US1444980A - Electric furnace - Google Patents

Description

Feb. 13, 1923. 1,444,980..

' w. E. MOORE ET AL.

ELECTRIC FURNACE.

FILED SEPT. 5, 1919. 9 SHEETS-SHEET m.

[NvENToRs Feb. 13, 1923. 1,444,980.

w. E. MOORE ET AL.

ELECTRIC FURNACE.

FILED SEPT.5, 1919. 9 SHEETS'SHEET 2.

5 7 W Jaw w. E. MOORE ET AL.

ELECTRIC FURNACE.

FILED SEPT- 5, 1919. 9 SHEETSLSHEET 3.

Feb. 13, 1923. 1,444,980.

ATTORNEY Feb. 13, 1923.

w. E. MOORE ET AL ELECTRIC FURNACE.

9 SHEETSSHEET 4.

FlLE-D'SEPT 5; 1919.

//////////Z7llll/l/ A INVENTORS Feb. 13, 1923.

w. E. MOORE ET AL.

ELECTRIC FURNACE.

FILED SEPT- 5,1919- 9 SHEETS-SHEET 5.

Feb. 13, 1923. 1,444,980. w. E. MOORE ET AL.

ELECTRIC FURNACE.

FILED SEPT-5, 1919. 9 SHEETSSHEET &

1 BY J ATTORNEY Feb. 13, 1923.

W. E. MOORE ET AL.

ELECTRIC FURNACE.

FILED SEPT-5,1919. 9 SHEETSSHEET I.

[NVENTORS 6, m

Feb. 1 3, 1923. 1,444,980.

W. E. MOORE ET AL.

ELECTRIC FURNACE.

FILED SEPT. 5, I919. 9 SHEETS-SHEET a.

A T'TOR'NEY Feb. 13, 1923. 4 1,444,980. 4 w. E. MOORE ET AL.

ELECTRIC FURNACE.

FILED SEPT. 5, 1919. 9 SHEETS-SHEET 9,

"IN VENTOBS Patented l ef). 13', 1923.

UNITED STATES PATENT OFFICE.

WILLIAM E. MOORE, OF BEAVER, HERBERT FRANKLIN ALTER AND EDWARD AT LEE HANFF, OF PITTSBURGH, AND JOHN RAYMOND ECKLEY, OF NEW KENSINGTON, PENNSYLVANIA, AND FRANK WRIGHT, OF NEWPORT, KENTUCKY, ASSIGNORS TO PITTSBURGH ENGINEERING PORATION OF' PENNSYLVANIA.

WORKS, OF PITTSBURGH, PENNSYLVANIA, A COR:

ELECTRIC FURNACE.

Application filed September 5, 1919.

T 0 all whom it may concern:

Be it known that we, WILLIAM E. MOORE, a cltizen of the United States, and a resident of Beaver, county of Beaver, State of Pennsylvania, HERBERT FRANKLIN ALTER and EDWARD AT LEE HANFF, citizens of the United States, and residents of Pittsburgh, county of Allegheny, and State of Pennsyl- Vania, JOHN AYMOND ECKLEY, a citizen of the United States, and a resident of New Kensington, county of Westmoreland, and State of Pennsylvania, and FRANK WRIGHT, a citizen of the United States, and a resident of Newport, county of Campbell, and State of Kentucky, have invented a new and useful Improvement in Electric Furnaces, of which the following is a full, clear, and exact description.

Our invention relates to electric furnaces of the tilting or rockingtype, and it consists in the combinations, constructions and arrangements herein described and claimed.

.Heretofore, it has been customary to mount a furnace on rockers, extending longitudinally underneath the bottom of the furnace, which rockers run on horizontal tracks, also mounted underneath the furnace. There is frequent trouble with this arrangement, due to the accumulation of dust, dirt, slag and metal on the rocking surfaces and more particularly due to the fact that the furnace bottom occasionally cuts through and gums up the furnace rockers and tracks with molten steel. There is another difliculty due to the fact that the furnace rockers, when placed underneath the fur-' nace', resulti-n a very long forwardt'ravel of the s out when tapping, so thatthe craneman, w ile the furnace is being tapped, must rack his crane, in order to keep the ladle underneath the furnace spout.

