JPH052937A - Method for manufacturing foamed thin electric wire - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a method for producing a foamed small-diameter electric wire that does not have a rough appearance and can be sped up. [Structure] In a method for producing a foamed small-diameter electric wire in which a plastic containing a foaming agent is extruded around a conductor, extrusion is performed while supplying a lubricant to an inner wall surface of a die of an extruder. Diameter electric wire manufacturing method.

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 foamed thin electric wire.

[0002]

2. Description of the Related Art An example of a conventional method for manufacturing a foamed thin electric wire is shown in FIG. 1 is an extruder, in which a plastic containing a foaming agent is extruded on the outer periphery of a core wire by a crosshead 3, and the plastic containing a foaming agent is released by pressure from a die 5 and foams. is there.

By the way, in this conventional manufacturing method, the crosshead 3 is filled with plastic, and the plastic passage is very narrow at the outlet of the die 5, so that the plastic is greatly sheared. It was a structure. Therefore, the conventional technique has the following problems.

The smaller the diameter and the higher the foaming rate, the more easily the coating breaks.

When the discharge amount is increased to increase the speed,
Rough appearance of meltfracture chairs occurs.

It is considered that these problems occur because the plastic is largely sheared near the exit of the die.

Further, it has been known that this shear is greater outside the core.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, can obtain a core without a rough appearance, and can reduce coating breakage at high speed, thus enabling high speed. The present invention provides a novel method for manufacturing a foamed thin electric wire.

[0009]

That is, the gist of the present invention is to supply a lubricant to the inner wall surface of a die of an extruder in a method for producing a foamed thin electric wire in which a plastic containing a foaming agent is extruded around a conductor to foam. The method for producing a foamed small-diameter electric wire is characterized by performing extrusion molding while carrying out.

In the above, oil or gas is used as the lubricant.

The oil is required not to cause a chemical reaction with the plastics and dies used for foaming extrusion, to be difficult to penetrate into the plastics and dies, and to be not thermally decomposed during extrusion. Oil, inorganic siluree oil, and the like.

As with the oil, the gas is required not to react with the plastic or die material, to be thermally decomposed during extrusion, and to be harmless to the human body. For example, nitrogen, air, carbon dioxide gas, etc. may be mentioned.

[0013]

FIG. 1 shows an embodiment of the manufacturing method of the present invention.

Although the same parts as those in the conventional example of FIG. 2 are represented by the same reference numerals and the description thereof is omitted, the present invention is different from the conventional example in that plastic is provided between the die inner wall and the plastic near the exit of the die 5. It is to inject the air 4 of the same temperature.

As a result, the plastic and the die 5
The inner wall will not be touched directly. In addition, since the air 4 between them can move freely, it is possible to completely eliminate the shearing from the inner wall of the plastic die.

As another embodiment, oil is used in place of the air of the embodiment described above. In this case, it was confirmed that high-pressure production was possible as compared with the above-mentioned example.

As a result, the linear velocity can be further increased.

[0018]

According to the manufacturing method of the present invention described above, the following effects can be obtained, and their industrial value is great.

Prevention of appearance roughness.

Prevents the core from being cut off.

Realization of high-speed extrusion.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a crosshead used in the method of the present invention.

FIG. 2 is an explanatory diagram showing an example of a crosshead used in a conventional manufacturing method.

[Explanation of symbols]

 1 Extruder 2 Core wire 3 Crosshead 4 Air (oil) outlet 5 Die

Claims (1)

Claim: What is claimed is: 1. A method for producing a foamed small-diameter electric wire in which a plastic containing a foaming agent is extruded around a conductor to form a foamed thin electric wire, which is extruded while supplying a lubricant to an inner wall surface of a die of an extruder. A method for producing a foamed thin electric wire, which comprises molding.