USRE16012E - Method of electric-arc welding - Google Patents

Description

Mar. 3. 1925. 4

C. J. HOLSLAG METHOD OF ELECTRIC ARC WELDING, CUTTING, AND REPAIRING 2 Shets-Sheet 1' Original Filed April 50 1918 Z M! W 0 a Z 3 3 24 a a m 4 a i if t 39 5/ l/VVE/VTUR (Wade Jflobhg B) @661) zrf/ip Mar. 3. 19 25. 16,012

' c. J. HOLSLAG METHOD OF ELECTRIC ARC WELDING, CUTTING, AND REPAIRING v Original Filed April :50. 1918 2 Sheets-Sheet 2 L 5 :9 Jo

XX X X X CMFRENI' {serum/m1 Coaa. WT

A TTORNEY formers, Serial No. 211,831, filed Reissued Mar. 3, 1925.

UNITED. STATES PATENT OFFICE.

CLAUDE J". IHIOLSLAG, OF SOUTH ORANGE, NEW JERSEY, ASSIGNOR TO ELECTRIC ARC CUTTING & WELDING COMPANY, OF NEWARK, NEWJERSEY,

METHOD OF ELECTRIC-ARC WELDING, CUTTING, AND REPAIRING.

Original 1T0. 1,305,362, dated June 3, 1919, Serial No. 231,681, filed April 30, 1918. Application for reissue filed October 13, 1919.

To all whom it may concern:

Be it known that I, CLAUDE J. HOLSLAG, a citizen of the United States, residing at SoutlPOrange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Methods of Electric-Arc Welding, Cutting, and Repairing, of which the following is a specification.

Broadly stated, the method of metallic arc welding, cutting and repairing consists in providing for one electrode the material to be welded, cut or repaired and for the V U I hvered directly from the terminals of the other electrode the welding, cuttin or repairing material, striking an arc etween these said electrodes and maintaining this are stable so that the work may be performed in a rapid and satisfactory manner.

In my application for an alternating currentwelding transformer, Serial No. 198,- 352, filed October 251, 1917, now Patent 1,305,360 issued June 3, 191-9 and my application for alternating current Welding trans- January 14. 1918, now Patent 1,305,361 issued June- 3, 1919 and particularly in the last men' tioned application, I-have shown and described transformers to be u sed in carryingv out my method of welding or repairing by means of alternating current. Heretofore it has been the general practice to use direct current, the same being obtained when the source of power was alternating, by means of a motor-generator set or an arc rectifier and reactances. The reason for the almost universal use of direct current for metallic arc welding, cutting and repairing is due to the difficult of maintaining with alternating current-c1 stable are which is highly essential for eflicient electric welding.

Numerous attempts have been made by others to do welding, cutting and repairing by means of alternatin current but these attempts have resulted 1n failure or in the very limited use of a relatively high initial voltage which is cut down, and an attempt .m'adcat regulation, by means of resistances and inductances, all of which is exceedingly wasteful in power consumption, and fur:

therniore limited to the use of slag covered.

electrodes in an attempt to confine the gases Serial No. 330,485.

former or a combination of transformers which I refer to broadly herein as a transforming device 111 which the current used for welding, cutting and repairing is de transforming device at the voltage of the arc, and which will weld with either bare or covered electrodes, andso faras I. am aware, I am the first to produce a success ful apparatus or method of metallic arc welding, cutting and repairing, whether the a aratus delivers alternatin current are voltage" or direct current, in which the 1s delivered at the terminals of the machine. It is generally understood that with direct current the positive electrode develops greater heat than the negative electrode which is very objectionable and I have found after a long study of this subject that the alternating or reciprocating arc possesses many advantageous features over the direct current are and gaseous flames, such as o-xy-acetylene, in that thealternating or reciprocating, arc has afar greater penetrating power and more uniform heating effect with the same amount of energy consumed at the arc and that, due to the greater agitation of the molten metal a more homogeneous weld is made. In fact, after a. weld is made by my method of welding. the material will break elsewhere rather than at the weld when put under stress.

After 'a long study and many tests, I have I found First: Thatthe welding transformer or transforming device should be adapted to deliver a constant rate of heat. energy at til . or methods.

shall be substantially constant over a given ran e.

