US1575994A - Lead-in wire and gas-tight seal and method of making the same - Google Patents

Description

March 9 1926. l 1,575,994

C. A. LAISE LEAD IN WIRE AND GAS TIGHT 'SEAL AND METHOD OF MAKING THE SAME Filed Nov. 9, 1923 /WC/re/-J/ee/ 27 A 0 Y ZZ 53(4- A lll/1115111111.

v//lll/I/lll/1111111111111 Aww :a v en sar CLEMEN S A. LAISE, OF TOLEDO, OHIO, ASSIGNOR T0 THE ELECTRON RELAY COMPANY,

f A CORPORATION OF OHIO.

LEAD-IN WIRE AND GAS-TIGHT SEAL AND METHOD OF MAKING THE SAME.

Application 'filed November 9, 1923. Serial No. 673,781.

To all whom it may concern:

Be it known that I, CLmrnNs A. LAIsE, a citizen of the United States, and a residentof Toledo, county of Lucas, State of Ohio, have invented certain new and useful Inlprovements Same, of which the following is a specification. v

This invention relates to lead-in wires and gas tight seals for use in apparatus, such as incandescent electric lamps, gas filled lamps, mercury rectifiers and similar apparatus, in which an envelope of glass or vitreous material is used and in which it is necessary to provide means forconducting electrical energy from a power circuit to conductors l within the space enclosed by the envelope,

and in which a gas tight seal is desired between the vitreous wall of the envelope and the wire passing therethrough.

In order to make a seal for such apparatus which will be gas-tight, the lead-in conductor used should preferably have a co-eflicient of expansion which does not tend to shrink away from the material or to cause. the formation of cracks or fissures as the apparatus is subjected to changes in temperature. It is also necessary that there shall be a 'certain aflinity or adhesion be tween the surface of the conductor and the material -otl the envelope when in a softer plastic condition, in order that there will be a tendency for the two to stick together, and to avoid all surfaces between the wire and the material of the envelope in which the adhesion between the-wire and material of the envelope is weakened or which may tend to permit cleavage or the seepage of as. I

In the earlier lamp constructions, platinum was customarily used for lead-in 'wires because of the fact that it was practically non-oxidizable, has a co-ecient of expansion nearer t0 that of the glass used than other metals and that the glass tends to wet, and stick to, the surface of the wire. Be. cause of the geat cost of platinum, alloys of metalsrwere sought, the composition of which might be so proportioned as to make in Lead-In Wires and Gas-' Tight Seals and Methods of Making the the co-efiicient the same as that of the glass used as the envelope. An alloy of nickel and steel may be made of the same expansion as that of the glass or of smaller expansion but when wires of this alloy are used a film of oxide tends to form at the temperature required for sealing the glass about the wire'which is more 'or less porous and allows air to gradually leak through the wall of the envelope abOut the conductor. This defect has been very largely overcome by covering the wire with a sleeve of coating of copper, the thickness of the copper sheath being so proportioned to the diameter of the inner core of nick-steel alloy that the net co-elicient of expansion is approximately the same as that of the glass i-n which the wire is sealed. In wires of this character a film of oxide tends to form on the surface of the copper sheath, thus causing a Weakness in the seal because of the tendency of the copper to pull away from the intervening layer of copper oxide. This layer of oxide introduces a weakness in the seal between the Wire and glass which may be' tion has always been very tedious and expensive and usually resulted in the formation of knots at the weld, which, if the knots were large, would cause cracked seals. Moreover, because of the diiiculty of making such welds without the formation of excessively large knots, on wires of small dimensions considerable skill was required on the part of the operator and this resulted in making of a number of unsuccessful welds until the operator had become efficient enough to carry out the operation successfully.

