US2697126A

US2697126A - Consumable electrode and procedure for forming and utilizing consumable electrodes

Info

Publication number: US2697126A
Application number: US228177A
Authority: US
Inventors: Schuyler A Herres
Original assignee: Allegheny Ludlum Steel Corp
Current assignee: Allegheny Ludlum Steel Corp
Priority date: 1951-05-25
Filing date: 1951-05-25
Publication date: 1954-12-14
Anticipated expiration: 1971-12-14

Description

Dec. 14, 1954 s. A. HERRES 2,697,126

CONSUMABLE ELECTRODE AND PROCEDURE FOR FORMING AND UTILIZING CONSUMABLE ELECTRODES Filed May 25, 1951 8 Sheets-Sheet l r 34b I 1 nm 4s 32 L D '1 I00 IN VEN TOR. Schuyler A. Herres HIS ATTORNEYS Dec. 14, 1954 s A HERRES 2,697,126

CONSUMABLE ELECTRO DE AND PROCEDURE FOR FORMING AND UTILIZING CONSUMABLE ELECTRODES 8 Sheets-Sheet 2 Filed May 25, 1951 Dec. 14, 1954 s. A. HERRES 2,697,126

CONSUMABLE ELECTRODE AND PROCEDURE FOR FORMING AND UTILIZING CONSUMABLE ELECTRODES 8 Sheds-Sheet 3 Filed May 25, 1951 QM Rf W? W. M y w I m m Y B J Y Fig.5

HIS ATTORNEYS Dec. 14, 1954 s A HERRES 2,697,126

CONSUMABLE ELECTRObE AND PROCEDURE FOR FORMING AND UTILIZING CONSUMABLE ELECTRODES Filed May 25, 1951 8 Sheets-Sheet 4 HHHHI I'III'I'I F, 8 INVENTOR. 36 a g Schuyler A. Her/es 7 WWW HIS ATTORNEYS S. A. HERRES Dec. 14, 1954 2,697,126 CONSUMABLE ELECTRODE AND PROCEDURE FOR FORMING AND UTILIZING CONSUMABLE ELECTRODES 8 Sheets-Sheet 5 Filed May 25, 1951 NM a; OW m 7 mw WW l w ll I I Ill! lf ll l| |l fil u 1 I J nl/ l l l l IIIWW T 'HN 1N! 'EN TOR. Schuyler A. Herres uu 9%: W

HIS ATTORNEYS Dec. 14, 1954 s A. HERRES 2,697,126

CONSUMABLE ELECTRObE AND PROCEDURE FOR FORMING AND UTILIZING CONSUMABLE ELECTRODES Filed May 25, 1951 8 Sheets-Sheet 6 Fig. I!

Fig. 19 Fig. 20

IN VENTOR. Schuyler A. Herres imi/fem MM HIS ATTORNEYS Dec. 14, 1954 s. A. HERRES 2,697,126

CONSUMABLE ELECTRODE AND PROCEDURE FOR FORMING AND UTILIZING CONSUMABLE ELECTRODES Filed May 25, 1951 8 Sheets-Sheet 7 g 2 I w if A K p ,4 INVENTOR.

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HIS ATTORNEYS Dec. 14, 1954 ERRES 2,697,126

S. A. H CONSUMABLE ELECTRODE AND PROCEDURE FOR FORMING AND UTILIZING CONSUMABLE ELECTRODES Filed May 25, 1951 8 Sheets-Sheet 8 IN VEN TOR. Schuyler A. Herres HIS ATTORNEYS feeding,

United States Patent CONSUMABLE ELECTRODE AND PROCEDURE FOR FORMING AND UTILIZING CONSUM- ABLE ELECTRODES Schuyler A. Herres, Albany County, N. Y., assignor to Allegheny Ludlum Steel Corporation, Brackenridge, Pa., a corporation of Pennsylvania Application May 25, 1951, Serial No. 228,177

Claims. (Cl. 1318) This invention relates to electrical apparatus and procedure for making and utilizing consumable electrodes and assembling, feeding, welding together, and applying energizing current to consumable electrode sticks.

One phase of my invention relates to the problem of introducing relatively large current values to a compacted metal electrode that is normally characterized by its somewhat poor conductivity. Another phase relates to the problem of effectively welding metal sticks together into an assembled group for providing a continuous electrode and one of suitable electrical conductivity. A further phase relates to the problem of feeding and assembling metal sticks that are to be formed into an integral electrode and in general, to the problem of preventing contamination of the electrode material during assembling, and welding it to form an integral electrode and during melting of the formed electrode.

This application is a continuation-in-part of my application, Serial No. 122,717, entitled Melting Titanium to Form ingots and filed October 21, 1949 now Patent Number 2,640,860, issued June 2, 1953.

In making ingots from a metal having the characteristics of titanium, difliculty has been encountered in transforming the metal from sponge or particle form into relatively pure metal ingot form. The difficulty is fur ther enhanced by the sensitivity of the metal to air, moisture, and other type of contamination.

In my above entitled copending application, I have disclosed apparatus for utilizing individual metal sticks that are press-formed from sponge, lump, or powder particles of metal, for feeding the sticks individually in a progressive series to assembling apparatus, for assembling the sticks in longitudinal progression, for welding the sticks into a continuous electrode, and for applying welding current to the electrode while feeding it into an arc-melting furnace.

Means is also disclosed for preventing contamination of the metal while the sticks are being processed as outlined.

The present invention deals generally with such a type of apparatus and particularly, to improved apparatus or procedure which makes possible a more efiicient, troublefree, and improved utilization of stick metal in forming integral electrodes, as well as an improved application of electrical, arc-forming energy thereto.

Metal of the type here involved may contain impurities that are incident to production, e. g. sponge metal is a product of reducing a titanium halide such as a tetrachloride with a molten reducing metal such as magnesium or sodium. The relative density of solid titanium to sponge metal is in the neighborhood of about 0.6. Zirconium is also of the same class of metal and its halide is reduced in a similar manner. The somewhat porous nature of the sponge metal as well as residual impurities therein tend to make it moisture absorbent. Although the electrical and heat conductivities of the solid metal are not too good, they are much worse in the stick metal. The latter is also somewhat brittle, has a tendency to crumble under pressure, and has a somewhat uneven surface even when compacted.

