JP2000295752A - Method of forming insulating tube and cable connection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming an insulating tube where the insertion of a cable can be performed easily, and a cable connection using this insulating tube. SOLUTION: This insulating tube covers the connecting part of the conductors of cables, and it is equipped with a linear body 4 inserted from its on end to the other end. Space is made between the inside periphery of the insulating tube and the outside periphery of the cable by the linear body 4, and a space is made between the inside periphery of the insulating tube and the outside periphery of the cable so as to lighten the frictional resistance, and the air within the insulating cylinder is discharged from this space so as to facilitate the insertion of the cable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating tube and a method for forming a cable connecting portion using the insulating tube.

[0002]

2. Description of the Related Art There are various types of connection parts for power cables, and one of them is a self-shrink type connection part using an insulating cylinder. The procedure for assembling the connecting portion using the male and female fittings will be described as follows. First, a male fitting is attached to one end of the cable that has been stripped in advance, and a female fitting is attached to the other end of the cable. Press in these cable ends from both sides of the insulation tube. At this time, it is not necessary to increase the diameter of the insulating cylinder. The male fitting and the female fitting are connected in the insulating cylinder to form a cable connection part.

[0003] In addition, there is a method of forming a connecting portion using a diameter increasing jig. An insulating tube whose diameter has been expanded by a diameter-expanding jig is fitted into one end of the cable which has been stripped in advance, and is released. Next, after the conductor at the end of the cable is compression-connected, the insulating cylinder is positioned above the compression connection. Then, the diameter increasing jig is removed, and the insulating tube is brought into close contact with the cable by the self-contracting force of the insulating tube to form a cable connection portion.

[0004]

However, such an insulating cylinder has a problem that the workability of forming a connection portion is not good due to the following circumstances.

In general, the inner diameter of the insulating cylinder is set to be smaller than the outer diameter of the cable insulator by 1 mm or less because the insulating cylinder needs to be brought into close contact with the cable by the self-shrinking force.
Therefore, in the method of inserting the cable from both sides of the insulating cylinder without expanding the diameter, the frictional resistance between the insulating cylinder and the cable is large, and the insertion cannot be performed easily. Further, since the insulating cylinder and the cable are in close contact with each other, it is not easy to discharge the air accumulated in the insulating cylinder, and the air pressure itself becomes the insertion resistance of the cable.

[0006] In the method using a diameter-expanding jig, not only is it necessary to release the insulating tube to one of the cables in advance, but also it is necessary to expand the insulating tube and remove the diameter-expanding jig. Workability is not good.

Accordingly, a main object of the present invention is to provide an insulating tube in which a cable can be easily inserted, and a method of forming a cable connecting portion using this insulating tube, which does not require the insulating tube to be escaped to one of the cables in advance. To provide.

[0008]

According to the present invention, the above object is attained by at least one of the following three means. A first feature is that a linear body is inserted from one end of the insulating cylinder to the other end. A gap is formed between the inner circumference of the insulating cylinder and the outer circumference of the cable by the linear body, a gap is formed between the inner circumference of the insulating cylinder and the outer circumference of the cable to reduce the frictional resistance, and the internal air is removed from the gap. Is discharged.

Here, it is preferable that the linear body has a coating formed on the outer periphery of a tensile strength material. As the high-strength material, a metal wire such as copper or steel, or a resin wire such as polyamide fiber or aramid fiber may be used as long as it can withstand the tension when the linear body is pulled out from between the insulating tube and the cable. Desirably, the coating is more flexible than the cable insulation material. The linear body is removed by being pulled out after the cable is inserted, but this does not damage the surface of the cable insulator. As the cable insulator, polyethylene, high-density cross-linked polyethylene or the like is usually used, and it is preferable to use a softer vinyl or the like for the covering. In particular, it is preferable that this coating does not melt due to frictional heat when the linear body is pulled out from between the insulating tube and the cable.

