US1501369A - Electric tempering - Google Patents

Description

July 15 1924.

E. RAMON DO ELECTRIC TEMPERING Filed Feb. 2, 192.1

g 5 0 d e a... July 15, 1924.

"UNITED ST TES-- 1,501,369 PATENT OFFICE.

mom, or'runnr, ITALY.

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; Application am February 2, 1921. mm 10.441301.

Toall'whomitmay concern:

Be it known that I, Erronn RAMONDO, a subject of the King of Italy, and resident of Turin, in the Kingdom of Italy, have I invented certain new and useful Improveused for manufacturing springs and effecting the hardening and tempering operation. 2 The system for transformin the electric energy into heat based on Jou es principle is already known. This invention is based on the same principle but, while in the usual transformation of electric into thermicenergy the resistance of the apparatus efiecting such transformation is calculated in accordance with the electromotive force of the available current, in this system the electromotive force of the current varies in 80 agreement with the ohmic resistance opsedby the material to be treated and to its heat efiiciency in respect of the temperagure (int which the treatment has to be efecte s5, My process consists substantiallyin the use of a current transforming apparatus from high to a low tension, an arrangement for obtaining the various'voltages required in the seconda circuit, and an apparatus for inserting t e steel tobe treated mto the secondary circuit. This invention is substantially characterized by means for I regulating the current in accordance with 'the dia am obtained through the electromotive Tdrce and its strength and the'treat- .ment to which the steel will be submitted.

Numerous experiments have demonstrated that steels havin been submitted to the same thermoelectric treatment do not show identical characteristics; these latter vary.

according'to the duration oithe' operation; this .occuri'n also11n the ordinary thermic treatment. herefore it'is absolutely necessary bot from an economical and teclmsi l, cal point of view, to vary the current charto be a full, clear,

to flow through the spr make the process an economicalone.

acteristics in accordance with the requirements of each case.

If the steel has a very hi h specific electric resistance this may produce a considerable fall of potential between the ordinary current conductors and the iece to be treated. However, owing to t e size of said piece, its ohmic resistance may be practically and inmost cases is much lower than the ohmic resistance of the entire electric circuit in which the piece is inserted. Assuming that a steel bar measuring 1 m.

length and having a section of 200 sq. mm. is heated, its resistance will be 0.0005 ohms,

while all the circuit, in an ordinary plant,

- has a resistance of about 0.0045 ohms, namely 9 times higher. It istherefore necessary that the current strength be kept within certain limits, in this case and for the different treatments from 6 to 10 amperes for each sq. mm. of section, according to the section of the iece to be treated, so that the insertion oi the piece produces the desired J oulels phenomenon. I The above said steel bar had a section of about 200 sq. mm. but a bar having a section of 50 sq. mini may have the same ohmic resistance as the former one, as in the case of a spring formed of wire of a section of 50 sq. mm. and 25 cm. length. It is evident that if the same-amount of electricity that was available -for the bar having a section of 200 sq. mm. is caused this latter will not only be heated but wi melt producing a short circuit. It would appear that by insertin a subsidiary resistance into the circuit an suitably varying its value-in rela tion with the piece resistance, it would be ssible to reduce the currentstrength acand therefore not at all convenient and its oifice would be to absorb the surplus elec-' tricity. It is evident that in this-case the cost of the process is not in proportion with 5 the weight of the piece to be treated, but is constant for each piece, whatever be its size, be it for, instance a bar 1 m. long and having a section of 200 sq. mm. or a round bar having a length of 0.25 m. and a section of'50 sq. mm, and this of course does not By the process form he object of this invention, the losses in t e different operations are reduced to those due to the apparatus efficiency and the current consumption is proportional to the requirements of each particular case, so that the highest efliciency is obtained and the process may be used for manufacturing purposes.

This result has beenobtained by means of, a transforming apparatus transforming the primary current having a very low volt-.

former and a series of identical transform-.

ing elements, the primary circuit of which is in series with the auto-transformer, while each element of its secondary circuit leads to terminals, by means of which and a special commutator it is possible to mount the'elements in series in parallel or in multiple series.

The auto-transformer and the primary windings of the under-transformation elements are mounted in series on the main conductor of the supply line in such a manner as to allow of a certain number of element pans to be cut out of the circuit in order to increase the number of combinations. The secondary winding of each element leads to two terminals, that, leaving each element in- I dividualized, allow of disposing by means of knife switches .and according to requirements, all the elements in parallel, in series or in multiple series.

