JPH05174936A - Method for forming cable connecting portion reinforcing insulator - Google Patents

Abstract

PURPOSE:To prevent a foreign material from intruding through a changeover valve by eliminating provision of a changeover valve in a filling path for making a reinforcing insulator of a resin material in a cable connecting portion in treating the connecting portion of a cable such as a CV cable used in a high voltage transmission cable line. CONSTITUTION:In a molding portion of a reinforcing insulator for covering the connecting portion of a CV cable, a space 12 in conformity with a shape of the reinforcing insulator is formed inside a metal mold 10, and such a means is used as to press-fill crosslinked polyethylene or the like into the space 12 for solidification. In order to fill the resin material, a resin filling short tube 40 is fixed to the metal mold 10, and resin is supplied to the resin filling short tube from an extruder via a flexible filling tube 30. Resin is filled in the connecting portion between the resin filling short tube 40 and the flexible filling tube 30 by the use of a connecting means such as a box nut 42. After that, the resin filling short tube is crushed so as to form a closed portion, or the resin remaining inside the resin filling short tube is cooled for solidification so as to form a plug made of resin. Consequently, it is possible to maintain a pressure inside the metal mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for covering a connection portion of a plastic insulated cable in a cave or a manhole at a cable construction site, and a plastic material for forming a reinforced insulator is extruded into the mold. Using an extruder for
The present invention relates to an improvement in a method of forming an extrusion-molded reinforced insulator on the connection portion.

[0002]

2. Description of the Related Art Crosslinked polyethylene insulated cable (hereinafter C
A plastic insulated cable represented by (V cable) is used for a 275 kV power transmission line,
When laying in a cave etc., connect long ones in sequence,
The power transmission path is configured. Therefore, the CV
When laying a cable, conductors are connected in a cave or at a manhole, and the connection is covered with a plastic material and a means for forming an insulating coating. There is. To connect the CV cable, for example, a device as disclosed in Japanese Patent Publication No. 63-37469 is used.

In the apparatus shown in the above-mentioned conventional example, an apparatus in which an extruder and a mold are combined is arranged in a cave or a manhole which is a connecting work portion of a CV cable, and the apparatus is placed in a clean room environment. A mechanism is provided that operates in a state where dust and the like do not enter, and covers the periphery of the connection portion of the CV cable by extrusion. Also, for example, in a three-phase AC high-voltage power transmission path, it is necessary to form similar reinforcing insulators for three CV cables, and therefore, for each of the three-phase CV cables, a reinforcing insulator must be formed. In order to continuously perform the forming work of the
It is also practiced to use a device as disclosed in Japanese Patent Laid-Open No. 198074.

As described above, as a device for forming a reinforced insulator at a connection portion of a CV cable, a device having a mechanism as shown in FIG. 11 is generally used.
It is placed inside a clean room and is used in an environment where dust and other harmful substances do not enter from the outside. In the conventional example shown in FIG. 11, in order to form the reinforcing insulator 5 with respect to the connection portion of the CV cables 1 and 1a, a mold 10 having a split shape is used. An adapter 11 matching the outer shape of the reinforcing insulator 5 is arranged inside, and an electric heater 13 is arranged around the mold. Then, the conductor 2 of the connecting portion of the CV cable 1 is connected by the conductor connecting pipe 3 to the inner semiconductive layer 4 in advance.
The one formed with is positioned inside the mold 10,
A plastic material is injected into the space portion 12 of the adapter 11 and solidified to form a reinforcing insulator.

A flexible injection pipe 30 and a switching valve 3 for supplying a plastic material to the mold 10.
It is connected to the extruder 20 via 1 and the injection pipe 35. The extruder 20 is configured to be movably mounted on a trolley 21. A motor drive device 25 is arranged with respect to the extrusion device 22, and a plastic material supplied from a hopper 23 is extruded. At 22, the liquid is extruded from the extrusion head 24 as a high-pressure fluid and injected into the mold through the flexible injection pipe 30. Further, a pressure sensor 14 and a pressure gauge 15 are arranged in the mold,
The pressure of the plastic material injected into the space 12 of the mold 10 is monitored, and the injection work is controlled.

In the pouring device as shown in FIG. 11, the switching pipe 31 is arranged between the pouring pipe 35 attached to the mold 10 and the flexible pouring pipe 30. The switching valve 31 is configured as shown in FIGS. 12 and 13, and connects the flexible injection pipe 30 and the injection pipe 35 and the discharge pipe 36 to the main body 32 of the switching valve 31, The valve member 33 is provided so as to rotate inside the valve main body 32 to form a three-way valve. Further, the valve member 33 is provided with a substantially L-shaped hole 33a, one of the shafts is supported by the main body by a nut 34, and a handle is provided on the other shaft 33b of the valve to switch the valve. Is configured as follows.

