JPH0315120A - Manufacture of insulated power cable - Google Patents

Abstract

PURPOSE:To obtain the title cable coated with a highly foamed and uniform insulating material without being eccentric by keeping the inner diameter of a through hole of a nipple to which a conductor is lead and the outer diameter of the conductor within a prescribed relation. CONSTITUTION:The inner diameter d1 of a through hole of a nipple 2 to which a conductor 1 is lead and the outer diameter d2 of the conductor 1 is kept in a relation of d1<=d2, and an insulator 4 is formed on the outer surrounding of the conductor passed through the hole of the nipple 2 by extrusion. Since the inner diameter d1 of the through hole of the nipple is the same as or smaller than the outer diameter d2 of the conductor, a gap is not formed between the inner diameter d1 and the diameter d2 and thus gas leakage is prevented and a highly foamed insulator 4 is obtained. Also, since no gap between the inner diameter d1 and the outer diameter d2, the conductor is prevented from slight bending and switching, and as a result the conductor is prevented from becoming eccentric and coated with the foamed insulator 4 uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing an insulated wire, and particularly to a method for manufacturing a foam insulated wire.

[Conventional technology]

Conventionally, as a method for manufacturing a foam insulated wire by extruding a foam insulator around the outer circumference of a conductor and covering it, the conductor is passed through a passage hole of a nibble 6 installed in a crosshead, as shown in Fig. 2, and the conductor is A method is known in which a foamed insulated wire 7 is manufactured by passing the conductor 1 through a passage hole of a die 3 and extruding a foamed insulator 4 around the conductor 1 to cover it.

At this time, the inner diameter d1 of the tip of the passage hole of the nipple described above
is set to satisfy the relationship dl > d2 with respect to the conductor outer diameter d2. In particular, with reference to the non-aligning crosshead, the ratio of the inner diameter dl of the tip of the nipple passage hole to the outer diameter d2 of the conductor is small, with a relationship of 1.006≦dl/d2≦1.05. A gap is formed between the inner diameter d1 and the outer diameter d2.

[Problems to be Solved by the Invention] However, in the conventional foam insulated wire manufacturing method described above,
While being kneaded in a cylinder, it is raised to a predetermined temperature,
A softened thermoplastic resin containing a blowing agent that decomposes to generate gas and is guided into the crosshead is extruded and coated on the outer periphery of the conductor that passes through the passage hole of the nipple and the passage hole of the die, and immediately after passing through the die. Since the gas is diffused to form a foamed insulator, since the inner diameter d1 of the tip of the passage hole of the nipple is larger than the outer diameter d2 of the conductor, the gas flows from the gap between the inner diameter dl and the outer diameter d2 of the conductor. Since it leaked to the incoming wire side, a highly foamed insulator could not be obtained, and this method was difficult to produce a highly foamed insulated wire.

Also, the inner diameter dl of the tip of the nipple passage hole and the outer diameter d of the conductor.
Due to the gap formed between z, small bends in the conductor and deflection of the conductor cannot be corrected, resulting in eccentricity and a problem in that a uniformly foamed insulator cannot be obtained.

The present invention aims to improve the above-mentioned drawbacks of the prior art and to provide a method for manufacturing an insulated wire made of a uniform, highly foamed ground edge without eccentricity.

[Means for Solving the Problems] The present invention is directed to manufacturing an insulated wire in which a conductor is passed through each passage hole of a nipple and a die provided in a crosshead, and an insulated wire is extruded and covered around the outer periphery of the conductor. In the method, an inner diameter d1 of the passage hole of the nipple and an outer diameter d2 of the conductor satisfy di≦d2.
An insulator is extruded and coated on the outer periphery of the conductor that has passed through the passage hole of the nipple so as to satisfy the following relationship.

As the insulator, thermoplastic resins such as polyethylene, foamed polyethylene, polypropylene, foamed polypropylene, and polyvinyl chloride are used.

[Function 1 In the present invention, the inner diameter d of the passage hole of the nibble through which the conductor passes!
Since the outer diameter d2 of the conductor does not satisfy the relationship d1≦d2 and the outer periphery of the conductor passing through the nipple passage hole is extruded and coated with an insulator, the inner diameter d1 of the nipple passage hole is the same as that of the conductor. Since the outer diameter is the same as or smaller than the outer diameter d2, no gap is formed between the inner diameter dl and the outer fM d Z, which prevents gas from leaking, resulting in a highly foamed foam insulator and a highly foamed non-green electric wire. I can do it myself. Also, there is a gear nog between the inner diameter d+ and the outer diameter 82.
Since the conductor is not bent, the small curve of the conductor can be corrected and the deflection of the conductor can be corrected, and by reducing the occurrence of eccentricity η, a uniformly foamed foam insulator can be obtained.

