US2749203A

US2749203A - Manufacture of decorative lamps

Info

Publication number: US2749203A
Application number: US234625A
Authority: US
Inventors: Robert F Hardwick
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1951-06-30
Filing date: 1951-06-30
Publication date: 1956-06-05
Anticipated expiration: 1973-06-05
Also published as: GB709865A; BE512437A

Description

June 5, 1956 F. HARDWICK MANUFACTURE OF DECORATIVE LAMPS Filed June 50, 1951 lVon-oxid/lz/hy Non-oxld/mhg Gas Gas Inventor: R/obert F HardwicK,

lw His Attorney.

MANUFACTURE OF DECORATIVE LAMPS Robert F. Hardwick, Euclid, Ohio, assignor to General Electric Company, a corporation of New York; patent dedicated to the Public insofar as it relates to lamps and lamp parts to the extent stated in document recorded in the United States Patent Oflice, January 4, 1954, Liber U438, page 394 Application June 30, 1951, Serial No. 234,625

3 Claims. (Cl. 316-18) My invention relates to a method of manufacturing electric incandescent lamps, and more particularly to a method of manufacturing lamps of the type having envelopes of decorative, ornamental or other irregular shape.

In the manufacture of electric incandescent lamps of the type provided with irregularly shaped decorative or ornamental envelopes in the form of, for example, lanterns, emblems, fruit objects, Santa Claus, etc., such as are suited for Christmas lighting, the usual practice heretofore has been to initially mold the glass lamp bulb to the desired final shape or configuration after which the customary lamp-making operations, such as the sealing-in of the mount, the exhaustion, gas filling and sealolf of the envelope, and the basing of the lamp, are then performed in the customary manner to complete the lamp. However, because of the irregular shape of the envelope, they are not suited for manufacture into finished lamps on conventional type automatic lamp-making equipment. Thus, the present bulb holders conventionally employed on lamp sealing-in machines would not hold such irregularly shaped bulbs in proper alignment with the exhaust tube or stem during the mount sealing-in operation and would result in excessive lamp shrinkage caused by voids in the seals, crooked seals, large seals, etc. Mechanical bulb holders employing a finger grip on the bulb have been proposed but they are complicated and uncertain in their operation and necessitate a substantial modifiction of existing lamp-making equipment which constitutes a considerable inconvenience and expense as Well as a time-consuming operation.

It is an object of my invention, therefore, to provide an improved method of fabricating an electric lamp of the type having an irregularly shaped envelope.

Another object of my invention is to provide an improved method of fabricating an electric lamp having an irregularly shaped bulb, which method lends itself to the manufacture of such lamps on existing conventional type automatic sealing-in machines provided with the customary type bulb holders.

Still another object of my invention is to provide a method of fabricating electric lamps of the type having an irregularly shaped bulb whereby the manufacture of such lamps on existing automatic lamp-making machinery, without interfering with the alternative use of such machinery for the manufacture of lamps with conventionally shaped bulbs, is rendered possible.

In accordance with the invention, glass bulbs of the conventional shape ordinarily employed in the manufacture of incandescent lamps'on automatic machinery, such as globular, tubular, or pear-shaped bulbs for instance, are first provided with a lamp mount which is sealed into the bulb, after which the entire portion of the bulb above the basing line thereof is heated to a pliable condition and then reshaped or molded into the desired final shape.

Further objects and advantages of my invention will appear from the following detailed description of species thereof and from the accompanying drawing in which;

Figs. l5 illustrate the successive steps involved in the nited States PatentO 2 manufacture, according to the method of my invention, of an electric incandescent lamp having a bulb of irregular shape;.Fig. 6 is an elevation of the completed lamp; and Figs. 7 to 9 illustrate the steps involved in manufacturing a modified form of electric incandescent lamp according to the method of the invention.

