitudinal direction due to the elimination of the residual elongation strain at the time of manufacturing the cable can be significantly reduced. Further, by providing the wire rod pressing device, it is possible to locally limit the range where a large tension is applied to the wire rod of the manufacturing line. Also,
By mixing fiber-shaped fibers having a small linear expansion coefficient into the plastic, it is possible to suppress both the temperature expansion and contraction of the slot rod and the cable jacket and the contraction due to elimination of residual elongation strain during cable manufacturing. Therefore, when the temperature of the cable changes, the relative movement of the fiber core wire with respect to the slot rod or the cable in the longitudinal direction of the cable can be reduced, and at the same time, the rotation of the S-shaped slot rod can be suppressed.

As described above, the phenomenon that the fiber core wire projects out of the cable and the phenomenon that the fiber core wire is pulled inside the cable can be greatly alleviated. As a result, the bending loss of the fiber core increases due to the protrusion phenomenon of the fiber core, and the contact between the fiber core and the fixed component in the closure or the joint due to the rotation and expansion and contraction of the slot rod and the cable. The increase in bending loss of the core wire is eliminated, and the transmission characteristics of the optical cable are not deteriorated for a long time. Further, since the frequency of failure of the optical cable is reduced, there is an advantage that the cable maintenance cost is reduced.

As an application field of the optical cable and the optical cable manufacturing apparatus of the present invention, it is particularly effective when applied to an optical cable used in a cold region where shrinkage due to elimination of elongation strain remaining in the plastic during manufacturing poses a problem. Furthermore,
If it is used in optical cables for optical subscriber lines that will be developed in the future, it will be effective in achieving long-term high reliability of optical lines.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic sectional structure of a conventional optical cable.

FIG. 2 is a diagram illustrating a manufacturing process of a conventional optical cable.

FIG. 3 is a diagram illustrating a mold of a conventional slot rod.

FIG. 4 is a diagram showing how the S-type slot rod expands and contracts in a low temperature side heat cycle experiment.

FIG. 5 is a diagram showing how the SZ type slot rod expands and contracts in a low temperature side heat cycle experiment.

FIG. 6 is a diagram showing how the S-shaped slot rod expands and contracts in a high temperature side heat cycle experiment.

FIG. 7 is a diagram showing an example of a linear expansion coefficient of polyethylene.

FIG. 8 is a diagram showing an example of shear modulus of polyethylene.

FIG. 9 is a diagram showing a twisted state of an S-shaped slot rod in a heat cycle experiment.

FIG. 10 is a diagram illustrating a manufacturing process of the optical cable manufacturing apparatus according to the first embodiment of the present invention.

FIG. 11 is a diagram illustrating a manufacturing process according to the second embodiment of the optical cable manufacturing apparatus of the present invention.

FIG. 12 is a diagram illustrating the structure of the optical cable of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical cable 2 Tensile body 3 Slot rod 4 Slot 5 Fiber core wire 6 Holding winding 7 Metal sheath 8 Cable sheath 9 Tensile body drum 10 Extrusion molding machine 11 Dice 12 Water tank 13 Slot rod drum 14 Driving portion of the tense body drum 9 15 Drive part of slot rod drum 13 Core wire bobbin 19 Presser winding drum 20 Drive part of slot rod drum 13 Drive part of press winding drum 19 Pressed slot rod 23 Extrusion machine 24 Cable drum 25 Press winding drum 19 Drive part of cable 26 Drive part of cable drum 27 Guide part 28 Drive control part 29 Cutting tool 30 Middle push device 31, 32 Drive part of wire rod middle press device 33 Middle push device drive control part 34 Fiber-shaped fiber

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Kajima 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Within Nippon Telegraph and Telephone Corporation (72) Inventor Yu Nozawa 3-19-3 Nishishinjuku, Shinjuku-ku, Tokyo No. 2 within Nippon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A wire rod feeding side driving unit, a wire rod winding side driving unit, and a drive control unit for controlling the tension of the wire rod between the wire rod feeding side driving unit and the wire rod winding side driving unit. An optical cable manufacturing apparatus, wherein the wire rod in each step is wound on a drum with a tension based on a plurality of tension loads generated in the longitudinal direction of the wire rod and a sum of margins for tension adjustment errors. 2. A wire rod pressing device is provided on both sides of a wire rod region where a large tension is locally applied or on the lower side in the wire rod feed direction, and between the drive parts of the wire rod pushing device arranged on both sides of the wire rod region. Alternatively, an intermediate pusher drive control unit for controlling the tension of the wire rod is provided between the wire rod feeding side drive unit and the drive unit of the wire rod intermediate pushing device arranged on the lower side in the wire rod feeding direction. Item 1. The optical cable manufacturing apparatus according to Item 1. 3. An optical cable, wherein a plastic material forming a slot rod and / or a cable jacket is formed by mixing fiber-like fibers having a low linear expansion coefficient.