JP2002369365A - Method for manufacturing cylindrical member made of polymer material for connecting power cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a cost by decreasing the number of molds to be used, and reducing repeating of heating and cooling. SOLUTION: A method for manufacturing a cylindrical member made of a polymer material for connecting a power cable comprises a step of external engaging a semiconductor tube 20 for constituting an internal semiconductive layer and a tubular element 21 for constituting an external semiconductor layer with a core 9a; a step of expanding the element 21 by sending an insulating material through an injection hole 24 provided at the core 9a; and steps of sending the insulating material until the element 21 is closely contacted with an inner surface of the mold 22, and then curing the insulating material to a cold shrinkable type tube.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a tubular member made of a polymer material for connecting a power cable, which relates to an improvement of a method of manufacturing a pre-molded insulator or a cold-shrinkable tube. The pre-molded insulator is, for example, a cross-linked polyethylene insulated power cable (CV cable)
And the like, or the end portions of such cable conductors are incorporated in a prefabricated connection portion for connecting to various power devices.
On the other hand, the cold-shrinkable tube is used to form a straight connection portion that connects the ends of the high-voltage power cable as described above. The present invention is intended to reduce the cost by making such a pre-molded insulator or a cold shrinkable tube efficiently without requiring expensive equipment.

[0002]

2. Description of the Related Art Various types of structures for connecting the ends of a high-voltage power cable or the ends of a high-voltage power cable and various power devices have been known. For example, a structure that uses a cold-shrinkable tube (pre-mold sleeve) as a structure that can be easily assembled with a relatively simple structure is used. Prefabricated ones are widely used. The connection part for the power cable using the cold-shrinkable tube is a cold-shrinkable tube made of rubber, which is a kind of polymer material, and is an elastic material. It covers the connection. FIG. 9 shows an example of a connection portion for 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 insulators 3 at ends of the cable conductors 2 and 2 are connected by a conductor connector 4. The periphery of the conductor connector 4 is covered with a cold shrinkable tube 5 which is a kind of a cylindrical member made of a polymer material for connecting a power cable. The cold-shrinkable tube 5 is made of rubber, which is a kind of a polymer material, and is formed in a cylindrical shape. An internal semiconductive layer 7 made of rubber and having semiconductivity, which is an electrode, is embedded. The outer peripheral surface of the insulating cylinder 6 is covered with an external semiconductive layer 8 made of a semiconductive rubber, which is an external electrode.

FIG. 10 shows a free state of the cold-shrinkable tube 5 constituting the straight-line connection portion of the power cable as described above. Inside diameter R ₅ of cold shrink type tube 5 in a free state shown in FIG. 10, the outer diameter D ₃ of the cable insulation 3
(FIG. 9) (R ₅ <D ₃ ). Such a cold-shrinkable tube 5 is elastically expanded in diameter and externally fitted to a not-shown circular diameter expanding jig. Prior to being connected to each other by the connection sleeve 4, the power cable 1 is externally fitted to an intermediate portion of one of the power cables 1. After the ends of the cable conductors 2 of the pair of power cables 1 and 1 are connected to each other by a connection sleeve 4, the cold-shrinkable tube 5 is separated from the pair of power cables 1 and 1 by a cable insulation. After being moved to the position where it is bridged between the bodies 3, the jig for diameter expansion is withdrawn from the inner diameter side of the cold-shrinkable tube 5. With the removal of the diameter expanding jig 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, and the inner peripheral surfaces of both ends of the cold shrinkable tube 5 are removed. Each of the power cables 1 is elastically brought into contact with an outer peripheral surface of an end portion of the cable insulator 3.

[0005] In order to manufacture the above-mentioned cold-shrinkable tube 5 constituting the above-mentioned straight-line connection portion of the power cable, FIG.
As shown in the figure, in a state where a cylindrical core 9 having an outer peripheral surface as a cylindrical surface is inserted into a molding die (not shown), the outer peripheral surface of the core 9 and the inner peripheral surface of the molding die are interposed. The rubber material is filled into the cavity existing in the cavity. In this case, the rubber material forming the insulating cylindrical portion 6 and the rubber material forming the inner semiconductive layer 7 and the outer semiconductive layer 8 are different from each other.
The forming operation of the cold shrinkable tube 5 is performed in three stages as shown in FIG.

