US3918281A - Method for sheathing a cable core with the core surrounded by impregnating fluid during sheathing - Google Patents

Method for sheathing a cable core with the core surrounded by impregnating fluid during sheathing Download PDF

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Publication number
US3918281A
US3918281A US517789A US51778974A US3918281A US 3918281 A US3918281 A US 3918281A US 517789 A US517789 A US 517789A US 51778974 A US51778974 A US 51778974A US 3918281 A US3918281 A US 3918281A
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United States
Prior art keywords
core
oil
housing
container
extruder
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US517789A
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English (en)
Inventor
Paolo Gazzana Priaroggia
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Pirelli and C SpA
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Pirelli SpA
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Priority to US05/578,877 priority Critical patent/US3986377A/en
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Publication of US3918281A publication Critical patent/US3918281A/en
Assigned to SOCIETA' PIRELLI S.P.A., A COMPANY OF ITALY reassignment SOCIETA' PIRELLI S.P.A., A COMPANY OF ITALY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: INDUSTRIE PIRELLI S.P.A.
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/22—Sheathing; Armouring; Screening; Applying other protective layers
    • H01B13/24—Sheathing; Armouring; Screening; Applying other protective layers by extrusion
    • H01B13/245—Sheathing; Armouring; Screening; Applying other protective layers by extrusion of metal layers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/53—Means to assemble or disassemble
    • Y10T29/53096—Means to assemble or disassemble including means to provide a controlled environment
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/53—Means to assemble or disassemble
    • Y10T29/53126—Means to place sheath on running-length core