-Scond: The control of the heat energy should be automatic within the machine itself and should coverwide limits to suit the various classes of work and various sizes and classes of electrodes. L

Third: That the transformer or transforming device should have a quick acting puncture or guardian voltage to reduce the tendency to open circuit which would be caused by the presence of dirt, oil, slag, etc., in the metals to be' welded, cut or repaired; that is to say, where a slag covered electrode is used, or dirt or oil be on the metal or ma terial to be weldedor'repaired and this foreign matter: gets in the way, tending to put out the arc or openthe circuit, this puncture or guardian voltage should be present I to actinstantaneously to break through or push out of the way the foreign matter.

Fourth: That the puncture or guardian voltage should be readily adjustable for anyparticular piece of work at hand, such adjustment being made by varying the voltage taps on both the primary, and secondary windings as well as a quick adjust ment either manual or automatic of the flux paths through both primary and secondary windings.

Fifth: That the transformer or transforming device should be capable. offquick current or voltage adjustment to apply. the

welding or repair metal in any one of the following ways: burnt in or penetrated, laid' on or padded, smoothed over or for finishing and to act in any positi n, horizontal, vertical or overhead.

Sixth: That the transformer or transforming device, while possessing all of the above mentioned features and characteristics and others which will occur to an ex.- pert welder, should be small and compact soas to'be readily portable and have an electrical efficiency far greater than'welding apparatus now onthe market and have a greater speed in welding, that is to say, ounds of material deposited per hour to e greater than in present known machines The principal objectptherefore, of my invention is to provide a method of metallic arc welding, cutting and repairing which accomplishes all of the above features set forth,, as well as others which will be apparent to one skilled in' the art.

In order to illustrate my method of metallic arc welding, cutting and repairing and,

to make the-same clearly understood within the scope of this application, I have 'in-. corporated herein the drawings of my two previous applications,.hereinbefore referred A to, and in addition I have shown the characteristics of one of my transformerspr transforming device from which the comstantially twice mercial success of my :invention will be application will be used herein. 4

In the drawings, Figure 1 is a perspec tive view of one form of transforming device.

Figure 2 is a vertical sectional view, particularly showing the meansfor' adjusting the position of the flux diverter. I Figure 3 is a diagrammatic view, showing the disposition of the windings employed.

- Figure 4 illustrates diagrammatically atransforming device consisting of two transformers adapted to be connected to a two phase circuit.

Figure 5 illustrates diagrammatically a transforming device consisting of' two transformers adapted to be connected. to -a three phase circuit with the well known Scott connection, three to two phase and two phase to single phase, as in Figure 4. Figure 6 illustrates diagrammatically a transforming device consisting of two transformers adapted to be connected in open delta three phase circuit.

Figure 7 illustrates diagrammatically a transforming device consisting of two trans formers adapted to be connected'toa three phase pow-er circuit with one phase reversed so that the total secondary voltage is subthe voltage of any one transformer. i

Figure 8 is a reproduction of an oscillograph record showing the secondary current and secondary or are voltage from a machine similar to that ures 1, 2 and 3. r

'Figure 9 is a reproduction of an oscillograph record of the E. M. F. generated in the Ifrain and auxiliary secondary coils but with .the different oscillographrsensitive' ness than the curve in Figure 8.

Figure 10 is a reproductlon of an. oscillograph record showing the E. of

suitably connected through its terminals 4% with a source of alternating, pulsating or varying current of electricity. Arranged on another leg 6 of the core, remote from v the leg 2, 1s a portion 5 of a secondary WlIld ing, which portion I term the secondary auxiliary coil, the functions of which will to the details, wherein v I illustrated in F igbe later pointed out. A second portion .7 of the secondary winding is arranged on the leg 2 and the convplut-ions thereof are pre-f- .erably intimately associated or co-mingled with those of the primary winding. This ,portion of the secondary winding, Iterm the main secondary coil. 1 have found in practice that a close association of the main secondary coil with the primary winding is highly desirable, due to the -.magnetic leakage between the primary winding and the main secondary coil being reduced, to

cut or repaired;

, provided at one or more intermediate points with taps which, bysuitable connections, permit of the use of the Whole of each winding or of any desired portion thereof, in

'windings of the coil.

