JPH041326B2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> The present invention relates to a method and apparatus for manufacturing an optical fiber supporting spacer used when forming an optical fiber for optical communication into a form of a cable that can be laid. In particular, the present invention relates to a spacer that can improve the shape accuracy of the spacer.

<<Prior art>> This type of spacer is made by using a single steel wire, twisted steel wire, etc. as a tensile strength wire, coating the outer periphery of the spacer with thermoplastic resin, and forming a plurality of spirals continuous in the longitudinal direction on the outer periphery of the spacer. Types with grooves are known, and their manufacturing method involves inserting a tensile strength wire into a crosshead die and melting and extruding a thermoplastic resin from the die while rotating a die of various shapes to coat the wire. , cooling solidification methods, etc. are known.

By the way, in this type of spacer, the forming precision of the spiral groove deteriorates due to variations in extrusion speed and melting temperature, and this tendency is particularly strong in the case of crystalline resin. However, this tendency became apparent when the depth of the spiral groove was large, when the thickness of the rib portion between the grooves was thin, and when the outer diameter of the tensile strength line was smaller than the root diameter of the spiral groove.

The causes of deterioration in shape accuracy are (a) the shrinkage force of the spacer resin when it cools and solidifies, especially the shrinkage force accompanying crystallization, and (b) the viscoelastic force of the thermoplastic resin that acts in the opposite direction to the rotational force of the die. considered as the main one.

In particular, cause (b) greatly affects shape accuracy, and even if the cooling conditions are strict and cause (a) is removed, the ribs between the spiral grooves will solidify with an inclination to the opposite side of the rotation direction. Ru.

Therefore, in order to solve this problem, for example, Japanese Patent Laid-Open No. 58-105110 or Japanese Patent Laid-Open No. 58-126504
A manufacturing method and apparatus such as those found in the publication are provided.

<<Problems to be Solved by the Invention>> The manufacturing methods and devices disclosed in the above publications all shape the spacer by cutting, and therefore require cutting dies corresponding to various cross sections of the spacer. Since the machining accuracy of the die directly affects the spacer shape accuracy, a high-precision cutting die must be used, resulting in an increase in costs.

Furthermore, in the manufacturing method disclosed in JP-A-58-105110, the hardened and deformed spacer is sized using a die or the like, so if the degree of deformation is large,
Sizing becomes difficult.

On the other hand, in the processing device disclosed in JP-A No. 58-126504, a pair of dies are installed in a heat-retaining tank, and reprocessing is performed while maintaining the heat-retaining state. However, it is troublesome to control and maintain the heat-retaining state, and Although the process is different, it is difficult to cut an uncured resin spacer, and if it is cut forcefully, there is a risk that deformation will be promoted. The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a method and apparatus that can obtain a spacer with a relatively simple structure and good shape accuracy.

<<Means for Solving the Problems>> In order to achieve the above object, the present invention provides a method for manufacturing an optical fiber supporting spacer in which the outer periphery of a tensile strength wire is coated with a resin having a spiral groove. The method invention is characterized by pressing one side of the spiral groove by mechanical means in the same direction as the rotation direction of the rotary die immediately after extrusion from the resin, and then cooling and solidifying the resin. a support means attached to a rotary die forming a resin coating with grooves; a pin holder coaxial with the rotary die and attached to the support means;
The device invention is characterized in that it has a plurality of shaping pins held by the pin holder so as to be movable forward and backward within the spiral groove, and either the pin holder or the shaping pins are rotatable.

<<Operation>> According to the manufacturing method with the above configuration, the soft resin whose surface has been slightly cooled from the molten state is pressed in the same direction as the rotational direction and cooled and solidified, so that the spacer produced by the viscoelasticity of the thermoplastic resin deformation is prevented.

