US1428529A - Electric welding - Google Patents

Description

F. S. CALDWELL AND A. M. BENNETT.

ELECTRIC WELDING.

APPLICATiON mu) JAN. 10. 1017.

1,428,529. Patented p 12, 1922,

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UNITED STATES I 1,428,529 PATENT oriucs.

.FRANCIS S. CALDWELL, O F COLUMBUS, OHIO, AND ALAN M. BENNETT, 0! WEST- FIELI), NEW JERSEY, ASSIGNOItS, BY MESNE ASSIGNMENTS, TO BURKE ELECTRIC COHTAINY.

ELECTRIC WELDING.

Application filed January 10, 1917. Serial No. 141-,507.

To all whom it may concern:

Be it known that we, FnANcIs S. CALD- WELL and ALAN M. BENNETT, citizens of United States, residing at Columbus, Ohio, and Westfield, New Jersey, respectively, have invented new and useful Improvements in Electric Welding, of which the following is a specification.

This invention relates to welding, brazing, repairing or the like treatment of metal by the electric arc. i

Usually the work constitutes one of the electrodes, the are being struck by touching a manually operated electrode against it. When the electrodes are separated the arc is drawn between them.

An initial impressed voltage higher than the working voltage is desirable. It makes more certain the striking of the are even if the initial contact is prevented by dirt, rust or other causes, from being the best, and also makes the incipient are more tenacious and has other advantages.

Accordingly the main object of the present invention is to provide improved means whereby the desired initial voltage may be obtained in an electric circuit of the character indicated and subsequently changed to normal working value.

It has erroneously been supposed that in striking the are it was necessary to have a very large current, greatly in excess of the normal working current, to heat the point of contact and initiate rapid ionization. Such excessive currents are, however, unnecessary, aswill presently be pointed out and are extremely disadvantageous for a multiplicity of reasons among which may be mentioned that the sudden overload wrenches the machinery, the apparatus must be made of greater capacity, the conductors of the circuits must be made .largerand, in fact, the whole installation must be made heavier and more expensive.

It is true that if a low initial voltage is employed, a large initial current is of ad: vantage in striking the arc to produce a profusion of vapors, thereby insuring a low resistance path for the incipient arc current. Otherwise the low voltage might be insuflicient to maintain the are.

It is not necessary that initial excessive current accompany a high initial voltage. A lower current will provide suflicient vaporization to furnish an arc path such thatthe arc will be maintained by the high voltage although the arc might fail on a lower voltage. It is feasible to make the initial current less than the normal current and then increase it to normal and to make the voltage initially high and then reduce it'to normal. By such procedure excessive load at any time may be prevented and the load may be applied by increments so that the disadvantages of sudden application of the load may be avoided. This may be accomplished by altering the other current controlling factors of the circuit as the impressed voltage is reduced so that the change in current will not follow the voltage but may be made to alter only slightly, may be unchanged or may change in the opposite (llI'GClJlOIl. In fact the regulation of the current on change of impressed voltage by factors independent of that voltage may be made use of to produce various desirable circuit conditions under difierent circumstances.

It is therefore another object of the invention to provide an improved method and apparatus for regulating the voltage and current conditions in circuits of the character described.

Other and ancillary objects of the invention will appear hereinafter.

In the accompanying drawings which illustrate the invention,

Fig. 1 is a diagram of apparatus and connections of an arc welding system embodying the invention of apparatus and capable of use in practicing the method.

. Figs. 2, 3, and 4, are diagrammatic views illustrating several arrangements of the generators supplying current to the circuit. Referring to the drawings the apparatus comprises. a constant potential main gene'rator 1, one terminal of which is connected with the work 2, or metal to be welded, repaired or the like. Connected in series with the main generator is a constant potential auxiliary generator 3 which, when in o ration, has its voltage added to that o the main generator. It Ina however, have a smaller capacity than t e main generator. In series with the auxiliary generator 15 a resistance 4 and the contacts of a relay 5.

An adjustable rheostat 6 is connected with the contacts of the relay 5. Conductor:

7 and 8 lead through. the contacts 9 of the ing the circuit relay 10, from the aim of the rheostat 6 to a point 11 in the connection between the main and auxiliary generators, this circuit through the conductors 7 and. 8 and the relay contacts 9 serving to make a shunt about the auxiliary generator, and its connected resistance, when the relay 10 pulls up. From the rheostat 6 connection is made through the coil of a load. relay 12 with the electrode 13 between which and the work 2 the are is drawn. The coil of the relay 10 is connected in shunt to the are when the loud relay 12 is energized, and in closing will not only close the contacts 9 of the shunt about .the auxiliary generator, but will also close the contacts 14 of the relay 10 thereby closing the circuit of the coil of'the relay 5 in parallel with the coil. of the relay 10 and therefore screw the are when the load relay is closed.

