JP5455066B2 - Manufacturing method of optical fiber storage spacer - Google Patents

Description

  The present invention relates to a method for manufacturing an optical fiber storage spacer. More specifically, the present invention relates to a method of manufacturing an optical fiber storage spacer in which a spiral groove for rotating an optical fiber in a fixed direction or a groove that alternately alternates in an SZ shape is provided on the outer peripheral surface.

  An optical fiber housing spacer used for an optical fiber cable has a plurality of grooves (slots) extending in the length direction and having a square or U-shaped cross section on the outer peripheral surface thereof. 12A is a perspective view showing an optical cable housing spacer having an SZ-shaped groove, and FIG. 12B is a cross-sectional view thereof. For example, an optical fiber storage spacer 100 shown in FIGS. 12A and 12B is made of heat such as polyethylene around a tension member 101 made of a steel wire, glass fiber reinforced plastic, aramid fiber reinforced plastic, or the like. The spacer main body 102 made of a plastic resin is provided.

  In addition, an SZ-shaped groove 103 is formed on the surface of the spacer body 102, and a tape core or the like in which a plurality of optical fiber cores are arranged in parallel is accommodated in the groove 103, for example. A spacer having such an SZ-shaped or spiral groove can store the optical fiber core wire with high density. And the spacer after optical fiber core wire accommodation is coat | covered with polyethylene resin etc., and turns into an optical fiber cable.

  On the other hand, as a method of manufacturing the optical fiber housing spacer as shown in FIG. 12, for example, the outer periphery of the tensile body 101 is coated with a thermoplastic resin to form a core, and then a die is placed around the core. There is a method of forming a spiral or SZ-shaped groove 103 by extruding a thermoplastic resin while rotating. Conventionally, a method for manufacturing a synthetic resin rod-shaped object serving as the center of an optical fiber storage spacer with high accuracy has also been proposed (see, for example, Patent Documents 1 and 2).

  For example, in the manufacturing method described in Patent Document 2, when manufacturing a resin rod-shaped object having a circular cross-section, the outer diameter of the product is measured, and the value is not once within the set value range. The amount of resin discharged is feedback controlled by adjusting the screw speed of the extruder. Such feedback control is also performed in fields other than resin molding such as metal processing (see, for example, Patent Document 3).

  For example, in the outer diameter measuring apparatus described in Patent Document 3, the outer diameter of a round steel bar having a substantially circular cross section is measured using laser light, and based on the result, immediately before the measuring unit. The operating condition of the installed straightening roll is controlled. Further, in Patent Document 3, the ratio (Tr / Ts) of the time pitch Ts for measuring the outer diameter to the time Tr required for one round of the round bar to be 10 to 100, or the frequency of measuring the outer diameter is disclosed. Is set to 400 to 3000 times / second.

JP-A-5-4272 JP 2002-283440 A Japanese Patent Laying-Open No. 2005-062117

  However, the conventional optical fiber storage spacer has a problem that transmission performance in the longitudinal direction tends to vary when the optical fiber core wire is stored into a cable. On the other hand, it is known that the transmission performance of an optical fiber cable is influenced by the smoothness of the inner surface of the groove of the optical fiber housing spacer and the so-called “shape retention” that hardly deforms when a load is applied. For this reason, there is a demand for an optical fiber housing spacer that is excellent in the smoothness of the groove inner surface and has a highly accurate shape retention.

  In addition, by using the synthetic resin rod-like material manufactured by the method described in Patent Document 2 described above as the core, an optical fiber storage spacer having excellent smoothness of the groove inner surface can be obtained. The stability of transmission performance in the longitudinal direction is not sufficient.

  Then, this invention makes it the main objective to provide the manufacturing method of the optical fiber accommodation spacer which can obtain the stable transmission performance, when it is set as an optical fiber cable.

  As a result of intensive experiments to solve the above-mentioned problems, the present inventors have found that the transmission performance of the optical fiber cable is influenced not only by the shape of the groove inner surface but also by the fluctuation of the outer diameter of the spacer. I found. Specifically, when the outer diameter of the spacer fluctuates in the longitudinal direction, the rib portion (convex portion) of the spacer is pressed by an external pressure such as a covering outer shell when making the cable at a location where the outer diameter is large, The width and shape of the groove adjacent to the rib portion change. As a result, the optical fiber core housed in the groove is pressed and transmission loss increases.

