US2576437A - Electric contacts - Google Patents

Description

Nov. 27, 1951 J. F. BARRY 2,576,437

ELECTRIC CONTACTS Filed May 10, 1946 5 Sheets-Sheet 1 FIG. FIG. 2

PUNCl-IES JO 8 3/ ARE OPE/M TED SIMUL TAIVEOUSLY F IG. 3 FIG. 4 /2 6 INVENTOR By J. l-. BARR) A TTORNE V NOV. 27, R B Y ELECTRIC CONTACTS 5 Sheets-Sheet 2 Filed May 10, 1946 INVENTOA J E BARR) ATTORNEY Nov. 27, 1951 J. F. BARRY ELECTRIC CONTACTS s Sheets- Sheet 3 Filed May 10, 1946 lNVENTOR J F. BARR) A TTORNEV Patented Nov. 27, 1951 UNITED STAT E S PAT E NT OF F'IC'E 2,576,437. ELEQTRIC CONTACTS Joseph F. Barry, Snmmit, N. J., assignor to Bell Telephone Laboratories, Incorporated, New

York, N. Y., a corporation of New York Application May- 10, 1946, Serial No. 668,965

2. Claims. (01. 7;8 ,-.v1'Z-) This invention relates to electric contacts and ample,v thesprings carryin h fiil p lg R m.- particularly to extruded contacts. adapted for have been madeadjustable in the twogtransrerst use in mounting a quartz or other piezoelectric directions in order to adjust the pl S liQn and. crystal body, or for use as electrical contact elealign the, clampi pi s. pposit y; t e fina n en rally. 5 clampin pins have been. stak i and: o de iia n One. of the objects of this invention is to in-. ODD Y aligned, holes hi str s; sure. a predetermined alignment or arrangement other arrangements; have been resorted .9 with forcontact elements. the object; of-prQ-vidiIJ-s. easily, quickly andlcheap- Another object of this invention is to provide 3 a P Of C p g cOmla tst that, mi ht be aligned contact elements formed from the con- & relied: upon in. mass; pr duct o o obtain pretact supporting material itself. ci ly opp si e. c ntacts at; l. ime

Another object of this invention is to provide In ac or anc with. his. nt ntion he e fiqri oppositely extruded clamping pins suitable for troded cry tal; b d ay bf; mounted QT VZQQQ mounting a piezoelectric crystal body. a pa r Of extruded QIlJQQGt; poi t Pi s. (@01 Another object of this invention is to provide Xa. :t1I/; 01"- prec ely a gn d; w th. GSPECIE. a fixed reference axis, as with respect to, the each other andcw iqh mar it: QDL PQTS Q 0 amt base of the crystal holder, for not only. locating suitable C ds-fl wi g m allic conductive inathe. axis of the extruded contact elements but teria So enou h .9 b mbfid fidl under: spring also for allowing crystal elements of different. pressure, in,thesmall irregularities occurring-in;

square face dimensions to be readily, centered 20 the. surface. Q i thfl e trodes: G XSIM 913. 1% '39: about the same fixed axis. referred to, when. the. btain the desired; it l li ll XflQi'z. O pre ise;

crystal element is assembled between the ex: alignment the pail 0f z ll i i lqqi l fi 2 39 truded' contact. elements by means of a suitable. pair o o tact P011 135 ma b9.- s m tan u ly fixture. extruded into the same cavity of a u tab di Another object of this invention is to. provide onecontact point being extruded from eac "do an impro ed pressure type crystal mou ting suito the. die, whereby an exact or ccurate lta a l for mass prod cti n. n having o d. me.- ment of the pair of Contact n s; s insu. 31 chanicaly and electrical performance. with none. but rough tolerance necessary.- in the For; mounti a d stablish g le trical conov t al ,fabri ation o the mQuIt 2. 8 he nections, with quartzand other piezoelectric tes po nt a e e trud as t l st or cr tal. l m n s it. i o ten ad ant ous to te n the fabr ca ion thereo ass r n tr empl y ne o mor pairs of: pposi ely iSPQsed closes srs ss n he Par s O the 1 9 2- a clampin n i t or pins, between which the elecnot n. h man fas re i. 21 i? 132 trod-ed crystal element may be firmly and resince the end requirement of contact point a an;

siliently clamped under sufiicient pressure, ape merit met automatically by, proper design; of plied. ya. sui able s r or mix f spr ngs, t he ie- Mil- 3 936 3 un form t produ t ay ere tn bo i m vemen r dis ac men oi the be Q s ieedri ass pr dusti t sin ex crystal element out of its clamped; positi n is not necessary by the operator in order to obs.

