US1201225A - Electric furnace. - Google Patents

Description

H. W. GILLETT.

ELECTRIC FURNACE.

APPLICATION FILED MAR. 11. 1916.

1,201,225. PiltGIltGd 0111. 10,1916.

5 SHEETS-SHEET I.

H. W. GILLETT.

ELECTRIC FURNACE.

APPLICATION FILED MAR. I1, 1916- 1 ,201 ,225. Patented Oct. 10, 1916.

5 SHEETS-SHEET 2.

Fez/071 60):

H. W. GILLETT- ELECTRIC FURNACE.

APPLICATION FILED MAR-[1,1916- 1,201,225.

Patented Oct. 10, 1916.

5 SHEETSSHEET 4.

v o o Inventar:

UNITED STATES PATENT OFFICE.

HORACE W. GILLETT, O]?- ITHAGA, NEW YORK.

ELECTRIC summon,

tain new and useful Improvements in Electric Furnaces, of which the following 1s a specification. 4

This invention relates to electrlc furnaces and more particularly to electric furnaces adapted to be rockffedwhile running, of the indirect arc type, iii which an arc is, or arcs are, struck between or among two or more electrodes, the are or arcs being over the charge to be heated but not struck between electrode and charge. I

More particularly, it relates to such furnaces when applied to the meltlng of alloys containing zinc, such as the various brasses, and German silver, or containing manganese as ferro-manganeser One object of my invention 1s to provide means for more complete stirrmg of the charge and for more complete contact -be-. tween the furnace walls and thev charge in furnaces of the type described in pending application Serial No. 59868, filed November 5,1915. w I

The furnace described in the above-mentioned application may be built with hearths of various shapes as sphero1d or ovold, but preferably in the form of a cylmdrlcal drum, with the axis of the cylinder hor zontal; arc electrodes" entering on the horlzontal axis and moving with the furnace, the whole being supported so as to be capable of rotation or oscillation about the axis. While my experience with such a construction has been mainly with such a drum osclllatlng back and forth through a nearly complete.

arc of a circle, it is of ceurse to be understood that complete rotation as well 1s c011- 'templated as within the scope of this. dis- ,closure and my use of the word osc llate isto-be understood accordingly. In such a furnace, so oscillated, the charge is mixed to acertain extent, as the friction between the moving hearth and the chargetends. to produce a circulation of the metal. The refractory hearth is washedby the charge over the'circumference, save for the space occupiedlby' the combined charging door and.

pouring spout. Or, if desired, the chargmg door could be made in the headof the drum-,fgrbove the metal level and. a tap hole Specification of Letters Patent. Patented Oct; 10, 1916. Application filed March 11, 1916. Serial No. 88,686.

provided in one end. By suitably-"closin this tap hole, the furnace mig in onedirection only instead fof oscillated, 1n which case' the whole 'c1rcumference..--

would be washed by. the moltencharge. However, the. heads of the drum, in a fur-L t be rotate nace' oscillated or rotated about a. horizontal axis, are washed, by a charge of molten metal for example, only. belowthe. metal-, which is heated by the are and which con-:. ducts heat away to the outside of the furlevel, leaving a considerable end wall space nace where it is 16st, Moreover, in such a furnace, oscillated or rotat'ed-on a horizontal axis only, thereis no tendency toward motion of the meltfrom side to side. It has been found, in the operation of such; a

furnace on alloys high in zinc content thatf even with rapid oscillation, the stirring o the metal by oscillation or rotation on a horizontal axis, is not great enough to overcome completely the tendency toward overheating of the surfaceof the melt, so that when the furnace is operated to charge or to pour, too great losses of zinc, released from the superheated surface, may occur. A still more vigorous stirring of the melt to. avoid local overheating is desirable.