' Referring to the drawings, Figs. 1-5 illustrate the application of the invention to the manufacture of electric incandescent lamps by the well-known butt-seal method, As shown in Fig. 1, the first step according to the invention is the butt-sealing of a mount 1 and a glass exhaust tube 2 to the neck end 3 of a glass bulb or envelope 4. In accordance with the invention, the bulb 4 may be of any conventional or regular shape (e. g., globular, tubular, or pear-shaped, etc.) such as is ordinarily employed in the manufacture'of electric incandescent lamps and which is well suited to be held in proper sealing position by the conventional type bulb holders commonly employed on automatic lamp sealing-in machines. The bulb 4 is held in a neck-up position in the holders (not shown) of the butt sealing-in machine, and the mount 1, comprising a pair of lead-in wires, 5,5 tied'together by a glass bead 6 and having laterally bent

outer end portions

7, 7 and connected at their inner ends to the opposite ends of a filament 8 of tungsten Wire, is inserted into the bulb 4 until the laterally bent

outer end portions

7, 7 of the lead-in wires rest against the-rim of the bulb neck 3. The end of a glass exhaust tube 2, substantially corresponding in diameter to the bulb neck 3, is then abutted against the rim of the bulb neck, after which the adjoining edges of the bulb neck 3 and exhaust tube 2 are suitably heated and softened, as by gas fires 9, until the glass edges fuse andseal together and embed the lead-in

wire portions

7, 7. During the sealing-in operation the bulb 4 and the exhaust tube 2 are preferably rotated in unison about their common axes, as indicated by the arrow, to assure uniform heating and fusion-sealing of the glass edges completely therearound.

After the sealing-in of the mount 1 and the tubulation of the bulb in the above-described manner, the exhaust tube 2 is then contracted at a point immediately outward of the butt seal, as indicated at 2'. As shown in Fig. 2, this is accomplished by suitably heating and softening the glass of the exhaust tube 2 outwardly adjacent the butt seal, as by means of gas fires 10 directed thereagainst, and then raising or axially moving the exhaust tube away from the bulb to draw out and stretch the softened glass and thus contract or neck the tube so as to leave only a small diameter passageway therethrough for the subsequent evacuation of the bulb.

In accordance with the invention, the bulb 4 of the tubulated bulb assembly 11 is then re-molded or-reshaped to its final desired configuration. This operation may be conveniently performed on present automatic lamp-making equipment, to-wit, on the sealing-in machine, the exhaust machine, or the lamp transfer mechanism between such machines. The lamp reshaping operation is performed by suitably supporting the tubulated bulb assembly 11 in a bulb-down position, by means of theexhaust tube 2, so as to leave substantially the entire bulb 4 free or exposed for heating and reshaping. On the usual exhaust machine, as well as the transfer mechanism, the tubulated bulb assembly 11 is normally supported in such manner, the exhaust tube 2 being held in the customary compression rubber chuck 12 of the exhaust machine, as specifically illustrated in Figs. 3 and 4, or in the customary springclip holders of the transfer mechanism. In the case of the sealing-in machine, the bulb assembly 11 may be' supported by the same spring clip holders which are nor-' mally employed on such machines to hold the exhaust tubes in place during the butt-sealing thereof to the bulb, the said: exhaust tube holders being merely raised a sufficient distance to lift the bulb free of the associated bulb holders after completion of the butt-sealing operatron.

The bulb reshaping is accomplished in accordance with the invention by suitably heating the entire exposed portion of the bulb 4 more or less uniformly until it attains a pliable condition ready for reshaping. For this purpose the body portion of the bulb, from its basing line to its tip, may be flooded with relatively soft gas fires 13 (Fig. 3), the bulb meanwhile being rotated about its axis, as indicated by the arrow, to better assure the uniform heating of the bulb completely around its perimeter. During the heating of the bulb 4, the protruding lead-in

Wires

7, 7 and exhaust tube 2 are preferably shielded from the heat of the gas fires 13, as by means of a pair of normally separated, opposed, split-

cylindrical baflle members

14, 14 which close around and cover the outer lead-in wire portions '7, 7 and the exhaust tube 2 during the heating operation, as shown in Fig. 3. Also, during the heating and softening of the bulb it is supported against collapsing, and the filament 8 kept from being oxidized, by the in troduction into the bulb through the exhaust tube 2 of a suitable non-oxidizing gas (such as nitrogen, for example, or a mixture of nitrogen and hydrogen known in the lampmaking art as forming gas) at a relatively low pressure just suflicient to prevent such collapsing but insufficient to cause any appreciable expansion of the bulb. The supply line for such non-oxidizing gas is vented to the atmosphere through a valve so adjusted as to maintain the gas pressure within the bulb substantially constant or balanced at the above-mentioned pressure value at all times during the heating and softening of the bulb and up until the momcnt of reshaping, thereby eliminating any rise in gas pressure within the bulb (due to the heating and expansion of the gas therein during the heating operation) such as would prematurely expand the bulb.

