US1211545A - Manufacture of steel. - Google Patents

Description

0.1. B. CHETWYND.

MANUFACTURE or STEEL.

APPLICAHON FILED MN- 2. 19 N- Patented Jan. 9, 1917.

\ 7 SHEETS-SHEET l.

6.1. B. CHEIWYND. MANUFACTURE OF STEEL.

APPLICAHON HLED JAN. 2. NH.

Patented .-Jan. 9

1 SHEETS-SHEET 2.

RR WN 6.1 B. CHETWYND.

MANUFACTURE OF STEEL.

APPLICATION FILED n.2, 1914- Patented Jmifs), 1917.

7 SHEETSSHEET 3- G. J. B. CHETWYND.

MANUFACTURE OF STEEL.

APPLICATION FILED JAN- 2. 1914.

Patented Jan. 9, 1917.

I SHEETS-SHEET 4.

' G. J. B. CHETWYND.

MANUFACTURE OF STEEL. APPLICATION men we. 2. m4.

Patented Jam, 1917.-

G. J- B. CHETWYND. MANUFACTURE OF STEEL.

APPLICATION FILID ml. 2. m4. 1,21 1,545.

Patented Jan. 9,1917.

7 SHEET8-SIIEEY i G. J. B. CHETWYND. MANUFACTURE OF STEEL.

APPLICATION FILED JAN- 2. 1914. v1,21 1,545. Patented Jan. 9,1917.

TSHEETS-SHEET I.

GGDFREY J OHN BOYLE CHETWYN D, OF WEST RIDING, ENGLAND.

MANUFACTTjRE OF STEEL.

Specification of Letters Patent.

Patented Jan.9, 1917.

Application filed January 2, 1914. Serial No. 809,972.

' .10 oil whom it may concern:

5 impetus with which the molten stream falls into the ladle, becomes so intermingled with the steel in the ladle that it has not time to separate completely therefrom and rise to the surface thereof before the steel must be run olf into the ingot or other molds before undue chilling of the steel in the ladleoccurs articles of various kinds made from such steel itis often found that the articles contain so muchslag and other impurities that they have to be discarded, frequently after considerable work has been done thereon, thereby incurring considerable loss of time and money and reducing the output of salable articles.

Now the object of this invention is to enable articles made of steel to be produced of better and more reliable quality throughout.

For this purpose, molten steel with admixed slag, produced by any process, after being tapped from any open hearth or other steel or iron melting, making or refining furnace or vessel (hereinafter. included in the term furnace) into a suitable receptacle in which it forms a deep bath and before it is run off therefrom into ingot or other molds is maintained in such a liquid condition by the aid of an electric current passing through the depth of the bath and for such a time, as to enable slag and other impuritics, including gases, in the molten steel, to separate therefrom and rise to the surface thereof, and also to enable the purified steel to he still run from the bottom or lower part of the receptacle, while in a suiiiciently liquid condition, into the molds as to proluce sound ingots or castings, so that articles made from such purified steel, being Consequently, in the manufacture of practically free from slag and other impurities or defects, shall be of more'reliable quality throughout.