  On the other hand, in a portion where the outer diameter of the spacer is small, the optical fiber core wire is directly pressed by an external pressure such as a covering sheath, and transmission loss increases. In addition, it is difficult to apply the feedback method described in Patent Documents 2 and 3 described above in a molded body that has irregularities on the surface due to groove formation and has a non-circular cross section, such as an optical fiber storage spacer. . Further, when the resin extrusion amount is fed back to the rotation speed of the gear pump as in the manufacturing method described in Patent Document 1, the resin main body portion is caused by deterioration of the resin, carbide, etc. in the continuous operation for a long time by using the gear pump. There is a concern that the smoothness of the groove inner surface may be reduced.

  Therefore, the present inventor further examined a manufacturing method that does not use a gear pump, and measured the outer diameter at a specific interval with regard to the spacer main body after forming the covering portion, assuming that the cross section is pseudo-circular. Accordingly, by adjusting the extrusion amount of the thermoplastic resin by the extruder, it has been found that fluctuations in the outer diameter of the resulting spacer can be suppressed, leading to the present invention.

That is, the manufacturing method of the optical fiber storage spacer according to the present invention includes an optical fiber storage provided with grooves that rotate in a certain direction in a spiral shape or grooves that rotate alternately in an SZ shape for storing optical fibers on the outer peripheral surface. A method of manufacturing a spacer, which is made of a thermoplastic resin around a center core by extrusion using a rotating die, and rotates alternately in one or a plurality of spiral grooves or SZs. The step of forming the covering portion including the groove to be formed, and the spacer body after forming the covering portion, the cross section is regarded as a pseudo circle, the outer diameter is measured, and the extrusion amount of the thermoplastic resin is determined according to the value A step of adjusting the extrusion amount, wherein the outer diameter is continuously measured in a section of ½ pitch or more of the groove, and the maximum value does not fall within a set range. Within the setting range Adjusting the extrusion amount countercurrent.
Here, one pitch of each groove is the length that the groove rotates once in a spiral rotating in a certain direction, and in the groove that rotates alternately in an SZ shape, the groove is inverted and the original pitch is reversed. It is the length until it returns to the position. Therefore, the 1/2 pitch of the groove is a half length of the above-mentioned 1 pitch, and is a specific length appropriately set according to the spacer to be manufactured.
In the present invention, the outer diameter of the spacer body after formation of the covering portion is continuously measured in a section of 1/2 pitch or more of the groove, and the thermoplastic resin is extruded when the maximum value does not fall within the set range. Since the amount is adjusted, the outer diameter can be accurately measured without being affected by the number, width, position, and the like of the grooves.
In this manufacturing method, when the outer diameter of the target spacer is d (mm) and the minimum control value of the outer diameter accuracy is a (mm), the outer diameter is measured by the following formula per 1/2 pitch of the groove. You may perform more than the number of times calculated | required by (1). In addition, the minimum management value a in the following mathematical formula (1) is an arbitrary constant selected from the range of 0.1 ≧ a ≧ 0.001. Further, π in the following mathematical formula (1) is a circumference ratio.

Also, when the outer diameter is continuously measured over 1 to 4 sections with a length of 1/2 pitch or more of the groove as one section, and the maximum value of each section never falls within the set range Only the extrusion amount can be adjusted.
Further, the amount of extrusion may be adjusted by changing the screw speed of the extruder.
Furthermore, the outer diameter of the spacer body can be measured by a laser outer diameter measuring device.

  According to the present invention, the outer diameter of the spacer body after forming the covering portion is continuously measured in a section of 1/2 pitch or more of the groove that rotates in a certain direction spirally or the groove that rotates alternately in the SZ shape. Because the extrusion amount of the thermoplastic resin is adjusted when the maximum value does not fall within the set range, there is little fluctuation in the outer diameter in the longitudinal direction, and stable transmission performance can be obtained when an optical fiber cable is used. An optical fiber storage spacer can be manufactured.