order that the best conditions maybe obtained to meet the requirements for welding, cutting or repairing different metals, either when clean or when having dirt, grease, oil, slag or the like on the parts to be operated upon. To this end the primary coil 3 is providcd'with tabs 12 by the use of which, such connection may be made with the source of current as to increase or diminsh the number of the effective The auxiliary secondary coil-5 has in it the taps 13, and the main secondary coil is provided with taps 14 thereby allowing variations in the num ber of turns of each of said coils whereby the voltage relation of one coil to the other and to the work may be quickly adjusted. Iriterposed' between the legs of the core is a fluxdiverter 1 5, which, in the form of transformingdevice shown, is composed of a laminated bar of a length slightly less than the distance between the transverse portions 21 of the core. In order that the 5Q flux diverter may be moved to any desired are connected to. the bars 17 'in a mann' r to allow of the screw being freely rotated and to be retained against longitudinal movement. Attached to one end of the screw position relative te thetransverse portions of the core to wholly :or partially closethe magnetic circuit, or to be moved out of line with such portions and to v-have .open deltaconn'ection to a three phase c1r,

no effect ons'uch circuit, it is mounted on a frame consisting of tlie arms 16 secured to'the transvers'e'portions of the core and connecting bars 17 secured to the outer ends .of the arms. uThe flu'xfldiverter has in it anopening containing a nut 18 for re'ceivg, ing the screw 19.. The ends'of the nor w is a handle 20 for convenience intu'rning the screw,'and by the use of which the flux diverter may quickly be moved to'focc'upy' the desired position relative to the core. Secured to each end ofthe bar15' is an outsprings bear upon .the inner faces of the .7 Wardly extending brass spring 11, which" respective transverse portions of the core.

The frictional contact betweerrthe screw and the nut 18 and that of the springs on the core are suflicient to retain the flux diverter in any position in which it may be placed against movement by reason of attraction exerted upon it when currents pass through the coils on the core. It is ,apparent that these details of mechanical construction may be variedbver wide limits; for example, when high-initial starting voltage and current is required with immediate sinlring to e. steady lower working, value, the diverter may be arrangedto work automatically by being mounted onsuitable guides and controlled by the magnetic flux acting on the diverber against a Spring and dash pot.

In the arrangementshown in Figure 4, two transformers22 and 23 are. illustrated, similar to that shown in Figure 3, but ares f ranged to be'connected' to a two phase circuit; that is, the primary 12 of trans-' former 22 is adapted to have its terminals 44 connected to one phase and the trans former 23 is adaptedto haveits terminals 49% connected to the other phase. Each primary mayhave one or more taps 12 or 12, same as in Figure 3. The secondaries may also have any suitable number of taps. It will beunderstood that instead of two independent transformers as shown, they] may be combined into an integral structure.

are illustrated somewhat similar to that in Figure't" but-the primary windings have terminalsl i'which are adapted to be concuit, the arrangement giving a three phase- In Figure 5, two transformers 24 and 25 i 'nected to a three phase power supply cirto two phase to :single phase, the secondary coils all being connected in series with suitable taps as descr bed in previous arrangements.

In Figure 6,: two transformers 26 and 27 are'illustrated'with their primary terminals 4 adapted to be connectedv in, an

cuit.

In Figure three transformers 28," 2Q. and, SQ'are illustrated having the terminals Jarrangement, I that the secondary voltage istwice Ithejdltage in an one of thej transformers. This method of connecting transformers'for metallic arc Welding, I believe to be new and unique.

' In considering the method of operationof the special transformers or transforming devices hcreinabove described,I have'made oscillograph records which I have reproduced in the drawings as Figures 8, 9 and .between the electrode 8 and the work 9.

The lower curve in Figure-10 is the E. M. F. of the auxiliary coil on open circuit. It is seen that these curves are practically alike and are in phase, however, ust as soon as the arc was struck between the welding electrode and the material to be welded the E. M. F. curveof the auxiliary secondary coil under the welding condition imposed, immediately shifted its phase position and changed its character as shown by the lower curve of Figure 9. The'E. LI. F. curve of the main secondary coil which is interlinked with theprimary winding retained its shape and osition. The shifting under load of the M. F. of the auxiliary secondary coil both in phase and character to an extent depending on the load has in itself a regulating effect and is in part explained by the fact that the auxiliary secondary coil is remote from the primary and'all of the flux generated by the primary does not pass through the remote portion of the secondary on account of normal flux leakage and the leakage due to the diverter which was part way in when the oscillograph records were made. That leg of the core surrounded by the auxiliary secondary coil not being mag netized to the extent that the leg surrounded by the primary and main secondary coil, is highly responsive to flux changes and heme will generate a voltage that responds immediately to conditions of the arc andwhich I term a puncture oi'guardian voltage which isrsuperimposed on the main coil voltage to give a, resultant or effective voltage deliv- I Cl ered by the secondary winding as indicated by the lower curve of Figure B, the curve being marked Total secondary voltage" while the. current in the secondar winding is shown byithe upper curve in igure 8. An

