US2670640A - Apparatus for foliating wire ribbon leads - Google Patents

Description

P. A. DELL March 2, 1954 APPARATUS FOR FOLIATING WIRE RIBBON LEADS Filed Sept. 1, 1951 3 Sheets-Sheet l Inventor: Paul! A. Dell HIS Attorney March 2, 1954 P, DELL 2,670,640

APPARATUS FOR FOLIATING WIRE RIBBON LEADS Filed Sept. 1, 1951 5 Sheets-Sheet 2 P. A. DELL March 2, 1954 APPARATUS FOR FOLIATING WIRE RIBBON LEADS Filed Sept. 1, 1951 5 Sheets-Sheet 3 n h% 0 e D n @m nu 1 a M D. M y b Hus Attorney Patented Mar. 2, 1954 TED rs TAT-res lPefil fifl afid Heights, Ohio, assig-iior to General =Eletrie Company, a corporation of New York 'hpplieatioirsepteniher 1, 1951, Serial No. 24-4319 5 Giaims; -(Cl. 80--31.1)

' This invention rei'a-tes g'eneraliy'to lame-making mathihery, and 7 more particularly to apparatus for "foh'a-ting or forming a fiat ribbon "portion intoa' leadin wire for a vitreous bulb.

Insealing a lead-in'wire or conductor into' 'a vitreous bulb, it is necessary either that the condu'c't'or 'have the same-'ceefiiei-ent of expansion as the vitreousport-ion into wh-ioh it issealed, or that it he'proportioried"to'yielti to the yitreous portion'durin'g the unequal expansion of the two. Wherethe vitreous bulb is made of transparent quartz" or fused silica, the; first method is in applicable; "The reason for this is 'that quartz has a Very high fusing temperature and its coefficient of f thermal expansion differs greatly from that of air-suitable meta-1s. "'Mdreover, the "choice of "metals" is seriously restri'et'ed 1 because very few can" be worked at the high temperature necessary for-fusing into quartz. Accordingly recoursemust generahy-be-had to the second 'methdd' involving the use offoii or ribbon seals.

With a: quartz bulb; a hermeticor-vacuumtype seal can he formed with molybdenum sheets or ribbons provided that the ribbon-is 'su'ihci'ently thin; The eoefficient of l expansion of molybdemum is r'iearI-y ten times that 'ofquartz sothat stresses maybeset'up'intne latter-owing tothe difierential "expansion between them. Provided the -metal is very thin and :properly bonded to the quartzpsuoh-s'tresses may be in'suihcient'to crack the quartz; In other words, the-metal hatirigbecomehohiied to-the quartz at a relatively' hi-ghtemperature, Will mereiy' go into ten sion when the bulb cools but will not "runtine nor crack I the quartz.

Up to the resent time molybdenum ribbon sea-Is have" generally been produced by welding together thirrstripsof foil orribhon to wires of suitable lengths. The molybdenum foil is out into strips'a few r'rii'ilime't'e'rs wide and of the proper iength requirerifor the seal, and thicker moiyb denumwires are'welded'toe'aeh end of a strip to form'theeurrent connections. The rib ban" or foil "is preferably etched in an electrolytic-bath which deans" the surface thoroughly and roughensit'sli'ghtfy. The bath also dissolves away"- some er the metal so that feather edges-are produced which assists in preventing leakage arotrhd the seai.

It will readily be understood that molybdenum ribbon ieacimresmade" from weIde-d sections require con-si'uerahlemanualiabor'andare Tracessarily very expensive. "Moreover "a" considerable amount of wastage'oocurs dueto the'difiicul'ty of controlling the Wei-ding temperature; addiand the lamps are-worthless tion, ev'en'thoug-hthe weided ribhon'ieads appear satisfactory upon visual inspect-ion, "ver -emu, Wherrthey are subsequently assembied into lamps, it i s round that they break at the welded joints Such suhs'eq'uent breakage during manufacture appears to be due to'the embr'ittl'em'ent and to the contiuuitiesoe curring in the ribbon leads'b'y reason ort etwo welds; it W11 be realized thatthe discontinuities are not only mechanical but --a1so thermal-arid electrical. By eliminating" these discontinuities, not only may the ribbon-lead be made-stronger, but it may also'have a higher-current carrying capacity.

