US2116202A - Electric smelting furnace cover - Google Patents

Description

May 3, 1938. P. HONEGGER ELECTRIC SMELTING FURNACE COVER Filed Feb. 13, 1956 Patented May 3, 1938 .UNITED STATES PATENT OFFICE l Sulzer Freres, Societe Anonyme,

Switzerland winterthur:

Appneaun February' 13, 193s, sensi No. 63,304 In Switzerland February 18, 1935 3Clalms.

tric arc Yfurnaces in which the construction is such that the expansion and contraction of the furnace cover cannot crowd upon or otherwise interfere with the electrode or with its movement.

Another object is to provide means in connection with the cover of a furnace for elastically and yieldingly holding the members of which the cover is formed. vAnother object is to provide in connection with a furnace cover means for automatically compensating for temperature variations in the'material' of which the cover is formed.

Another object is to provide in connection with a furnace cover automatic means effective upon expansion of the cover, due to increase of tem- `perature, to prevent displacement or shifting of the cover parts so as to/cause jamming of the 5 electrode.

Other objects will appear from time to time in the specification and claims.

, The invention isillustrated more or less diagrammatically in the accompanying drawing, wherein:

Figure 1 is a generally vertical section through one form of furnace to which the cover canbe applied; f

Figure 2 is a top plan view with parts in section, illustrating a portion of the top or upper surface of the cover in addition to a section through the supporting structure for the cover,

taken generally at line 2-2 of Figure 1;

Figure 3 is an enlarged sectional detail showing a modified form of the yielding arch supporting structure.

Like parts are designated by like characters throughout the specification and drawing.

I is a furnace supporting` structure of any 5 suitable form whose details form no essential part of the present invention. As shown, the

furnace comprises a brickwork structure 2, reinforced by members 3 and having a lining por- V'tion 4 I't is to be understood .that this inven- So. tion is not limited to any particular furnace nor toanyparticular details-fof furnace construction t may be applied to almost any furnace and "to, urnace of almost any shape although in the lparticular form herewith shown it is primarilyssfadapted forappiication to an electric arc fur- (Cl. 1H)

nace in which a plurality of electrodes is positioned to extend through the cover into the interior of the furnace. Y

In the particular form. here shown there are three electrodes i each of which is supported on 5 an arm 6 which is secured to a moving support p I mounted within the channel guides 8 and carrying rollers 9 which contact the members 8. At its outer end each arm is secured to a piston rod II) which carries at its other end a piston, not 10 shown, lying within a cylinder II.

A servo motor or any other desired mechanism not here shown Ais eiective to vary the pressure within the cylinder II in response to variations in the current intensity, so that the 15 distance of the electrodes from the metal within the furnace is varied and in this way the length of the electric arc is adjusted or varied.

A cable I2, one foreach electrode 5, furnishes current to the electrode to which it is attached. The cable vis preferably flexible and secured to a conductor-'i3 which is mounted upon and moves with the arm I. As in the case of the furnace itself, the electrode details just described are not essential to the invention and other electrodes or electrode mountings and adjustments, might equally well be used with the cover of the present invention. In fact, means other than electrodes for heating the furnace might be used. j 30 'I'he furnace cover comprises a supporting ring I4.' 'Ihis ring conforms generally to the shape of the furnace, whatever shape that may be, and is preferably of generally I-shaped cross section, thus providing an upper and a lower flange, gen- 35 erally horizontal, and a generally vertical web joining them. This web is pierced to provide convenient passage for pins I5 of which a number are positioned about the supporting ring I4.

Fach pin has a collar I6 which serves to limit its 40 inward movement through the web of the ring I4. A spring II is positioned about each pin. Each such spring bears at one end against coller I8 on its particular pin I5, and at its other end bears `against a supporting member I8, formedasa part of or secured to the supporting ring Il. The springs thus normally tend to urge i the pins inward tothe limit of their movement,

that is to say, until the collars II are in contact with the generally vertical web of the supporting ring Il. The Inns are shown in this position in Figures 1 and 2,

Positioned inside of the supporting ring I4 and engaged or supported by the inner ends of the pins I5 are a plurality of preferably segmental 55 members I9. These segmental members serve as the support for the several stones or pieces of which the cover of the furnace is formed. These may be of any suitable refractory material, for instance, silica-brick. They are indicated generally by the numeral 2U. It is to be understood that they may be of any desired shape and arrangement -and the particular arrangement shown comprises merely one example. The furnace cover is provided with a perforation or opening 2I for each electrode. In the particular form shown herewith there are three electrodes. For packing or sealing, and in order to reduce the loss of heat, a ring 22 may be positioned upon the cover and about each electrode 5. As shown this ring is hollow and arranged to receive a cooling liquid from any suitable source through the conduit 23.

