JP2001353780A - Method for producing room temperature-shrinkable tube unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce costs by eliminating a troublesome molding mold and work for engaging a room temperature-shrinkable tube 5a externally with a holding sleeve 10. SOLUTION: In the production, the tube 5a is wound onto the sleeve 10 while a rubber tape is stretched elastically. In this way, the mold and the work can be eliminated to reduce the costs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a normal-temperature connecting portion for connecting straight ends of cable conductors constituting a high-voltage power cable such as a cross-linked polyethylene insulated power cable (CV cable). The present invention relates to a method for manufacturing a cold-shrinkable tube unit for efficiently producing a shrinkable tube unit.

[0002]

2. Description of the Related Art A pair of power cables is formed by a cold-shrinkable tube (pre-molded sleeve) made of rubber, which is an elastic material, as a structure for relatively easily connecting the ends of a high-voltage power cable. 2. Description of the Related Art A structure for covering a connection portion between constituent cable conductors is known. FIG. 5 shows an example of a straight-line connection portion of a power cable using such a cold-shrinkable tube.

[0003] A pair of power cables 1 to be connected to each other,
1 comprises a cable conductor 2 covered with a cable insulator 3. Portions of the pair of power cables 1 and 1 protruding from the cable insulator 3 at ends of the cable conductors 2 are connected by a connection sleeve 4 which is a kind of conductor connector. The periphery of the connection sleeve 4 is covered with a cold shrinkable tube 5 which is a cold shrinkable insulator. The cold-shrinkable tube 5 is made of a polymer material such as rubber and is formed in a cylindrical shape, and a high pressure is applied to an inner circumferential surface portion of the insulating cylindrical portion 6 made of rubber having an insulating property at an intermediate position in the axial direction. Electrodes
A semiconductive rubber internal electrode 7 is embedded.
The outer peripheral surface of the insulating cylindrical portion 6 is covered with a semi-conductive rubber external electrode 8 which is a low voltage electrode.

FIG. 6 shows a free state of the cold-shrinkable tube 5 constituting the straight-line connection portion of the power cable as described above. The cold-shrinkable tubes 5 shown in FIG. 5 and FIGS. 9 to 10 described later and the cold-shrinkable tubes 5 shown in other drawings including FIG. 6 have different shapes, but are basically the same. belongs to. The inner diameter R ₅ of the cold-shrinkable tube 5 in the free state shown in FIG. 6 is smaller than the outer diameter D ₃ (FIG. 5) of the cable insulator 3 (R ₅ <D ₃ ). In order to manufacture such a cold-shrinkable tube 5, as shown in FIG. 7, a cylindrical mandrel (core) 9 having an outer peripheral surface as a cylindrical surface is inserted into a mold (not shown). The rubber material is filled into the cavity existing between the outer peripheral surface of the mandrel 9 and the inner peripheral surface of the mold. In this case, since the rubber material forming the insulating tubular portion 6 and the rubber material forming the internal electrode 7 and the external electrode 8 are different from each other, the forming operation of the cold shrinkable tube 5 is shown in FIG. In three steps.

That is, as a first step, a semiconductive rubber material is injected into a first cavity provided by a first mold (not shown) at a portion facing the outer peripheral surface of the intermediate portion of the mandrel 9. After heating the rubber material,
As shown in (A), the internal electrode 7 is formed. Next, after the internal electrode 7 is cooled, the first mold is removed, and the process proceeds to the second step. In the second step, a second mold (not shown) provided the outer surface of the internal electrode 7 and the portion facing the outer surface of the mandrel 9 exposed from both ends in the axial direction of the internal electrode 7. After the insulating rubber material is injected into the cavity, the rubber material is heated to form the insulating cylindrical portion 6 as shown in FIG. 8B. Next, after the insulating cylinder 6 is cooled, the second mold is removed, and the process proceeds to the third step. In the third step, a third mold (not shown) is provided on a portion of the outer peripheral surface of the insulating cylindrical portion 6 and a portion of the mandrel 9 exposed from the insulating cylindrical portion 6 and facing the outer peripheral surface. Then, a semiconductive rubber material is injected, and then the rubber material is heated to form the external electrode 8. Then, in the final fourth step, after cooling the external electrode 8, the mandrel 9 is pulled out from the inside of the internal electrode 7, the insulating cylinder 6, and the external electrode 8, as shown in FIG. The cold-shrinkable tube 5 is completed as described above.