It has thus been an object of my invention to provide improved apparatus or procedure for converting crude metal of the type of titanium into metal ingots;

Another object has been to devise a better assembly of metal sticks to form a consumable electrode and to de- 2,697,126 Patented Dec. 14, 1954 vise apparatus to feed them into such an assembled relationship;

A further object has been to devise means for continuously forming an improved form of consumable electrode;

A still further object has been to provide a practical solution to the problem of utilizing sticks of somewhat crude titanium in work ingots;

These and many other objects of my invention will be apparent to those skilled in the art from the descriptive embodiments hereinafter set forth in view of the appended claims.

In the drawings, Figure 1 is a vertical sectional view in elevation through an apparatus arrangement employing my invention; this view somewhat diagrammatically indicates electrical and fluid-drive connections to the apparatus;

Figure 2 is an enlarged top plan view taken along the line IIH of Figure 1;

Figure 3 is an enlarged fragmental section of an upper portion of the apparatus of Figure 1; this figure illustrates an initial step in the operation of the feed mechanism, as illustrated by full lines, wherein a pair of sticks A and B are ready to be dropped from a chute into an empty compartment of a carrier and a pair of pneumatic feed plungers are in an initial position ready to advance a pair of sticks A and B from a diametrically opposite, filled compartment into an intermediate chamber having feed and assembly mechanism; the dot and dash lines of the plungers of this figure illustrate a third step wherein the plungers have fed the sticks A and B to the position represented by sticks A and B and are being withdrawn to the starting position represented by the full lines of this figure, at this time, the sticks A and B are now in their compartment (not shown);

Figure 1 illustrates an intermediate step in the operation of the apparatus, as it shows the feed plungers advancing the pair of sticks A and B from their compartment into the intermediate chamber and into a properly aligned and assembled relationship within such intermediate chamber, see the final position represented by the sticks A" and B of Figure 3;

Figure 4 is a further enlarged transverse section taken along the line 1VIV of Figure 3;

Figure 5 is an enlarged vertical section in elevation taken along the same side as Figure 1 and along the line VV of Figure 6; it illustrates the intermediate chamber and chain linkage for its mechanism;

Figure 6 is a vertical section on the same scale and is takersl at right angles to and along line VI-VI of Figure Figures 5 and 6 illustrate welding means and a motor driven linkage between various parts of mechanism which includes feed sprockets, feed rolls, and electrical contact rolls;

Figures 7, 8, 9, 10, 11, 12 and 13 are transverse sections, some of which are fragmental, taken respectively, along lines VII-VII, VIII-VIII, IX-IX, X-X, XI-XI, XII-XII, and XHI-XIII of Figures 5 and 6;

Figure 7A is an enlarged fragmental sectional detail taken along the line VIIAVIIA of Figure 7;

Figure 7B is a fragmental end view on the same scale $2 7A and is taken along the line VIIB-VIIB of Figure Figure 14 is a vertical fragmental section taken along the line XIVXIV of Figure 13;

Figure 15 is a greatly enlarged transverse section taken longitudinally along the line XVXV of Figure 9 and illustrating a welding electrode construction employed in my apparatus;

Figures 16 and 17 are cross-sectional views taken, respectively, along the lines XVI-XVI and XVII-XVII of Figure 15;

Figure 18 is a greatly enlarged vertical side sectional detail taken along the line XVIII-XVIII of Figure 1 and illustrating a sight window construction.

Figure 19 is an enlarged perspective view in elevation through a preferred form of electrode constructed in accordance with my invention;

Figure 20 is a view similar to Figure 19, but shows a pair of sticks in a unit stick relationship ready to be welded to adjacent stick units.

In carrying out my invention, see Figures 1 to 3, I employ a rotatable carrier, wheel, magazine, or conveyor 17 having a plurality of compartments 17a located as spokes of a wheel therein to receive metal stick pairs, such as A and B. The individual sticks are made by pressing-out hard, adhesive metal particles, such as obtained by crushing or pulverizing titanium or zirconium metal sponge. The pressing-out procedure is outlined in my above-entitled copending application. The carrier I7 is intermittently supplied with metal stick pairs by a fluid locked chute 11. A fluid motor or pressure feed mechanism 21 having a pair of pistons is superimposed on an enclosure 10 for the carrier 17 and is adapted to periodically feed or move out a pair of metal sticks A and B that are in one compartment, when that compartment is properly aligned with respect to a delivery opening 23a in the bottom of the enclosure 10 for the carrier.

The enclosure 10 for the carrier is superimposed on a cooling fluid jacketed, intermediate enclosure 36 which defines a hermetically sealed chamber for stick assembly, feeding, welding mechanism, and having an energy contact mechanism located therein. Such mechanism receives sticks A and B delivered from an aligned compartment of the carrier 17 as they are fed therefrom by the fluid motor 21, assembles the sticks, welds them together into an integral consumable electrode, supplies energizing current to the integral electrode, feeds the sticks and the electrode along the intermediate chamber, and feeds the electrode into an arc-melting furnace 160, see Figure 1.

The intermediate enclosure 36 is mounted on the furnace, is electrically insulated therefrom, and its hermetically sealed chamber is open thereto. Means is provided to condense impurities which are volatilized by the heat of the furnace 160 and to remove them adjacent the top of the furnace, while the lower end of the electrode is forming a melting arc with starting or molten metal in the furnace which is supplied with electric energy of opposite potential.

Means is also provided for sweeping out the intermediate chamber 36 of gaseous or more easily volatilized impurities. When one compartment of the carrier 17 has been emptied by the fluid motor 21, a drive motor 20 is provided for progressively advancing the next successive compartment of the carrier to an aligned feeding position and the operation is repeated. At least one weld bead is produced longitudinally along the electrode which joins axially abutting edges of the stick pairs, provides a more efficient electric current conducting path, and

avoids overheating of the electrode as well as of the mechanism in contact therewith while the electrode is being advanced into the furnace.

