JP3104926B2 - Manufacturing method of single groove spiral slot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a slot for holding an optical fiber having a high-accuracy storage groove suitable for storing and holding an optical fiber tape or the like. The present invention relates to a method of manufacturing a twisted helical slot that rotates around a long axis.

[0002]

2. Description of the Related Art An optical fiber cable is currently used as a cable for subscribers of public communication, and is expected to be used as a cable connected to each home in the future. It is said that an ultrahigh-density optical fiber cable having a much higher density than the current one is required for use in such applications.

[0003] In such an ultra-high-density optical fiber cable, it is desirable to use a multi-core tape core wire arranged at a high density, and a cable is formed using this type of tape core wire. In this case, it is desirable to use a slot in which the cross-sectional area A of the concave groove accommodating the groove and the cross-sectional area B of the slot main body satisfy A / (A + B)> 30%. At this time, the shape of the slot groove is optimally rectangular (hereinafter referred to as square groove).

Further, if a spiral twist is given to the groove in which the optical fiber is housed, the tension applied to the optical fiber when the slot is bent is made uniform, so that there is an advantage that the transmission loss is small. Occurs. Such slots are used in a state of being densely twisted around a separately formed tension member, or are used alone as an optical cable because the grooves are spiral.

As a method of manufacturing such a slot,
Extrusion molding of thermoplastic resin is generally adopted,
There were two problems described below.

[0006]

That is, the first problem is that high precision is required for the size of the square groove in which the optical fiber is housed, and that it is necessary to secure this over the entire length of the slot. That is. The second problem is that the groove is formed in a spiral shape.

[0007] In particular, in the second problem, in the conventional manufacturing method, at the time of melt extrusion, a die corresponding to a cross-sectional shape of a target slot is extruded while rotating.
A method of forming a spiral groove and then cooling and solidifying it is adopted.

However, in such a conventional manufacturing method, since the dies are rotated, the apparatus becomes complicated.
In addition, in order to extrude molten resin while rotating, it is necessary to design a die in consideration of its melt viscoelasticity,
In addition, there are restrictions on the resins that can be used in view of the heat resistance of the packing and the like of the rotating and sliding parts. Furthermore, even if molding is performed using a die designed in such a manner, the deformation of the groove shape is still complete. Problems such as being unable to be suppressed.

In this case, in particular, the ratio of the cross-sectional area occupied by the groove portion is very large, and the groove depth is 1/1 / the outer height of the slot.
In the case of slots having two or more deep grooves, it has been very difficult to obtain a stable spiral groove.

The present invention has been made in view of such conventional problems, and has as its object to solve the above-described apparatus and molding problems, and to provide high precision and high reliability. An object of the present invention is to provide a method for manufacturing a single-groove spiral slot from which a slot is obtained.

[0011]

In order to achieve the above-mentioned object, the present invention comprises a spiral member for accommodating an optical fiber tape core wire and the like, comprising a tension member and a crystalline thermoplastic resin. In the method for manufacturing a single-groove helical slot, the tension member has a shrinkage rate of 5% or less at a softening point of the thermoplastic resin, and after extruding the thermoplastic resin around the tension member, A first step of forming a molded product having a storage groove extending linearly in the longitudinal direction by cooling at a temperature lower than the melting point, and forming the molded product at a temperature equal to or higher than the softening point of the thermoplastic resin and lower than the melting point; A twisting process is performed by rotating the housing groove around and then cooling and solidifying to form the storage groove in a spiral shape.

The tension member in the present invention is
High-strength, high-modulus organic fibers (aromatic polyamide, aromatic polyester, polyamide, polyester, vinylon), inorganic fibers (glass fibers, carbon fibers, ceramic fibers, metal fibers), and their aggregates (fiber bundles, Twisted structures, braids, etc.), and FRP or FRTP filaments, thin metal wires, metal wire aggregates, etc. using the above-mentioned fibers and fiber aggregates as reinforcing fibers. A member that receives tension applied to the slot body during manufacturing, when slots are assembled into a cable, when a cable is laid, or when a cable is used.

The arrangement and configuration of the tension members in the slot are set in consideration of the tension applied to the slot body when the slot is manufactured, when the slots are assembled into a cable, when the cable is laid, and when the cable is used. Just do it.

The crystalline thermoplastic resin that can be used in the present invention is selected from various crystalline thermoplastic resins according to the performance required for the slot for supporting an optical fiber. And various polypropylenes, among which the low-temperature embrittlement temperature is −40 ° C. or less, and the flexural modulus at room temperature is 100%.
A resin of kg / mm ² or more is preferable, and high-density polyethylene, nylon 12, PBT (polyethylene butylene terephthalate) and the like are recommended.