inspection of, the total voltage curve shows that the voltage across the are changes ra idly from a positive to a negative maximi m and vice versa. That is, to say, at the time when the resultant current in its cycle is passing through zero the voltage across the are is at a maximum value which remains substantially constant under constant conditions of the arc, or is at the point of shift ing almost instantaneously to a maximum value in "the opposite direction. The rogue lating features of the auxiliary secondary coil are indicated by the peaks markedBl to 36 inclusive on the total secondary woltage I curve wherein the voltage tends to rise across the are as the current passes through zero, but the building up of the current to its maximum value quickly suppresses the rise in voltage and a substantially constant voltage is thereby maintained so long as the physical conditions remain constant, but

particular attention is called to point 37 in this curve as it shows further the regulating or guardian effect of the auxiliary secondary coil to supply instantaneously the additional voltage required to penetrate the oil, slag, dirt and other foreign material which may be present at the weld.

It will be apparent by an examination of these curves and a careful study of the subjert matter of this specification why ordinary transformers cannot be used for alternating current metallic arc welding, the trouble being in such transformers that the effective voltage across the arc does not i change from one maximum to the other with sufficient rapidity to stabilize or-maintain the -arc. Furthermore due to the reactions in my transformers the current in the pri-. mary does not rise to. a detrimental value when :the electrodes are short circuitedas they are when the arc. is struck, as it does in anordinary power transformer. It is of in- .terest to note at this point that an alternat- 1ng current voltmeter connected across the terminals of the secondary coils at the time when these oscillograph records L were, ob-- tained showed the following readings Figure 10 E. M. F. of main secondary coil 57 volts; E. M. F. of auxiliary secondary coil 52 volts. Figure 9 E. LI. F. of main secondary coil, 52 volts; E. M. F. of auxiliary secondary coil, 47 volts, while the total secondary voltage of Figure 8 shown by the voltmeter was from 26 to 29. These readings of themselves indicate a phase displacement of the voltages generated by the two coils and the curves show graphically what takes place under one set of conditions. It is also to be noted that the secondary current and efi'ective voltage; for the conditions imposed at the'time which was in welding two pieces of steel together with a' certain size electrode, are substantially in .phase givof volts and amperes.

the "use of taps in the primary coil,

ltja

and of those. in the different parts of the secondary coil, and the adjustment of the flux diverter, conditions can quickly be arrived at to permit the use of an alternating electric current for cutting, welding or repairing steel, cast iron, copper, aluminum and other metals heretofore difficult or impossible of commercial welding or repairing when using either flux, bare or slag covered electrodes. When by the means described the best general average electrical conditions for welding, cutting or repairing are arrived at, such conditions are 1utomatically maintained, as the voltage of the secondary due primarily to the auxiliary secondary coil, varies instantaneously to counteract increased drop, presence of dirt, oil, slag, etc., thus holding the heating power at the arc substantially constant over a given range during the operation of welding, cutting or repairing. This secondary voltage can be varied to accommodate two or more arcs in series and when so adjusted it is advisable to use a non-inductiveresistance across the secondary, as shown in dotted lines at 38, Figure 3; to take the back E. M. F. or kick voltage when the arcis ruptured; or a third leg of small cross section may be provided on the transformer remote from the other two legs and having a suitable number of secondary turns wound thereon in reverse direction to the other two legs so that little or no opposition to the current is offered when welding is going on but on the instant of opening the circuit at either are this third leg develops a voltage in value and phase sufiicient to hold down the total kick voltage to a safe limit.

After the proper adjustment of the'transformer parts, as above described, an increased current passing through the primary coil, in consequence of loweringthe resistance in the secondary circuit, will result in the increase of the magnetism of that part of the core whichis in the primary coil.

-The consequent increase in the current in that part of the secondary coil located remote from the primary will result in an increased production by it of magnetic lines to oppose those emanating from that part of the core on whichthe primary is located, thus aiding in limiting and regulating the secondary current and the voltage. The additional magnetism produced by the increase in current in the secondary circuit, while; having a desirable effect in tending to stabilize the primary current, does not act with suflicient force to meet all the requirements I a in a circuit when a manually-held weldingor cutting tool is included It is for the purpose of obtaining. tlie necessary force and. certainty of action on the primary that I comingle a part of. the secondary with it. When there is a tendency to induce a current in excess of that found to be best adapted for the work being done in the secondary circuit, that portion of the secondary coil which is interwound with the primary coil develops additional magnetic lines of force which act in opposition to the flow of the primary CUI'I'QD'L, retarding it sufficiently to establish the conditions first determined upon as suited for the work.