That is, first, as a first step, a semiconductive rubber material is injected into a first cavity provided by a first mold (not shown) in a portion facing the outer peripheral surface of the intermediate portion of the core 9. After that, the rubber material is heated, and FIG.
As shown in FIG. 7, the internal semiconductive layer 7 is formed. Then
After the internal semiconductive layer 7 is cooled, the first mold is removed, and then the process proceeds to the second step. In the second step, a second mold (not shown) is provided on an outer peripheral surface of the inner semiconductive layer 7 and a portion facing the outer peripheral surface of the core 9 exposed from both axial ends of the inner semiconductive layer 7. Further, an insulating rubber material is injected into the second cavity, and then the rubber material is heated to form the insulating cylinder 6 as shown in FIG. Next, after the insulating cylinder 6 is cooled, the second mold is removed, and the process proceeds to the third step. In this third step, the outer peripheral surface of the insulating cylinder 6 and the insulating cylinder 6
A semiconductive rubber material is injected into a third cavity provided by a third mold (not shown) in a portion facing the outer peripheral surface of the core 9 exposed from the above, and then the rubber material is heated. Then, the outer semiconductive layer 8 is formed. Then, in the final fourth step, after cooling the outer semiconductive layer 8, the core 9 is removed from the inside of the inner semiconductive layer 7, the insulating cylinder 6, and the outer semiconductive layer 8. By extracting the tube, a cold-shrinkable tube 5 as shown in FIG. 10 is completed.

FIG. 13 shows an example of the connection portion for the prefabricated power cable. At the ends of the cable conductors 2 and 2 constituting the pair of power cables 1 and 1, the portions exposed from the cable insulators 3 and 3 are inserted into the connection sleeve 4a from both ends of the connection sleeve 4a. are doing. The whole of the connection sleeve 4a is made of a relatively soft metal having a small electric resistance, such as a copper alloy, and has a substantially cylindrical shape. Such a connection sleeve 4a
Is caulked toward the outer peripheral surface of the end of each of the cable conductors 2 and 2 in a state where the end of each of the cable conductors 2 and 2 is inserted from the opening at both ends. Then, the ends of the cable conductors 2 are connected to each other via the connection sleeve 4a.

A substantially annular conductor fixing tool 10 supported and fixed on the outer peripheral surface of the intermediate portion of the connection sleeve 4a is embedded and supported on the inner peripheral surface of the cylindrical reinforcing insulator 11, and is made of an aluminum alloy or the like. It is supported and fixed to the inner peripheral surface of a high-voltage shield electrode 12 made of metal in a cylindrical shape. The reinforcing insulator 11 is held and fixed in a cylindrical case 13 that houses a cable connection portion (prefabricated connection portion). Therefore, the connection sleeve 4a is fixed in the case 13 via the conductor fixture 10 and the reinforcing insulator 11, and is prevented from moving in the axial direction. In this state, the wedge-shaped gap between the outer peripheral surface of the end of the cable insulator 3 and the inner peripheral surface of the end of the reinforcing insulator 11 constituting each of the power cables 1 and 1 is Pre-molded insulators 14, which are a kind of a cylindrical member made of a polymer material for connecting a power cable, are inserted. And the springs 15, 15
Accordingly, these pre-mold insulators 14 and 14 are elastically pushed into the deep portion of the gap.

The inner peripheral surfaces at both ends of the reinforcing insulator 11 are tapered surfaces 16 on the inner diameter side which are inclined in such a direction that the diameter increases toward the end opening. The outer peripheral surfaces of the leading end portions of the pre-mold insulators 14 and 14 are formed as outer diameter side tapered surfaces 17 and 17 inclined at the same angle in the same direction as the inner diameter side tapered surfaces 16 and 16. The inner peripheral surface of each of the pre-mold insulators 14 is a cylindrical surface which can be in close contact with the outer peripheral surface of the cable insulators 3 constituting the power cables 1. Therefore, in a state where the pre-mold insulators 14 and 14 are pushed into the reinforcing insulator 11, these pre-mold insulators 1
The outer peripheral surfaces of the pre-molded insulators 14 and 14 are in close contact with the outer peripheral surfaces of the cable insulators 3 and 3, respectively.