When the glass of the bulb 4 has attained the desired degree of pliability the heating thereof is then discontinued, as by removal of the bulb from the gas fires 13 through indexing of the machine, and the heated gas-filled bulb then immediately enclosed in a mold 15 (Fig. 4) having a mold cavity 16 of the desired configuration, whereupon an additional amount or puff of such non-oxidizing gas, at a higher pressure than that employed to support the bulb against collapsing, is immediately introduced into the bulb through the exhaust tube 2 to expand and blow the pliable wall of the bulb to the shape of the mold cavity 16. As shown, the mold 15 may be formed in two

half sections

17, 17 which are normally separated to permit positioning of the bulb therebetween and which are subsequently closed to surround the bulb and form the mold cavity 16. After the passage of a sufficient length of time to permit setting of the softened glass of the bulb 4, the mold sections 17 may be separated and the bulb removed therefrom. Where the delay required for the glass to thus harden in the mold is objectionable, as where it is desired to increase the production rate of the machine employed to reshape the bulb by removing the reshaped bulb from the mold before the softened glass of the bulb has fully set or hardened, then in such case the gas pressure within the bulb is released or reduced to a lower pressure approximately corresponding to that of the ambient before the mold is opened in order to prevent expansion of the still soft glass bulb by the gas pressure therein. Thereafter, non-oxidizing gas, such as that previously mentioned, is introduced into the bulb in the same manner as before, through a vented supply line, at the proper low pressure to preserve the shape of the re-molded bulb and prevent oxidation of the filament, until the glass of the bulb has completely set. During the cooling of the bulb following its removal from the mold it is suitably annealed, as by directing soft gas fires thereagainst, to remove the strains in the glass.

After having been reshaped in the above manner, the lamp bulb assembly 11 is put through the usual further lamp-making operations (i. e., evacuation, tipping-off and basing) which are required to complete the fabrication thereof into a finished lamp. The evacuation of the bulb is carried out on a conventional type lamp exhaust ma chine, the exhaust tube 2 being sealed or tipped-off at the construction 2 thereof after the evacuation operation has been performed. As shown in Fig. 5, the exhaust tube 2 is tipped-off by gas fires 1S directed against the contracted region 2' of the tube. The sealed-off bulb 4 is then provided with a suitable base 19 cemented or othersuitably fastened to the bulb, and the lead-in

wires

7, 7 connected to the terminals 20, 21 thereof, to thereby complete the fabrication of the bulb assembly 11 into a finished lamp, as shown in Fig. 6.

Figs. 7 to 9 illustrate the application of the invention to the manufacture of decorative incandescent lamps by the flange seal method wherein a glass stem type lamp mount 22, comprising a glass stem tube 23 provided with an exhaust tube 24 and having lead-in wires 25, 25' sealed therethrough and supporting a filament 26, is sealed into the neck end 27 of the glass lamp bulb 28. In the manufacture of such a type lamp in accordance with the invention, a glass bulb 28 of any conventional circular section shape such as is ordinarily employed in the manufacture of electric incandescent lamps and having an extended or long neck 29, is held upright, in a neck-down position, in the holders (not shown) of a conventional type lamp sealing-in machine, and the mount 22 is supported in proper sealing position within the bulb neck 29, as shown in Fig. 7. The bulb neck 29 is then heated and fusion-sealed to the flange 30 of the stem tube 23 by means of gas fires 31 directed against the bulb neck at the region thereof opposite the flange 30, the outward end of the extended bulb neck 29 (i. e., the cullet as it is commonly known) being severed from the bulb by the gas fires 31 during the progress of the sealing-in operation.

