US1712227A - Method of and means for regulating electric arcs - Google Patents

Description

May 7, 1929. PAIGE 1,712,227

'METHOD OF AND MEANS FOR REGULATING ELECTRIC ARCS Filed March 31, 1922 Patented May 7, 1929.

PATENT OFFICE.

ARTHUR E. PAIGE, 0F PHILADELPHIA, PENNSYLVANIA.

METHOD OF AND MEANS FOR BEGULATING ELECTRIC ARCS.

Application filed. March 31, 1922.

My invention is particularly applicable to arc welding, my meansmf metallic electrodes, but is not limited thereto.

Electric arcs are inherently unstable, because increase of current therein is accompanied by decrease of resistance and consumed voltage, and vice versa, decrease of current therein is accompanied by increase of resistance and voltage, and such inverse current and voltage variations are cumulative, so that current may increase and resistance decrease until a short circuit of the source results; or current may decrease and resistance increase until the are breaks for lack of sustaining voltage. Consequently, it is impossible to supply such an are directly from a constant potential source. To overcome such inherent instability, an arc circuit must have a drooping volt-ampere characteristic, so that the tendency to increase or decrease of amperage will be immediately compensated and checked by decrease or increase of voltage, respectively, to such value as to maintain constant wattage at the are.

My improved method of regulating an electric arc includes varying the electric permeability of a vacuum in inverse relation with variations in amperage at the arc; and supplying more or less of a component of electric energy to the are through said vacuum; so as to maintain substantially coni stant wattage'at the arc.

As hereinafter described, my improved means for effecting such regulation include vacuum tubes of seve al different types. In its simplest form, si'Tc a tube includes two electrodes, in spaced relation, one a filament and the other a plate or other metallic element of greater area than said filament; said filament being included in such relation with the Welding arc, that the temperature of said filament tends to vary in correspondence with fluctuations in said are. Said filament and plate are also in a circuit which includes the are and a source of electric entrons between said filament and plate, and the potential component of the welding ent ergy, are varied by and in accordance with variations in the filament temperature, from Serial No. 548,299.

such a vacuum tube is provided with three electrodes, in spaced relation, including such a filament and plate, and a foraminous electrode, hereinafter termed the grid, between said filament and plate, through which the electrons aforesaid must pass; and said grid is included in a circuit with said filament and a source of electric energy, so that by applying positive or negative potential to said grid with respect to the filament, or varying the value of the energy thus applied, or both, it is possible to increase or diminish the flow of electrons between the filament and said plate and thus. adjustably counteract or increase the effect of the space charge in said tube, due to the electrons in the space between the plate and the filament, and thus control the value of the electric energy passing through said plate, without changing the plate potential or filament temperature. That is to say; a negative chargeof said rid will repel the electrons emitted by the lament, back toward the later, and thus decrease the current between said filament and plate, in correspondencewith the value of such negative charge; it being possible to thus entirely stop the flow of electrons from the filament to the plate it the grid is sufficiently negative. ()n the contrary, if the grid is positively charged, the negative space charge due to the electrons in the tube will be partly neutralized and the current through said plate correspondingly increased, while the filament temperature and plate potential may remain constant. So that, the plate current may be thus increased until the saturation current corresponding to the existing filament temperature is reached,

by merely increasing the positive potential of said grid. The principal advantage of the latter method of control is that the energy required to charge the grid to the desired potential is extremely small, due to the small capacitance of the grid with respect to the filament, whereas the energy transmitted through the plate to the arc may be of large Value.

My invention includes the various novel features of construction and arrangement and procedure hereinafter more definitely specified.

In said drawings; Fig. I is a wiring diagram showing a form of my invention including a vacuum tube with but two electrodes, with both the main and the regulating energy in the circuit derived from the same alternating current source.

Fig. II is a longitudinal sectional view of a preferred form of vacuum tube.

Fig. III is a graph indicating the drooping voltage characteristic aforesaid.