As shown in FIG. 9, the cold-shrinkable tubes 5 manufactured as described above should be connected to each other while being elastically expanded in diameter and externally fitted to a cylindrical holding sleeve 10. Prior to connecting the ends of the cable conductors 2 of the pair of power cables 1 and 1 with the connection sleeve 4 (see FIG. 5 described above), the ends are fitted to the intermediate portion of one of the power cables 1. . Then, the pair of power cables 1,
After connecting the ends of the one cable conductor 2 with the connection sleeve 4, the cold shrinkable tube 5 is bridged between the cable insulators 3 constituting the pair of power cables 1. After being moved to the position, the holding sleeve 10 is pulled out from the inner diameter side of the cold shrinkable tube 5.

[0007] The holding sleeve 10 is formed by winding a wire in a spiral shape.
Is inserted into the room-temperature shrinkable tube 5 in a state where the diameter is increased. At the time of assembling the straight connecting portion, the end 11 of the wire is pulled out through the inside of the holding sleeve 10 as shown in FIG. As a result, the diameter of the cold-shrinkable tube 5 is reduced from one end in the axial direction (the left end in FIG. 9). As the holding sleeve 10 is pulled out from the inner diameter side of the cold-shrinkable tube 5 in this manner, the cold-shrinkable tube 5 is reduced in diameter by its own elasticity. Each of the power cables 1 is elastically in contact with an outer peripheral surface of an end of the cable insulator 3.

The above-mentioned cold-shrinkable tube 5 constituting the above-mentioned straight-line connection portion of the power cable forms a cold-shrinkable tube unit by combining with the holding sleeve 10 at a factory or a work site. Is externally fitted to an intermediate portion of any one of the power cables 1. Then, as described above, after the cable conductors 2 constituting the pair of power cables 1 and 1 are connected to each other by the connection sleeve 4, the cable insulators 3 and 3 constituting the cables 1 and 1 are connected to each other. Then, the holding sleeve is removed from the inside diameter side of the cold-shrinkable tube 5.

The operation of assembling the cold-shrinkable tube unit by combining the cold-shrinkable tube 5 and the holding sleeve 10 as described above is performed by combining the diameter-expanding jig 12 and the pressing jig 13 as shown in FIG. It is performed by an assembling apparatus provided.
The expanding jig 12 among them is a cold-shrinkable tube 5.
A small-diameter circular rod portion 14 which can be externally fitted with its diameter reduced.
And the other end in the axial direction (the left end in FIG. 10) of the large-diameter cylindrical portion 15 which can be externally fitted to the cold-shrinkable tube 5 in a state where the diameter thereof is expanded. It is made continuous by a guide inclined portion 16 having a shape. The holding sleeve 10 to which the cold-shrinkable tube 5 is to be fitted is made freely insertable inside the large-diameter cylindrical portion 15.

In order to externally fit the cold-shrinkable tube 5 to the holding sleeve 10, first, as shown in FIG. The pressing jig 13 is externally fitted to the portion 14 and the base jig (left end in FIG. 10) of the cold-shrinkable tube 5 is opposed to the pressing jig 13. Then, the pressing jig 13 is moved toward the large-diameter cylindrical portion 15 of the diameter-expanding jig 12 with the diameter-expanding jig 12 kept stationary. As a result, as shown in FIG. 10B, the diameter of the cold-shrinkable tube 5 is sequentially expanded from the tip (the right end in FIG. 10), and finally as shown in FIG. , The cold shrinkable tube 5
The whole is in a state of being externally fitted to the large-diameter cylindrical portion 15.