There is a definite problem involved in obtaining a suitable weld between compacted metal sticks of the type previously set forth. tain impurities, particularly halides, such as chloride, which are involved in reducing titanium (or zirconium) oxide to provide the metal. Such impurities will volatilize well below the melting point of the metal and a considerable area adjacent the actual joint being formed will be heated up sufliciently to cause such impurities to force their way out of the metal. For example, sodium chloride has a melting point of about 804 C. and magnesium chloride has a melting point of about 708 C., as compared to zirconium (1850 C.) and titanium (1795 C.). The volatilized impurities at the actual joint being melted have the maximum energy while the others have an energy force that decreases the greater distance they are from the joint. However, the flow velocity of the impurities evolving from the immediate F joint causes the other, lower energy, impurities to flow towards and concentrate at the immediate joint, at which high temperature point, they too increase their energy and thus, their velocity. This results in setting up a vacuum or suction action in the heated area of the porous sticks about the molten metal of the joint during the welding operation. As a result, relatively stagnate, ambient air impurities of the type of oxygen and nitrogen gas are sucked into this area and towards the underside of the diffusion zone and the underside of the molten weld metal. Since a metal of this type has the characteristic of pickup sensitiveness to such impurities when heated (even below its melting point), such impurities diffuse through and react with the metal of joint includ- In the first place, such sticks conill.)

ing the molten weld metal and the adjacent heated metal to produce an area of great brittleness and a poor bond.

It is highly essential to provide a good metal-to-metal bond between adjacent sticks and between the weld metal and body portions of the sticks. Such a bond is not only required to hold the sticks together as in integral whole, but also to provide the best possible conductivity between the weld metal and the body portions of these sticks. Good conductivity is needed to avoid local hot spots during the application of arc current thereto and to provide more efiicient current conduction from the point of contact to the point of arc melting of the integral electrode within a melting furnace. The integral electrode is relatively hard and brittle (refractory in nature) and the bond must thus be of a type that will not weaken the individual sticks of the electrode.

A good bond is thus essential in preventing a breaking off of the electrode as it is fed into the melting furnace. If it breaks off, at least the top portion of the ingot will be spoiled and in some cases, the whole ingot may be spoiled and must be discarded. That is, the broken-off portion will fall into the molten melt and at least spoil the upper end portion of the ingot, since the broken off electrode will not be completely melted down. I have seen a small diameter ingot whose entire central core axis was cracked and had shrunken away from its bounding wall; and I have seen other ingots (where a larger diameter electrode was used) whose upper end portion consisted of the irnbedded, broken-01f portion of the electrode. Due to the costliness of titanium and zirconium, such a loss of ingot metal must be avoided.

After evaluating the problem above presented, I have now found that it is not desirable to endeavor to prevent the evolution of volatilized impurities, and that the pickup action resulting therefrom can be controlled in such a manner as to avoid deleterious and insure beneficial eifects, all in such a manner as to prevent gaseous alloying and contaminating elements from entering the metal and to provide a proper form of bond that meets the various factors involved. In the first place, an electric, as contrasted to a torch type, of welding operation should be utilized. In the second place, an inert gas (argon, helium, etc.) ambient atmosphere should be maintained about the weld and about the adjacent heated surface area of the sticks during the full period when heat is present in them. That is, I have now found that such an atmosphere is essential, both when the welding arc is being applied and thereafter when the metal is being cooled down, if a poor or brittle bond is to be avoided. In the third place, the inert or non-contaminating gas should be maintained at a positive, slightly above-atmospheric pressure (e. g., 19 to 20 lbs/square inch) to exclude oxygen and nitrogen and insure that only inert gas is sucked up by the sticks. I find that the volatilized impurities, by reason of their greater energy, move towards the top of an enclosed, inert gas-containing chamber, where they can be readily removed. I have also now discovered that a vacuum ambient atmosphere is unsatisfactory as it promotes contaminating gas pickup and a return of the volatilized impurities to the metal.

I have now determined, contrary to what may be supposed, that the inert gas will not damage the bond by making it more porous, but aids in purging it of volatilized impurities. There is no pickup by or reaction with the metal and the inert gas is forced out of the weld metal as it solidifies. The porous nature of the stick body portions is beneficial in this connection and the freezing action of the weld metal sets up sufiicient positive pressure to overcome the slight positive pressure of the inert gas, since there is no chemical or solution bond between the inert gas and the metal. As a result, a non-porous, substantially pure metal, more ductile and conductive weld is obtained which does not weaken the brittle sticks, but actually strengthens them against breaking off when the integral electrode is fed into the arc melting furnace. Also, the use of stick units having offset end portions, the use of continuous and opposed weld beads, and the use of opposed welding electrodes energized by alternating current, all aid in effecting the best possible results.

As shown, I employ a series arc-melting method which automatically provides two opposed and longitudinally continuous welds beads a and b along the electrode, see Figure 19. Two alternating current arcs which are optween the enclosure secured thereto for rotation therewith occurs when one positely placed with respect to the work eliminate rectification effect, since the higher impedance of one arc is compensated by the lower impedance of the other. The total remains the same, although in every half cycle, the impedances of these arcs alternate between high and low. The joints thus produced are longer and cooler and produce half the current density in the integral electrode as a whole. The continuous bead method eliminates the need for welding synchronizing control, provides better current conduction in the bead than in the actual body of the sticks, and provides some preheat.

In the butt welding of successive sticks together, I have determined that there is a secondary difliculty in obtaining a perfect joint in that the joint may become heated to almost a white heat with some loss of strength. I-

solve this problem by providing a lap joint between sticks which may be obtained by feeding a pair of sticks in van assembled, staggered order along the welding arcs,

and by providing a pair of continuous and opposed weld beads along the sticks. Thus in effect, I employ a series of stick units, each of which is made from at least a pair of side-abutting sticks that are staggered to provide stepped or offset end portions for the unit. Each end portion interfits with a similar end portion of an adjacent stick unit that is made up in a like manner from at least a pair of side-abutting sticks, see Figures 19 and 20.

Referring particularly to Figures 1 to 4, inclusive, I provide an enclosure which hermetically seals OE and encloses the rotatable carrier, wheel, or magazine conveyor 17. Metal stick pairs A and B (see Figure 3) are introduced into the enclosure 10 through a chute 11 which projects upwardly therefrom and has a top opening therein that is closed off by a lid 12. The lid 12 has a hinge portion 12a pivotally mounted on portion 11a of the chute. A threaded pivot pin 14 is secured to extend upwardly from the chute 11 and within a bifurcated slot 12b (see Figure 2) of the lid and has a thumb nut 14a for securing the lid 12 closed in a tight relationship.