In order to secure the insulating properties of the prefabricated connecting portions as described above, the inner and outer peripheral surfaces of each of the pre-molded insulators 14 are connected to the outer peripheral surfaces of the cable insulators 3 and 3, respectively. It is necessary to securely contact the inner peripheral surface of the reinforcing insulator 11. Therefore, each of the above pre-molded insulators 1
Wedge-shaped gaps 4 and 14 between the outer peripheral surfaces of the cable insulators 3 and the inner peripheral surface of the reinforcing insulator 11 via the pressing sleeves 28 and 28 by the springs 15 and 15 respectively. I try to push strongly. With the pushing, the pre-mold insulators 14, 14 form the inner diameter side tapered surfaces 16, 16 and the outer diameter side tapered surfaces 17,
Based on the engagement with the base member 17, the core member is pushed into the gap while applying a radially inward force, so that the peripheral surfaces come into close contact with each other.

A prefabricated connecting portion as described above is constituted,
As shown in detail in FIG. 14, each of the pre-mold insulators 14 has an outer peripheral surface of an insulating layer 18 made of an insulating rubber, which is a kind of a polymer material, and has a surface opposite to the outer diameter side taper surface 17 ( The right half of FIG. 14 is covered with a semiconductive layer 19 made of semiconductive rubber, which is also a kind of polymer material. Conventionally, such a pre-mold insulator 14 composed of two layers, an insulating layer 18 and a semiconductive layer 19, is conventionally formed by sequentially disposing first and second molds around a core. Then, the insulating layer 18 and the semiconductive layer 19 are sequentially formed.

[0012]

In the case of the conventional method of manufacturing the cold-shrinkable tube 5 as described above or the pre-molded insulator 14 as described above, the manufacturing cost increases. For example, the case of manufacturing the cold shrinkable tube 5 as shown in FIGS.
Three types of molds: a first mold for molding the inner semiconductive layer 7, a second mold for molding the insulating cylinder 6, and a third mold for molding the outer semiconductive layer 8. It is necessary to prepare. Moreover, each time the first to third steps are performed, cooling and heating must be repeated. Preparing three types of dies causes an increase in the 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. Even when a pre-mold insulator 14 as shown in FIG. 14 is manufactured, the number of molds, cooling,
Even if the number of repetitions of heating is reduced by one, there is essentially the same problem. The method for manufacturing a cylindrical member made of a polymer material for connecting a power cable according to the present invention was invented in view of such circumstances.

[0013]

According to the present invention, there is provided a method for manufacturing a cylindrical member made of a polymer material for connecting a power cable, wherein the cylindrical member is entirely formed of a polymer material, and the outer layer is entirely formed on the outer peripheral surface of the inner layer. This is a method for producing a cylindrical member made of a polymer material for power cable connection, which is laminated around the circumference. In the method for manufacturing a cylindrical member made of a polymer material for connecting a power cable according to the present invention, first, a tubular element formed of a cylindrical polymer material having elasticity is fitted around a core, and The periphery of the element is covered with a mold. Then, from this state,
Another polymer material is injected between the inner peripheral surface of the tubular element and the outer peripheral surface of the core to expand the tubular element. Thereafter, the other polymer material is solidified, and the outer layer is formed by at least a part of the tubular element in the axial direction, and the inner layer is formed by the another polymer material.

