US1378972A - Electric furnace - Google Patents

Description

W. E. MOORE.

ELECTRIC FURNACE.

APPLICATION FILED JULY 18. 1919.

"1,378,972. ted May 24, 1921.

3 SHEETSSHEET l.

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WE MOORE ATTORNEY W. E. MOORE. ELEQTRIC'FURNACE. APPLICATION FILED JULY 18, 1919.

Patented May 24,1921.

3 SHEETS-SHEET 3 IN VEN TOR. IV E MOORE ATTORNEY UNITED STATE WILLIAM E. MOORE, OF MILWAUKEE, WISCONSIN.

ELECTRIC FURNACE.

Application filed July 18, 1919. Serial No. 311,802.

1 '0 all whom it may concern Be it known that I, lVILLIAM E. MOORE, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented new and useful Improvements in Electric Furnaces, of which the following is a specification.

This invention relates to electric furnaces, especially those designed to melt non-ferrous metal mixtures, such as brass or zinc, and it consists in the combinations, constructions and arrangementsherein described and claimed.

Heretofore it has generally been considered quite unsatisfactory to melt non-ferrous metal mixtures, especially those high in volatile content, such as zinc or yellow brass, in an arc type electric furnace, for the reason that. the metal loss is quite high, due to the volatilization incident to the localized application of very high temperatures generated by the arc. To overcome this difficulty, electric furnace brass melters have resorted to the expedient of resistance heaters, lying alongside of the chamber which contains the pool of metal, or bath, so that the metal is melted only by indirector reflected heat, which is softened and distributed to such an extent as to reduce vo1atilization losses materially.

Another means has been to make the furnace in the shape of a rotating or rocking 4 with an arc sprung approximately in the.

- center of the furnace or crucible chamber and the power .conducted out through the electrode in the opposite end, electrodes being placed substantially in the axis of the furnace and generally rocking or revolving with, though sometimes fixed and the furnace rocking or revolving about them.

The actionof the revolving or rocking furnace is to distribute the metal and keep it tumbling over, so that no one part or piece is unduly heated to the extent of causing high volatilization losses.

The tumbling metal, or when it becomes molten, the washing metal, washes the interior circumference of the crucible chamber and prevents excessive localization of the heat therein. In such furnaces the. tapping spout and doors are usually provided at the ends or on the periphery in the middle,

and the furnace or crucible generally rocks or rotates on a substantially horizontal axis mounted on four or more rollers of the antifriction roller type.

In some cases the furnace is caused to rock, first in' one direction and then in the other to some suitable angle, usually less than 300, thus producing the same effect in the way of tumbling the metal and washing the refractory walls of the furnace, and distributing the heat. In such furnaces the charging door and tapping spout can be affixed without difficulty to the periphery of the furnace near its center and the rocking motion is so adjusted that the door is not submerged by the metal during the rock of the furnace.

Such furnaces have generally been difficult to operate, due to the excessive amount of power required for their operation due to large wall areas and the excessive wear of refractories due to the severe tumbling action of the metal. There has also been great difliculty with the electrodes,'due to breakages caused by unmolten metal sticking to the furnace shell and falling, thereby necessitating an unusually large drum, due to the concentric location of electrodes, and due to the tendency of the volatile elements to escape around the electrode openin s and there condensing and freezing tig t the electrodes into the furnace ends hindering or inhibiting the proper adjustment of the electrodes.

Another difficulty with such furnaces that have heretofore been manufactured, has been found due to the fact that the furnace crucible itself is not portable, having attached to it so much of the rocking gear and electrode fixtures. and being of such cumbersome size and shape that it is impracticable to lift it off by a crane, or to transport it over the foundry floor where the metal may be tapped directly from the furnace to the molds. This inability to transport the furnace makes it essential to tap the metal from the furnace into a ladle before teeming into the molds, and there s always a high metal loss by volatilization during the tapping operation, which is still further intensified, due to the fact that the metal in being tapped from the furnace into the ladle cools rapidly and in order to have the proper temperature when teemed into the molds, it 'must be superheated to a higher degree before being tapped from the furnace, all of which tends to increase the volatilization of the metal.

