JPH01166012A - Grooved spacer and its manufacture - Google Patents

Abstract

PURPOSE:To improve the close adhesive strength between plastic layers by forming a ruggedness on the contact surfaces between plastic layers. CONSTITUTION:Two plastic layers 2 and 3 are formed around a central high- tensile body 1, and a ruggedness 2a is formed on the contact surface between plastic layers. One plastic inner layer 2 is extruded and coated around the center high-tensile body 1, and the outer layer 3 having grooves 4 in the lengthwise direction is extruded and coated around this inner layer 2. The inner layer 2 is extruded and formed at such low temperature that the ruggedness 2a is formed on its outer peripheral surface. Consequently, the outer plastic layer 3 is formed after the ruggedness 2a is formed on the outer peripheral surface of the inner plastic layer 2. Thus, the inner peripheral surface of the outer plastic layer 3 is made rugged in accordance with the ruggedness 2a, and front and parts of projections of the ruggedness are easy to fuse and they are melt-fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a grooved spacer used for optical fiber cables, copper cables, etc., and a method for manufacturing the same.

<Prior Art> FIG. 4 shows a cross-sectional view of an example of a conventional grooved spacer for storing optical fibers. In the drawings, 01 is a central tensile strength member made of a metal wire such as copper, iron, or steel, or a single wire or a stranded wire of fiber reinforced plastic (FRP), and the grooved spacer B has the tensile strength on the outer periphery of the central tensile strength member 01. After extrusion coating the inner layer 02 made of an adhesive polyolefin resin with good adhesion to the body 01, an inexpensive high-density polyethylene (H
The outer layer 03 of DPE) is extrusion coated. At this time, the outer circumferential surfaces of the inner layer 02 and the outer layer 03 are smooth, and the outer layer 03 has five spiral grooves 04 formed in the longitudinal direction to accommodate the optical fibers during extrusion coating. The spiral groove 04 has a true spiral shape twisted in one direction, but some grooves have a sine curve shape in which the twist direction is reversed at regular intervals.

As shown in Part B, conventionally, a two-layer grooved spacer has been used because it can be made at low cost while maintaining good adhesion to the central tensile strength member 01.

<Problems to be Solved by the Invention> However, as described above, the outer periphery of the central tensile strength member 01 is coated with the inner layer 02 with good adhesiveness by extrusion, and the outer layer 03 with the spiral grooves 04 formed thereon is further coated by extrusion. In the conventional grooved spacer made of
It had the disadvantage that the adhesion between both layers was weak.

SUMMARY OF THE INVENTION In view of these problems, an object of the present invention is to provide a grooved spacer with improved adhesion between plastic layers and a method for manufacturing the same.

<Means for Solving the Problems> A grooved spacer according to the present invention that achieves the above object is formed by forming at least two plastic layers around a central tensile strength member, and extending longitudinally on the surface of the outermost layer. A grooved spacer having grooves is characterized in that unevenness is formed on the contact surfaces of the plastic layers, and the manufacturing method thereof includes extrusion coating at least one plastic inner layer around the central tensile strength member. Further, in the method of manufacturing a grooved spacer, the outermost layer having grooves extending in the longitudinal direction around the outermost layer is coated by extrusion, characterized in that each of the inner layers is extrusion molded at a low temperature at which irregularities are formed on the outer circumferential surface thereof.

Effect〉 When forming a plastic layer on a plastic layer,
When an outer plastic layer is formed after forming irregularities on the outer circumferential surface of the inner plastic layer, the inner circumferential surface of this outer plastic layer becomes uneven corresponding to the above-mentioned unevenness, and the tips of the convex parts of the above-mentioned unevenness are formed. becomes easier to melt and be fused.

Embodiments Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of the grooved spacer of this embodiment. As shown in the figure, this grooved spacer is made by extrusion coating an inner layer 2 on the outer periphery of a central tensile strength member 1, and an outer layer 3 having a spiral groove 4 thereon. is provided with unevenness 2a. This unevenness 2a may be caused by melt fracture as shown later, or after molding,
For example, it may be formed by knurling. As a matter of course, the inner peripheral surface of the outer layer 3 extrusion coated on the inner layer 2 having such an unevenness 2a has unevenness corresponding to the unevenness 2a. Note that the inner layer 2 is the tensile strength member 1
It is preferable to use a plastic that has good adhesion to the outer layer 3 and is as inexpensive as possible.

Next, a preferred manufacturing example of such a grooved spacer will be described.