F Example] FIG. 1 shows an example of the method for manufacturing an insulated wire of the present invention.

1 is a conductor, 2 is a nipple, 3 is a die, 4 is an insulator, 5
is a foamed polyethylene insulated wire.

The conductor is made of a single mild steel wire with a wire diameter of 1.05 g, and the insulator 4 is made of foamed polyethylene.

The inner diameter of the tip installed inside the crosshead is 1. A conductor 1 having a wire diameter of 1.05 am fed out from a feeder (not shown) is passed through the nibble 2 of the passage hole made of the same material. At this time, the wire diameter is 1. "05+am conductor 1 is connected to 1.04t+i through the passage hole of nipple 2. Then, immediately after passing through, conductor 1 with strand diameter 1.04mm
A die 3 was passed through the outer periphery of the wire to extrude and cover the foamed polyethylene insulator 4, thereby producing a foamed polyethylene insulated wire 5 having an outer diameter of 5.0llI1. As a result of measuring the foaming degree and capacitance of this foamed polyethylene insulated wire 5, the foaming degree was 49.5%, and the capacitance was 55.6±0.8PP/
It is one.

Note that the working conditions such as extrusion speed, screw rotation, and extrusion temperature were the same as in the previous example. As a comparative example, the inner diameter of the tip installed in the crosshead was
, 07ss, a conductor 1 with a wire diameter of 1.04 mm is fed out from a feeder (not shown) into the nipple 6 of the passage hole.
The diameter of the cable immediately after passing through it! ．． A die 3 is passed through the outer periphery of the 04ir+ conductor 1, and an insulating layer 4 made of foamed polyethylene is extruded and covered, and the outer diameter of the insulator is 5. OIII
A foamed polyethylene insulated wire 7 was manufactured. This departure is 7!
q Polyethylene insulated wire 70 degree of foaming, capacitance determined (
As a result, the degree of foaming was 46.9%, and the capacitance was 56.7±1.
0PP, 1. The obtained foamed polyethylene insulated wire has a foaming degree of 2.6% compared to the foamed polyethylene of the comparative example.
It was possible to improve the capacitance by 1.1PF/l.

In this way, the inner diameter dl of the tip of the nipple passage hole through which the conductor passes and the outer diameter d2 of the conductor satisfy the relationship d+<dz, and the foamed insulator is applied around the outer periphery of the conductor that has passed through the nipple passage hole. By using the extrusion method for producing a foamed insulated wire, it was possible to prevent gas leakage, obtain a highly foamed polyethylene insulator, and produce a foamed polyethylene insulator with a high degree of foaming. In addition, since no gap is formed between the inner diameter of the tip of the nipple passage hole and the outer diameter of the conductor, small bends in the conductor and deflection of the conductor can be corrected.
A foamed insulator with uniform foaming while eliminating eccentricity was obtained.

[Effects of the Invention] As explained above, according to the insulated wire manufacturing method of the present invention, the inner diameter d1 of the passage hole of the nibble through which the conductor passes and the outer diameter d2 of the conductor are d! By satisfying the relationship ≦d2,
Since the structure is such that an insulator is extruded and coated on the outer periphery of the conductor that has passed through the passage hole of the nipple, the inner diameter dl of the nipple passage hole is the same as or smaller than the outer diameter d2 of the conductor, so there is a difference between the inner diameter dls and the outer diameter dz. Since there is no gap, gas leakage can be prevented, a highly foamed insulator can be obtained, and an insulated wire with a high degree of foaming can be manufactured.

Further, since there is no gap between the inner diameter dl and the outer diameter dz, small bends in the conductor and deflection of the conductor can be corrected, eccentricity can be eliminated, and a uniformly foamed insulator can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view showing one embodiment of the method for manufacturing an insulated wire according to the present invention, and FIG. 2 is an explanatory cross-sectional view showing a conventional method for manufacturing an insulated wire. 1: Conductor 2: Nipple 3: Dice 4: Insulator 5: Foamed polyethylene insulated wire

Claims (1)

[Claims] (1) In a method for manufacturing an insulated wire in which a conductor is passed through each passage hole of a nipple and a die provided in a crosshead, and an insulator is extruded and coated on the outer periphery of the conductor, the inside diameter d_1 of the passage hole of the nipple and the outside of the conductor are The diameter d_2 is d_1≦d_
2. A method for manufacturing an insulated wire, which comprises extruding and coating an insulator on the outer periphery of a conductor that has passed through a passage hole of the nipple so as to satisfy the following relationship.