US3366826A - Incandescent lamp having stainless steel tie wires - Google Patents

Description

Jan. 30, 1968 N. J. I-QAINVONE E'II'AL 3,366,826

' TIE WIRES INCANDESCENT LAMP HAVING STAINLESS STEEL Fil ed March 2, 1966 INVENTORS Nicholas J. Roinone WITNESSES and Leo 0. Werner United States Patent 3,366,826 INCANDESCENT LAMP HAVING STAINLESS STEEL TIE WIRES Nicholas J. Rainone, Clifton, and Leo C. Werner, Cedar Grove, N.J., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed- Mar. 2, 1966, Ser. No. 531,129 6 Claims. (Cl. 313269) This invention relates to electric lamps and has particular reference to an improved support structure for the lead'in wires and filament of an incandescent lamp.

Due to the length of the inner sections of the lead-in wires utilized in certain types of incandescent electric lamps, such as the so-called CC6- and CC-8 type general lighting lamps in the 50 watt and higher ratings, it is necessary to strengthen or rigi-dify the lead-in wires to prevent the mount structure from being damaged or bent out of shape should the lamp be subjected to mechanical impacts during shipment or use. Heretofore, this has been accomplished by anchoring each of the lead-in wires to the arbor of the lamp stem with a so-called tie wire of molybdenum, one end of which is embedded in the glass arbor and the other end whereof is wrapped or looped around the lead-in conductor. While lamps utilizing such molybdenum tie wires are entirely satisfactory from a performance standpoint, molybdenum is rather expensive and, because of its hardness and stiffness, rapidly abrades the curling dies used to loop the ends of the tie wire around the leads requiring the frequent replacement of such dies on the mounting machines.

In view of the foregoing, it is the general object of the present invention to provide a lead wire-filament support structure for electric lamps or the like which is more economical and easier to fabricate than those used heretofore.

Another and more specific object is the provision of a mount assembly for an incandescent lamp having tie wires that reduce the overall cost of the lamp without detracting from either its performance quality or ability to withstand mechanical shock.

The foregoing objects, and other advantages which will become apparent as the description proceeds, are achieved in accordance with the present invention by fabricating the tie wires from a particular grade or type of stainless steel instead of molybdenum.

Specifically, it has been found that a stainless steel containing from about 14% to 18% by weight of chromium, about 0.05 to 0.12% by weight of carbon, and the balance iron (marketed by the Wilber B. Driver Co., Newark, N.J., under the trade name #430 Stainless) exhibits good shock-resistant properties, is devoid of any impurities that would contaminate the lamp, and also forms a strong bond with and is thus capable of being firmly embedded in the glass arbor of the stem. Since the tie wires are not in direct contact with the filament, they are able to withstand the temperatures which prevail within the lamp in the region of the arbor button where they are located.

A better understanding of the invention Will be obtained by referring to the accompanying drawing, where- FIGURE 1 is an elevational view of a 60 watt CC-6 general lighting type incandescent lamp embodying the invention, a portion of the lamp envelope being broken away to show the lamp mount; and

FIG. 2 is an enlarged elevational view of the upper portion of the lamp mount.

While the present invention can be used with advantage in any type of electrical device having an incandescible element that is supported by lead-in conductors which Patented Jan. 30, 1968 require auxiliary strengthening supports or tie wires, it is especially adapted for use in conjunction with electric incandescent lamps and has accordingly been so illustrated and will be so described.

In FIG. 1 there is shown a 60 watt general lighting lamp 10 having the usual glass envelope 12 that is sealed and contains a filament mountassembly 14. Included in this mount assembly are the customary lead-in conductors or wires 15 and 16, a filament 18 of coiled refractory wire (such as tungsten or the like) that is attached to the inner ends of the lead-in wires and bridges the space therebetween, and a vitreous or glass stem 20 through which the lead-in wires are sealed. The inner end of the stem 20 is formed into a press 21 which is hermetically sealed to the lead-in wires, and a glass arbor 22 extends upwardly from the stem press between the wires 15 and 16 to a point located a predetermined distance from the filament 18.

As is shown more particularly in FIG. 2, the end of the glass arbor 22 is flattened and formed into a button 23 in which the ends of the stainless steel tie wires 24 and 25 of the present invention are embedded. The tie wires extend laterally from the button and have their opposite ends looped around the respective lead-in Wires 15 and 16. The stainless steel tie wires are thus fastened to the lead-in conductors at points located between the filament 18 and the stem press 21. While the lead-in wires are generally fabricated from nickel-plated copper and are thus relatively stiff, their length is such that they can very easily be bent or deformed should the lamp receive a mechanical impact. The tie wires eliminate this danger by coupling the leads to the arbor 22 and thus rigidifying the entire mount assembly.

As is also shown in FIG. 2, an axially-extending molybdenum filament-support wire 26 may also be embedded in the button 22 and have its opposite end looped around the midpoint of the coiled-coil filament 18 in accordance with standard lamp-making practice.

