JPS6366506A - Method and apparatus for producing protective pipe for optical fiber communication cable - Google Patents

Abstract

PURPOSE:To improve workability by incorporating plural pieces of small- diameter corrugated tubes into a corrugated sleeve pipe while moving the tubes at the time of forming said sleeve pipe. CONSTITUTION:Mold blocks 1b are connected like an endless chain so as to form a corrugated cavity part 1a along the axial direction. An extruder 2 is mounted with a cross head die 2a positioned coaxially with the corrugated cavity part 1a for supplying a heated and melted thermoplastic resin tube (a) in the corrugated cavity part 1a of a moving mold 1. An air supply pipe is introduced into the thermoplastic resin tube (a) supplied into the corrugated cavity part 1a through the cross die head 2a in order to form the corrugated sleeve pipe A by expanding the tube (a). A tubular mandrel 4 is extended into the corrugated cavity part 1a of the moving mold 1 through the die 2a to incorporate plural pieces of the small-diameter corrugated tubes B into which guide wires (b) are preliminarily inserted into the corrugated sleeve pipe A while moving the same. An air stopper 4a facing the mold blocks 1b is mounted on the outside wall surface thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for manufacturing a protective tube for an optical fiber communication cable.

[Conventional technology]

This type of protective tube for optical fiber communication cables is
Generally, the optical fiber cable is directly encased in a plurality of long corrugated small-diameter tubes, which are encased in a relatively large-diameter corrugated mantle tube, but these protective tubes are molded. It was formed by inserting multiple pieces of corrugated small-bore tube into a corrugated mantle tube.

[Problem that the invention seeks to solve]

However, it is difficult to insert a corrugated small-diameter pipe made of a long piece similar to the corrugated mantle pipe into a corrugated mantle pipe made of a long piece with a length of several hundred meters or even several thousand meters. If the tip or corrugated portion of the tube comes into contact with the corrugated portion of the mantle,
In addition, these bending causes extremely high frictional resistance, making the molding operation extremely complicated.

[Means to solve the problem]

This invention was invented to solve the above-mentioned drawbacks of the conventional products, and includes a pair of movable molds formed by connecting mold blocks in an endless chain shape to form a corrugated cavity along the axial direction, and An extruder equipped with a crosshead die located coaxially with the corrugated cavity to supply a heat-meltable thermoplastic resin tube to the corrugated cavity of the mold, and a thermoplastic resin tube supplied to the corrugated cavity. An air supply tube is introduced into the thermoplastic resin tube through a crosshead die to inflate it and form a corrugated jacket tube, and a plurality of corrugated small diameter tubes are prepared by inserting guide cotton into the tubes in advance. A device consisting of a tubular mandrel that extends into a movable corrugated cavity through a crosshead die and is fitted with an air stopper facing the mold block on its outer wall surface so as to be incorporated while being transferred into a corrugated jacket tube. The above problem was solved by molding using the same method.

[Effect]

Since the present invention has the above-mentioned configuration, the heat-melting thermoplastic resin tube discharged from the crosshead die of the extruder is fed into the corrugated cavities of a pair of movable mold blocks connected in an endless chain. , while expanding the thermoplastic resin tube so as to press it against the inner wall surface of the endless chain of the mold block with pressurized air ejected from an air supply pipe introduced into the thermoplastic resin tube to form a corrugated mantle tube; A plurality of corrugated small-diameter tubes, each of which is made by previously inserting a guide wire into the tube to guide the optical fiber into the tube by tying and pulling one end of the optical fiber, are transferred through a crosshead die into a movable corrugated mantle. It is formed by incorporating it while keeping it in place.

〔Example〕

Embodiments of this invention shown in the drawings will be described below. FIG. 1 is an explanatory view showing the manufacturing process of this invention, and FIGS. 2 and 3 are partially enlarged sectional views of FIG. 1 is a pair of movable molds, which are formed by connecting mold blocks 1b in an endless chain to form a corrugated cavity 1a along the axial direction; 2 is an extruder; the movable molds 1
A crosshead die 2a is installed coaxially with the corrugated cavity 1a in order to supply a thermoplastic resin tube a that can be heated and melted into the corrugated cavity 1a, and 3 is an air supply pipe, 4 is introduced into the thermoplastic resin tube a through a crosshead die 2a in order to expand the thermoplastic resin tube a supplied to the corrugated cavity 1a and form the corrugated outer tube A. A plurality of corrugated small-diameter tubes B, which are tubular mandrels with guiding wires inserted into the tubes in advance, are transferred into the corrugated outer tube A and incorporated therein through the crosshead die 2a of the movable mold 1. An air stopper 48 extending into the corrugated cavity la and facing the mold block 1b is attached to its outer wall surface.