In the copendingU. S. patent-applioation N0. 244,'8l-8,of EdwafdBjNoel-jointly with my'seif, filed Efit. l, 1951, entit1edRibhon Lea-dConstru'ction, and. assigned'to the same assignee as the present invention, there is described a-iih- 'bon iead formed from a single piece'of wire.

Thatlead comprises two round inoTybdenum wire portions forming the ends, and'an intermediate flattened portion through which the seal to the quartz is made. The "iead is -made by longi- *tudina11y' rolling a piece of mblybdenumwire between a pair of 'hargened cylindrical rolls. Such a ribbon lead has the very decided-advantages that-the cross s'eotion changes gradually from a circular one into a flatteneki ellipticaionewithout the occurrence of any sharp discontinuities.

Thus the concentrations or stress whih ooour with ribbon leads made up o'f weld'ed'seotions, are eliminated and the resulting sealis" not one stronger but able to withstand a" higher tempera- '-ture' and to carry a heavier current without The general object of the present; invention is to provide an improved apparatus for foiiating a round -wlre. I

Another object of the invention isto provides; new and-improved apparatusfor rolling a hat tene'd and longitudinally extendedportion into-a pi'e'ceof wire;

The specific object of the" invention" is to xprm vide a 'm'eohanism for produeing the roiled molybdenum wire ribbon lea'ds desoribed inithe previous-1y mentioned eopendirrg "apniic'ation :of

Noel 'et at, wherein the-foliated-portion of the lead is made by flattening and 1st1'etohing'the metal in a direction" parallel tothe axis of "the wire in order to aehieve a longitudinal=eryStaI orientation throughout the round and thefi'at ortions of the read without any sudhem diseoritinuities.

'Inaceordarrce with the invention, a one piece ribbon lead is made by holding a short length of wire, preferably under some tension, between a pair of hardened rolls which are rocked backwards and forwards through a gradually increasing arc. The rolls are mounted in a pair of opposed semi-cylinders journalling in open bearing shoes. Means are provided for forcibly sliding one bearing shoe towards the other, thereby to squeeze the wire between the rolls, and means are also provided for automatically rocking the semicylinders through the gradually increasing are required for the operation.

For further objects and advantages and for a better understanding of the invention, attention is now directed to the following description and accompanying drawings. The features of the invention believed to be novel will be more particularly pointed out in the appended claims.

In the drawings:

Fig. 1 is a pictorial view of a one piece molybdenum ribbon lead such as is produced by the mechanism of the present invention.

Fig. 2 is a pictorial view of a high pressure mercury vapor quartz arc tube constructed with one piece molybdenum ribbon seals.

Fig. 3 is a pictorial view of an apparatus for making one piece molybdenum ribbon leads and constituting a preferred embodiment of the invention, and in which certain portions have been broken away for greater clarity.

Fig. 4 is a fragmentary pictorial view of one of the semi-cylinders and its roll.

Fig. 5 is a simplified diagram, schematic in form, of the control system utilized in conjunction with the mechanism of Fig. 3.

Fig. 6 shows a hydraulic cylinder alternatively as the driving means for the mechanism of Fig. 3 in lieu of the reversing screw arrangement shown therein.

Fig. '7 shows the gripping means or tension pliers which may be utilized for holding a length of wire between the rolls of the mechanism.

Figs. 8a, b, c and d are illustrative of successive steps in rolling a flat portion into a molybdenum wire for making a one piece ribbon lead.