An object of the present invention is to overcome-these diflicul'ties. To this end we mount heavy steel cast rockers or trunnion frames on the sides-of the furnace shell and and so proportion the radius of the rocking circle on the same, as to make the stream' I pou'rin from the spout impinge at substantially-t e same place in the receiving ladle Serial No. 321,851.

of the furnace rockers has been so much reduced and the rocking tracks are always clean makes thefurnace tilt so easily that even quite large furnaces are readily tilted by hand.

Heretofore, owing to the heavy work required by tilting, it has been customary to placetilting means in the pits underneath the furnace. These sometimes consist of a crank shaft connected by two pitmen up to the back end of the furnace shell: At other times the tilting means consist of hydraulic cylinders, placed in the same location and still other forms consist ofvertical swivelling screws, actuated by swivelling gear driven nuts placed underneath the backside of the furnace. These all require great depth of pits and foundations under the furnace, thereby increasing the cost and are all subject to rapid wear and tear, due to the accumulation of ash, slag, etc, as the motor and tilting gears are generally placed underneaththe working. floor level. They are also, in thisposition, especially objectionable when the furnace bottom cuts through and pours its contents of molten metal in and around the motor, worm gears,

pranks, screws, valves, etc, thus gumming them up and requiring great labor, delay and cost for repairs.

A further object of our invention is to provide a simple device for tilting the furnace, free from all troubles, due to dust,

dirt, slag, molten metal, etc., and all well above the. floor, making inspection easy and nace shell, engaging racks connected to the electrode arms, or in some'cases the motors are geared to vertical screws, which engage the electrode arms. This results in a great deal of complication in andjfaroun-d the furnace shell, which is specially objectionable, on account of the heat, dust and dirt To avoid these and other objectionable results we have provided. novel means v for operatingthe electrode arms, in which the winches are mounted in the-sub-station izvall, where they are protected from the dust and dirt, but are made readilv accessible. These means are fully described and claimed in divisional application No. 500,137, filed September 12, 1921. j

A further. object is. to provide" a pinrality of furnaces, having their transformers, charging doors, tapping spouts, etc., so arranged as to permit the placing of the furnaces closely together in a row, thereby effecting an-economj in space and permitting the furnaces to be conveniently charged.

for operating the furn 'ce doors consisting of levers and links which are so arranged as to cause the doors to move in a straight line,

means being provided for holding the doors. Y I of Figure 21,

in their open or their closed positions.

A further object is to provide an electrode;

gland made of cast iron which, if melted by the high heat of the furnace, will not 'i'njuriously contaminate the steel within the furnace. We also provide means fo eliminating the magnetic effect to which cast iron is subject. A further object is to provide a novel form of electl'ode clamp.

Other objects and advantages will appear 7 in the following specification, and the novel featuresof the invention will be particularly pointed out in the appended claims.

Our invention is illustrated in the accompanying drawings, forming part of this application, in which, 6

Figure 1 isa front 'viewof the furnace and the connections therefor,

Figure 2 is a side view of the furnace,

Figure 3 is a plan view,

Figure 4 is a plan view of an electrode arm, I -Fi re 5 is aside view of the arm shown in Figure 4,

F i re 6 is a section along the line 66 Figure 7 is a section along the line 77 of Figure 5, I

. I Figure 15 is a sectl further object is to rovide novel means e issa Figure '8 is a plan view of an electrode line 1313 of 'Figure 11,

Figure 14 is a front -'view of a furnace door sill, and cheekpieces for the sides of the door opening,