Such increased stirring can be produced by giving the furnace an added end to end motion. This; can be done by any suitable means, suchas mounting the furnace described in application Serial. Number 59868, together with its support- Y ing rollers and driving and reversing mechamsm and motor on a platform, which platform is'itself'mounted on rockers, so that platform and furnace may be rocked by suitable mechanical means, such as an automatically reversing electric motor, a jointed pistonarm or a rocker arm on a wheel. The furnace itself is thus given two oscillatory movements, one describing a 7 complete or nearly complete arc of a circle about the axis on which the electrodes lie,

and the other describinga smaller are, less than 180, about an axis perpendicular to the first axis and'lying either in the same horizontal plane with 1t or. parallel to that plane. The furnace may then be termed a' doubly, oscillating furnace. Or, the furnace with charging doors and pouring spout or tap-hole made tight enough to prevent leakage of the charge, may be rotated in one direction on the axis on which the electrodes 1 0 lieand oscillated through an arc of a circle on an axis perpendicular to that axis and lying either in the same plane'with it or parallel to that plane. -The endwise tlltlllg of the furnace due-to the oscillating on the rockers, produces an end-to-end motion in the charge, stirs it and prevents local overheating. It also washes the end walls with rocked from end to end may be adjustableso that the chargej'may be made, in the, extreme position ofthe furnace, to cover the end wall as nearly as possible without running into the hole through which the electrode isintroduced, whether a large or small I charge be used.

After the heating of the charge'is. completed, the double oscillation is stopped with the electrodes horizontal and the furnace is then tiltedon the axis of the electrodes to pour as in the usual forms of tilting furnaces. Or, if what would be in a stationary furnace a tap-hole, is used in one end, the

furnace may be stopped in such a position that the tap-hole is directly below the electrode, but that the end of the'furnace bear-- ing the tap-hole is atthe uppermost posi-.. tion of its endwise motion. By then rocln' ing so as to lower the tap-holeend, the charge may be poured out, using the taphole as a spout. Or, bystopping the oscillatory motions with the taphole below the electrode but'with the furnace end-bearing the tap-hole at the bottom of its endwise i from below the surface, thus making it motion, the metal may be tapped out from below the surface. Bysuitably tilting the furnace on the rockers, the hydraulic head may be kept lowwhile still drawing metal easier to stop the flow when desired.

My improved furnace differs from the one described vin application Serial No.

59868 in that the axis on which the electrodes lie and about which the furnace'is circumfer'entially oscillated or rotated is no longer substantially. horizontahf. but said axis is itself kept in motion and continually changes its angular displacement from the horizontal. This continual displacement from the horizontal may befobtained by any suitable means, suchas the mountingof the furnace and driving and supportin mechanism on a platform resting on. roc ers, or

swinging on trunnions. O oth re d t motion may be obtained by-supporting the furnace. on-" four or more eccentric gear overheating wheels or rollers or similar supporgs, running on suitably-shaped gears or in uitably shaped tracks on the furnace shell, so placed as to givethe furnace an endwise motion as well" as a circumferential motion, in which case-the axis of circumferential motion will I not continually lie in a vertical plane as in the case when rockers are used, but will de scribe the whole or a portion of a double cone, that is, two cones each having its apex at the middle point of the regularaxis of the cylinder. Various other means of producing continual displacement of the axis about which the furnace is-oscillated or rotated,'by which two distinct motions are produced, the charge mixed to prevent local and the refractory lining brought practically wholly in contact with thecharge might'loe used without departing from the spirit and scope of my invention.

