JPS588083B2 - Kinzokusis Osonaeta Uniyuukable Oseizosuru Hohou Oyobi Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for sheathing a core impregnated with fluid oil with a metal sheath, and more particularly to a method and apparatus for forming seamless long submarine cables.

As used herein, the term core shall generally mean a conductor insulated with cellulose paper and preferably (but not necessarily) wrapped in metal lined fabric.

In a known method of manufacturing sheathed oil-filled cables, the cores, collected in the form of a coil in a dish (toroidal vessel) located in a sealed autoclave, are heated under high vacuum conditions. dried and then impregnated.

After impregnation, the core in the dish is completely immersed in a bath of degassed oil.

That is, it is submerged approximately 10 cm below the surface of the oil in the tank.

At this point, the autoclave is opened and the tray is removed and transported with the core inside to the upstream side of a press (the term press refers to a metal sheath for extruding metal sheaths such as lead or aluminum). equipment).

From this point the core to be sheathed is passed through the extruder via a siphon connected to one end of the extruder by a gas-tight connecting tube reaching the male of the extruder.

In this device, a liquid column pressure gauge, in which a vacuum has been previously created, is located at the highest point of the siphon, and this liquid column pressure gauge is connected to the siphon by a check valve.

At the top of the liquid column pressure gauge, a stage in the sheathing process (herein referred to as the first stage or processing stage) and a system for transferring the core from the impregnating oil tank to the sheath extrusion location are placed under high vacuum. A high vacuum condition is provided in which the process (consisting of processing under conditions) can be carried out.

As used herein, the term "transfer system" means at least a siphon connected to a liquid column pressure gauge, an extruder, and an extruded cable section with a sealed end (as described below). shall be.

Vacuum processing actually consists of a series of operations to eliminate any trace of air or moisture from the transfer system.

Furthermore, in these processes, when the extruder is started and begins operation, a plug hooked to the pulling rope at one end and connected to the cable tip at the other end reaches the sheath to be extruded and It is threaded through the siphon until it engages the sheath.

At this moment, the check valve connecting the liquid column pressure gauge to the siphon opens.

The turbulent mass of oil and foam rises again in the siphon and reaches the liquid column pressure gauge, where it is injected.

As a result, the oil coming from the oil tank flows towards and fills the airtight tube connected to the extruder and the extruded metal tube.

After a few minutes, the bubbles are evacuated, but unfortunately not all of the air and moisture that was present in the transfer system is eliminated.

On the other hand, the risk of air and moisture absorption by the outer paper wrapped around the core is reduced during the second stage, referred to herein as the transfer stage (i.e. when the end of the core is introduced into the sheath). It is still present during the period (from time to time, including during the entire sheathing period, up to and including completion of the sheathing of the core itself).

Some attempts have been made to eliminate this risk by supplying degassed pressurized oil to the "lower" end of the skein.

The term "lower" means the end of the tension rope opposite the hooked end.

However, due to the water permeability of the paper, the oil passes through this paper, and after passing through the 50 m core length of the paper, the oil already leaves the duct and flows out through the tank.

Similar unsatisfactory results occur when using a weak stream of degassed oil from the draw end feed.

This weak current comes into play when the drawing end reaches the winding drum.

Furthermore, in currently used systems, the exit of the extruded sheath from the extruder and the storage of the cable downstream thereof are partially at a level above the oil level in the tank containing the core to be sheathed. This results in severe damage to the cable as it becomes compressed at just the final stage of the sheathing process, referred to herein as the third or completion stage.

In addition to sheathing the core, this completion step also includes storage of the finished core.

The aim of the present invention is to eliminate the above-mentioned disadvantages by providing a method and a device that make it possible to manufacture cables without gas traces in the cables even when the cables are long.

