US2067746A - Lamp filament and method of manufacture thereof - Google Patents

Lamp filament and method of manufacture thereof Download PDF

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Publication number
US2067746A
US2067746A US752016A US75201634A US2067746A US 2067746 A US2067746 A US 2067746A US 752016 A US752016 A US 752016A US 75201634 A US75201634 A US 75201634A US 2067746 A US2067746 A US 2067746A
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US
United States
Prior art keywords
mandrel
filament
convolutions
molybdenum
temperature
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
US752016A
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English (en)
Inventor
Rolland M Zabel
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.)
Hygrade Sylvania Corp
Original Assignee
Hygrade Sylvania Corp
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
Priority to BE412106D priority Critical patent/BE412106A/xx
Application filed by Hygrade Sylvania Corp filed Critical Hygrade Sylvania Corp
Priority to US752016A priority patent/US2067746A/en
Priority to GB29984/35A priority patent/GB465119A/en
Priority to FR797118D priority patent/FR797118A/fr
Application granted granted Critical
Publication of US2067746A publication Critical patent/US2067746A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • Y—GENERAL 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/4981—Utilizing transitory attached element or associated separate material

Definitions

  • Another feature relates to theuse of a molybdenum or similar refractory metal to form the primary convolutions of a doubly convoluted filament,-'and a mandrel of steel or other similar material to form the secondary convolutions of such filament.
  • a still further feature relates to the novel organization and succession of steps which enable doubly convoluted filaments to be wound and formed with accuracy and at low cost.
  • FIG. 1 is a magnified diagrammatic view to explain the manner of forming the primary convolutions of the filament.
  • Fig. 2 is a magnified diagrammatic view to explain the formation of the secondary convolutions of the filament.
  • Fig. 3 is a diagrammatic view with one of the mandrels removed.
  • Fig. 4 is a magnified diagrammatic view showing the finished filament.
  • Fig. 5 is a diagrammatic view illustrative of one form of mounted filament in accordance with the invention.
  • a filament of relatively high resistance which at the same time is capable of producing a high concentration of light.
  • doubly convoluted filaments have been employed wherein the wire constituting the filament is formed with initial convolutions of relatively small diameter, these convolutions being termed herein the primary convolutions; the initially coiled wire is then recoiled with relatively large convolutions which will be referred to herein as the secondary convolutions.
  • the primary convolutions 'as well as the secondary convolutions be as close together as is feasible.
  • both the primary convolutions and the secondary convolutions have a permanent set so that when the filament is in use at relatively high temperature there is little danger of the filament being distorted.
  • the primary coils of thefilament are wound and formed on a specially chosen mandrel having a predetermined temperature characteristic while the secondary convolutions are wound and formed on a mandrel having different characteristics from the first mandrel.
  • the wire I constituting the filament is wound in any well-known manner around a mandrel 2 of the proper diameter.
  • the wire I is of tungsten such as is ordinarily employed in the present day incandescent lamps. While the drawing shows the successive primary convolutions of the wire 'I relatively widely spaced, it will be understood that this is done merely for explanatory purposes and that any other spacing of the convolutions may be employed.
  • the mandrel 2 is preferably of molybdenum, is then wound around a second mandrel 3 of a different material preferably of steel or similar vnonrefractory material as indicated in Fig. 2 of the drawing.
  • the filament or wire I is doubly convoluted, the primary convolutions being formed by mandrel 2 and the secondary convolutions being formed by mandrel 3 of larger diameter.
  • the doubly convoluted filament together with the two mandrels is then fired or heated for a predetermined length of time for example about fifteen minutes to a temperature 'at which the molybdenum mandrel 2 is given a permanent set but preferably not to a temperature high enough to set the tungsten filament I,
  • this heating being preferably, although not necessarily, effected in a vacuum or mufile furnace.
  • the assembly of Fig. 2 may be heated to a temperature of approximately 1100 C. which is lower than the melting point of the nonrefractory mandrel, to achieve the setting of the mandrel 2 but at this temperature the tungsten wire 4 is not set.
  • the next step in the method is to remove the mandrel 3 as indicated in Fig. 3 of the drawing. This may be done by the usual method, known to the art and mentioned in United States Patent 1,599,241, issued September "I, 1926 to George Mery, of dissolving the mandrel in an acid.
  • An acid such as hydrochloric may be used, which will dissolve the steel mandrel without appreciably aiiecting the molybdenum one. Because of the previously set condition of the molybdenum mandrel 2 the coiled tungsten wire I is retained in shape after the removal of the steel mandrel.