As also shown, the lid 12 has an annular gasket 12c inset therein to provide a fluid seal.

As disclosed in Figure 3, the pair of sticks A and B may be introduced into the chute 11 and aligned by its converging lower funnel portion 11b, so that they will drop into an aligned compartment 17a of the carrier 17. Immediately after the sticks A and B have been introduced, the lid 12 is closed and clamped down by the

means

14 and 14a to minimize loss of inert gas to the ambient atmosphere, since as will be later explained, a gas which is inert to the metal is continuously introduced from the chamber of the intermediate enclosure Y 36. This gas has a greater than atmospheric pressure and will exhaust from the chamber 10 when the lid 12 is open.

As shown particularly in Figures 1, 2 and 3, the carrier 17 has a plurality of rectangular compartments 17a therein which are adapted to be successively advanced into alignment with a delivery or feed opening 28a in a bottom closure member 28. The carrier 17 is secured or keyed to an axle shaft 18 which extends therethrough and is journaled adjacent its upper end by bearings a within a bearing mount portion 15 of the enclosure 10 and at its opposite or lower end by bearings 15b within the bottom closure plate or member 28 to which a flange 10a of the enclosure 10 is secured by bolt and nut assemblies 280. A gasket 13 provides a hermetic seal be- 10 and the bottom member 28. the shaft 18 has a gear sprocket 18a which is driven by a chain 19, a sprocket 20b, a fluid slip coupling 20a, and motor 20. The fluid slip coupling 20a rotates the wheel 17 at a relatively slow speed (about /a R. P. M. for sticks weighing about one pound each) until sticks A and B in one compartment 17a align with the feed opening 28a (see Figure 3) and plungers b and 26b start to feed them from the compartment 10 into the intermediate enclosure 36 (see Figure 1). At such time, the coupling 20a slips and permits the motor 20 to continue to rotate. The slippage of the coupling 20a also of the compartments 17a is aligned with the chute 11 and a pair of sticks A and B (see Figures The upper end of l and 3) are being dropped into the compartment.

The fluid motor 21 (see Figures 1 and 3) is provided to feed sticks A and B into the enclosure 36. The housing of this motor may be a casting having two cylindrical chambers 21a and 21b that are segregated by an I feed opening 28a to slidably intermediate partition 210, see Figure 4. A removable top head or end wall 22 of the motor 20 (see Figure 3) has fluid passageways 22a therein entrant to upper end portions of each of the cylinders 21a and 21b and connected by a nipple 22b to a flexible fluid supply line 34b. The head 22 is secured to the housing of the motor 21 by set screws 22c. A bottom head or end wall 23 is secured in a like manner to the housing of the motor 21 by set screws 23a. Ports 24a and 24b are entrant to bottom end portions of the cylinders 21a and 21b and have nipples 24a and 24'b connecting them to a fluid supply line 35b.

The fluid motor 21 is secured to an upwardly-offset mounting flange portion 16 of the enclosure 10 by bolts 23b which extend through the bottom head 23, see Figure 3. The cylinder 21a has a piston rod 25 operatively positioned therein and provided at its upper end with a piston head 25a for reciprocating movement therein. At its other end, the rod 25 has a stick pusher head or plunger 25b that is normally located within a chest or chamber 16a of the mounting flange portion 16. In a like manner, a piston rod 26 is operatively positioned in the cylinder 21b and has a piston head 26a at one end thereof for reciprocation therein. At its other end, the rod 26 has a stick pusher head or plunger 26b which as shown, is also adapted to be normally positioned within the chamber 16:: of the mounting flange portion 16. Glands 27 in the flange portion 16 provide a fluid seal for the

rods

25 and 26 which as shown, slidably extend through the bottom head 23 and the flange portion 16 into the chamber 16a.

When positive fluid pressure is applied through line 34b, see Figures 1 and 3, to the upper end of the motor 21, the pistons 25a and 26a will be forced downwardly, as indicated in Figure l, to push the sticks A and B out of an aligned compartment 17a into the intermediate enclosure 36. The flexibility of the fluid medium (pneumatic) permits each piston to move at a different rate, depending upon the resistance encountered by the pusher heads or

plungers

25b and 26b. When positive fluid pressure is applied through the line 35b to the lower end of the fluid motor 21, the plungers 25a and 26a will be moved to their initial or starting positions within the chest or chambers 16a, as indicated in Figure 3. During positive movement in one direction, the

opposite fluid line

34b or 35b serves as an exhaust line for the motor 21.

As shown in Figure l, the bottom closure member 28 serves also as a top closure member for the intermediate housing 36. A rectangular feed opening or bore 28a is provided through the closure member 28 which at its upper end is beveled or chamfered to facilitate the introduction of the sticks A and B. A depending rectangular guide frame 37 extends downwardly and its upper flange 37a (see Figure 3) is secured by bolts 37b to the member 28 about the feed opening 28a therein.

In addition, a transverse slot 28b (see Figure 3) is provided in the member 28 which projects beyond the receive a closure or slide plate member 29 which slides between it and the enclosure 10, see also Figure 2. Sealing gaskets 30 are inset within the member 28 and a portion 10b of the flange 10a of the enclosure 10 to seal off the slide plate member 29 and prevent fluid leakage thereabout. The slide plate member 29 may be employed to close off the feed opening 28a. For example, it may be employed when it is desired to by-pass stick delivery from one or more of the compartments 17a of the carrier 17, or when for some reason, the door 12 is open for a considerable length of time. The slide member 29 may be manually operated by an upwardly-projecting handle 29a.

Fluid for actuating the fluid motor 21 is provided by a positive flow supply line 34 and this line as well as a return or exhaust line 35 are connected through a dualacting, line-reversing valve 32 and

fluid lines

34a and 35a, to a dual-control, shut-off valve 31 and

lines

34b and 35b. The valve 31 is spring actuated to retain it closed to thereby shut off flow through both the

lines

34b and 35b. When its push arm 31a is manually pressed in or is normally pressed in by engagement with the outer end of the slide member 29 (when the latter is in its outer position of Figure 3), the spring will be compressed to open the valve 31 and to permit fluid flow between

lines

34a and 34b and

lines

35a and 35b.

ing engagement with the sticks A" and B". It will be noted that extension pieces 76 are welded to the plate members and position the side piece members that are secured thereon by bolts 77.

