US3796528A - Apparatus for manufacturing an electric lamp base that has a snag-proof terminal - Google Patents

Abstract

The peripheral edge of the metal eyelet that is embedded in the molded insulator of an electric lamp base is recessed behind the peripheral portion of the insulator, thus preventing the eyelet from being accidentally snagged and ''''lifted'''' or otherwise deformed during subsequent bulk processing and shipment of the bases. The protective peripheral portion of the insulator is formed during the molding operation by making the contactor portion of the eyelet smaller than the corresponding part of the die cavity and centrally positioning the eyelet within the cavity so that the molten glass (or other insulating material) is forced into the space between the peripheral edge of the contactor portion of the eyelet and the side walls of the molding die. Positioning and retention of the eyelet in the proper location within the die is automatically achieved by three spaced radially extending lugs (or axially extending pins) that are located at the bottom of the die cavity and form a pocket which receives eyelets that are fed into the die. A

Description

APPARATUS FOR MANUFACTURING AN ELECTRIC LAMP BASE THAT HAS A SNAG-PROOF TERMINAL Chrisman O. Smith, Paris, Tex.

Inventor:

731 Westinghouse Electric Corporation,

Pittsburgh, Pa. Filed: Apr. 28, 1972 Appl. No.: 248,481

Related U.S. Application Data Division of Ser. No. 47,294, June 18, 1970, which is a division of Ser. No. 742,417, July 3, 1968.

Assignee:

[56] References Cited UNITED STATES PATENTS 571,837 11/1896 Latham 425/127 X 2,304,461 12/1942 Knowles 425/123 2,030,132 2/1936 Apple 425/128 568,940 10/1896 Estabrooku 425/128 X 2,975,556 3/1961 Baird 65/49 X 2,519,328 8/1950 Whitmore et a1. 65/49. X 1,527,556 2/1925 Kadow 65/323 X FOREIGN PATENTS OR APPLICATIONS 7/1966 Australia....; 425/128 Mar. 12, 1974 Primary ExamirierJ. Spencer Overholser Assistant Examiner-John E. Roethel Attorney, Agent, or Firm---D. S. Buleza [57] ABSTRACT The peripheral edge of the metal eyelet that is embedded in the molded insulator of an electric lamp base is recessed behind -the peripheral portion of the insulator, thus preventing the eyelet from being accidentally snagged and lifted or otherwise deformed during subsequent bulk processing and shipment of the bases. The protective peripheral portion of the insulator is formed during the molding operation by making the contactor portion of the eyelet smaller than the corresponding part of the die cavity and centrally positioning the eyelet within the cavity so that the molten glass (or other insulating material) is forced into the space between the peripheral edge of the contactor portion Pit v texelt gsis w lls o themo tt e e Positioning and retention of the eyelet in the proper location within the die is automatically achieved by eyelet can also be used for this purpose 5 Claims, 11 Drawing Figures APPARATUS FOR MANUFACTURING ELECTRIC LAMP BASE THAT HAS A SNAG-PROOF TERMINAL CROSS-REFERENCE TO RELATED APPLICATIONS This application is a division of U.S. Pat. application Ser. No. 47,294, filed June 18, 1970, which application in turn is a division of U.S. Pat. application Ser. No. 742,417 filed July 3, 1968.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to electric lamps and has particular reference to an apparatus for manufacturing snag-proof bases for incadescent lamps for similar devices.

2. Description of the Prior Art As is well knowm, the bases used on general lighting type incandescent lamps are provided with a molded glass insulator which has a sheet metal eyelet embedded in its outer end. The flat circular portion of the eyelet is exposed at the end face of the insulator and serves as the end terminal or contactor for the lamp. A meduim-screw type base having such an insulator and eyelet is disclosed in U.S. Pat. No. 2,993,192 issued July 18, 1961, to R. W. Mouat. Another base of this type having an eyelet with a central portion that is dished inwardly to rigidify the sheet metal is disclosed in U.S. Pat. No. 2,987,696 issued June 6, 1961, to H.L. Rudler et al.

