JPS60138806A - Method of feeding cable conductor of oblique continuous bridging device - 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] The present invention provides an inclined continuous cross-linking device for cables. It concerns the method of feeding cable conductors.

△ (Prior technology) Conventionally, a cable conductor is coated with an uncrosslinked insulating material by extrusion, filled in a crosslinked pipe, and then continuously crosslinked by running through a heat medium and heating the uncrosslinked insulation from the outer periphery to form a rubber plastic insulated cable. W! In order to shorten the crosslinking speed, the cable conductor fed to the extrusion coating machine is preheated, and the cable conductor is preheated by electrical heating or high frequency induction heating. Although it is preheated, when heating with electricity, approximately 2 of the conductor diameter
In order to conduct electricity by contacting an electrode ring with a diameter of 0 to 30 times the cable conductor, as the diameter of the conductor increases, the diameter of the electrode ring also becomes significantly large, which is impractical. f. When performing high-frequency induction heating, as shown in Figure 5, the heating efficiency e decreases as the diameter of the high-frequency induction heating coil becomes larger compared to the diameter 6 of the cable conductor running inside it. Therefore, heating efficiency is better if the coil is made smaller in diameter and brought closer to the running cable conductor, but if the coil is made smaller in diameter, there is a risk that the cable conductor running inside will come into contact with the coil.

For this reason, it is desirable for the high-frequency induction heating coil to be close to the cable conductor without making contact with the cable conductor, and to make the diameter as small as possible, but the locus that the cable conductor travels not only fluctuates and is not necessarily constant; Since the coil needed to heat the conductor to a sufficient preheating temperature is over 1 m long, it is extremely difficult to install a long coil with a small diameter so that it does not come into contact with the cable conductor whose running trajectory fluctuates. In continuous cross-linking equipment where the cross-linked pipe is installed at an angle, the trajectory of the cable running inside the cross-linked pipe becomes catenary-like due to the cable's own weight, so the cross-linked pipe is also installed in a catenary shape, and the extrusion coating machine The capstan that feeds the cable conductor will also be installed on the catenary trajectory.
In order to prevent the cable conductor running in a catenary trajectory from coming into contact with the high-frequency induction heating coil, it is possible to install the coil along the catenary trajectory, but it is extremely difficult to install the coil in this way. , the diameter of the coil must be made large, and on the other hand, if the diameter of the fill becomes large, the heating efficiency will decrease, so the length of the coil must be made long, and the catenary-shaped cable conductor will not come into contact with this long coil. In order to achieve this, the diameter of the coil had to be made larger and larger.0Also, when a molten metal salt is used as a heat medium, the specific gravity of the molten metal salt is large, so The cable passing through the high-frequency induction heating coil floats up and the catenary trajectory of the cable conductor fluctuates.In order to prevent the cable conductor from coming into contact with the high-frequency induction heating coil, the diameter of the coil must be made extremely large. I had to make it the diameter.

Thus, the traditional method of preheating the cable conductor feeding into the extrusion coating machine by high frequency induction heating coil has low heating efficiency, so that the crosslinking rate is effectively shortened.
When heated above 0°C, the cable conductor had the disadvantage of oxidation and discoloration.

Additionally, water vapor or other substances may adhere to the surface of the cable conductor that is fed through the capstan to the extrusion sheathing machine. When coated, it creates voids, so such deposits on the surface of the cable conductor must be removed before being sent to the extrusion coating machine. There was.

(Object of the Invention) In view of the above-mentioned points, the present invention provides an inclined cable continuous cross-linking device that improves the heating efficiency of a high-frequency induction heating filter for preheating a cable conductor to be fed to an extrusion coating machine, and
A method for feeding a cable conductor is provided that prevents oxidation of the heated cable conductor.

(Structure of the Invention) FIG. 1 is a diagram for explaining one embodiment of the present invention, in which 1 is a crosshead of an extrusion coating machine in an inclined type continuous cable cross-linking device, and 2 is a crosshead of an extrusion coating machine. A cross-linked pipe whose starting end is connected to the head 1 of the machine and installed in a catenary-like inclination, W is a cable conductor fed onto the extrusion coating machine, 3 is a mail, and 5 is its high frequency power source.

The cable conductor W is connected to the above-mentioned high frequency induction IJ [ ] thermal coil 4
As it travels through the pipe, it is preheated by high-frequency induction heating and fed to the head 1 of an extrusion coating machine, where it is extruded and coated with uncrosslinked insulating material and enters the crosslinked pipe 2.

