US1188148A - Heat treatment of rails. - Google Patents

Description

r F. D. CARNEY & J. C. REED.

HEAT TREATMENT OF RAILS. APPLICATIQN nuzo AUG. to. Ian.

1 1 88, 1 48. Patented June 20, 1916, I

4 STATES PATENT OFFICE.

FRANK D. 'CARNEY AND JOHN C. REED, OF STEELTON, PENNSYLVANIA.

HEAT TRiiA'TMENT or was.

To all whom it may concern;

Be it known that we, FRANK D. CARNEY and JOHN C. REED, citizens of the United States of America, residing at Steelton, in the county of Dauphin and State of Pennsylvania, have'invented certain new and usea make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon,

which form a part of this specification.

Our invention relates to the improvement of the physical qualities of steelobjects of approximately uniform cross sectional 'area of any desired length, such, for example, as rolled shapes, and has for its object a novel method of treating such objects, to harden or toughen them uniformly throughout their whole length, or to both harden and toughen them, whereby the strength and resilience may be increased to the maximum strength and resilience compatible with the composition of the steel maybe secured, and utilized tracks of heaviest traflic, and have'found it practicable to secure remarkable uniformity in physical qualities, not only throughout the'whole length of each, but also as compared with others of the same composition treated in like manner; thus, in securing an elastic limit of over 100,000 pounds per square inch, the variations of elastic limit have not exceeded one-fifth of the variations of elastic limit found in similar material when treated in a furnace.

Having steel of a composition adapted to hardening and tempering whereby great increase of strength and durability was developed in objects conveniently heated and tempered, in view of the great need of more durable and reliable rails in the busier tracks of our important railways, the problem of furnishing a tempered rail has become urgent, and was not easy to solve.

Specification of Letters Patent.

I cluding the ports.

doors for introducing the rails made it im- Patented June 2c, 1916.

Application filed-August 10, 1914. Serial No. 856,087.

tried, on standard rails of usual length,

6., rails thirty-three feet long, the gasfired furnace was forty-five feet long, in-

This length, and the possible to maintain constant temperatures throughout the entire length, and hence, obviously impossible to effect reliable tempering inany one rail, or uniformity in a number of rails. Furthermore, the time required for'the best possible furnace treat ment, and the expensethereof, made it prac-- tically impossible to, bring the cost low enough to induce railways to consider.adopt ing such rails. This, with the large proportion of imperfectly tempered ra1ls,,,led .us to seek .for and devise a more reliable and cheaper method of tempering rails, capable of roducing a commercial product.

y our method of treating railway rails speaking, the steel billet, bloom. or ingot, having passed from the rolls where it is shaped, is taken directly 'tothe saws, then cambered, and immediately, while retaining as much as possible its initial heat, is dropped into -a cooling fluid, or, to say, quenched. The quenched rail isthen lifted from the quenching tank, while having a temperature of about 300 0., is placed on insulated supports, and a heavy current of electricity passed through it from end to end to raise the temperature to a proper temper drawing point, say about 450 0., or any other desired point above the quenched temperature. "This operation requires only a few minutes, after which the rail passes onto the ordinaryskids and receives the usual handling-to cold straighten, and to be drilled for splices. This method we have found to give a most satisfactory control over the physical properties of the steel. The tempering point, that is the temperature at which the hardness of the quenched rail is reduced .or drawn, can be controlled within a narrow limit, so that the properties of the steel in the rails may be made to conform to different requirements.

Another important advantage is that by varying the position and shape of the electrical contacts to the rails, we can produce to harden and toughen them, generally parts are similarly designated, and in which we'have diagrammatically shown a plant such 'as'we have successfully used in tempermg ra1ls-F1gure 1 1s a diagrammatic planview of a plant for tempering rails or bars of similarlength; Fig. 2 is. a side elevation,

, reversing type.

l0',,from motors 4 and 5.

partly; in section, of the quenching tank;

Fig. 3 is'an elevation showing one of the electric terminals from which current is .supplied to the rail end, and the cooling,

device which may be used. Fig. 4c is a modification of .Fig. 1, showing the use of a transformer in the electrical circuit; Fig.