When the whole cold-shrinkable tube 5 is externally fitted to the large-diameter cylindrical portion 15 in this manner, the pressing jig 13 and the holding sleeve 10 are kept stationary while the expanding-diameter jig is kept. 12 is withdrawn from the inside of the cold shrinkable tube 5. Along with this operation, the cold-shrinkable tube 5 moves to the outer peripheral surface of the holding sleeve 10 while reducing the diameter from the distal end as shown in FIG. Then, in a state where the diameter-expanding jig 12 is completely removed from the inside of the cold-shrinkable tube 5, the cold-shrinkable tube 5 is placed on the outer peripheral surface of the holding sleeve 10 as shown in FIG. It will be in the state of being fitted outside.

[0012]

The cold-shrinkable tube 5 is manufactured as described above, and the cold-shrinkable tube 5 is further formed.
As described above, in the case of the conventional method of combining with the holding sleeve 10 to form the cold-shrinkable tube unit, it is inevitable that the manufacturing cost increases. The reason for this is that the processing cost of the cold shrinkable tube 5 is increased, and that a step of combining the cold shrinkable tube 5 with the holding sleeve 10 is required.

First, the reason why the processing cost of the cold shrinkable tube 5 is increased is as follows. In order to form the cold-shrinkable tube 5, a first mold for molding the internal electrode 7, a second mold for molding the insulating cylinder 6, and an external electrode 8 are formed. It is necessary to prepare three types of dies with the third die. Moreover, each time the first to third steps are performed, cooling and heating must be repeated. Three
Preparing various types of dies causes an increase in processing cost of each of these dies, resulting in an increase in cost. Further, repeating cooling and heating not only causes an increase in energy consumption due to a decrease in energy efficiency, but also causes an increase in cost due to a decrease in production efficiency due to a prolonged working time. Since it is necessary to separately fit the cold-shrinkable tube 5 manufactured as described above to the holding sleeve 10, the manufacturing cost of the cold-shrinkable tube unit as a whole increases significantly. The method for manufacturing a cold-shrinkable tube unit of the present invention has been made in view of such circumstances.

[0014]

SUMMARY OF THE INVENTION A method of manufacturing a cold-shrinkable tube unit according to the present invention comprises: a cold-shrinkable tube having elasticity at normal temperature; A cold-shrinkable tube unit having a holding sleeve for preventing the inner diameter of the cold-shrinkable tube from shrinking by being held in the shrinkable tube is produced. Such a method of manufacturing a cold-shrinkable tube unit is configured by winding at least a part of the cold-shrinkable tube around the holding sleeve while elastically stretching a tape-shaped material made of an elastic material. Then, a cold-shrinkable tube having elasticity in a direction of reducing its diameter is provided around the holding sleeve.

[0015]

According to the method of manufacturing a cold shrinkable tube unit of the present invention having the above-described structure, a cold shrinkable tube can be formed without using a plurality of molds for forming a cavity. Simultaneously with this molding operation, the cold-shrinkable tube can be fitted around the holding sleeve in a state where elasticity in the direction of reducing the diameter is imparted. Further, the tape-like material constituting the cold-shrinkable tube does not need to be cooled every time the process is shifted, so that the energy efficiency can be improved. Thus, according to the method for manufacturing a cold-shrinkable tube unit of the present invention, it is possible to reduce the cost of the cold-shrinkable tube unit for forming the linear connection portion of the power cable.

[0016]

1 to 5 show an example of an embodiment of the present invention. In order to manufacture a cold-shrinkable tube unit by the manufacturing method of the present invention, first, as shown in FIG. 1, a tubular (or rod-shaped) mandrel 17 is inserted into the holding sleeve 10 without any gap. This mandrel 1
7 reinforces the holding sleeve 10, and even when an uneven force is applied to the holding sleeve 10 with the winding of the tape-like material for forming the cold-shrinkable tube described below,
The holding sleeve 10 is prevented from being deformed such as being crushed. Accordingly, when a holding sleeve having a sufficient rigidity such as a cylindrical shape is used, the mandrel may not be inserted into the holding sleeve.

