US2646554A - Lamp socket - Google Patents

Description

July 21, 1953 s. w. ol-LOCK LAMP SOCKET- Filed Oct. .6, 1951 INVENTCR. S. %60/V P044005.

Y 44: WW //%%4 ATTORNEYS I Patented July 21, 1953 7 LAMP soo n'r V S. Wilson Pollock, Gamp'Hill, Pa., assignor to Aircraft-Marine Products Inc., Harrisburg, Pa., a corporation of New Jersey Application October 6, 1951, Serial N 0. 250,077

This invention relates to a lamp socket particularly intended for miniature lamps, such as Christmas tree lamps, although it can be readily adapted to and used for full size lamps and bulbs. Lamp sockets in this category in the past have not been altogether satisfactory and particularly 1 Claim. (Cl. 339-97.)

they have been unduly expensive to manufacture,

considering their relatively limited use. Lamp sockets for miniature lamps, as well as for larger size lamps, must be of durable construction and of course must be so manufactured and assembled as to be safe from the standpoint of the socket providing good electrical connections in which short circuits are not apt to easily occur. Poor electrical connections and short circuits may be both annoying and dangerous. Particularly in connection with Christmas tree lights, defective sockets may be the cause of serious and destruction fires. It follows, accordingly, that such electrical contacting members must not only make good contact to assure reliable lighting but must be securely held so as to assure that it will not give rise to short circuits or accidental contacts.

The primary object of the invention is to meet the demand for a very inexpensive yet reliable lamp socket in a novel way calculated to overcome the deficiencies of heretofore known sockets of this type. Another object is to provide an extremely simple and inexpensive lamp socket made of a single piece of metal by mass production methods. Another object is to provide an improved and simple way of connecting electrical conductors to the lamp by means of a socket formed as described. Another object is to provide a lamp socket utilizing simple but yet novel arrangements for providing the electrical contact with the bulb and connecting it with the electrical conductors to the socket. Further objectives and numerous advantages of the invention will become apparent from the following detailed descriptions and annexeddrawings'wherem:

Figure 1 is a perspective phantom view of a preferred form of the invention as applied in a lighting circuit.

Figure 2 is a longitudinal axial section on Figure l, but with the lamp positioned the socket. f

Figure '3 is a cross sectional view taken along the line 3.3 of Figure '1,'but before crimping of the ferrule. 1

Figure 4 is a plan view of the ferrule of Figures 1 and 2.

Figure 5 is a plan view of a modified form of ferrule for the electrical conductors.

I central conductor forms a contact for engage standing sides 24.

Figure 6 is a longitudinal section taken on "the axes'of the wires and socket of Figure l,'but with a modified end contact.

Figure 7 is a view in longitudinal axialsec'tion of a partially formed blank for a modified embodiment of the invention.

Figure 8 is a sectional view taken along line- 8-8 of Figure '7.

Figure 9 is a cross-sectional view showing a ferrule embodying the invention being crimped in curling dies.

Referring now to Figure l of the drawings, the socket for the miniature lamp is indicated at H) and a miniature lamp is shown at I2. The lamp has the usual screw threaded base and the socketis dimpled as shown at 14, whereby the screw thread of the lamp base can be engaged when screwed into the socket. The socket may, of course, be of the bayonet or other types with appropriate changes well understood in the art. The. socket is preferably made by rolling a strip of metal, e. g., brass, into a circular cylindrical form and the edges may meet in a butt seam I6 with or without brazing or may be interlocked in known manner.

As pointed out in the foregoing, the socket is made from a single piece of metal and it has an. integral extension comprised in this example of a tab 18, extending from the side opposite the seam Hi, to which is integrally attached a chan nel-shaped ferrule-forming portion 20. This channel comprises a base portion 22 and up- Upstanding from a central area of the base portion are prongs 26, struckup from the base portion 22.

Figure 1 shows the wires of the lighting circuit in place in the ferrule portion 20, ready for crimping to secure and locate them. Disposed in the bottom of the channel member 20 is an insulated wire 30 which is impaled by the prongs 26, so that they pierce the insulation and engage between the strands of its multi-strand copper conductor. A second insulated wire 32 is positioned over the insulated wire 30 in the channel member 20. Wire 32 is stripped for a short distance at its end so that the exposed end of its ment with the center contact of the lamp base. As set forth below, the end contact may be formed by soldering or brazing the exposed ends of the wire strands or by pushing into the end of the stranded wire a contact member 46 like a nail or escutcheon pin and compressing it with the wire by crimping of ferrule 20.

Figure 3 is a sectional view showing the shape of the ferrule member 2|] before it is crimped and the disposition of the wires within it. As may be seen, the prongs 2B pierce the insulation of wire 30 when it is forced down by the crimping operation and thus extend between the strands of the multistrand conductor therewithin to form electricalcontact therewith so that this wire is well connected electrically to the socket forming the female connection to the lamp l2. .The upper ends of the sidewalls 24 of the ferruleforming channel member extend like cars from the base 22 and are forged down over the top of the upper wire 32 by the crimping so that a secure ferrule is formed around the two wires holding them in place and maintaining pressure contact against prongs 26.