There is also diflicultyin charging such furnaces due to the small door which is necessary to properly clear the electrodes and to allow a sufficient angle of rotation or rock. There is also a vltal objection to these furnaces by reason of the location .of the axial electrodes, which makes essential the use of single phase current,

. An object of the present invention is to provide an electric arc furnace in which the wear of refractories is largely eliminated, the danger of breaking the electrodes is obviated, and in which the adjustment of the electrodes is easily effected.

A further object is to provide a portable furnace of the type described in which the furnace crucible can be lifted from the operating gear and transported by crane or similar device directly to the molds.

A further object is to provide a furnace whose construction permits the use of polyphase, as well'as single phase, current.

Other objects and advantages will appear in the following specification, and the novel features of the invention will be particularly pointed out in the appended claims.

My invention is illustrated in the accompanying drawings, forming part of this application, in which:

Figure 1 is a front elevation of the device,

'Fig. 2 is a sectional detail of a ball bearing,

Fig. 3 is a plan View of an electrode gland,

Fig. 4 is a section on the line 44 of Fig. 3,

Fig.5 is an end view of thefurnace and operating gear, a portion of the furnace being shown in section,

Fig. 6 is a section through a furnace body having two electrodes,

Fig. 7 is a diagrammatic view of a modified form of furnace having three electrodes,

Fig. 8'is a plan view of the form shown in Figs. 1 and 5, and

Figs. 9, 10 and 11 are detail views of an electrode column bracket.

In carrying out my invention, I provide a base 1 of any suitable sort, upon which is mounted an A-frame 2, arranged to receive the trunnion 3 of a swinging base 4. The

latter may be swung or tilted by means of a handle 5 pivoted at 6 to the trunnion and being provided with a locking segment 7 adapted to hold the base in its adjusted positions. The opposite end of the base is provided with a hanger 8 pivotally mounted on a hollow boss 9 carried by the adjacent A- frame 10. A motor M- is carried by a bracket 11 secured to the A-frame 10 and the motor shaft 12 extends through the boss 9 and is provided with a worm 13, (see Fig. 8)

arranged to mesh with a worm wheelll inclosed in a housing 15 which forms a part or continuation of the hanger 8. A shaft 16, on which the worm wheel 14 is mounted, extends downward and is provided at its bottom with a gear 17 which meshes with a gear 18 cast integrally with a cup 19 arranged to receive the crucible 20 of the furnace, the crucible being removably secured by means of wedges K. The cup 19 has its bottom provided with a circular groove arranged to register with a similar groove in the base 4 to receive the bearing balls 21 (see Fig. 2). The cup is retained in position 'by means of a bolt 22, but may rotate by means of a thrust ball bearing 23.

The furnace shell or crucible is lined with refractory material 24 in the usual way, eX- cept that at a certain zone, corresponding to-the arcing zone of the electrode, a zone of conducting brick 25 as, for instance, graphite or carbon brick, may be used, on to which the electrodes 26 may arc, as, for instance, 7, when it is desirable to connect one each of and each of the electrodes respectively to the 'other of the remaining two of the three phases. Sometimes'it is desirable to use three inclined electrodes, as, shown at 26 in uFig. 7, in which case one electrode may be the common return of the two phase circuit, or each may be respectively connected to one of three phases. Fig. 7 shows top view of such electrode arrangement.

In Fig. 6 is shown a sectional view along the plane of the axis of the two electrodes, showing them as arcing down to the conductive zone of brick. The are is preferably of the free burning type, that is, not in contact with the furnace charge, although in some cases the arc may be to the metal charge when desirable.