Figure 1 is a vertical sectional elevation of. my furnace construction taken along the anis of the electrodes, which are shown in elevation. Fig. 2 is a sectional elevation of the refractory cylinder and actuating mechanism therefor, taken along a plane passing through the central portion of the cylinder, located at a ninety degree angle from .that in which the plane of Fig. 1 lies. Fig. 3 is a side elevational view, similarly positioned tothat constituting Fig. 2, designed espe 'cially to show the roller supports for the refractory-cylinder and-the mechanism for causing its rotation about its axis. Fig. 4: is tit-diagrammatic side-elevation, showing the possible use of intermittent reversing mechanism on the rotatable refractory cyl- Qinder. Fig.5 is a side elevational view of the portions of the automatic reversing mechanism supported from the base of the furnace .mechanism, adapted to cooperate I with-the complementary parts on the refractory cylinder. Fig. 6 isean. end elevagional view of the automatic reversing memers. refractory cylinder taken through its axis, showing the location of the'tap'hole in one end of the refractory cylinder, instead of through its curved side wall. Fig. 8 is a sectional elevation along a plane perpendicular to the-axis of rotation of the refractory cylinder, showing especially the positioning of-roller's' against the ends of the cylinder so as toresist endthrust. Fig. 9 is a diagrammatic showing and Fig. 10 an end view of a modified form of construction in which the regularlaxis of the cylinder ,describes a double cone.

A preferredform- 'of my invention is shown "in- Fig: 1, a sectional] elevation made through the electrodes. in which is provided a cylindrical shell 1 having alining which" may be of any. refractory .or refractories suitable for the use to which. the

.furnace isitojbepuuu- For brass melting Fig. 7 is a sectional elevation of the a stratified lining, consisting of a layer .2' of kieselguhr brick, or red building brick, a layer 3 of a heat insulating brick, less refractory than firebrick but of lower heat conductivity, another layer 4, of firebrick,

and an inner layer-5, or asbestos cement 4 -which will stand 1700 C. before fusion, or

of carborundum, is suitable. Closely fitting into holes in the centers of the heads'of the. drum are adjustable arc electrodes 6, which are preferably capable of endwiseadjusta ment but otherwise stationary in respect to the furnace andpartaking of the motion'of thefurnace. These electrodes'maybe 0f 1 carbon or graphitefand; for use in melting .1 alloys high'in zinc,-; as"-=yell'ow' brass-,1 they.

I may be-cored with a mixture of carbon" and.

or sodium silicate, or with one of carbon sodium silicate and calcium .fluorid, or.with

other Well i' known materials which give a flaming arc, that-is, one which is not so liable to rupture,&which'can be. drawn-out longer and which is easier .to regulatethan the ordinary carbon are m; an atmosphere I shown in application Serial No. 59868, be-

ing applicable to this furnace. The electrodes are connected by clamps 7 .to cables I or other. flexible conductors 8 which allow freedom of motion to the furnace and .are in turn connected to a. source of electric."

energy, not shown. The bodyof said furnace is substantially the same as is shown: in detail in application Serial Number 59868. The circumferential oscillatory motion is imparted to the furnace by suitable means such as various. well known systems of mechanical gearing, or, preferably by an automatically reversing motor 9 which drives'a gear 10 which mesheswith a gear 11 on the furnace. The motor 9 receives its power through flexible leads 12, so placed that they allow the rockingv motion of the platform to be made without injury to them. The furnace body may be supported on four .or 'more'idlers 13Jand the end thrust, due to the endwise motion, is taken up by two or more other idlers' 14. The furnace body, driving gear, and sup porting ,idlers may all be mounted on platform 15 which is supported on two or more rockers 16 which rest on roller bearings 17 on curved supports 18. The rockers and all that is supported by them may be moved back and forth by suitable means such as a toothed gear segment 19 attached to the platform 15 meshing with a gear 20 which is driven by another automatically reversing motor not shown in Fig. 1. The platform 15 is preferably at the floor level when in its median position 21 and the supporting and driving means below the platform are placed in a pit. Hoop-like tracks 22,

with flanged edges 23 serve as bearing su'r faces for the shell to rest on upon the idlers '13, and ring-like tracks 24 on the-ends of the shell, alsowith flangededges 25, give similar contact surfaces. fofi'the end thrust idlers 14. f The 'single.-;jrollers of the idlers 13 or 14 orboth mayflhfireplaced by double roller cradles,",or .some or 'all'of the idlers may besupplied with springs which allowfor irregularities .in the bearing surfaces from expansion or-other causes, according to well known practice in the support of rotary kilns. -'Or the furnace ma if desired, besupported on trunnions, t e shafts of which arelhollow and are of large enough 'isflilze to allow the electrodes to pass through 1 em.

