JP2013070459A - Rubber unit for power cable connection and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the removal of rubber injection parts and burrs after an internal semiconductive layer is molded and limit a region on a surface of the internal semiconductive layer which is roughened by polishing to a small area, thereby achieving the reduction of the manufacturing cost and stabilizing electric performance.SOLUTION: In a rubber unit for power cable connection is formed by integrally molding an internal semiconductive layer 1, semiconductive stress cone parts 2A, 2B, a reinforcement insulation layer 3, and an external semiconductive layer 4, the internal semiconductive layer 1 is divided into two pieces in the axial direction to form two semiconductive cylindrical members 1A, 1B. This structure reduces the size of a mold, rubber injection parts, burrs, and a polishing range. The two semiconductive cylindrical members 1A, 1B have outer peripheral surfaces, each of which is formed into a taper shape so that the inner end side is thinner than the outer end side.

Description

  The present invention relates to a cylindrical rubber unit used for linear connection of a plastic insulated power cable such as a CV cable, and a manufacturing method thereof.

  A conventional power cable connecting rubber unit is shown in FIG. This rubber unit is formed by integrally molding an inner semiconductive layer 1 made of silicone rubber, ethylene propylene rubber or the like, semiconductive stress cone portions 2A and 2B, a reinforcing insulating layer 3 and an outer semiconductive layer 4. The inner diameter of the rubber unit is set to be smaller than the outer diameter of the insulating layer of the power cable to be connected, and the reinforcing insulating layer 3 is brought into close contact with the cable insulating layer by the surface pressure due to the difference in diameter to ensure the insulating performance of the connecting portion. To do. The inner semiconductive layer 1 is a portion that has an intermediate portion located on the cable conductor connecting portion and both end portions located on the cable insulating layer to alleviate concentration of the electric field on the high voltage side. The semiconductive stress cone portions 2A and 2B are located on the outer periphery from the cable external semiconductive layer to the cable insulating layer, and are portions for relaxing the concentration of the electric field on the low voltage side.

This rubber unit is manufactured as follows (see Patent Documents 1 to 3).
1) The semiconductive rubber material is injected into a mold and heated and pressed to mold the internal semiconductive layer 1 and the semiconductive stress cone portions 2A and 2B.
2) The rubber injection part and the burr | flash part which were formed at the time of shaping | molding of the internal semiconductive layer 1 and the semiconductive stress cone part 2A, 2B are grind | polished and removed.
3) By setting the polished inner semiconductive layer 1 and semiconductive stress cone portions 2A and 2B in a reinforcing insulating layer molding die, injecting an insulating rubber material into the die and heating and pressurizing, The reinforcing insulating layer 3 is formed.
4) The rubber injection part and the burr | flash part which were formed at the time of shaping | molding of the reinforcement insulating layer 3 are grind | polished and removed.
5) By setting a mold for forming an external semiconductive layer on the outside of the reinforcing insulating layer 3, injecting a semiconductive rubber material into the mold and heating and pressurizing (or by applying a semiconductive paint) The outer semiconductive layer 4 is formed.
The outer semiconductive layer 4 is formed before the reinforcing insulating layer 3 is formed in the same manner as the inner semiconductive layer 1 and the semiconductive stress cone portions 2A and 2B, Can also be set.

Japanese Patent Laid-Open No. 11-332081 JP 2001-268769 A JP 2004-274913 A

  Since the power cable connecting rubber unit is used at a high voltage, there is a risk of dielectric breakdown starting from the foreign matter when foreign matter is mixed in, and it is necessary to take sufficient measures to prevent foreign matter from entering during manufacturing. In particular, since the surface of the inner semiconductive layer has a high electric field, it is necessary to pay close attention to the adhesion of foreign substances.

  The internal semiconductive layer must be polished after molding in order to remove the rubber injection part and burrs. However, if the internal semiconductive layer becomes large, the expansion of the rubber in the mold will cause the mold to join the mold. Not only does the resulting burr become thicker and it becomes difficult to remove the polishing, but in order to fill the rubber into every corner of the mold, it is necessary to make the rubber injection part thick or provide multiple rubber injection parts As a result, there is a problem that polishing removal becomes difficult and polishing takes time.

  Further, since the polished surface is left with minute irregularities, and polishing residue or the like tends to adhere thereto, it tends to be an electrical weak point. In addition, in order to prevent electrical weak points, the polishing finish must be carefully performed, and the internal semiconductive layer must be carefully cleaned, resulting in a problem that the molding time becomes long. Yes.