  • the double convoluted tungsten filament I and its previously set molybdenum mandrel 2 are then fired for a short time, for example about two minutes, to a temperature at which the tungsten filament l is permanently set, for example the filament and the mandrel 2 may be heated to a temperature approximately 1650" C.
  • the assembly may be cooled and the mandrel 2 may be removed in any suitable manner'thus leaving the doubly convoluted tungsten filament I with the primary and secondary convolutions in their set condition.
  • the molybdenum mandrel 2 may be removed by dissolving it in a suitable solvent, such as a combination of four parts of nitric acid and one part of sulphuric acid, as shown in United States Patent 1,650,605, issued November 29, 1927 to P. A. Campbell.
  • a suitable solvent such as a combination of four parts of nitric acid and one part of sulphuric acid, as shown in United States Patent 1,650,605, issued November 29, 1927 to P. A. Campbell.
  • the acid solvent is preferably used at a temperature just below its boiling point. It will dissolve the molybdenum without, of course, afiecting the tungsten of the filament.
  • the molybdenum mandrel 2 tends to contract then this tendency may be compensated for, by winding the filament around the mandrel 3 with a fewer number of turns per inch so that when the assembly of Fig. 2 is fired to the higher temperature any contraction of the molybdenum mandrel will tend compensatively to increase the total number of turns thus producing the desired number of turns in the finished article.
  • the initial winding may be effected around the mandrel 3 with the number of turns desired in the finished article and then the turns may be held to a fixed length in such a way that the molybdenum mandrel I may tend to contract but will be unable to do so because the ends are being held at a fixed distance.
  • the doubly convoluted filament after being removed from the mandrel I may be mounted in any well-known manner on a press or other finished portion of a lamp envelope.
  • thefilament i is supported by a pair of wires 4 and 5 which are sealed into a press diagrammatically indicated by the numeral 6.
  • the finished filament may be given any desired shape other than the arcuate shape of Fig. 5.
  • the finished filament shown in Fig. 4 may be bent at appropriate points to provide reversely extending parallel sections as is well known in the art.
  • the method of forming a doubly convoluted filament which includes the steps of forming the primary convolutionson a mandrel having a lower setting temperature than the setting temperature of the filament, forming the secondary convolutions by winding the first mandrel with the primary convolutions thereon around a nonrefractory mandrel, heating the nonrefractory mandrel to set the first mandrel without setting the filament, removing the nonrefractory mandrel and heating the first mandrel and filament to a temperature to set the filament, and then removing the first mandrel.
  • the method of forming a doubly convoluted filament which includes the steps of forming the primary convolutions on a refractory wire mandrel, forming the secondary convolutions on a nonrefractory mandrel, heating the doubly convoluted filament while on said second mandrel to a temperature sufii'cient to set the refractory mandrel without setting the filament, removing the nonrefractory mandrel, heating the filament while on the refractory mandrel to a higher temperature to set said filament, and then removing the refractory mandrel.
  • the method of forming a doubly convoluted filament of refractory metal which includes the steps of forming the primary convolutions on a I molybdenum wire mandrel, forming the secondary convolutions on a second mandrel having a melting point lower than the setting temperature of the filament material, heating the second mandrel with the filament and the first mandrel thereon to a temperature only high enough to set the first mandrel, removing the second mandrel and then heating the first mandrel with the filament thereon to a higher temperature to set the filament, and then removing the first mandrel.
  • the method of forming a doubly convoluted filament of refractory metal which includes the steps of winding the filament on a molybdenum mandrel to form primary convolutions, winding. the molybdenum mandrel with the convolutions thereon around a nonrefractory mandrel, heating the nonrefractory mandrel with the doiibly convoluted filament thereon to a temperature in the neighborhood of 1100 C. to set the molybdenum mandrel alone, removing the nonrefractory mandrel, heating the molybdenum mandrel with the filament thereon to a temperature in the neighborhood of 1650 C., and then removing the molybdenum mandrel.
  • Themethod of forming a doubly convoluted tungsten filament which includes the steps of winding the filament around a molybdenum man-.. drel to form the primary convolutions, winding the molybdenum mandrel and the primary convolutions around a steel mandrel of larger diameter to form the secondary convolutions, heating ROLLAND M. ZABEL.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Resistance Heating (AREA)
US752016A 1934-11-08 1934-11-08 Lamp filament and method of manufacture thereof Expired - Lifetime US2067746A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE412106D BE412106A (xx) 1934-11-08
US752016A US2067746A (en) 1934-11-08 1934-11-08 Lamp filament and method of manufacture thereof
GB29984/35A GB465119A (en) 1934-11-08 1935-10-30 Improvements in the manufacture of coiled-coil filaments for incandescent electric lamps and the like
FR797118D FR797118A (fr) 1934-11-08 1935-10-31 Procédé pour fabriquer un filament de lampe à double convolution et produit en résultant

