JPS62133608A - Manufacture of rubber and thermoplastic insulated cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method of manufacturing a rubber or plastic coated cable by crosslinking it by radiant heating.

``Prior art'' Conventionally, dry crosslinking involves extrusion coating an uncrosslinked insulating mixture such as rubber or plastic onto a core wire, and continuously crosslinking the extrusion coated cable by radiant heating in an inert gas atmosphere while running it in a crosslinked pipe. This method is adopted as the manufacturing number for high voltage cables, but this is because the cross-linked pipe wall is heated to a high temperature of 300 to 450°C and the heat capacity of the cross-linked pipe is large, so it is difficult to run the cable and operate the extrusion covering machine. Even if the continuous cross-linking is stopped by stopping the radiant heating heater, the cross-linked pipe will still remain heated for 1 to 2 hours, and the cable remaining inside the cross-linked pipe will have foaming or swelling in the coating. It could not be used because it caused softening and sagging.

Therefore, in order to quickly lower the temperature of the cross-linked pipe, a method for manufacturing rubber and plastic cables is proposed, as disclosed in Japanese Patent Publication No. 57-19532, which uses a blower to circulate inert gas inside the cross-linked pipe for forced cooling when cross-linking is stopped. It was known.

``Problems to be Solved by the Invention'' As mentioned above, the method of forced cooling by circulating an inert gas can prevent the occurrence of foaming and softening of the cable coating, but it can also prevent uncrosslinked cables remaining in the crosslinked pipes. Since the cable is cooled without completing heating crosslinking, there is a problem that the cable becomes unusable, resulting in large losses and high manufacturing costs.

Therefore, the present invention provides a method for manufacturing a cable in which such loss does not occur.

"Means for Solving the Problems" In order to solve the above-mentioned 1M point, the present invention feeds a cable core wire with a dummy wire connected to the end to an extrusion coating head, and insulates at least an internal conductive layer on this core wire. The uncrosslinked coating of the coating layer is extruded, and the cable is run through a radiant heating zone consisting of a plurality of divided heating zones to remove the uncrosslinked coating from the IJO.
a first step of thermally crosslinking, and then a second step of ceasing extrusion of the insulating coating layer but extruding an inner conductive layer onto the dummy wire when the end of the core wire of the cable reaches the extrusion coating head; step, and then a third step of sequentially stopping the heating of the heater in each of the plurality of divided heating zones when the end of the core wire of the running cable passes through the plurality of divided heating zones in sequence; A fourth step of reducing the pressure in the cross-linked pipe by stopping the running of the cable and the dummy wire and the extrusion of the internal conductive layer to the dummy wire when the end of the core wire comes near the end seal of the cooling zone of the cross-linked pipe.
The cable is manufactured by a method consisting of the following steps.

"Function" By extruding and coating the internal conductive layer on the dummy wire in the second step, leakage of pressure inside the crosslinked pipe from the twisting gap of the dummy wire or the gap with the nipple is prevented, and the pressure inside the crosslinked pipe is reduced. In the third step, the end of the cable core wire stops unnecessary heating by sequentially stopping heater heating in the plurality of divided heating zones, and in the fourth step, when the cable stops running, the end of the cable core wire is in the heating zone. Since only the dummy wire is left and the cable is not left behind, the covering is no longer exposed to residual heat from the cross-linked pipe and no softening occurs.

“Actual 1 scary case” Embodiments of the present invention will be described below with reference to the drawings.

- Apparatus used in the method of the invention.

In the figure, 1 is an extrusion coating head for extruding three layers, 11 forms an extrusion coating with an internal conductive (or semiconductive) layer, 12 forms an extrusion coating with a rubber or brass insulating coating layer, and 13 forms the extruded MW of the outer conductive (or semiconductive) layer. 2 is a crosslinked pipe, 3 is a radiant heating zone formed in the front stage of the crosslinked pipe near the extrusion coating head, and 4 is a cooling zone formed in the rear stage of the crosslinked pipe 2.

The radiant heating zone 3 is composed of a plurality of divided zones by arranging a plurality of heaters 5 for radiant heating in the longitudinal direction on the outer periphery of the crosslinked pipe.
A divided heating zone 51, a second divided heating zone 52, a third divided heating zone 53, and a fourth divided heating zone 54 are installed in this order, and each divided heating zone independently controls the temperature and on/off of the heater 5. Configure it so that you can.

Although the drawings show four divided heating zones, this number can be set as appropriate, and N2 gas for pressurization is sealed in the cross-linked pipe.