While the exposed circular portion of the eyelet in such prior art bases served satisfactorily as an end contact, it has been found that when the fabricated bases are shipped in bulk from the parts factory to the lamp plant (or from the base-making machine to the lamp-making machine in the same plant) the exposed peripheral edges of the eyelets interlock and become snagged-thus lifting the eyelets from the insulators cessed end contacts were constructed by, anchoring a flat metal disc in a previously formed circular recess in the end of the insulator. Thus, the attachment ofthe contactor disc to the preformed insulator was accomplished'by means of a separate time-consuming operation. The added cost and manufacturing difficulties inherent in such an operation make bases of this construction impractical and incompatible with the highspeed mass production techniques and machines employed throughout the industry today.

SUMMARY OF THE INVENTION The aforementioned problems and other disadvantages are circumvented in accordance with the present invention by utilizing an end terminal that is made from sheet metal and by positioning it relative to the base shell in a manner such that the peripheral edges of the terminal are recessed behind the outer rim of the insulator which is subsequently molded around and bonded to the ends of the shell and terminal.

Specifically, the sheet metal terminalcomprises an eyelet having a circular contact portion that is smaller in diameter than the bottom portion of the molding die. According to a preferred embodiment, a plurality of positioning members, such as three spaced lugs or the like that extend radially into the die cavity, are located at the bottom of the die and are dimensioned to form a pocket which nestingly receives the circular contact portion of the eyelet-thus properly orienting the eyelet. The peripheral end edges of this part of the eyelet are thus spaced from the sides of the die so that the glass (or other material from which the insulator is made) is forced into the intervening space and forms 'a series of integral arcuate' ledges on the end of the insulator which overlap the peripheral edges of the exposed circular portion of the eyelet and prevent the latter from being accidentally snagged and bent out of shape when the completed bases are being handled or processed. While edge portions of the eyelets are exposed by the notches left in the rim of the insulator by the positioning members in die, these notches are very narrow and do not present any difficulty as regards the snagging problem, especially since the edges of the eyelet are spaced a considerable distance inwardly from the outer surface of the insulator. Alternatively,-three axially extending pins or a single centrally disposed hollow pin can also be used as eyelet-orienting means within the die.

The invention accordingly provides a very simple and inexpensive solution to the eyelet-snagging and bending problem and one which permits the bases to be manufactured and subsequently assembled with the sealed-in lamps in the regular manner on high-speed lamp-making machines presently in use.

BRIEF DESCRIPTION OF THE DRAWING A better understanding of the invention will be obtained by referring to the exemplary embodiment shown in the accompanying drawing, wherein;

FIG. 1 is a side elevational view of a general lighting incandescent lamp having a base manufactured in accordance with the present invention;

FIGS. 2 and 3 are enlarged plan and longitudinal sectional views of the lamp and base shown in FIG. 1;

FIGS. 4 and 5 are similar views of a prior art lamp and base FIG. 6 is a fragmentary longitudinal sectional view of a molding die and a plunger die for manufacturing the base shown in FIGS. 1 to 3;

FIG. 7 is a plan view of the molding die, the circular contact portion of the eyelet being shown in phantom outline for illustrative purposes; and

FIGS. 8-9 and 10-11 are similar views of two alternative embodiments of molding and plunger die apparatus.

DISCRIPT ION OF THE PREFERRED EMBODIMENT In FIG. 1 there is shown a general lighting incandescent lamp 10 having a glass envelope 12 and a base member 14 that is attached to the sealed neck of the envelope by basing cement (not shown) in accordance with standard lamp-making practice.