It is sectional drawing which shows an example of the spacer obtained by embodiment of this invention. It is a flowchart figure which shows the manufacturing method of the fiber accommodation spacer which concerns on embodiment of this invention. It is a figure which shows the structural example of the apparatus used in the manufacturing method of the fiber accommodation spacer which concerns on embodiment of this invention. It is sectional drawing which shows an example of the spacer obtained by the modification of embodiment of this invention. It is a figure which shows the structural example of the apparatus used in the manufacturing method of the fiber accommodation spacer which concerns on the modification of embodiment of this invention. It is a figure which shows the fluctuation | variation of the maximum value of the outer diameter in the continuous manufacture time of the spacer of Example 1, taking time on a horizontal axis and taking the outer diameter of a spacer on a vertical axis. It is a figure which shows the fluctuation | variation of the maximum value of the outer diameter in the continuous manufacture time of the spacer of Example 2 by taking time on a horizontal axis and taking the outer diameter of a spacer on a vertical axis. It is a figure which shows the fluctuation | variation of the maximum value of the outer diameter in the continuous manufacture time of the spacer of the comparative example 1 by taking time on a horizontal axis and taking the outer diameter of a spacer on a vertical axis | shaft. It is a figure which shows the fluctuation | variation of the maximum value of the outer diameter in the continuous manufacture time of the spacer of the comparative example 2 by taking time on the horizontal axis and taking the outer diameter of the spacer on the vertical axis. It is a figure which shows the fluctuation | variation of the maximum value of the outer diameter in the continuous manufacture time of the spacer of Example 3 by taking time on a horizontal axis and taking the outer diameter of a spacer on a vertical axis. It is a figure which shows the fluctuation | variation of the maximum value of the outer diameter in the continuous manufacture time of the spacer of the comparative example 3 by taking time on a horizontal axis and taking the outer diameter of a spacer on a vertical axis | shaft. (A) is a perspective view which shows an optical cable accommodation spacer provided with a SZ groove | channel, (b) is the sectional drawing.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments described below.

  First, an optical fiber storage spacer (hereinafter also simply referred to as “spacer”) obtained by a manufacturing method according to an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing an example of a spacer obtained by this embodiment. As shown in FIG. 1, the spacer 10 manufactured according to the present embodiment is spirally rotated in a fixed direction or alternately in an SZ shape around a resin-coated tensile body 3 in which a tensile strength line 1 is coated with a thermoplastic resin 2. A covering portion 4 having a rotating groove 5 is provided.

  Examples of the tensile strength wire 1 used in the spacer 10 include steel wires or those using high strength fibers such as glass fiber reinforced plastic, aramid fiber reinforced plastic, and polyparaphenylene benzobisoxazole fiber reinforced plastic. . In addition, as the thermoplastic resin 2, for example, polyethylene, polypropylene, polybutylene terephthalate, polyethylene terephthalate, or the like can be used. Furthermore, the coating | coated part 4 can also be formed with thermoplastic resins, such as polyethylene, a polypropylene, a polybutylene terephthalate, and a polyethylene terephthalate.

  At this time, the thermoplastic resin forming the covering portion 4 may be the same as that of the thermoplastic resin 2 of the resin-coated tensile body 3, but for example, the thermoplastic resin 2 of the resin-coated tensile body 3 is made of low-density polyethylene and is coated. Part 4 can also be formed of high density polyethylene.

  Next, the manufacturing method of the spacer 10 described above, that is, the manufacturing method of the optical fiber housing spacer according to the present embodiment will be described. FIG. 2 is a diagram showing a configuration example of an apparatus (hereinafter also referred to as “manufacturing apparatus”) used in the manufacturing method of the present embodiment. As shown in FIG. 2, in the manufacturing method of the spacer 10 of this embodiment, first, the resin-coated strength member 3 is formed (step S1).

  Specifically, the tensile strength wire 1 wound around a wire feeder (creel) 20 is pulled out and introduced into an extruder 21 equipped with a circular hole-shaped die. Then, in the extrusion molding machine 21, the thermoplastic resin 2 is extruded around the tensile strength wire 1, and the resin-coated tensile strength body 3 in which the periphery of the tensile strength wire 1 is coated with the thermoplastic resin 2 is obtained.

  Next, the coating portion 4 including one or a plurality of grooves 5 is formed on the outer periphery of the resin-coated tensile member 3 (step S2). Specifically, the resin-coated tensile member 3 obtained in step S1 is introduced into an extrusion molding machine 22 equipped with a rotary die having a predetermined shape, and the die is formed in the Z direction with respect to the insertion direction of the resin-coated tensile member 3. The thermoplastic resin is extruded while rotating the die or reversing the rotation direction of the die at regular intervals in the SZ shape. Thereby, the coating | coated part 4 provided with the Z spiral-shaped or SZ-shaped groove | channel 5 is formed in the circumference | surroundings of the resin coating tensile strength body 3. FIG.

  At this time, the extrusion amount of the thermoplastic resin is adjusted based on the result of outer diameter measurement described later. The amount of extrusion can be adjusted, for example, by changing the screw rotation speed of the extrusion molding machine 22. Thereby, the outer diameter accuracy in the longitudinal direction can be improved.

  Subsequently, in the cooling part 23, the resin constituting the covering part 4 is completely solidified to obtain the optical fiber housing spacer 10 (step S3). The cooling method at that time is not particularly limited, and a water cooling method, an air cooling method, and a cooling method using a heating / cooling tube can be appropriately selected and applied, and these methods can be used in combination.

