JPH06311624A - Manufacture of linear member pressure feeding pipe - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a pressure feeding pipe, provided with a spiral groove in the inner face thereof in order to increase the pressure feeding distance of linear member, easily without requiring any special attachment or mechanism. CONSTITUTION:A molten plastic material is extruded by an uniaxial screw extruder 10 and passed directly through a pipe metal mold 20 having a straight head die 23 to be molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pipe for feeding a filamentous body. In particular, the present invention relates to a method of manufacturing a pressure-feeding pipe having a spiral groove formed on the inner surface thereof for transporting and laying a communication filamentous body such as an optical fiber by fluid pressure.

[0002]

2. Description of the Related Art It is not uncommon for an extension or replacement of optical fiber or other communication filaments to be required after they have been laid on a structure or the like. However, it is not easy to lay the striatum itself each time. Therefore, a technique is used in which a pipe capable of drawing the filamentous body is previously laid in the structure. This pipe has an inner diameter such that the filament can be inserted therein, and is made of synthetic resin such as polyethylene so as not to be damaged. To insert the wire for communication into this pipe, a pressure-feeding method generally called "wind-blowing method" is adopted. In this method, while feeding the filamentous body to be inserted into a pipe by a roller or the like, a compressed gas is blown into the gap and put on the air flow to propel the filamentous body. According to such a construction method, an excessive tension is not applied to a part of the communication linear member such as the optical fiber. Thus, long distance delivery is possible without damage during insertion. However, even with such a windsock construction method, since considerable friction occurs between the inserted linear body and the pipe inner wall, there is a limit to the delivery distance, and even if it is a straight distance, if it is too long, it will reach the pipe outlet. Delivery becomes difficult. Further, when the pipe is bent and installed, this insertion resistance increases significantly according to the curvature, and the deliverable distance becomes short.

As one means for solving this problem, there has been proposed a method of providing a continuous projection in a spiral shape in the longitudinal direction on the inner surface of the pumping pipe (for example, Japanese Patent Laid-Open No. 4-131803). Gazette). In such a pipe with spiral protrusions, the air that is press-fitted advances in such a manner that it swirls in the longitudinal direction, so the linear body easily travels in the center of the pipe, and the contact area with the inner surface of the pipe also It is said that the frictional resistance is reduced and the pumping distance is extended.

[0004]

However, the above-mentioned pressure-feeding pipe has a manufacturing problem. That is, the above-mentioned pipe is generally manufactured from a plastic material by an extrusion molding method.To provide a continuous spiral projection on the inner surface of the pipe, a mandrel having a recess corresponding to the projection is formed on the mouthpiece of the extruder. The mandrel must be mounted and rotated at a constant speed during extrusion, relative to the pipe being formed. Providing a mouthpiece having such a special mechanism is extremely difficult and, if possible, is extremely expensive. Further, the same effect can be expected in a pipe in which a spiral groove is formed on the inner surface instead of the projection. To manufacture this, without using a molding device having a special mouthpiece similar to the above, for example, a metal rod having radial projections heated to the melting temperature of the resin is inserted into an ordinary pipe, A method is used in which the metal rod is pulled out while rotating while the protrusion is pressed against the inner surface of the pipe.
However, in this case, if the pipe becomes long, it cannot be manufactured.

The present invention has been made to solve such problems. Therefore, the purpose is to provide a simple method capable of producing a pressure-feeding pipe having a spiral groove formed on the inner surface thereof in order to improve the pressure-feeding distance of the filamentous body without requiring any special equipment or mechanism. To provide.

[0006]

The object of the present invention is to extrude a molten plastic material from a single-screw extruder and then directly form the molten material through a pipe die having a straight head die. This can be solved by providing a method for manufacturing a pipe for feeding a striatum.

Here, the single-screw extruder is an extruder in which one extruding screw having a rotating shaft coaxial with the barrel is provided inside a cylindrical barrel whose temperature can be adjusted. Generally, a single-screw type or a multi-screw type is used as a screw extruder for plastics, but a single-screw type is used when carrying out the production method of the present invention. The straight head die is a mold member having a cylindrical resin gap concentric with the screw rotating shaft of the extruder. As a pipe mold generally used in combination with a screw extruder for plastics, various types having a mold member such as a straight head die, a crosshead die, and an offset die are known. A straight head die type is used when carrying out the manufacturing method. When extruding an ordinary pipe by a conventional method, a screen and a breaker plate are inserted between the screw extruder and the pipe mold in order to assist the kneading of the molten material and remove the foreign matter. There is. However, in the device used in the manufacturing method of the present invention,
The screen and breaker plate are removed. That is, the melt extruded from the screw extruder directly,
It is sent to a pipe mold having a straight head die and molded into a pipe.