The base 14 consists of a threaded metal shell. 15 of aluminum or the like that is terminated at its outer end by 'a domed portion 16 and an insulator 18 that is molded into the bottom of the shell. The insulator l8 is of generally frusto-conical configuration and composed of glass or other suitable vitreous or plastic material. In accordance with the present invention an eyelet 22 of suitable sheet metal, such as brass or the like, is embedded in the insulator 18 in a manner such that the plate-like contactor part of the eyelet is exposed and its peripheral edges are protectively recessed within the confines of the molded insulator. Small segments of the eyelet edges are left exposed by a series of indents such as three arcuate notches 20 that are formed in and circumferentially spaced around the outer rim of the insulator 18.

As shown more particularly in FIGS. 2 and 3, the notches 20 are equidistantly spaced around the circular rim of the end face of the insulator 18 and the circular contact portion of the eyelet 22 is located within a shallow depression 23 of circular configuration that is centrally located with respect to the circular end face of the insulator.

The circular depression 23 and spaced notches 20 provide three arcuate shoulders or ledges 19 of substantially uniform thickness and height that constitute the outer rim of the insulator 18, overlap the peripheral edges of the eyelet 22 and are substantially flush with the exposed peripheral surface portions of the eyelet. Thus, the peripheral end edges of the eyelet 22 are protectively recessed behind the contiguous ledges 19 and are incapable of becoming snagged or bent outwardly from the end face of the insulator 18 during subsequent bulk shipment or processing of the completed bases.

Even though small segments of the eyelet edges are exposed by the notches 20, the latter are so narrow and of such depth that the edge segments of the eyelet 22 can only be engaged by a sharply pointed tool or object that is inserted into the notches. The notches 20-are,

accordingly, of such configuration that the peripheral end edges of the embedded eyelet 22 are, for all practical purposes, completely recessed within the confines of the insulator 18.

As will be noted in FIG. 3, one of the lead wires 17 of the lamp is joined to the eyelet 22 by solder 24 or other suitable material which fills the eyelet aperture.

The improved base 14 provides an additional advantage in that it enables the eyelet 22 to be made of thinner sheet metal than heretofore since the eyelet is shielded and need not be as rigid. In the prior art bases the eyelet was made from sheet metal approximately 0.0085 inch thick to give the eyelet sufficient rigidity to resist being bent outwardly if inadvertently snagged while being handled or shipped in masse. Since this degree of rigidity is no longer required, the eyelet thickness has been reduced to about 0.007 inch and tests have indicated that this can be further reduced to 0.005 inch. However, in order to avoid mechanical deformation of the thinner eyelets before they are embedded in the insulator, the central portion 25 of the eyelet 22 is dished inwardly (see FIG. 3) to increase the rigidity of the enlarged contactor end of the eyelet. This dished segment is seated in a similarly shaped recess formed at the bottom of the depression 23 during the insulatormolding operation.

As will also be noted in FIG. 3, the eyelet 22 is located in the aperture of the insulator 18 and thus provides a passageway that extends from the outer surface of the contactor portion of the eyelet to the interior of the base shell and permits the lead wire 17 to be threaded through the base and solderedto the eyelet in the regular manner.

Another advantage afforded by the invention resides in the fact that. it permits the diameter of the circular contact portion of the eyelet 22 to be reduced without changing either the overall configuration or size of the insulator 18. This not only further reduces the amount of metal required to form the eyelets but permits conventional insulator-molding dies to be modified and used to manufacture the improved base.

As will be noted in FIGS. 4 and 5, a lamp 30 having a conventional base 32 employs a similarly shaped molded insulator 34 that is joined to the domed end 33 of the base shell but is devoid of notches and arcuate ledges. The embedded eyelet 36 is considerably larger in diameter, made of thicker material and its circular contactor portion is disposed on top of the flat end face of the insulator 34 and thus has its peripheral edges entirely exposed. The lead wire 38 is joined to the eyelet by a filling 40 of solder in the usual manner. In the case of medium screw-type bases of the type hereinshown, the modifications in insulator and eyelet construction effected by the present invention has permitted the eyelet diameter to be reduced from seven-sixteenths inch to three-eighths inch without encountering any problems as regards making a positive contact with sockets now in use.