The electrodes are held by means of clamps 27 of any suitable and usual form, shown here as a split clamp. These ma be either plain or water jacketed. ese clamps are insulated from their supporting carriers by any suitable orwell known means, as for instance by clamping around insulating mica sleeves 28, and having suitable lugs or provision for attachment of the electrical wires or cables as at 29. I

The electrode'arms are carried on square columns 30 on one side of which is attached a spur gear rack 31, into which meshes the worm cut on the end of an inclined crank shaft 32, journaled in a housing 32 so that by rotating said crank shaft, the worm en- 130 gages the rack andmoves the arm slidably up or down its supporting column 30 for the proper adjustment of the electrode and its arc.

Each column 30 is held in a universal clamp 33, by means of which the column may be swung in either of two planes, so, as to give the electrode any desirable arcing angle when shifted about its center which is formed at the axis of a water cooled gland 34 forming a seal, where the electrode enters through the furnace roof into the crucible. Thus the arm may be located at any convenient height or in any position necessary to clear the tumbling scrap when the furnace shell is rotated about its axis. However, thisis' an adjustment not frequently required and having been set for one class of operation has rarely to be changed.

The gland 34 is formed with a water chamber 35, taking its water circulation from pipe openings 36, with a central bore 37 for the freepassage of the electrodes, the bore being grooved to form a labyrinth packing, the upper surface of the gland being slightly cupped to hold a mud seal or other packing when required. With a gland of this character there has generally been difficulty in melting highly volatile metals, due to the effect of thevapor condensing on the electrode opening, so as to jam the electrode. To overcome this a groove 38 near the bottom of the electrode opening is connected with pipe opening 39, to which a light current of gas is blown of sufiic'ient volume to prevent the exit of the gases from furnace. In some cases it is preferable to feed this groove with a volatile mixture, as for instance with crude oil, which being volatilized, forms a non-oxidizing vapor of sufficient volume to prevent the exit of the metallic vapors from the furnace. The lower surface of th gland is made spherical in shapeso as to fit the depression or seat 40 in the refractory and insulating roof 41 of furnace, to the purpose that the electrodes, passing down through openings in such roof, may be rocked in the manner heretofore described to any suitable angle, and will seal their openings.

The glands are piped by means of insulating hose connections to a suitable water supply (not shown) to prevent them from overheating or melting.

The furnace crucible is provided with any suitable tapping spout, as at 42, or it may be lippoured over the top when desired. llt is also provided with trunnions 43, which may be engaged by a suitable crane, hook-or forked truck and thus readily transported to the molds. There it may be tilted by means of a lever entering one of the sockets 44, attached to the furnace shell for convenient tipping of the furnace.

It will be understood that the furnace lar material which adjusts itself to the annular ring 46, thus more nearly forming a gas tight joint. 7

Where a single electrode using a single phase or direct current, arcing direct to conductive lining of crucible is used, the support of column 30, held by universal clamp 33, may be made direct to a post or column 49, carried by the base 4, and thus the entire roof 41 may be allowed to revolve with the furnace shell about the electrode 26 and gland 31, placed in its center of rotation. This arrangement is not shown on the drawings, but is obvious from the description.

It will, of course, be obvious that when two or more electrodes are employed, the adjustable bracket 33, Figs. 9, 10, and 11, may be supported direct on column 49, instead of being attached to the roof ring 11, as in Fig. 5, and'that such electrodes may be lifted axially out of the glands when necessary to swing the roof.

The spout 42 is closed during the melting operation by a refractory plug asof mud or brick.

The roof ring 45 is, preferably held by means of a swinging adjustable carrier 48 (see Fig. 5), which is slidably mounted upon the cylindrical column 49, above mentioned, rigidly carried by the base plate upon which the furnace cup rotates. The carrier 48 is bored to a neat finish on column 49 and in the melting position of the furnace has a lug or tooth shaped projection 50,

engaging a corresponding depression in an adjustable collar 51, to hold the roof and electrode in proper concentric relationship to the rotating furnace.