"on' along the line 15-45 of Figure 14,

Fig. 15 is a section on line 15-15 through one of the cheek pieces and bolts shown in Fig. 15; and is drawn to an enlarged scale to show the adjustable con-- struction more clearly,

Figure 16 is a plan view, showing a door opening and balancin means,

Fi re 17 is a si e. view ofthe door opening and balancing means,

Figure 18-'s a sile view of a counterweight, I

Figure 19 is a face view of the weight shown in Figure 18,

Figure 20 is a plan view of a column trunnion casting,

Figure 21 is a side View, of the casting shown in Figure 20,

. Figure-22 is a section along the line 22-22 of Figure 20,

Figure 23 is a section along the line 23-23 Figure 24 i armxcastingon the nace,

Figure shown in Figure 24,

Figure 26 is a section along 26-26 of Figure 24, and

Figu of Figure 25.

s a plan view of the trunnion opposite side of the furtlie line In carrying out our invention, we provide a suitable base 1, upon which, are mounted horizontal supports 2 and 3 for rockers or trunnion frames 4 and 5 respec- 25 is aside view of the casting re 27 is a section along the line 27-27- tively. The trunnions are mounted at the sides of the furnace body or crucible, so as to permit the furnace to tllt forwardly and backwardly. The means for tilting the furnace cons1ststof a hand wheel 6 at the end of a screw shaft 7 which is journalled in a swi ve1led bearing 8 on the floor column 9.

The screw shaft is provided with collars 10 for preventing endwise motion. Swivelled in an extension 11 of the trunnion frame 4 is a nut 12 which receives the threaded portion of the screw shaft 7. The tilting means, it will be noted, is well above the floor, making ready inspection and repair convenient, and being free from all troubles carried by the trunnion electrode arms are movable along the columns to adjust the arcs. For this pur- ,pose, we mount motor winches 1.6 inside the sub-station wall 17, where they are protected from heat, dust and dirt by the substation 18 and also by the removable screenor cover 19. .The motor winches 16 are connected with the arms 15 by cables 20 which pass underneath the floor 21 around sheave wheels 22, thence upwardly through the columns 14 to suitable sheaves 23, down around the sheaves 24 and are fastened to the sheave brackets 25. This greatly simplifies the furnace structure'and reduces the troubles, delays and costs of the ordinary structure.

As it is sometimes desirable to hoist the electrode arms when no power is available for operating the electrode winches, we also provide a hand crank gear 26, connected by sprockets 27 and chains 27 to the winches.

This has a crank shaft placed at convenient height and the chain 27 is made adjustably taut by eccentric handcrank shaft bearing 28 clamped in housing 2%, attached to lintel beams 30, built into the opening of the substation wall. The cranks 31, when swung ,backward, disengage the flattened head on Qgthe end of the sprocket shaft 27 so that the shaft may then revolve freely when turned by the motor without revolving the crank;

It has heretofore been customary with furnaces of the tilting type, tomount the pouring spout at 90 from the rocking axis of the furnace, and to mount the transformer back of and diametrically opposite the pouring spout. Owing to the travel of the furnace forward, vfiien rocked, totap,

and the radial height at which,the electrode cables are connected, this means very long secondary or electrode cables, and a great deal of slack must be provided. in the cables to allow the furnace to rock as required.

-Where the position of the transformer is back of the furnace and opposite the spout, it has been heretofore customary to place the charging doors in the-sides of the furnace, spaced 90 from the tapping spout. This has made it necessary to pour the slag out through the tapping spout of the furnace and into the ladle pit, which results in excessive heat in the ladle pit and delay in handling the ladle, due to the quantity of very hot slag which must be removed from the furnace only a short, time before tapping.

' The arrangement of the charging doors on the side precludes the possibility of feeding the furnaces eflicient as inour improved arrangement. According to our invention the several furnaces are arranged enables a slag p1t34 to be placed underneath I the charging door, covered by suitable floor plates into whichslag box 35 can be laced for conveniently receiving the slag when the furnace is rocked backward, without contaminating the ladle pit. This arrangement also permits of an underfloor slag.

conveying track running parallel to the line of furnaces in which slag cars may beused, as is convenient in larger plants.