A method of forming a connecting portion using such an insulating tube includes a step of inserting a linear body from one end to the other end of the insulating tube, inserting a cable into the insulating tube, and insulating the outer periphery of a cable conductor connecting portion. The method includes a step of holding the tube and a step of extracting the linear body from between the insulating tube and the cable.

A second feature is that an insulating tube into which a cable end is inserted from both ends, and a groove is provided in an inner periphery of the insulating tube to allow air in the insulating tube to escape when the cable end is inserted. It is in.

The size of the groove is such that at least a part of the air when the cable is inserted into the space formed by the groove reduces the air pressure, and the insertion resistance of the cable can be reduced. The length of the groove in the axial direction of the insulating cylinder is shorter than the range in which the inner semiconductive layer is formed on the inner peripheral surface of the insulating cylinder so that electrical contact between the inner semiconductive layer and the cable side can be ensured. . It is preferable that the corner formed by the bottom surface and the side surface of the groove is formed in a curved surface so as not to damage the inner surface of the insulating cylinder during insertion.

[0013] A method of forming a cable connecting portion using an insulating tube according to the second aspect includes a step of attaching a male fitting to one cable end, a step of attaching a female fitting to the other cable end, Connecting the male and female metal fittings by inserting both cable ends into the cylinder.

In this case, it is preferable that the distance between the end of the insulator and the male fitting or the distance between the end of the insulator and the female fitting at each cable end is 10 mm or more. Since the conductor is exposed and the diameter is small between the end of the insulator and the male or female metal fittings, air in the insulating cylinder can escape into this space and be discharged through the twisted groove of the stranded conductor. it can. Conventionally, the distance between the end of the insulator and the male (female) fitting is usually 5 m.
Although it was m or more and less than 10 mm, a space where air escapes can be secured by expanding this range. Particularly, it is preferably 15 mm or more. However, if the distance is too long, the cable connecting portion itself becomes long, so that the distance is preferably up to about 20 mm.

Further, a groove may be formed along the axial direction on a contact surface of the male metal fitting or the female metal fitting with the inner peripheral surface of the insulating cylinder.
This groove also functions to release the air in the insulating cylinder, and contributes to reducing the air pressure and lowering the insertion resistance of the cable. In particular, if the groove in the insulating cylinder and the groove of this fitting are made continuous, the air accumulated in the groove in the insulating cylinder will be connected to the end of the insulator and the male (female) through the groove of the male (female) fitting. ) The air can be discharged through the twisted groove of the stranded wire conductor by guiding to the space between the fittings.

A third feature is that the insulating cylinder covers the conductor connecting portion of the cable, and the difference between the inner diameter of the insulating cylinder and the outer diameter of the cable insulator is not less than -2 mm and less than +1 mm. That is, by setting the inner diameter of the insulating cylinder to a range of at least 2 mm larger than the outer diameter of the cable insulator to less than 1 mm smaller than the outer diameter of the cable insulator, the pluggability of the cable is improved. Conventionally, the inner diameter of the insulating cylinder is about 1 mm smaller than the outer diameter of the cable insulator, so that the insertion resistance of the cable is large. However, by keeping this within the above range, the cable can be easily inserted. Preferably -1 m
m to +0.5 mm, more preferably -0.5 m
m to +0.5 mm. In particular, if the inner diameter of the insulating cylinder is set to be equal to or larger than the outer diameter of the cable insulator, the cable can be very easily inserted into the insulating cylinder. At this time, the air in the insulating cylinder is also easily discharged from the gap between the insulating cylinder and the cable. Furthermore, if the insulating tube is made of a material that contracts with time after forming the cable connection portion, it is possible to secure a necessary level of adhesion between the cable and the inner peripheral surface of the insulating tube that is set to be insufficient when the cable is inserted, A highly reliable connection can be formed in the long term. If the insulating tube having this structure is applied to a cable connection portion which has been conventionally formed using a diameter-expanding jig, the connection portion can be formed without using a diameter-expanding jig.

As described above, by increasing the inner diameter of the insulating cylinder, the pluggability of the cable is improved, but the adhesion between the inner peripheral surface of the insulating cylinder and the cable is reduced. Cover from outside with shrink tube.