5 is a further modification showing the use of a three phase current; Fig. 6 1s a modification of Fig."5,. where pairs of rails are connected in three single phase sets. Y

A represents a roller mill, either of a two high reversing type, or the threehigh non- The mill is driven by a motor 1, and its tables 2 and 3 are actuated The rails are de livered across the table 3 of the roller mill A to the saw-table B where they are sawed to proper length by the saws 6 and 7, after which they pass through a cambering machine, indicated atC, in order to have the proper. curvature given to them so that the rails when cold will be straight or very nearly so.

The specific construction and operation of these'machines is so well known in the art that a detailed description of their operation isdeemed unnecessar abuts. By varying the height of this abut- 'D is .a roller table, on which the cambered rails are received, and .is in all respects similar to' the-roller table B. Cooperating with this table are two or more air cylinders 8 whose pistons carry pushers 9 arranged to push the rails r laterally off the table onto inclined guides. 10 of a quenching tank E.

The lower part of the guides 10 is adjacent the lower end of a conveyer 11 which raises the rail from the water or. other quenching fluid in the tank and deposits it on the temper drawing tablev F, and on supports 12 thereof of insulating material where the contact-shoesor cable terminals 13 are-attached or otherwise placed in conducti-ve relation to the endsof the rails. These shoes 13 are more. clearly shown in'Fig. 3

and are of copper or other suitable material:

current to be supplied to the rails are attached. These'shoes have an upright portion 14. against which the end of the rail to which the electric cables conducting the through the rails.

the dotted lines in Fig. 3, and thus not heat the ends of the top of the rail sufliciently to draw its temper at the endsof the rail head as much'as elsewhere, and thus will leave this portion of the rail harder than elsewhere. The amount of heating of these ends of the top of the rail by convection will not be. very great, since the time during. which the current is passing through the rail is very short. However, if natural 'cooling in the air is not 'sufiicient, or the hard area is e to extend farther, along the head toward the center of the rail, we place a watercooled jacket 15 over the top of the rail as shown inF g. 3, in order to chill that portion of the rail which we wish to be harder than the restof the rail.

Direct current is supplied from a line L through a switch S and field rheostat 21 to a dynamo field 16, the armature P of which dynamo is driven byany suitable prime mover (not shown on the diagram). Alternating current will be generated in the armature P and will flow from P through the cable '17, contact or shot 13, rail 1' contact 13, cable 19, contact 13, rail 1' contact 13 ammeter A cable 18 and back to armature P.

V is a voltmeter placed across the terminals of the rail. By adjusting the field rheostat 21 any desired current may be caused to flow be about 1000 amperes per square inch of cross section using a 25 cycle current and volts pressure and two railslOO lbs. per yard and 33 feet long in series. With a fixed current indicated on the ammeter A, the voltage indicated on the voltmeter V will increase as the temperature rises. If a pyrometer is placed on one of the rails and the voltage noted when the desired temperature is reached, the temperature of other rails, having the same sectional area and the same composition, can be determined directly from the voltmeter.

' After the rails have been electrically reare moved onto the skids or cooling table 22. After cooling in the air, as usualwith rails, they are cold-straightened and drilled for splices. Q

. In Fig. 4, we have shown a transformer -'I connected from a supply line L for alternating current through the switch S, the low tension side being connected to the terminals or shoes 13' and 13. In this case the voltage V of the supply line is maintained constant, or nearly so, and the current shown on the ammeter A will drop as the temperature rises, and the desired temperature canbe determined by consulting the ammeter,

This we have found to v heated on the temper drawing table F they III ho'propcr currenthaving been previously detern'iined 'for similar rails by the use of a pyromcter.

In Fig. 5

we showconnections for three rails connected in a three phase-circuit, and

in Fig. 6 six rails connected as three single phase sets from a three phase circuit. \Ve havefound that it is desirable to use two rails. as shown in Fig. 4, three rails as shown in Fig. 5, or six rails as shown in Fig. (5, the last named being preferable. when using a three phase source of supply of current,

since it does not unbalance the system; all of which will be readily understood by those skilled in the use of electric current.

It is also desirable that two rails be treated simultaneously and side byside. since if only one rail is used.- and the leads from the transformer connected to each end, it

will cause a very much lower power-factor, which is ob ect1onable, since this reduces the capacity of the electricalmachinery and the lines. We havefound that by placing 'thetwo rails side' byside, but not in electrical contact, we more than double the power-factor over using one rail, so that a lower voltage is required to treat two rails in series than is required to treat one rail;

using the same density of current; this is because of the induction between the two rails.