In. such, r s e type cry ta ampme arta l; s dmss is n e s r s s abil t an rangements, it is desirable that the aligned l .gQQQ ea i i fi fi' e st ce 1 5 0 Q, for the cl mping. n a t in or m nts b ispose ese qtt fi t bq yn. advan age o spscialexactlyr pr cis y pp s each. other o su int s tha t f? a men s, 6 i s; the

reaso a o reduce distorti nal. tr i n he s a san iZQ Qfi he c ntact pin 1; mints es cr sta elem nt ts s a esu t if smal bend: be q ain directly i; mlg dssisn' i the-dis. ins; mome ts t at. y b cc si ned y ne 4:; teth r han. ut a s sett emen of ti e: ali ned clamp n o tact samba. to. ermit ery 12 t Dim the sr s slmou t be O t in a ma l a pin a as. to. e used; here i s. P lssal snmsn 0.1- he co t m nts de to csntsst a sme l r s le e t Qnl-re ruded Qlamp es 19in thi of, pre sureat or. as n ar s s bl t e ode t le et assumin owe sass d ith 11 and for other reasons. is suitable for continuous line assembly n ur r; r s t e mou t rr ngements, maeutas ure wi a m imum at waste n ro- 3 var es. means have e resorted o h q ssins- Shou d c m let d r s s uni ai in order to align; or adjust the relative; positions because 0; a defective. crystal, the. crystal may Q t. new f imi q ct p s n Qm s e s e r sci'and h 2 Qun e f Q' sr fi 't izqsieene w th re pect 9 sash o h r- F r- 5-- it a earitu a re u t. s defect ve. the QKSISJJQL may be salvaged and used again without reprocessing. The assembled unit has good mechanical and electrical properties, and is free from such electrical troubles as cavity resohances.

While this invention is described particularly in connection with a method of securing the precise alignment of contact points for holding a crystal body with reference to the center line of the contact points, it may be applied to contact points for mounting other types of vibrating systems, and to contact points generally where a precise alignment or arrangement of contact members is desired to be obtained, especially where large scale production is concerned.

For a clearer understanding of the nature of this invention and the additional advantages,

features and objects thereof, reference is made to the following description taken in connection with the accompanying drawing, in which like reference characters represent like or similar parts and in which:

Fig. 1 is an edge view of a crystal unit provided with extruded metal contact pins between which the crystal body is clamped;

Fig. 1a is a perspective view of an electroded crystal element provided with a centering washer on each major face thereof;

- Fig. 2 is an enlarged sectional view of the extruded metal contact members shown in Fig. 1, and of a punch and die section which may be utilized to extrude such contact members;

Figs. 3 and 4 are enlarged sectional views, 11- lustrating alternative forms of cavity arrangements for the die section shown in Fig. 2;

Fig. 5 is an edge view of a crystal unit which is similar to'that shown in Fig. 1 but which is provided with crystal clamping contact members extruded directlyfrom the mounting springs, instead of from metal plugs inserted therein as illustrated in Fig. 1;

Fig. 6 is an enlarged sectional view of the extruded metal contact members shown in Fig, 5;

Figs. 7 and 8 are perspective and side views, respectively, of the mount as shown in edge view in Figs. 1 and 5;

-Figs. 9 and 10 are perspective exploded or disassembled views of a die and punch arrangement which may be used with the mount shown in Fig. '7 to form extruded metal contacts thereon;

Fig. 11 is a perspective view of the component parts shown in Figs. 7, 9 and 10 assembled for use; and

Fig. 12 is an enlarged sectional view similar to Fig. 2 but showing two pairs of insulated extruded metal contact 'members provided on a single pair of springs.