The meltable thermoplastic resin tube a discharged from the crosshead die 2a of the extruder 2 is connected to a movable mold 10 with a corrugated cavity part l.
The air supply pipe 3 is introduced into the thermoplastic resin tube a, and the thermoplastic resin tube a is expanded with pressurized air jetted from the air outlet 3a, thereby removing the heat in the softening state. The plastic resin tube a is pressed against the inner wall surface of the corrugated cavity 1a to form the corrugated mantle tube A, while the plurality of corrugated small diameter tubes B being passed through the crosshead die 2a are passed through the movable mold 1. The corrugated cavity part la
A corrugated mandrel A via a tubular mandrel 4 extending into the corrugated mandrel A.
transferred within. The tip of the tubular mandrel 4 extends into the corrugated cavity la to a position where the thermoplastic resin tube a is cooled to a temperature at which the thermoplastic resin tube a and the corrugated small-diameter tube B are not thermally bonded. As a result, a plurality of corrugated small-diameter tubes B are housed within the corrugated outer tube A. An air stopper 4a is provided near the tip of the tubular mandrel 4 to maintain the air ejected from the air outlet 3a of the air supply pipe 3 at a pressure sufficient to expand the molten thermoplastic resin tube a. The air supply pipe 3 is connected to a tubular mandrel 4.
The air outlet 3a is installed in the outer peripheral surface of the tubular mandrel 4 in a ring shape.

〔Effect of the invention〕

As is clear from the above, the present invention allows a plurality of small-diameter corrugated tubes to be transferred and incorporated into the corrugated jacket tube during molding of the corrugated jacket tube, so that the corrugation of the corrugated jacket tube as seen in the past can be avoided. Work efficiency has been significantly improved by eliminating the need for complicated work such as inserting small-diameter pipes.
Furthermore, since the guide wire is inserted into the corrugated small-diameter pipe in advance, it is possible to easily insert the optical fiber by simply tying one end of the optical fiber to the guide wire and pulling it, thereby improving workability.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the manufacturing process of the present invention, FIGS. 2 and 3 are partially enlarged sectional views of FIG. 1, and FIG. 4 is a perspective view of the same protection tube. 1-1 mobile type 2-1 extruder 3-1 air supply pipe 4-1 tubular mandrel la-1 corrugated cavity 1b--mold block 2a--crosshead die 3a--1 air spout 4a--1 air outlet Bar A - One corrugated mantle tube B - One corrugated small diameter tube a - One thermoplastic resin tube

Claims (2)

[Claims] (1) A heat-melted thermoplastic resin tube discharged from the crosshead die of an extruder is supplied into the corrugated cavity of a pair of movable mold blocks connected in an endless chain, and expanded with air. A corrugated small-diameter tube is formed by forming a corrugated jacket tube while moving the tube, and inserting a guide wire into the corrugated tube in advance through a tubular mandrel extending from a crosshead die into the corrugated cavity of the movable type. A method for manufacturing a protective tube for optical fiber communication cables, characterized in that a plurality of cables are built in while being transferred. (2) A pair of movable molds formed by connecting mold blocks in an endless chain to form a corrugated cavity along the axial direction, and a thermoplastic resin tube that can be heated and melted into the movable mold's corrugated cavity. an extruder equipped with a crosshead die located coaxially with the corrugated cavity; The air supply tube introduced into the thermoplastic resin tube and a plurality of corrugated small diameter tubes formed by inserting a guide wire into the tubes are transferred into the corrugated outer tube and moved through a crosshead die to be incorporated therein. 1. A manufacturing device for a protection tube for an optical fiber communication cable, comprising a tubular mandrel extending into a molded corrugated cavity and having an air stopper attached to its outer wall surface facing a mold block.