The crimping is performed in known manner by crimping dies, the female of which corresponds in form to the top and sides of the ferrule as shown in Figure 1 and the male of which corresponds to the bottom of the ferrule. The wires are placed in the open channel which is placed over the male die and the dies are then brought together, the edges 25 scraping the faces of the female die to gather the wire, and being bent over by the die faces. The wiping action of the die faces plus the final compression produces a cold forging of the ferrule to the permanent form shown in Figure 1. This crimping pressure also presses the two wires together and forces prongs 26 into the lower wire 30.

t Figure 5 shows a slightly modified form of U- shaped channel member wherein the upper edges of the sidewalls have a sinuous formation as in-v dicated at 38a, so that when they are bent inwardly, or crimped, they come together in the manner shown in Figure 5. This assists in gathering in the wire and pressing it down without pinching it in the seam 38.

Figure 2 shows an electrical conductor 12, the end portion 44 of which has the insulation stripped to expose a short length of the conductor strand for a contact at the end. This end is dipped in solder or braze 46 so that the strands at the end'of the wire form a compact contact button which engages the contact at the base of the lamp. In Figure 6, a contact member 46a in form similar to an escutcheon pin, is inserted into the end of the wire, and the wire compressed against it by the crimping.

Figures 7 and 8 show another embodiment of the invention wherein the receptacle and the ferrule are formed of one piece and the electrical conductors are clamped and attached thereto. The socket is indicated at [D and in this case is formed by deep drawing a cup and rolling the spiral thread or groove in its sides so that the lamp can be screwed therein. The socket has an integral ferrule-forming portion 20?) joined to the socket by the part I812, which as shown is an unsevered part of the bottom of the drawn cup I019. The ferrule 20b is a portion partially severed and bent to form the ferrule and to grip the wire therein. As shown in Figure 8, this embodiment illustrates another feature of invention, i. e., the same ferrule is crimped onto both wires, the end of wire 302) being stripped and lying bare against the ferrule by which it is connected to the lamp socket, and the other wire 32b re- In Figure 9 is shown in cross section the ferrule portion 26c of another embodiment of the invention assembled with two wires c, 32c and the assembly in a crimping die set 60, 62. The ferrule portion in this case has side portions 240 which when the dies are closed are guided along the concave surfaces 63, 64 the one to be curled back on a short radius so as to penetrate the insulation nearly radially and thus contact and clamp the central conductor. edge may be toothed as shown at 65 and the other side 240 is curled back on a radius only slightly less than that of the wire whereby to grip the wire without penetrating its insulation maining insulated within the ferrule. 2% but I having a contact projecting as the center contact.

. Wherea one wire system is to be used with the receptacle grounded to a frame, the wire 3% may be omitted without other change.

and to hold it approximately coaxial with the receptacle. In the final compression between the dies, the ferrule portion is forged onto the wire with circumferential compression of the ferrule wall.

From the foregoing, those skilled in the art will observe that I'have provided a novel construction and arrangement whereby the lamp socket and the connection thereto can be simply and inexpensively made. The socket is made from a single piece of metal which may be stamped out in the proper form and then the appropriate portions bent to form the U channels which are then crimped around the wires in accordance with a known crimping process. These latter portions do not seriously increase the width of the stock required but fit economically into the receptacle blanks. Although the formation of the socket is extremely simple, effective'and inexpensive, it is nevertheless very serviceable and durable, providing secure electrical contacts not readily susceptible of short circuits.

In this specification and the accompanying drawings, although I have shown and described 1 several perferred embodiments of my invention and various application thereof, these are intended to be illustrative in order that those skilled in the art may fully understand the invention and principles thereof, and the manner of applying it in practical use so that they may modify and adapt it in various forms, each best suited to the conditions of a particular application.

I claim:

A lamp socket comprising a generally cylindrical metal receptacle adapted. to receive the base of a lamp bulb therein, said member having extending therefrom a ferrule member connected at its bottom portion to the receptacle thereof, an insulated wire engaged in the ferrule, said ferrule member having at least one inwardly directed prong piercing the insulation and making electrical contact with the wire, a second insulated wire clamped beside said first wire in the ferrule and having a central conductor exposed at its end near the axis of said cylindrical member but with the insulation of the wire insulating said conductor from the ferrule.

S. WILSON POLLOCK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,671,226 Caruso May 29, 1928 1,731,205 Scofield Oct. 8, 1929 1,899,254 Bear Feb. 28, 1933 1,970,767 Rabezzana Aug. 21, 1934 2,163,771 Alden June 27, 1939 To this end the-

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