These various deficiencies are obviated by my invention which provides a seal in whichthe glass or vitreous material is in intimate or sealing contact with the metal of the lead-in wire. In the interest of form-v ing an effective seal of this type, the invention also provides a leaddin wire by which an eiective seal of thischaracter may be readily obtained," and layers of loosely adhering or separating tendencies between the body of glass and the metal may be avoided, and provides methods of forming'a composite metal` wire adapted to this purpose and of sealing the wire in the glass. The invention moreover provides an improved junction or vjoint between wires on opposite sides of the vitreous wall and methods of forming this joint and of sealing it in the vitreous wall. f

With these and otherl objects in view, the

invention comprises the articles and methods described in the following specification and claims.

In providing a wire particularly adapted Y to avoid the formation of a layer of oxide the g ass accordingly has a light golden, or

- straw colored appearance, or the same color as freshly cleaned copper, indic'atingthe absence of the customary 'layer of red oxide or berate of copper, and indicating a direct adherence of the glass to the copper. Because of the greater tenacity of the union of the' glass to the wire, wider variations between the co-eilcients of expansion of the glass and metal of the wire, due to variations in the composition of the glass, do not aii'ect the seal tothe'extent to which less tenacious unions would be aii'ected.

The wire may be formed by enclosing a rod of the nickel steel in a sheath ofv silver of the proper relative thickness, then enclosing this lcomposite rod in a sleeve of copper and welding the same thereto; then reducing the rod to a wire of the desired'size by the usual swaging, annealing and Wire drawing operations.

` The composite wire may be formed, however, as a sealing portion of `a lead-in wire While forming a junction or connection between a wire, of copper, leading from the wall'ofthe envelope. and a wire, of nickel steel, leading to the interior of the envelope. vFor this purpose, a socket or tube is formed in the end of a wire of copper to a depth equal to the length of wire to which the glass is to be sealed and into this socket is inserted Athe end portion of a core wire, of

wires, This facilitates the electrolytically.

nickel steel, providedwith a silver coating.

The socket of copper is then welded by suitable heat, and preferably withppressure, and

is then sealed in the wall of vltreous material. The sheath and core are thus parts of,

and integral with, the wires on opposite sides of the wall'of glass and the necessity of welding at either side of the sheathed wire is avoided, together with the objectionable knots incidental thereto.

- Theinvention is illustrated in connection with the accompanying drawings, in which,

Fig. 1 is a side view, partly 1n section on a greatly magnified scale, ot' a wire embody- I ing a preferred form of the invention,

Fig. 2 1s a cross sectional view of the wire Ashown in Fig. 1,

Fig. 3 is aside view of a hollowed or socket wire and a core 'wire in position to be inserted therein to form a joint and composite sealing wire,

Fig. 4 is a longitudinal section of the wires of Fig. 3 after being joined,

Figs. 5, 6 and 7 are longitudinal sectional views'of modified forms of junctions and Fig. 8 is a section through a vitreous wall Aat the place in which a lead-in wire is sealed therein, all of the above views beingon .a greatly magnified scale. A u

Fig. 9 is a section through the stem containing the lead wire.

Fig. 10 isa cross section of the stem of va press of a container or bulb containing the lead wires illustrating the seal.

Fig. 11 isa front View of a welding apparatus for forming 'the junctions ofthe wires illustrated in the above figures, and,

Fig. 12 is a side view of the welding :1p-

`paratus shown in F ig. 11.

' In making a lead-1n wire for use in glass seals, such as employed in ordinary incandescent lamp manufacture, I employ as a core metal a nickel-steel having a percentage by welght of about 42% to 43% maximum of nickel. First a silver sheath and then 'a copper sleeve are mounted over this core each of su-fcient thickness respectively to give the resulting composite wire a co-eilicient of expansion approximately the same as that of, glass.

n forming a continuous composite wire, a nickel steel rod 12, is carefully and uniformly turned'down to a diameter of 0.73 inches and upon this rod'l a layer. of silver 14vof from 4 mill to 15 mill i. e. from four one thousandths to fifteen one thousandths of an inch, in thickness is deposited thereon This silver coated rodis then placed inside of a carefully cleaned copper tube 1-6 having an insidediameter of 0.7 56 of an inch and an outside diameter of`0.875 of an inch. Instead' of electrolytically depositing the silver, I may place l-lll on the nickel-steel core an intervening layer of sheet silver 4 mill to 15 mill thick and cut to the right size so as to close up the gap between the nickel steel and the :opper tube.

