EP0054374B1 - Electrode de bougie et procédé pour sa fabrication - Google Patents

Electrode de bougie et procédé pour sa fabrication Download PDF

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Publication number
EP0054374B1
EP0054374B1 EP81305642A EP81305642A EP0054374B1 EP 0054374 B1 EP0054374 B1 EP 0054374B1 EP 81305642 A EP81305642 A EP 81305642A EP 81305642 A EP81305642 A EP 81305642A EP 0054374 B1 EP0054374 B1 EP 0054374B1
Authority
EP
European Patent Office
Prior art keywords
metal
billet
shaped
cup
extrusion
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.)
Expired
Application number
EP81305642A
Other languages
German (de)
English (en)
Other versions
EP0054374A2 (fr
EP0054374A3 (en
Inventor
Kenneth Howard
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.)
FLOFORM LIMITED
Original Assignee
FLOFORM Ltd
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 FLOFORM Ltd filed Critical FLOFORM Ltd
Publication of EP0054374A2 publication Critical patent/EP0054374A2/fr
Publication of EP0054374A3 publication Critical patent/EP0054374A3/en
Application granted granted Critical
Publication of EP0054374B1 publication Critical patent/EP0054374B1/fr
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C23/00—Extruding metal; Impact extrusion
    • B21C23/22—Making metal-coated products; Making products from two or more metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/39—Selection of materials for electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T21/00—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs
    • H01T21/02—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs of sparking plugs

