EP0858084A1 - Method for constructing armoured resistance elements, and resistance element obtained by the method - Google Patents

Method for constructing armoured resistance elements, and resistance element obtained by the method Download PDF

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Publication number
EP0858084A1
EP0858084A1 EP98100433A EP98100433A EP0858084A1 EP 0858084 A1 EP0858084 A1 EP 0858084A1 EP 98100433 A EP98100433 A EP 98100433A EP 98100433 A EP98100433 A EP 98100433A EP 0858084 A1 EP0858084 A1 EP 0858084A1
Authority
EP
European Patent Office
Prior art keywords
sheath
conductor
resistance element
constructing
applying
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.)
Withdrawn
Application number
EP98100433A
Other languages
German (de)
French (fr)
Inventor
Duilio Capraro
Roberto Colombo
Danilo Papa
Gino Sonego
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.)
IRCA SpA Industria Resistenze Corazzate e Affini
Original Assignee
IRCA SpA Industria Resistenze Corazzate e Affini
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 IRCA SpA Industria Resistenze Corazzate e Affini filed Critical IRCA SpA Industria Resistenze Corazzate e Affini
Publication of EP0858084A1 publication Critical patent/EP0858084A1/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/42—Heating elements having the shape of rods or tubes non-flexible
    • H05B3/48—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C1/00—Details
    • H01C1/02—Housing; Enclosing; Embedding; Filling the housing or enclosure
    • H01C1/028—Housing; Enclosing; Embedding; Filling the housing or enclosure the resistive element being embedded in insulation with outer enclosing sheath
    • H01C1/03—Housing; Enclosing; Embedding; Filling the housing or enclosure the resistive element being embedded in insulation with outer enclosing sheath with powdered insulation
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/42—Heating elements having the shape of rods or tubes non-flexible
    • H05B3/48—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material
    • H05B3/52—Apparatus or processes for filling or compressing insulating material in tubes

Definitions

  • This invention relates to a method for constructing armoured resistance elements, and a resistance element obtained by the method.
  • Methods for constructing armoured resistance elements are known. These methods generally involve inserting into a metal sheath a resistive conductor with its end conductor terminals projecting from said sheath, fixing the conductor with insulating material (granular MgO), then rolling the sheath to reduce its diameter and compact the insulating material. After annealing the resistance element to improve its bendability, a silicone oil is applied to the end of the insulating material. Two insulating spacers preferably of steatite are then applied to the ends of the sheath.
  • insulating material granular MgO
  • the solution of firstly applying the two spacers and then annealing the resistance element does not enable the sheath to be completely annealed (ie along its entire lenght) because the two spacers would burn, so prejudicing the bendability of the element.
  • the object of the invention is to eliminate these drawbacks by providing a method for constructing a resistance element which prior to its use maintains its hermetic seal with time.
  • the method for constructing armoured resistance elements comprises inserting into a steel sheath 2 a conductor 4 of ferro-nickel alloy so that both its ends project from the sheath.
  • Said conductor is maintained fixed within said sheath by an insulating material 6, preferably granular magnesium oxide.
  • the sheath is then rolled to reduce its diameter and compact the magnesium oxide. It is then annealed in an oxidizing furnace to improve the bendability of the sheath.
  • both ends of the insulating material 6 are impregnated with a dielectric fluid 8 in the form of silicone oil.
  • a mushroom-shaped teflon plug 10 having a head 11 which adheres to the silicone oil 8, and a shank 12 which emerges from the end of the sheath 2.
  • the sheath prepared in this manner is then swaged at its ends so that these assume a frusto-conical form to contact the shank 12 of the plug 10.
  • a traditional terminal 14 is then welded to the ends of the metal conductor.
  • the resistance element obtained by the method of the invention has the advantage of considerable resistance and sealing towards moisture during storage, and the ability to "transpire" during operation.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Thermistors And Varistors (AREA)
  • Resistance Heating (AREA)

Abstract

A method for constructing armoured resistance elements comprising the following steps:
  • inserting a resistive conductor (4), provided at its ends with conducting terminals, into a metal sheath (2),
  • fixing said conductor within said sheath by means of a granular insulating material (6),
    characterised by applying to each end of said sheath an elastically deformable plug (10) of dielectric material provided with a passage hole for the metal conductor, said plug partly projecting from said end, the ends of said sheath then being subjected to swaging.