In the present invention, the softening point of the resin is
Refers to the value measured by JIS K7207 B method.
In the first step of the present invention, the tension member is supplied to the extruder without twisting, and after extruding the crystalline thermoplastic resin into a desired cross-sectional shape around the tension member, cooling is performed at a temperature lower than the melting point. Thus, a molded product having a linear storage groove is obtained.

At this time, if necessary, a method of sizing while cooling, a method of cooling and solidifying below the softening point, and a method of sizing while cooling and solidifying below the softening point can be selected. In the second step, the molded product having the linear storage groove obtained in the first step, the softening point of the crystalline thermoplastic resin or more,
While keeping the temperature below the melting point, twisting is performed by rotating around the long axis, and then cooling and solidifying to form the storage groove in a spiral shape.

In the second step, the thermoplastic resin is heated to a temperature at least near the softening point before or during or after the twist is applied, and the twist is fixed by thermal shaping. To obtain a slot with a predetermined helical pitch. If necessary, if the groove is sized at an appropriate position in the second step of twist forming, the groove size and shape become uniform.
In order to add a twist by rotating the molded product having a linear storage groove obtained in the first step around the long axis, it is common to add a twist by a rotary take-up machine. When the step and the second step are not performed continuously, the first step is a non-twisted form that is wound around a drum, and is supplied while being rewound in the second step, or the drum is twisted. It is also possible by rewinding while rotating as described above and supplying it to a usual take-up machine.

The sizing in each of the above steps refers to contacting a solid corresponding to the shape and outer shape of the groove to make the shape uniform, and in sizing a linear groove, the sizing key is as follows: After the twist forming, a plurality of sizing pins that can rotate and follow the spiral groove are used.

[0019]

According to the method of manufacturing a single-groove spiral slot of the present invention, a molten thermoplastic resin is extruded on the outer periphery of the tension member without rotating the tension member to form a molded product having a linear storage groove. After the first step, twisting is applied in the second step to convert it into a spiral storage groove, so there is no need for a die with a complicated structure such as a rotary die used in the conventional manufacturing method, and thermoplastic resin The degree of freedom of the selection is increased, troublesome operations such as disassembly and cleaning are not required, and problems on the apparatus and molding are eliminated.

In the second step of twisting, the crystalline thermoplastic resin is heated so as to be in a softened state,
The shape of the spiral storage groove due to plastic deformation is fixed, and slots with a constant pitch are obtained.

When the production method of the present invention is employed, the crystalline thermoplastic resin undergoes thermal shrinkage due to the effect of the heating temperature. However, a tension member whose shrinkage at the softening point of the thermoplastic resin is 5% or less is used. By making the tension member and the crystalline thermoplastic resin adhere or adhere to each other, heat shrinkage can be suppressed.

Further, if a sizing process is performed in which a sizing key or the like is brought into contact with the storage groove, the dimensional accuracy of the groove is improved, and a change over time is suppressed by a heat treatment effect.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

Embodiment 1 As shown in FIG. 1, a spiral rectangular storage groove 1 is provided at the center of a circular cross section, and a total of three tension members 2 are provided on both sides and the bottom of each rectangular storage groove 1. Were manufactured by the method shown in FIG. In this manufacturing method, the target dimensions of the rectangular storage groove 1 were 3.8 mm in width and 3.5 mm in depth, and the outer diameter of the slot 3 was 6.0 mm.

In the manufacturing method shown in FIG. 2, three 1140 denier aromatic polyamide fibers (manufactured by DuPont: Kevlar 49) are prepared as tension members 2, and these are set on a clear stand 4. Set and tension each three tension members 2 with dancer roller 5 450
The tension was applied to the nipple mounted on the head portion 7 of the melt extruder 6, and the nipple was inserted into a predetermined position.

Then, on the outer periphery of the tension member 2, a die corresponding to the sectional shape of FIG.
Resin (Ube Industries, Ltd .: UBE3035U, melting point 17)
5 ° C.) in a molten state, extruded and coated, and sizing with a sizing key 9 while cooling with water in a cooling tank 8 while taking off machine 1
Molded product 1 with a straight rectangular storage groove
1 was obtained (first step).

Subsequently, the molding 11 was heated at a set temperature of a hot air generator of 200.degree. C., an inlet temperature of 140.degree.
After passing through the heat treatment furnace 12 at a speed of 1 m / min to soften by heating, it was supplied to a sizing device 14 via a rotation prevention guide 13 having a projection engaging with a groove.

The sizing device 14 is provided with a spiral housing groove 1 formed with a twist added by the rotation of the rotary take-off machine 15.
5 sets of sizing pins 16 for sizing the groove 1 while rotating by fitting into the sizing device. In the sizing device 14, the slots are cooled while the spiraling and fixing of the linear rectangular storage groove, and the sizing is performed. Is performed (second step). Next, the obtained slot 3 was wound around a drum by a rotary winder 17.

