US2332478A - Method of making lamp sockets - Google Patents

Description

Oct. 19, 1943.

W. P. TOLBERT METHOD OF MAKING LAMP SOCKETS Filed April 27. 1942 levee /7 z Mrz 50 7 Z/illiavz fjalbert 2nd Frau;

Patented Got. 19 1943 1;'wmaaepgmbm, nor: Madison, idea, assignor I 1 to AnthcsFolOeOiler Company, Fort Madison,

. Iowa, a corporation of Iowa 3 The present invention relates"to thefnianufack ture of lamp sockets and is particularly directed to an improved processof making that type' of lamp socket which is comm-only used: infhead I lights and tail lights and similar installations; in

trucks and automobiles. Theseflamp" sockets comprise a cup-shaped element having a reduced extension at the bottom ofithe cup, whijch exten"- sion is open at its end and is used a a means of mounting the cup, The extension,forexam ple;'maybe passed thr-oughan aperture in a-su'pe por'ting structure and bent over and outwardly to clamp th'e cup in placeH-The electrical leads for-the lamp "pass out through theopening in the extension; The lamp unit itself is supp orted in the socket by means of bayonet'slots oppositely disposed in the'sock'etand' pins onthe lamp unit; Lamp sockets or this character ar -now drawn from metal and are quite satisfactory rom-nit standpoint of operation. i I V The purpos of my inventiorris tolprovide a method of makinga lamp socket' which is fully satisfactory. for the same purpose buhwhijcl; is produced at a 'substantial'saving'in time and is reduced y as much as one-ham we material so that the ultimate cost of the socket In the -manufa'cture of the "drawn socket the operations are generallyas*fo1-lows:- a' disdof meta-1'15 blanked out of-th'e metal Sheet ahd'in' just described does not lend itself to a progressive Th reduced extension is.

operation. However, my method is of suchnature that continuous progressive-operation is the best way in which to make the socket.

Specifically it is the purpose of the present invention to provide a method of making a lamp socket wherein a strip of metal is embossed, pierced and burred, drawn and formed into a complete socket with a minimum amount of waste material and a minimum number of operations. I utilize the formation of-the bayonet slots as a part of the preparation of the blank for drawing and forming so that the material which has to be taken out to form the bayonet slots is removed before there is a cup. I avoid any operations on the cup and. thus prevent any Applicati n'Apr'iIZ'Z,1942,;SeriaiNo. 440,525-

t atime,g rmane weakening or distortion-of thefjformed I make the size and shafpqoi the removed piec such as'to produce the'proper dimensionsoffthe blank with I respect :to the piinchaiidi dieto "obtain the optimum strength in the completed socket shell, aswellasto produce a bayonet'slot.

" f 'fI'he features and advanta s' 'of the invention will appearmore-fully asthe drawing wherein the -'pref erred steps of; the method are illustrated diagrammatically andf the iiltimate'ro'rm dfthe' finished articleiis shown iis e und a wer nape dar n and descriptiongare illustrative 'only andarefnot to be taken as limiting the invention exoe' r Fig. i ms-som w t b 'e t v in the final drawing and forming operation which produces the cup s'haped socket;

elements also indicated; i -l?ig.-'3' is a View inside elevation of the completed socket showing howit receiiIes-a standard lamp; and r I Fig. 4' as. sectional 'view me substantially on the line 4-4 cr rig. 3 with thelan'ip rembved; Referring no'win detailt' the drjawing', Fig. 1

shows in plan" a strip of metal thatihas'pro gressed far enough to ha'vehad performed there'- on all of the operationsfexcepting-the severing ahd d-rawihg anei rorming o erations The initial station in the production of' the-' -1am socket is shownat the right in Fig. -1.-"'-1 "1;1s'is th station where the material is embossed slight s moicated at 40 as amnion step in form'iiigth a duced extension ofthe ultimate cup-shaped socket. This operation is performed at the entering end of a strip of metal 9 which is the proper width to form a socket of the ultimate desired length. At the next station in-a progressive operation the embossed portion I of the strip is increased in height. At the third station the embossed part In is pierced at H with a small opening, and the size of the opening II is such as to prevent the metal, when it is forcedoutwardly at the reduced extension, from splitting.