It has been discovered that the tie wires must be fabricated from a particular type of stainless steelotherwise the lamp may become contaminated with impurities, the tie wire may not retain its rigidity under the relatively high operating temperatures which prevail within the lamp in the vicinity of the filament, or the tie wire may not form a strong bond with the glass button and will subsequently work free from the button with resultant weakening of the mount and possible lamp failure under shock conditions. A stainless steel which meets all of the foregoing critical requirements and has given excellent results, has the following composition: 14.00 to 18.00% by weight of chromium, from about 0.05 to 0.12% (max.) carbon and the balance iron (available as #430 Stainless from Wilber B. Driver Co., Newark, NJ).

Comparative performance tests and cost analyses have shown that lamps fabricated with stainless steel tie wires having the aforesaid composition are equivalent, from a quality standpoint, to lamps having molybdenum tie wires-but that the material cost of the tie wires, per se, is reduced by approximately As will be appreciated from the foregoing, the objects of the invention have been achieved insofar as the use of stainless steel tie wires provides a rugged high-quality mount assembly which is inherently easier to manufacture on a mass production basis and less expensive than the prior art mounts having molybdenum tie wires. Since stainless steel is not as stiff and abrasive as molybdenum, the invention affords the additional advantage of increasing the life of the curling dies used on the filamentmounting machines and, thus, reduces the maintenance cost of such machines.

While one embodiment has been shown in accordance with the patent statutes, it will be understood that various modifications in both the configuration and composition of the tie Wires can be made without departing from the spirit and scope of the invention.

We claim as our invention:

1. In an electric lamp or the like having an incandescible element that is mounted on a pair of spaced conductors of such length that they are deformable when the lamp is mechanically impacted, the improvement comprising a rigid elongated strengthening member that is fastened to one of said conductors, is anchored to an interior electrically-insulated part of the iamp structure, and i composed of a stainless steel that (1) is devoid of impurities which would contaminate the lamp, and (2) retains its rigidity at the temperatures which prevail within the lamp when the latter is energized.

Z. The improvement set forth in claim 1 wherein;

a part of said stainless steel strengthening member is embedded and anchored in a body of vitreous material that is located adjacent said conductors and constitutes an integral part of the mount structure sealed within the lamp,

said conductors comprise a pair of lead-in wires, and

said stainless steel is of a type that forms a strong bond with said body of vitreous material.

3. The improvement set forth in claim 1 wherein said stainless steel strengthening member contains from about 14% to 18% by weight of chromium, up to 0.12% by weight of carbon, and iron which comprises the remainder of the alloy.

4. A mount assembly for an electric incandescent lamp or the like comprising, in combination,

a vitreous stem,

a pair of deformable lead-in wires sealed through a part of said stem and extending therebeyond in spaced apart relationship,

an incondescible member fastened to and bridging the the spaced terminal portions of said lead-in wires, and

a pair of rigid stainless sttel tie wires anchored in said stem and fastened to the respective lead-in wires at points located between said incandescible element and the part of said stem through which said lead-in wires are sealed,

one end of each of said tie wires being looped around the associated lead-in Wire and the opposite ends of said tie wires being embedded in a part of said stem that is remote from the part thereof through which the lead-in wires are sealed,

said stainless steel being of a type which (1) is devoid of impurities which would contaminate the lamp, (2) retains its rigidity at the temperatures which prevail within the lamp when the latter is energized, and (3) forms a strong bond with the part of said stem in which it is partially embedded.

5. The mount assembly set forth in claim 4 wherein;

said incandescible element comprise a filament of refractory metal wire,

said stem is terminated by a press and an arbor that extends longitudinally from said press and between said lead-in wires,

said tie wires are embedded in said arbor, and

said lead-in wires are sealed through said stem press.

6. The mount assembly set forth in claim 4 wherein said stainless steel tie wires have the following composition:

Percent by weight (Ihromium 14.00 to 18.00 Carbon 0.05 to 0.12 Iron Balance References Cited UNITED STATES PATENTS 1,374,766 4/1921 Ozaki 313-271 1,615,654 1/1927 Ryder 313-278 2,425,865 8/1947 Cartun 313-279 3,007,074 10/1961 Swasey et al7 313-277 X FOREIGN PATENTS 714,761 9/1954 Great Britain.

JOHN W. HUCKERT, Primary Examiner.

R. F, POLISSACK, Assistant Examiner.

Claims (1)

1. IN AN ELECTRIC LAMP OR THE LIKE HAVING AN INCANDESCIBLE ELEMENT THAT IS MOUNTED ON A PAIR OF SPACED CONDUCTORS OF SUCH LENGTH THAT THEY ARE DEFORMABLE WHEN THE LAMP IS MECHANICALLY IMPACTED, THE IMPROVEMENT COMPRISING A RIGID ELONGATED STRENGTHENING MEMBER THAT IS FASTENED TO ONE OF SAID CONDUCTORS, IS ANCHORED TO AN INTERIOR ELECTRICALLY-INSULATED PART OF THE LAMP STRUCTURE, AND IS COMPOSED OF A STAINLESS STEEL THAT (1) IS DEVOID OF IMPURITIES WHICH WOULD CONTAMINATE THE LAMP, AND (2) RETAINS ITS RIGIDITY AT THE TEMPERATURES WHICH PREVAIL WITHIN THE LAMP WHEN THE LATTER IS ENERGIZED.

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