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EP0048426A1 - Manufacturing method for a preform for an electric cable with compressed mineral insulation - Google Patents

Manufacturing method for a preform for an electric cable with compressed mineral insulation Download PDF

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Publication number
EP0048426A1
EP0048426A1 EP81107248A EP81107248A EP0048426A1 EP 0048426 A1 EP0048426 A1 EP 0048426A1 EP 81107248 A EP81107248 A EP 81107248A EP 81107248 A EP81107248 A EP 81107248A EP 0048426 A1 EP0048426 A1 EP 0048426A1
Authority
EP
European Patent Office
Prior art keywords
preform
mineral
organic binder
sheath
internal channel
Prior art date
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.)
Granted
Application number
EP81107248A
Other languages
German (de)
French (fr)
Other versions
EP0048426B1 (en
Inventor
Jean-Claude Bourget
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cables de Lyon SA
Original Assignee
Cables de Lyon SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Cables de Lyon SA filed Critical Cables de Lyon SA
Publication of EP0048426A1 publication Critical patent/EP0048426A1/en
Application granted granted Critical
Publication of EP0048426B1 publication Critical patent/EP0048426B1/en
Expired legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00Ohmic-resistance heating
    • H05B3/40Heating elements having the shape of rods or tubes
    • H05B3/42Heating elements having the shape of rods or tubes non-flexible
    • H05B3/48Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/004Apparatus or processes specially adapted for manufacturing conductors or cables for manufacturing rigid-tube cables
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • YGENERAL 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
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/49Method of mechanical manufacture
    • Y10T29/49002Electrical device making
    • Y10T29/49117Conductor or circuit manufacturing
    • YGENERAL 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
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/53Means to assemble or disassemble
    • Y10T29/53478Means to assemble or disassemble with magazine supply
    • Y10T29/53487Assembling means comprising hand-manipulatable implement
    • Y10T29/53513Means to fasten by deforming

Definitions

  • the present invention relates to a method of manufacturing a preform made of electrical insulating material for an electrically insulated mineral cable.
  • These preforms are cylindrical, and provided with one or more longitudinal channels for the introduction of the conductors.
  • Preforms of this kind have so far been manufactured by tableting under high pressure.
  • the mineral insulating material In the pastillage under high pressure, the mineral insulating material, previously moistened, is introduced into a matrix which is subjected to high pressure. Preforms are obtained comprising conductor passage channels very well centered, but in very short lengths (elements of the order of cm). This discontinuous process makes it possible to obtain productions only from 2 to 16m / hour approximately. These elements are then introduced one after the other into the tube intended to form the sheath, which is a relatively long operation.
  • the other method of filling the tubes consists of introducing the mineral insulating material in powder form into the metal tube arranged vertically and provided with its conductor (s), while compacting it. This process does not ensure good centering of the conductors, and gives a lower compactness than the previous one, especially during the first stretching of cable formation. It only allows for relatively short cable lengths.
  • the object of the present invention is to remedy the drawbacks of one and the other of the known methods, and to allow the production of preforms in a partially continuous manner, with a time of threading in the tubes significantly reduced compared to the method of pastillage under high pressure, with productions up to 250m / hour. It also aims to allow excellent centering of the conductor accommodation channels.
  • the magnesia is purified by elimination of its impurities, in particular by magnetic means.
  • the magnesia is added with an organic glue introduced in 3.
  • the mixture is then introduced into the screw extruder shown diagrammatically in 4, comprising a feed screw 5 and a perpendicular compression 6.
  • the cylinder formed, of a specific mass of approximately 2.4 g / em 3 is cut by a guillotine 7, to the dimension of the cooking supports.
  • the preforms obtained are placed on these supports at 8, pass through an oven 9 where they are heated to 250 ° C.
  • the supports with their preforms are loaded into wagons and introduced into the oven 10 with rotary hearth or continuous passage and gradually increasing in temperature, where the preforms are baked in air at a temperature in the region of 1300 ° C.
  • the preforms are introduced into an oven 11, where they are cooled to 200 ° C.
  • the preforms are then introduced hot 12 into the tubes intended to serve as a sheath, guiding them by pins.
  • the tubes are then sent to the wire drawing for the manufacture of the cables, in the known manner.
  • the cooking temperature must be adapted to the nature of the mineral insulating material. It is possible to use, if appropriate, other mineral insulators than those which have been mentioned above.
  • the invention is particularly applicable to the manufacture of heating elements or thermocouples, as well as all electrical cables intended to be placed in an environment at high temperature.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Press-Shaping Or Shaping Using Conveyers (AREA)
  • Resistance Heating (AREA)
  • Insulated Conductors (AREA)
  • Inorganic Insulating Materials (AREA)
  • Processes Specially Adapted For Manufacturing Cables (AREA)

