JP3429343B2 - Manufacturing method of single groove slot - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a single-groove slot having only one groove for accommodating a core of an optical fiber tape. 2. Description of the Related Art Optical fiber cables are currently used as cables for subscribers in public communication, and generally include a plurality of optical fiber tape cores and a slot for accommodating and holding the tape cores. It has a structure in which a plurality of slots are aggregated. By the way, communication using an optical fiber cable will be further expanded to each home in the future, and in such a situation, this kind of optical fiber cable is expected to be used as a cable connected to each home. . [0003] However, if the application is expanded to such a range, the cost of the optical fiber cable needs to be greatly reduced compared to the existing one, and it is realized whether or not such a demand can be met. Has become an important point. To meet such demands, it is necessary to greatly increase the number of optical fiber core wires per unit cross-sectional area of the cable. As means for realizing this, the ratio of the storage groove to the cross-sectional area of the slot is increased, and the silicon buffer layer or the photo-curable resin coating layer of the optical fiber tape core wire stored in the groove is made thinner. Densification has been achieved. However, if the thickness of the silicon buffer layer or the photo-curable resin coating layer of the optical fiber tape core is reduced, the effect of the dimensional accuracy and surface roughness of the storage groove becomes extremely susceptible. This causes an increase in transmission loss. In order to solve such a problem, it is necessary to improve the dimensional accuracy of the storage groove as compared with the conventional slot. In particular, there is no swelling of the groove bottom and the vertical wall of the storage groove, Important requirements are that the vertical wall and the vertical wall have a small surface roughness. By the way, this kind of one-groove slot is a kind of extruded molded product, and such an extruded product is usually manufactured by a continuous molding method. As a method for producing a continuously extruded product having an irregular cross section, three production methods described below have been conventionally known. First Manufacturing Method (Deformed Extrusion → Cooling in Open State) A thermoplastic resin in a molten state is extruded from a die having a shape close to a desired cross-sectional shape, and then cooled as it is by water cooling or air cooling to form a molded product. How to get. This manufacturing method has the simplest equipment and process and is inexpensive, and has a high production speed. However, the dimensional accuracy of the obtained molded product is low. Second manufacturing method (deformed extrusion → cooling in open state →
Heating → Sizing) The molded product obtained by the production method is heated at a temperature higher than the softening point of the resin but lower than the melting point, drawn into a sizing die having a desired shape, and the shape is corrected and shaped while cooling. . This manufacturing method has good dimensional accuracy, but wastes energy for reheating and has a large pull-out resistance, so that the production speed is slow, and when a tension member is inserted inside the slot, or when a material having a high tensile strength is used. Applicable only to Third Manufacturing Method (Deformed Extrusion → Sizing) A method in which the extruded resin is drawn into a sizing die while being still at a temperature above the softening point and below the melting point, and is cooled and straightened and shaped. This manufacturing method is close to, but does not require a heating device, is economical and has good dimensional accuracy. However, such a conventional manufacturing method and the obtained slot have the following technical problems. [0007] That is, as shown in FIG. 1, the one-groove slot usually has a main body 1 having a substantially circular cross section.
And a substantially concave optical fiber tape core wire accommodating groove 2 formed in the main body 1 so that one end is opened.
In the slot having such a cross-sectional shape, a portion located on the outer periphery between the groove bottom surface 2a and the pair of vertical wall surfaces 2b of the storage groove 2 has a substantially semicircular shape, and there is a large difference in wall thickness. As a result, the cooling rate differs between the thick part and the small part, resulting in a difference in the shrinkage rate of the molded product.
The vertical wall surface 2b corresponding to the thickest portion swells (the same phenomenon as sink occurs). This trend is
Increasing the production speed makes it stronger. Such a problem,
In the above-described manufacturing method, this also occurs in the third manufacturing method in which good results are obtained in dimensional accuracy,
This has been an obstacle in increasing the density of optical fiber cables. [0009] The present invention was made in view of such conventional problems, and an object, Ichimizo slot that the dimensional accuracy of the receiving grooves of the optical fiber tape core wire can be satisfactorily ensured It is to provide a manufacturing method of. [0010] In order to achieve the above object, the present invention provides a main body having a substantially circular cross section and one main body.
A generally concave optical fiber tape with an open end
Presses the molten thermoplastic resin.
After taking out the thermoplastic resin while shaping the storage groove
Method for manufacturing a single groove slot formed by cooling
The cross section used for extruding the thermoplastic resin is substantially circular.
The cross section of the extrusion die is formed on the outer periphery of the storage groove.