In furnaces at present on the market, it is customary to mount the electrode arms to travel on a column-like frame work, consisting of I beams or channels standing vertically to one side of the furnace, and a beam or channel on each side of each of the electrode arms. There is then usually a mechanical electrode arm extending out over the center of the furnace, and the electrode clamp is mounted on theend of the arm and electrically insulated at its point of attachment to the arm. There is then usually applied an overhead electrical electrode arm for conducting the electricity out to the 'clamp. This is a highly objectionable construction, in that the insulation is immedi- .,ately over the openings in the roof, where it is subject to the smoke, flames and gases which leak out around the electrode glands; also due to the fact that the electrical currents must thus be carried between portions of the frame work of magnetic material, closed or partly magnetically closed, pro-. ducing high self induction and losses from the heavy alternating currents, and for the further reason that the arms, being stationary, so far as horizontal arrangement is concerned, greatly interfere with handling the furnace roof, when it must be removed.

1 In our furnace the electrode arms are carried on turned pipe columns 14 by means of sleeve-like cross heads 36, guided by antifriction rollers 37. These sleeves are held in their correct vertical plane by means of feathers 38, attached to'the columns, which elled to the right orleft to clear the furnace roof, or by means of additional feather-ways 40, see Fig. 4, when swung, may be lowered in their changed positions, so as to clear the furnace roof and make the clamps and arms accessible from the -fioor position; at the same time clearing the way for sling chains substantially to neutralize themagnetic induction. To avoid the difficulty due to insulationplaced at the clamp over the electrode openings, we construct the electrode arms of a box-like section, see Fig. 6, having channels 42 riveted at the top and bot tom' between copper bars 43 forming the sides of the arm, the whole being insulated as shown, by suitable lapped plates 44, washers 45, and bushings and insulating material back at the point of connection with the column traveling cross head 36, where the insulation is not over the heat, flame and smoke, as when placed over the electrode clamp, and is in a position to endure a minimum amount of break-downs and obstruction. I

There has heretofore been a great deal of difliculty with electrode clamps, which have usually been cast inone piece of solid metal conducting material.

with a split end having an opening, and adjustable by means of a right and left hand screw. These clamps have in some cases been water cooled, but the bending action, due to the wide range of motion necessary for opening'the clamp, soon causes the metal to crack or break, because of the large amount of adjustment necessary on account ofthe very irregular electrodes, of commercial grades.

To overcome this, we form a clamp of three parts,--a central portion 46, and wings 47 and 48 hinged to the central portion by heavy copper hinges 49. The wings are held together by means of a swing bolt 50 arranged to tighten by a wedge shaped key 51. The body of the renewable electrode clamp is cored-for water cooling, and is made of copper or similar highly electrically It is bifurcated as shown at 52 to allow some slight springing motion hen clamped to enable it to better fit the v a iiably sized electrodes; It is also provided with fingers 53, protruding from the hinge leaves which are in mesh between similar fingers 54 of the wings. The wings may be made of steel castings ribbed, and by means of these lcaved fingers, any heat developed in the wings is rapidly trans fcrred by conduction to the fingers and the to the water chamber.

The electric furnace doors, being subject to intense heat and requiring frequent opening and closing, are structures of great importance. l'leretofore, it has been customary to hang'the door on a lever, having formed on its door end a sector of sheave like or grooved section which carries a chain supporting the door. As there are necessarily leaks around the door, at certain periods of the operation, the chain is embraced by flamesgushing out from the furnace, which soften the metal of the chain links and cause the links to pull tight, in such manner as to interfere with the free and easy wdrkihg of the door.