Abstract

Pour fabriquer une préforme pour câble électrique à isolant minéral comprimé, on mélange (2) l'isolant minéral avec un liant organique, on extrude (4) une structure cylindrique à au moins un canal interne, on coupe (7) le matériau cylindrique extrudé à une longueur déterminée, et on le soumet (10) à un traitement thermique de combustion du liant. On enfile à chaud la préforme ainsi fabriquée dans un tube métallique destiné à servir de gaine et on y introduit le ou les conducteurs dans le ou les canaux internes.To make a preform for an electric cable with compressed mineral insulation, we mix (2) the mineral insulation with an organic binder, we extrude (4) a cylindrical structure with at least one internal channel, we cut (7) the extruded cylindrical material at a determined length, and it is subjected (10) to a thermal treatment for burning the binder. The preform thus manufactured is threaded hot into a metal tube intended to serve as a sheath and the conductor (s) are introduced into the internal channel (s).

Description

La présente invention concerne un procédé de fabrication d'une préforme en matériau isolant électrique pour câble électrique à isolant minéral. Ces préformes sont cylindriques, et munies d'un ou plusieurs canaux longitudinaux pour l'introduction des conducteurs.The present invention relates to a method of manufacturing a preform made of electrical insulating material for an electrically insulated mineral cable. These preforms are cylindrical, and provided with one or more longitudinal channels for the introduction of the conductors.

On a jusqu'ici fabriqué des préformes de ce genre par pastillage sous forte pression.Preforms of this kind have so far been manufactured by tableting under high pressure.

Dans le pastillage sous forte pression, on introduit le matériau minéral isolant, préalablement humidifié, dans une matrice que l'on soumet à une forte pression. On obtient des préformes comportant des canaux de passage des conducteurs très bien centrés, mais en très courtes longueurs (éléments de l'ordre du cm). Ce procédé discontinu ne permet d'obtenir des productions que de 2 à 16m/heure environ. Ces éléments sont ensuite introduits l'un après l'autre dans le tube destiné à former la gaine, ce qui est une opération relativement longue.In the pastillage under high pressure, the mineral insulating material, previously moistened, is introduced into a matrix which is subjected to high pressure. Preforms are obtained comprising conductor passage channels very well centered, but in very short lengths (elements of the order of cm). This discontinuous process makes it possible to obtain productions only from 2 to 16m / hour approximately. These elements are then introduced one after the other into the tube intended to form the sheath, which is a relatively long operation.

L'autre procédé de remplissage des tubes consiste à introduire le matériau minéral isolant en poudre dans le tube métallique disposé verticalement, et muni de son ou de ses conducteurs, tout en le tassant. Ce procédé n'assure pas un bon centrage des conducteurs, et donne une compacité plus faible que le précédent, surtout lors des premiers étirages de formation du câble. Il ne permet de fabriquer que des longueurs de câble relativement courtes.The other method of filling the tubes consists of introducing the mineral insulating material in powder form into the metal tube arranged vertically and provided with its conductor (s), while compacting it. This process does not ensure good centering of the conductors, and gives a lower compactness than the previous one, especially during the first stretching of cable formation. It only allows for relatively short cable lengths.

La présente invention a pour but de remédier aux inconvénients de l'un et l'autre des procédés connus, et de permettre la fabrication de préformes de façon partiellement continue, avec une durée d'enfilage dans les tubes notablement réduite par rapport au procédé de pastillage sous forte pression, avec des productions pouvant atteindre 250m/heure. Elle a également pour but de permettre un excellent centrage des canaux de logement des conducteurs.The object of the present invention is to remedy the drawbacks of one and the other of the known methods, and to allow the production of preforms in a partially continuous manner, with a time of threading in the tubes significantly reduced compared to the method of pastillage under high pressure, with productions up to 250m / hour. It also aims to allow excellent centering of the conductor accommodation channels.