Notch on the outer periphery of the part corresponding to the thick part of the main body
Saijin for shaping and cooling
The cross-sectional shape of the die is the outer circumference of the notch of the extrusion die.
A space is formed in a substantially circular shape, and cooling water is supplied to the space.
It is characterized by supplying . It is desirable that the cutout has a cross-sectional area of not more than 20% of a cross-sectional area of the slot body . As a sizing die used for carrying out the present invention, for example, a cylinder obtained by dividing a cylindrical body into two parts is connected, and a gap having a shape similar to the cross-sectional shape of the slot is formed at the connection part. Such a sizing die can be used in a cylindrical shape provided with a cooling jacket for circulating cooling water, or in a state in which the cylindrical body is supported in water. In addition, the abutting state between the wall surface of the sizing die and the extruded molded product requires that the entire periphery of the storage groove abut, but the outer periphery of the slot does not require dimensional accuracy as much as the groove portion. It is not necessary that the entire periphery of the sizing die abut on the sizing die. According to the method for manufacturing a single-groove slot having the above structure,
Cross section used to extrude thermoplastic resin in one groove slot
Formed the cross-sectional shape of the substantially circular extrusion die on the outer periphery of the storage groove
Notch on the outer periphery of the part corresponding to the thick part of the main body
Sizing die for shaping and cooling
The cross-sectional shape of the
The cooling water is introduced into the space to cool the thick portion strongly, and the cooling water introduced into this space can function as if it were a lubricant. Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Example 1 First, in this example, the design cross-sectional shape was set as shown in FIG. In FIG. 1, reference numeral 1 denotes a main body having a substantially circular cross-section formed of a thermoplastic resin. At the center of the circular cross-section of the main body 1, a storage groove 2 having one open end is provided. The main body 1 has a bottom 1a and a pair of vertical walls 1b, and a tension member 3 is disposed at the center of each of the bottom 1a and the vertical wall 1b. Storage groove 2
Has a groove bottom surface 2a and a pair of vertical wall surfaces 2b rising vertically from both ends of the groove bottom surface 2a, and is formed in a substantially concave shape. The outer diameter R of the main body 1 is 6.2 mm, the groove width W of the storage groove 2 is 3.8 mm, and the depth D of the storage groove 2 is
It was set to 3.3 mm. A single-groove slot having such a designed cross-sectional shape was manufactured by the method shown in FIG. In the method shown in FIG.
A 0-denier aramid fiber (manufactured by Toray Dupont Co., Ltd., trade name: Kevlar 49) is prepared, and the creel stand
Wound to zero. The resin for forming the main body 1 is PB
T resin (manufactured by Teijin Limited: trade name C-7000N) was prepared and supplied to the extruder 12 in a molten state. The tension member 3 adjusts the supply tension to 4 through a plurality of guide rollers 14 in order to arrange the three members at predetermined positions.
The extruder 12 is supplied to the crosshead 12 a of the extruder 12 by passing the preform into the preheating device 16 at 50 g / line. The extrusion temperature of the resin by the extruder 12 was set to 245 ° C. The cross-sectional shape of the discharge portion of the die 12b mounted on the cross head 12a of the extruder 12 was set to a shape as shown in FIG. The cross-sectional shape shown in the figure is a shape in which the outer periphery of the bottom 1a of the main body 1 is cut out so as to be parallel to the groove bottom 2a of the storage groove 2 with respect to the designed cross-sectional shape of the slot shown in FIG. ing. The ratio of the notch at this time was set to 4.7%. The calculation of this ratio is substantially the same in each of the following examples. In this example, a circle without a notch is assumed in FIG. 3, and the sectional area of the groove is calculated from the sectional area of the circle. Is calculated as S ₁ / S ₀ × 100%, where S ₀ is the value obtained by subtracting the above and S ₁ is the cross-sectional area of the notch. The molded product extruded from the die 12b having such a cross-sectional shape is then introduced into a sizing die 18, where it is shaped and cooled, passes through a plurality of guide rollers 20, and is taken up by a take-up machine 22 at a take-up speed of 4. It is picked up at 0 m / min. [0019] shows a detail of Sizing Gudai 18 using this time to FIG. Sizing Gudai 18 shown in FIG.