Definitions

  • the metal sheathed core is transferred to 29/202 5 156248 1 a drum and during such transfer the core is subjected to oil under pressure.
  • the apparatus Prior to inserting the core in the [56] References Cited siphon tube, the latter is evacuated and filled with degassed oil.
  • the apparatus comprises a stainless steel UNITED STATES PATENTS siphon tube with one end in the container and the 2.115.574 /1 38 Gas other end connected to the extruder.
  • the siphon tube grlfiroggla el has a higher intermediate portion to which a piezometric column and a pump are connected and has a 5:22:32: et coupling adjacent the extruder for supplying degassed 3,444,016 5/1969 Baskwell 156/48 011 to the slpho tube' 3,514,349 5/1970 Shiroya et a1.
  • the present invention relates to a process and apparatus for covering a core impregnated with fluid oil with a metal sheath which are particularly useful for manufacturing submarine cables of long length and without joints.
  • core means a conductor, generally insulated with cellulose paper and preferably, but not necessarily, wrapped with metallized cloth.
  • the core is first collected in coils in a pan in the shape of a toroidal container situated in a closed autoclave and is dried under high vacuum and then impregnated. After impregnation, the core is immersed in the pan or tank in a degassed oil bath and under a head, namely, is submersed for about ten centimeters under the surface of the bath.
  • the autoclave is opened, the pan is removed and is transferred, together with the core contained therein, to a position upstream of an extrusion press, i,e., apparatus able to extrude a metal sheath, for example, oflead or aluminum over the core.
  • the core to be sheathed passes to the extruder through a siphon tube connected at one end to the extruder by means of a vacuum-tight connection tube which extends to the mandrel of the extruder.
  • a piezometric column where vacuum has been previously created, is situated at the highest point of the siphon system, and in general, is connected to it by means of a check valve.
  • the high vacuum is applied which permits the carrying out of that stage in the sheathing process which in the present description is defined as first stage or treatment stage.
  • Such stage comprises subjecting the system for transferring the core from the immersion bath to the sheath extrusion position to a high vacuum.
  • the expression transferring system means herein at least the siphon tube connected to the piezometric column, at least a portion of the extruder and the length of cable having an extruded sheath thereon and having a sealed end, which will be described hereinafter.
  • the vacuum treatment consists essentially of a series of operations intended to eliminate almost all traces of air or moisture from the transferring system.
  • the extruded sheath at the outlet of the extruder and the stored cable downstream of the extruder always is partially or totally situated at a level higher than the oil surface level in the tank containing the core to be sheathed, and seriousdamage to the cable can result by undergoing a lowering of pressure in the last stage of the sheathing process.
  • the last stage is herein defined as a third stage, or completion stage, which is that stage providing, in addition to the sheathing of the core, the storage of the finished cable.
  • the present invention has, as one object, the elimination of the disadvantages described hereinbefore by providing a process, and apparatus for carrying out the process, by means of which it is possible to produce sheathed cables devoid of any trace of gas even in long lengths.
  • the principal object of the present invention is a process for the metal sheathing of an impregnated core, which comprises a first stage in which the core transferring system which extends from the immersion bath to the sheath being extruded and provided with an end seal is subjected to a high vacuum, a second stage in which the core is transferred and a third stage in which the sheathed cable is completed and stored.
  • the preferred embodiment of the invention comprises the following steps:
  • a high vacuum is first produced in the transferring system and subsequently, said system is supplied with degassed fluid oil under pressure;
  • the core is mechanically connected to the metal sheath, and said core, as it is being covered with the metal sheath and stored on an appropriate means, is kept at a pressure higher than the atmospheric pressure acting on the surface level of the oil bath.
  • a further object of the present invention is apparatus for carrying out the process described hereinbefore, in which apparatus said transferring system is a siphon tube which is connected at its highest point to a piezometric tube which can be connected to a vacuum pump and which siphon tube is connected at one end with a vacuum-tight tube reaching the mandrel of the extruder.
  • Said siphon tube preferably is a tube of stainless steel provided with a coupling for feeding thereto the degassed oil under pressure, said tube having the opening at its opposite, free end provided with a closing means which permits closing of such end in a vacuumtight manner before producing the high vacuum during the first stage.
  • FIG. 1 is a diagrammatic, side elevation view of a plant for manufacturing a sheathed cable impregnated with fluid oil according to the process of the invention
  • FIG. 2 is a schematic diagram showing the circulation of the fluid oil in the plant before collecting the cable on a bobbin or reel;
  • FIG. 3 is a schematic diagram showing the circulation of the fluid oil in the plant after collecting the already sheathed core on the bobbin.
  • a core 10, intended to form part of an electric cable impregnated with fluid oil, is at first collected in coils in a pan 11 which may, for example, be a toroidal container of the type described in Italian Pat. No. 721,804
  • the core has previously been situated in a closed autoclave (not shown) where it is dried under high vacuum and then impregnated with oil. After impregnation, the core 10 is immersed in a bath of degassed fluid oil in the pan 11 and is placed under the surface 120 of the oil 12 a distance of at least about 10 centimeters, namely, with the highest point of the core 10 at at least about 10 centimeters below the surface 12a of the oil bath.
  • the pan 11, together with the core 10 arranged inside it, is then transported by an appropriate means, for example, a crane (not shown) to a rotatable platform 13 situated upstream of the sheathing portion 14 of the plant.
  • an appropriate means for example, a crane (not shown) to a rotatable platform 13 situated upstream of the sheathing portion 14 of the plant.
  • the lower, or trailing, end of the core 10 is sealed in any suitable manner and the other, or leading, end of the core 10 has an ogival shape in longitudinal crosssection so as to facilitate its passage into a siphon tube as described hereinafter.
  • the sheathing portion 14 of the plant comprises a siphon tube 15, a vacuum-tight connection tube 16, a conventional extruder 17 for extruding a sheath of metal, e.g., lead or aluminum, over the core 10 and at least a collecting bobbin or drum 18.
