US1904105A - Nonsag helical tungsten filament and method of making it - Google Patents

Nonsag helical tungsten filament and method of making it Download PDF

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Publication number
US1904105A
US1904105A US26290A US2629025A US1904105A US 1904105 A US1904105 A US 1904105A US 26290 A US26290 A US 26290A US 2629025 A US2629025 A US 2629025A US 1904105 A US1904105 A US 1904105A
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US
United States
Prior art keywords
filament
tungsten
core
sag
helical
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 - Lifetime
Application number
US26290A
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English (en)
Inventor
Johannes Antonius Maria Liempt
Geiss Willy
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General Electric Co
Original Assignee
General Electric Co
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Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
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Publication of US1904105A publication Critical patent/US1904105A/en
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Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01K—ELECTRIC INCANDESCENT LAMPS
    • H01K3/00—Apparatus or processes adapted to the manufacture, installing, removal, or maintenance of incandescent lamps or parts thereof
    • H01K3/02—Manufacture of incandescent bodies

Definitions

  • the invention relates to a method of manufacturing non-sagging helically coiled filaments made of metal with a high melting point, such as tungsten.
  • a high melting point such as tungsten.
  • incandescent lamp industry it is customary to wind drawn tungsten wire into a helix on a core, such as a steel wire, and after the winding is completed to remove this core by chemical means, for instance, by means of hydrochloric acid.
  • the helically wound filaments obtained in this wa are then mounted by being hooked on the filament supports, and are then placed inside the bulb.
  • Incandescent lamps filled with inert gas and having tungsten filaments made and mounted in this way have the drawback when operated at usual commercial efiiciencies that the coiled filaments.
  • the object of this invention is to provide a method that eliminates this drawback of the coil sagging, and makes feasible the manufacture of helically coiled filaments that do not sag, even after having been in use for a long time, and that retain the original shap e of coil and spacing of the turns.
  • the manufacture of non-sagging coiled filaments of metal with a highmelting poigt, such as tungsten, for use in incandescent amps and in thermionic and similar apparatus is carried out by a process of recrystallizing the filament so as to produce in it 'a sag resisting crystalline structure before it is mounted in the incandescent lamp, thermionic apparatus, etc.
  • Tungsten which is drawn into wire and is so .prepared that it is capable of developing the sag resisting crystalline structure is preferred as material for the coiled filaments.
  • the temperature of recrystallization of tungsten is about 1500 C.,therefore, according to the invention, the helically coiled filaments of tungsten are heated without distor-,
  • the core may be made of molybd um, tantalum, zirconium, or of alloys of ese metals, or of any other material that has a high enough melting point.
  • the core can be removed from the helically coiled filament preferably by means of a chemical treatment. If the wire that serves as a core consists of molybdenum, or of an alloy of molybdenum with not too much tungsten, then according to the invention after heating the helical filament to the necessary tempera;
  • ture the core can be removed by means o a mlxture of concentrated sulphuric acid 5 one that occurs most often in the filament.
  • the core consists of .la previously known methods were found to sag less as the structure of the crystals is coarser, that is, as the average size of the crystals is larger. Therefore, the sag of the helical filaments made according to the method that is described here will also depend on the average size of the crystals and on how they are joined or interlocked. If
  • lamp will be used to mean not only lncandescent lamps, but also thermionic ap- I paratus, such as X-ray tubes, pliotrons, dynatrons,'kenetrons such as used in the radio .telegraphy and radiotelephony, and similar apparatus that contains a filament. Also in this description and in the claims the sag of a coiled filament will bemeasured in terms of the height of the segment of the circle of which the sagged coiled filament formspart of the circumference expressed as a percent-- age of the chord of the segment of filament will be understood from the following pr'ac The drawn tungsten wire suspended between adjacent supports.
  • Lamps made according to the invention contain a drawn helical filament consisting.
  • the method of carrying out the invention tical example. capable of developing the non-sag structure is wound upon a core of molybdenum wire in the form of a helix by the usual coiling machine. Then the coiled filament and the core are placed in a region of high temperature,over-1500 C. At the same time, the
  • heated filament and core must be in an atmosphere of indifierent gases, such as a mixture of hydrogen and nitrogen.
  • indifierent gases such as a mixture of hydrogen and nitrogen.
  • the helical filament, still wound on the core is' cut to the length required, as for instance, for the making of incandescent lamps of a certain kind.
  • the pieces of helical filament and core are laid'in a mixture of equal parts of concentrated sulphuric acid and strong nitric acid of which the specific gravity for instance is A or a solution of selenium oxychloride which chemically dissolves the molybdenum core and leaves the tungsten filament unchanged.
  • a wire of tantalum or of zirconium may be used as a core in the same way as molybdenum and removed by means of hydrofluoric acid.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Resistance Heating (AREA)
US26290A 1924-05-24 1925-04-27 Nonsag helical tungsten filament and method of making it Expired - Lifetime US1904105A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL234489X 1924-05-24

Publications (1)

Publication Number Publication Date
US1904105A true US1904105A (en) 1933-04-18

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ID=19780188

Family Applications (1)

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US26290A Expired - Lifetime US1904105A (en) 1924-05-24 1925-04-27 Nonsag helical tungsten filament and method of making it

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US (1) US1904105A (enrdf_load_html_response)
FR (1) FR595911A (enrdf_load_html_response)
GB (1) GB234489A (enrdf_load_html_response)
NL (2) NL20242C (enrdf_load_html_response)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2454318A (en) * 1943-04-24 1948-11-23 Westinghouse Electric Corp Method of fabricating electron discharge devices

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2454318A (en) * 1943-04-24 1948-11-23 Westinghouse Electric Corp Method of fabricating electron discharge devices

Also Published As

Publication number Publication date
GB234489A (en) 1926-03-18
FR595911A (fr) 1925-10-12
NL20242C (enrdf_load_html_response)
NL27188B (enrdf_load_html_response)

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