Referring to the drawing, Fig. 1 is a somewhat enlarged edge view of a pressure type crystal unit provided with oppositely extruded metal contact pins 8 and 9 adapted for holding and establishpunching and forming operation, after which they may be staked and welded or otherwise securely connected to the respective terminal pins 4 and 5 in order to obtain a good electrical connection therewith. The springs 2 and 3 and the pins 4 and 5, when so combined, may be rigidly molded into the supporting base I. The base I may be provided with any suitable enclosing cover 6 to form a sealed or evacuated enclosing container for the crystal unit. The base I, the springs 2 and 3, the terminal pins 4 and 5 and the cover 6 may be provided in other forms. The container base I and cover 6 may comprise a sealed molded type plastic container, or a sealed metal container 'which may be provided with suitable means for insulating the springs 2 and 3 from each other.

'After molding the fixed ends of the cantilever springs 2 and 3 and the respective terminal pins 4 and 5 into the phenolic or other suitable base I. the top portion or free ends of each of the cantilever springs 2 and 3 may be provided with pressure type extruded metal contact points or pins 8 and 9 of small diameter, such as of the order of .010 inch diameter, which may be used to clamp therebetween, under pressure from the springs 2 and 3, a quartz or other suitable piezoelectric crystal element IS. The crystal plate Ill may be provided with suitable opposite conductive electrodes ll and I2 as illustrated in Figs. '1 and 1a. The pressure with which the electroded crystal body I0 is held between the extremities or tips of the clamping pins 8 and 9 may be predetermined by the springs 2 and 3, dependent upon their composition, spacing, thickness, and length or height between the supporting base I and the longitudinal axis YY of the pair of clamping pins 8 and 9.

The crystal element Ill may be, for example, a CT or DT cut quartz crystal plate operated in the face shear mode of motion as disclosed, for example, in United States Patent 2,268,365 issued December 30, 1941, to G. W. Willard. Such face shear mode crystal elements Ii) have a node I6 or point of minimum motion adjacent the center of the major faces of the crystal plate I0, and the electroded crystal body Ill may be there nodally mounted and electrically connected by means of the extruded clamping pins 8 and 9. Where the crystal element I0 is a face shear mode quartz crystal element as particularly illustrated in Figs. 1 and la, the thickness thereof may be made of the order of .02 inch or other suitable thickness value, and the major face edges thereof may each be made of 0.1 inch and upwards according to the value of the desired frequency, the frequency, in the case of such a face shear mode crystal plate I0, being determined mainly by the values of the length and width edge dimensions of the square or nearly square major faces of the crystal plate I0.

While a particular type of crystal element I0 has been illustrated in th drawing, it will be understood that the invention may be utilized for nodally mounting other forms of crystal elements such as those operated in longitudinal or otherother conductive material such as films of silver,

ass-6,43%-

gold, aluminum or other conductive material. deposited by evaporation in vacuum, spray painting or byother suitable process. directly onto the opposite major faces of the crystal element I0. Where the. electrodes I I and I2 are, composed of baked silver paste coatings, the coatin ma terial I 1 and I2 may be. conveniently applied by spraying a solution of the silver paste in. liquid form onto the faces of the crystal. plate I0, and thereafter baking the sprayed silver-material. onto the crystal plate I at a suitable elevated temper-. ature. After such baking, the silver coatings II. and I2 maybe burnished. The process is adaptr able to a continuous belt spraying and baking operation for mass production purposes, and results coatings II and I2. of good mechanical properties. If desired, small silver washers. Il may be sweated by soldering to. the baked silver paste coatings I I and E2 on each major face ofthe crystal element I 0 in the nodal region I6 thereof to provide retaining seats: for nodally positioning the extreme tips of the clamping pins 8 and 9 therein. Such silver washers I1! are illustrated in Fig. la.

As; illustrated in Figs. 1 and 2, the crystal holder-may comprise thetwo springs. 2 and 3 having extrudable metal plugs or inserts I4 and. I5. therein at "I from which the fine contact points 8 and 9 are extruded for holding the electroded crystal element I0 therebetween, the extruding operation being done after the Springs; 2 and Q are assembled in the Supporting base. I, so that when the contact points 8 and 9- are extruded from the oppositely disposed metal inserts. I4 and 05 of the springs 2 and 3 into. a suitable die having a single cavity of the correct shape, length and diameter, the extruded contactpoints 8 and 9 are in exact or precise alignment with re: spect to each other. With this. type of assembly the electroded crystal plate I0 may be inserted between the tips of the spring-operated contact points 8 and 9 by means of any suitable spreader (not shown) adapted for spreading the springs 2 and 3 apart sufiicien-tly to permit inserting the crystal element I0 between the tips of the con-. tact points 8 and 9 at the nodal region I6 of the crystal element I0. When the crystal plate I0 is properlycentered, releasing the spreader referred to allows the springs 2 and 3 to exert their own clamping pressure on the crystal element I0 in order to hold it tightly in position between the tips of the clamping pins Band 9. The. crystal plate I0 maybe centered at the nodal region I6. thereofby any convenient means such as byv a washer IT, or by using an indexing tool which may, it desired, be coordinated with the die. tool 20 used for extruding the contact points 8 and 9. Suitable holding tools may be used in the subsee. quent adjustment of the frequency of the crystal plate I0 so that it need not be removed from its clamped position between the contact points 8 ands.