Assuming to dispose of a current of 2000 volts and an auto-transformer capable of ten boosting voltages to 2200, 2400, 2600 up to 4000 volts, and each element giving a current transformed from 2000 volts to volts, it is evident that for each voltage of the auto-transformer an element may have different voltages of 5.5; 6; 6.5 up to 10.

By inserting 16 element pairs, it 1s possible to obtain all the desired voltages by suitably disposing said elements in such a manner as to obtain from 5 to 10 volts with a variation from half volt to half volt; of 10 to 20 with a variation from volt to volt;

I of '20 to 40 with a variation from 2 to 2 volts etc. By eliminating one or more element pairs, it is moreover possible to .obtain intermediate voltages so as to realize a great number of combinations satisfying not only all the work requirements, but also the eventual experiment requirements, as it is necessary in this kind of work.

In the annexed drawing is shown, by way of example, a diagrammatic form for the use of this process for the manufacture of hel- Evidently the same rocess may also advantageously used or the manufacture of semi-elliptical and elliptical springs.

To the main primary conductors C is connected an auto-transformer A, the secondary circuit of which is branched from one of the terminals of the winding aand one of the intermediate points 6, c, J, 6 by means of an interrupter or ordinary switch M or the like. In the secondary circuit of the auto-transformer A is mounted the transformer T, the primary of which is divided into of mounting all the elements in series or in parallel or, by their combined action, some element groups in series, according to requirements.

In the circuit S of the secondary ofthe transformer T is suitably inserted the starting rheostat R by means of an interrupter N and the piece D to be treated; this latter is preferably connected with the terminals F, allowing of the free expansion of said piece. I

In the main primary circuit C is finally inserted an automatic minimum cut out P the electromagnet of which is operated from any suitable current source, for instance, as shown in the drawing, from the lighting main L to which its winding is coupled in parallel by means of conductors O. In said conductors are inserted: an interrupter '1: and a press switch v situated near the piece D to be treated so as to be within reach of the operator charged with the heating of and 'v and therefore the automatic inter- 'or not and the arrangement willagain be in condition for operation.

When the work is finished, the current flowing to the main circuit is finally cut out by opening the interrupter i and the dividing knives Z.

In this arran ement either by operating the interrupter of the auto-transformer, or by mounting in series or in parallel or in multiple series all or some of the elements of the secondary of the transformer T by means of the interrupters I, and 1,, it is possible to-control the strength of the current to be fed to the steel iece under treatment in order to obtain t e desired result.

Claims: 1. In the art of tempering, transforming alternating current, re-transforming the transformed current and simultaneously proportioning the re-transformedcurrent to give an amperage suited to different lengths, cross-sections and weights of the work through which the re-transformed current asses. 2. In the art of tempering, transforming by step up auto-transformation alternatin current, re-transforming the transform current downward and simultaneously proportioning such retransformed current to give an amperage suited to the requirements of different lengths, weights and cross-sectioi: of the'w'ork through which such retrafisformed current passes. i

3. In the art of tempering, transforming alternating current, re-transforming the transformed current and simultaneously proportioning the voltage of the re-transformed current to give an amperage suited to the requirements of the work through which the retransformed current passes and f 'beparately controlling the Volta of the 30 current passing through the wor 4. In the art of tempering, transforming by step up auto-transformation .alterat' current, re-transformin the transforn i dt l current downward and simultaneously pro- '3 portioning the voltage of such retransformed current to give an ampera suited to the requirements of different lengths, v

weights and cross-sections of the work through. which such retransformed current passes, and separately controllin the voltage of the current passing throng the work.

5. In, electric tempering A apparatus, an v auto-transformer, means to ta e therefrom current of different values, a second transformer having a primary winding supplied with such current and a plurality o electrically interconnecti-ble secondary windings and means to supply current from said secondary windings.

6. In electric tempering apparatus a stepup'auto transformer means to take therefrom currents of different values, a second step-down. transformer supplied with such currents and comprising a primary windingand a plurality of secondary windings, means to variously connect said secondary windings to proportion the current to the work and a rheostat in circuit with said' second transformer and the work.

7. In electric tempering apparatus a stepup auto transformer means to take therefrom currents of different values, a second step-down transformer supplied with such currents and comprising a primary winding and a plurality of seconds windings, means to variously connect and secondary windings to proportion the current to the work and a rheostat in circuit with said second transformer and the work, and means at the work to disconnect the auto 70 transformer from the line.

In testimony that I claim the forego ng as my invention, I have si ed m name.

ETTOB R ONDO.

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