The carrier 48 is arranged to be lifted by means of a lever 52, to which are attached links 53, which lever may be thrown from a vertical into a horizontal position as shown by-dotted lines, when the point of attachment of the links to the lever, (shown at 53 in Fig. 5) passes over the center of the pivotal point 55 of the lever, and this holds the lever in horizontal position. In the horizontal position the links 53 lift the furnace roof clear of the shell, when it may be swung to one side and held thereby a projection 54 on the bottom edge of the lever entering through a slot in fulcrum cap 55, where it engages a depression or keyway 56, formed in the top of column 49, and thus holds the roof fixed to one side and clear of the furnace, as for instance when charging the furnace, or when the furnace crucible is being lifted by trunnions 43, after the metal has been made molten and is ready for pouring. ln this operation it is preferable to cover the furnace with an insulating cover, as for instance, a circular metal cover with flange projecting into annular space 47, the metal covering being lined with some insulating material as with asbestos, for preventing a rapid radiation of the heat from the furnace and metal during its transportation and pouring.

The roof ring 45 engages hooks 5? formed on carrier 48 and is adjusted for concentricity with the rotation of the furnace by means of set screws 58, so that it may be adjusted for concentricity with the rotation of the furnace shell and also parallel to the plane of rotation. At the same time it is readily detachable for renewing the refractory roof ll. The roof ring 45, with electrode supports 30, may be rotated to an angle most suitable to make the electrodes clear the tumbling furnace charge.

in operation, the furnace is filled while in a vertical position. Before filling, the roof must, of course, be swung to one side, and in order to do this, it is necessary to raise the electrodes by means of the worm and rack arrangement, until their ends are high enough to clear the edge of the crucible after the lever 52 has been brought to a horizontal position. The crucible is filled only to a suitable height, generally about two-thirds full of metal to be melted. T he roof is then swung to a working position, the arc struck, while the crucible is being slowly rotated by means of the motor M in counter-clock-wise direction, shown by the arrow in Fig. 8, so that the scrap, when the furnace is tilted to some suitable angle, as in Fig. 5, is continually tumbling down this angle of repose, so as to clear the electrodes 26 when set at a proper angle. The electrodes should arc well down into the furnace, but still above the path of the tumbling scrap, where they are free from breakage and where heat of the arc is evenly distributed over the tumbling surface of the scrap.

At the same time, the interior crucible surface, against which the arcs heat is most intense, is being metal and cooled to the temperature of the metal by the rocking or rotation of the furnace. When the metal has become molten the same rotation or rocking produces a proper mixing of the constituents.

When the proper degree of heat has been obtained the crucible may be rotated so that the spout is in the position shown in Fig. 1, when the furnace may be tilted and tapped into the molds or ladles, or it may be rocked brought into contact with the or rocked at various angles and while the structure herein described is suitahle for many purposes l do not wish to confine myself to the details of the structure shown, for

it is obvious that this structure may be changed into the forms where the conditions warrant it.

Wherever the word rotation is used or rotary, it is to be understood that the furnace may also be given a rocking motion by the usual and well known means. The swinging roof construction may be varied to suit the o crating conditions. it is also un- L derstood t at it may be applied and used on a furnace which is not in rotation or in rocking motion, as for instance when the furnace is used for melting steel or nonvolatile metals, the rotary or rocking motion might be eliminated altogether.

' I claim:

1. lln an arc type electric furnace, the comb nation with a rotary furnace shell or cruc1ble, of means for adjusting the inclination of the axis of rotation.

2. In an arc type electric furnace, the comblnation with a tiltable rotary cup or holder, of a removable crucible mounted in said holder, and means for detachably securing thecrucible in position against displacement by the tilting of said holder.