Description

This invention relates to a method for constructing armoured resistance elements, and a resistance element obtained by the method.
Methods for constructing armoured resistance elements are known. These methods generally involve inserting into a metal sheath a resistive conductor with its end conductor terminals projecting from said sheath, fixing the conductor with insulating material (granular MgO), then rolling the sheath to reduce its diameter and compact the insulating material. After annealing the resistance element to improve its bendability, a silicone oil is applied to the end of the insulating material. Two insulating spacers preferably of steatite are then applied to the ends of the sheath.
These known resistance elements have however the drawback that with the passage of time, if left unused, they no longer provide a seal in that moisture can enter through gaps between the outer surface of the spacers and the sheath, to attack the magnesium oxide, which is hygrospic and hence loses its dielectric characteristics.
On the other hand, the solution of firstly applying the two spacers and then annealing the resistance element does not enable the sheath to be completely annealed (ie along its entire lenght) because the two spacers would burn, so prejudicing the bendability of the element.
The object of the invention is to eliminate these drawbacks by providing a method for constructing a resistance element which prior to its use maintains its hermetic seal with time.
According to the invention this object and further ones are attained through a method for constructing armoured resistance elements as described in claim 1.
A preferred embodiment of the present invention is described in detail hereinafter with reference to the accompanying drawings, on which:
Figure 1
is a longitudinal section through a resistance element on termination of the dielectric material insertion stage;
Figure 2
shows it in the same view as Figure 1 but provided with the insulating element;
Figure 3
shows it after swaging; and
Figure 4
is an enlarged view of the end part of the resistance element.
As can be seen from the figures, the method for constructing armoured resistance elements according to the invention comprises inserting into a steel sheath 2 a conductor 4 of ferro-nickel alloy so that both its ends project from the sheath.
Said conductor is maintained fixed within said sheath by an insulating material 6, preferably granular magnesium oxide. The sheath is then rolled to reduce its diameter and compact the magnesium oxide. It is then annealed in an oxidizing furnace to improve the bendability of the sheath.
On termination of this operation, both ends of the insulating material 6 are impregnated with a dielectric fluid 8 in the form of silicone oil. On this layer there is then applied a mushroom-shaped teflon plug 10 having a head 11 which adheres to the silicone oil 8, and a shank 12 which emerges from the end of the sheath 2. The sheath prepared in this manner is then swaged at its ends so that these assume a frusto-conical form to contact the shank 12 of the plug 10. A traditional terminal 14 is then welded to the ends of the metal conductor.
From the aforegoing it is apparent that, by virtue of the swaging operation, the resistance element obtained by the method of the invention has the advantage of considerable resistance and sealing towards moisture during storage, and the ability to "transpire" during operation.

Claims (5)

  1. A method for constructing armoured resistance elements comprising the following steps:
    inserting a resistive conductor (4), provided at its ends with conducting terminals, into a metal sheath (2),
    fixing said conductor within said sheath by means of a granular insulating material (6),
    characterised by applying to each end of said sheath an elastically deformable plug (10) of dielectric material provided with a passage hole for the metal conductor, said plug partly projecting from said end, the ends of said sheath then being subjected to swaging.
  2. A method as claimed in claim 1, characterised by effecting the following steps before applying the plugs of dielectric material:
    rolling the sheath to reduce its diameter and compact the insulating material,
    annealing the resistance element,
    applying to the ends of the sheath an insulating oil (8) to impregnate the granular insulating material.
  3. A method as claimed in claim 1, characterised by applying a substantially mushroom-shaped plug (10).
  4. A resistance element obtained by the method of claims 1 to 3, characterised by comprising:
    a sheath (2),
    a resistive conductor (4), provided at its ends with conducting terminals with their ends projecting from the sheath,
    an insulating support (6) which fixes said conductor within said sheath,
    end plugs (10) traversed by said conductor and partly projecting from said sheath.
  5. A resistance element as claimed in claim 4, characterised in that the plugs are of mushroom shape.
EP98100433A 1997-02-07 1998-01-13 Method for constructing armoured resistance elements, and resistance element obtained by the method Withdrawn EP0858084A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT97VE000005 IT1294562B1 (en) 1997-02-07 1997-02-07 ARMORED RESISTANCE AND RESISTANCE OBTAINED PROCEDURE.
ITVE970005 1997-02-07