The stifiness of the cantilever springs 2 and 3 is important and may be made of a value to exert a suitable pressure such as of the order of one to two pounds load on the crystal body I0 disposed between the clamping pins-B and. '9. For this purpose the separation between the extreme tips of the clamping pins. 8, and 9; may be made of; a value from .001 inch to 0 inch before insertion of the crystal element. I 0. therebetween, or of other suitable value to. permit firmly holding the crystal element. I0. to be clampedbetween the tips of; the clamping pins; ii and 9.

Where it is. desired; to. conserve the. use oi Rhosphor bronze. material, the, springs 2 and 3 maybe made of clock sprin steel, forexample, and l brassv plugsor other cold-flowing metal inser 4; and is maybe staked in posit onin suitable openings, in the springs. 2 and 3. in the region 7. 13%. longitudinal axis. Y?Y' along which the clamping; pins 8 and 9.. are to be extruded from the metal comprising the inserts i4 and. i5, 111.6. springs; and .3, when composed of steel, may bev plated with zinc orother suitable plating material to reduce corrosion. If zinc plating is so used, an alcohol, and water wash may be afterwards. used. to re. move the excess plating salts from the zinc; plated springs. 2 and 3,.

The springs 2 and 3 may be made of equalifiiz e, shape and thickness, or one of the sprin s; 2 and, 3 may be made substantially thicker or heavier than the. other as illustrated by the springs 2 and; 3 in Fig. 2, thus in effect permitting one. Qf. the springs 3 to bend less than the other spring in order to. minimize the effects of Weaving ofthe springs 2 and. 3 which might tend tobring they 00-... axial clamping pins 8 and 9 out of alignment, If the heavier spring 2 is so used, it may be made. from .04 inch thick sheet metal stock, and the lighter one from .02 inch stock for example, The heavier-spring 2 may, if desired, serve as. an indexguide for the punch and die tools; 20, 30 and 3|, used for embossing and extruding the, clamping: pins 8 and 9, and also it may serve. as a guide. for the tool used for inserting and centering the. eleca. troded crystal element In in place between. the. tips of the extruded pins 8 and 9.

As illustrated in Figs. 1 and 2, the. metal plugs or inserts Hand I5 may each be constructed from a short section of C01dr11831d brasswire, or from other suitable cold-flowing material, of the order of 3 inch diameter or other suitable size, formed into metal plugs I4 and I5 each having a hollow cavity I8 in one side thereof. The. brass inserts I4 and I5, may be inserted in closeefitting circular holes provided at 'I' in each of the springs 2 and 3 and may be spun over to secure the metal inserts I4 and I5 firmly to the. respective springs 2 and 3. as illustrated in Fig. 2; oras illustrated in Fig. 12 when it is desired to 111511? late the metal plugs I4 and I5. from the springs 2 and 3. The. contact points 8 andu9 are ex: trudedfrom the brass inserts I4 and I5. by means of any suitable punch members 30. and 3| i'I'l-r sertable in the oppositely disposed cavities. l8 of the brassv plugs i4 and I5, as illustrated-in Fig. 2. The punch may comprise any suitable pair of coaligned punch members 30 and 3| adapted to cold press and extrude metal simule taneously from the brass plugs I4 and I5 into the opposite end openings of the cavity- 2| in the die 20, for forming the coaxially-aligned clamping contacts 8 and 9. carried b the pair of springs 2 and 3. The pressure to be applied inwardly to. the punch members 30 and 3| may be ofthe order of 2,000 pounds or of other pressure value suitable for extruding part of the. metal from the plugs l4 and I5 into the opposite. end openings of the cavity 2| in the die 20, as illustrated in Fig. 2..