Referring to the form of my invention shown in Fig. I; the work to be welded is indicated at 153 and the arc electrode at 154, with the are 155 between them. The primary source of electric energy from which the welding current is derived for said are 155, is the alternating current generator 156, which may be equipped with means for adjustably varying the value of the energy which it supplies to the primary'coil 158 ofthe transformer including the laminated core 159, havin the leakage gap 160 which may be varied'by the relative movement of the core member 161, to vary the magnetic flux in said transformer. The welding circuit includes the secondary coil 163 on said core 159, and the conductors 164 and 165, respectively connected with said are electrode 154 and work 153. Said main welding circuit conveniently includes the manually opera-tive switch 166. The vacuum tube 168 includes the filament electrode 169 which is energized from said transformer coil 163 through the circuit which is in shunt rela tion to" said are 155 and includes the conductor 170, the variable rheostat 171, said filament electrode 169, and the conductor 172. Said vacuum tube 168 also includes the plate electrode 174 which is positively energized by saidprimary source 156, which is connected therewith by the. conductor 175, through the variable rheostat 176, conductor 177 and manually operative switch 178, in shuntrelation with said primary coil 158. Said primary and secondary circuits, respectively including'said coils 158 and 163, may

be coupled either directly through the conductor 180, or through the induction coil 181, or through said coil 181 and the condenser 182 in parallel relation therewith, in accordance with the adjustment of the switch 183. The function and effect of an induction coil and condenser thus arranged are hereinbefore explained. However, it may be observed that the apparatus including them as in Fig. I, may be tuned so that the oscillations involving said coil and condenser are in rhythm with the alternations in said are 155; with the effect of imposing upon the electric energy at the are 155, derived from said secondary coil 163,- an auxiliary potential component derived from said primary source 156.

As I prefer to provide automatic means to effect the relative movement of the arc electrodes with respect to the work at a constant rate; I have indicated such mechanism in Fig. I by two wheels, 192 and 193, respectively in engagement with the work and with the are electrode, and have exemplified their cooperative relation by indicating said wheels in contact with each other. However, such feeding mechanism may be of any suitable construction and may be actuated by any suitable means. For instance, such mechanism may be driven by an electric motor 195 either excited with energy from the source of,the main Welding current, or from the source of the auxiliary regulating circuit, when such sources are distinct, or from an independent source.

Although Ihave found it convenient to indicate a vacuum tube in Fig. I, in the conventional manner, predicated upon the formation of a vacuum chamber within a glass bulb; I prefer to provide vacuum chambers within tubes of a more substantial character, such as exemplified in Fig. II.

In Fig. II; the filament electrode is'indicated at 196 and may be a single wire, in coaxial relation with the plate electrode 197 which may be a cylindrical tube. The foraminous grid electrode 198, intermediate of said filament and plate electrodes, may be a helically coiled wire in coaxial relation with those electrodes. Said cylindrical plate electrode 197 may form the outer shell of the vacuum tube in conjunction with opposite end closures 199 and 200 so that said electrode 197 is exposed to the atmosphere to dissipate the/"heat which it manifests when included in a circuit which is highly energized. Both of said closures 199 and 200 may be hermetically sealed in connection with said cylindrical plate electrode 197 in any suitable manner, either integrally or by means of respective gaskets 201 and 202, I -owever, said closure-200 is in electric connection with said electrode 197 so that the exterior terminal 203 may be used to detachabl connect a conductor to said electrode. Sai closure 199 ma be formed of glass to permit inspection 0 the interior of the vacuum chamber'without breaking the seal thereof. Said filament electrode 196 may be stretched between the terminals 204 and 205 which may be insulated from said 010- sures 199 and 200 by respective bushings 207 and 208. Said grid electrode 198 is conven- .to the preclse'details of construction, .ar--

iently provided with oppositely counterpart disks 210, which are rigidly connected with its respectively opposite ends, so that it may be adjustably stretched by and between said terminals 204 and 205, although insulated from both of them by respective bushings 211 and 212. Said grid electrode 198 may be provided with exterior terminals 214 and 215 respectively in electric connection therewith at opposite ends thereof, by way of said disks 210 but insulated from said closures 199 and 200 by respective bushings 216 and 217, and be adjustably variably energized by any suitable means; for instance, by a shunt from a source of energy inFig. I, including a variable resistance.