In particular, it is an object of the present invention to provide a first stage for handling the core transfer system from the impregnation bath to an extruded sheath with sealed ends under high vacuum conditions and a second stage for transporting the core. The present invention provides a method for applying a metal sheath to an impregnated core, the method comprising the steps of: the system is then fed with degassed oil under pressure, and in a second stage of transferring said core, said transfer system after filling the transfer system with degassed oil under pressure. is communicated with the impregnating tank on the oil surface of the fluid oil in the impregnating tank,
The supply of degassed fluid oil under pressure is continued until a strong permanent flow from the transfer system toward the impregnation tank is obtained by the fluid oil, and then the core is moved opposite to the direction of movement of the permanent flow. In the third stage, the ends of the core are mechanically connected to a metal sheath and covered with a metal sheath and fitted with suitable means. The core stored above is held at a pressure greater than the external pressure acting on the oil level in the impregnation tank.

Another object of the invention is to provide an apparatus for carrying out the above method, in which the transfer system comprises a siphon, which siphon carries at its highest point a liquid column pressure gauge. However, the liquid column pressure gauge can be connected to a vacuum pump and one end of the siphon is connected to an airtight tube that reaches the male die of the extruder.

A feature of this device is that the siphon consists of a stainless steel tube equipped with a nozzle for supplying degassed oil under pressure, the stainless steel tube having an opening at its free end; is tightly closed by the closure means before creating a high vacuum during the first stage.

The core 10 of the basin forming the electrical cable impregnated with fluid oil is first placed in a dish 11 (for example Italian Patent No. 7218
04 and 801,543);
The dish 11 is placed in a closed autoclave (not shown) in which the core is dried under high vacuum conditions and the core is then impregnated.

After impregnation, the core 10 in the pan 11 is immersed in a bath of degassed fluid oil in which the core is at least about 10 cm
m below the water surface.

That is, the core is submerged within the oil bath such that the uppermost portion of the core is at least about 10 cm below the water surface 12 of the oil bath.

Then, the dish 11, with the core disposed inside it, is transported by suitable means, such as a crane (not shown), onto the rotating table 13 located upstream of the sheath device 14.

The core 10 has a sealed "lower" end and a ribbed other end (pulled end).

The sheathing device 14 consists of a siphon 15, a vacuum-tight connecting tube 16, a metal sheath (for example made of lead or aluminium) sump extruder 17 and at least one collecting drum 18.

The free end 19 of the siphon 15 extends into the dish 11 and is provided with special closing means, such as a plug, which makes it possible to tightly close the opening of this free end.

The siphon 15 preferably consists of a stainless steel tube with a mirrored inner surface.

The cross section of the siphon has an inner diameter that is larger than the outer diameter of the core.

The cross section of the siphon 15 may have an inner diameter that is, for example, twice as large as the outer diameter of the core.

The tube constituting the siphon 15 is provided with one or more elastic joints 20.

In a preferred embodiment, the stainless steel tube that makes up the siphon 15 is made of several tubular pieces joined together by a corrugated tubular body (resilient joint) that gives the siphon some flexibility. Made.

The siphon 15 is also supported at several points by suitable supports (not shown), for example in the form of a grid, so that they can be displaced horizontally and vertically.

The other end 21 of the siphon 15 is connected to the free end of a gas-tight connecting tube 16 of the conventional type which is provided in the sump of the extruder 17 and extends to the male of the extruder.

It should be noted that the extruder outlet is spaced above the floor below the level of the oil in the oil tank.

The extruder 17 is adapted to extrude lead or aluminum depending on the material to which the cable is to be made.

Downstream of the extruder 17 is a suitable drum 18 for collecting the metal sheathed core 27.

The uppermost point of this drum 18, located downstream of the extruder 17, is below the water level 12 of the fluid oil in the pan 11.

If necessary, between the extruder 17 and the drum 18 a corrugator (for example, a sheath (if made of Anovenium))
Other devices such as corrugators, winding regulators, and cooling tanks may also be installed.

A liquid column pressure gauge 22 is provided at the highest point of the siphon 15.

This liquid column pressure gauge is equipped with a transparent tube 23 at its upper end, which leads to a tank 24 connected to a vacuum pump 25.

A nozzle 26 is provided at the lowest part of the siphon 15 on the upstream side of the extruder and in the vicinity thereof.

