US3908251A - Method of making beaded filament coil - Google Patents

Method of making beaded filament coil Download PDF

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Publication number
US3908251A
US3908251A US460000A US46000074A US3908251A US 3908251 A US3908251 A US 3908251A US 460000 A US460000 A US 460000A US 46000074 A US46000074 A US 46000074A US 3908251 A US3908251 A US 3908251A
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US
United States
Prior art keywords
wire
glass
mandrel
slurry
coiling
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
US460000A
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English (en)
Inventor
Joseph A Roy
Gary C Bradway
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.)
GTE Sylvania Inc
Original Assignee
GTE Sylvania Inc
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 GTE Sylvania Inc filed Critical GTE Sylvania Inc
Priority to US460000A priority Critical patent/US3908251A/en
Priority to JP4474375A priority patent/JPS5629331B2/ja
Application granted granted Critical
Publication of US3908251A publication Critical patent/US3908251A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/06—Main electrodes
    • H01J61/067—Main electrodes for low-pressure discharge lamps
    • H01J61/0672—Main electrodes for low-pressure discharge lamps characterised by the construction of the electrode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/04—Manufacture of electrodes or electrode systems of thermionic cathodes

Definitions

  • Electrodes for fluorescent lamps generally comprise a coiled coil filament coated with an electron emissive coating.
  • a fine tungsten basket wire is coiled around a mandrel.
  • the mandrel consists of two parallel wires, a tungsten currentcarrying wire and a temporary wire that will eventually be dissolved in acid.
  • This coiling is then coiled again, around another mandrel that will also eventually be dissolved in acid.
  • the filaments are then placed in automatic feeds of lamp mount making equipment where they are fed to lamp mounts and secured in the support wires thereof.
  • the automatic feeds are usually vibratory in nature and a common problem occurring therein is entangling of the filaments. The entangling results from burrs on the wire, caused by the cutting operation, or from unraveling of the basket wire on the current carrying wire.
  • US. Pat. No. 3,736,458 discloses a method of reducing basket wire unraveling by winding the primary coiling on a noncircular secondary mandrel, either oval or egg-shaped.
  • US. Pat. No. 3,792,224 discloses a method of preventing filament entangling by melting the metal at the ends of the filament to provide fused metal beads.
  • the instant invention is an improvement over the latter in that glass embedments are provided at the ends of the filaments to prevent entanglement.
  • the glass embedments can be formed at much lower temperatures than fused metal beads. And there is about a 6 percent savings in tungsten wire, since the wire is not melted in forming the glass embedment.
  • FIG. 1 is an elevational view of a coiled coil filament in accordance with this invention.
  • FIG. 2 is an enlarged view ofa portion of the secondary coiled wire prior to mandrel removal.
  • a filament l in accordance with this invention was made by coiling one mil tungsten wire 2 around a mandrel consisting of 2.2 mil tungsten wire 3 and 5.5 mil molybdenum wire 4 at 250 turns per inch. After heat treatment, the primary coiling was coiled on a secondary mandrel 5, which consisted of 16 mil molybdenum wire, at TPI.
  • Embedments 6 were formed by first coating the ends of the filament with a slurry of glass frit in a suitable liquid vehicle.
  • the slurry consisted of a low melting point glassfrit having an average particle size of 3 to 6 microns as measured by the Fisher sub-sieve sizer and having a composition of 2.6% ZnO, 22.5% SiO 27.8% B 0 9.1% Na O, 5.0% A1 0 and 9.0% BaO.
  • This glass has a softening temperature of 596C and a working temperature of about 900C.
  • the glass frit was dispersed in a 12 second ethylcellulose vehicle to a specific gravity of 1,620, the vehicle consisting of 2.9% by weight of N-type ethylcellulose, 4.4% dibutyl phthalate, 91.4% xylol and 1.3% butanol.
  • the slurry is applied to the end one or two turns of the filament by, for example, spraying or dipping. After the coating is dry, the filament is fired at a temperature, about 900C, high enough to volatilize and remove the organic material in the coating and to melt the glass frit, drawing it together to form embedment 6.
  • the glass frit slurry may be applied to the ends of the filament either before or after mandrels 4 and 5 are removed by dissolving in acid.
  • the slurry is applied before, since mandrel removal results in a cavity within the primary turns which can undesirably draw slurry therein by capillary action; it is desirable, for material efficiency purposes, that only a minimum amount of the filament be embedded by glass embedment 6.
  • the method of making nonentangling filaments for fluorescent lamps comprising the steps of: primary coiling tungsten wire on a mandrel comprising tungsten wire in parallel with a wire of a dissimilar metal; secondary coiling the wire and mandrel on a second mandrel; cutting the secondary coiling to predetermined lengths; and forming a glass embedment at each end of the predetermined lengths.
  • the glass embedment is formed by applying a glass frit slurry to said end, drying the applied slurry and firing the dried slurry to melt the glass frit therein.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Discharge Lamp (AREA)
US460000A 1974-04-11 1974-04-11 Method of making beaded filament coil Expired - Lifetime US3908251A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US460000A US3908251A (en) 1974-04-11 1974-04-11 Method of making beaded filament coil
JP4474375A JPS5629331B2 (enrdf_load_stackoverflow) 1974-04-11 1975-04-11

