JPS61292819A - Nipple for core wire covering apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a nipple used in a core wave RIV apparatus for manufacturing highly foamed flexible cables and the like.

(Prior Art) The above-mentioned highly foamed flexible cable is used as a core wire of a coaxial cable, and has a structure in which a core wire such as a mild steel wire is covered with a resin foam layer constituting an insulating material. Such a core wire is manufactured by applying resin to the surface of the core wire using a nipple of an extruder and foaming the adhered resin. The nipple is a cylindrical metal member having a core wire passage in the center and an annular resin passage around the periphery;
The molten resin adheres to the core wire near the tip of the nipple.

(Problems to be Solved by the Invention) In order to reliably adhere the resin to the core wire and solidify it, it is necessary to maintain the resin at a high temperature and to maintain the core wire at a low temperature. However, in the conventional structure, the heat of the molten resin is transmitted to the core wire through the nipple, causing the temperature of the resin to drop and the temperature of the core wire to rise, which may cause a problem in that the adhesion strength of the resin to the core wire is low.

Another problem arises in that the resin solidifies within the passageway and blocks the passageway.

These problems can be solved to some extent by making the nipples made of resin and increasing the insulation of the nipples, but if the nipples are made of resin, the molten resin will adhere to the nipples and solidify, making the nipples impossible to clean. The problem of contamination arises.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a core wire passage through which the core wire passes in the center of the cylindrical nipple, and melts the resin around the outer peripheral surface of the nipple. Provides a resin passageway through which
In the nipple of the core wire coating device in which resin is attached to the core wire in front of the tip of the nipple, the nipple is provided with an inner cylinder surrounding the core wire passage and an outer cylinder facing the resin passage,
The tip of the outer cylinder is made to protrude further forward than the tip of the inner cylinder, the inner diameter of the outer cylinder tip is made larger than the inner diameter of the inner cylinder tip, and a heat insulating section extending rearward from between the two tips is provided inside. It is characterized in that it is formed between a tube and an outer tube, and the outer tube is made of a metal material.

(Function) According to the above structure, the heat of the molten resin flowing through the resin passage is transmitted to the outer cylinder, but due to the action of the heat insulating layer between the outer cylinder and the inner cylinder, the heat is significantly prevented from being transmitted from the outer cylinder to the inner cylinder. regulated by.

Therefore, the molten resin and the core wire pass through the nipple in a high temperature state and a low temperature state, respectively, and the resin is firmly attached to the core wire at the attachment position in front of the tip of the nipple.

While the core wire passes through the inward tip, the core wire moves while maintaining a radial gap with respect to the outer tube and does not come into contact with the outer tube. Therefore, the heat of the resin is also prevented from being transmitted from the tip of the outer cylinder to the core wire.

Further, the resin flows from the tip of the outer cylinder to the attachment position in front of the outer cylinder, and the resin does not flow into the gap or the heat insulating layer behind it. Therefore, it is possible to prevent the resin from remaining in a solidified state at the tip of the nipple and from deteriorating the heat insulating performance of the heat insulating layer.

(Example ゛) In the drawing, which is a schematic cross-sectional view, a generally cylindrical nipple 1 has a core wire passage M in the center, and a solid (or vibrator-shaped) core wire A passes through the core wire passage M in the direction of arrow F ( forward).

The nipple 1 is a metal component made of iron or the like and is incorporated into the housing 2 of the extruder, and includes an inner tube 3 and an outer tube 4.

The inner tube 3 and the outer tube 4 each include a cylindrical portion 5.6 and a tapered portion 7.8 integrally projecting forward from their front ends. The outer peripheral surface of the rear half of the cylindrical portion 5 is fixed to the inner peripheral surface of the cylindrical portion 6 by means such as press fitting or screws.

The inner tube 3 forms the core wire passage M having a circular cross section inside thereof, and the inner circumferential surface 11 of the tip portion 10 is connected to the outer circumferential surface a of the core wire A.
It is a cylindrical surface that is parallel to and has an inner diameter slightly larger than the outer diameter of the core wire A.