The strip is then fed forward to the fourth station where it is pierced to provide an opening I2. 7 The material removed to form the openings H and 12 constitutes the material wasted for scr mi nzpwceeds', reference'beinghad; to'the accompa yin i im is anzview illustrating';the progressive stages throughwhich a strip or mat rial go s 7 up t the point where down-'everthe blank'and "punch Y is s a {sectional view taken substantially on the line 2--2 or Fig; 1,with;punch and {die} each completed tube. It is necessary to form the opening l2 in order to form the bayonet slots, as will appear more fully hereinafter. At the fourth station the burring operation, by which a reduced extension I3 is formed from the embossed part I 0, takes place.

In the fifth and final stage in the progressive operation a punch I4 is centered directly beneath the reduced extension [3 by a projection Ha that fits in the extension IS. 'The end of the strip is cut off along the lines I5 and I6 and the metal is drawn over the punch M by a die I1 and the ends of the cut ofi blank are formed into semi-cylindrical shape about the punch. Upon the opening movement of the press the finished article is discharged. i

It will be seen from the foregoing description that a completed socket is formed for each operation of the press. A strip of metal is fed into one end of the press and the sockets are discharged at the other end. s

. Lhave' discovered a definite relation which mustbe maintained between the width of the piece and the socket diameter in order to obtain theoptimum strength and shape of the final cup. It will be noted from aninspection of the completed cup and an inspection of Fig. 1 that a certain portion of the metal (indicated at IS in Fig. l by a dot and dashcircular outline), substantially at the center of the piece, is drawn down over the. .punch to form-acompletely closed cup at ,the basenof the socket.- This width of metal which drawn down over the punch acts to impart suificient rigidity to the socket walls to preventthelnatural' recovery of the metal from spreading the open end-of the socket enough'to cause the socket to hold the lamp insecurely.

Itmust not be of an amount sufficient to cause the metal to crowd or thicken up in the drawing operation because then the natural tendency of the crowded metal to expand when released from the-die wouldincrease the bell-, or recovery and furthermore weaken the structural strength of the cup. The piece for a standard size socket having a diameter of .640 inch should be .813 inch wide or approximately 1.27 times the socket diameter (the socket diameter being taken from center of metal to center of metal). In other words, the socket diameter is substantially fourfifths of the width of the cutoff piece at the center line of the strip. 1 g i The socket-iormedv by my method does bell or increase-. in size somewhat toward the open end. This permits a lamp to be inserted'more easily and permits alimited'amount of movement that tends to prevent the lodging and accumulation of corrosion products, dirt, etc. Electrical contactthrough the pins on the lamp and the hook portions of the bayonet slots is equally satisfactory with that in the drawn sockets.

It will be noted that the enlarged portion of each bayonet slot extends all the way up to the drawn part of the socket. This wide opening makes the positioning of the lamp to seat in the notches of the bayonet slot less critical. When the lamp is inserted far enough that the pins clear the points of the bayonet slots any further insertion makes no difference. The lamp can be turned even though it is pushed in way beyond normal position.

The notch or hook portions of the bayonet slots are spaced properly because the pilot projection Ila exactly centers the piece. Even a slight variation the positioning of the notches does not prevent the lugs on the lamp from engaging in the notches because the slight bell of the cup permits adjustment of the lamp under the spring pressure thatholds it in place.

From the foregoing description it is believed that the nature of the present invention and the best mode of carrying it out will be clear to those skilled in this art.

Having. thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A'method of making a lamp socket, comprising taking a strip of metal and deforming and cutting it in progressive steps by drawing a relatively small tubular sleeve, then cutting out long narrow transverse pieces of the metal between the side edges of the strip and at a fixed distance from the small sleeve and cutting the strip transversely from the ends of the opening left by the cut out piece, and drawing and forming the generally rectangular piece thus cut off into a-tubular socket wherein the cut edges along the sides of the piece define oppositely disposed bayonet slots, and an annular portion of the piece centered about said tubular sleeve is drawn into cylindrical shape.

2. A method of making a lamp socket, comprising taking a strip of metal and deforming and cutting it in progressive steps by drawing a relatively small tubular sleeve, then cutting out long narrow transverse pieces of the metal between the side edges of thestrip and at a fixed distance from the small sleeve and cutting the strip transversely from the ends of the opening left by the out out piece, and drawing and forming the generally rectangular piece thus cut ofi into a tubular socket of a diameter equal to substantially four-fifths of the width of the piece wherein the cut edges along the sides of the piece define oppositely disposed bayonet slots, and an annular portion of the piece centered about said tubular sleeve is drawn into cylindrical shape.

WILLIAM P. TOLBERT.

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