  Thereafter, the outer diameter of the obtained spacer 10 is measured, and the result is fed back to the step of forming the covering portion 4 in step S2 (step S4). Specifically, first, in the section (length) of 1/2 pitch or more of the spiral or SZ-shaped groove 5 formed in the covering portion 4 by the outer diameter measuring device 25, the spacer body (spacer after cooling) is cooled. The outer diameter of 10) is continuously measured several times. When the maximum value does not fall within the set range, the control device 24 adjusts the extrusion amount of the thermoplastic resin in step S2 so that the maximum value of the outer diameter falls within the set range.

  As the outer diameter measuring instrument 25 used here, for example, a laser outer diameter measuring instrument can be used. In this case, the length of the laser beam blocked by the spacer 10 may be regarded as the outer diameter and measured.

  On the other hand, the spacer 10 has a Z-spiral or SZ-shaped groove 5 formed on the outer surface, and the length of the laser beam blocked by the groove 5 is measured and determined as the outer diameter. Then, the value is smaller than the actual spacer outer diameter. In particular, when the spacer 10 in which the SZ groove is formed is measured using a laser outer diameter measuring device, the portion where the extending direction of the groove 5 is reversed is more than the portion where the groove 5 is rotated in one direction. However, the length that the laser beam is blocked is further shortened. Therefore, in the spacer manufacturing method of this embodiment, in order to increase the reliability of the measurement value, the outer diameter is continuously measured for a certain section, and the maximum value is defined as the “outer diameter” in the section.

  The “certain section” here is specifically a section (length) of 1/2 pitch or more of the spiral or SZ-shaped groove 5. When the spacer 10 passes through the outer diameter measuring device 25, the groove 5 formed on the outer surface thereof rotates in the relative relationship. On the other hand, the outer diameter of the spacer 10 may be measured by measuring the diameter of the cross section thereof, so that the spacer 10 is at least a length corresponding to ½ rotation of the groove 5, that is, the length of ½ pitch of the groove 5. In this case, the length for blocking the laser beam may be measured.

  For example, when measuring using a laser outer diameter measuring instrument, if the measurement section (length) is less than ½ pitch of the groove 5, it cannot be determined that the maximum value of the length that blocks the laser beam correlates with the outer diameter. As a result, fluctuations in the outer diameter increase. At that time, it is desirable that the number of times of measurement of the outer diameter be equal to or more than the number obtained by the following mathematical formula (2) per ½ pitch of the groove. In the following mathematical formula (2), d is the outer diameter (mm) of the target spacer, a is the minimum control value (mm) of the outer diameter accuracy, and π is the circumference.

  By measuring more than the number of times required by the above equation (2) per ½ pitch of the groove, the measured outer diameter variation rate of the spacer can be further reduced, and thus the transmission loss reduction suppressing effect is improved. As a result, it is possible to simplify the outer diameter measurement for quality control separately performed, which leads to a reduction in the number of processes.

  Here, the minimum control value a (mm) of the outer diameter accuracy is the minimum unit of length for determining the outer diameter in order to correspond to the required outer diameter quality as the spacer, and the spacer manufacturing method of the present embodiment In this case, the range is 0.1 ≧ a ≧ 0.001. For example, when the minimum management value a is set to 0.01 mm, the accuracy of the outer diameter measuring device 25 needs to be a value one digit smaller than that. Specifically, the error when measuring by moving a standard round bar of φ20 mm within the measurement region of the outer diameter measuring instrument 25 is within a range of ± 0.003 mm (error width of 0.006 mm or less). desirable.

  In addition, the value obtained by the above equation (2) is obtained by dividing the cross-sectional half circumference of the spacer 10 by the error width on the circumference corresponding to the error width (minimum control value a of the outer diameter accuracy) in the diameter to be detected. (Divided) value. For example, when the measurement is performed using a laser outer diameter measuring instrument, the diameter of the spacer 10 is determined by measuring the length that blocks the laser beam. For this reason, the spacer 10 in which the groove 5 is formed is a length that blocks the laser beam while making a half rotation in the relative positional relationship with the outer diameter measuring instrument whose position is fixed as it advances. Is measured more than the number of times obtained by the above equation (2), the diameter is measured with an accuracy greater than the error width to be detected over the entire circumference.