Referring to Fig. 1, there is shown a rolled one piece ribbon lead l as made by the mechanism of the present invention. The lead comprises cylindrical end portions 2 and 3 which are actually the wire from which the intermediate foliated or ribbon-like portion 4 was formed by rolling the wire forward and backward under tension between a pair of hardened rolls. The maximum permissible thickness A of the foliated or ribbon portion 5 depends upon the material of the lead and also upon the vitreous portion into which it is to be sealed. For a molybdenum seal into quartz, the optimum thickness is approximately .0005 inch; thicknesses greater than .001 inch may give trouble with leaks, whereas thicknesses less than .0005 inch are fragile and lack current carrying capacity. The width B of the ribbon portion depends upon the current to be carried and, in practice, varies from about 1 to 10 millimeters. The length C of the ribbon portion depends upon the size of the seal, the temperature conditions of the lamp in operation, and the difference in the expansion coefficients of the lead material and of the glass or surrounding quartz. With copper sealed in glass, for example, the length 0 may be as little as 1 millimeter. With very high temperature mercury arc quartz tubes on the other hand, the seal may be as long as 25 millimeters. For a moderately high pressure mercury arc lamp such as is illus- 4 trated in Fig. 2, the width 13 and the length C of the seal may be approximately 2 and 5 millimeters respectively.

Ribbon leads of the type illustrated in Fig. 1 may be used generally for effecting a seal into a vitreous bulb where it is not feasible to rely on matching the expansion coefficient of the lead metal and of the vitreous bulb for obtaining a hermetic seal. As an illustrative example, there is shown in Fig. 2 a high pressure mercury vapor arc tube 5 comprising a quartz envelope 6, into the opposite ends of which are sealed a pair of main electrodes 1 and 8 and an auxiliary starting electrode 9. These electrodes comprise the ribbon leads I which have been described, one cylindrical end serving as the external connection and the other end supporting the electrode proper within the arc tube. In the case of the main electrodes 1 and 8, small tungsten slipover coils l0 and II are mounted on the inner ends of the lead and enclose a small sliver of thorium metal which serves to increase the electron emission of these electrodes. The ribbon leads may be sealed into the quartz tube by locating them inside a length of cylindrical quartz tubing corresponding to the bulb 6, heating the ends thereof in a reducing atmosphere, and thereafter collapsing the ends by mechanical means, so as to lock the foliated portion of the ribbon lead in the quartz. Alternatively, the seals may be made by vacuum collapse of short lengths of quartz tubing about the ribbon leads, and thereafter fusing these lengths to quartz bulbs.

The mechanism by means of which the ribbon leads are made from molybdenum wire is illustrated in Fig. 3. A length of molybdenum wire is located vertically between a pair of hardened rolls i5 and 16 mounted in steel semi-cylinders I1 and 18, which are journalled in bronze bearing blocks or shoes i9 and 20. The forward faces of the bearing blocks l9 and 20 are shaped to a cylindrical curvature in order to serve as bearing surfaces for the semi-cylinders I! and 18. The bearing shoes are fastened to cross pieces 2i and 22, the former being slidably mounted on a pair of guide rods 23 and 24. Cross piece 22, the standard 25 and the guide rods supported thereby are rigidly fastened to a frame member 26 which serves as a main support for the apparatus. The movable cross piece 2| may be forced against the fixed standard 22 by means of an air cylinder 2'! whereof the piston 28 is directly connected through the rod 29 to the movable cross piece.

The hardened rolls l5 and I6 operate on the wire compressed between them, through a rocking movement. This rocking movement is imparted to the steel semi-cylinders I! and I8 through the cranks 30 and 3| which are attached to them on one side, as by welding. The cranks 30 and 3| are swung up and down by means of a screw crosshead 32 to which they are linked by connecting rods 33 and 34. Crosshead 32 is reciprocated vertically by the two parallel lead screws 35 and 36 which are rotated by a reversible electric motor 3'! geared thereto as shown at 38.