Definitions

  • This invention relates to a method of making a spark plug centre electrode having an inner core of a metal which has good thermal conductivity relative to the metal of an outer sheath fully enclosing the inner core, the outer sheath being formed of a corrosion resistant material.
  • a spark plug electrode in which an inner core of a metal having good thermal conductivity, for example copper, is partly encased within a sheath of a metal having good corrosion resistance properties, such as for example nickel or a nickel alloy.
  • a metal having good corrosion resistance properties such as for example nickel or a nickel alloy.
  • the purpose of using a composite electrode of this type is that, while good heat conduction is required of the electrode in order to prevent undue "burning", it is also necessary to provide for a hardwearing portion of the electrode at and around the point where sparking occurs.
  • the advantage of a composite electrode as described is that a material suitable for good heat conduction is used in conjunction with a material having suitably hardwearing properties.
  • GB-A-754,591 discloses a method of making a spark plug electrode in which a billet of copper is placed on top of a billet of nickel, the composite billet then being extruded through a suitable die to form a spark plug electrode having at one end a core of metal having good thermal conductivity surrounded by a sleeve of the corrosion resistant metal.
  • a method of making a centre electrode for a spark plug is taught in DE-A-2238283 which involves forming a composite billet from a core billet of copper that fits into a cup-shaped billet of nickel and then extruding the composite billet to form an elongate rod-shaped extrusion whose tip portion consists solely of nickel and an intermediate portion of which consists of copper sheathed with nickel. But at the base of the electrode is exposed copper which is undesirable because it does not facilitate welding to a wire connector by electric butt welding or friction welding.
  • a further object of the invention is to provide a centre electrode for a spark plug which can be easily formed at one end to provide a shoulder for mounting in the body a spark plug.
  • a centre electrode for a spark plug of the type having a core 12 of a first metal within a sheath 10 of a second metal, the first metal having a thermal conductivity higher than that of the second metal and a melting point lower than that of the second metal, the second metal being resistive to the corrosive environment in which the electrode works
  • inserting a billet 12 of the first metal within a cup-shaped billet 10 of the second metal and extruding the composite billet to form an elongate rod-shaped extrusion a tip portion of which consists solely of the second metal and an intermediate portion of which consists of said first metal enclosed in said second metal characterised in that:
  • the heating of the first and second metals may conveniently take place in a reducing atmosphere within a radiant furnace, the cup-shaped billet of the second metal being held in a suitably shaped black body so that conduction of heat from the radiant furnace occurs through the black body in order to melt the billet of said first contained within the cup-shaped billet of the second metal.
  • the melting of the billet of said first metal may be just sufficient to wet the interfaces thereof with the cup-shaped second metal or the whole of the first metal may be melted but, in any event, the first and second metals become united at their interfaces to form a unitary composite billet after cooling.
  • the extrusion of the composite billet can occur with a single blow to form an elongate rod-shaped extrusion having a core of the first metal enclosed substantially entirely within a sheath of the second metal, the side-wall of which is generally thicker in the regions above the end of the copper core than in the region adjacent to this core to provide a suitable volume of the nickel alloy at one end for forming a shoulder thereon.
  • the composite extrusion may be cropped off at one end and the shoulder formed at that end in order to provide mounting means for mounting in the ceramic insulator of a spark plug.
  • the first metal could be copper and the second metal could be a nickel alloy.
  • the composite electrode may conveniently be welded to a wire connector by electric butt welding in a known manner, or may be friction welded.
  • a cup shaped billet 10 of a heat resistant nickel alloy is of substantially cylindrical shape and has a cylindrical cavity 11 in which has been inserted a copper billet 12, the copper billet having been cropped-off from a length of copper wire (not shown).
  • the cup-shaped billet 10 has a frusto-conical portion 13 at one end thereof comprised solely of nickel alloy.
  • Figure 2 is shown a part-sectional view of a rectangular black body 14 of carbon, having a plurality of apertures 15 of cross-sectional shape corresponding substantially to the cross-sectional shape of billet 10.
  • the copper billet 12 is shown contained within a cup-shaped billet 10.
  • the copper billet 12 has been melted within the cylindrical part 11 of cup-shaped billet 10 by conduction of heat from a radiant furnace (not shown).
  • the meniscus 16 is of concave section, the peripheral edge of which is joined to the inner surface of billet 10.
  • the cup-shaped billet 10 is shown contained within an extrusion die 17 having a cylindrical section 18 of internal diameter corresponding substantially to the external diameter of the billet 10.
  • a converging portion 19 corresponds substantially to the frusto-conical portion of billet 10.
  • An extrusion punch 20 having a frusto-conical end 21 is capable of axial movement downwardly in order to extrude the billet 10 containing the melted copper billet 12 through an extrusion nozzle 22 provided with a clearance 23 of cylindrical shape.
  • Figure 5 is shown the extruded billet having an inner core 12 of copper and an outer sheath 10 of nickel alloy substantially entirely enclosing the inner core 12.
  • a flanged head 24 comprised solely of the nickel alloy is formed at one end of the extruded billet 10 which meets at junction 25 to substantially enclose the core 12.
  • the other end of the extruded billet 10 is comprised solely of the nickel alloy, the nickel alloy of this end corresponding generally to the nickel alloy contained within the frusto-conical portion 19 of the billet 10 prior to extrusion.
  • the cup-shaped biiiet 10 containing the copper billet 12 is placed within a correspondingly shaped recess in the black body 14, which is of carbon, and heated in a radiant furnace having a reducing atmosphere to a temperature at or above the melting point of the copper billet so as to cause melting of the copper billet 12 within the cup-shaped billet 10 to form a composite billet as shown in Figure 3.
  • the composite billet 10, 12 is then placed in the extrusion press as shown in Figure 4 and extruded, by pressure exerted on the billet via punch 20, through nozzle 22 to the shape of a composite electrode as shown in Figure 5.
  • this composite electrode consists of a cigar-shaped inner core 12 of copper and an outer sheath 10 of nickel alloy which substantially entirely encloses the inner core 12 by virtue of part of the metal of cup-shaped billet 10 meeting at 25 subsequent to extrusion.
  • the flanged portion 24 is cropped-off by a cropping machine and a shoulder portion 26 is then formed on this cropped-off end of the billet 10, the shoulder 26 being comprised solely of the nickel alloy.
  • a wire element 27 can then be butt welded to the electrode in any known manner, for example by electric butt welding or friction welding to form a welded junction at 28.
  • a centre electrode is provided according to the invention having closely controlled thermal characteristics which can be simply manufactured and yet is suitable for connection with a wire element as described above.
  • electrodes of different lengths and with different amounts of copper core can be produced by appropriate variations in the volume of copper placed in the cup; and the ratio of cross-section of the copper and nickel alloy composite is determined by the ratio of cylindrical bore to outside diameter of the nickel alloy cup-shaped billet.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Spark Plugs (AREA)

Claims (6)