The constituents of this composite rod are then forced against each other by swaging and are then placed in a vertical gas furnace and welded in an atmosphere of hydrogen at the melting point of silver. After cooling, the rod is mechanically reduced by swaging and drawing operations well known in the art, the compound rod being intermittently annealed as it hardens. The wire is finally drawn through diamond dies to reduce it to the desired diameter. The resultant wire has a co-efticientof -expansion very nearly that of glass. The composition of the wire by weight is about 83% to 70% nickel-steel, 16% to 22% copper and 1% to 8% silver. Vhen this wire is sealed into glass at the proper temperature to produce a tight seal, the resulting seal is straw colored or golden, but if insufficient heat has been applied it appears red. difference is very marked it is easy to determinel Whether a suliiciently high temperature has been used to produce a tight seal in any specific case. The straw color of the seal indicates that the red copper oxide or borate has disappeared or isabsent and that the union is directly between the glass and the metallic copper. The seal is consequentve strong and tenacious and is not afected by slight dilerences in the co-efficients of expansion. I

In lieu of using a continuous copper and Silver sheathed nickel-steel wire, a Suitable copper and Silver sheathed lead-in section may be made from separate pieces of copper and nickel-steel wire. For this purpose, one end of a copper wire 20 is provi-ded with a socket or tubular portion 22 into Which the end of a nickel steel wire may be inserted. The sockets are about from fg@ to 3/3 of an inch in length and may be formed in any suitable way. Fpr example that illustrated in Fig. 3, preferred for wires of small diameter, may be made by llattening the end of a copper wire and then drawing it through a die to form a Socket or tube, the operation being done on an automatic machine. As illustrated in Figs. 5, 6 and 7, the socket may be Idrilled into the end ot a copper wire, these forms being preferred for wires oie larger diameter and larger Current capacity.

For the core portion of the joint the end portion of a nickel vsteel wire 26 is used. A layer of silver 27 is deposited or formed on the end portion of this wire which is to be inserted into the copper socket, the end portion is then inserted into the copper socket and welded thereto, the layer of silver assisting in forming a weld.- The nickel steel As the color' a reduced stem 28 to tit the socket as indicated in Fig. 6. The joint may be welded between grooved electrodes of carbon, graphite or of metal to which the copper will not stick or in a tiame or furnace in which the wires are heated to the required temperature. The use ot pressure in this connection is preferred.

The formation of the seal by joining to` gether the ends ot' separate pieces of copper and of nickel steel wire, as above described, is productive of important results for the reason that in view ot'A the fact that the nickel steel entering an evacuated chamber has not the deleterious feature that a copper covered wire may have in that the possibility of the volatilization of copper in vacuum is thereby eliminated.

V,In electrically welding the joint, an electric welding apparatus ofthe typeillustratcd in Figs. 11 and 12 may be employed. In this apparatus. one grooved carbon contact 30 is attached to an arm 32 pivoted on a support 34 connected to one Aside of an electric circuit and the other grooved contact 36 is mounted on a table 38 and is connected to the other side of the electric circuit. In

.forming the weld, the end of the nickel steel wire 26 is inserted into the socket 22 of the copper wire 20 and placed on the grooved contact 36. The arm 32 is then depressed by means of a foot-treadle 40, connected to the arm, then bringing the contact 30 down on the wire union, simultaneously heating and pressing the union. As the foot-treadle is released, a spring 42 acting on the arm 32 withdraws the contact 30 from the union, automatically opening the circuit ard permitting the removal of the joined wire.

By means of my invention, separate wires may be joined through a sealing in wire without the necessity of forming separate welded joints and without the objectionable knots incident thereto. The invention provides in any of its forms of embodiment, a lead-in wire and sealed wire having a great tenacity for the surrounding vitreous material. Slight deviations in the co-etHcient of expansion of the wire fromthat. of the glass are not as dangerous to the seal as in the case of less tenacious seals.