  The outer diameter value measured by the above-described method is preferably fed back quickly to the extrusion amount of the thermoplastic resin of the extruder 22. On the other hand, it is difficult to stably measure the outer diameter of the spacer 10 after extrusion unless it is sufficiently cooled and the internal structure is fixed. For this reason, in the manufacturing method of the spacer of this embodiment, the cooling unit 23 is provided between the extrusion molding machine 22 and the outer diameter measuring device 25, and thus the outer diameter is measured after the formation of the covering portion 4. It takes a certain distance until

  For this reason, it is desirable that the distance between the extrusion molding machine 22 to be fed back and the outer diameter measuring device 25 be as short as possible and be placed close to each other. However, in the cooling unit 23 described above, it is necessary to sufficiently cool the spacer 10 so that the shape of the spacer 10 is stabilized. Therefore, in practice, the cooling unit 23 has to be disposed at a distance of about 5 to 20 m. Further, when the measurement result is immediately fed back in order to eliminate the deviation between the measurement result of the outer diameter measuring instrument 25 and the actual setting range, the fluctuation is increased (depending on the conveyance speed, etc.). Hunting).

  In order to prevent such a situation, it is possible to determine a maximum value in a determination interval of 1/2 pitch or more of the spiral or SZ-shaped groove 5 and repeat this several times to continuously determine progress. desirable. That is, the length of 1/2 pitch or more of the groove 5 is one section, and the outer diameter of the spacer body (spacer 10) after cooling is continuously measured over one to four sections, and the maximum value of each section is once Only when it does not fall within the set range, it is desirable to adjust the extrusion amount of the thermoplastic resin in step S2 in the control device 24 in such a direction that the maximum value of the outer diameter falls within the set range. In addition, if it is within the set range even once, it may be determined in the subsequent progress without feedback.

  Since the number of continuous judgments (section for continuous measurement) is related to the distance between the extrusion molding machine 22 and the outer diameter measuring instrument 25 and the conveying speed of the spacer 10, this distance is divided by the speed. It can be set within the range of an integer or less. Specifically, it is desirable that the continuous measurement interval for the progress determination is 1 to 4 intervals. In addition, since hunting may occur if it is determined by the measurement of one section, the preferable number of sections for continuous measurement is 2 to 4 sections.

  Further, continuous measurement may be performed for five or more sections, but in that case, the feedback effect may be reduced, and the fluctuation range of the outer diameter may increase in the same direction as when feedback control is not performed. That is, the effect decreases. For this reason, it is desirable that the number of sections to be continuously measured is appropriately set in the range of 2 to 4 sections after once confirming the variation of the outer diameter value at the time of manufacture. Thereby, the stability of the outer diameter in the longitudinal direction can be improved.

  The spacer 10 whose outer diameter is measured in step S4 is then wound up by the winder 26 (step S5).

  As described in detail above, in the spacer manufacturing method of the present embodiment, the outer diameter of the spacer body after forming the covering portion is continuously measured in a section having a pitch of 1/2 or more of the spiral groove or the SZ groove. Since the extrusion amount of the thermoplastic resin is adjusted when the maximum value does not fall within the set range, it is possible to manufacture a spacer with little fluctuation in the outer diameter in the longitudinal direction. By using this optical fiber housing spacer, an optical fiber cable with stable transmission performance in the longitudinal direction can be obtained.

  The manufacturing method of the optical fiber storage spacer according to the present invention is limited to the structure shown in FIG. 1, that is, the one using the resin-coated tensile member 3 in which one tensile wire 1 is coated with one layer of thermoplastic resin 2. Is not to be done. FIG. 4 is a cross-sectional view showing an example of a spacer obtained in a modification of the embodiment of the present invention. Specifically, a twisted steel wire obtained by twisting a plurality of steel wires as shown in FIG. 4 is used as a tensile strength wire 6, and two different types of thermoplastic resins 7 a and 7 b are sequentially coated around the tensile strength wire 6. The spacer 11 can also be manufactured using the resin-coated tensile member 8.

  FIG. 5 is a view showing a configuration example of an apparatus used in a method for manufacturing a fiber storage spacer according to a modification of the embodiment of the present invention. In that case, for example, as shown in FIG. 5, an extruder 27 having a circular hole die may be installed between the extruder 21 and the extruder 22. Then, after the periphery of the tensile strength wire 6 is coated with the thermoplastic resin 7 a by the extrusion molding machine 21, the thermoplastic resin 7 b is further extruded around the tensile strength wire 6 by the extrusion molding machine 27 to form the resin-coated tensile strength body 8.

  The configuration and effects other than those described above in the present modification are the same as those in the above-described embodiment. In the above-described embodiment and its modifications, the tensile body and the spacer are manufactured continuously. However, the present invention is not limited to this, and a tensile body manufactured in another process is used. Thus, the spacer can be manufactured. Furthermore, the manufacturing method of the spacer according to the present embodiment and its modification can be applied to both the spiral and SZ-shaped spacers, and the cross-sectional shape of the grooves is not particularly limited.