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US460000A US3908251A (en) 1974-04-11 1974-04-11 Method of making beaded filament coil

Publications (1)

Publication Number Publication Date
US3908251A true US3908251A (en) 1975-09-30

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Family Applications (1)

Application Number Title Priority Date Filing Date
US460000A Expired - Lifetime US3908251A (en) 1974-04-11 1974-04-11 Method of making beaded filament coil

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US (1) US3908251A (enrdf_load_stackoverflow)
JP (1) JPS5629331B2 (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4506187A (en) * 1981-06-12 1985-03-19 Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen Mbh Lamp filament structure, and method of its manufacture
US5729081A (en) * 1995-07-28 1998-03-17 Osram Sylvania Inc. Electrode coil for discharge lamps and method for producing such an electrode coil
KR100268203B1 (ko) * 1997-07-15 2000-10-16 김순경 가는 직경의 팔라멘트 권선 장치 및 그 방법

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0735178B2 (ja) * 1986-04-05 1995-04-19 大阪エヤゾ−ル工業株式会社 内容物混合装置およびそれを用いた内容物混合方法
JPS63198837U (enrdf_load_stackoverflow) * 1987-06-11 1988-12-21

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US274294A (en) * 1883-03-20 Incandescing electric lamp
AU217381B2 (en) * 1956-12-10 1957-06-13 N. V. Philips' Gloeilampenfabrieken Improvements in or relating to bifilarly wound heating filaments for cathodes of electric discharge tubes, and methods of manufacturing such filaments
US3778664A (en) * 1972-12-22 1973-12-11 Westinghouse Electric Corp Beaded coils for electric lamps and similar devices

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US274294A (en) * 1883-03-20 Incandescing electric lamp
AU217381B2 (en) * 1956-12-10 1957-06-13 N. V. Philips' Gloeilampenfabrieken Improvements in or relating to bifilarly wound heating filaments for cathodes of electric discharge tubes, and methods of manufacturing such filaments
US3778664A (en) * 1972-12-22 1973-12-11 Westinghouse Electric Corp Beaded coils for electric lamps and similar devices

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4506187A (en) * 1981-06-12 1985-03-19 Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen Mbh Lamp filament structure, and method of its manufacture
US5729081A (en) * 1995-07-28 1998-03-17 Osram Sylvania Inc. Electrode coil for discharge lamps and method for producing such an electrode coil
KR100268203B1 (ko) * 1997-07-15 2000-10-16 김순경 가는 직경의 팔라멘트 권선 장치 및 그 방법

Also Published As

Publication number Publication date
JPS5629331B2 (enrdf_load_stackoverflow) 1981-07-08
JPS5110684A (enrdf_load_stackoverflow) 1976-01-28

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