As shown in Figures 5, 6, 7, 7A and 7B, I show an upper sprocket 79 for guiding and adjusting the tension of a drive chain 80 which actuates the feed wheels 53 of station C, feed rolls of station E and contact rolls of station F. The sprocket 79 is secured on one end of an idler shaft 81 by a pin 82 and the shaft is journaled within a pair of sleeve bearings 81a. Each bearing 81a is eccentrically mounted (see Figure 7B) within a cylindrical cam block 83 which is secured to extend across between the pair of side plate members 45. A set screw 84 secures each cam block 83 in a properly adjusted relationship within each member 45. The shaft 81 and its bearings 81a can be adjusted eccentrically to provide a proper tension of the chain 80 by loosening the set screws 84 and rotating the cam 83 within the members 45. The opposite end of the idler shaft 81 is secured in position by a collar 85 and pin 85a.

As shown in Figures 5, 6 and 9, a second, lower positioned, chain guide sprocket 86 is mounted by a pin 86 on an idler shaft 87. Sleeve bearings 88 journal shaft 87 in members 45. A collar 89, secured on the shaft 87 by pin 89a, holds the shaft in position.

After the sticks have been assembled and fed from station C they are then welded together at station D into an integral electrode and thence, enter the pass of the feed roll station B, see Figures 1 and 5.

As shown in Figures 5, 6 and 10, I have provided a pair of driven feed rolls 90 and 90' at station E, each of which is secured on a drive shaft 91. Sleeve bearings 92 journal each shaft 91 in the side plate members 45. One end of each shaft has a sprocket 93 secured by a pin 93a thereon to receive the interleaving drive chain 80. One of the shafts 91 is the main drive shaft for actuating the chain 80 and its extending end is secured by a set bolt 93b to a sleeve extension shaft 94. The other end of the oilzer shaft 91 is held in position by a collar 91a and pin 9 As shown in Figure 10, the extension shaft 94 extends through a closure annulus 95 in the enclosure 36 and is journaled in a sealing plug-like sleeve bearing 96 that is secured within the closure annulus. The outer end portion of the extension shaft 94 is secured over an end of a stud shaft 97a of a speed reduction unit 97 by a set bolt 97b. A motor 98 is mounted on an extension platform 99 of the enclosure 36 to drive the unit 97.

Similar to the feed roll construction shown in Figure 8, one feed roll 90 of Figure 10 has a fixed position and the other is yieldably positioned by a yoke 90a. This yoke extends into a slotted-out portion in the members 45 and carries a slide pin 90b that receives a spiral tension spring 90d. A closure cap or housing 90e, is threaded to extend from an adjacent end member 46. And, a position limit 900 is sprung on a grooved end portion of the pin At station D, see Figure 1, as well as Figures 5, 6, 9 and 15 to 17, I provide a pair of opposed arc welding electrodes 100 which may be of a construction somewhat similar to the arc-melting electrodes of my copending application Serial No. 175,091 filed July 21, 1950, and entitled Arc Melting of Titanium to Form Ingots.

Each welding electrode 100 has a supporting or outer tube 101 of copper or stainless steel provided with a solid tip 102 of tungsten, copper or a suitable alloy secured to extend from the tube 101, and a cooling fluid inlet or inner, copper or stainless steel tube 103 extending therealong. A head 104 carries a cooling water outlet nipple 105 which at its inner end is fit into the outer tube 101 and at its outer end is knurled to receive a flexible rubber hose 106. An insulating and heat-resistant head plug 107 of glass, Bakelite, or other suitable plastic, for example, receives and supports an outer end portion of the inner tube 103 to which it is cemented. A rubber hose 108 is secured on an outwardly extending end 103a of the inner tube 103 to supply cooling Water thereto. It will thus appear that cooling fluid flows inwardly along the inner tube 103, out of its inner end (which has a spaced relationship with the tip 102), outwardly along the spacing defined by the

concentric tubes

101 and 103, and out through the nipple 105.

Energizing current is supplied to the electrode 100 by line 109 and a brazed-on connection 109a to the outer tube 101, see Figure 15.

A turnable adjustment sleeve 110 is locked at its outer end portion by a friction-set mounting pin 111, see Figures 15 and 16, to a lower end portion of the head 104. It will be noted that the head has an annular groove 104a about its periphery to receive the pin 111 and permit rotative movement of the sleeve part 110 about the head part 104. An inner end portion of the sleeve part 110 is threaded over a fixed position mounting sleeve part 112, so that when the part 110 is turned on the part 112 a suitable in and out adjustment may be effected of the head 104 and thus, of the position of the electrode tip 102.

A flexible, convoluted, stainless steel bellows 113 is secured by welding or brazing at its opposite ends between the head part 104 and the mounting sleeve part 112 to maintain a fluid sealed-off relationship between these parts and at the same time, to permit inward and outward movement of the head part 104 to adjust the gap formed between the tip 102 and the sticks to be welded.

The part 112 has a mounting flange 112a that carries an inset gasket 114 and that is secured to the enclosure 36 by a bolt and nut assembly 115. An insulating and heat-resistant sleeve 116 of a suitable material, such as Melamine glass (plastic), is cemented on the outer tube 101 and insulates it from the metal head and mounting

sleeve parts

104 and 112. One end portion of the sleeve 116 is slidably positioned within a longitudinal annular slot 112b and its movement therein is limited by stop pins 112c. The other end portion of the sleeve is cemented to the bore of the head part 104. As a result, the pins 112c control the maximum extended position of the tip 102 with respect to the electrode sticks A" and B" that are being welded together.

It will be noted that two opposed welding electrodes of like construction and mounting are employed at station D to continuously provide weld beads a and b of Figure 19 of the drawings and thereby provide a continuous, integral. consumable electrode. One of the welding electrodes 100 (see Figures 6 and 9) extends through an opening in the enclosure 36 that is defined by annulus 36h and the other electrode extends through the wall 36'. Both electrodes are mounted on the enclosure by boltedon closure mounts 112a and extend through slot openings 450 in the side plate members 45, see also Figure 5.