On the other hand, the amount of spacer deformation due to viscoelasticity depends on the resin composition, the diameter and type of tensile strength wire, the number and depth of spiral grooves,
Although it varies depending on the pitch, etc., in the manufacturing apparatus of the present invention, the shaping pin moves forward and backward into the spiral groove, and the holder or itself is rotatable, so it can easily respond to variations in the amount of deformation.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 4 show an embodiment of the method and apparatus for manufacturing an optical fiber supporting spacer according to the present invention.

FIG. 1 is an explanatory diagram of the installation position of the device, and the device 10 is located between a rotary die 14 attached to a thermoplastic resin extruder 12 and a cooling tank 16, and is located at the same location as the rotary die 14. It is installed directly below the axis.

The rotary die 14 is supplied with molten thermoplastic resin from the extruder 12, and the tensile strength wire 1 is passed through the rotary die 14 from above.
8 is supplied, and by rotating the rotary die 14 by an appropriate means, a spacer 20 having a resin coating having a spiral groove on the outer periphery of the tensile strength wire 18 is continuously produced, and the resin is cooled in the cooling tank 16. The solidified spacers 20 are sequentially pulled vertically downward.

Details of the device 10 described above are shown in FIG.

The device 10 includes a pair of vertically suspended support shafts 22, 22 whose one end is fitted onto the lower surface of the rotary die 14, and a mounting bolt 24 that is tightened between the shafts 22 at the other end of the support shaft 22. A fixed disk-shaped support plate 26 and a hollow cylindrical support tube 3 fixed to the upper surface of the support plate 26 with fastening bolts 28.
The support plate 26 has a through hole 32 having substantially the same shape as the inner diameter of the support tube 30.

A flange-shaped pin holder 36 is rotatably held inside the support tube 30 via a bearing 34, and the pin holder 36 is locked in any position by a butterfly bolt 38 inserted through the support tube 30. be done.

As shown in FIG. 3, a plurality of shaping pins 40, 40 are mounted on the flange surface of the pin holder 36 in a substantially horizontal state at predetermined intervals in the circumferential direction.
The number of pins 40 corresponds to the number of spiral grooves of the spacer 20, and the center of each pin 40 and the central axis of the rotary die 14 are aligned.

As an example of the shaping pin 40 is shown in FIG. The chip 42 is attached by inserting a mounting screw 46 into the spacer 20, and by adjusting the positional relationship between the elongated hole 44 and the mounting screw 46, the amount by which the chip 42 moves forward and backward within the spiral groove of the spacer 20 can be varied.

Although the shape of the tip 42 differs depending on the form of the spiral groove, at least the diameter of the tip 42 should be smaller than the width of the spiral groove of the spacer 20, and
The outer diameter of the tip almost corresponds to the root diameter of the spiral groove, and the curved surface is slightly smaller than the root diameter.

Next, a method for manufacturing the spacer 20 will be explained.

First, the rotation of the rotary die 14 is stopped, and the extrudate in which not the spiral grooves but the linear grooves are formed is taken off.

Then, in this state, the shaping pins 40 are aligned. For example, one side of the tip 42 of each shaping pin 40 is brought into contact with one side of the linear groove,
In addition, attach the pin 40 to the holder 3 using the mounting screw 46 so that its tip abuts the valley of the groove.
Fixed at 6.

In this case, it is easier to do this with a straight groove than to do so while rotating the rotary die 14.
This method is preferred.

After the shaping pins 40 have been set, the rotary die 14 is driven to rotate.

At this time, the butterfly bolt 38 is not tightened and the pin holder 36 is left in a free state.
is rotated in synchronization with the rotating die 14.

Then, while observing the shape of the cooled and solidified spacer 20, the holder 36 is rotated in the same direction as the rotating direction of the rotary die 14 to create a positive phase difference, that is, an advanced phase, between the shaping pin 40 and the spiral groove. Set. As a result, the side surface of the shaping pin 40 comes into contact with one side of the spiral groove of the spacer 20, and the molten resin in this area is gradually pressed toward the opposite side of the pin 40. After adjusting the phase difference and obtaining a good molding condition, attach the pin holder 36 to the butterfly bolt 38.
It is held and fixed to the support tube 30.