In the slot 3 obtained, the width of the spiral rectangular storage groove 1 is 3.76 to 3.83 mm, and the spiral pitch is 50.
It was 0 to 530 mm. The slots manufactured in this way are assembled into a large number, or they are used alone as optical fiber cables, but if the groove dimensions and pitch change during long-term use, transmission loss will increase. Becomes Therefore, the slots were subjected to a heat test at 100 ° C. × 1 hour. The result is shown in FIG. As is clear from the results in FIG. 3, there is almost no change in the groove size and the pitch, and there is little concern about a change with time.

Examples 2 to 4 and Comparative Examples 1 to 2 Single-groove helical slots were manufactured using the materials and manufacturing conditions shown in FIG. Each of the slots obtained in Examples 2 to 4 and Comparative Examples 1 and 2 was also subjected to a thermal test. The results obtained by the tests are also shown in FIG.

As is apparent from the results shown in FIG. 4, the crystalline thermoplastic resin constituting the slot is twisted in a temperature range from the softening point to the melting point, and then sized while being cooled. In all of the slots of Examples 2 to 4, there were almost no changes in the groove size and pitch, and the slots were not likely to change over time.

[0032] In Example 3 shown in FIG. 4, to divide the the first step and the second step, the winding in the manufacturing process shown in FIG. 2, an Dan molded product 11 at the rear of the take-up machine 10 It is manufactured by a process of winding onto a bobbin of a take-up machine and then supplying the molded product 11 to the heat treatment furnace 12 while rewinding the formed product 11 from the bobbin.

In the fourth embodiment, a single-groove helical slot is manufactured in the step shown in FIG. 3. In this manufacturing method, the first step and the second step are divided as in the third embodiment.
After winding the molded article 11 around a bobbin, the bobbin is mounted on a rotary feeder 21 and supplied to the heat treatment furnace 12 while being unwound while rotating so that the molded article 11 is twisted. The twist was fixed and wound on a bobbin via the take-up machine 10.

On the other hand, the heat shrinkage at 175 ° C. is 10%
Polyester fiber (manufactured by Teijin Limited: BHT-10)
The slot of Comparative Example 1 using (00-250-P) as the tension member 2 was a slot in which the dimensional accuracy of the groove, in particular, irregularities in the form of ripples on the inner surface of the groove, and the pitch varied.

Further, the slot of Comparative Example 2 in which twisting was performed at 130 ° C., which was equal to or lower than the softening point of the PBT, had a large pitch after the heat treatment test. It could not be used for fiber cable. In each of the above embodiments, the case where the sizing process is performed on the molded product 11 in the first step has been exemplified, but the sizing process in this step is not necessarily required.

[0036]

As described in detail above, according to the manufacturing method of the present invention, a slot having a spiral housing groove having high groove size and high precision without rotating the die part of the melt extruder. Therefore, various problems such as thermal decomposition of the resin due to the use of the rotating die can be solved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a slot to which a manufacturing method according to the present invention is applied.

FIG. 2 is an explanatory view showing an example of a manufacturing method according to the present invention in the order of steps.

FIG. 3 is an explanatory view showing a main part of another example of the manufacturing method according to the present invention.

FIG. 4 is a table showing manufacturing conditions of a manufacturing method according to the present invention together with manufacturing conditions of a comparative example.

[Explanation of symbols]

 1 Rectangular storage groove 2 Tensile wire 3 Slot

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigehiro Matsuno 2-1-1 Yabuta Nishi, Gifu City Ube Nitto Kasei Co., Ltd. Gifu Research Institute (72) Inventor Kenji Kozuka 2-1-1 Yabuta Nishi, Gifu City Ube Nitto Kasei Co., Ltd. Gifu Research Laboratories (72) Inventor Masato Isobe 2-1-1, Yabuta Nishi, Gifu City Ube Nitto Kasei Co., Ltd. Gifu Research Laboratories (56) References JP-A-58-102910 (JP, A) JP-A-58-126505 (JP, A) JP-A-63-108921 (JP, A) JP-A-62-32021 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 47/00-47/96 G02B 6/44

Claims (1)

(57) [Claims] 1. A method of manufacturing a single-groove helical slot comprising a tension member and a crystalline thermoplastic resin and having one helical groove for accommodating an optical fiber tape core wire or the like, wherein the tension member comprises: The thermoplastic resin has a shrinkage ratio at the softening point of 5% or less. After the thermoplastic resin is extruded around the tension member, it is cooled at a temperature lower than the melting point and linearly extends in the longitudinal direction. The first step of forming a molded article having a storage groove, after applying the twist by rotating the molded article around the long axis in a temperature range of the softening point or more of the thermoplastic resin and less than the melting point,
A second step of cooling and solidifying to form the storage groove in a spiral shape.