  Hereinafter, the effects of the present invention will be specifically described with reference to Examples and Comparative Examples of the present invention. In this example, optical fiber storage spacers of examples and comparative examples having spiral grooves were manufactured by the method described below, and the degree of fluctuation of the outer diameter was evaluated.

<Example 1>
Using the apparatus shown in FIG. 3, an optical fiber housing spacer (Z spiral groove, target outer diameter 15.0 mm, pitch 500 mm) having the structure shown in FIG. 1 was manufactured. Specifically, a single steel wire having a diameter of 2.3 mm is used as the tensile strength wire 1, and this is inserted into a molding head of an extrusion molding machine 21 having a circular hole-shaped die, and adhesive polyethylene is formed on the outer periphery thereof. And linear low-density polyethylene (LLDPE) were coextruded to obtain a resin-coated tensile body (primary resin-coated tensile line) 3 having an outer diameter of 5.7 mm.

  Next, the resin-coated strength member 3 was inserted into a molding head of an extrusion molding machine 22 provided with a die having a modified hole shape having five inner protrusions. Then, the die is rotated at a speed of 10 rotations / minute in the Z direction with respect to the insertion direction (hereinafter referred to as “rotary die molding”), and coated with high-density polyethylene resin, and molded at a take-up speed of 5 m / minute. Thus, the covering portion 4 was formed. Then, it led to the water cooling type cooling part 23, cooled, and obtained the spacer 10 in which the spiral groove 5 was formed by die rotation. The pitch (the length with which the groove makes one rotation) in the spacer of Example 1 was 500 mm.

  Subsequently, an outer diameter measuring device 25 (manufactured by Keyence Corporation) composed of a light emitting diode (LED) light projecting portion and a CCD (Charge Coupled Device Image Sensor) light receiving portion is passed, and the outer diameter of the spacer 10 thus obtained is obtained. The measurement result was fed back by the control device 24 to the resin extrusion amount of the extrusion molding machine 22 equipped with a rotating die.

At that time, the feedback conditions were set as follows.
(1) Outer diameter set value Center value: 14.97 mm, maximum value: 14.98 mm, minimum value: 14.96 mm
(2) Measuring speed by outer diameter measuring instrument 25: 2400 times / second (3) Measuring accuracy of outer diameter measuring instrument: ± 3 μm (error width: 6 μm)
(4) Continuous measurement length for obtaining the maximum value by the outer diameter measuring instrument (one section): 250 mm (corresponding to 1/2 of the pitch of the groove 5)
(5) Number of measurement intervals for determining necessity of feedback: 4 intervals (6) Feedback determination condition: The maximum value when continuously measuring 4 intervals is between the maximum value and the minimum value of the setting range even once. If there is no feedback. On the other hand, when all of the four sections are continuously outside the set range, the controller 24 increases or decreases the amount of resin extruded in the extruder 22 so that the maximum value of the outer diameter falls within the set range.

  Production was carried out continuously for 5 hours under the method and conditions described above. The required number of measurements per groove 1/2 pitch obtained by the above formula (2) is 750 times or more, whereas the actual number of measurements was 7200 times per 1/2 pitch of the groove 5. It was.

  FIG. 6 is a graph showing the variation of the maximum value of the outer diameter within the continuous manufacturing time of the spacer of Example 1 with time on the horizontal axis and the outer diameter of the spacer on the vertical axis. The spacer of Example 1 had an average outer diameter of 14.98 mm and a variation rate of 0.40%, and as shown in FIG. 6, the change in the outer diameter in the longitudinal direction was small. In addition, the fluctuation rate was calculated | required by following Numerical formula (3).

<Example 2>
The same method as in Example 1 described above, except that an outer diameter measuring device 25 (manufactured by Keyence Corporation) comprising a red light semiconductor laser light projecting portion and a CCD light receiving portion is used and the outer diameter measuring speed is set to 400 times / second. And the conditions were continuously produced for 5 hours. In the spacer of Example 2, the required number of measurements per groove 1/2 pitch obtained by the above equation (2) is 750 times or more, whereas the actual number of measurements is 1/2 that of the groove 5. It was 1200 times per pitch.

  FIG. 7 is a graph showing the variation of the maximum value of the outer diameter within the continuous manufacturing time of the spacer of Example 2, with time on the horizontal axis and the outer diameter of the spacer on the vertical axis. The spacer of Example 2 had an average outer diameter of 14.94 mm and a variation rate of 0.47%. As shown in FIG. 7, the outer diameter changed little in the longitudinal direction.