Since the support tube 30 is connected to the rotary die 14 via the support plate 26 and the support shaft 22, the shaping pin 40 is connected to the rotary die 14 while maintaining the phase difference set between the shaping pin 40 and the helical groove. The spacer 20 is continuously produced while properly correcting the deformation caused by the viscoelasticity of the spiral groove of the spacer 20.

Note that the setting of the shaping pin 40 is not limited to the method described above; for example, the angle and direction of the inclination of the ribs between the spiral grooves are predicted in advance, and a phase difference is set in the opposite direction to set the shaping pin 40. They may also be rotated synchronously.

FIG. 5 shows another embodiment of the device 10 of the present invention, and only its features will be described.

In this embodiment, the pin holder 36 is fixed,
Each shaping pin 40 attached to the holder 36 is rotatably adjustable.

That is, a recess 48 in which the shaping pin 36 is accommodated is provided on the upper surface of the pin holder 36, and a pair of adjusting screws 50, 50 are screwed into opposing positions of the recess 48, and the amount of protrusion of the adjusting screw 50 is adjusted depending on the amount of protrusion. Accordingly, the angle θ of each shaping pin 40 is adjusted.

Even with such a configuration, the spiral groove of the spacer 20 can be corrected by the method described above, and the phase difference between each shaping pin holder 36 and the spiral groove can be set individually, so that the spiral groove of the spacer 20 due to viscoelasticity can be adjusted. This can easily handle cases where the amount of deformation of the grooves differs from groove to groove.

<<Effects of the Invention>> As described above in detail in the Examples, according to the method and apparatus for manufacturing an optical fiber supporting spacer according to the present invention, cutting is performed after the resin has hardened or in a heat-retaining state. Therefore, a spacer with high molding accuracy can be obtained.

In addition, the configuration of the device is not only relatively simple, but also
It has a wide degree of freedom that allows it to easily follow fluctuations in the degree of deterioration in shape accuracy due to viscoelasticity, which varies depending on the resin composition used and the shape of the spiral groove.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the installed state of the device of the present invention, Figure 2
3 is a top view of the pin holder, FIG. 4 is an enlarged view of the shaping pin, and FIG. 5 is an enlarged view of the main part of another embodiment. 10...control device, 12...extruder, 14...
Rotating die, 16... Cooling tank, 18... Tensile strength wire,
20... Spacer, 22... Shaft, 24...
Mounting bolt, 26... Support plate, 28... Fastening bolt, 30... Support cylinder, 32... Through hole, 34... Bearing, 36... Pin holder, 38... Butterfly bolt, 40... Shaping pin, 42...chip, 44
...Elongated hole, 46...Mounting screw, 48...Recess.

Claims (1)

[Claims] 1. In a method for manufacturing an optical fiber supporting spacer in which a resin coating having a spiral groove on the outer periphery of a tensile strength line is applied, immediately after extruding molten resin from a rotary die, the direction of rotation of the rotary die is determined by mechanical means. A method for manufacturing an optical fiber supporting spacer, which comprises pressing one side of a spiral groove in the same direction as the above, and then cooling and solidifying the resin. 2. The method of manufacturing an optical fiber supporting spacer according to claim 1, wherein the mechanical means includes a shaping pin that rotates synchronously with the rotating die and enters the spiral groove. 3. A support means attached to a rotary die that is rotationally driven and forms a resin coating with a spiral groove on the outer periphery of the tensile strength line, and a pin holder coaxial with the rotary die and attached to the support means. , a plurality of shaping pins held by the pin holder so as to be movable in the spiral groove, and either the pin holder or the shaping pins are rotatable. Supporting spacer manufacturing equipment.