This uncrosslinked extruded sheathed cable is heated and crosslinked from the outer periphery in the heating section filled with a heat medium in the crosslinked pipe 2, but the cable conductor W inside the sheath is preheated to a high temperature as described above. Therefore, the innermost layer of the coating is also heated to a sufficient crosslinking temperature by the high temperature cable conductor W and is completely crosslinked.

The cable running in the bridge pipe 2 runs in a catenary-like trajectory, and the cable conductor W fed to the head 1 of the extrusion coating machine is also fed along the catenary-shaped trajectory. The extension line of the catenary locus is like the broken line X in FIG.

In the inclined cable continuous cross-linking device as described above,
The present invention is directed to a catenary-shaped running locus of a cable conductor W exiting from the high-frequency induction heating coil 4 and traveling toward the head 1 of the extrusion coating machine between the high-frequency induction heating filter 4 and the head 1 of the extrusion coating machine. A guide roll 6 is installed, and while the cable conductor W runs from this guide roll 6 toward the head 1 of the extrusion coating machine, the cable conductor W runs along a catenary-shaped running trajectory, and from the capstan 3 to the above-mentioned guide roll 6. The cable conductor W runs in a straight line along the straight line connecting the capstan 3 and the guide roll 6. With this configuration, the high frequency induction heating coil 4 can be made small in diameter. Even if the cable conductor W is placed close to the cable conductor W running inside the cable conductor W,
does not come into contact with the coil 4, thus making it possible to increase the efficiency of induction heating of the cable conductor W.

Furthermore, the present invention provides a method for preventing oxidation of the cable conductor W which passes through the high-frequency induction heating coil 4 and is fed to the head 1 of the extrusion coating machine via the guide roll 6 even if it is inductively heated to a high temperature. A cylindrical body 7 for preventing oxidation is provided to enclose the cable conductor running path. This oxidation prevention cylinder 7 has one end connected to the head 1 of the extrusion coating machine, a cable conductor passing hole 8 provided at the other end, the above-mentioned high frequency induction heating coil 4 and guide roll 6 installed inside, and nitrogen gas. It is filled with an inert gas 49, where 9 is a seal attached to the passage hole 8, and 10 is a gas feed pipe.

With the above configuration, the cable conductor W is induction heated by the high frequency induction heating coil 4 in the oxidation prevention cylinder 7 filled with the inert gas, and is sent to the head 1 of the extrusion coating machine via the guide roll 6. 160°
It will not oxidize or change color even when heated to temperatures higher than C or higher.

In addition, by supplying and circulating an inert gas from the gas supply pipe 10 into the oxidation prevention cylinder 7 and exhausting it from the gap between the seal 9 and the cable conductor W, it is possible to prevent the gas from adhering to the surface of the cable conductor. Clean cable conductors without any moisture on the surface are fed to the head 1 of the extrusion coating machine and extrusion coated. This prevents the occurrence of voids in the coating due to deposits on the surface of the cable conductor.

When the cable conductor W fed to the head 1 of the extrusion coating machine runs at a high linear speed and must be heated to a high temperature, the effective length of the high frequency induction heating coil along the cable conductor W is lengthened. In addition to the above-mentioned high-frequency induction heating coil 4, a second high-frequency induction heating coil 4'' is added as shown in the first figure, and both coils 4.4'' are installed in a straight line. In this case, in addition to the guide roll 6 mentioned above, there is also a guide roll 6 between the two fills 4 and 4' as shown in the figure.
1, and then capstan 3 and second coil 4'
A guide roll 62 is also installed between the guide rolls 6 and 6.
1 holds the cable conductor W between both coils 4 and 4' from above, and the guide roll 62 supports the cable conductor W coming out of the capstan 3 from below, so that it is sent from the capstan 3 to the head 1 of the extrusion coating machine. The supplied cable conductor W is made to run in a straight line.

In this way, even if both coils 4.4' are made small in diameter and brought close to the cable conductor W, the running cable conductor W will not come into contact with the fill 4.4', increasing the efficiency of induction heating of the cable conductor W. .