Publications (1)

Publication Number Publication Date
EP0858084A1 true EP0858084A1 (en) 1998-08-12

Family

ID=11424236

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98100433A Withdrawn EP0858084A1 (en) 1997-02-07 1998-01-13 Method for constructing armoured resistance elements, and resistance element obtained by the method

Country Status (2)

Country Link
EP (1) EP0858084A1 (en)
IT (1) IT1294562B1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1448023A1 (en) * 2003-02-13 2004-08-18 Ngk Spark Plug Co., Ltd. Method for manufacturing sheathed heater and method for manufacturing glow plug
WO2008137101A1 (en) * 2007-05-04 2008-11-13 Xtreme Bolting Service, Inc. Compact, portable resistance heating device
WO2011036105A1 (en) * 2009-09-25 2011-03-31 E.G.O. Elektro-Gerätebau GmbH Tubular heater and method for production of such a tubular heater
DE112013002131B4 (en) 2012-04-20 2022-09-29 Sanden Holdings Corporation heater

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2021908A (en) * 1978-05-11 1979-12-05 Irca Spa Sealing the terminations of metal sheathed resistances
EP0010275A1 (en) * 1978-10-13 1980-04-30 Elpag Ag Chur Tubular heating element
US4314401A (en) * 1979-01-29 1982-02-09 Isamu Saku Sheathed heating element and sealing of sheathed electric heating element
EP0157182A1 (en) * 1984-03-01 1985-10-09 Elpag Ag Chur Tubular heating body
DE4235727A1 (en) * 1992-10-23 1994-04-28 Licentia Gmbh Waterproof termination for electrical tube heater - has heat resistant insulating body around terminal, pressing against internal seal and crimped by outer tube

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2021908A (en) * 1978-05-11 1979-12-05 Irca Spa Sealing the terminations of metal sheathed resistances
EP0010275A1 (en) * 1978-10-13 1980-04-30 Elpag Ag Chur Tubular heating element
US4314401A (en) * 1979-01-29 1982-02-09 Isamu Saku Sheathed heating element and sealing of sheathed electric heating element
EP0157182A1 (en) * 1984-03-01 1985-10-09 Elpag Ag Chur Tubular heating body
DE4235727A1 (en) * 1992-10-23 1994-04-28 Licentia Gmbh Waterproof termination for electrical tube heater - has heat resistant insulating body around terminal, pressing against internal seal and crimped by outer tube

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1448023A1 (en) * 2003-02-13 2004-08-18 Ngk Spark Plug Co., Ltd. Method for manufacturing sheathed heater and method for manufacturing glow plug
WO2008137101A1 (en) * 2007-05-04 2008-11-13 Xtreme Bolting Service, Inc. Compact, portable resistance heating device
US9062704B2 (en) 2007-05-04 2015-06-23 Xtreme Bolting Service, Inc. Compact, portable resistance heating device
US9289866B2 (en) 2007-05-04 2016-03-22 Xtreme Bolting Service, Inc. Compact, portable resistance heating device
WO2011036105A1 (en) * 2009-09-25 2011-03-31 E.G.O. Elektro-Gerätebau GmbH Tubular heater and method for production of such a tubular heater
EP2481259B1 (en) 2009-09-25 2015-07-01 E.G.O. ELEKTRO-GERÄTEBAU GmbH Tubular heater and method for production of such a tubular heater
DE112013002131B4 (en) 2012-04-20 2022-09-29 Sanden Holdings Corporation heater

Also Published As

Publication number Publication date
IT1294562B1 (en) 1999-04-12
ITVE970005A1 (en) 1998-08-07

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