JPH0145682B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a communication cable coupling and a method for manufacturing the same, and more particularly to a communication cable coupling having a relatively small outer diameter and excellent crosstalk characteristics, and a method for producing the same.

The most common type of conventional communication cable cutter is the strand w ₁ , as shown in Figure 1.
The core wires 1, ₂ , ₃ , and ₄ , each of which has an insulating coating covering w 2 , w 3 , and w 4 , are twisted together while giving a twist, and each of the strands w ₁ , w ₂ ,
This is a cut Q in which the center positions of w ₃ and w ₄ form a square or diamond shape in cross section. In such a Kazudo Q, crosstalk due to electromagnetic coupling can be eliminated by selecting a pair of lines so that they are orthogonal to each other, and since each core wire is twisted, Therefore, it is possible to avoid accumulation of uneven thickness of the insulation coating of each strand in the longitudinal direction and eliminate crosstalk due to electrostatic coupling, and for this reason, it is widely used as a coupling for communication cables.

However, such a conventional cut Q has a disadvantage that the outer diameter _D0 of its cross section is relatively large, and its outer periphery is extremely uneven, resulting in a relatively large diameter of the communication cable as a whole. The disadvantage is that the alignment is unstable. Looking at this numerically, in Figure 1, the wires w ₁ , w ₂ ,
The diameter of ...... is d ₀ , the core wire 1 including the insulation coating,
If the outer diameter of 2,..., etc. is d, the distance between the center lines of the figure center lines 2 and 4 is √2d, so the outer diameter D ₀ of the entire cutter Q is D ₀ =√2d+d/2+d/ 2=(1+√2)d.

In order to eliminate the drawback that the conventional cutter Q has a relatively large diameter, a cutter _Q1 having a single insulation coating as shown in FIG. 2 has recently been proposed. This has a circular cross section, and four strands w ₁ are placed in each strand storage groove of the strand holder 5, which has strand accommodating grooves 51 extending in the longitudinal direction at four equal locations on the circumference on its outer periphery. , w ₂ , w ₃ and w ₄ are housed, and a bulk insulation coating 6 is applied from the outside.
The outer diameter D ₀ is the thickness t of the bulk insulation coating 6, and the arrangement position of each strand is the same as that of the conventional cutter Q shown in FIG. 1, and the outer diameter D 0 is D ₁ =√2d+d ₀ +t, and the overall diameter is quite small. However, as can be seen from the configuration of the wire holder 5, this collective insulation coating cut _Q1 shown in FIG. 2 cannot be twisted, so it is necessary to reduce the electrostatic coupling value and improve the crosstalk characteristics. There was a drawback that I couldn't do it.

The present invention has been made in order to eliminate such conventional drawbacks, and provides a communication cable coupling that is twisted, has good crosstalk characteristics, and has a small outer diameter, and a method for manufacturing the same. It is.

Before explaining the communication cable coupling of the present invention, the manufacturing method thereof will first be explained with reference to FIG.
What is indicated by 8 as a whole is four strands w ₁ ,
The wires w ₂ , w ₃ and w ₄ are sent to an extrusion coating device 9, where an insulating coating is formed around each wire, and the wires are turned into core wires 1, 2, 3 and 4. It is cooled by the cooling device 10 and sent to the next process. The next step is a step of applying twisting using an appropriate intermediate twisting device, and the four core wires 1, 2, 3, and 4, each of which has been twisted, are twisted together in a twisting die 12 and cut into a cut.
In this case, the cut Q will be exactly the same as the conventional one shown in FIG.

Next, this cutlet Q is heated by the heating device 13 as necessary.
(this may be omitted), then passed through a heating compression die 14 where it is compressed and decompressed, transformed into a cup Qp shown in FIG. 3, cooled and fixed in a cooling device 15, and then rolled. It is wound up by a take-up device 16.

Here, the inner diameter of the heating compression die 14, that is, the outer diameter D of the reduced pressure of the cutlet Qp as a result of the compression diameter reduction process by this die 14, or ``straining process'' to borrow a common expression, will be explained. The outer diameter D should of course be smaller than the outer diameter D ₀ =(1+√2)d of the initial cutter Q. Of course, it goes without saying that this squeezing process is meaningless unless D is smaller than ₀ . But on the other hand, Katsudo Qp
The outer diameter D is the minimum outer diameter indicated by 7 in Fig. 3.
It cannot become smaller than Dmin. This minimum outer diameter Dmin is the state when the insulation covering over the wires w ₁ , w ₂ , etc. is compressed radially inward from the periphery so that all internal voids are eliminated, that is, π /4D ² _nio = 4×π/4d ² is the value of Dmin. Solving the above equation yields Dmin.=2d, so the outer diameter D of the cutlet Qp achieved as a result of compression reduction by this invention must naturally fall within the range of (1+√2)d>D≧2d. .

Since the cutlet Qp of the present invention undergoes the compression diameter reduction process described above, each of the core wires 1, 2, 3, and 4 has an outer circumferential portion that is a part of the circumference of the diameter D, as clearly shown in FIG. Corresponding approximately fan-shaped core wires 1A, 2
A, 3A, and 4A, and the outer periphery of the entire cup also has a nearly circular cross section with few irregularities.

As is clear from the above, the communication cable coupling of the present invention has (i) a small capacitive coupling value and excellent crosstalk characteristics because it is twisted;
(ii) Since it undergoes a compression diameter reduction process using a heated compression die, it will of course have a smaller diameter than a conventional cutter,
Its outer periphery approaches an almost cylindrical shape with few irregularities,
It has the advantage of being convenient for processes such as twisting the ends together or covering the sheath. In addition, the method of the present invention has the advantage that each step is relatively simple and can be carried out continuously, and the heating die, which is very important in implementation, is simple in construction and can be obtained at low cost.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a conventional cutter, FIG. 2 is a cross-sectional view showing a conventional lump-insulating cutter, FIG. 3 is a cross-sectional view showing a cutter according to an embodiment of the present invention, and FIG. FIG. 1 is a simplified side view showing an example of an apparatus used to carry out the method of the present invention. w ₁ , w ₂ , w ₃ , w ₄ ... elemental wire, 1, 2, 3, 4...
... Core wire, 1A, 2A, 3A, 4A... Core wire whose diameter has been reduced by compression, Qp... Same as above, 14... Heating die.

Claims (1)

[Scope of Claims] 1. Consisting of four twisted core wires, each of which has an outer diameter d of the insulation coating of the strands, and whose outer diameter D is (1+√2)d>D≧ A communication cable cutlet whose diameter has been compressed and reduced to 2D using a heated compression die. 2 (a) a step of sending out four strands of wire and extruding an insulating coating thereon; (b) a step of twisting each of the strands with the insulating coating formed thereon and then twisting them together; (c) the step of compressing and reducing the diameter of the ends formed by the twisting step by passing them through a heated compression die having a predetermined inner diameter; and (d) the step of cooling and fixing the ends. Method.