In the device shown in FIG. 11, the CV
When forming the reinforcing insulator at the connection portion of the cable 1, first, a colorless polyethylene resin compound containing no cross-linking material is accommodated in the hopper 23, and the switching valve 31 is switched to the discharge pipe 36, and the extrusion device is used. The inside of the pipe and the switching valve is cleaned using the resin fluidized by 22. After that, after confirming that dust or the like is not mixed in the discharge path, the colored polyethylene resin compound mixed with the cross-linking material is inserted into the hopper 23, and the resin is fluidized by the extrusion device 22 to be extruded. To Then, the tip end of the fluidized resin material is discharged from the discharge pipe 3
After confirming that the pressure reaches 6, the valve is switched and the resin is injected into the space of the mold 10 through the injection pipe 35. Further, when performing the resin injection work, the mold 1
0 is heated to a predetermined temperature by the electric heater 13 to maintain the temperature of the injected resin, and the space 12
Allow the resin to fill.

As described above, when the material forming the reinforcing insulator is injected, the pressure inside the mold is adjusted by the pressure gauge 15.
When the pressure rises to a constant value and the space is filled with resin, the switching valve 31 is switched,
Excess resin is discharged from the discharge pipe 36. Further, in order to prevent the resin containing the cross-linking agent from solidifying in the extrusion device 22, the extrusion head 24 and the pipe path, when the extrusion work is completed, the resin not containing the cross-linking material is extruded,
Fill the inside of each device. Then, with respect to the resin injected into the mold, with the injection pipe 35 closed, the electric heater 13 arranged around the mold is turned off and solidified by cooling, and the CV cable is connected. The reinforcing insulator 5 is formed on the portion.

[0009]

As described above, in the conventional extrusion device, the three-way switching valve is used to form the reinforcing insulator at the connecting portion of the CV cable, and the injection of the resin material and the It is adapted to work such as cleaning the inside of pipes. Then, after injecting the resin material into the reinforced insulator forming portion, the valve is closed to maintain the pressure of the resin filled inside the mold, and at the time of cooling the mold, an extra amount is required. It should be possible to prevent the application of pressure. Therefore, when the resin forming the reinforced insulator is cooled and solidified, the pressure inside the mold is kept constant so as to cope with the shrinkage that occurs when the resin is cooled.

However, it is necessary to dismantle the switching valve after injecting the resin and clean the inside, and in this disassembling step, it is necessary to pay close attention to prevent foreign matter from entering the inside. Therefore, the worker is required to have the skill. Further, in order to prevent foreign matter from adhering to the inside of the pipe or the switching valve, it is necessary to set a condition where there is no dust inside the clean room for performing work. There is also the problem that the management of the clean room is troublesome. If a defect occurs in the handling of the switching valve, dust or the like will be mixed into the resin material that constitutes the reinforced insulator, and the insulation performance will not be exhibited satisfactorily, resulting in problems such as characteristic deterioration and dielectric breakdown accidents. May occur, and serious defects may occur in the high voltage transmission line.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the conventional molding apparatus for a reinforced insulator, and enables resin injection without using a switching valve and facilitates the work of closing the injection pipe. The purpose is to provide a method that can be performed.

[0012]

SUMMARY OF THE INVENTION The present invention provides a mold for covering a connecting portion of a plastic material insulated cable in a cave or a manhole at a cable construction site, and a reinforcing insulator formed in the mold. It relates to a method for forming an extrusion-molded reinforced insulation on the connection using an extruder for extruding a plastic material. In the present invention, a resin injection short pipe is connected to the mold, and a plastic material is injected into the mold from an extruder through the short pipe,
After the injection of the plastic material is completed, the short tube is closed by means of crushing, and after the plastic material in the mold is solidified, the short tube is removed from the mold.

Further, in the present invention, cooling means is arranged at a predetermined portion of the short pipe, and after the injection of the plastic material is completed, the short pipe is closed by means for crushing the short pipe, and the closed portion is forced by the cooling means. It is possible to apply a method of removing the short tube from the mold after the plastic material is solidified by solidifying the plastic material in the mold by cooling by mechanical cooling. Further, in the present invention, after the injection of the plastic material is completed, a recess is formed in the short tube by the pressing means, and the plastic material housed in the recess is solidified by natural cooling or forced cooling to form a plug, It is also possible to use a method of removing the short tube from the mold after the plastic material injected into the mold has solidified.