The vacuum chamber within the inclosure formed by said cylindrical electrode 197 and its end closures 199 and 200 above described, may be exhausted and reexhausted, Without otherwise disturbing the hermetically sealed relation of the parts thereof, by way of the valve body 219, containing the rotary plug valve 220. Said electrode 197 is preferably coated and sealed with a vitreous insulating material 221. I have found it desirable to form both the plate and grid electrodes of nickel, and the filament electrode of tungstem, or platinum coated with barium oxide. The latter filament is advantageously operative at a lower temperature than the tungsten. However, other materials may be used.

Thermionic vacuum tubes of the character exemplified in Fig. II are the subject matter of the claims in my copending application Serial No. 556,695 filed April 26, 1922, for Letters Patent of the United States.

Although the current value should be maintained at approximately eight thousand amperes per square inch of cross section of a metallic electrode, for a welding are; it is desirable to limit the arc gap length to less than one-eighth inch, to minimize oxidation of the fused metal, and to constantly maintain the arc potential within the range from fifteen" to twenty volts.

aforesaid is maintained in substantial coincidence with the constant wattage characteristic, throughout that limited range. In Fig. III, I have indicated a typical 1.2 k. w. constant wattage characteristic, by the graph 223, with reference to the coordinates 224 and 225, the abscissae 224 indicating amperes and the ordinates 225 indicating volts. Although I have shown but one vacuum tube in each apparatus; any number of such tubes may be connected, in multiple, to .afiord the desired capacity.

Therefore, I do not desire to limit myself rangement orprocedure herein set'forth, as it is obvious that various modifications may be 7 made therein Without departing from the es- Therefore, it sufiices' if the drooping volt-ampere. charactertistic sential features of my invention, as defined in the appended claims.

I claim 1. The method of regulating an electric arc, which consists in providing means to vary the electrical permeability of a vacuum in definite relation with variations in the current through thearc, and to supply more or less electric energy to the are through said vacuum, in accordance with, and corrective of, said variations.

2. The method of regulating the wattage of an electric arc, which consists in varying the electrical permeability of a vacuum in in- Verse relation to variations in the amperage of the arc; and supplying the arc with more or less of a potential component of electric energy through said vacuum.

3. The method of regulating the wattage of an electric are, which consists in varying the electrical permeability of a vacuum in in- Verse relation to variations in the amperage of the arc, by corresponding changes in the temperature of a conducting medium in said vacuum; and supplying the arc with more or less of a potential component of electric energy through said vacuum.

4. The method of regulating an electric are, by varying the voltage at the arc in compensation for variations in the amperage at the arc, to 'thus maintain substantially constant wattage at the arc, despite fluctuations in the are resistance; which consists in providing a vacuum tube with a filament electrode which is variable in temperature in accordance with the current conducted therethrough, and including in said tube a plate electrode, in spaced relation with said filament electrode; including said filament in shunt circuit with the arc, so that when the resistance of the arc increases, an increased current is conducted through said filament and increases the temperature of said filament and effects a corresponding increase in the conductivity of the space between said filament and plate electrodes; and including said filament and plate electrodes in an auxiliary circuit, capable of supplying electric energy to the are at a higher voltage than that normal to the arc; whereby, when said resistance at the arc tends to increase and dlmmish the wattage at the arc bydiminution of amperage, the resistance in the space of said tube tends to decrease, with corresponding in? crease in the voltage supplied therethrough to the arc; to thus compensate by increment in voltage for decrement 1n amperage at the arc.

5. The method of regulating an electric by varying said potential component.

6. The'method of regulating the wattage of an electric welding arc, which consists in effecting relative movement of a metallic electrode and the work to be welded, toward each other at a constant rate varying the electrical permeability of a vacuum in inverse relation to variations in the amperage of the arc; and supplying the arc with more or less of a poten tial component of electric energy through said vacuum. f

7. The method of regulating the wattage ofan electric welding are, which consists in effecting relative movement of a metallic electrode and the'work to be welded, toward each other at a constant rate; varying the electrical permeability of a vacuum in inverse relation to variations in the amperage of the are, by includin in said vacuum an electrode, in such shunt relation with the are that its temperature is-varied in such inverse relation; and supplying the arc with more or less of a potential component of electric energy through said vacuum.