Fig.2 illustrates an enlarged sectional view of a small section of the die 20 which may be used for extrudin thereinto the clamping pins 8 and 9 from the metal inserts I4 and I5, as illustrated in Figs. 1 and 2, or directly from the metal springs 2 and 3 as illustrated in Fig. 5. As particularly shown in Fig. 2-, the die 20 is used for extruding metal from the metal inserts I4 and I5 oi; Figs 1 and 2 The extruding punch mem- v bers 30 and 3| are operated inwardly, as'indie ca'ted by the arrows in Fig. 2. 'As illustrated in Fig. 2; the die 20 may be provided with a single cavity 2| of nearly uniformly tapered'diameter alongits length, the end openings. at the two pposite sides of the cavity 2| bein of slightly 8 larger circular area than that at the center region within the cavity 2|.

The die 20 may be provided with a cavity 2| of any suitable shape having end openings at the opposite sides thereof, the cavity 2] in the die 20being made of a size and shape correponding to the size and shape desired for the extruded contact members 8 and 9 mm formed therein; and the die 20 being located between the pair of springs 2 and 3 with the opposite end openings'of the die 20 disposed adjacent the opposite metallic portions I4 and of the springs 2 and 3 that are to be extruded into the opposite end openings in the die 20. area of the extreme tips of the clamping pins 8 and 9 is more or less critical since the reactanceresistance ratio Q of the crystal element In at resonance is a function of the area of contact therewith by the tips of the pins 8 and 9 and of the force exerted by the springs 2 and 3. The end portions of the pins 8 and 9 may be made to have a slight draft as illustrated in Fig. 2 in order to facilitate their removal from the ends of the opening'2l in the die 2|]. The shape of the cross-sectional area of the pins 8 and 9 back from the extreme tips thereof to the springs 2 and 3 is not highly critical, and may increase more or less gradually in cross-sectional area, and the shape of the cavity of the die may be made to conform thereto as illustrated by the die cavity 22 in Fig. 2and by the die cavity in Fig. 3.

Fig. 3 is an enlarged view in cross-section of the die section 20, showing an alternative form that may be used for the shape of the cavity of the die 20. As illustrated in Fig. 3; the die 28 may have a single cavity 22 of substantially enlarged diameter at the two opposite end openings' thereof which are disposed adjacent the metallic portions, comprising the plugs l4 and 15 or the springs 2 and 3, that are to be extruded into the end openings of the cavity 22 in the die 28 by means of any suitable punch members 30 and 3!. The oppositely disposed punchmembers 30 and 3| may be used as illustrated in Fig. 2 to simultaneously extrude the metal from opposite parts l4 and I5 carried by the springs and 3 may be made in three parts 23,24 and 25.

the thin separator plate 24 being placed between the two outer parts 23 and 25. In this arrangement, the thickness of the thin center plate 24 may be made of a value corresponding to a' desired separation between the tips of the clamping surfaces'at theextreme ends ofth'e' two con-"- tact members 8 and 9, and also maybe used'to insure a flat, concave, convex or other predetermined contour for the clamping surfaces at the tips of the two contacts 8 and 9 which are used to contact directly with the electroded crystal element 18. Also, the position of the thin sep arator 24 between the two end plates 23 and 25 The dimensional of thecomposite die 20 illustrated in Fig.4 may be made 'to correspond to desired predetermined relative lengths for the two extruded clamping pins 8 and 9 which may be made of equal or unequal lengths relative to each other. The partition plate 24 of Fig. 4 may beusedwitha die 20 having a cavity of the shape illustrated by the'cavityi2i in'Fig. 2 or by the cavity 22 in Fig; 3, or having a cavity of other shapes.

Fig. 5 is an edge view of a pressure type crystal unit similar to that illustrated in Fig. l, but havingthe'pair 'of clamping pins 8 and 9 extrudeddirectly'from' the springs 2 and 3. For this purpose; each'of the springs 2 and 3 may, if desired, be embossed with a slight prominence at I in theregion of the longitudinal axis YY thereof, and the clamping pins 8 and 9 may be extruded directly from the spring material at I.