. qf Fig. shows'the furnace tilted on the rocke'rs into-one. jextreme position. metal level X Y takes the position X Y .at the other extreme position. If the fur- The nace. is turned 180about the axis on which the electrodes lieand then rocked on the other axis to the extreme positions, the, metal reaches in turn the points Z and Z, so that the only parts of the refractory lining not washed by metal are a portion about the fcombined charging door; and pouring spout and .small rings about the holes through which the electrodes enter, these rings being left unwashed to prevent danger of the charge entering the electrode holes. These rings are so small that they are elfectually shielded-:from'the are by the shadows of the electrodes. By' adjusting the rate of endwise oscillation the end-toend motion and hence the agitation of the charge may be varied atwill.

Fig. 2 is a vertical cross section of the furnace taken midway between the drum heads'when the platform 15 is in its median position. A pouring'spout 26 is provided, and a-tightly fitting cover 27, opened and closed by suitable .means not shown,

closes the charging door 28.

. The rocking mechanism below-the platform ,is driven by suitable means, such as an automatically reversing electric motor 29 which is connected by the-flexible leads 30, so placed as to allow freedom of motion without injury, to a source of electric power.

Fig. 3 is an end view of the furnace with the platform 15 in its median position showing how the shell 1 rests on the supporting idlers 13 and against the end thrust idlers.-v

14, the latter in the ring-shaped .track 24 with flanged edges 25, and the former in the hoop-shaped tracks of which the flanged edge 23 only is visible.

The automatic switches and operating mechanism by which the reversing motors are made to reverse, not shown in Figs. 1, 2,

and 3, are shown in Figs. 4and 5.

Fig. 4 shows diagrammatically how fingers 31 and 32 projecting from one end of the furnace shell may be made to throw a reversing switch 33 so as to make electrical contact either atthe switch terminals 34 or 35. The wiring of the switch 33 and motor 9 (Fig. 1) is so done that when contact 34 is closed and 35 open, the motor revolves in such direction that the furnace shell turns counter clock-wise,'and when contact 34 is open and 35 closed, it revolves in the opposite direction and the shell turns clock-wise. In the diagram the furnace is shown with the finger 31 closing contact 34 and opening 35. The metal level is then at A. B. From this position the shell turnscounter clock-wise till the metal levelis at A B when finger 32 throws the switch 33 so that contact 34 is' opened'and 35 closed, when the shell turns clock-wise till the metal level reaches A B again. In order to be able to wash the whole circumference of the lining save that from A to B, i. e. the width of the charging door and pouring spout, whether a normal, large or small charge, with consequent different depths of metal, the fingers 31 and 32 are mounted. in slots 36, 37 in suitable frames 38, 39, so as to be movable, and held at any desired point by the wing nuts 40, 41. If fingers 31 and 32 are moved closer together, the furnace will rock farther in both directions and a smaller charge can still be made to reach the points B and A. If fingers 31 and 32- are moved farther-apart, the furnace will not rock so far in either direction and a larger charge can be used without passing,

the points B and A. In order to tilt the furnace for pouring so that the metal will run out of the spout 26,-finger 31 is turned, after loosening the wing nut 40, so that it no longer projects beyond the shell or engages the switch 33. By then throwingthe switch 33 by hand to make contact with 34,

- the spout can be depressed into pouring position and by throwing 33 to make contact with 35, raised again so that metal does not fiow from the spout.

Fig. 5 shows a side view and Fig. 6 a cross section of an automatic reversing device by which the tilting of the platform 15, and hence the end-wise motion of the furnace, is controlled; This is analogous to the methodused to control the circumferential oscillation of the shell. A reversing switch 42 with contacts 43 and 44 is so wired to the motor 29 (Figs. 2. and 3) that when contact 43 is closed and contact 44 open, as shown,

' the platform rocks counter'clockwiseand when 43 is open and 44. closed, clockwise.