In addition to the above construction, in the present invention, a short resin injection pipe (short resin injection and resin stopping pipe) provided in the mold is connected to a flexible injection pipe provided in the extruder to be fluidized. It is also possible to construct a supply path for the plastic material and connect these short pipes and the injection pipe with a cap nut or the like.

As described above, in the method for forming a reinforcing insulator of a cable connecting portion of the present invention, an injection pipe is formed without arranging a switching valve in the injection pipe for injecting resin into the mold. Since the means for directly connecting the short pipe for resin injection is used, the structure of the resin injection pipe can be simplified and the operation of the device can be facilitated. Also, since no switching valve is used, there is no need to perform cleaning work on the conventional switching valve, dust and the like can be prevented from entering the resin injection pipe line, and resin can be injected into the mold for reinforcement. The work of forming the insulator can be easily performed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus for applying the method for forming a reinforced insulator for a cable connecting portion according to the present invention will be described with reference to the illustrated example. The apparatus shown in FIG. 1 is a simplified illustration of an apparatus having substantially the same configuration as the apparatus shown in FIG. 11, but in the present invention, as will be described later, the extruder 20 has The short tube 40 for resin injection is directly connected to the flexible injection tube 30 to be connected, and an apparatus having a structure not using a switching valve is configured. In the device shown in FIG. 1,
As shown in FIG. 11, the conductors are connected to the connecting portions of the CV cables 1 and 1a, and an internal semiconductive layer is formed on the connecting portions. A mechanism for forming a reinforced insulator by cross-linked polyethylene is fixed to the connection part.

Further, in order to inject the resin into the mold, an extruder 20 composed of an extrusion device 22, a drive device 25 and an extrusion head 24 is arranged. Then, in the extruder 20, a resin material is supplied from a hopper 23 arranged with respect to the extrusion device 22, the resin fluidized at high pressure is discharged through the extrusion head 24, and the resin injection short is injected from the extrusion head 30. It is adapted to be extruded into a mold through a tube 40. As the device 30, a metal pipe or a rubber pipe having flexibility and pressure resistance can be used. In the apparatus of the present invention, a clean room portion is provided inside a cave or a manhole at the construction site of the CV cable, and resin injection work can be performed inside the room.

The portion for injecting the resin material into the mold 10 is constructed as shown in detail in FIG.
In the example shown in FIG. 2, the short tube for resin injection 40 is connected to the extrusion head 30 by using a cap nut 42, and the other end of the short tube for resin injection 40 has a screw portion 41.
It is attached to the mold via. As the short pipe 40 for resin injection, a stainless pipe can be used as in the case of the conventional injection pipe, and has a strength sufficient to withstand the pressure applied to the resin. I am making it. In addition, since the resin injection short pipe 40 is discarded after one injection work, 50 to 100
Although it is configured to have a length of about mm, it is necessary to make the length sufficient to cope with the action of compressing to form the closed portion, as described later.

In the apparatus of the present invention constructed as described above, as in the case of the apparatus shown in FIG. 11, at the first stage of the work, the resin such as polyethylene containing no crosslinking agent is discharged from the extruder 20. After extruding and confirming that there is no foreign matter inside the extruding device 22 and the flexible injecting tube 30, the resin mixed with the cross-linking agent is sent out and injected into the mold. As described above, when the work of injecting the resin into the mold and forming the reinforcing insulator in the CV cable is completed, the short tube 40 for injecting the resin is placed in the short tube 40 for injecting resin as in the case of the conventional switching valve. It needs to be closed,
Since the injection pipe line of the present invention has no switching valve, it is necessary to press the short pipe for resin injection to form the closed portion.

Therefore, in the present invention, means for forming the closing portion 45 in the short resin injection pipe 40 by the pressing device 50 as shown in FIG. 3 is used. In the example shown in FIG. 3, as the pressing device 50, a convex die 51 and a concave die 53 are arranged so as to face each other, and a convex portion of the convex die and a concave portion of the concave die are made to face each other, and a driving not shown is performed. The mechanism is used to apply the action of pressing from both sides of the short tube for resin injection 40, and the closed portion 45 is formed by the concave portion 46 and the convex portion 47 formed on the short tube for resin injection 40. ing.