8. The method of regulating an electric welding are, which consists in automatically effecting relative movement of a metallic electrode and the work to be welded, toward each other at a rate which is constant relative to the rate of fusion of said electrode; andautomatically varying the components of electric energy in the arc circuit to maintain constant wattage at the arc.

9. The method of regulating an electric welding arc, which consists in automatically effecting relative movement of a metallic electrode and the work to be welded; toward each other at'a rate which is constant relative to the rate of fusion of said electrode; and automatically varying a potential component of the electric energy in the arc circuit to maintain constant wattage at the are.

10. The method of regulating an electric welding arc, which consists in automaticallyefi'ecting relative movement of a metallic electrode and the work to be welded, toward each other at a constant rate; and automatically maintaining constant wattage at the are, by varying a component of the electric energy in the arc circuit.

11. The method of regulating an electric welding are, which consists in automatically effecting relative movement of a metallic electrode and the work to be welded, toward each \other at a'constant rate; and automatically maintaining constant wattage at the arc, by varying a potential component of the electric energy in the arc circuit.

'12. In means for regulating an electric welding are, the combination with means arranged to efi'ect relative movement of a metallic electrode and the work to be welded, toward each other at a constant rate; of means arranged to vary the electrical permeability of a vacuum in definite relation with variations in the amperage of the are, including a vacuum tube containing two electrodes; first, a filament capable of variation in temperature in accordance with the value of electric energy conducted therethrough, and second, a plate electrode, capable of receiving electrons from said filament; means including said filament electrode in shunt circuit with the are; and means including said filament and plate electrodes in an auxiliar circuit, capable of supplying more or less 0 g a potential component of electric energy to the are through said vacuum, in accordance with such variations in permeability of said vacuum.

13. In means for. regulating an electric welding arc, the combination with means arranged to effect relative movement of a metallic electrode and the work to be welded, toward each other at a constant rate; of means arranged to vary the electrical permeability of a vacuum in definite relation with variations in the amgerage of the arc, including a vacuum tube ccntaining two electrodes; first,

. a filament capable'of variation in temperature in accordance with the value of electric energy conducted therethrough, and second, a plate electrode, capable of receiving electrons from said filament; means including said filament electrode in circuit with a source of electric energy; and means including said filament and plate electrodes in an auxiliary circuit, capable of supplying more or less ,ot a potential component of electric energy to the are through said vacuum, in accordance with such variations in ermeability of said vacuum.

14.- Means For. regulating an electric welding arc, including the combination with means adjustable to effect relative movement of a metallic electrode and the work to be welded, toward each other ata rate which is constant relative to the rate of fusion of said electrode;-of means arranged to automatically relatively vary the components of electric energy in the arc circuit, to maintain constant wattage atthe arc. i

15. Means for regulating an electric welding arc, including the combination with means adjustable to effect relative movement of a metallic electrode and the work to be welded, toward each other at a'rate which is constant relative to the rate of fusion of said electrode; of means arranged to automatically vary a potential component of the electric energy in the arc circuit to maintain constant wattage at the arc.

16. Meansfor' regulatingan electric welding are, including the combination with means adapted to automatically effect relative movement of a metallic electrode and the Work to be welded, toward each other at a rate which is constant relative to the rate of fusion of said electrode; of means arranged to automatically maintain-constant wattage at the are, by varying a component of the electric energy in the are circuit.

17. Means for regulating an electric Welding arc, including the combination With means adapted to automatically effect relative movement of a metallic electrode and the work to be Welded; of means arranged to maintain constant wattage at the are, by varying a potential component of the electric energy in the arc circuit.

In testimony whereof, I have hereunto signed my name at Philadelphia, Pennsyl- Vania, this twenty-seventh day of March, 1922.

ARTHUR E. PAIGE.

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