Le procédé de l'invention est caractérisé en ce que :

  • a) l'on mélange le matériau minéral isolant avec un liant organique
  • b) on extrude une structure cylindrique munie d'au moins un canal interne,
  • c) on coupe le matériau cylindrique extrudé à une longueur déterminée,
  • d) on le soumet à un traitement thermique de combustion du liant organique,
  • e) on l'enfile à chaud dans le tube métallique destiné à servir de gaine, et on y introduit le ou les conducteurs dans le ou les canaux internes.
The process of the invention is characterized in that:
  • a) the mineral insulating material is mixed with an organic binder
  • b) a cylindrical structure provided with at least one internal channel is extruded,
  • c) the extruded cylindrical material is cut to a determined length,
  • d ) it is subjected to a thermal treatment for combustion of the organic binder,
  • e ) it is threaded hot into the metal tube intended to serve as a sheath, and the conductor (s) are introduced into the internal channel (s).

Il répond en outre de préférence à au moins l'une des caractéristiques suivantes :

  • - Le matériau minéral isolant électrique est de la magnésie, de l'alumine, de la strontiane, de la zircone, de la glucine ou du nitrure de bore.
  • - L'on ajoute au matériau minéral isolant électrique une quantité de liant organique permettant d'obtenir un mélange de la consistance du mastic sec.
  • - L'on effectue la cuisson dans un four à montée progressive en température.
  • - Après cuisson de la préforme, on la refroidit dans une étuve à 200°C environ, puis l'introduit à cette température dans le tube métallique destiné à lui servir de gaine.
It also preferably meets at least one of the following characteristics:
  • - The electrical insulating mineral material is magnesia, alumina, strontiane, zirconia, glucine or boron nitride.
  • - Add a quantity of organic binder to the electrical insulating mineral material to obtain a mixture of the consistency of dry putty.
  • - Cooking is carried out in an oven with gradual rise in temperature.
  • - After cooking the preform, it is cooled in an oven to around 200 ° C, then introduced at this temperature into the metal tube intended to serve as a sheath.

Il est décrit ci-après, à titre d'exemple et en référence à la figure unique du dessin, un procédé de fabrication d'une préforme en magnésie selon l'invention.It is described below, by way of example and with reference to the single figure of the drawing, a method of manufacturing a preform in magnesia according to the invention.

Dans l'étape désignée par le carré 1 de la figure, la magnésie est purifiée par élimination de ses impuretés, notamment par voie magnétique. La magnésie est additionnée dans l'opération représentée par le carré 2, d'une colle organique introduite en 3. Le mélange est alors introduit dans l'extrudeuse à vis représentée schématiquement en 4, comportant une vis d'alimentation 5 et une vis de compression perpendiculaire 6. A la sortie de l'extrudeuse, le cylindre formé, d'une masse spécifique d'environ 2,4g/em3, est coupé par une guillotine 7, à la dimension des supports de cuisson. Les préformes obtenues sont mises sur ces supports en 8, passent dans une étuve 9 où elles sont chauffées vers 250°C. Les supports avec leurs préformes sont chargés dans des wagonnets et introduits dans le four 10 à sole tournante ou à passage continu et à montée progressive en température, où les préformes sont cuites à l'air à une température voisine de 1300°C. A la sortie du four, les préformes sont introduites dans une étuve 11, où elles sont refroidies à 200°C. Les préformes sont alors introduites en 12 à chaud dans les tubes destinés à leur servir de gaine, en les guidant par des broches. Les tubes sont alors envoyés au tréfilage pour la fabrication des câbles, de la manière connue.In the step designated by the square 1 in the figure, the magnesia is purified by elimination of its impurities, in particular by magnetic means. In the operation represented by the square 2, the magnesia is added with an organic glue introduced in 3. The mixture is then introduced into the screw extruder shown diagrammatically in 4, comprising a feed screw 5 and a perpendicular compression 6. At the exit of the extruder, the cylinder formed, of a specific mass of approximately 2.4 g / em 3 , is cut by a guillotine 7, to the dimension of the cooking supports. The preforms obtained are placed on these supports at 8, pass through an oven 9 where they are heated to 250 ° C. The supports with their preforms are loaded into wagons and introduced into the oven 10 with rotary hearth or continuous passage and gradually increasing in temperature, where the preforms are baked in air at a temperature in the region of 1300 ° C. At the exit of the oven, the preforms are introduced into an oven 11, where they are cooled to 200 ° C. The preforms are then introduced hot 12 into the tubes intended to serve as a sheath, guiding them by pins. The tubes are then sent to the wire drawing for the manufacture of the cables, in the known manner.