[0014]

According to the method for manufacturing a cylindrical member made of a polymer material for connecting a power cable of the present invention having the above-described structure, the inner layer and the outer layer can be formed without using a plurality of molds for forming the cavity. And forming a cylindrical member made of a polymer material for connecting a power cable having a multi-layer structure having the following. In this way, there is no need to use a plurality of molds, in other words, there is no need to replace the molds during the manufacturing operation. Therefore, it is not necessary to perform cooling every time the process is shifted, thereby improving energy efficiency.
Thus, according to the method for producing a cylindrical member made of a polymer material for connecting a power cable of the present invention, a cold-shrinkable tube,
It is possible to reduce the cost of a cold-shrinkable tube for connecting a power cable such as a pre-molded insulator.

[0015]

1 to 3 show a first example of an embodiment of the present invention corresponding to claims 1 and 2. FIG. This example shows a case where a cold-shrinkable tube 5a having a straight connection portion as shown in FIG. 9 is manufactured by the manufacturing method of the present invention. In the completed state of the cold-shrinkable tube 5a, as shown in FIG. 3, the periphery of an inner semiconductive layer 7a made of semiconductive rubber existing at the center of the inner peripheral surface is covered with an insulating cylindrical portion 6a made of insulating rubber. The entire outer peripheral surface of the insulating cylindrical portion 6a is covered with an external semiconductive layer 8a made of semiconductive rubber. As the semiconductive rubber, for example, silicone rubber or ethylene propylene rubber mixed with a powder of a conductive material such as carbon powder is preferable, and as the insulating rubber, silicon rubber or ethylene propylene rubber alone is preferable. Available.

In order to manufacture the cold-shrinkable tube 5a having such a structure, first, a tube is formed in a middle portion of the core 9a with a semiconductive rubber which is a kind of a semiconductive polymer material. A semiconductive tube 20 for forming the internal semiconductive layer 7a is fitted outside. The semiconductive tube 20 can be manufactured easily and at low cost by cutting a long material formed into a hose shape by extruding semiconductive rubber into an arbitrary length.

The core 9a and the semiconductive tube 2
0 is covered with a tubular element 21 which is also formed in a cylindrical shape with semiconductive rubber which is also a kind of semiconductive polymer material. Similarly to the semiconductive tube 20, the tubular element 21 is made by cutting a long material formed into a hose shape by extruding a semiconductive rubber into an arbitrary length. It is longer than the semiconductive tube 20. Such a tubular element 21 is externally fitted to the semiconductive tube 20 and the core 9a in a state where the semiconductive tube 20 is positioned at the center in the longitudinal direction. Therefore, the inner peripheral surfaces of both ends of the tubular element 21 are in direct contact with the outer peripheral surface of the core 9a.

When the semiconductive tube 20 and the tubular element 21 are externally fitted to the core 9a in this manner, the periphery of the tubular element 21 is covered with the mold 22. The mold 22 has a two-part structure in which a pair of elements each formed in a semi-cylindrical shape are abutted with each other.
A cavity 23 for forming the cold-shrinkable tube 5a is formed between the cavity 23 and the outer peripheral surface of FIG. That is, the shape of the inner peripheral surface of the mold 22 substantially matches the shape of the outer peripheral surface of the cold-shrinkable tube 5a (when neglecting elastic deformation and heat shrinkage during processing of the cold-shrinkable tube 5a). Let me.

As described above, if the semiconductive tube 20 and the tubular element 21 are externally fitted to the core 9a and the tubular element 21 is covered with the mold 22, the tubular element 21 An insulating rubber material, which is another polymer material, is injected between the inner peripheral surface of the core and the outer peripheral surface of the core 9a. Therefore, in the case of this example, an injection hole 24 for injecting the insulating rubber material is formed in the core 9a. The upstream end of the injection hole 24 communicates with a feeding device (not shown), and the downstream end opens at a portion adjacent to the edge of the semiconductive tube 20 on the outer peripheral surface of the intermediate portion of the core 9a.