<Comparative Example 1>
The continuous measurement length (one section) for obtaining the maximum value by the outer diameter measuring instrument 25 is 125 mm (corresponding to the 1/4 pitch of the groove 5), and the same method and conditions as in Example 2 described above are used. And manufactured for 5 hours. In the spacer of Comparative Example 1, the required number of measurements per groove 1/2 pitch obtained by the above formula (2) is 750 times or more, whereas the number of times actually measured is 1 for the groove 5. It was 600 times per 2 pitches, and the number of measurements defined in claim 2 was not reached.

  FIG. 8 is a graph showing the variation of the maximum value of the outer diameter within the continuous manufacturing time of the spacer of Comparative Example 1, with the time on the horizontal axis and the outer diameter of the spacer on the vertical axis. The spacer of Comparative Example 1 had an average value of 14.92 mm, but since the continuous measurement length (one section) was less than ½ pitch of the groove 5, the variation rate was as high as 0.60%, As shown in FIG. 8, the change in the outer diameter in the longitudinal direction was large.

<Comparative example 2>
Production was carried out continuously for 5 hours under the same method and conditions as in Example 1 except that feedback control of the resin extrusion amount based on the measurement result of the outer diameter was not performed. FIG. 9 is a diagram showing the variation of the maximum value of the outer diameter within the continuous manufacturing time of the spacer of Comparative Example 2, with the horizontal axis representing time and the vertical axis representing the outer diameter of the spacer. The average value of the spacer of Comparative Example 2 was 14.96 mm, but since the resin extrusion amount was not feedback controlled, the variation rate was as high as 0.60%, and as shown in FIG. The change in outer diameter was large.

<Example 3>
Using the apparatus shown in FIG. 5, an optical fiber housing spacer (Z spiral groove, target outer diameter 23.3 mm, pitch 500 mm) having the structure shown in FIG. 4 was manufactured. Specifically, a stranded steel wire in which seven steel wires having a diameter of 1.2 mm are twisted is used as the tensile strength wire 6, and this is inserted into the molding head of the extrusion molding machine 21 having a circular hole-shaped die. Then, adhesive polyethylene was extruded to the outer periphery to obtain a primary resin-coated tensile strength line. Subsequently, the primary resin-coated tensile strength line is inserted into a molding head of an extrusion molding machine 27 having a circular hole-shaped die, and linear low-density polyethylene (LLDPE) is extruded on the outer periphery thereof, thereby forming a secondary resin-coated tensile strength line. (Resin-coated tensile member 8).

  Next, this resin-coated strength member 8 was inserted into a molding head of an extrusion molding machine 22 provided with a die having a deformed hole shape having 13 inner protrusions. Then, while rotating the die in the Z direction with respect to the insertion direction at a speed of 5 rotations / minute (hereinafter referred to as rotary die molding), the high-density polyethylene resin is coated and the take-up speed is 2.5 m / minute. To form the covering 4. Then, it led to the water cooling type cooling part 23, cooled, and obtained the spacer 10 in which the spiral groove 5 was formed by die rotation. The pitch (the length with which the groove makes one rotation) in the spacer of Example 3 was 500 mm.

  Then, while passing through an outer diameter measuring device 25 (manufactured by Keyence Corporation) consisting of a green light emitting LED light projecting portion and a CCD light receiving portion, and measuring the outer diameter of the obtained spacer 10, The amount of resin extruded from the extrusion molding machine 22 equipped with a rotating die was fed back.

At that time, the feedback conditions were set as follows.
(1) Outer diameter set value Center value: 23.34 mm, maximum value: 23.35 mm, minimum value: 23.33 mm
(2) Measuring speed by outer diameter measuring instrument 25: 2400 times / second (3) Measuring accuracy of outer diameter measuring instrument: ± 3 μm (error width: 6 μm)
(4) Continuous measurement length for obtaining the maximum value by the outer diameter measuring instrument (one section): 250 mm (corresponding to 1/2 of the pitch of the groove 5)
(5) Number of measurement intervals for determining necessity of feedback: 4 intervals (6) Feedback determination condition: The maximum value when continuously measuring 4 intervals is between the maximum value and the minimum value of the setting range even once. If there is no feedback. On the other hand, when all of the four sections are continuously outside the set range, the controller 24 increases or decreases the amount of resin extruded in the extruder 22 so that the maximum value of the outer diameter falls within the set range.

  Production was continuously performed for 24 hours under the method and conditions described above. The necessary number of measurements per groove 1/2 pitch obtained by the above formula (2) is 1165 times or more, whereas the actual number of measurements was 14400 times per 1/2 pitch of the groove 5. It was.