In particular, at a short distance from the extruder's airtight connecting tube 16, the nozzle connects the siphon to a source of degassed oil coming from a sump degasser (not shown) of the apparatus. playing a role.

After being dried in the autoclave, the dish 11 containing the core 10 is removed from the autoclave, and the impregnated core is placed on the rotating table 13.
Although the oil covering the cable tends to absorb air, the core is preferably submerged at least 10 cm below the oil surface so that it is temporarily protected.

The first stage of the sheathing method, described above as the Transfer System Processing Stage, now begins.

The free end 19 of the siphon 15 is closed with a closing means, for example a plug, and a vacuum is created in the transfer system by means of a vacuum pump 25.

The term "transport system" as used herein means:
In particular, it refers to the parts consisting of the sealed extrusion sheath part 28, the extruder 17, the airtight connecting tube (see for example Italian Patent No. 570,780), the siphon 15 and the liquid column pressure gauge 23. .

When the vacuum is at a suitable value, ie about 0.01 mm/Hg, degassed oil coming from the degasser (not shown in Figure 1) of the device is sent to the siphon via nozzle 26. .

When the oil reaches a certain level in the liquid column pressure gauge 22 as seen through the transparent tube 23, the free end 1 of the siphon 15 is removed without interrupting the supply of degassed oil via the nozzle 26.
The plug closing 9 is removed, the free end remaining immersed in the oil in pan 11.

Therefore, the degassed oil passes through the siphon 15 to the dish 11.
will be transferred to.

Dish 11 is provided with one or more overflows (not shown) located diametrically opposite free end 19 .

These overflows! Substantially the same amount of oil that was supplied to the system is returned to the degasser.

In this way, a strong permanent closed-circuit circulation flow is created (arrows indicate the direction of circulation and the same elements as in FIG. (See Figure 2, where the container is indicated at 29).

This circulating flow completely refreshes the oil in the pan 11 in about 30 minutes and maintains the degree of degassing of the oil within an acceptable value.

At this moment it is possible to begin the step referred to below as the "transfer phase".

During this transfer phase, the operator grasps the ribbed end of the core 10 and pushes it into the siphon 15 through the opening in the free end 19, which is also in the oil, while keeping it in the oil.

This auxiliary operation of end insertion is facilitated by forcing the end of the core into the siphon 15 by manual rotation of the dish 11.

The turntable 13 is then rotated and the core 10 is pushed in by the rotation of the dish 11 and by the ribbed shape of the end of the core itself and by the presence of excess fluid oil in the siphon 15 and by the siphon. The mirror-like inner surface assists in the pushing so that it easily enters the interior of the siphon and reaches the rigid member of the tube 16.

That is, the core enters the extruder. As shown in the block diagram of FIG. 2, the permanently circulating flow of fluid oil created as described above encounters the core 10 from a direction opposite to the direction of movement of the core (i.e. from the opposite direction). , and the outer layer of the insulator is vigorously cleaned to remove any gas traces formed on this outer layer.
aces).

These gas traces are extremely small in each case.

This is because the core 10 in the dish 11 is protected by a layer of fluid oil which is never in contact with air and which is furthermore rapidly resuscitated by the oil flowing from the free end 19 of the siphon 15.

When the end of the core 10 reaches the extruder 17, the extruder drags the core and covers it with a metal sheath.

It is now possible to begin what is referred to herein as the third or completion stage.

After subjecting the metal sheath-coated core to the necessary conventional processes (eg, cooling and corrugation in the case of aluminum), the metal sheath is mechanically coupled to the ends of the core 10.

That is, the sheath engages with the O-ring at the end of the core 10 (as described, for example, in Japanese Patent Publications No. 41-15141 and Japanese Patent Publication No. 46-16626), and the excess portion is removed from the sheath. 28 is removed so as to open the oil duct of the cable connected to the degasser 29 when the core or formed cable begins to wind on the drum 18.