  • the free end 19 of the siphon tube 15 is in the oil 12 in the pan l1 and is provided with a closing means 15b, for example, a plug which permits closing of its end in a vacuum-tight manner.
  • the siphon tube 15 is preferably composed of a tube of stainless steel having a specular inner surface, and the tube 16 may be of the type shown and described in US. Pat. No. 2,981,409.
  • the cross-section of the siphon tube 15 has an inner diameter greater than the outer diameter of the core 10 and can have, for example, an inner diameter which is double the outer diameter of the core 10.
  • the siphon tube 15 is provided with one or more elastic joints 20.
  • the steel tube 15 is made from several tubular pieces joined together by flexible, corrugated tubular bodies (elastic joints) which impart to the tube 15 a certain flexibility.
  • the siphon tube 15 is also supported, in one or more zones, by appropriate supports 15a, for example, of the trellis type, which permit horizontal and vertical dis placement of the tube 15.
  • the other end 21 of the siphon tube 15 is connected to the first free end of the vacuum-tight connecting tube 16, of a conventional type, provided at the extruder l7 and reaching the mandrel of the same.
  • the output of the extruder 17 is at a height above the floor 30 which is less than the height of the surface 121: of the oil bath 12 so that it is below the upper level of the oil bath 12.
  • the extruder 17 is suitable for extruding lead or aluminum, depending on whether the cable is to be sheathed with one material or the other.
  • a suitable bobbin or drum 18 for collecting or storing the cable 27 which comprises the core 10 covered with the metal sheath.
  • the drum 18 has its highest point situated at a level below the upper surface level 12a of the fluid oil 12 in the pan 11.
  • a corrugator for the sheath if this is made of aluminum, a winding regulator, a cooling tank, etc., can be provided, if necessary or desired, between the extruder l7 and the drum 18.
  • a piezometric column 22 is connected to the siphon tube 15 at the highest point of the siphon tube 15. Said column 22 is provided at its upper end with a transparent sight tube 23 and a vacuum tank 24 connected to a vacuum pump 25.
  • a coupling 26 is provided at one of the lowest points of the siphon tube 15 upstream of the extruder 17 and in proximity to it.
  • the coupling 26 is at a short distance from the free end of the vacuum-tight connection tube 16 of the extruder l7 and said coupling 26 serves to connect the siphon tube 15 with a supply 31 of degassed oil coming from a degasser 29 for the oil of the plant.
  • the oil 12 covering the core 10 tends to absorb air, but the core 10 is temporarily protected because it is under an oil head of preferably at least 10 centimeters.
  • the first stage of the process that is, the stage of treatment of the transferring system.
  • a short section 28 of the sheath is extruded and sealed at its outward end.
  • the free end 19 of the siphon tube 15 is closed with the closing means 15b, e.g., a plug, and vacuum is created in the transferring system by means of the vacuum pump 25.
  • the expression transferring system means the portion 28 of extruded sheath with its sealed end, the extruder 17, the vacuumtight connecting tube 16, the siphon tube 15 and the piezometric column 22.
  • degassed oil coming from the supply 31 connected to the plant oil degasser 29, is sent to the siphon tube 15 through the coupling 26.
  • Degassed oil is therefore transferred to the pan 11 through the siphon tube 15.
  • the pan 11 is provided with one or more overflow outlets (not shown) situated in a position diametrically opposite to the free end 19. Such outlets send oil back to the degasser practically in the same amount as is supplied to the transferring system.
  • FIG. 2 illustrates diagrammatically the oil flow at this time, and it will be noted that the oil circulates in a closed path.
  • the transferring stage in which the operator takes the ogival, leading end of the core and, while maintaining it under the oil 12, pushes it into the siphon tube through the opening of the free end 19,also under the oil 12.
  • This preliminary operation of insertion of the end is facilitated by pushing it into the siphon tube 15 as the pan 11 and the platform 13 are manually rotated.
  • the platform 13 is placed into automatic, driven rotation, and the core 10, pushed by the rotation of the pan 11 and aided by the ogival shape of its end, by the presence of the extremely fluid oil in the siphon tube 15 and by the specular inner surface of the latter, travels easily into the siphon tube 15 until it reaches the vacuum-tight tube 16 and enters the extruder 17.
  • the continuous stream of the fluid oil provided as shown in the diagram of FIG. 2 meets the core 10 in a sense opposite to the motion of the latter, namely, in counter-current thereto, and exerts a strong washing effect on the outer layers of the insulation thereby removing the gas traces which may exist on the insulation.
  • gas traces in any case, would be very small because the core 10 does not come into contact with air and is protected by a layer of fluid oil 12 which is rapidly renewed by the oil flowing from the free end 19 of the siphon tube 15.
  • the core 10 is pulled along in the extruder as it is covered with the metal sheath.
  • the metal sheath is mechanically connected to the end of the core 10, namely, said sheath engages on the O-rings of said end of the core 10 as described, for example, in US. Pat. No. 3,342,162 and as indicated in US. Pat. No. 3,561,250.
  • the plant of FIG. 1 illustrates the case in which the impregnation with fluid oil of the core 10, comprising at least a conductor and the insulating papers, but preferably also provided with an outer winding of metallized cloth, has taken place in the toroidal container 11 immersed in a normal impregnation tank or autoclave and then, transported on the rotatable platform 13 after impregnation.
  • the same plant and the same process can be applied also when the treatment of the core 10 and its subsequent impregnation take place on the same rotatable platform 13 supporting a toroidal container acting as an impregnation tank.
  • pan type impregnating system is, however, the preferred one, since it affords the advantage of obtaining considerable savings with respect to the tank impregnation system.
  • the former permits the pan 11 to be left clean and can be immediately used for other impregnation cycles or for other impregnation systems, for example, with viscous compounds rather than with fluid oil.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacturing Of Electric Cables (AREA)
  • Insulated Conductors (AREA)
  • Coating Apparatus (AREA)
US517789A 1973-11-21 1974-10-24 Method for sheathing a cable core with the core surrounded by impregnating fluid during sheathing Expired - Lifetime US3918281A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US05/578,877 US3986377A (en) 1973-11-21 1975-05-19 Apparatus for sheathing a cable core with core surrounded by impregnating fluid during sheathing