In Figure 3 a modified form for mounting the segments I9 is shown. In this form, instead of springs, hydraulic or other fluid pressure may be used. Thus each of the segments I9 is mounted on or in contact with a piston rod 24 which has on its opposite end a piston 25. This piston is positioned within a cylinder 26, which receives pressure fluid from any desired source and of any desired nature through a conduit 21. It is obvious that the form of Figure 3 comprises therefore a fluid pressure device which accomplishes the same purpose and permits the same conditions of operation as those accomplished and permitted by the structure of Figures 1 and 2. Each of these forms has the common purpose of providing a yielding, iiexible or elastic mounting for the furnace cover.

It will be realized that whereas I have herewith shown and described a practical operative device, nevertheless many changes might be made in the size, shape, number and disposition of parts without departing from the spirit of the invention and I wish, therefore, that my showing be taken as in a sense diagrammatic.

In particular the cover might have any desired plan, round, polygonal or otherwise. While the supporting ring I4 has been shown as a unit, obviously vit might be made of sections, rigidly positionedor any other generally :fixed mounting might be provided about the edge of the cover as a base and support for the segments I9.

The use and operation of my invention are as follows:

As above noted, the parts are shown in Figures 1 and 2 in the position which they occupy when the furnace is not heated, or at least when it has not been heated sufdciently to cause any effective expansion of the stones or bricks of the cover. Upon a sufficient heating of the furnace the cover is, of course, heated, the stones or other pieces of which the cover is made expand and the segments I9 are, or tend to be, pressed outwardly. Since the segments I 9 are elastically or yieldingly mounted, with respect to the iixed support I4, the members 20, upon expansion, due to heating, press these segments outwardly a distance depending upon the amount of expansion. Since l the segments I9 are discontinuous, should nonor distortion of the various members 20 of which the cover is made can occur suiiiciently to cause jamming or distortion about the electrodes to interfere with their operation. Further, the pressure stresses of the cover and of the separate members of which it is made are made morev uniform due to the selective yielding possible as a result of the fact that the segments are discontinuous and separately mounted, and thus excessive tension within the cover which might be disastrous to it is avoided.

Upon cooling the separate members 20 under contraction are not separated from each other and distortion of the cover cannot occur, again because, due to the elastic or yielding mounting of the segments I9 with respect to the xed supporting ring I4, the members 20 are pressed inwardly again and so retain their original arrangement. Thus the elastic and yielding mounting of the edge of the cover, whether in the form of Figures 1 and 2 or of Figure 3, automatically permits and compensates for the expansion of the cover due to heating. It prevents crowding and jamming of the electrodes and prevents excessive tensions and stresses in and resultant damage to the cover, both during expansion and contraction.

I claim:

1. For use with an open topped furnace, a cover including a circumferential compression member, a self-supporting roof surrounded by the compression member including a plurality of fitted blocks of heat-resistant material adapted to expand or contract in response to temperature changes, andra plurality of -separate yielding means associated with said compression member and adapted to direct thrusts inwardly against the outer edge of said roof at various points thereabout, said roof being apertured to permit the' passage of electrodes therethrough.

2. For use with an open topped furnace, a cover including a circumferential compression member generally circular in form, a self-supporting roof surrounded by the compression member, including a-plurality of fitted blocks of heat-resistant material adapted to expand or contract in response to temperature changes, a plurality of abutment segments opposed to the edge of said roof, a plurality of separate yielding means associated with said compression member and adapted to direct thrusts'inwardly against said abutment segments at various points about the edge of said roof, said roof being apertured to permit the passage of electrodes therethrough.

3. For use with an open topped furnace, a cover including a circumferential compression member, a self-supporting roof surrounded by the compression member, including a plurality of tted blocks of heat-resistant material adapted to expand or contract in response to temperature changes, a plurality of abutment segments opposed to the edge of said roof,lguiding members therefor, said compression member being apertured to permit said guiding members to pass therethrough, and yielding mea-iis adapted to thrust said segments inwardly against the edge of said roof at various points thereabout.

PAUL HONEiGGER.

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