1. Procédé pour fabriquer une électrode centrale pour une bougie d'allumage du type comportant un noyau 12 d'un premier métal dans une gaine 10 d'un second métal, le premier métal présentant une conductibilité thermique supérieure à celle du second métal et un point de fusion inférieur à celui du second métal, le second métal résistant au milieu corrosif dans lequel l'électrode travaille, suivant lequel on introduit une billette (12) du premier métal dans une billette en forme de cuvette (10) du second métal et on extrude la billette composite pour former une longue pièce extrudée en forme de broche dont une extrémité est constituée uniquement du second métal et dont une partie intermédiaire est constituée du premier métal enfermé dans le second métal, caractérisé en ce que:
(a) on chauffe les deux billettes (10, 12) ensemble jusqu'à une température égale ou supérieure au point de fusion du premier métal, mais inférieure au point de fusion du second métal;
(b) la quantité du premier métal (12) dans la billette composite est telle que lorsque ce métal est fondu, il occupe moins de la totalité de la profondeur de la cuvette dans la billette (10) du second métal;
(c) on refroidit les deux métaux à une température inférieure au point de fusion du premier métal pour former une billette composite dans laquelle le premier et le second métal sont unis au niveau de leurs interfaces, et
(d) lorsque la billette composite est extrudée, la partie de base (24, 25) de la pièce extrudée en forme de broche résultante est formée essentiellement du second métal, le produit de l'extrusion étant un noyau du premier métal enfermé en substance complètement dans une gaine du second métal.
2. Procédé suivant la revendication 1, caractérisé, en outre, en ce que le stade de chauffage comprend le chauffage des deux billettes (10 et 12) dans une atmosphère réductrice dans un four à rayonnement, la billette en forme de cuvette (10) du second métal étant maintenue dans un corps noir (14) convenablement façonné de sorte que la conduction de la chaleur à partir du four à rayonnement s'effectue à travers le corps noir pour faire fondre la billette (12) du premier métal contenu dans la billette en forme de cuvette (10) du second métal.
3. Procédé suivant la revendication 2, caractérisé, en outre, en ce que la fusion de la billette (12) du premier métal est juste suffisante pour mouiller ses interfaces avec la billette en forme de cuvette (10) du second métal.
4. Procédé suivant l'une quelconque des revendications précédentes, caractérisé, en outre, en ce que le stade d'extrusion comprend l'extrusion de la billette composite du premier et du second métal d'un seul coup pour former la longue pièce extrudée en forme de broche comportant un noyau du premier métal enfermé en substance entièrement dans une gaine du second métal.
5. Procédé suivant l'une quelconque des revendications précédentes, caractérisé, en outre, en ce qu'on sectionne la pièce extrudée en forme de broche à une extrémité et on forme un épaulement (26) à cette extrémité pour fournir des moyens de montage destinés au montage dans le corps d'une bougie d'allumage.
6. Procédé suivant l'une quelconque des revendications précédentes, caractérisé, en outre, en ce que le premier métal est du cuivre et le second métal est un alliage de nickel.
EP81305642A 1980-12-10 1981-11-27 Electrode de bougie et procédé pour sa fabrication Expired EP0054374B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8039567 1980-12-10
GB8039567A GB2088753B (en) 1980-12-10 1980-12-10 Spark plug electrode

Publications (3)

Publication Number Publication Date
EP0054374A2 EP0054374A2 (fr) 1982-06-23
EP0054374A3 EP0054374A3 (en) 1982-07-21
EP0054374B1 true EP0054374B1 (fr) 1985-03-13

Family

ID=10517887

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81305642A Expired EP0054374B1 (fr) 1980-12-10 1981-11-27 Electrode de bougie et procédé pour sa fabrication

Country Status (7)

Country Link
EP (1) EP0054374B1 (fr)
AU (1) AU551102B2 (fr)
CA (1) CA1203510A (fr)
DE (1) DE3169299D1 (fr)
GB (1) GB2088753B (fr)
NZ (1) NZ199163A (fr)
ZA (1) ZA818375B (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4684352A (en) * 1985-03-11 1987-08-04 Champion Spark Plug Company Method for producing a composite spark plug center electrode
CN108270149A (zh) * 2016-12-30 2018-07-10 宁波卓然铱金科技有限公司 火花塞中心电极制造镍杯-铜芯合成机构

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB754591A (en) * 1953-06-06 1956-08-08 Bosch Gmbh Robert A method for the extrusion of rod-shaped or pin-shaped metal articles, particularly sparking plug electrodes
US3548239A (en) * 1968-09-03 1970-12-15 Champion Spark Plug Co Spark plug electrode construction
JPS48103445A (fr) * 1972-04-14 1973-12-25
DE2755120A1 (de) * 1977-12-10 1979-06-13 Atomic Energy Authority Uk Verfahren zur herstellung einer zuendkerzenelektrode
GB2024665B (en) * 1978-07-07 1982-08-11 Ford Motor Co Spark plug electrode manufacture
GB2037190B (en) * 1978-12-16 1982-08-25 Gkn Floform Ltd Manufacture of spark plug electrode

Also Published As

Publication number Publication date
EP0054374A2 (fr) 1982-06-23
GB2088753B (en) 1984-02-01
CA1203510A (fr) 1986-04-22
AU7813781A (en) 1982-06-17
DE3169299D1 (en) 1985-04-18
AU551102B2 (en) 1986-04-17
NZ199163A (en) 1984-09-28
GB2088753A (en) 1982-06-16
ZA818375B (en) 1982-11-24
EP0054374A3 (en) 1982-07-21

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