\Ve find that with nn'pedance seven-times the resistance a 55% power-factor --is ob-.

tainable. This is probably due to the fact .that the rail has a high permeability at the ture, and also with the amount and kind'of current available.

We find that using a current density of 1000 amperes per square inch of sectional area-and from to-75 volts-pressure across two 33-foot rails connected inseries, side by side,'wecan heat six pairs of rails, raising the temperature from" 300 C, to 450 C. in six minutes, using a 25 cycle current. Direct current can be employed for this Work, but it is objectionable, since a very much higher density-of current avould have to be employed, there being no secondary currents set up withln the rails,

and owing tothe difliculty of transmitting such large currents any considerable distance without excessive losses, and the difli 'cult ies attending the providing of contacts fonthe larger currents required.

Of course the rails may be cold when treated, but it will take a longer time and more electricalencrgy to bring cold rails up to temper drawing temperature than hot rails, and in order to treat the rails economically we prefer to time the conveyer E so as to deliver the quenched rail to the tempering table at about 300 C.

It is, of course, obvious that other steel proportioned for quenching, which comprises quenching'the rail while retaining the heat incident to its manufacture in a quench-' ing bath, withdrawing the rail from said bath while still hot butbelow the temperdrawin point, and supplying a current of electricity longitudinally to the foot-of the rail to raise its temperature to the temperdrawing temperature.-

. 3. The method of tempering steel rails,

which comprises quenching the rail after rolling and while still hotfrom the quenching bath, passing an electric current through the rail to re-heat it to the temper drawing point, and then cooling the rail slowly.

4. The method of temper-ing rolledsteel shapes, which comprises quenchin the shape before becoming .cool after its r01 ing operation to a temperature belowthe temper drawing point, and while still hot heating the shape up to the temper drawing point by passing an electric current therethrough from end to end. i

5. The method of tempering steel rails, which comprises passing an electric current through the rail sufficient to heat it to its tempering point, while cooling the ends of the head of the raiL.

'6. The method of treating steel rails, whichcomprises quenching the rail to cool it below its tempering point, and then passing an electric current'through the rail sufficient to heat it to its tempering point while cooling the ends of the head of the rail.

7. The method of treating steel rails,

.which comprises rolling the rail, cutting it to length, cambering it, quenching it to re- I duce its temperature to the neighborhood of 300 0., then passing an electric current through the rail to reheat it to the desired tempering point. I

-8. The method of tempering steel rails, which comprises passing an electric current suflicient to heat the rails to the desired tempering point simultaneously through a plurality of rails that have been quenched belo the tempering point but yet hot.

steel shapes, which comprises heating a plu rality of parallel shapes to their tempering point by passinga three-phase alternating electric current through them, said shapes being in inductive relation to one another.

12. The method of tempering long, rigid steel shapes, which comprises heating a plurality of such shapes that have been cooled below theirtempering point, by heating them up to the, tempering point desired by passing a three-phase alternating electric current longitudinally through pairs of such shapes arranged in single phase sets, the rails of each pair being in inductive relation.

13. The method of tempering steel rails, which comprises quenching the rail before it has lost the heat incident to its manufacture to cool it below its temper-drawing point, then passing a current ofelectricit'y through the rail, while still hot, to reheat it to the temper-drawing point, and allowing the rail to air-cool.

14. Themethod of tempering steel rails,

. current which comprises quenching the rails before they have lost the heat incident to their manufacture to cool them below their temper-drawing oint, and then passing a of e ectricity simultaneously through a lurality of such rails fromend to end whi e still hot and in inductive relation to each other, to re-heat the rails to temper-drawing point.

15. The method of tempering steel rails,

which comprises quenching the rails before they have lost the heat incident to their manufacture to cool them below their temper-drawing point, and then passing a curwhich comprises quenching the rails before they lose the heat incident to their manufacture to cool them below their temper-draw-' ing point, then passing a current of electricity from end to end simultaneously through a plurality of the rails While still hot by supplying the current to the bases of the rails sufficient to re-heat them to their temper-drawing point, and then cooling the rails.

In testimony that We claim the foregoing as our invention, we have signed our names in presence of two subscribing Witnesses.

' FRANK D. CARNEY.

JOHN C. REED. Witnesses:

Geo. W. PARSONS, CHAS. R. HOLTON.

Images