As shown in Figures 5 and 6, the pair of vertical end members 46 extend from locating pins 47a in the side members 45, vertically beyond such side members to swingably support and carrv the contact roll apparatus of station F, as shown in Figure 12. A support frame 120 is made up of two transversely-s aced pairs of vertical side members 121. Each member 121 is secured sidewise to an adjacent member 121 and endwise to an opposed member 121 of the same pair in a yieldable relationship by upper and lower sets of coil springs 142, see also Figures 5 and 6. The springs 142 are in tension and resist expansion of the spaced relationship between the members 121. Each end member 46 has an inwardly-projecting arm or bar portion 46b that projects into an open-end slot 121a in each member 121 of each pair of such members, see Figures 5, 6 and 12.

Each pair of side members 121 is yieldingly urged towards the electrode and thus, towards the other members 121, see Figures 5, 6 and 12, by the tension springs 142 at upper and lower ends of the frame 120. A pair of alternate bolts 143 is mounted on the end of each member 121 to secure opposite ends of the springs 142 in position.

As shown in Figures 5, 6 and 11, each of a pair of upper idler shafts 124 is journaled by sleeve bearings 125 to extend across each pair of side members 121 and is secured in position for rotation therein by collars 126 and pins 126a. A chain sprocket 127 is secured by a pin 127a on one end of each shaft 124 to mesh with and guide the drive chain 80. A single, lower idler shaft 124 has the same construction and mounting as the upper shafts, see Figures 5 and 6.

An upper and a lower pair of current supply, contact rolls 130 are provided to ride on opposite sides of the integral electrode and the mounting and construction of each is the same, see Figure 12. Each roll 130 of a highly conductive metal such as copper or brass, has an integral or press-fit on drive shaft 131 of the same material for rotation therewith. Each shaft 131 is journaled in highly conductive sleeve bearings 132 and is secured in position at one end by a collar 133 and pin 133a and at its other end by a chain sprocket 135. Each chain sprocket 135 of plastic or other insulating material is secured to the shaft 131 by a pin 135a and is actuated by the chain 89. For best results, the members 121, the collars 133, etc. are all of a highly conductive metal such as copper or its alloys. A pair of friction washers or discs 136 are carried by each shaft 131, are brazed to the side members 121, and are of an enlarged diameter to engage the full diameter of opposite ends of each contact roll 130 to increase the efficiency of current transfer between the side members 121 and the rolls. The discs 136 as well as the bearings 132 are of a highly conductive bearing material, such as Elkonite.

As shown in Figures 5 and 12, a current supply line 137 extends through a gland 138 of the enclosure 36 and is clamped by a highly conductivenut and bolt assembly 139 to opposite members of a fork or U-shaped bus-bar frame 141 Conductive bolts 141 secure ends of the fork frame to the side members 121 and thus, fully ener-' gize the frame .120. For better conduction, the springs 142 may be copper clad.

As shown in Figures 5, 6, l3 and 14, I provide two pairs of grooved-surface guide rolls 145 at station G which are located somewhat closely adjacent the furnace or crucible. A mounting frame 146 is secured to the enclosure 36 by stud bolts 147, insulating spacer sleeves 148, and nuts 147a. The frame 146 has spaced apart arm pairs 146:: which carry sleeve bearings 149 for stud shafts 154 within which the rolls 145 are journaled. Spring-like retaining rings 152 are positioned within grooves on end portions of each shaft to mount them in position.

One roll 1450f each pair is yieldingly held in engagement with the electrode. That is, a U-shaped yoke 153 directly carries one setof bearings 1520f one roll 145 and is slidab ly mounted in an end slot within the arms 146a to carry a pin 154 for mounting a tension spring 155 thereon. A housing cap 156 is secured to an upright piece 1'46b of the frame to enclose the spring 155 and slidably receive the pin 154. A retaining ring 151 on a grooved end of the pin 154 mounts the cap 156 on the pin and permits limiting the maximum inward sliding of the pm.

In Figure 19, I show a preferred utilization of consumable electrode sticks wherein the individual sticks are assembled in a staggered relationship and vertical weld beads a and b are formed by electrodes 100 along the assembly to provide an integral electrode at station D, see Figures 1 and 6. The welds a and b are employed to not only secure the sticks in groups, such as pairs and in longitudinal progression, but to provide longitudinal 'cur- I rent paths of higher conductivity.

I employ .alternating current for energizing the welding electrodes 100 and direct current for efiecting the arcmelting operation. The negative lead 137 (see Figure 1) of the motor generator set GM is connected to the roll assembly of station F, while the positive lead 137a is secured or brazed to a copper or bronze lug on the bottom of the crucible or furnace 160.

As shown particularly in -Figure l, the top closure member 161 of the crucible 160 is provided with a centrally located cone-shaped wall projection or batlle 161a to collect and direct vol'atilized impurities (such as residual materials or metals employed in reducing the titanium), upwardly and outwardly away from the electrode stick and through outlets 166 which are connected to a mercury trap 167. A gas such as argon that is inert to the value metal content (titanium) is introduced through a passageway 164 and a nipple 165 of the closure member 161. The closure member 151 has a cone-shaped, downward projection that serves as a heat b'a'flle between the furnace 160 and the intermediate enclosure 36.

Residual sodium or magnesium chloride present in sponge titanium (of the electrode) is vaporized by the arc of the furnace and is very corrosive in its characteristics. Such impurities are condensed, localized, and taken off adjacent the top of the furnace 160 by means of the construction of the closure member 161. The vapor pressure gradient is about zero and is at a maximum adjacent the arc within the furnace 160; this further helps to insure the desired result. Chloride control is important from the standpoint of the life of the construction, as well as the standpoint of its continuous service.

The continuous bead method employed eliminates the necessity for a welding synchronizing control. A conventional method of A. C. arc welding would require a large capacitator in the circuit to prevent a D. C. flow due to the rectification effect of the arc in providing a larger impedance to the how of welding current in one direction than in the other. The continuous energy required to melt sponge titanium is about 8/10 kilowatt hours per pound of titanium. Current in the order of about 1500 amperes and an open circuit voltage of about 100 volts is normally used. A high frequency starting signal may be provided for initiating the arc. 1 have found that with this power and energy requirement per pound, a feed rate of roughly one pound per minute can be obtained. Converted to a linear feed rate, this becomes about three inches per minute of double stick feed. Motor speed of up to about 15 times this rate may be employed and makes possible an arc control with a rapid response to errors in arc voltage. Much greater melting rates have been obtained with higher currents, e. g., a rate of 10 pounds per minute has been obtained with a melting electrode of about 10-inch square cross section, using an amperage of about 5000. Energy requirements of as low as .5 kilowatts per hour have been reached.