FIG. 2 schematically shows the extraction apparatus used in this example. As shown in the figure, a cylinder 13 is installed in a crosshead 12 equipped with a die 11 consisting of a tie and a point that serves as an outlet for extruding the product. is sent to the stomach shead 12 by the screw 15 while being melted by heating,
The tensile strength body 1 introduced into the crosshead 12 is extrusion coated.

An example of production carried out using such an extrusion device will be shown.

A galvanized steel wire with a diameter of 2.6 mm is used as the tensile strength member 1, and after preheating it with hot air, the crosshead 12
and extrusion coating.

An adhesive polyolefin resin was used as the resin for the inner layer 2, and the inner layer 2 was coated to have a diameter of 4.0 mm. The manufacturing conditions at this time are shown below. The heating section of the cylinder 13 is divided into four blocks a to d, and the cylinder a % d at the extrusion temperature shown below indicates the heating temperature of each block B to d.

Line speed: 20m/min Point diameter: 3. Omm Die diameter: 4. Omm Extrusion temperature Cylinder a 160°C Cylinder b 180°C Cylinder 0 190°C Cylinder d 185°C Crosshead 165°C Die 155°C Irregularities due to melt fracture were observed on the surface of the inner layer 2 formed in this way.

In this way, the outer layer 3 made of high-density polyethylene and provided with a spiral groove 4 was extrusion coated around the steel wire 1 coated with the inner layer 3 to obtain a grooved spacer having an outer diameter of 10.0+am.

The manufacturing conditions of Party B are shown below.

Linear speed: 3m/min Extrusion temperature Niji cylinder a 160℃ cylinder b 170℃ cylinder 0 180℃ cylinder d 180℃ crosshead 180℃ die 170℃ When it was cut into lengths and left in a constant temperature bath at 60° C. for 1 hour, the amount of protrusion δ of the inner layer 2 due to slippage between the inner layer 2 and the outer layer 3 (see FIG. 3) was 0.3 mm.

Note that this amount of protrusion indicates the average of five tests.

For comparison, grooved spacers were manufactured in the same manner except that the extrusion temperature of the inner layer was changed as described below.

Extrusion temperature: Niji cylinder a: 160°C Cylinder b: 180°C Cylinder: 0:190°C Cylinder d: 200°C Riss head: 200°C Die: 200°C Note that no irregularities due to melt flankers were observed on the surface of the inner layer 2 molded at this extrusion temperature. Ta.

When the protrusion amount δ of the groove spacer obtained under the same conditions as the conventional one was measured under the above conditions, it was found to be 1.2.
mm, which was much larger than that of the above example.

<Effects of the Invention> As specifically explained above in conjunction with the examples, the grooved spacer according to the present invention has unevenness formed on the contact surface between each plastic layer, so it is suitable for use in optical fiber cables, etc. However, there is no risk of distortion or other negative effects on the optical fibers due to shrinkage or expansion of the plastic during manufacturing, installation, or after installation.

Further, by forming the uneven layer between the plastic layers by low-temperature extrusion coating, the grooved spacer of the present invention can be manufactured extremely easily and at low cost without introducing new manufacturing equipment.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a grooved spacer according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the outline of an extrusion device used in the embodiment, and Fig. 3 is an explanatory diagram showing the amount of extrusion in a test example. ,
FIG. 4 is a cross-sectional view of a grooved spacer according to the prior art. In the drawings, 1 is a central tensile strength member, 2 is an inner layer, 2a is an unevenness, 3 is an outer layer, and 4 is a spiral groove.

Claims (4)

[Claims] (1) In a grooved spacer formed by forming at least two plastic layers around a central tensile strength member and having grooves extending in the longitudinal direction on the surface of the outermost layer, irregularities are formed on the contact surfaces of the plastic layers. A grooved spacer characterized by: (2) The grooved spacer according to claim 1, wherein the innermost layer that is directly coated around the central tensile strength member is made of a plastic that has adhesive properties with the central tensile strength member. (3) In a method for manufacturing a grooved spacer, in which at least one inner layer made of plastic is extruded around a central tensile strength member, and an outermost layer having grooves extending in the longitudinal direction is further extruded and coated around the outermost layer, each of the above-mentioned A method for manufacturing a grooved spacer, characterized in that the inner layer is extruded at a low temperature that causes unevenness on the outer peripheral surface. (4) The method for manufacturing a grooved spacer according to claim 3, wherein the innermost layer directly surrounding the central tensile strength member is extruded and coated with a plastic that has adhesive properties with the central tensile strength member.