[0008]

The manufacturing method of the present invention is that a molten plastic material is extruded from a single-screw extruder, and then the molten material is directly passed through a pipe mold having a straight head die to be molded. According to this manufacturing method,
The plastic material is melted in the barrel of the screw extruder, kneaded, and directly extruded toward the pipe mold. At this time, since the resin flow advancing in the gap between the barrel and the screw has viscoelasticity and is given a rotational motion, it directly contacts the mandrel of the pipe mold (without being blocked by the breaker plate etc.). Then, the rotational movement is blocked here, and as a result, the resin flow is twisted. Such a twist of the resin flow passes through a straight head die and is cooled and solidified to form a spiral streak,
It will remain on the inner surface of the molded pipe. That is,
A pumping pipe having a spiral groove formed on its inner surface is manufactured. Here, the pitch of the screw, the groove depth, the rotation speed, and the temperature of the barrel are closely related to the formation of the inner surface groove of the pipe to be manufactured and its shape and depth. These are empirically determined to produce a pipe having the desired internal groove.

In the linear body pressure-feeding pipe manufactured by the manufacturing method of the present invention, when gas is pressed in when the communication linear body is laid inside the pipe, the air flow advances so as to swirl in the longitudinal direction. , The inserted linear body is pressed evenly from the surroundings to run in the center of the pipe, and even if it comes into contact with the inner surface of the pipe, the contact area is small, so the friction resistance is small and the pumping distance is remarkable. Be extended.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows the apparatus used in the examples. In FIG. 1, 10 is a screw extruder and 20 is a pipe mold. The screw extruder 10 is roughly the raw material hopper 1.
1, a barrel 12 whose temperature is adjusted, and a screw 13 having a rotation axis X coaxial with the barrel 12.
The pipe die 20 has a straight head die 23 formed of a die ring 21 and a mandrel 22. The gap between the die ring 21 and the mandrel 22 forms a resin gap 24 that is concentric with the rotation axis X of the screw 13. This resin gap is tapered.
The die ring 21 is adjusted to an appropriate temperature from the outside.

Next, a method of manufacturing a linear body pressure feeding pipe using the apparatus shown in FIG. 1 will be described. A screw 13 having an appropriate pitch and groove depth is mounted in the barrel 12 and rotated at an appropriate rotation speed. Also, the temperature of the barrel 12 is adjusted to an appropriate temperature. These operating conditions are empirically determined to obtain the pipe with the desired internal groove.

Polyethylene pellets, for example, are put into the hopper 11. The resin material is melted in the barrel 12, is kneaded, and is extruded toward the pipe die 20. Then, the extruded resin flow is directly sent to the pipe mold 20 to be molded into a pipe, and a spiral groove is formed on the inner surface thereof. The pitch of this groove can be easily controlled by adjusting the extrusion amount and the take-up speed. At this time, spiral streaks are once formed on the outer surface of the pipe, but they are smoothed by being pressed against the die ring 21 that is temperature-controlled and tapered.
Therefore, no spiral streak is found on the outer surface of the pipe taken off.

According to the above-mentioned embodiment, the spiral groove is formed on the inner surface and the outer surface is smooth only by removing the screen and the breaker plate from the commonly used pipe forming apparatus and adjusting the operation conditions. A pressure-feeding pipe was obtained.

[0014]

EFFECT OF THE INVENTION The manufacturing method of the linear pressure-feeding pipe of the present invention is as follows.
The molten plastic material is extruded from a single-screw extruder, and then this molten material is directly molded through a pipe mold having a straight head die. There is an effect that the pressure-feeding pipe in which the spiral groove is formed can be easily manufactured without requiring a special tool or mechanism.

[Brief description of drawings]

FIG. 1 is a sectional view of a manufacturing apparatus used in an embodiment of the present invention.

[Explanation of symbols]

10 ... Single screw extruder, 12 ... Barrel, 13 ...
Screw, 20 ... Pipe mold, 23 ... Straight head die.

Continuation of the front page (72) Inventor Issei Suzuki 109-2 Shirouchi-cho, Sakura-shi, Chiba Tazama Heights 102

Claims (1)

[Claims] 1. A pipe for feeding a filamentous body characterized in that a molten plastic material is extruded from a single-screw extruder and then the molten material is directly molded through a pipe mold having a straight head die. Manufacturing method.