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US752016A US2067746A (en) 1934-11-08 1934-11-08 Lamp filament and method of manufacture thereof

Publications (1)

Publication Number Publication Date
US2067746A true US2067746A (en) 1937-01-12

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Family Applications (1)

Application Number Title Priority Date Filing Date
US752016A Expired - Lifetime US2067746A (en) 1934-11-08 1934-11-08 Lamp filament and method of manufacture thereof

Country Status (4)

Country Link
US (1) US2067746A (xx)
BE (1) BE412106A (xx)
FR (1) FR797118A (xx)
GB (1) GB465119A (xx)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2927299A (en) * 1954-05-20 1960-03-01 Fredrick L Lefebvre Heater tube mounting
US3110098A (en) * 1960-11-25 1963-11-12 Sylvania Electric Prod Manufacture of wire coils
US3213519A (en) * 1962-02-05 1965-10-26 Polaroid Corp Electric lamps
US3237285A (en) * 1963-02-26 1966-03-01 Bendix Corp High frequency low noise twt helix fabrication
US3247699A (en) * 1962-01-12 1966-04-26 Westinghouse Electric Corp Manufacture of multiply-coiled electrodes for discharge devices
US3253894A (en) * 1962-01-12 1966-05-31 Westinghouse Electric Corp Composite wire and wire coil adapted for use in fabricating multiply-coiled electrodes
US3363304A (en) * 1965-04-06 1968-01-16 Atomic Energy Commission Usa Method of fabricating zirconium-beryllium-eutectic wire
US3629914A (en) * 1970-03-10 1971-12-28 Westinghouse Electric Corp Method of making an elongated singly coiled filament and mounting it in a tubular incandescent lamp
US3729787A (en) * 1971-09-22 1973-05-01 Westinghouse Electric Corp Method and apparatus for manufacturing beaded filament-coil components for electric lamps
US3803708A (en) * 1973-02-16 1974-04-16 Matsushita Electric Ind Co Ltd Method for making a resistor
US3807005A (en) * 1971-07-14 1974-04-30 Hitachi Ltd Process for dissolving mandrel wire of a filament coil
US3863313A (en) * 1973-06-07 1975-02-04 Gte Sylvania Inc Manufacture of subminiature incandescent lamps
US3863314A (en) * 1973-06-07 1975-02-04 Gte Sylvania Inc Method of manufacturing miniature incandescent lamps
US5380230A (en) * 1991-12-11 1995-01-10 Philips Electronics North America Corporation Method of manufacturing a single-ended incandescent lamp

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2927299A (en) * 1954-05-20 1960-03-01 Fredrick L Lefebvre Heater tube mounting
US3110098A (en) * 1960-11-25 1963-11-12 Sylvania Electric Prod Manufacture of wire coils
US3247699A (en) * 1962-01-12 1966-04-26 Westinghouse Electric Corp Manufacture of multiply-coiled electrodes for discharge devices
US3253894A (en) * 1962-01-12 1966-05-31 Westinghouse Electric Corp Composite wire and wire coil adapted for use in fabricating multiply-coiled electrodes
US3213519A (en) * 1962-02-05 1965-10-26 Polaroid Corp Electric lamps
US3237285A (en) * 1963-02-26 1966-03-01 Bendix Corp High frequency low noise twt helix fabrication
US3363304A (en) * 1965-04-06 1968-01-16 Atomic Energy Commission Usa Method of fabricating zirconium-beryllium-eutectic wire
US3629914A (en) * 1970-03-10 1971-12-28 Westinghouse Electric Corp Method of making an elongated singly coiled filament and mounting it in a tubular incandescent lamp
US3807005A (en) * 1971-07-14 1974-04-30 Hitachi Ltd Process for dissolving mandrel wire of a filament coil
US3729787A (en) * 1971-09-22 1973-05-01 Westinghouse Electric Corp Method and apparatus for manufacturing beaded filament-coil components for electric lamps
US3803708A (en) * 1973-02-16 1974-04-16 Matsushita Electric Ind Co Ltd Method for making a resistor
US3863313A (en) * 1973-06-07 1975-02-04 Gte Sylvania Inc Manufacture of subminiature incandescent lamps
US3863314A (en) * 1973-06-07 1975-02-04 Gte Sylvania Inc Method of manufacturing miniature incandescent lamps
US5380230A (en) * 1991-12-11 1995-01-10 Philips Electronics North America Corporation Method of manufacturing a single-ended incandescent lamp

Also Published As

Publication number Publication date
GB465119A (en) 1937-04-30
FR797118A (fr) 1936-04-21
BE412106A (xx)

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