METHOD AND APPARATUS In FIG. 6 there is shown a preferred apparatus 42 for manufacturing the base 14 shown in FIGS. 1 to 3. This apparatus consists of a molding die 44 that has an annular curved seat 45 at its mouth for nestingly receiving the domed end 16 of the base shell 15, and curved conical side walls 46 that merge with a flat bottom wall 47 that has acentrally located aperture 49. Three equidistantly spaced projections such as lugs 48 (shown more clearly in FIG. 7) are located at the bottom of the die 44 and extend radially from the side walls of the die toward the center of the die cavity. The lugs 48 are so shaped and dimensioned that they form a circular pocket which nestingly receives the circular contact portion of the eyelet 22 and centrally locates the eyelet at the bottom of the die cavity.

Since the circular bottom portion of the die 44 is of larger diameter than the eyelet 22, the peripheral end edges of the received eyelet are spaced a uniform distance S(see FIG. 7) inwardly from the surrounding side wall portions of the die. Thus, when a reciprocably movable plunger die 50 is advanced toward the bottom die 44 the conical shaped end 51 of the plunger die forces the charge of molten glass (or other hardenable insulation material) into the spaces between the peripheral edges of the eyelet 22 and the adjacent side walls of the die and forms an insulator 18 having arcuate ledges 19 that overlie the edges of the eyelet but are flush with its outer surface.

As. shown in FIG. 6, the plunger die 50 has a grooved flange portion 52 that engages the inturned collar of the domed end 16 of the base shell 15 and forms a seal therewith which prevents the molten glass from leaking into the interior of the base shell during the insulatormolding operation. The tapered tip of the plunger die 50 engages and is seated in the apertured neck portion of the eyelet 22.

As will be appreciated by those skilled in the art, three spaced axially extending pins can be used in place r v of the three radially extending lugs 48 in the bottom die 44 to form the circular eyeletreceiving pocket. in this case, axial grooves will be formed in the end face of the molded insulator and the eyelet would be almost entirely recessed. Apparatus 42a having a molding die 44a with three such pins 53 is shown in FIGS. 8 and 9. As illustrated, the pins 53 project in an axial direction into the mold cavity from the flat wall 47a of the die 44a and form a pocket for the eyelet 22a fed into the die. As will be noted in FIG. 9, the pins 53 are so positioned that the eyelet 22a is spaced a uniform distance S from the side walls of the die 44a.

Alternatively, centering the eyelet 22 in the bottom die 44 can be achieved by a single hollow pin or the like that engages the apertured neck portion of the eyelet and is attached to and extends upwardly from the bottom wall of the die. Apparatus 42b of this construction is shown in FIGS. 10 and l 1. As illustrated, the molding die 44b is provided with a single centrally located projection such as a hollow pin 54 that extends into the mold cavity from the bottom wall 47b of the die and engages the apertured neck portion of the eyelet 2212 that is fed into the die. The pointed end 51b of the plunger die 50b fits into the aperture 49b defined by the hollow pin 54 and the latter (as shown in FIG. 11) positions the eyelet 22b so that its peripheral edge is spaced a uniform distance S from the side walls of the die 44b as in the previous embodiments.

It will be appreciated from the foregoing that a novel apparatus has been provided for manufacturing bases that have molded insulators and integral protectively recessed end contacts. The bases can be efficiently and economically manufactured by making small but critical changes in the base manufacturing techniques and apparatus now in use.