To overcome these difficulties, we have.

devised a straight line lever motion shown in Figs. 16 to 19. This comprises a door lever 57, mounted in a fulcrum. stand 58, and engaging the links 59, which are attached t the door 60 by pins 61. The attachment point of these links to the door is caused to move substantially in a straight line by suitably proportioned compensating links 62 which engage the upper ends of the links or levers 59, the links 62 being suitably pivoted at 63 on the fulcrum stand 58. This door mechanism is counter-balanced by means of a weight 64, whose center f gravity 65 is placed above the center line of the lever 57, a sufiicient distance so that when the weight is up, the door is undercounter-balanced, in' its closed position, and will remain closed, and when the weight is down the door is overcounterbalanced and will remain open, thus avoiding the necessity for'additional devices to holdthe door open or closed.

The furnace doors are usually made of a metal, box-like casting which is open on its inner face'and is lined with refractory material, such as brick. Owing to the differential expansionbetween the door box and refractories, the ;-brick"are frequently loosened, so that when the furnace is tilted, they fall out of the door box into the furnace.

To avoid this, we have formed our door box 67, see Figs. 11,12 and 13, of a curved or'arch like form, so that when the refractory brick are set into the same, they arch themselves in and thus are restrained from falling out when the furnace, with the door,

is tilted through a wide angle.

Owing to the luminous flames which gush out around all openings in the furnace, due to the plenum or gas pressure, when dirty or oily scrap is bein melted, there is a great tendency to burntfie bottom edges ing. circle and are supp 68 of the door where the names lap the lower edge and then follow up closely along the surface of the metal doorbox.

To overcome this difficulty, we provide a rib or flange 69, which directs, the flame forward and away from the outer face of the door box, so that it does not creep up tightly against the face of, and overheat, the door box. This rib 69 also serves to cool the lower edge 68 of the box by conduction and radiation, and is still further cooled by other ribs 70 which joinit. We have found that this construction greatly reduces the wear and tear on the door casting. In 'order to make the door free to move in the vertical grooves 71 of cheek pieces 72, the ledges 73 on the vertical edges of the door bozg 67 are made to fit loosely therein.

The door sill 75 is arched downward, so that when lined with refractory brick it has a spout shape, guiding the stream, of

slag or steel to the center of the doorway. This door is still provided with wedge ribs 76 for holding the lower, edge of. the replaceable spout against the sill and with hooks 77 in which lugs 0n, the spout rest for holding the SPOlltllIl position. The adjustable cheekpieces 72 for the sides of the door openings are heavy castings made with a specially heavy transverse section along the door opening, to rapidly extract the heat from the inner edges and carry it out to the exterior cooling ribs 78 which tend to keep the heat of the cheek pieces within working limits. These cheek pieces 72 may be adjusted by loosening the bolts- 78" which pass through the horizontally elongated openings 78, and moving the cheek pieces into the desired position, and again tightening the bolts 78:. Hooks 79 are cast on the cheek ieces for supporting a rod placed cross t e door openings to supp'ortdthe hoe or hook when rabbling the furnace. l

The furnace shell is stoutly braced or reinforced around its to ed eor opening, by means of heavy angle section circumferential steel castings, which are s liced together to form a ring-like sti ener 80. The two rockers or trunnions have their upper edges formed as 0. art of the stiffeniiamented by lintels 81, see Fi 3, which, at the door openings are forme out over and away from the furnace shell, so' as to allow the door to pass between the lintel and the periphery'of the refractory lining of the vshell,-that is to.

say, the lintel carries the stifi'ening'stren h outside of the door, which permits the irnace shell over Jhe door to be cut away, thus preventing any weakening or buckling which would result due to heating of the furnace shell at the point immediately over the doors, where the flames gush out.

In Figs. 20 to 23, we have shown the details of the column trunnion casting 5. This has a top stiffening flange 83 which joins and is spliced onto the twolintel sections of the top stiffening ring. The

ings are grooved as at 84 to roll upon the A frame or track. The upper portion of casting 5 is cored at 85 and ribbed to receive the electrode arm uide columns 14 arranged to be ribbed and welded into position. The top flange of this casting .is drilled with holes 86 to be joined b riveted splice plates to the ends 81 of the intels.

