US2373861A - Method of making contact wiper springs - Google Patents

Description

April 17, 1945. c. VAN INWAGEN, JR 3,

METHOD OF MAKING CONTACT WIPER SPRINGS Filed Oct. 8, 1942 2 3 .7 d o o o o o o o o od FIGS. 4 q Hag;

' INVENTOR C. 4.144N INMGLW, JR;

A TTORNEV Patented Apr. 17, 1 945 more ' METHOD or MAKING CONTACT WIPER Van-Inwagen, Jr., Rutherford, N. L,

Charles L;

" massignor toBellfiTelephone Laboratories, In-

I corporated," New york, N. Y.,' a" corporation .of

New York Applicationflctober s, 1942, Serial No. 461,285 5 i ffg'c a'i (01. 29-45555) 4 This invention relates to improvements'in'elc- -trical contacts and particularly to contact members used in switching mechanisms in the tele''- phoneart. I

An object is to saveprecio'us'metal in the manufacture of such contact" members and to erfeet other improvements therein. I I

Heretofore contact members such. as relay springs and switching springs have been 'inade,

with. precious metalinsertsoriinlays servingas contact points, providing a precious metal strip along the center of a base metal strip androlling' or otherwise securing the two members together and then punchingout thesprings with'the c'ontact endsof two opposite springs registering end to end on the precious metal portion- Other methods of manufacturing spring having pre The present invention relates to improvements in these prior methods; andaj feature thereof is a more efficient method of-manufacturing base metal springs or wipers having contacting ends consisting of a solid tip of'preciousme'talfi More specifically, this method consists of inse rting' billets of precious metal at intervals in a strip: of

- base metal, riveting and-welding. these billets to the base metal strip and then coldrolling the strips without annealing to. givethe required spring temper and thickness forthewiper s. Out

of these strips may then be punched a seriesiio'f wipers with the tips of two opposite wipersmeet ing in a corresponding separate precious metal insert so that each wiper'will' be provided with a solid precious'metal contact tipand so that there will be very little waste of the precious metal in the scrap material after the wipers are punched out. An advantage ofthis method is that wipersof widely difierent shapes may be punched out from these strips without increasing" the waste of the precious metal inserts. The invention has been. illustrated in the"ac companying drawingin which? F '1 shows a base inetal strip' with apertures in a. row and along the central line of the stein Fig. 2 is a cross-section takenfon line 2-- -'2 of Fig-L I Figs. 3 and 4 show enla rged cross-sections'of individual billets in the base metal stripi -j Fig. 5 is a'front view o! the, base'jmetal strin and inserts rolled out to 'a' desired'thic'kness' "with a particular type of wipers indicatedffor punching out of the strip.

Fig. 6 shows a cross-section of Fig. 5: and

taken on line 8 6 Fig. 7 shows a wiper assembly on a shaftas'so} ciated' with terminals in a switch'bandj. :3 The method of manufacturing thesewipers as illustrated inthe drawing may be described: as

follows: a I I I In the base metal strip I, a series of holes such as 2 may be punched through the central line of the strip and intermediatethe'se'holes-may-be punched smaller holes such as 3; These holes 3 may be used'as guide holes as will 'be'described hereinafter; 111 the holes 'or openings 2 are inserted billets 4 of precious metalwhich are slightly thickerthan the base metal. sheet I as shown in the enlargement of'Fig. 3; The'next stepwill be to rivet this billet 4 as "shown'in Fig. 4 to -the base, metal sheet I vto'provide a' slight overlap ofthe enlargement of the rivet on-each side of the sheet as shown for example at points 5 and. 6 on opposite sides of the rivets. These riveted bil let may then be welded tb'ba'se me talshee'tby heating the assembly to a critical'tem perature suitable to. the character: of the'ins'ert material so that this billet Will 'llllite withth'e' base metal sheetin a perfectweld. N This welding or'bonding of the billetto the base metal sheet may be accomplished, for example, by? the method dis closed in the Patent 2,226,944 of December 31, 1-940 to'H. T. Reeve. This strip of material may now be rolled down to the required thickness,"that is, it may originally be of .such thickness that when it is rolled down'without annealing to a desired thickness the right spring'tefriper'required for the wipers will be obtained. An approximate'indica-.

tion of the relative'size and thickn ess of the original sheet as compared with the" sheet as; rolled out may be had by comparing Fig; 2 with Fig. 6. As shown in Fig. 5 wipers maybe punched out from this rolled out sheet arranged-in the manner indicated Wipers having this' par-tic'ularshape may be employed in telephone switches in pairs as shown for example in Fig. v'T-where they are assembled with an'intermediate insulation plate on a bushing which isse'curedto'ashaf-t. These wipers may engage terminals onfo pposite sides of an insulation sheet in a'b'ank. It should be noted in Fig; 5 that duetothis'shape; a 'convenient way of savingas much as possible-"0f the precious metal inserts and the base'metalsheet, a pair of wipers such as are indicated 'for example at 20 and 2| "maybe punched outwith the tips meeting end toend ona' precious metal insert 22 which has been'shown as'slightly'elong'ated due to therolling out of the strip. The intermediate holes between these precious" metal-inserts may serve as guide holes to locate the 'shee't 'when fit is passed in the punch press and thepunche's' may be of any suitable arrangementfor'exampletl'iere of punches may be arranged side by side to punch out simultaneously a large number of wipers. It is immaterial how this punching is done as long as the tips of the wipers are located in succeeding precious metal inserts and the wipers are so located on the strips as to leave very little scrap material after the wipers have beenpunched out. 1 While a particular form of wiper has been shown.