The cantilever springs 2 and 3 may be punchedfrom Phosphor bronze sheet metal strips, and the contact pins 8 a'nd'9 may be obtained by extruding a part of the'top portion of the cantilever springs 2 and 3 into the die cavity 2| or 22 which is made of a small diameter to suit the clamping members 8 and 9. In this way, the two small clamping pins 8 and 9, which are used for directly holding the electroded crystal element H), are provided in precise alignment with respect to each other, the springs 2 and 3 providing the necessary holding pressure of about one to two pounds applied to the electroded crystal plate-l8.

'The die 20 used in forming the clamping members'8 and 9 of Fig. 5 may be of the form described in connection with Fig. 1 and illustrated in Figss2, 3 and 4. Where a die section 20 having a cavity 2| of the form shown in Fig. 2 is used, the shape of the resulting extruded clamping contact members 8 and 9 will be of a contour as illustrated in greatly enlarged scale in Fig. 2. And where a die section 20 having a cavity 22 of the form shown in Fig. 3 is used, the shape of the resulting extruded clamping contact members 8 and 9 will be of a contour asillustrated, in greatly enlarged scale, in Fig. 6 which illustrates an example of the form of extruded contour that may be provided for the clamping members 8' and 9 by means of the cavity 22 provided in the die 20 shown in Fig. 3. The springs 2 and 3 of Fig. 5 may be of the same form as those illustrated in Fig. 1. Figs. 1 and 5 showing edge views of such springs. As an example of a particular form which the springs 2 and 3 may take reference is made to Figs. 7 and 8.

' Fig. 7 is a perspective view and Fig. 8 is a side view of the spring mount illustrated in edge view in Fig; 5' and in Fig. 1 also. As illustrated in Figsr'? and'8', thesprings 2 and 3 may be oppositely disposed; upright and flat triangularshaped metal plates secured to and individually electrically connected with the terminal pins :4 and =5,-respectively, and embedded in the molded insulating base I. A bent perforated flange provided'in the bottom corner portion of each spring Z'and 3 as illustrated in Fig.8, may be staked and welded or soldered to the top'portion of the cor,- responding terminal pins 4 and '5 in order to provide a'good connection. The top .or free end portion 1 of the springs 2 and 3 may be arranged in the region along the longitudinal axis Y--Y and may be there provided at 1 with small circular openings if metal inserts I 4 and I5 are to be used therein as illustrated in Figs. 1 and 2; or with slight inwardly depressed prominences if the crystal clamping members 8 and 9 are to be extruded directly from the spring material itself,

9 as illustrated in Figs. and 6. In either case, the crystal clamping pins 8 and 9 are-formed by extruding metal into a suitable cavity opening 2| or 22 in a suitable die 20 held between the cantilever springs 2 and 3 by any suitable means such as an indexed :holder using the base 'I, the springs 2 or 3, or other fixed reference members as a guide for locating the die cavity along the longitudinal :axis YY of the clamping pins :8 and 9.

Figs. 9 and 10 are perspective views illustrating a die and punch arrangement which may be used for cold-pressing the extruded clamping members 8 and 9 of Figs. 1, 2,, -5 and '6. Figs. '7, 9 and 10 may be taken together as representing, in disassembled or exploded .fo'rm, a complete punch and die arrangement .for'extruding the clamping projections 8 and 9 of Figs. 1, 2, '5 and 6, wherein the die section 29 of Fig- .9 may comprise the die section 29 of Figs. '2, 3 and 4 and wherein the punch members 39 or 3| of Figs. .9 and 1 0 may comprise the compression punch members 3-9 and 3| of Fig. -2.

As illustrated in Fig. 9, means may be provided for aligning the cavity 2| or 22 of the die 28 with respect to the desired location for the longitudinal axis Y-Y of the contact projections 8 and 9 to be extruded. For this purpose, the steel die may be provided on its lower surface with guides in the form of dowel pins 34 and 35 aligned along the axis XX, the dowel pins 34 and 35 being insertable in fitting relation in suitably .placed holes 36 and 31 respectively provided along the axis X-X referred to, in the upper surface of the supporting base I of the assembly, and the lower surfaces of the legs of the die contacting the base to provide a vertical stop so that when the extruded contact points 8 and 9 are cold-pressed into the cavity 2| or 22 of the die 20, they will be at the desired location on the springs 2 and 3 along the longitudinal axis Y-Y thereof.