In the case of the illustrated example, a semiconductive rubber or insulating rubber tape-like material is layered around the holding sleeve 10 in which the mandrel 17 is inserted inside as described above. A cold-shrinkable tube 5a having an insulating tubular portion 6a, an internal electrode 7a, and an external electrode 8a is formed in a spiral shape. At this time, the tape-shaped material is wound around the holding sleeve 9 while being stretched, so that the room-temperature shrinkable tube 5a is completed and the elasticity in the direction of reducing the diameter is applied.
The rubber material constituting the tape-like material is E.
Materials having excellent insulating properties, such as PR and silicone rubber, can be preferably used. When a semiconductive rubber is used, a powder of a conductive material is mixed into such a rubber material.

In the example shown in FIG. 2, first, as shown in FIG. 2, the inner electrode 7a and the inner diameter side portions at both ends of the insulating cylinder 6a are separated by different types for each of the internal electrode 7a and the insulating cylinder 6a. Formed of a tape-shaped material. That is, the inner electrode 6a is formed by winding a semiconductive rubber tape material in multiple layers, and both ends of the insulating cylindrical portion 6a are formed by winding an insulating rubber tape material in multiple layers. The inner diameter side portion is formed. Next, as shown in FIG. 3, the remaining portion of the insulating cylindrical portion 6a is formed by winding the insulating rubber tape-shaped material in multiple layers, and the insulating cylindrical portion 6a and the holding sleeve 10 are further formed. The external electrode 8a is formed by winding a semiconductive rubber tape-like material in multiple layers around the portion exposed from the insulating cylindrical portion 6a on the outer peripheral surface.

The insulating cylinder 6a and the internal electrode 7a
The order in which the external electrodes 8a are formed is not particularly limited as long as the operation of winding the tape-shaped material can be performed. In either case, a tape material having a two-phase structure in which a crosslinked layer made of a crosslinked rubber material and an uncrosslinked layer made of an uncrosslinked rubber material can be used. As the uncrosslinked rubber material used in this case, a room temperature crosslinking material or a material containing a water crosslinking agent can be used. After winding the tape material having such a two-phase structure, if the uncrosslinked layer is crosslinked, the wound tape material is integrated, and the ends of the tape material are bonded with an adhesive or the like. Even without this, it is possible to reliably prevent the tape-shaped material from being unraveled. Further, with the crosslinking, it is possible to fill minute gaps (△ voids) existing in the inside by the thickness of the tape-shaped material.

Further, it is not always necessary to form the internal electrode 7a by winding a tape-shaped material.
For example, an internal electrode formed in a cylindrical shape in advance can be fitted to a predetermined portion of the holding sleeve 10 while expanding its diameter.
Since the shape of the internal electrode is simple and the elasticity of the internal electrode alone is not so large, even if a cylindrical internal electrode is formed in advance, and this internal electrode is externally fitted to the holding sleeve 10, the internal electrode shrinks at room temperature. The manufacturing cost of the mold tube unit does not increase so much (the cost can be reduced compared to the conventional case).

In any case, if the insulating cylindrical portion 6a, the internal electrode 7a, and the external electrode 8a are formed as described above, the rubber tape material is heated as necessary. After vulcanization, as shown in FIG. 4, the mandrel 17 is removed from the inside of the holding sleeve 10 to complete a cold-shrinkable tube unit 18. Since a uniform force is applied to the holding sleeve 10 from the completed cold-shrinkable tube unit 18, the mandrel 1
Even when the holding sleeve 10 is removed, the holding sleeve 10 does not collapse. The room-temperature shrinkable tube unit 18 thus obtained is connected to a pair of power cables 1 and 1 to be connected as shown in FIG. Between the cable insulators 3, 3 to form a straight connection portion.