While the invention has been illustrated and described in terms of an incandescent lamp and a medium-screw type base, it will be appreciated that the inventive concepts can also be used in the manufacture of other types of lamps and devices (high-pressure rrier-' cury vapor lamps, screw-in fuses, etc.) and other kinds of bases, such as mogul, bayonet, three-lite bases, etc,

I claim as my invention: 1. in a base-making machine wherein a body of hardenable insulating material is concurrently molded onto the bottom of a metal shell and around the necked portion of a metal eyelet to form an insulator which joinsv the members together and holds the eyelet in a position 6 such that its opposite end is exposed and serves as an end contactor, the combination comprising: I I

a die that (a) defines a mold cavity the eyeletaccommodating portion whereof is larger than the contactor end portion of said eyelet and (b) has an annular seat at its mouth that is contoured to nestingly receive the bottom portion of said metal shell, means'within said die for orienting an eyelet fed into the die so. that the contactor end portion of said eyelet is seated in the eyelet-accommodating portion of the die and its peripheral edges are spaced from the surrounding side walls of the die and said eyelet is also spaced from a metal shell disposed in the annular seat of said die, and means for compressing a charge of hardenable insulating material introduced into said die and forcing such material into contact with the bottom of said metal shell and into the space between the said surrounding side walls of the die .and the peripheral edges of the contactor end portion of an eyelet that is fed into said die and positioned therein by said orienting means. i 2. The appartus of claim 1 wherein; said eyelet-orienting means comprises a plurality of spaced projections that extend into the mold cavity from the walls of the die, and said means for compressing the charge of hardenable insulating material comprises a second die that is reciprocally movable. 3. The apparatus of claim 1 wherein; 7 said eyelet-orienting means comprises three spaced lugs that are located at the bottom of the die and extend radially inward from the surrounding side walls of the die toward the center of the mold cavity, and said lugs are of substantially the same width and height. 4. The apparatus of claim 1 wherein said eyeletorienting means comprises three spaced projections that extend axially into the mold cavity from the bottom wall of the die.

5. The apparatus of claim 1 wherein said eyeletorienting means comprises a single centrally located projection that extends axially into the mold cavity from the bottom wall of the die and is adapted to engage the apertured neck portion of an eyelet fed into said die.

Claims (5)

1. In a base-making machine wherein a body of hardenable insulating material is concurrently molded onto the bottom of a metal shell and around the necked portion of a metal eyelet to form an insulator which joins the members together and holds the eyelet in a position such that its opposite end is exposed and serves as an end contactor, the combination comprising: a die that (a) defines a mold cavity the eyelet-accommodating portion whereof is larger than the contactor end portion of said eyelet and (b) has an annular seat at its mouth that is contoured to nestingly receive the bottom portion of said metal shell, means within said die for orienting an eyelet fed into the die so that the contactor end portion of said eyelet is seated in the eyelet-accommodating portion of the die and its peripheral edges are spaced from the surrounding side walls of the die and said eyelet is also spaced from a metal shell disposed in the annular seat of said die, and means for compressing a charge of hardenable insulating material introduced into said die and forcing such material into contact with the bottom of said metal shell and into the space between the said surrounding side walls of the die and the peripheral edges of the contactor end portion of an eyelet that is fed into said die and positioned therein by said orienting means.

2. The appartus of claim 1 wherein; said eyelet-orienting means comprises a plurality of spaced projections that extend into the mold cavity from the walls of the die, and said means for compressing the charge of hardenable insulating material comprises a second die that is reciprocally movable.

3. The apparatus of claim 1 wherein; said eyelet-orienting means comprises three spaced lugs that are located at the bottom of the die and extend radially inward from the surrounding side walls of the die toward the center of the mold cavity, and said lugs are of substantially the same width and height.

4. The apparatus of claim 1 wherein said eyelet-orienting means comprises three spaced projections that extend axially into the mold cavity from the bottom wall of the die.

5. The apparatus of claim 1 wherein said eyelet-orienting means comprises a single centrally located projection that extends axially into the mold cavity from the bottom wall of the die and is adapted to engage the apertured neck portion of an eyelet fed into said die.

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