The fingers 45 and 46 are so placed that the line M N of the platform 15 may rock clockwise till it reaches the position X Y (corresponding to the metal level X Y in the furnace shell, Fig. 1) when finger-46 closes contact. 43 and opens 44, when the platform rocks counter clockwise to the position X Y (corresponding to the metal level X Y in the furnace shell, Fig. 1), when finger 45 opens contact 43, closes'44 and starts the reverse motion. These fingers may pass through holes 4748 in the platform, he pivoted M49, 50 and be adjusted in the slots 51, 52 in the frames 53, 54, and held in place by the wing nuts 55, 56. By moving the lower ends of fingers 45, 46 to gether, a greater throw can be obtained and the same meta-l level reached with a smaller charge, or by moving them apart, a lesser throw for a larger charge, may vbe had. The frames 38, 39; (Fig. 4) and 53, 54 (Fig. 5) may be graduated to show the proper position of the fingers for any given charge. By using motors 9 and 29 which are capable of adjustment as to speed of rotation, the

rates of'both oscillatory motions can be con trolled and any desired degree of stirring of the charge obtained.v Either or both oscillatory motions can be. given to the furnace by many other well known mechanical means without deviating from the spirit and scope of my invention.

If it is desired to tap the metal from below the surface instead of pouring over-a spout, the spout may be omitted, and a tap hole 57 provided in one end, closed by a suitable plug as shown in Figs?" and 8. Charging doors 58, 59, closed by tightly fitting covers 60, 51 may be provided either on the circumference, as 58, or in one or both ends, so placed as to be above the metal level at all times, as 59, or in all of these locations. Of course both a pouring "spout on the circumference and one or more tap holes on one or both ends may be provided in the same furnace and any of them used in discharging the furnace. When tap holes are provided, the single end thrust idler 14 of Figs. 1 and 3, if the idler supporting rocker tracks in the pit so as to protect them from spilled metal. P

A guard rail should, in all cases, be placed about the pit to prevent danger of a work man getting a foot caught between the rock ing platform'and the edge of the pit.

One method of mounting the furnace shell to give endwise-motion to the charge is shown in Fig. 9 in which the shell 1 is 'provided with annular tracks 22 resting on eccentric supporting rollers 13, driven .by shafts 62 which are connected by gearing (not shown) so that these rollers always maintain the same relative position to each other. The electrodes. 6 and the combined charging door and pouring spout 26 are also shown. While Fig. 9 shows a friction drive,

said hearth being mounted to oscillate circumferentially about its regular axis, are electrodes between which the arc is struck passing through the ends of said hearth and oscillating therewith, said hearth being also mounted to oscillate in endwise fashion about a horizontal axis substantially perpendicular to the said regular axis.

2. An electric arc furnace comprising a substantially cylindrical refractory hearth, adjustable arc electrodes passing through the ends-of said hearth and rotating therewith, said hearth being mounted to rotate about its regular axis, and being mounted to oscillate about a horizontal axis substantially perpendicular to the said regular axis. 3. An electric arc furnace comprising a substantially cylindrical refractory hearth, arc electrodes passing through the ends of said hearth and oscillating therewith, said hearth being mounted to oscillate about its regular axis, said hearth being also mounted to oscillate in such manner that the regular axis describes a portion of a double cone.

4. An electric arc furnace comprising a substantially cylindrical refractory hearth, adjustable arc electrodes passing through the ends of said hearth and rotating therewith, said hearth being mounted to rotate about its regular axis, said hearth being also mounted to rotate in such a manner that the regular axis describes a double cone.

5. An electric arc furnace comprlslng a substantially cylindrical refractory hearth,

axially arranged arc electrodes therein, means for rotating the hearth about its axis,

and means for contemporaneously oscillating the hearth and its electrodes about an axis perpendicular to its axis of rotation.