It has been determined that the copper roller contact method is practical from the standpoint of dependability of operation, ease of maintenance, and simplicity of design. Such a mechanism for current input to the electrode withstands high stresses mechanically, thermally, and electrically. A parallel arc input method also was investigated, but it was found that in such case, an arc picked one point of an electrode from which to emanate, and tended to select one welding electrode, instead of distributing equally from both electrodes.

The roller method gives favorable results from the standpoint of tests as to the amount of current input required to supply current for the melting arc, the amount of heat developed at the contact, from the standpoint of pitting and melting, and from the standpoint of a tendency for an electrode to stick or weld to the contact means. Only very slight sparking is entailed at the contacts.

The copper roller method of current input depends upon large machined surfaces with close tolerances for conduction between the supporting members of the rollers and the rollers themselvw'. The bare surface as well as the sides of the supporting members and rollers are 'used for current conduction.

Graphite grease is suitable for lubrication. Also, although contact rollers theoretically produce a line contact, this does not mean that the resistance of contact is infinite, as the large volume of copper backing up the line of contact, as the movement of such copper backing about its axis keeps the contact cool. Localized heating is avoided by employing an opposite pair of contact rolls and by distributing the current flow between upper and lower pairs of such rolls which are spring-loaded.

A single driving motor 98 has been employed for the sprockets and rolls and a chain and sprocket drive is utilized for positive rotation while permitting the maxi- Y mum utilization of an effective spring loading. Continuous automatic welding is effected on the electrode sticks which are then continuously fed as an integral electrode that is melted down into ingot form within the crucible; this further contributes to a coolness of contact roller contact.

It will be noted that the current (contact) input rolls at station F are positioned below the driven feed rolls and as close to the melting furnace as practical. The latter reduces the voltage drop between the lower end portion of the electrode which is forming the arc in the furnace and an upper portion thereof which is being energized.

When I utilize 1% inch square sticks in the manner shown in Figure 19, each about 15 inches long. I find that the roller method is the best method of current contact input. For an input current of about 500 to 1500 amperes (at about 100 volts), the voltage drop was about 1.45 to 4.20 across the contact and about l0 inches of titanium. The speed of the electrode was maintained at about two feet per minute for the above data.

The following table gives a comparison of the resistance of titanium in a 10 inch length rod at 1500 amperes:

Resistance f titanium Although I hereinafter claim the novel procedure of my invention, I reserve all my rights as to novel structure or apparatus herein disclosed.

What I claim is:

1. In making and utilizing a consumable longitudinally-extending electrode for which longitudinal sticks of adhesively compacted hard metal particles of the class of titanium and zirconium are utilized, and wherein the electrode is adapted to be energized with arc-melting current to melt it down in an arc-melting furnace, the method which also comprises, assembling the sticks in stick pairs, advancing the stick pairs in progression to a feeding position, feeding each stick of each pair in a side-by-side abutting relationship and at a different rate towards a welding position, forming a line of stick pairs of the thus-fed sticks in which the sticks of each pair have an endwise oifset relationship with each other and the pairs interlock endwise with each other, welding the sticks of each pair and the stick pairs of the line of stick pairs together without contaminating the metal of the sticks and forming an integral electrode, and applying arc-melting current to the electrode While introducing it into the furnace.

2. In making and utilizing a continuously-integral and longitudinally-extending consumable electrode for which a series of longitudinal somewhat brittle sticks of adhesively compacted hard metal particles of the class of titanium and zirconium are utilized, and wherein the integral electrode is to be energized with arc-melting current of one potential to melt it down in an arc-melting furnace of an opposite potential, the continuous method which comprises: feeding a series of the sticks progressively in staggered sets in a sidewise abutting relationship into and longitudinally along a non-contaminating atmospheric chamber; progressively moving successive staggered sets of the sticks into an endwise and sidewise abutting relationship with a before-advanced set; holding the sets in such relationship in close abutment, while advancing them as a longitudinal group, and while progressively welding longitudinally-extending abutting edges of the sticks of each set and of the abutting sets into an integral and longitudinally-axially extending electrode within the atmospheric chamber; and applying the arcmelting current of one potential to the thus-formed integral electrode in the atmospheric chamber and continuously feeding it as it is being formed in the abovedefined manner from the atmospheric chamber longitudinally-axially into the melting furnace.

In making and utilizing a consumable longitudinally-extending electrode for which longitudinal sticks of adhesively compacted hard metal particles of the class of titanium and zirconium are utilized, and wherein the electrode is adapted to be energized with arc-melting current to melt it down in an arc-melting furnace, the method which comprises: collecting a series of the sticks; feeding them individually and in succession into an abutting sideby-side paired, endwise-abutting and staggered relationship; holding the endwise-staggered pairs in a close and endwise abutting relationship, while feeding them, and while electrically welding them together along their adjacent edges into an integral electrode with a continuous longitudinal Weld bead in a non-contammatmg ambient atmosphere; and applying arc-melting current to the electrode while introducing it into the furnace.

4. In making and utilizing a consumable longitudinally-extending electrode for which longitudinal sticks of adhesively compacted hard metal particles of the class of titanium and zirconium are utilized, and wherein the electrode is adapted to be energized with arc-melting current to melt it down in an arc-melting furnace, the method which comprises collecting a series of the sticks;

feeding them individually and in succession into an abutting side-by-side paired, endwise-abutting and staggered relationship; holding the endwise-staggered pairs in close abutment in such relationship, while feeding them, while continuously electrically welding the stick pairs together into an integral electrode along their adjacent edges and along their opposite sides with continuous longitudinal weld beads of substantially pure and non-porous metal, and while continuing to feed the stick pairs in the defined relationship; etfecting the defined welding in a noncontaminating ambient atmosphere; and applying arcmelting curent to the electrode while introducing it into the furnace.

