US3643727A - Process and apparatus for lining conductive tubes with insulating material - Google Patents

Process and apparatus for lining conductive tubes with insulating material Download PDF

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Publication number
US3643727A
US3643727A US18666A US3643727DA US3643727A US 3643727 A US3643727 A US 3643727A US 18666 A US18666 A US 18666A US 3643727D A US3643727D A US 3643727DA US 3643727 A US3643727 A US 3643727A
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US
United States
Prior art keywords
insulating material
tube
set forth
carrier
outlet
Prior art date
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Expired - Lifetime
Application number
US18666A
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English (en)
Inventor
Sergio Longoni
Antonio Portinari
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Pirelli and C SpA
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Pirelli SpA
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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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    • 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
    • H01B13/06—Insulating conductors or cables
    • H01B13/16—Insulating conductors or cables by passing through or dipping in a liquid bath; by spraying
    • H01B13/165—Insulating conductors or cables by passing through or dipping in a liquid bath; by spraying by spraying
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P11/00—Apparatus or processes specially adapted for manufacturing waveguides or resonators, lines, or other devices of the waveguide type
    • H01P11/001—Manufacturing waveguides or transmission lines of the waveguide type
    • H01P11/002—Manufacturing hollow waveguides

Definitions

  • the present invention relates to a process for lining conductive tubes obtained by extrusion with insulating material, as well as to the apparatus for carrying out said process.
  • the process and the apparatus according to the invention are of particular interest in the application of insulation to the inner surface of aluminum waveguides.
  • the present invention aims at eliminating the above-indicated difficulties by providing a process for carrying out an inner lining of the surfaces of conductive tubes, in particular of aluminum waveguides, which provides perfect adhesion of the insulation to the metal and a uniform thickness of the lining without any break in the continuity of the bond therebetween and thereby ensures a good insulating action at all points.
  • a further object of the invention is that of providing, when necessary, an insulating inner lining, the thickness of which may be considerably smaller than one-tenth of a millimeter and hence, considerably thinner than prior art linings.
  • the object of the present invention is to provide a process for the inner lining of conductive tubes obtained by extrusion, such as aluminum waveguides, according to which appropriately selected insulating particles, electrostatically charged and contained in a conveying fluid, are pushed or sprayed uniformly, as the tube comes out of the extruder head, on the inner surface of the tube itself as it advances at high temperature.
  • the particles are sprayed on the mechanically stabilized portion of the tube which is the nearest to the extrusion head, in order that they may adhere perfectly to said surface and may consequently form an insulating layer devoid of breaks in continuity, an appropriate suction device compelling the conveying fluid to flow out of the tube after the deposition of the insulating particles.
  • a further object of the present invention is to provide an apparatus for carrying out the process according to the invention, which comprises an extruder, in which the inner mould of the head is provided with at least means for spraying the conveying fluid containing the insulating particles or powders on the inner surface of the tube obtained by extrusion, and with at least a means able to suck out or remove the conveying fluid after the insulating particles have been deposited on said surface.
  • FIGURE of the attached sheet of drawing illustrates by way of example and in a schematic, cross-sectional, side elevation view a practical embodiment of the apparatus for carrying out the process of the invention.
  • Said figure shows diagrammatically, in longitudinal section, the head of an extruder provided with the means for spraying the insulating particles on the inner surface of the tube to be extruded, and with suction means for removing the conveying fluid from the inside of the extruded tube after the deposition of the particles conveyed by said fluid.
  • the reference numeral 1 indicates the extrusion head which comprises an outer mould 4 and an inner mould 5 which define a duct for conveying the metal 2, in melted state, towards the outlet 3.
  • the inner mould 5 is provided with a lance 6, coaxial with it.
  • An element 7 of insulating material is inserted between the inner mould 5 and the lance 6, and permits the maintaining of the potential of the extruded tube 12 at a value different from the potential of the lance 6.
  • the lance 6 contains the following elements, coaxial with it: a nozzle 8, provided with an adhesive spray duct 13 of annular section, connected to a compressor (not shown) and a duct 10, also of annular section, connected to a vacuum or suction means (not shown) and provided with a suction opening 14.
  • the chamber is coaxial to them and is able to maintain duct 13 at a lower temperature compared to the parts exterior thereto.
  • the cooling chamber 11 may also be divided into two intercommunicating halfchambers by means of a longitudinal partition.
  • Molten metal such as aluminum, contained in the extruders head is forced through the duct defined by the outer mould 4 and by the inner mould 5, and out ofthe outlet 3, where a tube 12, for instance a waveguide, begins to be formed.
  • the lance 6 is disposed in such a way that the nozzle 8 opens in proximity of the zone of the tube extrusion and in a position at which the tube is still hot, but its dimensions are stabilized.