  In view of the above problems, the object of the present invention is to make it possible to easily remove a rubber injection portion and burrs after molding an internal semiconductive layer, and to reduce a region where the surface of the internal semiconductive layer is roughened by polishing. An object of the present invention is to provide a power cable connecting rubber unit that can reduce the manufacturing cost and stabilize the electric performance, and a manufacturing method thereof.

  To achieve the above object, the present invention provides a rubber unit for connecting a power cable, in which an internal semiconductive layer, a semiconductive stress cone portion, a reinforcing insulating layer, and an external semiconductive layer are integrally formed. Is formed of a plurality of semi-conductive cylindrical members by dividing in the axial direction.

  In the present invention, of the plurality of semiconductive cylindrical members, the two semiconductive cylindrical members forming the end portion of the inner semiconductive layer have an outer peripheral surface so that the inner end side is thinner than the outer end side. It is preferably formed in a tapered shape. Here, the inner end side means the central side in the axial direction of the power cable connecting rubber unit, and the outer end side means the end side in the axial direction.

  In the present invention, the adjacent semiconductive cylindrical members can be arranged with their end surfaces in contact with each other or bonded with a semiconductive rubber adhesive.

  In the present invention, the adjacent semiconductive cylindrical members are arranged with a gap between the end faces, and a part of the reinforcing insulating layer is inserted into the gap or the end faces are bonded with an insulating rubber adhesive. You can also.

  The method for manufacturing a power cable connecting rubber unit according to the present invention is a method for manufacturing a power cable connecting rubber unit in which an internal semiconductive layer, a semiconductive stress cone portion, a reinforcing insulating layer, and an external semiconductive layer are integrated. The inner semiconductive layer is divided into a plurality of axially divided inner semiconductive layers and formed as a plurality of semiconductive cylindrical members, and each of the semiconductive cylindrical members has a mold opening direction in the axial direction. It is characterized by forming using a mold which is

  According to the present invention, the inner semiconductive layer is divided into a plurality of axially divided inner semiconductive layers, and is configured by a plurality of semiconductive cylindrical members. Is significantly smaller than the conventional internal semiconductive layer, so that the rubber injection portion can be reduced in size and the burr can be reduced in thickness. For this reason, the polishing time for removing the rubber injection part and burrs can be shortened, and the cleaning time at the time of forming the reinforcing insulating layer can be shortened. Moreover, since the area | region where the surface of an internal semiconductive layer is roughened by grinding | polishing can be made small, an electrical weak point becomes difficult to generate | occur | produce. Therefore, the manufacturing cost of the rubber unit can be reduced and the electrical performance can be stabilized.

  In addition, if a semiconductive cylindrical member constituting the internal semiconductive layer is molded using a mold whose mold opening direction is the axial direction, the burrs that can be formed on the dividing surface of the mold are in the circumferential direction. Polishing for removing the burrs of the cylindrical member can be performed by a rotary polishing machine, so that complicated manual polishing is not required, and further labor saving of the polishing work can be achieved.

Sectional drawing which shows one Example of the rubber unit for power cable connection which concerns on this invention. Sectional drawing which shows the metal mold | die which shape | molds the semiconductive cylindrical member for internal semiconductive layers of the rubber unit of FIG. Sectional drawing which shows the other Example of the rubber unit for electric power cable connection which concerns on this invention. Sectional drawing which shows the further another Example of the rubber unit which concerns on this invention. Sectional drawing which shows the further another Example of the rubber unit which concerns on this invention. Sectional drawing which shows the further another Example of the rubber unit which concerns on this invention. Sectional drawing which shows the further another Example of the rubber unit which concerns on this invention. Sectional drawing which shows the conventional rubber unit for electric power cable connection.

  Example 1 FIG. 1 shows an example of the present invention. This power cable connecting rubber unit is formed by integrally forming the inner semiconductive layer 1, the semiconductive stress cone portions 2A and 2B, the reinforcing insulating layer 3 and the outer semiconductive layer 4. Is characterized in that it is divided into two in the axial direction and is composed of two semiconductive cylindrical members 1A, 1B. The two semiconductive cylindrical members 1A and 1B have the same shape and the same size, and the outer peripheral surface is tapered so that the inner end side is thinner than the outer end side. More specifically, the outer ends of the semiconductive cylindrical members 1A and 1B are formed in a convex curved surface, and a position slightly on the inner end side from the outer end becomes the maximum outer diameter portion D having the largest outer diameter. Yes. And it is a taper surface where an outer diameter becomes small gradually from this largest outer diameter part D toward an inner end side. With such a shape, both the electric field around the D portion and the electric field at the central portion of the inner semiconductive layer 1 can be lowered.