That is, the method for forming a cable connecting portion according to the present invention comprises the steps of inserting a cable into an insulating tube and holding the insulating tube on the outer periphery of the cable conductor connection portion, and covering the outer periphery of the insulating tube with a shrink tube. A method for forming a cable connection portion comprising: increasing the inner diameter of the insulating tube so that the tightening force of the cable by the insulating tube is reduced to be equal to or less than the tightening force at which a predetermined electrical performance is obtained. Is compensated by the tightening force of the shrinkable tube. The degree to which the inner diameter of the insulating cylinder is increased is such that the difference from the outer diameter of the cable insulator is −2 mm or more and less than +1 mm, preferably −0.5 mm.
About +0.5 mm.

As the shrinkable tube, a tube which can obtain a tightening force enough to compensate for the reduced adhesion to the cable by increasing the inner diameter of the insulating tube may be used. Use is conceivable.
The inner diameter can be increased by the reduced tightening force of the insulating tube, and the cable can be easily inserted.

[0020]

Embodiments of the present invention will be described below. (Embodiment 1) FIG. 1 shows a cross section of an insulating cylinder in which a linear body is inserted. A connection portion is formed in this insulating cylinder by inserting a cable from both ends. This insulating cylinder is a cylindrical one having both ends formed in a tapered shape. An inner semiconductive layer 1 is formed on an inner peripheral surface, and an outer periphery is covered with an outer semiconductive layer 3. The space 3 is filled with the insulating rubber 2. Here, the inner diameter of the insulation tube is 1 m larger than the outer diameter of the cable insulator.
m smaller.

The linear member 4 is, for example, a steel wire having a wire diameter of 0.5 mm coated with vinyl. Its length should be at least enough to allow it to be inserted from one end to the other end of the insulating cylinder and to be gripped for pulling out. Outer diameter of coating is 1
mm. A pull-out fitting 5 is attached to one end of the linear body so that the end of the linear body 4 can be easily grasped. The shape and structure of the pull-out fitting 5 are not particularly limited.

At the time of forming the cable connection portion, the end of the cable is peeled off in advance, and the conductor 10, the insulator 11 (here, crosslinked polyethylene), and the outer semiconductive layer (all not shown) are exposed in order. . A male fitting 12 is attached to one cable end, and a female fitting 13 is attached to the other cable end. Here, the male fitting 12 having the outer circumferential groove is used for the female fitting 13 having the inner circumferential projection, and the male fitting 12 is inserted into the female fitting 13 so that the inner circumferential projection is engaged with the outer circumferential groove and connected. I did it. Further, the outer peripheral edge at the tip of the male fitting and the tip of the female fitting is curved so that no corner is formed, so that it can be smoothly inserted into the insulating cylinder.

The end of such a cable is inserted from both sides into an insulating cylinder in which the linear member 4 is inserted. At this time, since the linear body 4 is interposed between the inner peripheral surface of the insulating cylinder and the outer peripheral surface of the cable insulator to form a gap, the contact area on the inner and outer peripheral surfaces is reduced, and the insertion resistance is reduced. Can be. Of course, since the air inside the insulating cylinder is discharged to both ends of the insulating cylinder through the gap formed by the linear body 4,
There is no accumulation of air.

After the connection between the male fitting 12 and the female fitting 13 is completed in the insulating cylinder, the wire 4 is pulled out by grasping the pull-out fitting 5. At this time, since the vinyl of the linear member 4 is more flexible than the crosslinked polyethylene of the cable insulator, the cable insulator 11 is not damaged at the time of drawing. After the insulating tube is mounted, the outer periphery is covered with a waterproof coating layer (not shown).