When an insulating rubber material is injected between the inner peripheral surface of the tubular element 21 and the outer peripheral surface of the core 9a through the injection hole 24, as shown in FIG. Swell. At this time, the air existing in the cavity 23 is exhausted through an exhaust hole (not shown) provided in a part of the mold 22. In this manner, the injection of the insulating rubber material while expanding the tubular element 21 is continued until the outer peripheral surface of the tubular element 21 is in close contact with the inner peripheral surface of the mold 22 as shown in FIG. I do. Further, by this injection, the pressure in the cavity 23 is increased to a desired pressure. As described above, when the outer peripheral surface of the tubular element 21 is in close contact with the inner peripheral surface of the mold 22 and the injection of the insulating rubber material is performed until the pressure in the cavity 23 reaches a desired value. The injection of the insulating rubber material is stopped, and the insulating rubber material is cured by heating (vulcanization) or the like. As a result, the insulating rubber material constitutes the insulating tubular portion 6a, the tubular element 21 constitutes the outer semiconductive layer 8a, and the semiconductive tube 20 constitutes the inner semiconductive layer 7a. Adjacent rubber materials are integrally bonded to each other with heating and pressurization for curing the insulating rubber material.

After the insulating rubber material is sufficiently cured to form the insulating cylinder 6a, the core 9a is separated from the insulating cylinder 6a, the outer semiconductive layer 8a, and the inner cylinder. It is pulled out from the inside of the semiconductive layer 7a. Along with this drawing operation, the insulating cylindrical portion 6a and the insulating rubber cured in the injection hole 24 are cut off at the downstream end opening of the injection hole 24. Therefore, fine irregularities are formed on a portion of the inner peripheral surface of the insulating cylindrical portion 6a adjacent to the edge of the inner semiconductive layer 7a. However, since this portion is not a portion requiring particularly strict characteristics in terms of maintaining the electrical characteristics of the linear connection portion, there is no particular problem. On the contrary,
Open the downstream end opening of the injection hole 24 with the cold-shrinkable sleeve 5
a, that is, near both ends of the outer semiconductive layer 8a and exposed to the inner peripheral surface of the cold-shrinkable tube 5a, there is a problem in terms of maintaining the electrical characteristics. Tends to occur. The downstream end opening of the injection hole 24 is provided at a portion facing the inner peripheral surface of the semiconductive tube 20 constituting the internal semiconductive layer 7a, and a part of the semiconductive tube 20 in the circumferential direction is provided. While elastically expanding the diameter of
The above-described operation of injecting the insulating rubber can also be performed. Even in this case, there is no particular problem in terms of maintaining the electrical characteristics.

Next, FIGS. 4 and 5 show a second embodiment of the present invention corresponding to claims 1 and 2. FIG. That is,
This example shows a case where a cold-shrinkable tube 5a having a straight connection portion as shown in FIG. 9 is manufactured by the manufacturing method of the present invention. Especially in the case of this example, the core 9
As b, a simple cylinder having no injection hole or the like inside is used. Instead, in the case of this example, the operation of injecting the insulating rubber for forming the insulating cylindrical portion 6a through the injection hole 24a provided at the end of the tubular element 21a for forming the external semiconductive layer 8a. To be able to do. Injection hole 2 provided at the end of the tubular element 21a
As the shape of 4a, an appropriate shape such as a circular hole described in the upper part of FIG. 5, a concave groove having a semicircular cross section also shown on the right side, a concave groove having a crescent cross section also shown on the left side can be adopted. Except for the difference in the structure of the injection port for injecting the insulating rubber, it is the same as the case of the above-described first example, and the description of the equivalent parts will be omitted.

Next, FIGS. 6 to 8 show a third embodiment of the present invention corresponding to claims 1 and 3. FIG. This example shows a case of manufacturing a pre-molded insulator 14a constituting a prefabricated connection portion as shown in FIG. 13 by the manufacturing method of the present invention. In the completed state of the pre-mold insulator 14a, as shown in FIG.
The circumference of one half in the axial direction of a (the right half in FIG. 8) is covered with a semiconductive layer 19a made of semiconductive rubber. On the other hand, around the other half of the insulating layer 18a in the axial direction (the left half in FIG. 8), the outer surface coating layer 2 made of the same insulating rubber as the insulating layer 18a is formed.
Covered by 5.