The above-mentioned high-frequency induction heating coil is wound around the outer peripheral surface of the support tube f71 made of a non-magnetic material, and the cable conductor W is run inside this support tube, but there is no space between the conductor W and the coil-wound support tube. The gap is much smaller than the gap of 20 or more wings in the case of a conventional heating filter, and about 61 wings is sufficient. This high frequency induction heating coil and guide roll 6 are
Instead of installing them in a common oxidation prevention cylinder 7 as shown in the first figure, they are installed separately in a coil cylinder 71 and a guide roll box 72, respectively, as shown in the second figure. 73 may be connected to the head 1 of the extrusion coating machine, and guide rolls 6 may be installed above and below the cable conductor W. Also, the oxidation-preventing cylinder may be made of a non-magnetic material, and the outer periphery of the non-magnetic cylinder may be It is also possible to wrap a high frequency induction heating coil around the second surface.

11 shown in the first diagram is a temperature measuring device for the cable conductor W;
A temperature sensor is installed at the lower end of a rod that penetrates the cylinder wall of the oxidation prevention cylinder 7 near the extrusion coating machine head 1 through a packing, and the temperature sensor is brought into contact with the running cable conductor W and heated by a high-frequency induction heating coil. The temperature of the cable conductor W is detected, and the output of the high frequency power supply section 5 of the high frequency induction heating coil is controlled based on the detected output. This temperature measuring device 11 is equipped with guide bars 12 on both sides of the running cable conductor W so as not to come off as shown in the third figure, or by attaching guide bars 12 to prevent vibrations of the running cable conductor W as shown in the fourth figure. A contact plate 14 may be provided via an absorbing spring 13. By using such a humidity measuring device 11, it becomes possible to constantly monitor the temperature of the cable conductor W running inside the oxidation-preventing cylinder 7 and perform appropriate temperature control.

(Effects of the Invention) As described above, the present invention provides an inclined continuous crosslinking device in which a high-frequency induction heating coil 4 is installed between the extruder head 1 and the capstan 3, and the high-frequency induction heating coil 4 is installed between the extruder head 1 and the capstan 3. The cable conductor W is preheated, and a guide roll 6 is installed at least on the traveling catenary locus of the cable conductor between the extruder-rad and the high-frequency induction heating coil 4, and the inside of the high-frequency induction heating coil is heated. Since the cable conductor running toward the guide roll 6 runs in a straight line, even if the diameter of the high-frequency induction heating coil is made small, there is no risk that the cable conductor will come into contact with the coil while running. By making the diameter of the cable smaller and making the gap between the cable conductor and the cable conductor much smaller than before, it becomes possible to achieve the following, and the heating efficiency can be significantly increased compared to the conventional one.

In addition, the cable conductor that is heated by the high-frequency induction heating coil and sent to the extruder head runs inside an oxidation-preventing cylinder that is fed with active gas, so even if it is heated to a high temperature, the conductor will remain stable. Since the cable conductor can be preheated to a high enough temperature to crosslink the coating without oxidation or discoloration, it is possible to increase the rate of crosslinking.

Furthermore, since the cable conductor W runs inside the oxidation prevention cylinder 7 where an inert gas is fed and exhausted, contaminants such as water vapor adhering to the surface of the cable conductor are removed together with the inert gas. Since the cable conductor, which has been evacuated and has a clean surface, is fed to one end of the extrusion coating machine and extrusion coating is applied thereto, it is possible to prevent the occurrence of voids in the coating due to deposits on the surface of the cable conductor.

[Brief explanation of drawings]

Fig. 1 is a drawing showing one embodiment of the present invention, Fig. 2 is a drawing showing a modification thereof, Figs. 3 and 4 are drawings showing a temperature measuring device, and Fig. 5 is a diagram showing the diameter of a cable conductor. 2 is a drawing showing the heating efficiency according to the ratio of the diameters of the high-frequency induction heating coil. 1; Extrusion coating machine head 2 2 High-frequency induction heating coil 6, guide roll 7 Antioxidant cylinder Patent applicant Furukawa Electric Co., Ltd. Representative Patent attorney Oka 1) Kikuji Kikuji (and 1 other person)

Claims (1)

[Claims] In an inclined continuous crosslinking device that preheats a cable conductor fed to the extruder head by a high frequency induction heating coil provided upstream of the extruder head, at least the cable conductor between the extruder head and the high frequency induction heating coil. A guide roll is installed on the running catenary trajectory, and a cable conductor that passes through the high-frequency induction heating coil and runs in the direction of the guide roll is run in a straight line, and is heated by the high-frequency induction heating coil and extruded. A cable conductor feeding method for an inclined continuous cross-linking device, characterized in that the cable conductor fed to the machine is run inside an oxidation prevention cylinder to which an inert gas is fed.