In carrying out the invention there is passed through the molten steel in the receptacle above referred to, as soon as may be, a current of electricity of sufficient strength to maintain the steel at the re quired temperature or even to increase the temperature thereof. For this purpose the bottom .of the receptacle is provided with suitable conducting material to form one or more electrodes or poles suitably shaped and adapted for ready connection to and disconnection from an electric circuit. The opposite electrode or pole or electrodes or poles may be formed by one or more suitably shaped plates, rods or equivalent of suitable conducting materialadapted to be readily placed in such position, relatively to the molten metal that upon closing the electric circuit to which the electrodes 01' poles are connected an electric current will be caused to pass through the molten steel, substantially throughout its depth, either maintaining the temperature thereof approximately constant, or. it may be, raising it, while the slag and other impurities, including gases, in the molten steel are allowed to separate therefrom and rise to the surface thereof, after which the purified steel is run off from the bottom or lower portion of' the receptacle into a suitable mold or molds or other receptacle. The electrodes can be variously constructed and be variously adapted to be electrically connected up for use and the lower ones instead of passing through the bottom of the receptacle may be passed through the side or sides thereof close-t0 the bottom; or one or more of them may be. passed through the bottom of the receptacle and another or others through the side or sides of the receptacle and close to the bot-tom thereof. The receptacle may be an ordinary steel casting ladle or any other vessel, movable or stationary, in which a considerable depth of molten steel in relation to its horizontal cross section can be. maintained during the treatment thereof so as to allow of the slag and other impurities rising to the top of the steel but it is essential that the latter can be subsequently run off from the bottom or lower portion of the receptacle, it may and other impurities a l 1,3 ladle or into molds without or spout, into a bottom nozzle liability of the again becoming the ewith during the running This feature is essential to retaining the steel in the purified condi nolotained by the treatm. The receptacle may have a lining o2 ordinary refractory material, such as fireclay, constituting an acid lini all it is preferred to 'ncion between the bottom and receptacle curved shape. the treatment above reound advantageous first to cover the molten of steel. in the re ceptacie u t. cl: oi slag, say tor ennnple a -clmess several inches, which can readily bobtained from the nace from which t 1e steel is obtained or from other suitable source, and which owing to its nature, will quickly become solidified in so as its upper suris concerned, so the molten metal protected inst-- atmospheric effects during the purirying treatment, the electric current used passing through the n some case when layer of suliicient thickness and resistance is available, an elec ric are or arcs is or produced between the electrode or-elec d es and the molten of steel to prevent contact hctween these parts and to insure the presence oi suh'icient resistance in the electric circuit. The receptacle may .hrough interim strative drawin the accompany ng logs, igures 1 and 2 show respectively in side eleva a plan, arrangement oi plant suitable ior carrying the invention into practice and wher .11 two receptacles are used, namely one in which the purifying treatment carried out and the other, an ordinary casting; ladle, into which the purified steel is run and thence run into molds. ln l, the stationary support and associated parts for one side of the receptacle are removed. Fig. 3 shows partly in side elcvationand partly in vertical section, Fig. iin plan, with one half of the brick lining removed and 5 in side elevation t on at right angles to Fig. 3, the receptacle in which the purification process is carried out, and associated parts, shown to a smaller scale in Figs. .1 and 2, Figs. 6 and 7 show respectively in side elevation and plan, an alterna ive arrange ment oi receptacle and associated parts and Figs. S, 9, and are similar views to Figs. 3, 4; and 5 respectively of the receptacle used in such arrangement. ll isa detail lining 2, say of lireclay, and external brack- *ets 3 whereby it can be carried. by horizontal supports 4-, such as girders, arranged at opposite sides" oi a pit 5. Extending through the bottom of the receptacle 3. and itslinmg 2 are electrodes 6 made of iron rods that connected together by horiaontal conductors in the term of strip copper, to similar connecting strips 8 the upper bent ends S ct which serve as contacts arranged to bear upon other contact strips 9 carried by the upper SL1IflC8S Qf the supports l, so that when the receptaizle l is in position for use, the contact parts 8 receptacle and its contents whereby good electrical connection will be made between them. Thin sheets of good conducting material of a soft nature, for example lead, may be placed between the contact parts 8 and 9 to further insure good electrical connection. In the example, there are a number of electrodes 6 spaced apart and extending through the bottom of the ladle 1. Each electrode may conveniently be made as shown in Fig. 3 and to a larger scale in llyand comprises an iron red the inner end portion 6 of'which may advantageously be for about five inches of its length of small enough diameter, say of about eleven sinteenths of an inch, to allow the electric current used to raise its temperature to the melting point. Theouter portion 6 of the electrode which is of greater diameter is adapted to be screwed into a rod 6 of still greater diameter, the part (i having a squared portion 6 to admit of its being easily held while being screwed into place or removed for renewal. The part 6, constituting an enlarged extension of the part 6, 6, of the electrode is made as a metal bolt arranged to be fixed in metal distance washers or sleeiles 6 6 at the bottom of the ladle as shown. Gr the whole electrode could be made one piece. The two sets of contact strips .lare con nected by suitable conductors 10, 10* '(see Fig. 12), each to one end of the secondary windings 11 or 11 of two separate single phase transformers of which 12 and 12 are the respective primary windings. 18, 13 are two upper electrodes conveniently of graphite, fixed respectively in separate holders l l, l l carried by but insulated from separate vertically adjustable supports 15, 15 by which the said electrodes can be moved into and out of position for use in the receptacle 1. For this purpose each support 15, l niay, as in the esample, be mounted to slide vertically on a frame 17, being carried by crops 18, or el uivalent,