Is composed of a material having good thermal conductivity such as metal, has an enlarged head portion 18a and a cylindrical portion 18b, and joins two portions divided at the center along the longitudinal direction. In addition, a void portion 18c having a shape similar to the design cross-sectional shape of the slot and slightly larger than that is formed in this coupling surface. The cylindrical portion 1 of the sizing die 18
A cylindrical cooling jacket 18e provided with an insertion hole 18d of the saijin die 18 at the center is arranged on the outer peripheral surface of the outer peripheral surface of the jacket 18e so that a cooling water intake 18f is formed on the outer peripheral surface of the jacket 18e. An outlet 18g is provided. FIG. 5 shows a cross-sectional shape of a single groove slot obtained by the above-described manufacturing method. Sectional area of the first groove slot shown in the figure, 15.16mm ² (cross-sectional area of the design 1
5.96 mm ² , 94.98%), and the contact ratio with the sigig die 18 was 72.1%. The bulge of the groove bottom surface 2a and the vertical wall surface 2b of the storage groove 2 is 0.0
5 mm or less, which satisfied the accuracy (0.2 mm or less) required for a single-groove slot for high density. The calculation of the cross-sectional area of the slot and the like is obtained according to a method described later. Example 2 The set cross-sectional dimensions were set as shown in Table 1 with respect to Example 1, and the cross-sectional shape of the projecting portion of the die 12b mounted on the crosshead 12a of the extruder 12 is shown in FIG. A single-groove slot was manufactured under the same conditions except that the shape was set as shown. The cross-sectional shape of the die 12b shown in FIG.
With respect to the design sectional shape of the slot shown in FIG. 1, the outer periphery of the bottom 1 a of the main body 1 is cut out so as to be parallel to the groove bottom 2 a of the storage groove 2, and the vertical portion 1 b of the main body 1 is formed. The outer periphery is cut out so as to be parallel to the vertical wall surface 2b of the storage groove 2, that is, the outer periphery of the installation position of the tension member 3, and the notch is located on both sides of the tension member 3 as a center. It has become. At this time, the ratio of the notch was 1.9% at the bottom and 1.9% at both sides. FIG. 7 shows a cross-sectional shape of a single groove slot obtained by the above-described manufacturing method. The cross-sectional area of the single-groove slot shown in the figure is 26.43 mm ² (designed cross-sectional area 2
(88.7% of 9.79 mm ² ).
The contact ratio with No. 8 was 41.1%. The bulge of the groove bottom surface 2a and the vertical wall surface 2b of the storage groove 2 is 0.10.
mm and 0.11 mm, which satisfied the precision (0.2 mm or less) required for a single-groove slot for high density. COMPARATIVE EXAMPLE 1 Compared to Example 1, the cross-sectional shape of the projecting portion of the die 12b mounted on the crosshead 12a of the extruder 12 was such that no cutout as shown in FIG. 3 was provided. A single groove slot was manufactured under the same conditions except for the above. However,
In this method, the molded product was clogged at the entrance of the sizing die after about one hour due to fluctuations in the take-up speed and the discharge amount, and stable production could not be continued. The cross-sectional shape of the slot obtained at the beginning is as shown in FIG. 8, and the cross-sectional area of the single-groove slot shown in FIG. 8 is 15.62 mm ² (designed cross-sectional area of 15.96 mm ² . 97.86%),
The contact ratio with the sigig die 18 was 89.86%. The bulge of the groove bottom surface 2a and the vertical wall surface 2b of the storage groove 2 is 0.24 mm and 0.18 mm, and satisfies the accuracy (0.2 mm or less) required for a single-groove slot for high density. I didn't. Comparative Example 2 The sectional shape of the projecting portion of the die 12b mounted on the cross head 12a of the extruder 12 was enlarged from that shown in FIG. A single groove slot was manufactured under the same conditions except that the ratio was 9.5%. The cross-sectional shape of the obtained slot is as shown in FIG. 9, and the cross-sectional area of the single-groove slot shown in FIG. 9 is 12.0 mm ² (designed cross-sectional area of 15.96
mm ² was 75.20%), and the contact ratio with the sigig die 18 was 52.4%. The bulge of the groove bottom surface 2a and the vertical wall surface 2b of the storage groove 2 is 0.22 mm,
0.23 mm, which did not satisfy the precision (0.2 mm or less) required for a single-groove slot for high density. Comparative Example 3 The sectional shape of the projecting portion of the die 12b mounted on the crosshead 12a of the extruder 12 was enlarged from that shown in FIG. A single groove slot was manufactured under the same conditions except that the percentage was 3% at the bottom and 10% at both sides. The resulting cross-sectional shape of the slot, there is in the state shown in FIG. 10, the cross-sectional area of the first groove slot shown in the figure, 16.7 mm ² (cross-sectional area 20.74Mm ² design 80. 51%), and the contact ratio with the sigig die 18 was 25.2%. Further, the bulges of the groove bottom surface 2a and the vertical wall surface 2b of the storage groove 2 are 0.23 mm and 0.22 mm, and the precision required for a single groove slot for high density (0.2 mm
Below) was not satisfied. Table 1 below summarizes the dimensions and the like of the slots of the above embodiment and comparative example. [Table 1] * The actual cross-sectional area of the slot body 1 is cut to a length (L) of about 10 cm, its weight (W) g and the density (ρ) obtained by the underwater replacement method. The cross-sectional area S ₁ cm ² was determined. S ₁ = W / L · ρ * Calculation of ratio (X) of sizing die and abutting portion As shown in FIG. And the angle β corresponding to the storage groove 2 were determined by the following equation. X = {(360− {α) / (360−β)} × 100
(%) Arcsin (β / 2) = W / R * Evaluation of storage groove As shown in FIG.