5. In making and utilizing a consumable longitudinallyextending electrode for which longitudinal sticks of adhesively compacted hard metal particles of the class of titanium and zirconium are utilized, and wherein the electrode is adapted to be energized with arc-melting current to melt it down in an arc-melting furnace, the method which comprises: progressively feeding the sticks into an endwise abutting relationship and as abutting pairs within an enclosed chamber, feeding each stick of each pair at a different rate than the other stick of the same pair until the sticks of each pair have the endwise offset relationship with respect to each other, feeding the offset pairs into an endwise abutting relationship with each other, maintaining a non-contaminating atmosphere within the enclosed chamber, continuing to feed the sticks while electrically welding the sticks and the stick pairs together in such defined relationships within the enclosed chamber and forming an integral electrode, applying arc-melting current to the integral electrode while feeding it into the furnace and progressively melting down its lower end portion, and progressively feeding and welding on additional sticks within the enclosed chamber to an upper end portion of the electrode as the melting down operation progresses on its lower end portion.

6. In making and utilizing a continuously integral and longitudinally-extending consumable electrode for which a series of longitudinal somewhat brittle sticks of adhesively compacted hard metal particles of the class of titanium and zirconium are utilized, and wherein the integral electrode is to be energized with an arc-melting current to melt it down from its forward end portion in an arc-melting furnace, the continuous method which comprises: feeding a series of the sticks and progressively assembling them in an endwise staggered and longitudinally-axially extending relationship; continuing to feed the series of sticks in their assembled relationship while progressively electrically welding their longitudinal abutting edges together in the defined assembled relationship and forming an integral and longitudinally-axially extending electrode; continuously advancing the electrode longitudinally-axially into the melting furnace while progressively melting the electrode down from its forward end portion within the furnace; feeding additional sticks in series progression into and assembling them in an endwise staggered and longitudinally-axially extending relationship with respect to a rear end portion of the previously formed integral electrode and with respect to each other; progressively electrically welding longitudinal abutting edges of the additional sticks together and to the welded longitudinal edges of the rear end portion of the previously formed electrode in their defined assembled relationship; progressively adding the additional sticks to the rear end portion of the integral electrode in the defined manner while its forward end portion is being melted down in the furnace; maintaining a non-contaminating ambient gaseous atmosphere about the sticks and the integral electrode formed therefrom while welding the sticks and forming the integral electrode, while Welding the additional sticks to the rear end portion of the integral electrode in the defined manner, and while feeding the resultant heat-up electrode into the furnace; and driving off gaseous and more readily volatilizable impurities from the sticks and the integral electrode within such non-contaminating ambient atmosphere.

7. In making and utilizing an integral and longitudinally-extending consumable electrode for which a series of longitudinally-extending somewhat brittle sticks of adhesively compacted hard metal particles of the class of titanium and zirconium are utilized, and wherein the electrode is adapted to be energized with arc-melting current to melt it down in an arc-melting furnace, the

method which comprises: feeding a series of sticks progressively into and assembling them in an endwise abutting and longitudinally-axially extending and in a transversely side-by-side supported assembled relationship into and along a non-contaminating atmospheric chamber, progressively moving successive sticks into the previouslydefined relationship with the first-mentioned series and with each other; holding the sticks in such defined relationship in close abutment while advancing them as a longitudinal group and while progressively welding longitudinally-extending abutting edges of the sticks together and forming an integrally-supported and longitudinallyaxially extending electrode within the atmospheric chamber; andtapplying arc-melting current to a forward end portion of the thus-formed integral electrode while continuously feeding it as it is being formed in the above defined manner along the chamber and into the melting furnace.

8. In making and utilizing a longitudinally extending consumable electrode for which somewhat brittle longitudinal sticks of adhesively compacted hard metal particles of the class of titanium and zirconium are utilized, and wherein the electrode is adapted to be energized with arc-melting current to progressively melt down its forward end portion in an arc-melting furnace, the method which comprises: progressively assembling a series of sticks in a mutually side-supporting relationship and forming a longitudinal line of sticks while feeding the sticks along an enclosed chamber within which a noncontaminating atmosphere is maintained, progressively welding successive longitudinally-extending edges of the sticks of the line together in a self-supporting manner and with a continuous weld along at least one longitudinal side of the sticks and forming a continuous integral electrode, and continuing to build up the electrode in the defined manner while feeding a forward end portion of 1 6 the electrode into the furnace and progressively melting it down within the furnace.

9. In making and utilizing a consumable electrode as defined in claim 8, the method which comprises, feeding the series of sticks into the defined assembled relationship at a different rate than the feed of the electrode into the furnace.

10. A longitudinally-extending integral consumable electrode composed of a series of somewhat brittle longitudinal sticks of adhes'ively compacted hard-metal particles of the class of titanium and zirconium, said sticks being positioned in a longitudinally staggered .and sideby-side abutting relationship, and continuous longitudinal weld beads securing longitudinally-extending abutting edges of the sticks together in longitudinal progression along the electrode.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 473,393 Heroult Apr. 19, 1892 1,043,481 Taylor Nov. 5, 1912 1,313,125 Shoeld Aug. 12, 1919 2,083,309 Applegate June 8, 1937 2,541,764 Herres .et a1. Feb. 13, 1951 2,564,337 Maddex Aug. 14, 1951 2,640,860 Herres June 2, 1953 OTHER REFERENCES Parke et a1: Metals Technology, Technical Publication No. 2052 v. 13, No. 6, September 1946 (12 pp.).

Project Rand: R-131 March 15, 1949, Battelle Memorial Institute (pp. 52-58) Herres et al.: Steel, May 2, 1949, pp. 82-86 and 135.

Claims

10. A LONGITUDINALLY-EXTENDING INTEGRAL CONSUMABLE ELECTRODE COMPOSED OF A SERIES OF SOMEWHAT BRITTLE LONGITUDINAL STICKS OF ADHESIVELY COMPACTED HARD-METAL PARTICLES OF THE CLASS OF TITANIUM AND ZIRCONIUM, SAID STICKS BEING POSITIONED IN A LONGITUDINALLY STAGGERED AND SIDEBY-SIDE ABUTTING RELATIONSHIP, AND CONTINUOUS LONGITUDINAL WELD BEADS SECURING LONGITUDINALLY-EXTENDING ABUTTING EDGES OF THE STICKS TOGETHER IN LONGITUDINAL PROCESSION ALONG THE ELECTRODE.