suitable for use in switching apparatus of the telephone art, it is to be understood that this method of punching out wipers. or springs may be applied to other forms without departing from the spirit of the invention as long as the contact tips consist of solid sections of precious'metah punched from individual billet as inserted and formed in the base metal sheet and as long as the size of the precious metal inserts are:. adjusted t s ure minimum amount ofawastegmateriall 1. Whatisclaimed is:

l. The method of making contact. wiper springs comprising welding inserts. of a precious metal at intervals in apertures. in a base metal strip, cold-rolling the strip to athin elongated strip having a desired spring temper, punching wiper springs in pairs from'the strip with the tips of each-pair of wipers registering end to end on a separate precious metal. insert to provide each wiper with a precious metal contacting tip.

2. The method of making contact wiper springs comprising welding inserts of a precious metal at intervals in apertures in a base metal strip, coldrolling the strip to a thin elongated.- strip-having a desired spring temper, punching wiper springs from this stripin pairs with the-center line-of each pair of wipers running diagonally across the strip and the central lines of two adjacent pairs running par'allel so that .the contact tips of each pair register end to end and include a portion -of the same precious metal insert. i

3. .The method of makingcontact wiper springs comprising welding inserts of precious metal in individual apertures in a base metal strip with the apertures located equidistant apart along-the longitudinal center line of saidstrip, cold-rolling said striptoa desired thickness and spring. temper, punching wiper springs from said strip-with 1 the center line of each pair of wipers running at an angle to the said longitudinal central line. of the strip and in parallel relation to each other and with the tips of the wipers-of eachpair registering end to end on a corresponding precious metal insert so that each tip will contain an equal portion of said insert. p

4., The method of making contact wiper springs having comparatively large surfaceareas at their supportin ends as compared with their contact-.-

ing ends, comprising'riveting and welding rivets of a precious metal of a desired-cross-sectional area at predetermined intervals in apertures in a base metal strip, cold-rolling this strip lengthwise without annealing to .a thickness and extent until the strip has acquired a desired springtension and then punching said wiper spring incpairs from the strip with the contact ends of each pair having their supporting ends of approximately sixto 'seventimes larger surface areas than the surface areas of the contacting ends, comprising riveting and welding rivets of a precious metal of s "a: predetermined cross-sectional area at certain fixed intervals in apertures in a straight line along the center of a base metal strip, cold-rolling this strip in the directionot said center line and with out'annealing the'strip until it acquires a dem sired. thicknesasurface area and spring temper and then" punching said wiper springs from this strip with the wipers arranged in pairs having their contacting ends abutting each other and with said contacting ends of each pair located in 1 a separate precious metal insert and containing when punched out ,the major. portion *of: the enlarged surface-area "or said insert and having their supporting ends located-in: the'base metal sections on opposite sides of the said center line at; an angle and closely fitted together so that when a series of said pairs are. punched out they contain the major portion or the material of said sections. '2 1" 6. The method of making. contact wiper springs having their supporting ends of comparatively large surface areas as compared with the surface areas of the contacting ends comprising riveting and welding billets of .a precious metal of a crosssection 1 of. the .desired;configuration at certain fixed intervals in apertures in a. straight line through the longitudinal center of a base metal strip,. cold-rolling the :stripin. the direction of said center'line without annealing. thestrip to a desired thickness and spring temper and then punching'said wiper springs from said strip in pairs withthe contacting. ends of each pair punched out of a 'separateprecious metal insert andoccupying close tothe entirecross-sectional area of said inserts with; the. contacting-ends and 40 supporting ends of each pair located in a straight line. atan angle to the longitudinal center line of the strip'and through-the centeroi the associated insert and with the enlarged supporting ends of adjacent pairs of wipers occupying a major portion of the base metalisuriace or the strip on both sides of the center line of the strip.

7-. The method of making. contact'wiper springs having large. surface areas at their-supporting 5 ends as compared-with their contacting ends comprising riveting and welding. a;series Of'blllBlZS-Of a precious metal of a suitable cross-sectional area in apertures at equal distances apart alongthe center lineof a base metal;strip,-cold-rol 1ing said strip lengthwise without annealingauntil the desired thickness "and springtemper; has been obtaind and the billets have been-elongated to 'a certain-size and punching out irom said strip .wipers of the above-mentioned configuration and arranged in pairs with the contacting ends of each pair abutting and located in separate elongated billets so as to consume all but ;a minorportion of said elongated billet and iurther arranged so that the central line through the wipers-eta pair is located at an oblique angle across the stripand the elongated surface-otthe corresponding billet with the enlarged supporting. ends of each pair nesting close between the contacting and the'supporting ends-of adjacent-pairs on opposite sides of the associated-billets .and close-to the outer .70 edge ot the strip so that the. wiper. portions CHARLES L. VAN rNwAe n,

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