3. in an arc type electric furnace, the combmation with a rotary cup or holder, of means for adjusting the inclination of the axis of rotation of said holder, and a crucible .removably seated therein.

tfln an arc type electric furnace, the combination with a rotary cup or holder, of a crucible removably mounted in said holder, sa1d crucible having trunnions by which it may be lifted and transported, and about WhlCll it may be rocked for pouring.

5, In an electric furnace, thecombination wlth a rotary crucible, turning on an axis which may be inclined to any desired degree fromthe vertical, of one or more electrodes entermg through the roof of the crucible.

6. In an electric furnace, the combination w1th a crucible of a removable roof therefor, and means for lifting said roof and swingmg it to one side.

In an electric furnace of the arc type, the combination with a crucible, of a removable roof therefor, electrodes carried by and passing through said roof, and means for elevating and swinging to one side the roof, carrying with it the electrodes.

8. In an electric furnace of the arc type, the combination with a crucible, of a removable roof therefor, electrodes passing through the roof, electrode adjusting gear carried by said roof, and means for swinging to one side the roof with the electrodes and adjusting gear.

9. In an electric furnace, a crucible, an electrode entering such crucible, and fluid means for preventing the escape of furnace gases around the electrode. I

10. In an electric furnace, a crucible, an electrode entering such crucible, a packing gland surrounding the electrode and having an interior annular chamber, and means for supplying fluid to said chamber to prevent the escape of furnace gases around the electrode. 1

11. In an arc type electric furnace, the combination with an electrode, of a supporting column therefor, and means for adjusting said column in any direction to vary the angular relation of said electrode, and for holdin it in adjusted position.

12. I n an arc-type electric furnace, the combination with the crucible, of a removable roof therefor, an electrode entering through the roof, a supporting column for said electrode carried by the roof, and means for adjusting said column in any directionto vary the angular relation of said electrode to the roof.

13. In an electric furnace, having a crucible of cylindrical shape or circular section, provided with conductive walls, the combination with a roof, and electrodes entering through the roof, of means for varying the inclination of said electrodes to the plane of the roof, so that the arc may be struck between the electrodes themselves or between one or more of the electrodes and the conductive wall of the furnace.

14. In an electric furnace, having a crucible of cylindrical shape or circular section, provided with conductive walls, the combination with a roof, and electrodes entering through the roof, of means for varying the inclination of said electrodes to the plane of the roof, so that the arc may be struck between the electrodes themselves or between one or more ofthe electrodes and the conductive wall of the furnace, means for rotating said cylindrical crucible about its axis, and means for varying the inclination of such. axis.

'15. In an electric furnace, a cylindrical crucible, refractory lining portions for said crucible, and a Zone of conducting material extending around the crucible and disposed between said refractory lining portions.

16. In an electric arc type furnace, a cylindrical crucible, a refractory lining for portions of said crucible, a zone of conducting material disposed between said refractory lining portions, a roof, and electrodes carried by the roof and arranged to are to said conducting zone.

17. In an electric arc type furnace, a tiltable support, a rotary crucible carried by said tiltable support, means for rotating the crucible, a roof for saidcrucible, through which roof one or more electrodes enter at an angle adjustable relative to the plane of the roof, together with means for striking the are at any desired point in the plane of rotation of said crucible.

18. In an arc type electric furnace, the combination with a rotary crucible having a removable roof, of means for supporting said roof to swing about an axis parallel with the axis of rotation of the crucible, and means for lifting and swinging the furnace roof about its axis, and for holding it either in the closed or open position.

19. In an arc type electric furnace, the combination with a rotary crucible having a removable roof, of means for varying the inclination of the axis of rotation thereof, and means for supporting said roof to swing about an axis at all times parallel with the axis of rotation of the crucible.

20. In an arc type electric furnace, the

combination with a rotary crucible having a removable roof, of means for pivotally supporting said roof to swing laterally of the furnace into open and closed positions, means for varying the inclination of the axis of rotation of the crucible, and means for maintaining the pivotal axis of the roof always parallel with the axis of rotation of the crucible.