Following the sealing-in of the mount 22 into the bulb 28 in the above manner, the sealed bulb assembly 32 is processed in the same manner as before, it being supported in an inverted position, as by means of the compression rubber chuck 12 of a conventional lamp exhaust machine, and the entire body portion of the bulb 2B flooded with relatively soft gas fires 13 (as shown in Fig. 8) until it attains a pliable condition, a suitable non-oxidizing gas meanwhile being introduced into the exhaust tube 24 at a relatively low pressure just sufficient to prevent collapsing of the softened bulb but insuflicient to expand it in any way. The softened bulb 28 is then immediately enclosed in a mold 15 having a mold cavity 1.6 of the desired configuration, and the bulb blown into the mold cavity by a puff of non-oxidizing gas introduced into the bulb through the exhaust tube 24. After hardening of the reshaped glass bulb 28, the bulb assembly 32 is removed from the mold 15 and then processed in the usual manner (i. e., exhausted, tipped-off and based) to thereby complete the fabrication thereof into a finished lamp.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. The method of fabricating a decorative electric lamp of complex shape which comprises forming a preliminary complete tubulated lamp bulb assembly of a glass bulb having a. simple shape of a body of revolution with a filament sealed therein and an exhaust tube projecting from a single opening therein and communicating with the interior of the bulb, and then, while supporting the said assembly by the exhaust tube only, heating substantially the entire surface of the bulb other than the seal thereof to a plastic condition and molding it to a complex decorative shape materially different from its initial shape by the introduction of fluid pressure into the bulb through said exhaust tube to expand the plastic portion of the bulb into a surrounding mold, and finally, while supporting the reshaped assembly by the said exhaust tube, evacuating the bulb through said exhaust tube and sealing and severing the exhaust tube at an area adjacent the bulb.

2. The method of fabricating a decorative electric lamp of complex shape which comprises forming a preliminary complete tubulated lamp bulb assembly of a glass bulb having a simple shape of a body of revolution With a filament sealed therein and an exhaust tube projecting from a single opening therein and communicating with the interior of the bulb, and then, while continuously supporting the said assembly by the exhaust tube only, performing thereon a sequence of operations comprising heating substantially the entire surface of the bulb other than the seal thereof to a plastic condition, introducing into said bulb during the heating thereof a non-oxidizing gaseous medium at a pressure sufficient to prevent collapsing of the bulb, molding the bulb to a complex decorative shape materially different from its initial shape by the introduction of a non-oxidizing gaseous medium under pressure into the bulb through said exhaust tube to expand the plastic portion of the bulb into a surrounding mold, and then evacuating the bulb through said exhaust tube and sealing and severing the exhaust tube at an area adjacent the bulb.

3. The method of fabricating a decorative electric lamp of complex shape which comprises forming a preliminary complete tubulated lamp bulb assembly of a glass bulb having a simple shape of a body of revolution with a filament sealed therein and an exhaust tube projecting from a single opening therein and communicating with the interior of the bulb, and then, while continuously supporting the said assembly by the exhaust tube only, performing thereon a sequence of operations comprising heating substantially the entire surface of the bulb other than the seal thereof to a plastic condition, introducing into said bulb during the heating thereof a filling of a nonoxidizing gas and maintaining the said gas filling at a substantially constant pressure suficient to prevent collapsing of but insufficient to expand the pliable bulb, molding the bulb in a mold to a complex decorative shape materially different from its initial shape by the introduction of a non-oxidizing gaseous medium under pressure into the bulb through said exhaust tube to expand the bulb to the shape of said mold, reducing the gas pressure within the bulb to a lower pressure approximately corresponding to that of the ambient, removing the reshaped bulb from the mold before the glass thereof has fully set, immediately introducing and maintaining in said bulb a gas filling of a non-oxidizing gas at a substantially constant pressure to preserve the shape of the bulb until the glass thereof fully sets, and then evacuating the bulb through said exhaust tube and sealing and severing the exhaust tube at an area adjacent the bulb.

References Cited in the file of this patent UNITED STATES PATENTS 2,235,515 Carpenter Mar. 18, 1941 2,491,237 Way Dec. 13, 1949 2,494,871 Greiner Jan. 17, 1950 FOREIGN PATENTS 7,697 Great Britain Apr. 2, 1903 284,046 Germany Oct. 10, 1912