As a result of the automatic control of the current both in the primar and secondary by the means described, by which the volts and amperes compensate each other, that is if the operator lengthens the arc slightly, the volts go up and the current drops or vice versa, in a manner to holdthe heat energy at the are constant, for as the arc is lengthened greater voltage is required to hold it and the longer the arc, the more heat is required to hold the temperature of the molten metal constant. In fact my transforming device is so arranged with respect to the arrangement of its primary and secondary coils, and

-magnetic circuits, that for certain classes of welding work,for example very thin material, in which approximately a constant current is desirable, a drooping characteristic can be obtained; while for other work, such as carbon are cutting wherein a constant voltage is desirable, a holding-up characteristic approximating constant voltage, can be obtained by using the main secondary winding alone or a small part of the auxiliary secondary, in which latter case the flux diverter is set to have substantially no effect. In between these two extremes the proper selection of taps on the different coils, aided by the fiumdiverter, will give for general welding purposes regulation of the voltage and current such that substantially a constant rate of heat is obtained at the are over a given range even when the electrode is automatically, semi-automatically or manually held or fed and the secondary can be connected directly to the work and to a welding, cutting or repairing tool, avoiding the interposition of resistances or impedances *in the secondary circuit and the resulting large waste of power and bare or covered electrodes can be used and the heat; delivered to the arc is thus maintained substaiitially constant, within ordinary limits,

irrespective of the lengthening or shortening of the are by reason of the movement of the welding or repair electrode resulting from the fact that the same is manually held or due to other physical conditions.

While I have shown and described in detail a preferred form of my invention and. the method in which the same operates in practice, I do not wish to be limited to the details of construction and other methods of application except as set forth in the appended vclaims.

Having thus described my invention what I claim is 1. The method of welding, cutting'and repairing by electriccurrent wherein the metal to be welded, cut or, repaired conor repairing.

2. The method of cutting, weldingand repalring by alternating current, wherein the material to be cut, welded or repaired constitutes an electrode and the cutting, -=welding or repairing material constitutes an op posite electrode, consistingin transforming directly the alternating current and passingit tosaid electrodes so that the E. M. F. across the are produced by the separation'of said electrodes is the resultant of 'at least two voltages, one of which is quicker than the other component or components to respond to changes in the cutting, welding 0r repairing conditions.

3. The method of electric are cutting,

welding and repairing by alternating current energy, which consists in supplying alternating current energy, transforming sa1d alternating current energy directly into another form in which the voltage factoris a composite one, and operating a movable electrode in close proximity to the material to be cut, welded or repaired, said material constituting an opposite electrode, and pass ing the transformed energy through said. electrodes, whereby a persistent are is formed and the heat thereof maintained substantially constant by reason of said composite voltagefactor'. C

4. The method of cutting, weld1ng and repairing by alternating current, wherein the material to be cut, welded or repaired constitutes an electrede (and the cuttmg, welding or repairing material constitutes an opposite electrode, consisting in transform the a ternating current sothat in directly b tages is obtained, then a plurality aof v0 shifting the phase relation of these voltages by striking an arc between said electrodes whereby a resultant E- M. :F. 15 obtalned -across thesaid arc and sustaining said are by saidresultant E. M. F. within ordinary limits during the cutting, welding or repairing operations. i I

5. The method of welding, cutting-and repairing by electric current wherein the metal to.be Welded, cut or repaired constitutes an electrode and the welding, cutting or repair ing. metal constitutes anopp'osite electrode, consistin in directly transforming an alternating current and producing E. M. F.sof different characteristics so that when the are is struck by passing the current through said electrodes an effective 13 M. F. is obtained which reciprocates across the arc with sudden change between substantial maxima of difi'erent polarity.