As changes of construction could be made within the scope of my invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim and desire to secure by Letters Ratent is: j

1. In a device of the type described, a lead-in wire comprising a metallic core, a

. tervening layer of metal between said core and said sleeve having a different thermal conductivity than that o f said sleeve the thickness of said intervening layer being` such as to cause a bright, copper colored surface on said outer sleeve when sealed in glass 2. In a device of the type described, a lead-in wire comprising a metallic core, a copper sleeve surrounding said core and a silver sheath between said core and said sleeve the thickness of said intervening layer being'such as to modify the heating char' acteristics of said wire and produce a copper colored surface thereon when sealed in glass.

3. In a device of the type described, a leadein wire comprising a nickel-steel core, a sleeve of copper surrounding said core and an intervening sheath of silver between said core and said sleeve the thickness of said intervening layer being such as to modify the heating characteristics of saidwire and produce a copper colored surface thereon when sealed in glass.

4. In an article of the type described, a lead-in wire comprising a core of nickel-steel containing between 42% and 43% of nickel, a sleeve of copper surrounding said core and an intervening sheath of silver between said corel and said sleeve the thickness of said intervening layer being such as to .modify the heating characteristics of said wire and produce a copper colored surface thereon when sealed in glass. l

Y5. In an article of the type described, a wall of `vitreous material, a lead-in Wire extending through said wall, a sleeve of copper surrounding said wire and an intervening layer of a metal between said core and said sleeve and welded to said core and said sleeve, said vitreous material being fused to said copper sleeve and said copper sleeve having a clean, copper colored surface of union with said vitreous material.

6. In an article of the type described, a

wall ofvvitreous material, a wire core of' nickel steel, a copper sleeve mounted on said core and an intervening sheath of silver between and Welded to said core and said sleeve, said vitreous material being fused terial having a freshl wall of vitreous material, a lead-in wire in said wall, said lead-1n wire having a nickel'- steel core containing approximately 42% of the surface of said copper sleeve in said ma? l cleaned appearance.

9. A `method of sealing lead-in wireslhav# ing a copper sleeve which comprises fusing vitreous material about said sleeve at a temperature suflicient to remove the color of red oxide of copper from said sleeve in said fused material.

' 10. A method of sealing lead-in wires hav-A ing a copper sleeve and a layer of silver underlying said sleeve which' comprises, fusing vitreous material about said copper sleeve and heating until the color of said wire in said vfused material changes to a straw or gold color. 1

l1. A method of sealing lead-in'wires having a copper sleeve and a conducting core which comprises, interposing a layer of silver between said sleeve and said core, fusing vitreous material about said sleeve and heating said material until the red color of said sleeve changes to a straw or gold color.

12. A method-of sealing lead-in wires hav# ing a coppersleeve and av nickel-steel core, which comprises, interposing a layer of silver between said sleeve and said core, protecting said sleewe with a borate, fusing vitreous material about said sleeve and heat- E ing said material until the red color on said sleeve changes to a straw orgold color.

13. An article of the type described which i comprises, a wall of vitreous material in the stem of a container 4or bulb, a nickel-steel wire entering said wall from the bulb side thereof, said wire containing approximately 42% by lweight of nickel, a copper ,wire en-v tering said wall from the opposite side thereof and having a socket into .whichthe -end of. said nickel-steel wire projects, an intervening layer of silver between and welded to the inner surface of said socket and the surface of said nickel-steel wire projecting thereinto, said vitreous. material being fused about the outer surface of said socket.

14. artic-le of the type 4described which comprises a wall of vitreous material in the stem of a container or bulb, a nickel steel Wire entering said wall from the bulb side thereof, a copper wire entering said wall from the opposite side thereof, and having steel wire is fitted and welded said-vitreous material being fused about the Vouter surface of said socket.

a socket into which the end of said nickel 15. An article of the type described which the inner surface of said socket and the surface of said nickel steel Wire projecting thereinto, said vitreous material being fused' 1G about the outer surface of said socket, the surface of said socket having a straw or gold color.

CLEMENS A LAISE.

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