JPH01277808A - Production of spacer for optical communication cable - Google Patents

Abstract

PURPOSE:To obtain the spacer which is free from groove collapse by using a mouthpiece formed with plural projections spirally on the inside circumference to cover a resin on tension members and simultaneously providing plural lines of optical core housing grooves on the surface of the resin surface. CONSTITUTION:While the mouthpiece 20 formed spirally with the plural projections on the inside circumference is rotated integrally with mandrels 13, 19, the resin is extruded from the mouthpiece 20 to coat the resin on the tension members 2 and the spacer 21 is simultaneously extruded by forming plural lines of the optical core housing grooves 22 on the resin surface. Since this mouthpiece 20 is formed spirally with the plural projections in the mouthpiece 1 and part thereof, the resin flows smoothly without undue stress in the rotating direction of the mouthpiece 20 and is coated on the tension members 2. The collapse of the optical core housing grooves 22 of the extruded spacer viewed in the section of the spacer is thereby obviated and the good section is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the manufacture of optical communication cables, and particularly to a method for manufacturing a spacer having an optical core storage groove, that is, a twisted groove for storing an optical fiber on its outer periphery. It is.

[Prior Art] Generally, the structures of optical communication cables include a spacer type, a twisted type, a unit type, and the like. Among these, the spacer-type optical fiber cable has a structure in which the fiber core (optical core) is housed in a groove provided on the outer periphery of the spacer and protected from external forces, and is suitable for optical fiber cables with 12 fibers or less.

Usually, in this spacer-type optical fiber cable, in order for the optical fiber to withstand the tension during cable installation, a tensile strength member (tension member) 4 such as a steel wire is attached to the spacer 15 as shown in FIG. placed in the center. Further, the optical core storage groove 16 on the outer periphery of the spacer is formed in a spiral shape to twist the optical fibers in the cable so that excessive tension is not applied to the optical fibers when the cable is bent.

An outline of a conventional spacer manufacturing method will be explained using FIG. 8.

First, a tension member 2 is sent out from a delivery drum 1. An extruder 3 extrudes a resin such as polyethylene (PE) or polyvinyl chloride (PVC) to a crosshead 4, and a one-rotation drive device 6 passes it through a sprocket 5 to a nozzle. When the lO is rotated, the mandrel 19 (FIG. 1), which is integral with the base 10, is also rotated. Resin is extruded through the rotating base 10, and the tension member 2 is coated with the resin, forming a spacer 21 (FIG. 4). At this time, as shown in FIGS. 6 and 7, a plurality of axially straight protrusions 10a are provided in the circumferential direction on the inner periphery of the tip of one cap 10, and these protrusions 10a allow
An optical core storage groove 22 as shown in FIG. 4 is formed in the outer peripheral surface of the spacer 21 in an am-shape. The extruded spacer 21 is cooled and solidified in a cooling water tank 7, taken up by a take-up machine 8, and wound up on a take-up drum 9.

[Problems to be Solved by the Invention] However, in the conventional cap 10, as shown in FIGS. 6 and 7, the protrusion lOa provided on the inner periphery is machined straight in the axial direction. That is, although the base lO is rotating, the resin flows straight through the protrusion lOa.

For this reason, the tension member 2 at the outlet of the base lO
When the resin is covered with a rotating plate, the extruded spacer has the disadvantage that the optical core storage groove is distorted when viewed in cross section.

Furthermore, since groove collapse occurs, the take-up speed must be kept low, resulting in poor productivity.

SUMMARY OF THE INVENTION An object of the present invention is to provide a spacer manufacturing method that eliminates the drawbacks of the prior art described above and that makes it possible to obtain a spacer without groove collapse.

[Means for Solving the Problems] The method of manufacturing a spacer for an optical communication cable of the present invention rotates a cap having a plurality of spiral projections formed on the inner periphery together with a mandrel, and presses a resin from this cap. This is a method in which the tension member is coated with resin, a plurality of optical core storage grooves are formed on the resin surface, the spacer is pushed out, the spacer is cooled, and the spacer is removed.

[Function] Since the protrusion of the so-called extrusion land portion of the die is formed in a spiral shape, the spacer extruded from this has a good spacer cross section without groove collapse, and the product quality is greatly improved.

[Example] Examples of the present invention will be described below.