Then, as described above, by forming the closing portion 45 for the resin injection short pipe, the same operation as in the case of the switching valve can be exhibited. That is, after injecting the resin material into the reinforcing insulator forming portion of the mold 10, the valve is closed to maintain the pressure of the resin filled inside the mold and to cool the mold. Is
It should be possible to prevent excessive pressure from being applied.
Further, when the resin forming the reinforcing insulator is cooled and solidified, the pressure inside the mold is kept constant to form a closed portion so as to cope with the contraction that occurs during the cooling of the resin. Can be

As shown in FIG. 3, instead of using the method of forming the closed portion 45 by the concave portion 46 and the convex portion 47 formed on the resin injection short pipe 40, In the present invention, it is also possible to use a method of forming a closed portion by using a pressing device as shown in FIG. 4 or 5. In the example shown in FIG. 4, the pressing device 50
Is made up of two convex dies 51 and 52, and the resin injection short pipe 40 is pressed by the convex portions from both sides, and the recessed portions 46 and 46a formed in the resin injection short pipe 40 close the pipeline. Let them do it. Further, in the example shown in FIG. 5, the short tube 40 for resin injection is bent to form the bent portion 4
8, the means for forming the closed portion 45 is used.

In order to apply the means for forming the closed portion as shown in FIG. 3 to FIG. 5, in the resin injection short pipe 40 of the present invention, as shown in FIG. The thin portion 43 can be formed at a position where the pressing device is operated with respect to the tube 40. In addition, as shown in FIG. 7, a portion where a process for facilitating the pressing work is performed on the short pipe for resin injection, for example, a portion where a part of a metal pipe is annealed or the like is provided. A mark 44 or the like can be provided to the portion that has been formed and subjected to such treatment so that the work of forming the closed portion can be easily performed.

As described above, in the present invention, the short section 40 for injecting the resin is subjected to a treatment such as crushing, so that the closing portion 45.
By using the method of maintaining the pressure of the resin material injected into the mold by forming the resin, a slight gap remains by only forming the mechanically crushed part of the resin injection short pipe. There is a fear of doing it. Therefore, in the present invention, as shown in FIG. 6, the cooling device 55 can be arranged corresponding to the closed portion. And
After physically forming the closed portion, a cooling device 55 is provided corresponding to the closed portion of the short tube for resin injection, and the resin material remaining in the short tube for resin injection is solidified in the pipe, and is plugged with the resin. Can also be formed.

Further, in the present invention, it is also possible to apply the means as shown in FIG. 8 or FIG. 10 without using the means for completely crushing the resin injection short pipe by the pressing device. In the example shown in FIG. 8, the short tube 4 for resin injection is used.
0 using a pressing device 50 as shown in FIG. 4,
Relatively shallow recesses 46 and 46a are formed in the resin injection short pipe 40 by using convex dies 51 and 52, and a small diameter portion 49 is formed by the recesses. Next, as shown in FIG. 9, a cooling device 55 is arranged on the small-diameter portion 49 to apply a cooling action to form plugs P made of solidified resin on the upper and lower portions of the small-diameter portion 49, Be able to close the injection tube (short tube).

Further, in the present invention, in addition to the means shown in FIG. 8 described above, as shown in FIG. 10, a pressing device 50a using convex dies 51a and 52a provided with two convex portions on the upper and lower sides is applied. It is possible to form the two small diameter portions 49, 49a at a predetermined interval with respect to the resin injection short pipe 40. Then, the cooling device 55 as shown in FIG. 9 is provided for the portion divided by the two small diameter portions.
Can be arranged to form the plug P made of the solidified resin, and the effect of closing the injection pipe (short pipe) can be exhibited well. As described above, by forming the plug of the solidified resin in the inside of the short tube for resin injection, in the present invention, the resin injected into the mold can be used without using the switching valve. The function of maintaining the pressure and the function of reducing the pressure when the resin forming the reinforcing insulator is solidified can be corresponded.

In each of the above-described embodiments, as the cooling device 55, it is possible to use a means for forcibly blowing air with a fan or the like, or a cooling means with water, etc. As in the case, it is also possible to use means for blowing cold air. The resin in the short pipe for resin injection is rapidly solidified by applying a cooling action to the small diameter portion formed in the short pipe for resin injection by the cooling device, and the resin formed in the short pipe for injection resin is formed. The injection pipe (short pipe) can be closed with a resin by using the plug P.

Further, in the injection apparatus of the present invention, a metal having good thermal conductivity, such as copper or other metal, can be used as the short tube 40 for resin injection, and processing by a pressing device can be performed as compared with stainless steel. And the cooling effect can be improved. Furthermore, the short tube for resin injection of the present invention is removed from the mold and discarded after one use, and a means for attaching a new short tube for resin injection to the mold may be used each time it is used. Therefore, it can be used for injecting a resin material as in the case of a conventional injection pipe attached to a mold. In the present invention, it is not necessary to clean the switching valve after injecting the resin material into the mold, so that the step of forming the reinforcing insulator can be simplified.