Trunnion 4, (see Figs. 24 to 27) is ar ranged on its rocker face to receive a toothed sector 4 which engages with a toothed rack 2' on the A frame (Fig. 2) to prevent sliding on its track, due to the reaction of the tiltin screw swivelling nut 12, when tilting. his rack sector 1s not necessary on the column trunnion as the reaction from the tilting screw appears only on the tilting screw side trunnion.

Heretofore, it has been customary to use a water-cooled gland, surrounding the electrode at the opening where the same enters through the refractory roof. This is for the purpose of cooling the rooftc prevent the wear of' the refractories, cooling the electrode, to prevent its oxidation and reducing the escape of flame and the entrance of oxidizing gases.- It has been customary to make these glands of non-magnetic material, such as brass on ;broi1ze, for where magnetic material, such as iron or steel, has been used, there has 'resulted a high selfinduction, causing a loss of power, due to the magnetic circuit encircling the alternating current passing through the electrode. The use of copper or similar metals is highly expensive, and is also objectionable, forit occasionally happens, due to the cessation of water flow, that the gland melts and runs into the steel in the furnace, forming an injurious content in the steel, and spoiling the heat.

To overcome these difliculties, we make glands 88 of cast iron, as shown in lrlgs. 8 to 10, which, if it melts, does not in uriously contaminate the steel. To avoid the magnetic effect of the cast iron, we cast the same with an open space or gap 89, which may be filled with non-ma etic material, as for instance clay or as os, or may have cast therein such material as nickel or bronze. This gland is prov ded with a water passage 90 which is connected by pipe openings 91. It is provided with a large flan e 92 to cover the annular 0 between t e roof and the electrode, which must necessaril be lar r than the electrode, to allow or some of the electrode, due to irregularity. This flange, t has been found, frequently cracks, due to 70 lower edges or rocker sections of these casta the difierential expansion, incase the cooling water goes olf. To overcome this, this flange is heavily braced to the water chamber by braces 93 and is provided with inwardly extending slots 94 to allow for the diiferential expansion.

The buffer spring 96 (see Figures 1 and 5) is arranged to engage a pad or projection 97 attached to the .roof frames 80, so that the top of the electrode arm is caught by the spring, and the clamp end of'the arm prevented from coming into contact with the electrode gland, irrespective of the height of the roof or the extension of the same, due to heat. I

On the cross head 36 at its inner top edge are attached two horns or fingers 98 which project above the cross head, and are arranged to straddle and'engage the castor sheave 25,'mounted on top of column 14:, so that when the arm is still further raised until the feather-way 39 overlies the feather 38, and the arm is swung, the castor sheave will be automatically swung with it.

In Figures 1 and 3 we have shown the means by which the electrode arms are raised or lowered. A drum 99 is provided .for each cable 20, only one drum being shown. The cables 20, as stated before, pass underneath the floor 21. We provide a tunnel 39 for each cable. The cable is wrapped several times around the drum to obtain a friction bite and is passed over a pulley 100, see Figure 1, and supports a counterbalance weight 101. When the electrode arm has reached its uppermost limit of safe travel, the weight 101 will-rest on thefloor so that the cable 20 will be slack- 'ened and will lose its bite. thereby allowing the drum to revolve freely inside the coils of the cable without straining or breaking the hoisting mechanism. In likemanner, when the spring 96 engages the but tress 97, see Figure 1, the cable is slackened allowing the drum to revolve harmlessly.

In order to tightly against the door opening, in the closed position of the door, we provide door retaining lugs 73, see Figure 13,"which are arranged to be engaged by retaining strips 68 adjustablyattached to the lintels 81 so as to be adjusted toward or away from the door. The lower ends of the strips 68 are rounded so as to engage the door lugs 78 only in the closed position of the door. The

lower end of each of the strips 68 also forms a hook so that a bar laid between two strips 68' may be used as-a rabbling bar.