This oil (see Figure 3) passes through the central duct where the cable is sheathed and then exits through the insulating paper into the siphon, increasing the counterflow of oil in the sump to clean the core 10 in the siphon 15. let

The device of FIG. 1 comprises a core 1 comprising at least a conductor and an insulating paper, preferably also comprising an outer winding of metal-lined fabric.
It is shown that the impregnation with fluid oil for 0 is carried out in a toroidal vessel which is immersed in a conventional impregnation tank or autoclave and then transferred to a rotating table after impregnation.

However, it is clear that the apparatus and the method can also be carried out in which the treatment of the core and the subsequent impregnation are carried out on a rotating table consisting of a toroidal vessel acting as an impregnation tank.

Dish-shaped impregnation systems are further preferred.

This is because this dish-shaped system offers cost-saving advantages over tank-shaped impregnation systems.

In fact, the dish-shaped impregnation system allows the tank to remain clean, which makes it possible to keep the tank clean for another impregnation cycle or for other impregnation systems, e.g. with viscous compounds other than fluid oil. This allows the tank to be used immediately.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of an apparatus for sheathing or forming a cable impregnated with fluid oil according to the method of the present invention; FIG. 2 is a diagram showing the circulation of fluid oil within the device before collecting the already sheathed cores onto the drum; FIG. 3 is a diagram showing the circulation of fluid oil within the device after collecting the already sheathed cores on the drum. 10: Core, 11: Dish, 13: Turntable, 15: Siphon, 16: Airtight connection tube, 17: Extruder, 18: Collection drum, 19: Free end of siphon, 22: Liquid column pressure gauge, 25: Vacuum Pump, 26: Nozzle, 29: Degasser.

Claims (1)

[Claims] 1. A method for sheathing a core 10 of an electrical cable having a conductor surrounded by an insulator, having at least one oil passage therein, and impregnated with fluid oil, the method comprising: Starting from the withdrawn end of the core, the sheath 2 is applied to the core while the core is moving from an atmospheric pressure container 11 immersing the core in a water-free liquid.
8, the core is adapted to be transferred to an extruder 17 for applying a sheath to the core, the drawing end of said core being connected to a source of Kada degassed oil at a collection point of the sheathed core, and an extruder 17 for applying a sheath to the core. A housing 15,1 whose core portion between the point of the container 17 and the container is airtight except for one end 19 of the container and the other end of the extruder.
6, 17, the housing 15, 16, 17 is sealed at the end, the gas present in the housing is vented from the housing, and the housing is pressurized. filled with degassed oil, said one end 19 of said housing being open and positioned within said container to discharge oil from said housing into said container 11 through said housing. Oil is supplied from a degasser to the housing at a point 26 remote from the container so as to flow the oil towards the housing, and the withdrawn end of the core 10 is inserted into the housing sog from the one end 19 of the housing. , through the housing to the other end, and while applying the sheath 28 to the core 10, the core is moved through the housing in a direction away from the container 11 to the point 26 of the housing and to the core 10. The supply of oil from the degasser to the part 1 of the housing passes through the point 26.
5, through said vessel 11 and back to said degasser to cause a flow of oil along the moving core 10 in a direction opposite to the direction of movement of said core. and the connection of the draw end of the core to the source of pressurized degassed oil at the collection point of the sheathed core is such that the connection of the draw end of the core to the source of pressurized degassed oil at the collection point of the sheathed core , adapted to maintain a flow of oil in a direction opposite to the direction of movement of the core as a permanent closed circuit flow through the housing and the vessel back to the degasser. Said method. 2. A transfer system for transferring the core from the impregnation tank containing the unsheathed cable core to the sheath extruder, the transfer system consisting of a siphon, the siphon having a liquid column pressure gauge at its highest point. manufacturing a cable by sheathing an impregnated core such that the liquid column pressure gauge can be connected to a vacuum pump and one end of the siphon is connected to an airtight tube that reaches the male mold of the extruder. In the apparatus, the siphon comprises a stainless steel tube with a nozzle for supplying degassed pressurized oil, the free end of the stainless steel tube being provided with an opening, the opening being Cable manufacturing device, characterized in that it is closed by means of a closing means before creating a high vacuum in the transfer system.