6. The method of welding, cutting and repairing by electric current wherein the metal to be welded, cut or repaired constitutes an electrode and the welding, cutting or repairing metal constitutes an opposite electrode, consisting in directly transforming an alternating current and producing voltages of diiierent characteristics so that after the arc has been strucir by passing the transformer current through said electrodes one of these voltages acts as a puncture voltage for the arc whereby the same is maintained stable in the presence of dirt, oil, slag, etc., described. g

7-. The method of electric are; cutting, welding andrepairing by alternating current, which consists in supplying alternating current having a certain E. M. F. wave form, converting said alternating current directly- .into another alternating current and controlling said converted current by l an E. l\l.-F.'having a wave form different from the first and which will sustain an alternating are between the material tobe cut ,,welded or repaired, and amovable electrode. i

8. The method of electric arc cutting, welding and repairing by alternating current which consists in supplying alternating current having a certain E. M. F.:' wave forin converting said alternating current 1 directly into; another alternating current and controlling said converted current by an E. M. F. having a wave form different from' the first and which will sustain an alternating are between the material to be cut, welded or repaired, and a movable electrode, and absorbing the back M. F. or rich voltageif the arc is ruptured, and limiting the puncture i 'oltage generated at; this time 9. The method of welding, cutting and repairing by electric current wherein the metal to be welded, cut or repaired constitutes an electrode and the welding, cutting or repairing metal constitutes an opposite 1 electrode, consisting intransforming directly an alternating current. of one kind into a second current, passing said second current through said electrodes, saidsecond currenthaving a working E. M. F. estab- 1 lished when the current is passed through theelectrodes, and equal to that across'the.

arc.

10. An alternating current system for electric, are cutting, welding and repairing 1 comprising an are cutting, welding or repairing circuit in which the material to be cut, welded or repaired constitutes one electrode and the cutting, welding or repairing material constitutes the. opposite electrode, 1

a transformer for supplying current-directlyto said circuit having preferably a closed circuit core constructed to provide a plurality of flux paths, and primary andsecondary windings arranged on said core so as to control the flux distribution in said flux paths according to the electrical requirements of said welding circuit.

11. An alternating current system, for electric are cutting, welding and repairing comprising an are cutting, welding or repairing circuit in which the material -to be cut, welded or repaired constitutes one electrode and the cutting, welding or repairing material constitutes the opposite electrode, a transformer for supplying current to said circuit having preferably a closed circuit core, and primary and secondary windings arranged on said core so that when said electrodes connected directly to the secondary terminals are brought together and then separated within reasonable limits an arc is established and maintained bythe secondary voltage and current at the are E. M. F. then impressed across the arc.

12. An alternating current system for electric are cutting, welding and repairing comprising an arc cutting, welding or repairing circuit in which the material to be cut. welded or repaired constitutes one electrode and the cutting, welding or repairing material constitutes the opposite electrode, a transformer for supplying current to said circuit having preferably a closed circuit core, and primary and secondary windings on said core, said secondary winding being arranged in two partswhich co-act to deliver substantially a constant product 'of range.

13. An alternating current system for electric are cutting, welding and repairing .material constitutes the opposite electrode, a

transformer forsupplying current directly to said circuit having preferably a closed circuit core constructed to provide a plural- .ity of flux paths, primary and secondary within a*given .ciated with said secondary parts for assisting' in controlling the flux distribution insaid 'flux paths according to the electrical requirement of said welding circuit.

14;An alternating current system for electric arc cutting,-welding and repairing,

comprising an are cutting, welding or repairing circuit in Which the material to be cut, welded or repaired constitutes one electrode and the cutting, welding or repairing material constitutes thecopposite electrode, a

transformer for supplying current to said circuit and having a magnetizable core, primary and secondary WIIIClIIIgS So disposed on said core that the secondary winding, connectedin said circuit, delivers its power at the voltage of the arc.

15. An electric current system for are cutting, welding and repairing comprising an are cutting, welding or repairing circuit in which the material to be cut, welded or repaired constitutes one electrode and the cutting, welding-or repairing material constitutes an opposite electrode and a single means for supplying power to said circuit, said means delivering its total output at the voltage of the arc..

16. The method ofdelivering energy, having as desired approximately constant current, constant voltage or constant heat char acte'ristics each over a given range. to an electric are cutting, welding or repairing circuit; which consists in supplying alternating current to a transformer and therein'changing' the current through the medium of the core and windings arranged thereon. by selecting at, will a relation of core and wind ings such as will deliver the energy characteristics specified and connecting the selected terminals of the secondary winding to the are cutting, welding or repairing electrodes and thereafter striking an arc.

In witness whereof, I affix my signature.

. CLAUDE J; HOLSLAG.

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