With the ports as shown in the position in the drawing the rheostat i is adjusted to give the appropriate steudying resistance in series with the are under working conditions end, the electrode 13 being separated from the work 2 and. no are started, the circuit is broken so that all the relays are deenergized and. all of their contacts are open cxcept those of the relay 5 which are closed. This is the 'nomopereting condition of the apparatus. If now tneelectrode 13 be touched agaiustthe worls current will flow through one terminsl of the main generator 1, through the auxiliary generator 3, resistance 4:, contacts of the relay 5, resistance 6, the coil. of the loud reluy 12, the electrode 13, the work; 2, and the conductor to the other terminal. of the generator; Current will then flow in the circuit indies/ted. This will energite the reley it? which will ciose its contacts thercby closing the circuit of the coil" of the relay 10 across the As soon as the operator withdrews the electrode from the work to such. an. extent that the dro of potentiel across the ore becomes sufficient, the coilof the relay 10 will become energized and close its contacts. The closing of the contacts 9 completes e low resistance shunt about that section of the circuit including the auxiliary generator 3 and which extends from the point ll to the of the rheostat 6.. This removes the potential of the auxiliary generator from. action upon the arc and closes the circuit for that genera-tor through the shunt mentioned, the resistance 4 and that portion of resistance of the rheostat 6 which is between the annexed the contacts of relay 5. This resistance is sufiicient to hold the current through the shunt within suitable limits: The existence of this current is merel momentary, however, for the reason that same movement of the relay 10 which closes the ehunt at the contacts 9 a so closes the contacts 14; thereby oompletof the coil of the relay 5 which thereupon picks up and opens the branch containing the generator 3. The are then exists under the impressed potential of the main generator 1, receiving its current through the steedying resistance of the rheostat 6. Should the operator touch the work with the electrode 13 or unduly shorten the are so that the potential across it is sufficient- 1y1 reduced, the relays 5 and 10 will let go t ereby opening the shunt and placing the auxiliary generator branch in circuit. This has the effect of not only inserting the auxiliary generetor in circuit, but also of inserting the resistance 4 and that portion of the resistance of rheostat 6 which is between the arm and the contacts of'relay 5. This resistance is so proportioned that it will hold the current in proper limits even when the arc is short circuited by bringing the electrode against the WOl'I. Upon a proper are being again drawn the auxiliary generator branch will be cut out as before described.

The resistance 4 may be of such value that, in conjunction with the other resistance of the circuit when the auxiliary branch is in circuit, the current flowing in the circuit under the voltage impressed by the main and auxiliary generators may be made equal to or less than the normal working current, and this resistance being cut out when the auxiliary generator is cut out, the current may actually rise when the impressed voltage is thus reduced or may remain stationary or vary in other relations according to the proportioning of the resistance.

For example: If during its operation the arc requires 200 amperes, there is a. fall of potential across the arc of 25 volts and the dro of potential in the circuit connections lea in to the are at this load-is 5 volts,

-then t e main generator should have an ampere capacity of 200 amperes and a voltage of 30. If we further assume that a voltage of 25 added to the voltage of the main generator will give proper voltage for initially striking the are and further that a current' of 40 amperes is appropriate for the initial current in the starting of the arc, then the ampere capacity of the auxiliary generator may be 46 and its voltage 25, the resistance in circuit being of such value that when the auxiliary generator is in circuit the current, even under short circuit conditions, that is with the electrode against the work will hold the current down to 40 amperes. en the auxiliary generator is cut out of circuit the resistance 4 is also cut out as well as a portion of the rheostat 6 so that while the impressed voltage, is reduced by 25 volts the reslstance of thecircuit is so-reduced that the current rises to normal value.

The striking voltage is not affected by the resistance in circuit for the reason that there is no drop of potential unless current flows.

Accordingly the full impressed voltage of the circult is upon the electrodes prior to and at the instant of making the striking contact.

The main generator and the auxiliary generator may be constructed in various'ways. For instance in Fig. 2 they take the form of a s ngle machine having a double wound armature of which 16 is the commutator of the main winding and 17 is the commutator otthe auxiliary winding, the two windings being then interconnected as shown in'the diagram of Fig. 1. 18 represents a driving pulley.