21. The combination with an electric arc type furnace, of a swinging base on which it is mounted, means for rocking such base to tilt the furnace, a post rigid with said base, a removable roof for the furnace supported by said post, and means for lifting and swinging the roof about such post.

22. The combination with an electric arc type furnace, of trunnions on which it is supported, means for tilting the furnace about such trunnions, 'a post tiltable with the furnace, a removable roof for the fur-..

nace carried by said post, and means for swinging the roof around said post to clear the furnace.

23. In an arc type electric furnace, the combination with a crucible, of a holder in which the crucible is seated, a tilting frame on which the holder is rotatably mounted, trunnions on which said frame is supported, and means for rotating the holder comprising a shaft extending through the axis of a trunnion.

24:. In an electric furnace of the tilting type, the combination with a base, of a crucible rotatably mounted thereon, trunnions on. which said base may swing, and

means for rotating said crucible, said means comprising a worm disposed on a fixed horizontal axis, and a worm wheel associated therewith and tiltable with said base.

' 25. In an electric furnace of the tilting type, the combination with a base, of a crucible rotatably mounted thereon, trunnions on which said base may swing, and means for rotating said crucible, said means comprising a worm mounted concentric with one of said trunnions, and a worm wheel tiltable with said base and having a shaft extending in a direction at right angles to the tilting axis.

26. The combination with an electric fur? nace, of a swinging base on which it is mounted, trunnions on which said base is Supported located at the sides of the furnace above the bottom thereof, and means for tilting said base and furnace about such trunnions. v

27. In an electricv arc type furnace, a crucible, a top therefor, electrodes carried by and arranged to project through the top into the interior of the crucible, means for tilting the crucible at an angle to the vertical, and means for rotating the crucible in its tilted position.

28. In an electric arc type furnace, a base, a support pivoted to the base, a crucible removably carried by said support and arranged to be tilted with said support to an inclined position, and means for rotating the crucible on the support in any position of the latter.

29; In an electric arc type furnace, abase,

'a support pivotally mounted on said baseso as to,tilt, a crucible removably carried by said support, means for securing said crucible to said support, a removable roof for said crucible, and an electrode carriedby the roof and arranged to project into said crucible.

30. In an electric arc type furnace, abase, a pivoted support carried by the base, a crucible carried by said support, means for rotating-the crucible on the support, and

navaera means for tilting the support and for holding it in its tilted position.

31. In an electric arc type furnace, a base, a swinging support carried by said base, a removable crucible carried by said support, a removable roof or cover for said crucible, electrodes carried by the roof and arranged to project into said crucible, and means for raising the roof and for. swinging it and the electrodes clear of said crucible.

32. lln an electric arc type furnace, a base, a swinging support carried by said base, a removable crucible carried by said support, a removable roof or cover for the crucible carried by said support, electrodes carried by the roof and arranged to project into said crucible,means for raising the roof and for swinging it and the electrodes clear of said crucible, and means for adjusting the electrodes with respect to the roof to bring them to the desired position within the crucible.

33. lln an electric arc type furnace, a base, a swinging support carried by said base, a crucible mounted on said support, a removable roof or cover for the crucible carried by said support, electrodes carried by the roof and arranged to project into said crucible, means for raising the roof and for swinging it and the electrodes clear of said crucible, and means for moving the electrodes axially in a direction at an angle to the plane of the'roof.

34. In an electric arc type furnace, a base,

a swinging support carried by said base, a

removable crucible carried. by said support, a removable roof or cover for the crucible carried by said support, electrodes carried by the roof and arranged to project into said crucible, means for raising the roof I and for swinging it and the electrodes clear of said crucible, means for moving the electrodes axially in a direction at an angle to the plane of the roof, and means for varying such angle,

WILLIAM E. Moons,

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