A divisionofdthis application was filed September 12th, 1921, Serial No. 500,137, in which the inventions relating to means for raising and lowering the furnace'electrodes, and for stopping the upward travel of said electrodes at certain predetermined limits,

keep the furnace door held make the stream issuing from the tapping spout travel in paths whichmeetthe receiv ing vessel at substantially the same point.

2. An electric furnace of the rocking type comprising a shell or crucible, trunnions attached to the sides of the shell, one of said trunnions having a swivelling nut, a tilting screw placed'above the tilting center of the furnace and arranged to engage the nut and means for operating the tilting screw.

3. An electric furnace of the rocking type comprising a shell, rocking trunnions attached to the shell on opposite sides thereof,

one of said trunnions having projections or eyes and electrode arm supporting columns attached to said projections or eyes.

4. An electric furnace of the rocking type comprising a shell, tilting trunnions attached to the sides of theshell, one of said trunnions having a toothed sector, a tilting screw for operating said last named trunnion. and stationary tracks for said trunnions. one of said tracks having-a rack arranged to be engaged by said toothed sector forresisting'the reaction from the tilting screw.

5. In an electric furnace, the combination of a furnace shell of cylindrical formation, having diametrically opposite doors, tilting trunnions or rockers placed on the sides thereof at right angles .to the doors and opposite to each other. one of said trunnions being formed to receive electrode arm guide columns and the other formed to receive an element of the tilting means.

cible, a counter-balanced door carried thereby, said door being arched outwardly and having an outwardly extending flame protecting flange or lip disposed at the lower edge of. the' door.

7. In an electric furnace, a shell or crucible'. a counter-balanced door carried'thereby said door being arched outwardly and having an outwardly extending flame protecting flange or lip disposed at the lower edge of the door and heat radiating ribs adjacent to said flange.

8. In an electric furnace, a vertically'slidable counter-balanced door, lifting links for said door, and compensating levers to give the lower ends of the lifting links a substantially straight line motion independently of any other guide means.

6. In an electric'fnrnace, a shell or cru-" 9. In an electric furnace, a verticall slidable .door, a lever for operating the cor, a

counter weight for the door the relative weights and positions of the door, lever and weight as a whole being so chosen that the center of gravity of the whole is substantially vertically above the fulcrum of the lever, thus producing an under-balanced condition when the door is closed and an over-balanced condition when the door is open.

10. In an electric furnace, a cylindrical column or support, an electrode arm mounted on s'aidcolumn to travel therealong, a feather carried by said column and arranged to enter a feather way in said electrode arm to keep the latter normally from rotating on the column, the electrode arm being arranged to clear the feather at the upper end of the column, thereby permitting it to be swung laterally and lowered.

11. In an electric furnace, an electrode arm of tubular or box like section, an electrode clamp carried by said arm at one end, a guide column, a crosshead sleeve for slidably securing the electrode arm to the column, and means disposed near the sleeve and remote from the heat for insulating the clamp from the sleeve.

at one end, an electrode arm gui e whereby self 12. In an electric furnace, an electrode arm, an electrode clamp carried b the arm column, a conductor carried by said electrode arm said conductor being split and carrie around the column on opposite sides of the same, wherebyself induction is diminished. 13. In an electric furnace, an electrode arm, an electrode clamp carried by the arm M10716 end, an electrode arm guide column, a conductor carried by said electrode arm, said conductor being split and carried around the column on opposite sides of the same, induction is diminished, and

means for attaching electrical conductors to the split end of said conductor.

14;. In an electric furnace of the rocking type, the combination of diametrically opposite ltapping and charging doors located at 90 to the rocking axis of the furnace,-

said furnace being a.dated to tilt backward for slagging and forward for tapping and a transformer placed to one side of and at about 90 to the line of doors.