Bien que le procédé qui vient d'être décrit en référence à la figure du dessin paraisse la forme de réalisation préférable de l'invention, on comprendra que diverses modifications peuvent bien être apportées sans sortir du cadre de celle-ci, certaines de ses opérations pouvant être remplacées par d'autres qui joueraient le même rôle technique . En particulier la température de cuisson doit être adaptée à la nature du matériau minéral isolant. On peut utiliser le cas échéant d'autres isolants minéraux que ceux qui ont été cités ci-dessus.Although the process which has just been described with reference to the figure of the drawing appears to be the preferable embodiment of the invention, it will be understood that various modifications may well be made without departing from the scope thereof, certain of its operations can be replaced by others who would play the same technical role. In particular, the cooking temperature must be adapted to the nature of the mineral insulating material. It is possible to use, if appropriate, other mineral insulators than those which have been mentioned above.

L'invention s'applique particulièrement à la fabrication d'éléments chauffants ou de thermocouples, ainsi que de tous câbles électriques destinés à être placés dans une ambiance à température élevée.The invention is particularly applicable to the manufacture of heating elements or thermocouples, as well as all electrical cables intended to be placed in an environment at high temperature.

Claims (4)

1/ Procédé de fabrication d'une préforme en matériau minéral isolant électrique pour câble électrique à isolant minéral comprimé, carac- térisé en ce qué, afin d'effectuer la fabrication de façon partiellement continue et avec des productions horaires élevées, a) l'on mélange le matériau minéral isolant avec un liant organique (2), b) on extrude (4) une structure cylindrique munie d'au moins un canal interne, c) on coupe (9) le matériau cylindrique extrudé à une longueur déterminée, d) on le soumet (11) à un traitement thermique de combustion du liant organique, e) on l'enfile à chaud (13) dans le tube métallique destiné à servir de gaine, et on y introduit le ou les conducteurs dans le ou les canaux internes. 1 / A method of manufacturing a preform of an electrically insulating inorganic material for electrical cable insulation mineral tablet, charac- t érisé in that, in order to perform the manufacture of partially continuously and with high hourly production, a) the mineral insulating material is mixed with an organic binder (2), b) extruding (4) a cylindrical structure provided with at least one internal channel, c) the extruded cylindrical material is cut (9) to a determined length, d) subjecting it (11) to a thermal treatment for combustion of the organic binder, e) it is threaded hot (13) into the metal tube intended to serve as a sheath, and the conductor (s) are introduced into the internal channel (s). 2/ Procédé selon la revendication 1, caractérisé en ce que le matériau minéral isolant électrique est de la magnésie, de l'alumine, de la strontiane, de la zircone, de la glucine ou du nitrure de bore. 3/ Procédé selon les revendications 1 ou 2, caractérisé en ce que l'on ajoute au matériau minéral isolant électrique une quantité de liant organique permettant d'obtenir un mélange de la consistance du mastic sec.2 / A method according to claim 1, characterized in that the electrically insulating mineral material is magnesia, alumina, strontiane, zirconia, glucine or boron nitride. 3 / A method according to claims 1 or 2, characterized in that one adds to the electrical insulating mineral material an amount of organic binder to obtain a mixture of the consistency of dry mastic. 4/ Procédé selon l'une des revendications 1 à 3, caractérisé en ce que l'on effectue la cuisson dans un four à montée progressive en température.4 / Method according to one of claims 1 to 3, characterized in that the cooking is carried out in an oven with gradual rise in temperature. 5/ Procédé selon l'une des revendications 1 à 4, caractérisé en ce qu'après cuisson de la préforme, on la refroidit dans une étuve à 200°C environ, puis l'introduit à cette température dans le tube métallique destiné à lui servir de gaine.5 / Method according to one of claims 1 to 4, characterized in that after cooking the preform, it is cooled in an oven to about 200 ° C, then introduced at this temperature in the metal tube intended for it serve as a sheath.
EP81107248A 1980-09-23 1981-09-15 Manufacturing method for a preform for an electric cable with compressed mineral insulation Expired EP0048426B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8020393 1980-09-23
FR8020393A FR2490866A1 (en) 1980-09-23 1980-09-23 METHOD FOR MANUFACTURING A PREFORM FOR ELECTRICAL CABLE WITH COMPRESSED MINERAL INSULATION

Publications (2)

Publication Number Publication Date
EP0048426A1 true EP0048426A1 (en) 1982-03-31
EP0048426B1 EP0048426B1 (en) 1985-01-09

Family

ID=9246205

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81107248A Expired EP0048426B1 (en) 1980-09-23 1981-09-15 Manufacturing method for a preform for an electric cable with compressed mineral insulation

Country Status (7)