The crosslinked pipe of the cooling zone 4 is filled with cooling water 6,
An end seal 7 for preventing leakage of cooling water is provided at the end of the bridge pipe to provide a liquid seal. In the drawing, the cooling zone 4 is shown with the intermediate portion omitted.

:Method of the present invention: To manufacture a cable using the continuous crosslinking apparatus configured as described above, a dummy wire B having a diameter approximately equal to or slightly smaller than the diameter of the core wire A is connected to the terminal end of the cable core wire A. Connect at part O and feed this core wire to the bridge pipe. Note that this dummy wire B is made of twisted steel wire or other appropriate wire.

, 1st step: First, the cable core wire A is fed to the extrusion coating head 1 to apply extrusion coating, and is run through the crosslinked pipe z to perform heating crosslinking. The uncrosslinked coatings of the semiconductive (or semiconductive) layer 11, the rubber plastic insulating coating layer 12, and the external conductive (or semiconductive) layer 13 are extruded and run in the crosslinked pipe 2 and in the radiant zero heat zone 3. This makes the first radiant zone 3 constituting the radiant zero heat zone 3. , the uncrosslinked extruded coating is crosslinked by radiation heating by all the heaters in the second, third, and fourth divided heating zones. At this time, the outer periphery of the heat-crosslinked coating is pressurized with pressurized N2 gas sealed in the crosslinked pipe, so that foaming is prevented. The heated and cross-linked cable D then travels through the cooling zone 4, is cooled, advances from the end seal 7 to the outside of the cross-linked pipe, and is wound around a drum.

:Second step: The cable D, in which the core wire A has been extruded and crosslinked as described above, runs in the crosslinked pipe, and the connecting portion C of the end of the core wire A with the dummy wire B is connected to the extrusion coating head 1. When reaching , extrusion of the insulating coating layer 12 and the outer conductive (or semiconductive) layer 13 is stopped. ``When the connecting part C reaches the extrusion coating head 1'' in @ means when the connecting part C comes just before the extrusion coating head 1, or while passing through the extrusion coating head 1, or when the connecting part C reaches the extrusion coating head 1. The optimum case is immediately after passing through the extrusion coating head 1.

When the extrusion of the insulating coating layer 12 and the external conductive (or semiconductive) layer 13 to the cable D is stopped in this way, the extrusion coating head is connected to the connection point C at the terminal end of the core wire A of the cable D with the above-mentioned coating applied. The dummy wire B included in the dummy wire B is extruded and coated with only the internal conductive (or semiconductive) layer 11 to a thickness of approximately XW. This prevents the pressurized N2 gas in the cross-linked pipe 2 from leaking out of the cross-linked pipe through the twisting gap of the gummy wire B or the gap between the nipple in the extrusion coating head 1 and the dummy wire B, and A pressurized state can be maintained.

, Third step: When the dummy wire B is coated with extrusion and moves through the crosslinked pipe as described above, the terminal end of the core wire A of the cable D connected in front of the dummy wire B is heated by radiation. First divided heating zone 51, second divided heating zone 52, third divided heating zone 53, fourth divided heating zone 5 of zone 3
4 will be passed in sequence. Therefore, if the terminal end of the core wire A passes through the first divided heating zone 51, this first
Then, as the cable D continues to advance and the end of its core wire A passes through the second divided heating zone 52, the heating of this second heater is stopped, and then the cable When D further advances and the terminal end of the core wire A sequentially passes through the third divided heating zone 53 and the fourth divided heating zone 54, the heating of the third and fourth heaters is sequentially stopped.

Note that each of the first, second, third, and fourth heaters may be stopped when each divided heating zone is arranged short.

Even if the heating of the heater is stopped immediately after the end of the core wire A of the cable D coated with the above-mentioned extrusion coating passes through each divided heating zone, the coating has already been sufficiently heated, so cross-linking will not occur. will be carried out satisfactorily.

:Fourth step: When the end of the core wire A of the cable D coated with the extrusion coating as described above moves through the cross-linked pipe z and approaches the end seal 7 at the end of the cooling zone 4, the above-mentioned step is performed. Cable D
Then, the running of the dummy wire B connected to the terminal end of the core wire A is stopped, and the extrusion of the conductive layer 11 to the dummy wire B is also stopped, the line is temporarily stopped, and the pressure inside the bridge pipe 2 is reduced. This pressure reduction is performed by releasing the M2 gas sealed in the cross-linked pipe to open the inside of the cross-linked pipe 1 to atmospheric pressure, or to reduce the pressure to a pressure higher than atmospheric pressure but considerably lower.