In the arrangement of Fig. 3 the main and auxiliary generator windings are on separate armatures on one shaft driven by a pulley 19. The main winding having a commutator 20 and the auxiliary winding having the commutator 21.

In Fig. 4 the main and'auxiliary armatures 22 and 23 are in separate machines se arately driven, asby pulleys 24 and 25. 1le the invention has been illustrated in what are considered its best applications it may have other embodiments without de parting from its spirit and is not therefore llmlted to the structures shownin the drawmgs nor to the precise details of the process as herein enumerated. i

What we claim is l 1. In an are system for weldin repairing and otherwise treating metals, t e combination with a main generator, of an auxiliary enerator, arc electrodes, conductors connectlng sald electrodes 1Il circuit with said generators and. means for rendering said auxiliary 2.

enerator inactive. v '11 an arc system for welding, repairing and otherwise treating metals, the combination with aplurality of sources of "elec- 'tromotlve force, arc electrodes, conductors connecting said electrodes in circuit with said sources and means'for rendering one of said sources inactive. I

3. In an arcjsystem for welding, repairing, and otherwise treating metals, the combination with a main generator, of an auxil- 'iary generator, arc electrodes, conductors connecting said electrodes in circuit with sa d generators and means responsive to .working'current for rendering said auxiliary generator inactive.

4. In an are system for weldmg,repa1ring and otherwise treating metals, the combination with a plurality of sources of electromotive force, are electrodes, conductors" connecting said electrodes in circuit with said sources and means responsive to working current for rendering one of said sources inactive.

5. In an arc system for welding, repair ing, and otherwise treating metals, the combination with a plurality of sources of electrom'otive force, are electrodes, conductors connecting said electrodes in "circuit with said sources and means for successively closing a shunt about one of the said sources and then opening the circuit of the last, mentioned source.

6. In an are system for welding, repairing, and otherwise treating metals, the combination with a-plurality of sources of electromotive force, are electrodes, conductors connecting said electrodes in circuit with said sources and means responsive to working current for successively closing a shunt about one of the said sources and then opening the circuit of the last mentioned source.

7. In an are system for welding, repairing and otherwise treating metals, the combination with a main generator of anauxiliary generator, arc electrodes, conductors connecting said electrodes in circuit with said generators, a load relay having its coil in the welding circuit, a shunt closing relay adapted to be connected across said electrodes and having its connections controlled by said load relay, a shunt about said auxiliary generator adapted to be closed by the contacts of said shunt closing relay, a relay controlling the circuit of the said auxiliary generator, the coil of the last mentioned relay being adapted to, be connected across the said electrodes and having its circuit controlled by the said shunt closingrelay.

8. In an are system for welding, repairing, and otherwise treating metals, the com-- bination with a main generator of an-auxil. iary generator, arc electrodes, conductors connecting said electrodes in circuit with said generators, a'resistance in series with said auxiliary generator and a load relay having its coil in the welding "circuit, a

shunt closing relay adapted to be connected across said electrodes and'having its connections controlled by said load relay, a

- electromotive force-on said circuit, striking an arcrto pass a current therethrough, and then increasing'said current through said are. v10. The method of operating an electric welding arc circuit comprising lmpressing an electromotive force on said circu1t,.striking an arc to pass a current therethrough,

and then increasing said current through I said are and decreasing force, I g

11. The method of operating an arc circuit for welding, repairing and otherwise said electromotive treating metals which consists in applying a high initial voltage to the circuit, and

cuit for Welding, repairing'and otherwise treating metals which consists in applying high initial voltage to said circuit, reducing said voltage and increasing the current for a given resistance of the are.

18. In a welding are system the combination with are electrodes, of a circuit connected thereto comprising means for impressing an electromotive force on said circuit to strike an arc and pass a current therethrough, and means for increasing said current and decreasing said electromotive force.

14. In an arcsystem for welding, repairing, and otherwise treating metals, the combination with means for applying a high initial voltage to the circuit, electrodes, conductors for connecting said means and electrodes 1n clrcuit and means for reducing the .voltage Without reduction of current for a given resistance of are.

15. In an are system for welding, repairing, and'otherwise treating metals, the combination with means for applying high initial. voltage to the circuit, are electrodes, conductors for connecting said means and electrodes in circuit,nand means for reducing the voltage and increasing the current as the voltage is reduced for a given resistance of arc.

In testimony whereof I FRANCIS S. CALD- WELL have signed this specification this, 21st day of October, 1916.

FRANCIS S. CALDWELL.

In testimony whereof I ALAN M. BENNETT have signed this specification, this 27th day of October, 1916'.

ALAN M. BENNETT.

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