Where the ribbon leads are to be made of some This material is very hard and strong in comrock. "In transmitting the stress tothe semi-# cylinder, the tungsten: carbide roll distributes it over a considerable area and thus the semi-- cylinder c'an safely wlth'stand it, even though made of steel having a -'much lower icom'pressive strengththan tungsten carbide The 's'teel semicylinder :fnr ther distributes the :stress over the face of=the bearing shoe -19 having aryet "greater T bearing area and thereby all'ows the utilization therefor 0f :a relatively soft 'material' 's'uch as bronze; It willbe appreciated that mating surfaces of r steel "and bronze provid'e an ideal comhination-from the-point of view of ease "of lubrication. The side "plate 39 fastened -to the bearing-shoe locates the semi cylinders and the end ofthe'crank why means o'f a small pin 40 which 2 5 enters the circular "projecting portion 41 of the crank along the axis-of rotation of the semicylinder. The tungsten carbide r011 '15 fi-tis in the semi-cylindrical cavity -*42 in the semicylinder and may be welded i'o'r soldered in pla'ce. This arrangement detains the semi-6ylinders in place when the are withdrawn one from-the other; 1 duringzthe rolling operation, ofcourse, the compressive stresses are-taken up by 1 the 'bearing shoes. flhe arrangementzpermits the'application of compressive stresses in lthe rangeiof 500,090 pounds :per square inch to the -molybdenum wire in orde'r to roll a flat-portioninto it.

In the rolling operation, it is desirable-that the arc-of rock ofithe rollsbe gra'dually increased" as the middle portion of the molybdenum wire becomes flattened and elongated. It is also rererable thatthelpressure exerted on the rolls be likewise increased'since the ribbon-portion of the wireincreases in width as-it decreases in thiek-= ness. Thus the wire offers an increasingly'l greater bearing area against the rolls' as itis gradually flattened, therebyrequiring an increase in the'compressive force in order to -mainta-inthese-me pressuieper unit areaonthe wire. 'Ih'e' control system by means ofwhich these-operations are efiected is schematicallyillustrated in' Fig. 5.

Referring to Fig. 5, the-arc of-r'ock of the rolls is directly dependent on the throw 01'. vertical displa'ceme'nt of'crosshead 3'2, which in turn is controlled through the limit switches K-l and K-2 mounted thereon. These limit switches close when they contact upper and lower limit. tabs 5c and 51 which aremounted on the periphery 1 of a-rotatable cylinder 53. Cylinder 53 has been illustrated in developed form for greater clarity. The limit tabs 50 and 5| are stepped so as to provide a gradually increa'singstroke to the cross headed The'electric motor 3;! is of a :three phasetypev and is connected :for energization from a three phase supply at the terminals 54, the phases being indicated by A, B, andC. :Asis well-known, the directionof rotation of suchi a motor may he reversed by interchanging two of theiphase' connections. This is done through the reversing switches K-3 "and K4, "the fQ'rmerLbeing the deem switch and the latterrthe up iswitch. When switch-K 3, is closed, motor 31 rotates so as: to. move crossheadv 32 :down, awherea's wheii switch K4! is closedfithe motor reverseszso as tomove the crossheadiup. The operation ol. the

reversing relays K 3 and rK-4 :is effected :throug'h control relays :Kefi, K-=6, respectively.

The ope'ration of the control system may be understood most readily by following th'e 's'e quence of actions through one cycle fof reversals I between a set ofllimit switches. The-operation is initiated 'by imomentarilyapre'ssing startiswitch 55. Thiszi's equivalent to closing the upper limit switch 1111-! andcompletesia-"circuit fromiiphase A 1 through. conductor '56, switch A 55, coil 5'! of relay Kai-conductor ea stopswitchzfillaand-conductor (it to :phase 3. Immediately, control relay 'K-5 operates and its holding contacts 61 closegso' tliat the relay is ithereafterheld closed, independently of the star'ting i'switch 55 or :of the limit 'swltch K4.- =The holding circuit is completed to ph'ase- A through the normally clo'sed contacts 6:2 or

relay Ii -'5, I and to phase B through conductor- 88 stop switch :59, and conductor 50. When easy K-s is energized, its lower 5 contacts 63 close and energize coil "64 of the -down reversing switeh K 3 so that cross'head 32 begins its downward stroke. 7

The momentary elosing of the startswitch 55,

or of "the upper limit switch K- l on subsequent strokes also serves'to energize ratchetrelayK l.

Th-i's relay is arranged to 'rotate cylinder' lit llitermittentl y by means 0f the paw15to which its armatureis-linked, and the r-atchet-teeth fl on the underside of cylinder $3, which the panel engages. As a result, the cylinder -is "indexed through one position in thedirection fo'fthe' -arrow 53, and the 'iirst pair ofliini-ttabs 59 "and 51 are brought into alignment withthelimitswitches K- i and K-E.