(Embodiment 2) FIG. 2 is a sectional view of an insulating cylinder in which a groove for allowing air to escape is formed on the inner periphery. This insulating cylinder is also a cylindrical one having both ends formed in a tapered shape. The inner semiconductive layer 1 is formed on the inner peripheral surface, and the outer periphery is covered with the outer semiconductive layer 3. Is filled with insulating rubber 2. The same as the insulating cylinder of the first embodiment, in that the ends of the cables having the male and female fittings inserted therein are connected to each other. The broken lines in FIG. 2 indicate a male metal fitting and a female metal fitting, and the right side of the figure is a male metal fitting and the left side is a female metal fitting.

Here, a circumferential groove 20 was formed in the center of the inner semiconductive layer 1. The axial length of the groove 20 is set to such an extent that a contact surface between the outer peripheral surface of the male (female) metal fitting and the internal semiconductive layer can be secured. In addition, the depth of the groove 20 is set to such a degree that a sufficient space can be secured as an escape of the air remaining in the insulating cylinder when the cable is inserted, and the thickness of the insulating cylinder does not become too thin. Further, the corner formed between the inner peripheral surface of the insulating cylinder and the side surface of the groove 20 was formed in a curved shape so that the electric field was not concentrated. The internal semiconductive layer 1 is formed by the groove 20.
The film itself is also formed stepwise.

If such a groove 20 is formed, when the cable is inserted from both ends of the insulating cylinder, the internal air is released from the groove 2.
It can escape to zero, and it can suppress that the insertion resistance of a cable becomes large by residual air pressure.

Also, as shown in FIG.
It is also preferable to form grooves 25 along the axial direction on the outer peripheral surfaces of the second and the third. One end of the axial groove 25 communicates with the inner peripheral groove 20 of the insulating cylinder, and the other end has the male (female) metal fitting 12, 1, 2.
3 and the space formed between the end of the cable insulator 11. Therefore, the air once released to the groove 20 in the insulating cylinder is introduced into the space through the groove 25 of the male (female) fitting, and is discharged therefrom to the cable side through the twisted wire conductor groove. be able to. Male (female) fittings 12, 1
The number of grooves 25 provided in 3 is not particularly limited.

Further, it is preferable that the distance L between the male (female) metal fittings 12 and 13 and the end of the cable insulator 11 is 15 to 20 mm. The space L is a portion where the conductor 10 is exposed, and it is usually 5 to 10 mm in the past, but by increasing the space, a space where the air escapes can be secured.

(Embodiment 3) Next, a description will be given of a cable connecting portion using an insulating cylinder having a large inner diameter. This insulating tube has the same configuration as the insulating tube shown in FIG. 2, but the main difference is that the inner diameter is larger than the outer diameter of the cable insulator. The diameter difference between the inner diameter of the insulating cylinder and the outer diameter of the cable insulator was 0.2 mm. The groove 20 in the insulating cylinder in FIG. 2 may not be formed. If the inner diameter of the insulating cylinder is larger than the outer diameter of the cable insulator, the cable end can be inserted very easily. At this time, air in the insulating cylinder can also be discharged from between the inner circumference of the insulating cylinder and the outer circumference of the cable.

However, since a tightening force for bringing the insulating tube into close contact with the cable can hardly be expected, the decrease in the tightening force is compensated for by covering the shrinkable tube. That is, a contraction tube is arranged on the outer periphery of the insulating tube and contracted to give the insulating tube a predetermined tightening force on the cable.

With such an insulating tube, the air in the insulating tube can be easily discharged when the cable is inserted from between the inner periphery of the insulating tube and the outer periphery of the cable, so that the cable insertion property can be improved. Further, the shrinkable tube functions as a waterproof protective layer of the cable connection portion as it is.

Further, it is preferable that such an insulating cylinder is made of a material that contracts with time. When assembling the cable connection part, the inner diameter of the insulating cylinder is larger than the outer diameter of the cable insulator.However, the insulating cylinder shrinks with time after assembling to secure the adhesion between the insulating cylinder and the cable insulator. Thus, a highly reliable connection can be obtained for a longer period. As such a temporally shrinkable material, there is a material in which a softening material is contained in rubber, and the softening material shrinks over time by migrating to a shrinkable tube on the outer circumference of the insulating cylinder or a cable insulator on the inner circumference. In this example, an EP rubber containing a softening material was used as a temporal contraction material. In the case where the insulating cylinder is made of a temporally shrinkable material, the outer periphery of the insulating cylinder is covered with a shrink tube.