  • particles of insulating material are sprayed in the form of a mist on the inner surface of the tube 12 by the nozzle 8 and a potential difference is maintained between the tube 12 and the lance 6 in any manner conventional in electrostatic spray coating, such as by connecting a direct current source between the tube 12 and the lance 6, so as to aid in causing such particles of insulating material flowing out of the duct 13 along the paths 9 to become deposited on the inner surface of the tube 12.
  • the particles adhere to the inner surface and, depending on the material employed, may melt thereon, to form a uniform insulating layer 15 which is continuous and may be as thin as 0.1 mm. or less. It will be apparent that the thickness of the layer depends upon the material sprayed, the rate at which it is sprayed and the speed at which the tube 12 is formed and is drawn away from the extruding head.
  • the material sprayed may be of any of many different insulating materials known in the art and may, for example, be polyethylene or polypropylene in a gaseous or liquid solvent or carrierv therefor.
  • One particularly suitable material is polyethylene having a density of about 091 and an average molecular weight of 1,500.
  • Suitable gaseous carriers or solvents are nitrogen or dichlorodifluoromethane and suitable liquid is tetrachloroethylene.
  • a mixture of 5 percent by weight of polyethylene or polypropylene in tetrachloroethylene may be used.
  • the converging fluid or carrier after having deposited the insulating particles, is sucked through the discharge duct 10 and is discharged in a collecting tank or to the atmosphere, depending on whether it is a solvent or a gas and whether the recovery of which is necessary or convenient, or if it merely is air.
  • the fluid may also be passed through conventional purification or recovery systems for reuse.
  • Cooling fluid such as water
  • Cooling fluid is circulated in the cooling chamber 11 to maintain the duct 13 at the desired temperature, even though it is disposed in the zone of high temperature of the extruder head.
  • the insulation can be that suitable in view of the particular performance required for the waveguide to be extruded
  • the conveying fluid can be chosen among the liquid solvents or the gases which prove to be the most appropriate for the type of insulation, for the working temperatures or for other elements which may affect forming of the layer 15 or the characteristics of the end product.
  • the extruders head can have a configuration different from that described
  • the nozzle for spraying the fluid containing the charged particles can have a shape selected to provide the desired spray as a function of the insulating material, the fluid employed, the dimensions and shape of the tube 12 and the forward speed of the tube 12.
  • the shape of the sucking duct can be different from that indicated.
  • it can be annular or concentric with the axis of the inner mold.
  • the position of the spraying nozzle and of the suction opening can differ from those illustrated. For example, they could be reversed with respect to those described and hence, the spraying nozzle could be in a more peripheral position while the suction opening could be in a more central position.
  • a process for lining the interior of a conductive metal tube with a relatively thin layer of insulating material of uniform thickness comprising extruding metal of said tube heated to a temperature above the melting point of said insulating material in tubular form and advancing the so-formed tube as it is formed, applying said insulating material in a fluid carrier to the interior surface of said tube as it is so formed and advanced and at circumferential portion on said surface spaced from the point of extrusion and that has stabilized in form but which is at a temperature above the melting point of said insulating material by projecting the insulating material in said carrier radially toward said portion from within said formed tube and in a spray pattern uniformly distributed around the axis of said tube but spaced therefrom and evacuating the fluid carrier remaining after the insulating material has been deposited on said surface from within said tube.
  • said insulating material is selected from the group consisting of polyethylene and polypropylene and wherein said carrier is selected from the group consisting of nitrogen, dichlorodifluoromethane and tetrachloroethylene.
  • Apparatus for manufacturing a conductive tube having a relatively thin interior lining of insulating material of uniform thickness comprising an extruder for extruding metal heated to a temperature above the melting point of said insulating material and having an extrusion outlet in the shape of said tube for forming said tube, spray means within said extruder and extending beyond said extrusion outlet in the direction of extrusion for spraying said insulating material in a fluid carrier on the interior surface of said tube and as it is extruded, said spray means comprising an annular outlet spaced from said extrusion outlet in said direction and disposed adjacent said interior surface of said tube for directing said insulating material in said carrier radially toward said interior surface, said annular outlet extending around but being spaced from the axis of said tube, and a passageway extending through said extruder and communicating with said annular outlet for supplying said insulating material in said carrier to said annular outlet, and evacuating means within said extruder and extending beyond said extrusion outlet in said direction for
  • passageway of said spray means and said passageway of said evacuating means are formed by a pair of coaxial ducts, a pair of walls of said ducts being spaced from each other and forming a cooling chamber therebetween for the circulation of cooling fluid between said ducts.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
US18666A 1969-04-05 1970-03-11 Process and apparatus for lining conductive tubes with insulating material Expired - Lifetime US3643727A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT1514869 1969-04-05

Publications (1)

Publication Number Publication Date
US3643727A true US3643727A (en) 1972-02-22

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Family Applications (1)