  FIG. 10 is a graph showing the variation of the maximum value of the outer diameter within the continuous manufacturing time of the spacer of Example 3 with time on the horizontal axis and the outer diameter of the spacer on the vertical axis. The spacer of Example 3 had an average outer diameter of 23.36 mm and a variation rate of 0.17%. As shown in FIG. 10, the change in the outer diameter in the longitudinal direction was very small. .

<Comparative Example 3>
Production was continuously performed for 24 hours under the same method and conditions as in Example 3 described above, except that feedback control of the resin extrusion amount based on the measurement result of the outer diameter was not performed. FIG. 11 is a graph showing the variation of the maximum value of the outer diameter within the continuous manufacturing time of the spacer of Comparative Example 3, with the horizontal axis representing time and the vertical axis representing the outer diameter of the spacer. The average value of the spacer of Comparative Example 3 was 23.37 mm, but since the resin extrusion amount was not feedback controlled, the variation rate was 0.30%, which is higher than the spacer of Example 3 described above. As shown in FIG. 10, the change in the outer diameter in the longitudinal direction was large.

  As described above, when the spacer having the structure of FIG. 1 is manufactured, the spacers of Examples 1 and 2 manufactured by the manufacturing method of the present invention are the comparative example 1 and the feedback in which the feedback condition is out of the scope of the present invention. The variation rate of the outer diameter (measured maximum value) was smaller than that of the spacer of Comparative Example 2 that was not controlled. Moreover, even if the fluctuation diagrams of FIGS. 6 to 9 were compared, Examples 1 and 2 showed a more stable transition than Comparative Examples 1 and 2.

  Similarly, when the spacer having the structure shown in FIG. 4 is manufactured, the spacer of Example 3 manufactured by the manufacturing method of the present invention has an outer diameter (measurement maximum) compared to the spacer of Comparative Example 3 in which feedback control was not performed. Value) was small. Moreover, even if the variation diagrams of FIG. 10.11 were compared, Example 3 showed a more stable transition than Comparative Example 3. Note that the variation rate of the spacer of Comparative Example 3 is lower than the variation rate of the spacers of Examples 1 and 2 described above, but this is due to different manufacturing conditions and the like. In the case, the absolute value of the fluctuation rate cannot be compared.

  From the above results, it was confirmed that the spacer manufacturing method of the present invention can suppress fluctuations in the outer diameter in the longitudinal direction and is excellent as a manufacturing control method. And according to this invention, it was proved that the optical fiber accommodation spacer which can obtain the stable transmission performance when there was little fluctuation | variation of the outer diameter in a longitudinal direction and it was set as the optical fiber cable was proved.

DESCRIPTION OF SYMBOLS 1,6 Tensile wire 2,7a, 7b Thermoplastic resin 3,8,101 Tensile body 4 Covering part 5,103 Groove 10,11,100 Optical fiber accommodation spacer 20 Wire feeder 21, 22, 27 Extruder 23 Cooling 24 Control device 25 Outer diameter measuring device 26 Winder 102 Spacer body

Claims (5)

A method of manufacturing an optical fiber storage spacer provided with grooves that rotate spirally in a certain direction or grooves that rotate alternately in an SZ shape for storing optical fibers on an outer peripheral surface,
By extrusion molding using a rotating die, a covering portion made of a thermoplastic resin and having a groove rotating in one or more spirals in a certain direction or a groove rotating alternately in an SZ shape is formed around the center core. Process,
For the spacer body after the covering portion is formed, the cross section is regarded as a pseudo circle, the outer diameter is measured, and the extrusion amount of the thermoplastic resin is adjusted according to the value,
In the step of adjusting the extrusion amount, the outer diameter is continuously measured in a section of ½ pitch or more of the groove, and the optical fiber is accommodated to adjust the extrusion amount when the maximum value does not fall within the set range. Manufacturing method of spacer. When the outer diameter of the target spacer is d (mm) and the minimum control value of the outer diameter accuracy is a (mm), the measurement of the outer diameter is obtained by the following formula (A) per ½ pitch of the groove. The method for manufacturing an optical fiber storage spacer according to claim 1, wherein the method is performed more than a predetermined number of times.

  The length of the groove of 1/2 pitch or more is one section, the outer diameter is continuously measured over 1 to 4 sections, and the extrusion amount is only when the maximum value of each section never falls within the set range. The method for manufacturing an optical fiber storage spacer according to claim 1, wherein the optical fiber accommodation spacer is adjusted.   The method for manufacturing an optical fiber storage spacer according to any one of claims 1 to 3, wherein the amount of extrusion is adjusted by changing a screw rotation speed of an extruder.   The method for manufacturing an optical fiber storage spacer according to any one of claims 1 to 4, wherein the outer diameter of the spacer main body is measured by a laser outer diameter measuring instrument.

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