In the embodiment of the present invention, only when the flexible injection pipe and the resin injection short pipe are directly connected between the extruder and the mold and the resin material is injected into the mold, I am explaining. However, in the present invention, it is possible to use a pipe member having no flexibility in place of the flexible injection pipe. Furthermore, without using these pipe members, only the short pipe for resin injection and the mold are extruded. It is possible to place it between the machine and the machine. And in any of the above cases,
By making it possible to configure the closing portion for the short pipe for resin injection, it is possible to omit the use of the switching valve and simplify the configuration of the device.

[0030]

As described above, the method for forming a reinforced insulator for a cable connecting portion according to the present invention is configured as described above, so that a switching valve is arranged on an injection pipe for injecting resin into a mold. Without using the means for directly connecting the short pipe for resin injection and resin stopping, it is possible to simplify the configuration of the resin injection pipe line and facilitate the operation of the device. it can. Further, since the switching valve is not used, it is not necessary to perform the cleaning work for the conventional switching valve, and the step of injecting the resin material into the molded portion of the reinforcing insulator can be simplified. Furthermore, in the present invention, it is possible to prevent dust and the like from entering the resin injection pipe line through the switching valve and the connection portion of the switching valve, and to prevent dust and the like from entering the inside of the reinforcing insulator. .. Therefore, according to the present invention,
A cable connection portion with stable electrical performance can be obtained at low cost without causing problems such as deterioration of characteristics and accidents of dielectric breakdown due to the inclusion of dust or the like inside the reinforced insulator.
It is useful as a cable connection.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an apparatus of the present invention.

FIG. 2 is a cross-sectional view showing a resin injection system provided in a mold.

FIG. 3 is an explanatory view of a means for forming a closed portion on the short tube for resin injection.

FIG. 4 is an explanatory view of another embodiment of means for forming a closed portion.

FIG. 5 is an explanatory view of another embodiment of means for forming a closed portion.

FIG. 6 is an explanatory diagram in the case where thin wall processing is performed on a short tube for resin injection.

FIG. 7 is an explanatory diagram of a case where a marker is provided on a bent portion of a short tube for resin injection.

FIG. 8 is an explanatory diagram of a case where a small-diameter portion is formed on a resin injection short tube.

9 is an explanatory view of a means for forming a resin plug with respect to the means shown in FIG.

FIG. 10 is an explanatory view of another embodiment of a mechanism for forming a resin plug on a short tube for resin injection.

FIG. 11 is an explanatory view of a device for forming a reinforced insulator on a conventional cable connecting portion.

FIG. 12 is an explanatory diagram of a conventional example in which a die is provided with a switching valve.

FIG. 13 is an exploded perspective view of a conventional switching valve.

[Explanation of symbols]

1 CV cable, 5 reinforced insulator, 10
Mold, 13 Electric heater, 20 Extruder, 22 Extrusion device, 24 Extrusion head, 30 Flexible injection pipe,
31 switching valve, 35 injection pipe, 40 short pipe for resin injection, 42
Cap nut, 45 closing part, 49 small diameter part, 50 pressing device, 55 cooling device.

Claims (3)

[Claims] 1. A mold for covering a connecting portion of a plastic material insulating cable in a cave or a manhole at a cable construction site, and an extruder for extruding a plastic material for forming a reinforced insulator into the mold. In the method of forming an extrusion mold type reinforced insulator on the connection part using, a short tube for resin injection is connected to the mold, and a plastic is injected from the extruder into the mold through the short tube. A cable characterized by injecting a material, closing the short tube by means of collapsing the short tube after the injection of the plastic material, and removing the short tube from the mold after the plastic material in the mold has solidified. A method for forming a reinforced insulator at a connection part. 2. A cooling means is arranged at a predetermined portion of the short pipe, and after the injection of the plastic material is completed, the short pipe is closed by means for crushing the short pipe, and the closed portion is forcibly cooled by the cooling means. The method for forming a reinforced insulator of a cable connecting portion according to claim 1, wherein a plug made of a plastic material is formed, and after the plastic material in the mold is solidified, the short tube is removed from the mold. 3. A pressing means is arranged at a predetermined portion of the short pipe, and after the injection of the plastic material is completed, a recess is formed in the short pipe by the pressing means, and the plastic material housed in the recess is naturally cooled or forced. The reinforcing insulation of the cable connection portion according to claim 1, wherein the short tube is removed from the mold after the plastic material in the mold is solidified by cooling to solidify the plastic material in the mold. Method.