The extrusion method and procedure are almost the same as the conventional one, except that the conventional die 10 is replaced with a die 20. shown in FIGS. 2 and 3. That is, it uses a cap 20 in which a plurality of protrusions 20a on the cap land are formed in a spiral shape. This protrusion 20a is precisely machined into a spiral shape using an electric discharge machine.

By using this cap 20, the resin flows effortlessly and smoothly in the direction of rotation of the cap 20, and is coated on the tension member 2.

FIG. 1 shows a section of the extrusion head. First, resin is extruded by the extrusion screw 11 of the extruder 3, flows into the cross rad 4, passes through the resin flow path 14, and forms an annular band. The flow reaches the base 20.

The tension member 2 enters the crosshead 2 through the mandrel 13, passes through the mandrel 19 and the cap 20, and is taken off to the left in FIG. 1 by the take-off machine 8.

This tension member 2 is coated with resin at the tip of the base 20 . In this case, the rotary cap holder 1 is rotatably supported on the flange 15 by a bearing 16.
8 is connected to a motor of a rotation drive device 7 via a sprocket 5, and by rotating the motor, the rotary cap holder 18 and the cap 20 rotate together with the mandrel 19.

Therefore, the spacer 21 extruded from the base lO is extruded in the form of a tension member-containing spacer having a helical optical core storage groove 22.

Note that 12 is a cap fixing bolt, and 17 is a rotating gasket.

This cap 20 has a plurality of protrusions 20a on its cap land.
Since the resin is formed in a spiral shape, the resin flows easily and smoothly in the direction of rotation of the base 20 and is coated on the tension member 2. Therefore, as shown in FIG. 4, the optical core storage groove 22 of the extruded spacer has no groove collapse when viewed in cross section of the spacer, and an extremely good cross section can be obtained.

In the case of this embodiment, the spiral angle of the base 20 is as follows with respect to the spacer diameter of 10 mm and the groove pitch of 375 ta.
The range of 2.8° to 3.28° was most appropriate.

At angles larger than this or smaller than this, groove collapse occurred in this embodiment.

In the above embodiment, the protrusion 20a of the cap 20 is provided in the radial direction from the center of the cap, but the shape is not limited to this.As shown in FIG. The groove can be formed as an angled protrusion, and the one provided with the angled protrusion 20a is also very effective in preventing the occurrence of groove collapse. Note that the angle (θ) is proportional to the groove pitch.

[Effects of the Invention] The uninvented object extrudes resin through a die in which the protrusion of the extrusion land portion is formed in a spiral shape, and obtains a good spacer cross section without groove collapse, so the spacer as an extruded product is improved. It is possible to significantly improve quality accuracy and, by extension, the quality of optical communication cables.

Furthermore, since groove collapse does not occur, the take-up speed can be increased, resulting in a significant improvement in productivity.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a head assembly for extruding a spacer, FIG. 2 is a vertical cross-sectional view of a die in an embodiment of the present invention, FIG. 3 is a cross-sectional view thereof, and FIG. 4 is a cross-sectional view of a head assembly for extruding a spacer. FIG. 5 is a cross-sectional view of the spacer, and FIG. 6 is a diagram showing another specific example of the cap.
The figure is a vertical cross-sectional view of a conventional cap, FIG. 7 is a cross-sectional view thereof, and FIG.
The figure is a block diagram showing a conventional spacer manufacturing line device. In the figure, l is the delivery drum, 2 is the tension member,
3 is an extruder, 4 is a crosshead, 5 is a sprocket, 6
1 is a rotary drive device, 7 is a cooling water tank, 8 is a take-up machine, 9 is a winding drum, 11 is an extrusion screw, 12 is a base fixing bolt, 13 is a mandrel, 14 is a resin flow path, 16 is a bearing, 1
7 is a rotating gasket, 18 is a rotating base holder, 19 is a core metal, zO is a base, 20a is a protrusion, 21 is a spacer, and 22 is an optical core storage groove. 4: RIO SHENOTO 5X Sprocket) 3, 19: 4 door 8; Rotary cap holder ゛20゛Base 2I Varnish cover-゛22/Optical core throat J groove

Claims (1)

[Claims] 1. By rotating a cap with multiple protrusions formed in a spiral shape on the inner periphery together with the core metal and extruding resin from the cap, the tension member is coated with resin and at the same time multiple stripes of light are formed on the resin surface. A method for manufacturing a spacer for an optical communication cable, characterized by forming a core storage groove, extruding the spacer, cooling it, and taking it off.