The crc'sshead- 3 2- continues its downward stroke until the lower limit switch K 2 strikesthe first lower limit tab 5!. A-circuit is thereupon completed' from phase A to phase B through the coil a? of relay K-e. gized,'its normally'cicsed contacts 62 open and break the holding circuit which liad "previously been holding relay'K-li energized. The normally closed'contacts $8 of relay K-"E thereupon=reclose,

and a holdin'g circuit for relay K-ii completed through "its normally open contacts-Bil and the normally closed contactstliof'relayK Therea'iterrelay 'K-t remains closed independently-(if the limit switch K Z until the "time when the normally closed contacts 68 of relay K-"ii are opened. This-occurs when the upper limit switch K' strikes the top limit tab 52 for the next reversal "of the stroke, The circuit for energizing the controlcoil Iii-of down relay K4 is corn-- pleted-through the lowercontacts H of relay K-S.

The stroke or throw of the crosshead 32 isthu's determined by the location of the limit tabs 50 and 55. In'thejpreferred embodiment of tite -invention, these limit tabs are disposed stepwise selectively-admitted to-the cylinder through one the control coils are arra'riged for energization As soon as relay K 5 is ener through circuits including the switches 82, 83 and 04 respectively. These switches are closed in sequence by the cam surfaces 85, 86 and 81 on the cylinder or drum 53 as it rotates.

At the end of the rolling operation, the air pressure is released by the operation of the solenoid valve 88. This valve is energized through the circuit including switch 09 which is closed by the cam surface 90. At the end of the cycl the mechanism is brought to a stop by switch 59 which is momentarily opened by the short cam surface 9|. As a result, the return circuit for relays K-5 and K-B through conductor 58 is momentarily opened so that the holding circuits of both relays are simultaneously broken and the apparatus comes to a stop.

Although the mechanism, as illustrated in Fig. 5, achieves the rocking of the rolls through a reversible electric motor and lead screw arrangement, it may be more convenient for a large scale operation to utilize a suitable hydraulic cylinder whereof the piston is provided with the necessary length of stroke. This is illustrated in Fig. 6 wherein the connecting rods 33 and 34 are pivoted through pin I on the upper end of rod IOI of a piston I03 sliding within a cylinder I02. The control system utilized with this arrangement is substantially the same as that illustrated in Fig.

with the exception that the reversible solenoid swiches K-3 and K4 are now replaced by a pair of solenoid hydraulic valves I04, I05. Pressurized fluid, for instance water or oil, is supplied to these valves through an inlet tube I05, and the connections to the control coils I01 and I08 are made to the remainder of the control circuits shown in Fig. 5 precisely as for the control coils 64 and I0 of the reversing relays K-3 and K-4. It will be understood that the limit switches K-I and K-2 are mounted on the upper end of the rod IN and travel therewith in the same way as with the screw crosshead 32 of Fig. 5.

During the rolling operation, it is desirable that the wire be held vertically between the rolls, that is, normal to the plane through the axes of the rolls, and under a slight tension. The tension is required in order to take up the lengthening of the wire which occurs as the fiat portion is rolled into it. A. suitable pliers or gripping device for holding the wire is illustrated in Fig. '7 and comprises a pair of rods I09, H0.

Rod H0 is rigidly attached to a block III serving as a handle, whereas rod I09 is pivotally mounted and is sprung out by means of a hairspring H2. The lead wire I is held across the forward ends of the rods by means of wire loops H3, H4 which are maintained in tension by the.

coil springs H5, H6. The tension in the loops I I3, I I4 may be relieved by squeezing the releasev levers H1, H0 which are pivoted on the rods I09, IIO respectively, and engage the fastening buttons II9, I20 of the wire loops.