15. In an electric furnace of'the arcing electrode type, a renewable electrode holder, b0 comprising a, bifurcated body,

having water circulating chambers in said. body, with hinged joint sections and adjustable clamp wings.

16. In an electric furnace of the arcing electrode type, an electrode clamp eomprising a. water cooled body having a series of projecting fingers on each side thereof, and

a pair of clamping wings having arranged to enter between the of the.

body and pins for hinging the fingers of the wings to thoseof the body.-.

I 17. In an electric furnace. a vertically slidable door, adjustable cheek pieces guiding said door, loosely" fitting guide flanges on the door arranged to engage said cheek pieces, and stop pieces carried by said cheek pieces. and arranged to be engaged by a portion of the door for forcing the latter against its seat in the closed position of the door.

18. In an electric furnace of the tilting type, the combination of a cylindrical shell with curved bottom, and having door openings, stifl'eners around the top ofthe shell. said stifi'en'ers being bent or bowed away from the furnace shell over the door openings, and the shell being cut away over the door openings.

19. In an electric furnace, the combination of a guide column, a vertically 'slidable electrode arm of tubular or box-like structure having conductive sides, and a renewable electrode clamp set into the outer end of said arm, the conductive-sides of said arm being divided and carried around the column to the back side, the sides of said arm projecting' backwardly around the column and supported by said cross head, a guide column for said .cross head, andirollers carried by said cross head and arranged to bearon said guide column.

21. In an electric furnace, a. vertically slidable cross head of sleeve-like construction, an electrode arm insulated from. and supported by said cross head, a guide column for said cross-head, rollers carried by said cross:head and arranged to bear on said guide column, and-means for normally preventing the lateral rotation ofsaid cross head with respect to said guide column.

22. In an electric furnace, a water cooled electrode clamp comprising a central portion, wings hinged to said central portion, and means for adjustabl damping the wings to the electrode, said means compris-' ing a swing bolt carriedaby one of said wings and a Wedge carried by! the other wing and arranged to be engaged by said swing for 23. In an electric furnace of the rocking type, the combination of an open top shell, lined with refractory material, said shell .having vertically slidable doors, a stiffener around the top edge of the shell and attached thereto, the (stiffener being bowed or bent out and away ,from the furnace shell periphery, thereby allowing the doors to tory lining of the shell.

slide between the stiffener and the refrac-' 24. T he combination with an electric furnace having a roof provided, with anopening therein, of a water cooled electrode slidable on said support, and a spring bufl'er carried by the armand arranged to engage gland comprising a split metal'ring having near the bottom of said ring, said flange being )rovided with radial slots. 26'. n an, electric furnace of type, 9 support, an electrode hearing arm ing and lowering said arm arranged to pass over said sheaves, said cables the tilting a portion of the furnace for cushioning the arm at the limit ofits movement in one direction. I

27 In an electric furnaceof the tilting type, a support, an electrode-bearing arm slidable on said support, a rotatable sheave bracket carried by said support; sheaves carriedby the bracket, and cables for raisbeing secured to said electrode-bearing arm. a

. WILLIAM E. MOORE.

HERBERT FRANKLIN ALTER. EDWARD AT'LEE HANFF. JOHN RAYMOND .EOKLEY. FRANK WRIGHT.

DISCLIAIMER 1,444,980'.' William E. Moore, Beaver; Herbert Franklin Alter and Edward At Lee Hanfi, Pittsburgh; and John Raymond Eclcley, New Kensington, Pa.; and

\Frank Wright, Newport, Ky.- ELECTRIC FURNACE.

13, 1923. Research Corporation.

Patent dated February A Disclaimer filed January 14, 1939, by the assignee, Pittsburgh Hereby enters this disclaimer to claims 11, 12," 13, 14, 17, 18, 19, 2t), 21, 23, and

27 of said patent.

0 7mm Gazette, Febiam r, 1 989.

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