led around suitably arranged guide pulleys 19 to a winch barrel 20 by suitable operation of which the position of the lower end of each upper electrode 13-01- 13 can be readily adjusted to silit requirement. Automatic adjustment mayl' be used if desired. The frame 17, in the example, is mounted to turn about a vertical axis so that the upper electrodes 13, 13, when raised above the receptacle 1, can be readily turned into and out of position for use. The said upper electrodes 13 and 18 are respectively connected by copper conductors 21 and 21, which are flexible where necessary, to the other or opposite ends of the secondary windings ll and 11 of the two transfornr ers to which the lower electrodes 6 are con nected. The two ends a and f of the primary winding l2'are arranged to be respectively connected to one, namely 22, of the outer conductors 22, 23 and to the inner conductor 24: of a two phase three wire feeder by an oil switch 25, a throw over switch 26 and an isolating or main switch 27 through a meter 28. The two ends of the primary winding 12 of .the other transformer are arranged to be similarly connected to the other outer conductor 23 and the inner conductor 24 of the feeder by a switch and the throw over and isolatmg switches 26 and 27. through a meter 28.

Each primary winding 12, 12 may have a number of intermediate tap points, as shown at b, 0, (Z and 6, whereby the active length of the primary winding 12 or 12 and consequently the voltage generated in the corresponding secondary winding 11 or 11 can be varied to suit requirement. In the example, the point e is arranged to be connected to the inner conductor 24 through the throw over switch 26 and one or other of the remaining tap points, namely (Z in the example, is arranged to be connected to the corresponding outer conductor 22 or 23 by a separate oil switch 2T or 25. The switches 25, 25, 25" 25 and 26 are or may be interlocked so that switch 26 must. be closed before or opened after the others and when switches 25 and 25 are closed switches 25 and 25 must remain open or vice versa. 29 and 30 are single phase ampere meters for indicating ,the currents in the respective secondary circuits; 31 an ainpere meter to indicate .the resultant current "in the neutral of the secondary circuits;

hole or spout 36 through which the molten steel, after beingpurilied, is run off into an ondary current supply conductors l0, l0",

the upper electrodes l3, 13 being arranged and connected up as hereinbefore described with reference to Figs. 1, 2 and 12.

It is found important to make the diameter of the upper ends of the lower iron electrodes 6, where they extend through the refractory lining of the ladle, of relatively small diameter as hereinbefore described, in order that the current density passing through them during the purification process, as hereinafter described, shall not fall appreciably below about 1250 amperes per square inch so that the said upper ends of the lower electrodes shall become melted. The result of this is that as the metal of the Cir electrodes in the molten state will offer greater electrical resistance than when it is in the solid state, the necessary resistance in the electric circuit will not be limited only to the slag on the surface of the molten metal, and there is provided in the lower portions of the molten mass of steel in the neighborhood of the bottom electrodes, areas of intense heat that will facilitate the heating the whole mass of steel. As a consequence it is found that a steadier action on the molten steel is obtained, on the passage of the electric current therethrough, than would be the case if lower electrodes of large sectional area were used. Furthermore, as consequence of this steadier action, undesirable contact between the molten metal and the upper electrodes, by upheaval of metal due to too violent agitation therein, which would lead to short circuiting and its disadvantages, is minimized. Also, it is found advantageous to use during the greater part of the purification process, current of relatively low voltage, that is to say not exceeding about 65 volts and it may with advantage be even less than this, as a greater and more regular heating of the mass of molten steel is then found to take place than is the case when a higher voltage is used.

Into the receptacle 1 in each case a charge of molten steel in thenormally finished state in which it has heretofore bean cast into ingot or other molds is run from a. furnace and a thick layer of slag, say of about six to ten inches in thickness may be run into the re ceptacle upon the top of the molten steel, after which the upper electrodesare brought and electric current the slag and mass of posi ion 1' use "l pass througl- 1 steel. I

i.rranaelcents such as shown in the about forty tons of molten steel ally finished-state and obtained iary acid lined Siemens hilariearth furnace Was run into cid lined receptacle of circular a mean-internal diameter of an internal depth of about .r'ect. the receptacle being provided at acttoni with ten vertical iron electrodes hind hereinbet'ore referred to and own in 3 and 13., that were connec a as hereinbetore mentioned, to one end 01": secondary windings ll, 11 of the two stormers each of Which was adapted to duce a diilerence of potential varying 1 about 435 to 110 volts (see Fig. 12). molten steel Was covered With a layer or slag of about six to ten inches in thicks which immediately became solidified the surface as the top oi the receptacle a op n to the atmosphere. The two up elect: des 13, of graphite spaced feet six inches apart from center and connected to the opposite no secondary windings 11, 11 as dewere then brought into contact with "ed slag and the primary windings or transformers supplied with t from a two phase alternating; curoly oi 2200 volts and a periodicity per second, the secondary current and supplied to the electrodes 6 having a voltage at the couroi" the treatment of about 80 in proximity to the upper electrodes 1: cle trodes were caused to descend i until the passage of a steady out or the desired amount took place ely, in the example now being described, about'iilOO ainpercs per phase at the beii rising]; to about 4.200 amperes per a on cliuiugc of voltage, the current passand the molten steel. The current maintained in action for about twenty 1M, r 'i at 11 1'1 l was are it scams 5 ea 3, W nci too; :o r about ten minutes from the com uoei ent out the su 3 )lV at current and the l after the treatment thereof,