According to the method of manufacturing the cold shrinkable tube unit of the present invention having the above-described structure, the cold shrinkable tube 5a can be formed without using a plurality of molds for forming the cavity. Moreover, at the same time as the molding operation, the cold-shrinkable tube 5a can be fitted around the holding sleeve 10 in a state where elasticity in a direction of reducing the diameter is imparted. For this reason, the cost can be reduced by omitting the mold that increases the cost. In addition, the operation of winding the tape-shaped material can be easily performed by, for example, rotating the mandrel 17 and the holding sleeve 10 and winding the tape-shaped material around the holding sleeve 10 while pulling the tape-shaped material. . In addition, the winding state can be easily changed by changing the feeding position of the tape-like material by an NC controller or the like. Therefore, even if the shape and structure of the cold-shrinkable tube 5 to be manufactured are changed, it can be easily coped with by changing the program of the NC controller. Further, the tape-shaped material constituting the cold-shrinkable tube 5 does not need to be cooled every time the process is shifted, so that the energy efficiency can be improved and the processing time can be shortened. Thus, according to the method for manufacturing a cold-shrinkable tube unit of the present invention, it is possible to reduce the cost of the cold-shrinkable tube unit 18 for forming the linear connection portion of the power cable.

[0023]

The method for producing a cold-shrinkable tube unit according to the present invention is constructed and operates as described above.
Manufacture of cold-shrinkable tubing to constitute a straight connection for power cables without using expensive molds
Moreover, it can be performed efficiently. Therefore, it is possible to reduce the cost of the cold-shrinkable tube unit, that is, the cost of the straight-line connecting portion for the power cable.

[Brief description of the drawings]

FIG. 1 is a half sectional view in an axial direction and a sectional view in a direction perpendicular to an axis, showing a preparation process according to an embodiment of the present invention.

FIG. 2 is a view similar to FIG. 1, showing a subsequent step.

FIG. 3 is a view similar to FIG. 1, showing a subsequent step.

FIG. 4 is a view similar to FIG. 1, showing a completed state;

FIG. 5 shows one of the straight-line connecting portions of the power cable assembled using the cold-shrinkable tube unit to which the present invention is applied.
Sectional drawing which shows an example.

FIG. 6 is a half-cut side view showing only the cold-shrinkable tube.

FIG. 7 is a half-cut side view showing a state before a mandrel is extracted from a cold-shrinkable tube manufactured by a conventional manufacturing method.

FIG. 8 is a cross-sectional view illustrating a conventional method for manufacturing a cold-shrinkable tube in the order of steps.

FIG. 9 is a sectional view sequentially showing a state in which the holding sleeve is removed from the inside of the cold-shrinkable tube.

FIG. 10 is a sectional view showing an operation of fitting the cold-shrinkable tube to the holding sleeve in the order of steps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power cable 2 Cable conductor 3 Cable insulator 4 Connection sleeve 5, 5a Cold-shrinkable tube 6, 6a Insulation cylinder part 7, 7a Internal electrode 8, 8a External electrode 9 Mandrel 10 Holding sleeve 11 End part 12 Jig 13 Pressing jig 14 Small diameter cylindrical part 15 Large diameter cylindrical part 16 Guide inclined part 17 Mandrel 18 Room temperature shrinkable tube unit

Claims (1)

[Claims] 1. A cold-shrinkable tube having elasticity at room temperature, and held in the cold-shrinkable tube while the inner diameter of the cold-shrinkable tube is elastically expanded.
A cold-shrinkable tube unit comprising a holding sleeve for preventing the inner diameter of the cold-shrinkable tube from shrinking, wherein at least a part of the cold-shrinkable tube is a tape-shaped tube made of an elastic material. Manufacture of a cold-shrinkable tube unit which is constituted by winding the material around the holding sleeve while elastically stretching and stretching, and providing a cold-shrinkable tube having elasticity in a direction of reducing its diameter around the holding sleeve. Method.