6.. An electric arc furnace comprising a substantially cylindrical refractory hearth, arc electrodes passing through the ends of said'hearth, and means for contemporaneously oscillating the hearth and its electrodes about its own axis and' about 7 an axis substantially perpendicular thereto.

7. In an electric arc furnace, in combination with a substantially cylindrical refractory hearth, electrodes axially arranged through the walls thereof, means for sup porting said hearth in position to rotate about its axis, means for positively imparting rotative movement thereto, means for supporting the hearth and its supporting means in position to'oscillate, about an axis substantially perpendicular to said axis of rotation of the hearth, and means for actuating the hearth and its immediately supporting parts about said last named axis as a center. v

8. In an electric arc furnace, the combination of a substantially cylindrical refractory hearth provided with axially arranged electrodes, and a plurality of means for contem-' poraneously causing the oscillation of said hearth about axes substantially perpendicular to one another.

9. In an electric arc furnace, in combination with a substantially cylindrical refractory hearth, electrodes axially arranged through the Walls thereof, and means for causing the rotative movement of the hearth about its own axis, contemporaneously with 1ts osclllation about an axis substantiallyperpendicular to its axis.

10. In combination With a substantially cylindrical refractory hearth, axially arranged electrodes extending into the interior of said hearth from opposite sides thereof, and

a compounded support therefor adapted to contemporaneously oscillate the hearth about a plurality of axes substantially perpendicular to one another.

11. In anelectric arc furnace, in combination With a rotatable cylindrical hearth member provided With axially arranged electrodes, means for actuating the hearth about its axls, and means for contemporaneously imparting to said hearth a crosswise osci]la tory movement.

12. The combination of a substantially cylindrical rotatable hearth member, axially arranged electrodes capable of movement lengthwise of their axis, means for rotatiyely actuatingsaid hearth member, and means for contemporaneously imparting a transverse rocking movement" thereto. i

13. An electricarc furnace having, in combination with a substantially cylindrical refractory hearth, means for rotatably actuating the same about'anaxis variantly' approximating the horizontal, means for, at the same time, oscillating the same about an axis substantiallyperpendicular to its axis of rotation, and means for introducing and maintaining a high degree of temperature within said refractory hearth at its rotative center during its period of movement.

14. In an electric arc furnace, in combination with a substantially cylindrical refractory hearth, means for rotatively actuating the same about a movable axis Whose median position is substantially horizontal, means for introducing a high degree of temperature within said hearth above the proposed level of the metal to be treated therein, and means for rocking said hearth abou an axis substantially perpendicular toits axis of rota tion while its rotative movement is in progress. c a

15. An electric arc furnace having in combination a substantially cylindrical hearth member, electrodes axially arranged through the end walls thereof, and means for contemporaneously oscillating the hearth member about a plurality of axes substantially perpendicular to one another.

16. An electric arc furnace, having in combination with a refractory hearth member disposed for rotation about angularly vari ant axes, whose mean is substantially horizontal, means for rotatively actuating the same, means for imparting a transverse rocking movement thereto contemporaneously with its rotative movement, and means for introducing a high degree of heat adjacent the axial center of the hearth during its rotative period.

17. In an electric arc furnace the combination of a refractory cylindrical member disposed for rotation about axes substantially parallel with the horizontal, means for imparting thereto a transverse rocking movement, means for intermittently rotating the tory hearth, electrodes axially arranged" through the walls thereof, means forrotatively, actuating the same, means for intermittently reversing the direction of rotation of said cylindrical hearth, and means for imparting va transverse rocking movementth'ereto at the same timethat its rota-tive actuation is in progress.

19. An electrical arc furnace having in combination with a substantially cylindrical hearth member, axially arranged arc electrodes therein, means for contemporaneously oscillating said hearth member about a plurality of axes substantially perpendicular to one another, and means for automatically reversing the direction of each of such oscillatory movements at desired time intervals.

.HORACE W. GILLETT.

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