US1359134A - Stem and mount for incandescent-lamp filaments - Google Patents

Description

muted Nov., i6, 1920 P. WEMOHE. All@ IUNT FOR INCAYSCET LAMP HLAMENTS.

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TMORE 0F NEW'ARK, NE'W LEREY, ASSIG'NOR TO HYGRADE ENGE- lNG., A CORPQR-ATION'OF NEW' JERSEY.

STEM AND MOUNT NCMIDESCENT-LMEP FLAMENTS.

T o' all w Ito/mJ it may concern:

4a citizen of the United States ot America,

residing at Newark, county ci' Essex, State of Nen' Jersey, have invented certain ner.1 and useful Improvements 'in Steins and Mounts for incandescent-Lamp Filaments, of which the following is a specification.

My invention relates to incandescent lamps and comprises a special i'orxn of stem and arrangement of leading-in Wires for such lamps. lVhile my invention is applicable to any form of-incandescent electric lamp, its use is especially advantageous in the manufacture and use oli' small, high powered, tungsten filament lamps such as are used for automobile headlights, and in the manufacture and use no1e gas filled lamps. In lamps of these classes it has been customary to weld together two kinds of Wire to form the conductors passing Vfrom an external source of current supplyv through thev lamp stem, or seal, to the tungsten filament Within. rlhe inner sect-ion of eachV such wire is usually made oi nickel, the welded joint, or knot between the nickel and other sections being embedded in the glass of the seal. The inner ends of 'the nickel sections are usually iiattened and then bent around to form cups, or tube sections, into which the ends of the tungsten 'filament are set. Nickel is preferred for these inner sections because it is aii'ected less than other available metals, by the heat and gaseous reactions Within the lamp.

The making of these the flattening and the nickel sect-ions, are both rather delicate and costly operations, and the portion of solid nickel wire embedded in the seal is apt to crack the glass of the stem by its expansion under heat,-the coeiiicient oi" expansiongof nickel being much greater than that of glass. My present invention overcomes all these diiiiculties by employing short sections of nickel tube, instead 'of the solid nickel wires heretofore used, and by fastening such tube to the other tion by collapsing or pinching it on the same Welded joints and the telescoped end of the nickel tube in the glass of the stem forming the seal. The best construction at present known to me, made according to my invention, is illus- Specicaton of Letters Patent.

Patented Nov. i6, i920.

.application led July 18, 1918, Serial No. 245,442.

trated in the accompanying sheetot drawing in which,

Figure l is a side elevation of a com- I pleted (but unbased) lamp with parte broken away or shown in section, and

Fig. 2 is a Across section of the stem on the line 2-2 oi Fig. 1.

Throughout the drawings like reference characters indicate like parts: l, is the lamp bulb and 2 the glass stem, into, and through which the outer sections 3, 3, of the leadingin Wires are sealed. These are of seine metal or alloy which have substantially the same rate of expansion under heat as the glass of stein 2. The nickel tube sections 4,

il, are collapsed, or pinched down at 5,' 5, on

the wire sections 3, 3, telescoped into them, and also at their free ends 8, S, on the ends of the tungsten filament 7, to which they may be Welded, or cemented. Pieierably the pinched or collapsed tube sections 5, 5, do not extend along the entire telescoped sections of wires 3, 3, but the end portions of the tubes are left in their original circular shape, concentric with Wires 3, 3, With a ring shaped space 6, between, as indicated in Fig. 2.

The advantages of' my invention are obvious, By the use of an automatic machine these telescoped and pinched-'together leading-in Wires can be rapidly and accurately made from continuous lengths of Wire and ,cold drawn tubing, at much less cost and bending of the ends of- Wire secwith much less Waste, than the old Jorrn o'l solid AWire Welds could. be made. The cups for reception of the filament 7, formed by the fre-e ends of the tubes et, 4i, are much more pertect than the 4cups Jformed by flattening and rollingup' the ends of a solid nickel Wire, as in the old practice, and these cups when pinched down in 'the form shown at 8, 8, inake-a-be'tter joint with the filament l than do the flattened and curled ends of solid Wires; Finally, the telescoped but unpinclied ends of the nickel tubes embedded in the glass oic the stem 2, While irinly held thereby and so able to exert the full benefit of the stiffness ot their tubular formas supports :tor filament 7, are hollow, and expand and at one or more lpoints and then embedding contract radially less under heat than would solid wires oit the same diameter with co 5 sequent less tendency to 'crack the sea. Furthermore, such radial expansion of these thin tubes .as dries occur, exerts less buizsting force on the surrounding glass than. would the expanioii of a solid nickel wire, and may be entirely absorbed in the buckling 0i' bending of the thin tube Walls, insteadof resulting in a bursting out of the glass 'walls of the cavities in; Which the tubes' vtion above explained are preserved in substance.

Having described my invention, I claim:

An incandescent lamp stein and lainent mount which comprises in combination a stem otglass, a wire section sealed into said glass, 'and a section of metal tiibetelescopedand tting loosely over and pinched 2` on to the end of the Wire at a point soine distance from the end of the tube, an unpinclied portion extending in one direction a short way into the glass of tbe seal and iii the other direction beyond the end of tlie 2" wire to forni a cup, portions of the tube circumferencev not pinched being spaced away slightly ioin the telescoped wire.

MIN ER P. WETMORE.

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