Next, the bare dummy wire B, which has not been coated with the conductive coating described above, is started running again, and the end of the cable D, whose core wire A has been coated with an extrusion coating, is sealed with the end seal 7 of the cooling section. Let Roke Sasa t go 4fR, bridge pipe 2
The cable D is not present within the radiant heating zone 3, and only the dummy wire B is present at least in the radiant heating zone 3.

The present invention manufactures a rubber or plastic coated cable by the method described above, and after completing the heating crosslinking of the cable D, the crosslinked pipe 2 that has stopped heating is left as it is for a long time, but the residual heat remains in the crosslinked pipe. Even if this continues, the cable D is not present in the cross-linked pipe, so the extruded coating of the cable will not soften or sag due to the residual heat of the cross-linked pipe, unlike in the conventional case. In addition, since the dummy wire B remaining in the cross-linked pipe receives residual heat from the cross-linked pipe, the conductive coating on the dummy wire near the connection point C becomes soft, but the conductive coating when the dummy wire is reused The work of stripping off the coating becomes easy, and since the conductive coating covering this dummy wire portion is thin, there is little loss of material.

According to experiments, the cable core diameter is 19s17B, the inner conductive layer thickness is 0.8], the insulation layer thickness is 11.2 times, and the outer conductive layer thickness is o. In manufacturing the 571+1 66KV, 250SQ cable, the heating zone was divided into four divided heating zones, each of which was controlled independently in temperature, and a steel wire of the same diameter was used as a dummy wire at the rear end of the cable core wire. They were connected and manufactured using the following steps.

First, when the tip of the steel wire of the dummy wire passed through the extrusion coating head, extrusion coating of the insulating layer and the outer conductive layer was stopped.

Then, each time the rear end of the cable core passed through the four divided heating zones, the heaters in the respective divided heating zones were turned off one after another.

The line was then stopped when the rear end of the cable core came near the outlet of the bridge pipe. Then, the N2 gas sealed in the bridge pipe was released. At this time, no foaming or the like occurred in the internal conductive layer covering the steel wire of the dummy wire. Then, only the dummy steel wire was run again, so that only the bare steel wire was present in the heating zone.

When manufactured in the manner described above, a good cable could be manufactured.

"Effects of the Invention" As described above, the present invention consists of a radiation heating zone provided in a cross-linked pipe consisting of a plurality of divided heating zones, and a dummy wire is connected to the terminal end of the cable core wire to be fed to the cross-linked pipe. In the process, the extrusion of the insulation coating layer is stopped when the end of the cable core wire reaches the extrusion coating head, which saves insulation coating material, and the inner conductive layer is extruded onto the dummy wire, reducing the twisting gap of the dummy wire. In the third step, when the end of the cable core passes through the divided heating zones in sequence, the heater heating of each divided heating zone is stopped in sequence. This prevents unnecessary heating, and in the fourth step, when the cable running and extrusion coating are stopped to complete continuous crosslinking, only the dummy wire is present in the tta heating zone. Therefore, the cable sheathing does not undergo foaming or softening and sagging, and the cable does not become unusable, and manufacturing costs can be reduced.

[Brief explanation of drawings]

The drawing shows a crosslinking device used in one embodiment of the method of the invention. 1゛Extrusion coating head 2: Cross-linked pipe 3: Radiant heating zone 4'' Cooling zone 5: Heater 51: First divided heating seam〉' 52: Second divided heating zone 53: Third divided heating zone 54: Fourth divided heating Zone 6: Cooling water 7゛End seal A: Core wire B: Dummy wire O: Connection part D: Cable patent applicant
Representative of Furukawa Electric Co., Ltd. Patent attorney Oka 1) Kikuji (and others 1)
given name)

Claims (1)

[Claims] A cable core wire with a dummy wire connected to the terminal end is fed to an extrusion coating head, and a cable with an uncrosslinked coating of at least an internal conductive layer and an insulating coating layer extruded on the core wire is run inside a crosslinked pipe, and this cable is A first step of thermally crosslinking the uncrosslinked coating by running it through a radiant heating zone constituted by divided heating zones, and then, when the end of the core wire of the cable reaches the extrusion coating head, the insulation coating layer is heated and crosslinked. a second step in which extrusion is stopped but the inner conductive layer is extruded onto the dummy wire; and then, when the end of the core wire of the running cable passes sequentially through the plurality of divided heating zones, the dividing is performed in sequence. A third step of sequentially stopping the heating of the heater for each heating zone, and then, when the end of the cable core wire comes near the end seal of the cooling zone of the bridge pipe, running of the cable and dummy wire and internal conduction to the dummy wire is performed. A method for manufacturing a rubber or plastic coated cable, comprising a fourth step of stopping extrusion of the layer and reducing the pressure inside the crosslinked pipe.