Country Link
US (1) US4420881A (en)
EP (1) EP0048426B1 (en)
JP (1) JPS5787015A (en)
AU (1) AU539221B2 (en)
CA (1) CA1155279A (en)
DE (1) DE3168156D1 (en)
FR (1) FR2490866A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8527661D0 (en) * 1985-11-08 1985-12-11 Ici Plc Catalyst supports & precursors
US4758398A (en) * 1986-10-07 1988-07-19 The Dexter Corporation Method of manufacture preforms
AU626683B2 (en) * 1989-05-17 1992-08-06 Metal Manufactures Limited Manufacture of mineral insulated metal sheathed cables
US6119922A (en) * 1998-11-17 2000-09-19 Hoskins Manufacturing Company Method for making mineral insulated cable

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB445070A (en) * 1934-05-29 1936-04-02 Le Conducteur Electr Blinde In Electric cables or other insulated electric conductors and the manufacture thereof
FR843366A (en) * 1938-03-07 1939-06-30 Electro Cable Soc Mineral insulated electric wires and cables and their manufacturing processes
US2219523A (en) * 1937-07-17 1940-10-29 Edwin L Wiegand Electric resistance heating element and method of making the same
DE733886C (en) * 1935-10-25 1943-04-05 Sueddeutsche Kabelwerke Zweign Process for the manufacture of refractory electrical cables
CH329528A (en) * 1954-08-27 1958-04-30 Kraffe De Laubarede Leonce Mar Process for the production of heat and electric insulating bodies
US2948647A (en) * 1954-03-12 1960-08-09 British Insulated Callenders Manufacture of insulated electric conductors

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US1523434A (en) * 1920-10-25 1925-01-20 Gutler Hammer Mfg Co Electric heater
US2243881A (en) * 1938-01-18 1941-06-03 Titeflex Metal Hose Co Method for making radio shielded conductors
US2495867A (en) * 1948-01-14 1950-01-31 Petcar Res Corp Method of manufacturing fire detector and like elements
US3017688A (en) * 1957-02-28 1962-01-23 Gen Motors Corp Method and apparatus of making electrical heating elements
US3105287A (en) * 1957-05-08 1963-10-01 Rea Magnet Wire Company Inc Insulated wire particularly for coils and the manufacture thereof
US3121038A (en) * 1960-06-01 1964-02-11 Gen Electric Method of providing a high resistance insulation coating for a conductor in a sheath
GB1109402A (en) * 1966-03-31 1968-04-10 Decca Ltd Improvements in or relating to position indicators for use in mobile craft
US4033028A (en) * 1974-06-21 1977-07-05 Pyrotenax Of Canada Limited Method of making heating cables
DE2514578B2 (en) * 1975-04-03 1978-09-07 Fa. Fritz Eichenauer, 6744 Kandel Refractory, granular investment material for electric heating coils
JPS6018093B2 (en) * 1976-10-20 1985-05-08 三菱電線工業株式会社 Manufacturing method of inorganic insulated wire
US4106186A (en) * 1976-11-24 1978-08-15 The United States Of America As Represented By The United States Department Of Energy Boron nitride insulating material
JPS5814007B2 (en) * 1978-01-18 1983-03-17 日立電線株式会社 Manufacturing method of inorganic insulated wire

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB445070A (en) * 1934-05-29 1936-04-02 Le Conducteur Electr Blinde In Electric cables or other insulated electric conductors and the manufacture thereof
DE733886C (en) * 1935-10-25 1943-04-05 Sueddeutsche Kabelwerke Zweign Process for the manufacture of refractory electrical cables
US2219523A (en) * 1937-07-17 1940-10-29 Edwin L Wiegand Electric resistance heating element and method of making the same
FR843366A (en) * 1938-03-07 1939-06-30 Electro Cable Soc Mineral insulated electric wires and cables and their manufacturing processes
US2948647A (en) * 1954-03-12 1960-08-09 British Insulated Callenders Manufacture of insulated electric conductors
CH329528A (en) * 1954-08-27 1958-04-30 Kraffe De Laubarede Leonce Mar Process for the production of heat and electric insulating bodies

Also Published As

Publication number Publication date
AU539221B2 (en) 1984-09-13
EP0048426B1 (en) 1985-01-09
US4420881A (en) 1983-12-20
FR2490866A1 (en) 1982-03-26
JPS5787015A (en) 1982-05-31
DE3168156D1 (en) 1985-02-21
FR2490866B1 (en) 1983-08-12
CA1155279A (en) 1983-10-18
AU7553181A (en) 1982-04-01

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