[0034]

As described above, according to the insulating tube of the present invention, the cable can be easily inserted, and the workability of forming the cable connecting portion can be improved.

[Brief description of the drawings]

FIG. 1 is an exploded view of a cable connecting portion showing an insulating tube of the present invention and a cable end portion through a linear body.

FIG. 2 is a cross-sectional view of the insulating cylinder of the present invention in which a groove for allowing air to escape is formed on the inner periphery.

FIG. 3 is a side view showing an end of a cable inserted into the insulating tube of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal semiconductive layer 2 Insulating rubber 3 External semiconductive layer 4 Linear body 5 Pull-out fitting 10 Conductor 11 Insulator 12 Male fitting 13 Female fitting 20 Groove 25 Groove

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shigeru Toyoda F-term in Asahi Metal Seiko Co., Ltd. 20-20 Toda, Kitagawara, Itami-shi, Hyogo 5G375 AA02 BA26 BB43 BB90 CA02 CA19 CB07 CB21 CB38 DB32 EA17

Claims (13)

[Claims] 1. An insulating tube for covering a conductor connection portion of a cable, wherein the insulating tube includes a linear body inserted from one end to the other end. 2. The insulating cylinder according to claim 1, wherein the linear body has a coating formed on an outer periphery of a tensile strength material, and the coating is more flexible than a cable insulator material. 3. The insulating tube according to claim 2, wherein the coating is made of a material that is not melted by frictional heat when the linear body is pulled out from between the insulating tube and the cable. 4. A step of inserting a linear body from one end to the other end of the insulating cylinder, a step of inserting a cable into the insulating cylinder, and holding the insulating cylinder on an outer periphery of a cable conductor connecting portion. Drawing out a linear body from between the two. 5. An insulating tube into which cable ends are inserted from both ends, wherein an inner periphery of the insulating tube is provided with a groove for allowing air in the insulating tube to escape when the cable end is inserted. Characterized insulating tube. 6. The insulating cylinder according to claim 5, wherein a corner formed by a bottom surface and a side surface of the groove is formed in a curved shape. 7. A step of attaching a male fitting to one end of the cable, a step of attaching a female fitting to the other end of the cable, and inserting the two ends of the cable into an insulating tube to form a male fitting and a female fitting. Connecting the cable ends, wherein the insulating tube has a groove for allowing air in the insulating tube to escape when the cable end is inserted. Formation method. 8. The cable connection according to claim 7, wherein the distance between the end of the insulator and the male fitting at the end of each cable or the distance between the end of the insulator and the female fitting is 10 mm or more. The method of forming the part. 9. The method according to claim 7, wherein a groove is formed along the axial direction on a contact surface of the male metal fitting or the female metal fitting with the inner peripheral surface of the insulating cylinder. 10. An insulating cylinder for covering a conductor connecting portion of a cable, wherein a difference between an inner diameter of the insulating cylinder and an outer diameter of the cable insulator is -2.
Insulating cylinder characterized by being not less than 1 mm and not more than +1 mm. 11. The insulating tube according to claim 10, wherein the insulating tube is made of a material that contracts with time after forming the cable connection portion. 12. A method for forming a cable connection portion, comprising: inserting a cable into an insulating tube, holding the insulating tube around the outer periphery of the cable conductor connecting portion, and covering the outer periphery of the insulating tube with a shrinkable tube. By increasing the inner diameter of the insulating tube, the tightening force of the cable by the insulating tube is reduced to the tightening force at which a predetermined electrical performance is obtained, and this reduction is compensated for by the tightening force of the shrinkable tube. A method for forming a cable connection part, characterized by comprising: 13. The method according to claim 12, wherein the inner diameter of the insulating cylinder is equal to or larger than the outer diameter of the cable insulator.