The outer cylinder 4 forms a resin passage N having an annular cross section on the outer circumferential surface and the outer circumferential surface of the housing 2, and the inner circumferential surface 16 of the tip 15 is a cylindrical surface approximately parallel to the outer circumferential surface a of the core wire A. It has become. The inner circumferential surface 16 has a larger diameter than the inner circumferential surface 11;
A gap 17 having a relatively wide radial width <VA, for example, 0.25 aai) is formed in an annular shape between the core wire outer circumferential surface a and the core wire outer circumferential surface a. Further, the distal end portion 15 and the inner circumferential surface 16 protrude further forward than the distal end portion 10 and the inner circumferential surface 11.

Between the tapered parts 7.8 and between the front half of the cylindrical part 5.6, a series of spaces 20 (air insulation layers) are formed in an annular shape.

Although not shown, a core wire/heating device and a temperature sensor are installed on the upstream side of the extruder, and using these, the core wire △ is maintained at a predetermined low temperature (approximately 50±5°C) and the nipple is heated. 1.

The extruder is also equipped with a device for maintaining the molten resin at a high temperature (approximately 120° C.) and supplying it to the resin passage N under pressure.

According to the above configuration, the heat of the molten resin B flowing through the resin passage N is transmitted to the outer cylinder 4, but the transfer (escaping) of heat from the outer cylinder N4 to the inner cylinder 3 is largely restricted by the space 20 (insulating layer). be done. Therefore, the resin B and the core wire A pass through the nipple 1 while remaining in a high temperature state and a low temperature state, respectively.
The resin B is attached to the core wire A at an attachment position P in front of the tip of the core wire A to form a coating layer S. In this way, the high-temperature resin B adheres to the low-temperature core wire A, so the core wire A
A thin solidified layer T of resin B is formed on the surface of the core wire A, and the resin B is firmly attached (fused) to the core wire A under the solidified layer. Of course, the resin B will not solidify in the resin passage N and will not block the resin passage N.

While the core wire A passes through the outer cylinder tip 15 in the above operation, the core wire A moves while maintaining the radial gap 17 with respect to the tip 15 and does not come into contact with the tip 15.

Therefore, the heat of the resin B is also prevented from escaping from the outer cylinder tip 15 to the core wire A.

In addition, the resin B flows from the periphery of the outer cylinder tip 15 to the attachment position P roughly along the imaginary extension surface of the tapered outer peripheral surface of the tapered portion 8,
Since the resin B does not flow into the gap 17, the resin B does not remain in a solidified state at the tip of the nipple. Therefore, the coating layer S of the resin B can always be formed on the core wire A in a desired state. Furthermore, since the resin B does not flow into the gap 17 or the space 20, the heat insulation performance of the gap 17 or the space 20 is always maintained at a high level.

When the covering layer S formed as described above passes through the attachment position P, it starts foaming to become a foamed layer Q, and the foamed layer is subjected to sizing and cooled to complete the covered cable.

(Effects of the Invention) As explained above, according to the present invention, the nipple 1 is configured so as to increase the heat insulation effect between the core wire A and the outer cylinder 4, so that the adhesion strength and adhesion state of the resin B to the core wire A can be improved. can be improved. Furthermore, since the outer shell 84 is made of metal, the outer cylinder 4 will not be contaminated by adhering solidified resin.

[Brief explanation of the drawing]

The drawing is a schematic cross-sectional view of an embodiment. DESCRIPTION OF SYMBOLS 1... Cylindrical nipple, 3... Inner cylinder, 4... Outer cylinder, 10... Inner cylinder tip, 15... Outer cylinder tip, 20... Space (insulation layer), A: Core wire, B: Molten resin, M: Core wire passage, N: Resin passage

Claims (1)

[Claims] A core wire coating device in which a core wire passage through which the core wire passes is provided in the center of a cylindrical nipple, a resin passage through which molten resin flows is provided around the outer peripheral surface of the nipple, and the resin adheres to the core wire in front of the tip of the nipple. At the nipple of
The nipple is provided with an inner cylinder that surrounds the core wire passage and an outer cylinder that faces the resin passage, and the tip of the outer cylinder is made to protrude further forward than the tip of the inner cylinder, and the inner diameter of the tip of the outer cylinder is set to the tip of the inner cylinder. A nipple for a core wire coating device, characterized in that a heat insulating layer is formed between the inner tube and the outer tube, the outer tube being made of a metal material, and the outer tube is made of a metal material.