  The two semiconductive cylindrical members 1A and 1B are arranged with their inner end surfaces in contact with each other. The two semiconductive cylindrical members 1A and 1B may have their inner end surfaces bonded to each other with a semiconductive rubber adhesive. In order to bond the two semiconductive cylindrical members 1A and 1B, when the two semiconductive cylindrical members 1A and 1B are set on a mandrel used for forming the reinforcing insulating layer 3, the semiconductive cylindrical members are formed. What is necessary is just to adhere | attach the inner end surfaces of member 1A, 1B with an adhesive agent. As the semiconductive rubber-based adhesive, a semiconductive rubber forming a semiconductive layer may be used.

  The semiconductive cylindrical members 1A and 1B can be formed by a mold as shown in FIG. The mold 5 includes a mold member 5A for molding the inner peripheral surface of the semiconductive cylindrical members 1A and 1B, and a mold member 5B for molding the outer peripheral surface, and a plane perpendicular to the central axis is divided. It is a surface P and is not divided in the axial direction. The mold opening direction of the mold 5, that is, the direction in which the mold members 5 </ b> A and 5 </ b> B are separated in order to take out the molded product (semiconductive cylindrical member) is the axial direction.

  When the semiconductive cylindrical members 1A and 1B are molded with such a mold 5, burrs are generated on the outer peripheral surfaces of the semiconductive cylindrical members 1A and 1B in the circumferential direction. Therefore, the polishing operation can be performed easily and with high accuracy by a rotary polishing machine. In addition, since the semiconductive cylindrical members 1A and 1B are about half the length of the conventional one, the mold 5 may be much smaller than the conventional one that forms the integral internal semiconductive layer 1 and is generated. It is possible to suppress the burr to be thin.

  Conventionally, when manufacturing an internal semiconductive layer, a mold whose plane including the central axis is a dividing surface, that is, a mold that opens in a direction perpendicular to the central axis is used. There is a problem in that burrs are generated in the axial direction on the surface of the surface, and a careful polishing operation by a skilled worker is required to remove the burrs, which increases the manufacturing cost. However, the present invention can solve this problem.

  The dividing surface P of the mold 5 is provided at the location of the maximum outer diameter portion D of the semiconductive cylindrical member 1A (1B). Therefore, in this embodiment, the dividing surface P is located at a position slightly closer to the inner end side than the outer end of the semiconductive cylindrical member 1A (1B). In the power cable connecting rubber unit 1, the portion where the maximum outer diameter portion D of the semiconductive cylindrical member 1A (1B) of this embodiment is located can be designed so that the electric field density is low. There is an advantage that the accuracy required for the work of removing burrs generated on the dividing surface P of the mold 5 can be relaxed.

  <Embodiment 2> FIG. 3 shows another embodiment of the present invention. This power cable connecting rubber unit has an internal semiconductive layer 1 divided into two in the axial direction and is composed of two semiconductive cylindrical members 1A and 1B. The two semiconductive cylindrical members 1A and 1B are arranged with a gap between the inner end faces, and the reinforcing insulating layer 3 is formed so as to enter the gap between the semiconductive cylindrical members 1A and 1B. It is. Even in such a configuration, the semiconductive cylindrical members 1A and 1B are electrically connected via the conductor connecting portion, so that the gap does not become an electrical weak point.

  The two semiconductive cylindrical members 1A and 1B are formed by insulating rubber between the inner end faces when the two semiconductive cylindrical members 1A and 1B are set on a mandrel used for forming the reinforcing insulating layer 3. You may adhere | attach with a system adhesive.

  Since the configuration other than the above is the same as that of the first embodiment, the same parts as those in FIG.

  <Embodiment 3> FIG. 4 shows still another embodiment of the present invention. In this power cable connecting rubber unit, two semiconductive cylindrical members 1A and 1B are formed in a straight tube shape (constant inner and outer diameters). Since the other configuration is the same as that of the first embodiment, the same parts as those in FIG.

  <Embodiment 4> FIG. 5 shows still another embodiment of the present invention. In this power cable connecting rubber unit, the two semiconductive cylindrical members 1A and 1B are formed in a straight tube shape (constant inner and outer diameters). Since the other configuration is the same as that of the second embodiment, the same parts as those in FIG.