In order to manufacture the pre-molded insulator 14a having such a structure, first, a rubber-like cylindrical member is formed in the middle of a core 9a similar to that used in the first example. The tubular element 21b is fitted outside. In particular,
In the tubular element 21b used in this example, one half in the axial direction is a semiconductive portion 26 made of semiconductive rubber, and the other half in the axial direction is an insulating portion 27 made of insulating rubber. Such a tubular element 21b is made of a semiconductive part 2 which is made separately.
6 and the insulating portion 27 are butted against each other, and this butted portion is cross-linked and fused. The semiconductive part 26
Both the insulating part 27 and the insulating part 27 can be manufactured at low cost, similarly to the above-described tubular element 21 of the first example.

When such a tubular element 21b is externally fitted to the core 9a, the periphery of the tubular element 21b is covered with a mold 22a. The mold 22a also has a two-part structure in which a pair of elements each formed in a semi-cylindrical shape are butted, like the mold of the first example described above. In the above core 9
A cavity 23a for forming the pre-mold insulator 14a is formed between the cavity 23a and the outer peripheral surface of the cavity a. That is, the shape of the inner peripheral surface of the mold 22a is
4a substantially (the pre-molded insulator 14
(a) if elastic deformation and heat shrinkage during processing are ignored.

As described above, the tubular element 21b is externally fitted to the core 9a, and
b is covered with the mold 22a, between the inner peripheral surface of the tubular element 21a and the outer peripheral surface of the core 9a,
The insulating rubber material as another polymer material is replaced with the core 9a.
It is injected through an injection hole 24 provided therein. With this injection, as shown in FIG. 7, the tubular element 21b is
The air existing in the cavity 23a is expanded while being exhausted through an exhaust hole (not shown). Therefore, the injection of the insulating rubber material while expanding the tubular element 21b is continued until the outer peripheral surface of the tubular element 21b is in close contact with the inner peripheral surface of the mold 22a as shown in FIG. Further, by this injection, the pressure in the cavity 23a is increased to a desired pressure.

As described above, if the insulating rubber material is injected until the outer peripheral surface of the tubular element 21b comes into close contact with the inner peripheral surface of the mold 22a and the pressure in the cavity 23a reaches a desired value. For example, the injection of the insulating rubber material is stopped, and the insulating rubber material is cured by heating (vulcanization) or the like. As a result, the insulating rubber material and the insulating portion 27 of the tubular element 21b are in contact with the insulating layer 1
8a is connected to the semiconductive portion 2 of the tubular element 21b.
6 constitute the semiconductive layers 19a, respectively.

After the insulating rubber material is sufficiently cured to form the insulating layer 18a, the core 9a is pulled out from the inside of the insulating layer 18a and the end of the semiconductive layer 19a. . The insulating layer 18a
The insulating rubber cured in the injection hole 24 is cut off at the downstream end opening portion of the injection hole 24. Therefore, fine irregularities are formed on the inner peripheral surface of the intermediate portion of the insulating layer 18a. However, since this portion is not a portion that requires particularly strict characteristics in terms of maintaining the electrical characteristics of the prefabricated connection portion, no particular problem occurs. On the other hand, the downstream end opening of the injection hole 24 is close to the end of the insulating layer 18a where the end of the semiconductive layer 19a is exposed on the inner peripheral surface of the pre-mold insulator 14a. If it is installed in a portion, a problem is likely to occur in terms of maintaining the electrical characteristics.

In this embodiment, the semiconductive tube 20 (see FIG. 3) is obtained by changing the cylindrical member made of a polymer material for connecting a power cable from a cold-shrinkable sleeve 5a (see FIG. 3) to a pre-molded insulator 14a. 1 to 4), and the configuration is the same as that of the first example described above except that the shape of each part is changed. Also, the work of injecting the insulating material for producing the pre-mold insulator 14a is performed through the injection hole formed at the end of the tubular element 21b as in the second example shown in FIGS. You can also do.

[0030]

The method of manufacturing a cylindrical member made of a polymer material for connecting a power cable according to the present invention is constructed and operates as described above. It can be performed efficiently without using expensive molds. Therefore, it is possible to reduce the cost of the cylindrical member made of the polymer material for connecting the power cable.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an initial step of a first example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the same intermediate step.