A suitable compression punch arrangement may be provided for pressing the extruded metal contacts 8 and 9 into both open ends of the cavity 2! or 2 2 of the die 20 As illustrated in Figs. 9 and 10, a pair of similar punch members 30 and 3| of Fig. 2 may be carried by a pair of punch plates or bars 38 and 39 each provided with two holes 40 and 4| which cooperate with two dowel pins '42 and 43 located on each side of the die 29 as illustrated in Fig. 9. The dowel pins 42 and 43 are insertable along the axis ZZ and the axis Z'Z respectively, in the corresponding holes 48 and provided in the punch plates 38 and 39, and act as means :for locating and aligning the punch members 3!) or 3| along the desired location for the longitudinal axis Y- Y of the extruded contact points 8 and 9, whereby by applying a suitable compression pressure inwardly in the YY axis direction, on the two punch plates 38 and 39 and on their respective punch members 39 and 3|, part of the metal at T from the springs 2 and 3 may be pressed into the opposite open ends of the cavity 2| or 22 of the die 29 at both sides thereof simultaneously, thus forming the coaligned contact points 8 and 9 carried by the springs 2 and 9.

As shown in Figs. 7 to 11, it will be noted that the guide dowel pins 3 3 and fit in the holes 35 and in the upper surface of the supporting die holder base i, and that the cavity 2! or 25? of the die 29 is accordingly aligned With the Ion-- gitudinal axis YY desired for the extruded contact members 8 and 9, so that when metal is forced into the ends of the cavity 22 of the die 28, the resulting extruded contacts 8 "and 9 are disposed along the longitudinal axis YY. In order to remove the extruded contact points 8 and 9 from the die 28, the springs 2 and 3 may be bent outwardly .by spreading them apart, thereby removing the integral contact points 8 and 9 from the cavity 22 in the die 20. Thereafter the die 28 may be removed from the die holder base by lifting the dowel pins 34 and 35 from the holes 38 and 31 in the supporting base i. The die 29 may be removed by spreading the springs 2 and 3 apart sufi'iciently to remove the die 29 without scraping or touching it against the fine tips of the extruded contact points '8 and 9.

The extrusion method provided in accordance with this invention for forming the contact members 8 and 9 insures the alignment of the contact projections 8 and 9 without any but rough tolerance consideration in the assembly of the component members carrying the contact points 8 and 9, since the two spring members 2 and 3 may be first assembled so as to be only very approximately aligned in "the direction as indicated by the longitudinal axis YY, and are fixed in such a position with reference to the base The desired length, diameter and shape of the contact members 8 and 9 being known, the die 20 may be made with a cavity 2| or 22 to suit the shape and size of the contact points 8 and 9, and may be disposed between the two springs 2 and 3 with the extrusion cavity 2| or 22 of the die 26 aligned with the desired location of the longitudinal axis Y-Y for the contact points 8 and 9 on the springs 2 and 3.

The cavit 24 or "22 in the die 20 has an inner diameter made equal to the diameter desired lfol the end or tip portions of the contact members 3 and 9, and is made in the die 20 at the desired location with reference "to the longitudinal YY of the clamping points 8 and 9. The ca'vity 22 of the die 20 may be suitably contoured at both of its end openings, to conform with a broadened base portion for the broadened bel=l- .2 shaped spacer base of the contacts '8 and :9 when they merge into the springs 2 and 3 as illustrated in Fig. '6.

It will be noted that the extrusion method of forming the opposite contacts 8 and 9 provides advantages of interest over prior art methods. For example, where the clamping pins are made individually and separately, and afterward are set by soldering or welding in the springs, it is very difficult and not a simple operation to set the contact pins accurately in the springs zprecise alignment; whereas in the integral extruded operation provided in accordance with this invention, the simultaneously extruded pins 8 and 9 may be accurately and easily aligned in one operation, and moreover, the small pins 8 and 9 may be made relatively much shorter in length, as of the order of .006 inch to .002 inch in length, for example.

While one pair of oppositely extruded clamping points 8 and 9 have been particularly illustrated in Figs. 1 to 11, it will be understood that an additional pair of such oppositely extruded contact points may be provided from the same springs 2 and 3 by a similar cavity 2| or 22 in the die 29, in order that a suitable crystal element I!) may be clamped between two such pairs of oppositely disposed clamping points 8 and 9 as illustrated in Fig. 12. Moreover, the invention embraces the idea of the alignment of any number of sets of extruded contactsieach consisting of one or more pairs of contact points arranged in any predetermined direction or combination.