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT31497/73A IT1001848B (it) 1973-11-21 1973-11-21 Procedimento e impianto per la mes sa in guaina metallica di un anima impregnata in olio fluido

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US05/578,877 Division US3986377A (en) 1973-11-21 1975-05-19 Apparatus for sheathing a cable core with core surrounded by impregnating fluid during sheathing

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US517789A Expired - Lifetime US3918281A (en) 1973-11-21 1974-10-24 Method for sheathing a cable core with the core surrounded by impregnating fluid during sheathing

Country Status (11)

Country Link
US (1) US3918281A (fr)
JP (1) JPS588083B2 (fr)
AR (1) AR209284A1 (fr)
BR (1) BR7409759A (fr)
CA (1) CA1029535A (fr)
ES (1) ES432361A1 (fr)
GB (1) GB1452388A (fr)
IT (1) IT1001848B (fr)
NO (1) NO141912C (fr)
SE (1) SE404273B (fr)
ZA (1) ZA747370B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4265686A (en) * 1979-09-13 1981-05-05 Northern Telecom Limited Power filling of cable core units
GB2165690A (en) * 1984-10-08 1986-04-16 Ass Elect Ind Electrical cables

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2115574A (en) * 1933-09-14 1938-04-26 Siemens Ag Method of eliminating gas pockets in liquid filled cables
US3013912A (en) * 1956-07-14 1961-12-19 Pirelli Oil filled cables
US3032464A (en) * 1956-10-31 1962-05-01 British Insulated Callenders Manufacture of oil-filled cables
US3238757A (en) * 1960-11-03 1966-03-08 Leybold Anlagen Holding A G Method and apparatus for manufacturing oil filled cables
US3409488A (en) * 1961-01-17 1968-11-05 Furukawa Electric Co Ltd Method of manufacturing oil-filled cables
US3444016A (en) * 1962-09-19 1969-05-13 Pirelli General Cable Works Sheathing of electric cables
US3514349A (en) * 1960-10-19 1970-05-26 Sumitomo Electric Industries Method of manufacturing oil filled electric cables and apparatus for manufacturing the same
US3854444A (en) * 1971-06-21 1974-12-17 Western Electric Co Apparatus for manufacturing waterproof cable
US3876464A (en) * 1973-06-29 1975-04-08 Schlumberger Technology Corp Water and gas blocked logging cable

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2115574A (en) * 1933-09-14 1938-04-26 Siemens Ag Method of eliminating gas pockets in liquid filled cables
US3013912A (en) * 1956-07-14 1961-12-19 Pirelli Oil filled cables
US3032464A (en) * 1956-10-31 1962-05-01 British Insulated Callenders Manufacture of oil-filled cables
US3514349A (en) * 1960-10-19 1970-05-26 Sumitomo Electric Industries Method of manufacturing oil filled electric cables and apparatus for manufacturing the same
US3238757A (en) * 1960-11-03 1966-03-08 Leybold Anlagen Holding A G Method and apparatus for manufacturing oil filled cables
US3409488A (en) * 1961-01-17 1968-11-05 Furukawa Electric Co Ltd Method of manufacturing oil-filled cables
US3444016A (en) * 1962-09-19 1969-05-13 Pirelli General Cable Works Sheathing of electric cables
US3854444A (en) * 1971-06-21 1974-12-17 Western Electric Co Apparatus for manufacturing waterproof cable
US3876464A (en) * 1973-06-29 1975-04-08 Schlumberger Technology Corp Water and gas blocked logging cable

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4265686A (en) * 1979-09-13 1981-05-05 Northern Telecom Limited Power filling of cable core units
GB2165690A (en) * 1984-10-08 1986-04-16 Ass Elect Ind Electrical cables

Also Published As

Publication number Publication date
BR7409759A (pt) 1976-05-25
NO141912B (no) 1980-02-18
CA1029535A (fr) 1978-04-18
NO744173L (fr) 1975-06-16
SE7414521L (fr) 1975-05-22
IT1001848B (it) 1976-04-30
GB1452388A (en) 1976-10-13
AR209284A1 (es) 1977-04-15
JPS588083B2 (ja) 1983-02-14
JPS5083783A (fr) 1975-07-07
ZA747370B (en) 1975-12-31
SE404273B (sv) 1978-09-25
NO141912C (no) 1981-06-22
ES432361A1 (es) 1977-04-01
AU7550874A (en) 1976-05-20

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AS Assignment

Owner name: SOCIETA PIRELLI S.P.A., PIAZZALE CADORNA 5, 20123

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:INDUSTRIE PIRELLI S.P.A.;REEL/FRAME:003847/0084

Effective date: 19810101