The maximum bulge seek H _1. The vertical wall portion, a vertical line b, c from the corners of the groove bottom surface with respect to the straight line a, obtaining the maximum bulge H _2, H ₃ in the same manner. As described above in detail in the embodiments,
ADVANTAGE OF THE INVENTION According to the manufacturing method of the one groove | channel slot which concerns on this invention, the dimensional accuracy of the storage groove of an optical fiber tape core wire is favorable, and it can manufacture at high speed and with high productivity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a design sectional view of a slot to which a method for manufacturing a single-groove slot according to the present invention is applied. FIG. 2 is an explanatory view showing steps of a method for manufacturing a single-groove slot according to the present invention. FIG. 3 is an explanatory view showing a shape of a projecting portion of a die used in the manufacturing method shown in FIG. FIG. 4 is an explanatory diagram of a sizing die used in the manufacturing method shown in FIG. FIG. 5 is a cross-sectional view of a slot obtained in Example 1 of the manufacturing method according to the present invention. FIG. 6 is an explanatory view showing a shape of a projecting portion of a die used in Embodiment 2 of the manufacturing method according to the present invention. FIG. 7 is a cross-sectional view of a slot obtained in Example 2 of the manufacturing method according to the present invention. FIG. 8 is a cross-sectional view of a slot obtained in Comparative Example 1 of the manufacturing method according to the present invention. FIG. 9 is a sectional view of a slot obtained in Comparative Example 2 of the manufacturing method according to the present invention. FIG. 10 is a sectional view of a slot obtained in Comparative Example 3 of the manufacturing method according to the present invention. FIG. 11 is an explanatory diagram of a calculation method of a slot contact ratio obtained in the example of the present invention and the comparative example. FIG. 12 is an explanatory diagram of a method for evaluating slot groove dimensions obtained in an example of the present invention and a comparative example. [Description of Signs] 1 Body 1a Bottom 1b Vertical wall 2 Storage groove 2a Groove bottom 2b Vertical wall 3 Tension member 10 Creel stand 12 Extruder 12b Dice 18 Sizing die 18e Cooling jacket

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Wataru Katsurashima 1-chome, Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Shigehiro Matsuno 2-1-1, Yabuta Nishi, Gifu-shi, Gifu No. Ube Nitto Kasei Co., Ltd. Gifu Research Institute (72) Inventor Kenji Kozuka 2-1-1 Yabuta Nishi, Gifu City, Gifu Prefecture Ube Nitto Kasei Co., Ltd. Gifu Research Laboratory (72) Inventor Masato Isobe Gifu City, Gifu Prefecture 2-1-1 Yabuta Nishi Ube Nitto Kasei Co., Ltd. Gifu Research Laboratories (56) References JP-A-5-261843 (JP, A) JP-A-1-179111 (JP, A) Jpn. (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 6/44

Claims (1)

(57) [Claims 1] A main body having a substantially circular cross section and one
A generally concave optical fiber tape with an open end
Presses the molten thermoplastic resin.
After taking out the thermoplastic resin while shaping the storage groove
Method for manufacturing a single groove slot formed by cooling
The cross section used for extruding the thermoplastic resin is substantially circular.
The cross-sectional shape of the extrusion die is formed on the outer periphery of the storage groove.
Notches on the outer periphery of the part corresponding to the thick part of the main body
The shape provided, the cross-sectional shape of the shaping and cooling sizing die,
A space is formed around the outer periphery of the notch of the extrusion die.
Characterized in that it has a circular shape and supplies cooling water to the space.
Manufacturing method of a single groove slot.