  <Embodiment 5> FIG. 6 shows still another embodiment of the present invention. In the power cable connecting rubber unit, the outer peripheral surfaces of the two semiconductive cylindrical members 1A and 1B are formed in a tapered shape so that the outer end side is thinner than the inner end side. Since the other configuration is the same as that of the second embodiment, the same parts as those in FIG. Also in this case, the two semiconductive cylindrical members 1A and 1B may be arranged with their inner end surfaces in contact with each other or bonded with a semiconductive rubber adhesive.

<Example 6> Although the example which divided | segmented the internal semiconductive layer 1 into 2 was shown in the above-mentioned Example, the internal semiconductive layer 1 may be divided | segmented into 3 or more in this invention.
The power cable connecting rubber unit shown in FIG. 7 is obtained by dividing the inner semiconductive layer 1 into five parts. That is, the inner semiconductive layer 1 is composed of five semiconductive cylindrical members 1C, 1D, 1E, 1F, and 1G. Among these, the semiconductive cylindrical members 1C and 1G form the end of the internal semiconductive layer 1, the semiconductive cylindrical member 1E forms the center of the internal semiconductive layer 1, The remaining semiconductive cylindrical members 1 </ b> D and 1 </ b> F form between the end portion and the central portion of the internal semiconductive layer 1.

The two semiconductive cylindrical members 1C and 1G forming the end of the inner semiconductive layer 1 have the same shape, and the outer peripheral surface is tapered so that the inner end side is thinner than the outer end side. Yes. More specifically, the outer ends of the semiconductive cylindrical members 1C and 1G are formed in a curved surface, and the position on the inner end side slightly from the outer end is the maximum outer diameter portion D having the largest diameter. And it becomes a taper surface where an outer diameter becomes small gradually toward the inner end side from this largest outer diameter part D.
The semiconductive cylindrical member 1E that forms the central portion of the inner semiconductive layer 1 has a cylindrical shape with a substantially uniform outer diameter and a small thickness.
The remaining semiconductive cylindrical members 1D and 1F are tapered on the outer peripheral surface so that the inner end side is thinner than the outer end side. Specifically, the outer diameters of the outer ends of the semiconductive cylindrical members 1D and 1F are the same as the outer diameters of the inner ends of the semiconductive cylindrical members 1C and 1G. The outer diameter of the inner ends of the semiconductive cylindrical members 1D and 1F is the same as the outer diameter of the end portion of the semiconductive cylindrical member 1E at the center.

  Also in this case, the semiconductive cylindrical members may be arranged with their end surfaces in contact with each other or bonded with a semiconductive rubber-based adhesive. Since the other configuration is the same as that of the first embodiment, the same parts as those in FIG.

1: Internal semiconductive layer 1A, 1B: Semiconductive cylindrical member 2A, 2B: Semiconductive stress cone part 3: Reinforcing insulating layer 4: External semiconductive layer 5: Mold 5A, 5B: Mold member

Claims (5)

  In a power cable connecting rubber unit formed by integrally forming an internal semiconductive layer, a semiconductive stress cone portion, a reinforcing insulating layer, and an external semiconductive layer, the internal semiconductive layer is divided into a plurality of semi-conductors by dividing the internal semiconductive layer in the axial direction. A power cable connecting rubber unit comprising a conductive cylindrical member.   Two semiconductive cylindrical members forming the end of the inner semiconductive layer among the plurality of semiconductive cylindrical members are formed with a tapered outer peripheral surface so that the inner end side is thinner than the outer end side. The rubber unit for connecting a power cable according to claim 1.   3. The rubber unit for connecting a power cable according to claim 1 or 2, wherein the adjacent semiconductive cylindrical members are disposed with their end surfaces in contact with each other or bonded with a semiconductive rubber adhesive. .   Adjacent semi-conductive cylindrical members are arranged with a gap between the end faces, and a part of the reinforcing insulating layer is inserted into the gap or the end faces are bonded with an insulating rubber adhesive. The rubber unit for connecting a power cable according to claim 1 or 2, characterized in that   In the method of manufacturing a power cable connecting rubber unit in which an internal semiconductive layer, a semiconductive stress cone part, a reinforcing insulating layer, and an external semiconductive layer are integrated, the internal semiconductive layer is divided in the axial direction to form a plurality of semiconductive layers. A rubber unit for connecting a power cable, characterized in that it is molded as a conductive cylindrical member, and each semiconductive cylindrical member is molded using a mold whose opening direction is the axial direction. Production method.

Images