FIG. 3 is a sectional view of the same final step.

FIG. 4 is a sectional view showing a second example of the embodiment of the present invention in a state of a final step.

FIG. 5 is an end view seen from the left side of FIG. 4;

FIG. 6 is a sectional view showing an initial step of a third example of the embodiment of the present invention.

FIG. 7 is a sectional view showing the same intermediate step.

FIG. 8 is a sectional view of the same final step.

FIG. 9 is a cross-sectional view showing an example of a straight-line connection portion of a power cable using a cold-shrinkable tube to which the present invention is applied.

FIG. 10 is a half-cut side view showing only the cold-shrinkable tube taken out.

FIG. 11 is a half-cut side view showing a state before a core is extracted from a cold-shrinkable tube manufactured by a conventional manufacturing method.

FIG. 12 is a sectional view for explaining a conventional manufacturing method in the order of steps.

FIG. 13 is a half-cut side view showing an example of a prefabricated connection portion of a power cable using a pre-molded insulator to which the present invention is applied.

FIG. 14 is a half-cut side view showing only the pre-mold insulator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power cable 2 Cable conductor 3 Cable insulator 4, 4a Connection sleeve 5, 5a Cold-shrinkable tube 6, 6a Insulating cylinder part 7, 7a Internal semiconductive layer 8, 8a External semiconductive layer 9, 9a, 9b Core 10 Conductor fixture 11 Reinforced insulator 12 High voltage shield electrode 13 Case 14, 14a Pre-molded insulator 15 Spring 16 Inner diameter tapered surface 17 Outer diameter tapered surface 18, 18a Insulating layer 19, 19a Semiconductive layer 20 Semiconductive tube 21 , 21a, 21b Tubular element 22, 22a Mold 23, 23a Cavity 24, 24a Injection hole 25 Outer surface coating layer 26 Semiconductive part 27 Insulating part 28 Pressing sleeve

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F204 AA45 AB13 AD05 AD12 AD35 AH34 EA03 EB12 EK13 EK24 5G355 AA03 BA01 BA15 CA06 CA09 CA23 5G375 AA02 BA26 BB43 CA02 CA14 CB07 CB19 CB38 CB53 DB32

Claims (3)

[Claims] 1. A cylindrical member made of a polymer material for power cable connection, which is formed entirely of a polymer material into a cylindrical shape and is formed by laminating an outer layer on the outer peripheral surface of an inner layer over the entire circumference. ,
From the state in which the tubular element formed of a polymer material having elasticity in a cylindrical shape is externally fitted to the core and the periphery of the tubular element is covered with a mold, the inner peripheral surface of the tubular element and the core are removed. After injecting another polymer material between the outer peripheral surface and expanding the tubular element, the other polymer material is solidified, and the outer layer is formed by at least a part of the tubular element in the axial direction. A method for producing a cylindrical member made of a polymer material for connecting a power cable, wherein the inner layers are each made of the different polymer material. 2. The tubular member made of a polymer material for connecting a power cable is a cold-shrinkable tube, and the tubular element comprises:
Made of semiconductive polymer material over the entire length,
After fitting a cylindrical semi-conductive tube made of semi-conductive polymer material for constituting the internal electrode to the middle part of the core and covering the core and the semi-conductive tube with a tubular element 2. The polymer material for an electric power cable according to claim 1, wherein another polymer material having an insulating property is injected between an outer peripheral surface of the core and the semiconductive tube and an inner peripheral surface of the tubular element. A method for manufacturing a tubular member. 3. The tubular member made of a polymer material for connecting a power cable is a pre-molded insulator, and the tubular element is
A part in the axial direction is made of a semiconductive polymer material, and the remainder is made of an insulating polymer material, and injected between the inner peripheral surface of the tubular element and the outer peripheral surface of the core. The method for producing a polymer material cylindrical member for a power cable according to claim 1, wherein the other polymer material has an insulating property.