In order to hold the lead wire I between the rolls I5 and IS, the gripping device with a wire, fixed across its ends, is located with its longer.

dimension parallel to the axes of the rolls and is held in place by suitable means. Then, as

the lead wire I is gradually lengthened throughv its length; At this time," the air piston 21 ex-' erts the least pressure on the bearing shoes and the rocking arc is the least, as indicated by the relatively short curved arrows I2I. Figs. 8b and 8c illustrate intermediate stages in the rolling operation wherein the pressure exerted by the air cylinder 2'! has been increased and the rocking arcs have been lengthened, as indicated by the arrows I22 and I23. In Fig. 8d the pressure exerted on the rolls is at the maximum and the arc of rock, indicated by arrows I24, is also at its longest.

It will be understood that the type of foliating operation described above has the advantage that the wire is not merely flattened out from a round or circular cross section to a flat one, but

is in addition elongated. Thus the cross sec tional area of the wire through the ribbon portion is considerably less than the cross sectional area of the regular or cylindrical portion at either end. This has the advantage of producing a streamlined flow or orientation of the grain structure and results in a much stronger ribbon lead than would be obtained with ribbon leads produced otherwise than through the present longitudinal rolling operation.

The mechanism which has been described may be used for rolling molybdenum and tantalum wire at room temperature. In the case of tungsten, the wire is less ductile and the operation may be assisted by heating the wire, as by passing a current through it, while it is being rolled.

'While a certain specific embodiment has been shown and described, it will of course be understood that various modifications may be made without departing from the invention. It will also be understood that the details of the control system and the mechanical means for securing the necessary operation of the rolling members may be changed within the scope of the invention as defined by the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for foliating a portion of a wire, comprising a pair of opposed semi-cylinders each having a generally semi-cylindrical axial cavity and a substantially cylindrical roll mounted axially within the cavity, open bearing shoes backing the semi-cylinders, means for forcibly sliding said shoes one towards the other thereby to squeeze a wire located between the rolls transversely to their axes, and means for rocking said semi-cylinders, thereby to draw said wire backwards and forwards between said rolls.

2. Apparatus for forming a one piece ribbon lead having a foliated center portion and cylindrical end portions, comprising a pair of hardened cylindrical rolls composed of a material having a relatively high compressive strength,

a pair of opposed semi-cyiinders composed of a ened cylindrical'rolls composed of a material inders synchronously through gradually increasing arcs, thereby to draw said wire backwards and forwards between said rolls with a gradually increasing stroke.

4. Apparatus for forming a one piece ribbon lead having a foliated center portion and cylindrical end portions, comprising a pair of hardened cylindrical rolls composed of a material having a relatively high compressive strength, a pair of opposed semi-cylinders composed of a material of lesser compressive strength and having generally semi-cylindrical cavities each receiving one of said rolls, open bearing shoes journalling said semi-cylinders, a sliding mounting for said shoes allowing one to be displaced towards the other so that said rolls contact each other along a line parallel to their axes, means for forcibly sliding said shoes together thereby to squeeze a wire located between said rolls transversely to their axes, crank arms attached to said semi-cylinders, a crosshead, rods connecting the outer ends of said cranks to said crosshead, and means for reciprocating said crosshead through a gradually increasing stroke, thereby to draw said wire backwards and forwards between said rolls with a gradually increasing stroke.

5. Apparatus for foliating a portion of a wire, comprising a pair of opposed semi-cylinders each having a generally semi-cylindrical cavity and a substantially cylindrical roll mounted axially within the cavity, open bearing shoes backing the semi-cylinders, means for forcibly sliding said shoes one towards the other thereby to squeeze a wire located between the rolls transversely to their axes, crank arms attached to said semi-cylinders, a hydraulic cylinder having a reciprocable piston, means linking the outer ends of said cranks to said piston, solenoid hydraulic valves controlling the admission of pressurized fluid to said cylinder, limit switches supported from said piston and connected in a control circuit with said solenoid valves, a plurality of spaced stops cooperable with said limit switches, and means for advancing different stops into position for engagement by said switches at successive strokes of said piston.

PAUL A. DELL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 293,292 Williams Feb. 12, 1884 848,630 Cameron Apr. 2, 1907 1,384,485 Putnam July 12, 1921 1,536,777 Day May 5, 1925

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