Application Number Title Priority Date Filing Date
US18666A Expired - Lifetime US3643727A (en) 1969-04-05 1970-03-11 Process and apparatus for lining conductive tubes with insulating material

Country Status (4)

Country Link
US (1) US3643727A (de)
DE (1) DE2015477A1 (de)
FR (1) FR2060001B1 (de)
GB (1) GB1274818A (de)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4884960A (en) * 1988-05-06 1989-12-05 Allied-Signal Inc. Die for extruding and wash coating
US4899516A (en) * 1987-10-07 1990-02-13 Robert Bosch Gmbh Sealing device for two-piece capsules
US6026731A (en) * 1997-07-29 2000-02-22 Luk Fahrzeug-Hydraulik Gmbh & Co. Kg Compressor for automotive air-conditioning system
US6599451B2 (en) * 2001-02-13 2003-07-29 Hans G. Franke Rotating extrusion die with spray nozzle
US7014808B2 (en) * 2002-03-05 2006-03-21 The Coca-Cola Company Method and apparatus for coating the interior surface of a straw
US20100093903A1 (en) * 2008-09-19 2010-04-15 Gerhard Spies Sprayable composition
US20100285216A1 (en) * 2008-02-06 2010-11-11 Reginald Bourne Apparatus and method for internally lining an elongate member
US20100326352A1 (en) * 2009-06-25 2010-12-30 Xerox Corporation Apparatus for applying an acoustic dampening coating to the interior of a xerographic drum

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1730638A (en) * 1928-04-20 1929-10-08 Goodrich Co B F Method and apparatus for dusting the interiors of tubes
FR993277A (fr) * 1949-06-16 1951-10-29 Telecommunications Sa Conducteur creux à transmission à haute fréquence
US3022552A (en) * 1959-08-24 1962-02-27 Alfred H Tessmann Continuous casting apparatus
US3422795A (en) * 1965-12-13 1969-01-21 Millard F Smith Apparatus for coating hollow objects with powder

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2663652A (en) * 1950-03-04 1953-12-22 Du Pont Process for coating with polyethylene
GB746179A (en) * 1952-12-24 1956-03-14 Telegraph Constr & Maintenance Improved method of and apparatus for coating articles with plastic substances
NL277060A (de) * 1961-04-14

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1730638A (en) * 1928-04-20 1929-10-08 Goodrich Co B F Method and apparatus for dusting the interiors of tubes
FR993277A (fr) * 1949-06-16 1951-10-29 Telecommunications Sa Conducteur creux à transmission à haute fréquence
US3022552A (en) * 1959-08-24 1962-02-27 Alfred H Tessmann Continuous casting apparatus
US3422795A (en) * 1965-12-13 1969-01-21 Millard F Smith Apparatus for coating hollow objects with powder

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4899516A (en) * 1987-10-07 1990-02-13 Robert Bosch Gmbh Sealing device for two-piece capsules
US4884960A (en) * 1988-05-06 1989-12-05 Allied-Signal Inc. Die for extruding and wash coating
US6026731A (en) * 1997-07-29 2000-02-22 Luk Fahrzeug-Hydraulik Gmbh & Co. Kg Compressor for automotive air-conditioning system
US6599451B2 (en) * 2001-02-13 2003-07-29 Hans G. Franke Rotating extrusion die with spray nozzle
US20030211187A1 (en) * 2001-02-13 2003-11-13 Franke Hans G. Rotating extrusion die with spray nozzle
US7008204B2 (en) * 2001-02-13 2006-03-07 Amylex Corporation Rotating extrusion die with spray nozzle
US7014808B2 (en) * 2002-03-05 2006-03-21 The Coca-Cola Company Method and apparatus for coating the interior surface of a straw
AU2003216490B2 (en) * 2002-03-05 2008-01-10 The Coca-Cola Company Method and apparatus for coating the interior surface of a straw
US20100285216A1 (en) * 2008-02-06 2010-11-11 Reginald Bourne Apparatus and method for internally lining an elongate member
US8640642B2 (en) * 2008-02-06 2014-02-04 Reginald Charles Bourne Apparatus and method for internally lining an elongate member
US20100093903A1 (en) * 2008-09-19 2010-04-15 Gerhard Spies Sprayable composition
US20100326352A1 (en) * 2009-06-25 2010-12-30 Xerox Corporation Apparatus for applying an acoustic dampening coating to the interior of a xerographic drum
US9004003B2 (en) * 2009-06-25 2015-04-14 Xerox Corporation Apparatus for applying an acoustic dampening coating to the interior of a xerographic drum

Also Published As

Publication number Publication date
GB1274818A (en) 1972-05-17
DE2015477A1 (de) 1971-02-25
FR2060001B1 (de) 1973-08-10
FR2060001A1 (de) 1971-06-11

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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