atom of the receptacle .ccond receptacle from which it nto molds. In other instances the i been treated in an ordinary casting shown in Figs. 8, 9 and 10 and om that through bottom nozzles ids, the treatment above described,

each having a diameter of about.

through slap; between the upper elec-' burnt With a brilliant flame, times varyins; Very considerably in colon Steel produced by the process above described is found to be improved quality as compared with steel not so treated, and to be remarkably tree from injurious iropurities, gases and slaggy inclosur-es, this being due to the above described treatment and to the fact that after such treatment the steel was run off from the bottom or the ladle in which it was treated in such a inannor that no slag Was brought away with it. Moreover the cost of trea steel. the manner described is very small, the treatment of forty tons of l L 1n the above example being effected with expenditure of about 245 Board of Trade units.

What I claim is 7 l. The process of purifying; been normally finished in a steel refining or melting furnace and trr to a receptacle so as to term there bath of molten metal y ing which consists in causing; electric current of large amperage to flow substantially through the whole depth of the molten metal and produce at tie bottom thereof small localized center of intense heat, main taining the current to enable impurities to separate from the molten metal and rise to the surface thereof and afterward running" oil the purified metal from the bottom oi the receptacle.

2. The process of purifyinpg steel that has been normally finished in 5368i making, refining or melting furnace and transferred to a receptacle so as to form therein a deep bath of molten metal preparatory to casting which consists in causing; electric cur rent oi": large amperage to flOWSLlbS'tElIltlfillj through the whole depth of the molten metal and produce a number of separate centers of intense heat disposed over the bottom of the receptacle and in contact with the molten metal therein maintaining; the con rent to enable impurities to separate from the molten metal and rise to the surface thereof and afterward winningof? the puri lied metal from the bottom of the receptacle.

3. T he process of purifying; steel that has been normally finished in a steel making,

ing, which consistspin causing electric cur a I at, 1 .153

. from the molten metal and rise to the surand produce a number of separate liquid centers of intense heat located at the bottom of the receptacle and in contact with the molten metal therein, maintaining the current to enable impurities to separate face thereof and afterward running oil the purified metal from the bottom of the receptacle.

at. The process ofpurifying steel that has been normally finished in a steel making, refining or melting furnace and transferred to a receptacle so as to form therein a deep bath of molten metal preparatory to casting, which consists in causing electric current of large amperage to flow substantially through the Whole depth of the molten metal and produce at the bottom thereof a zone of intense heat in contact with the molten metal, maintaining the current to enable impurities to separate from the molten metal and rise to the surface thereof and after- Ward running off the purified metal.

5. The process of purifying steel that has been normally finished in a steel making, refining; or melting furnace and transferred to a receptacle so as to form therein a deep bath of molten metal preparatory to casting which consists in causing electric current of large amperage to flow substantially Copies of this patent may be obtained for through the hole depth of the molten metal and produce at the bottom thereof a liquid center of intense heat in contact with the molten metal, maintaining the current to enable impurities to separate from the molten metal and rise to the surface thereof and afterward running ed the purified metal from the bottom of the receptacle.

6. The process herein described of purifyingsteel that has been normally finished in a steel making, refining or melting; furnace and transferred therefrom to a receptacle so as to form therein a deep bath of molten metal preparatory to casting, which consists in first covering the said bath of metal with a layer of slag and then causing an electric current to flow through said slag covering and substantially through the whole depth of the bath of metal and produce at the bottom thereof a zone of intense heat in contact with the molten metal, maintaining the current to enable impurities to separate from the molten metal and rise to the surface thereof and afterwardrunning oil the purified-metal from the bottom of the receptacle.

Signed at 10 New Court, Lincolns-Inn, London, England, this twenty-second day of December, 1913.

GODFREY JOHN BOYLE GHETWYND.

Witnesses:

WILLIAM GRoss, Farmamcx Wnmnn Pmron BROUGHAM- five cents each, by addressing the Commissioner, of Paton". Washington, D. G.

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