Fig. 12 is an enlarged sectional view, similar to that of Fig. 2, but illustrating two pairs, of aligned contact elements 8 and 9 which have been extruded from four insulated metal plug inserts l4 and I5 carried by a single pair of springs 2 and 3. As illustrated in Fig. 12, one pair of the aligned extruded contact elements 8 and 9 may be located along the longitudinal axis Y-Y as in Fig. 2, and tl other pair of aligned extruded contact elements 8 and 9 may be provided along another axis Y'Y which is parallel to the axis YY. The extrusion of both pairs of contact elements 8 and 9 shown in Fig. 12 may be per- ,formed by methods as hereinbefore described,

using oppositel disposed punch members 30 and 3| for pressing metal from the metal inserts I4 and I5 into the opposite end openings of a suitable die cavity 21 or 22. Where the springs 2 and 3 are composed of conductive material, the two contact elements 8 or 9 that are mounted on the same spring 2 or 3, respectively, may be electrically insulated from each other by providing suitable insulating bushings 59 inserted between each of the four metal plugs Hi and i5 and the corresponding conductive springs 2 and 8, as illustrated in Fig. 12. Individual electrical connections to the four electrically insulated contact elements 8 and 9 shown in Fig. 12 may then be establish-ed by means of four separate conductive wires IBa, individually soldered or otherwise electrically connected at l9b to the four corresponding metal plugs M and l 5.

It will be noted that the arrangement illus- I" trated in Fig. 12 may be utilized for mounting a crystal body, such as the crystal body IQ of Fig. 1, between the two pairs of aligned clamping contact elements 8 and 9, and that if the crystal body [0 is provided with integral electrodes H and I2 of the split or divided type, the four contact elements 8 and 9 illustrated in Fig. 12 may be utilized to establish individual electrical connections with the four electrodes so provided on the opposite major faces of the crystal body Ill.

Such divided type electrodes are well known in the art in connection with longitudinal mode type crystal elements for example where the two pairs of electrodes may be utilized to obtain from a single crystal element two separate circuits of equal frequency, and for other purposes.

While the invention has been described in connection with springs of the general type utilized in pressure type crystal mountings, it may be utilized in other types of contact springs, and although *this invention has been described and illustrated in relation to specific arrangements, it is to be understood that it is capable of applica- .12 tion in other organizations and is therefore not to be limited to the particular embodiments disclosed.

What is claimed is:

1. Extrusion apparatus comprising a unitary die having a single cavity therein provided with oppositely disposed enlarged end openings positioned at opposite sides of said die and a sub.- stantially smaller opening positioned adjacent the central part of said cavity intermediate said enlarged end openings, the openings taken at consecutive points spaced along the length longitudinal axis of said cavity being increased in area from said smaller central part opening outwardly in opposite directions to each of said enlarged end openings, means including a work supporting base for detachably fastening said die temporarily in predetermined relation with respect to said base and constituting guide means for providing a fixed reference axis for said longitudinal axis of said die cavity with respect to the work, and punch means carried by said die and having punch member means disposed adjacent said die cavity and in alignment relation with respect to said longitudinal axis of said die cavity and the work.

2. Extrusion apparatus comprising a unitary die having a divided cavity therein provided with oppositely disposed enlarged end openings positioned at opposite sides of said die and a substantially smaller opening positioned adjacent the divided central part of said cavity intermediate said enlarged end openings, the openings taken at consecutive points spaced along the length longitudinal axis of said cavity being increased in area from said smaller central part opening outwardly in opposite directions to each of said enlarged end openings, and a partition in said die cavity forming a transverse dividing wall across said cavity at said smaller central part opening remote from said end openings, the thickness of said partition wall being substantially uniform across said cavity and made of a value corresponding to the value of the spacing desired between the inner extremities of said divided cavity and the work to be extruded therein.

' JOSEPH F. BARRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 820,586 Marshall May 15, 1906 1,744,810 Shallcross Jan. 28, 1930 1,874,457 Corey Aug. 30, 1932 1,991,140 Currier Feb. 14, 1935

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