JPH0351852Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an apparatus for manufacturing a crosslinked polyethylene cable.

Conventionally, in the production of cross-linked polyethylene cables, the core wire is coated with an insulating material and then introduced into a cross-linking tube (cap), where the core wire is heated by induction and insulated via high-temperature, high-pressure gas from outside the insulation coating. The layer was heated to cause a crosslinking reaction. This crosslinking reaction generates decomposition gas, which causes the insulation coating to foam and create voids, so high-pressure gas was applied.

However, in the conventional manufacturing means, since the decomposition gas was not actively removed, it was difficult to suppress the generation of voids, and as a result, it was not possible to increase the manufacturing speed of the cable.
Furthermore, since the insulating layer is deformed when the induction heating coil comes into contact with the high-temperature, softened coating, a predetermined clearance is maintained between the insulating layer and the induction coil to ensure that they never come into contact.

Therefore, the inner diameter of the induction heating coil becomes larger than necessary, resulting in a decrease in heating efficiency.

An object of the present invention is to provide a crosslinked polyethylene cable manufacturing apparatus that can improve extrusion crosslinking speed and performance.

The gist of this invention is an extruder that coats an insulating material around a core wire that is being towed and advances, a high-frequency induction heating coil that is supplied with high-frequency current to heat the core wire, and a cap that is heated from the outside using high-temperature, high-pressure gas. In an apparatus for manufacturing a crosslinked polyethylene cable, which is provided with a means for heating and the above-mentioned mouthpiece for guiding the coated insulating part extruded by the extruder, the mouthpiece is formed of a porous sintered alloy material, and the mouthpiece itself is made of a porous sintered alloy material. It is characterized in that a soft resin coating layer is applied to the inner surface of the mouthpiece, and a suction/exhaust port for decomposed gas during the crosslinking reaction is provided on the outer periphery of the mouthpiece.

Hereinafter, an embodiment of the crosslinked polyethylene cable manufacturing apparatus of the present invention will be described with reference to FIGS. 1 and 2.

Reference numeral 2 denotes an extruder which extrudes an insulating material around the core wire 1 which is being towed and advances in the vertical direction to form a cable sheath 8. Reference numeral 5 designates the extruder 2 for extruding a sintered alloy body made of a porous material with a long land, and is formed long in the direction in which the cable sheathing 8 and the guide reel advance. A spout 3 is provided so that lubricating oil passes through the mouthpiece 5 and is poured onto the coating layer interface. The external heating surface 11 on the outer periphery of the cap 5 has a temperature of 1 to 20K.
An induction coil 7 for high-frequency induction heating to which a high-frequency current of Hz is supplied is wound in multiple turns, and the external heating surface 11 is heated by heating means (not shown) using high-temperature and high-pressure gas. There is. A communication port 1 is provided between the outer periphery of the cap 5 and the external heating surface 11.
A spacer 12 having a diameter of 3 is provided, and a suction/exhaust port 9 is provided on the external heating surface 11 .

6 is a cable covering with a soft resin coating 8
The cable is formed so that it can slide smoothly without clogging the fine holes on the surface of the cap 5. Therefore, its thickness can be reduced by applying a vacuum from the suction/exhaust port 9 to the cable sheath 8. 0.03 to 0.2 through which the generated decomposition gas can pass relatively easily
It needs to be about mm. 4 is an isolator.

The cap 5 is made of a porous sintered alloy such as stainless steel or bronze, but since the heating induction coil 7 is attached to the outside of the cap 5, this portion is also heated unnecessarily.

Therefore, in order to reduce the amount of heating, it is desirable to use a material with high electrical resistivity, and the resistivity p is p>
Approximately 100μΩcm is preferable. However, even if p is less than that, the efficiency of conductor induction heating simply decreases and there is essentially no effect. In addition, the induction coil 7 includes a plurality of transposed twisted wires formed by insulating each strand, arranged and accommodated in a ring shape around the inner periphery of a non-magnetic high electrical resistivity pipe, and the transposed twisted wires arranged in an annular shape. Induction heating efficiency can be improved by using a high-frequency induction heating coil in which a cooling water passage is formed in the center of the wire group.

When manufacturing a cross-linked polyethylene cable using this manufacturing equipment, the core wire 1 traveling in the vertical direction
An extruder 2 extrudes an insulating material around the cable to form a cable sheath 8, and the cable sheath 8 is advanced through the base 5. Since the core wire 1 traveling inside the base 5 is heated by the induction coil 7, the cable sheathing 8 is heated from the inner circumferential side, and the external heating surface 11 is heated by high-temperature, high-pressure gas to heat the cable sheathing 8 from the outer circumference. By heating from the side, the cable sheath 8 is heated to about 180° C. to the center to effect crosslinking. In this case, the decomposed gas generated during crosslinking of the cable sheathing 8 is evacuated and forcibly sucked through the suction/exhaust port 9, and the gas that has diffused to the outer peripheral surface of the cable sheathing 8 is dispersed through the porous cap 5. It is possible to prevent the generation of voids and increase the production speed.

It should be noted that it takes a considerable amount of time for the cable sheathing 8 to be heated by heating from the inside and outside, and decomposition gas is generated after the cable sheathing 8 is heated and the crosslinking reaction has progressed. The exhaust may be exhausted from a position where the cable has advanced to some extent in the direction of travel. Further, it is preferable to heat the cap 5 from the oil filler port 3 and heat the cable sheath 8 from the front as much as possible.

As a result of degassing the cracked gas as described above,
In the case of manufacturing a 66KV, 400mm ² cross-linked polyethylene cable, compared to using conventional manufacturing equipment of this type, the 3μm voids were reduced by 1/10, the density was improved somewhat, and the cable sheath 8 was completely gel-based. Rate is
There was no problem at 85% or higher, and the AC breakdown voltage was the same as the conventional value, but the impulse breakdown value increased by 20%,
The extrusion production speed has been doubled compared to the conventional method.

As described above, the crosslinked polyethylene cable manufacturing apparatus of the present invention has the effect of significantly improving extrusion manufacturing speed and performance.

[Brief explanation of drawings]

FIG. 1 is a front view showing a part of an embodiment of the crosslinked polyethylene cable manufacturing apparatus of the present invention in cross section, and FIG. 2 is a detailed sectional view of section A in FIG. 1. 1... core wire, 2... extruder, 5... nozzle, 7...
...Induction coil, 8...Cable covering, 9...Suction/exhaust port.

Claims (1)

[Scope of utility model registration request] an extruder that coats an insulating material around the core wire that is being towed and advances, a high-frequency induction heating coil that is supplied with a high-frequency current to heat the core wire, a means for heating the cap from the outside with high-temperature, high-pressure gas, and the above-mentioned A cross-linked polyethylene cable manufacturing apparatus is provided with the above-mentioned cap for guiding the coated insulating part extruded by an extruder, and the above-mentioned cap is formed of a porous sintered alloy material, and the inner surface of the cable is coated with a soft resin. 1. An apparatus for manufacturing a crosslinked polyethylene cable, characterized in that a crosslinked polyethylene cable is coated with a layer and a suction/exhaust port for decomposed gas during a crosslinking reaction is provided on the outer periphery of the base.