US3122600A

US3122600A - Electrode holder for electric furnaces

Info

Publication number: US3122600A
Application number: US89747A
Authority: US
Inventors: Souchet Joseph
Original assignee: Solumeta
Current assignee: Solumeta
Priority date: 1960-02-17
Filing date: 1961-02-16
Publication date: 1964-02-25
Anticipated expiration: 1981-02-25
Also published as: GB970718A; FR1257155A

Description

J. SOUCHET ELECTRODE HOLDER FOR ELECTRIC FURNACES Filed Feb. 16, 1961 IN VEN TOR. JOSEPH SOUCHET' BY /2/W?" A TTORNEY Feb. 25, 1964 w 1 I L mu 7//// R r 3,122,600 ELECTRODE HOLDER FOR ELECTRIC FURNACES Joseph Souchet, Riouperoux, France, assignor to Solumeta, Paris, France, a corporation of France Filed Feb. 16, 1961, Ser. No. 89,747 Claims priority, application France Feb. 17, 1960 5 Claims. (Cl. 13-14) The present invention, which is based on the researches of the applicant, relates to electrode holders for electric furnaces. It is particularly applicable to electric holders which are to be provided for sealed (closed) furnaces.

It is well known to improve the contact between an electrode and its current inlet clamp by increasing the contact surfaces. Thus, it is found advantageous, especially in the case of large diameter electrodes, to use clamps comprising a plurality of contact plates which, generally, are pivotally connected among themselves and pressed (clamped) onto the electrode.-

It is, nevertheless, difficult to increase to any large extent the number of contact plates, because the relative size of the spaces between the plates, with regard to the width of the latter, increases and, hence, there is no longer any gain in contact surface. For this reason, one is generally limited to six or eight contact plates, the electrode being then clamped on about 70% of its periphery.

The present invention makes it possible to increase in a large ratio the contact surface between the current inlet and the electrode because the totality of the electrode periphery is utilized for the current inlet. At the same time, the invention makes it possible to obtain a tight seal between the electrode and the electrode holder.

The present invention comprises the obtainment of electric contact between the electrode and the one or more elements of the electrode holder which receive the current, by packing between these two parts a comminuted or powdered material, which conducts the electric cur rent and which is heat resistant.

In a preferred but non-lirniting embodiment of the invention, the electrode holder is provided with a metallic tubular part or sleeve, which is concentric with the electrode and having an internal diameter larger than the diameter of the electrode, and acomminuted material is disposed in the annular. space between these two parts, means being provided for maintaining this material in a compacted condition.

According to the invention, the contact is established uniformly over the entire periphery of the electrode, thereby avoiding formation of hot spots or burned areas.

According to the intensity of the operating current of the electrode, the sleeve is chosen of a more or less greater length, and the current density is maintained between the usual limits by increasing the contact surface between the conducting powdered material and the electrode.

As conducting divided material, there is advantageous- United States Patent 0 3,122,600 Patented Feb. 25, 1964 one embodiment which has given good results, the upper part of the sleeve comprises a screw-type stufling box which compresses the graphite in the annular space provided therefor.

A still better contact is secured when the internal surface of the sleeve is given a slightly truncated profile (shape), the small base being directed towards the tip of the electrode; There is then produced a wedging effect which facilitates packing ofthe graphite.

The novel device according to the invention presents the advantage of providing not only an excellent electric joint, but also a joint which is sealed to gases between the electrode and the'part where the current is introduced, the said joint nevertheless enabling relative displacement between the electrode and the partwhere the current is introduced.

As a result of this fact, the novel electrode is especially advantageous when used for electric furnaces where the atmosphere of the hearth must be different in pressure and/or composition from the external atmosphere.

In a preferred but non-limiting embodiment of the invention, there are provided secondary tightening means for the electrode, the said secondary tightening means merely having a mechanical blocking function and being integral with the current inlet sleeve.

Moreover, there are provided, as usual, longitudinal translation means for the electrode for control purposes, the said means acting preferably on the sleeve or on the above-mentioned secondary tightening means for the elec trode.

According to the invention, there is obtained a sealed (tight) electrode holder by additionally providing between the parts of the electrode holder which are subjected to relative longitudinal displacement, tight sliding (expansion) joints of a heat-resistant material.

The present invention finds a particularly important application in the case where it is desired to obtain a sealed (tight) electrode holder, of variable inclination, an arrangement which makes it possible to maintain optimum spacing between the electrodes of the same furnace, in spite of variations in the level of the bath ly used graphite in the form of powder and/or flakes.

Good results are obtained by using a mixture of these two products, a better conductivity having been obtained by employing a mixture of approximately equal parts of powder and flakes.

One can also use for the conducting joint, in Whole or in part, carbides of refractory metals such as, and without limitation, carbides of tungsten, of molybdenum, of tantalum, of titanium, of zirconium, etc.

In a preferred embodiment of the invention, the sleeve is provided at its lower end with one or more packing rings to avoid loss of graphite, aloss which can be produced by entrainment when the electrode is displaced relatively to the sleeve.

Means are provided for pressing the graphite-at least when the electrodes are under current-both against the electrode and against the current inlet sleeve. Thus, in

therein.

The fixed part in the space of the electrode holder comprises a fixed sector-shaped base (seat), for example, on the roof of the furnace, and on whichis mounted an element, or electrode guide, having a surface complementary to that of the sector-shaped base.

By way of non-limiting examples, there are described below various preferred embodiments of the invention with reference to the annexed drawing in which FIGURE 1 represents, in (half) section, a current inlet arrangement according to the invention, and

FIGURE 2 shows in (half) section an embodiment of a sealed electrode holder having a variable inclination.

Aswill be seen by reference to FIGURE 1, the sleeve 1 of the electric holder has a slightly truncated internal surface 2. The electric current is led into said sleeve, for example, by means of a lug (thimble, socket) 3 connected to the cable 4. The sleeve 1 is moreover supported by any convenient means on a stationary portion of the installation, such as a cross piece, furnace roof, etc., not illustrated in the drawing, by the intermediary of any suitable longitudinal translation means such as a jack, pulley block, etc., which makes it possible to regulate the elevation of the electrode.

The electrode 5, is clamped in a locking collar (clamp) 6 integral with the sleeve 1, or integral with a part which is itself integral with said sleeve. i

The space 7 between the electrode and the internal face 2 of the sleeve is provided with a mixture of graphite scales and powder which is retained at the bottom by a) one or more graphite rings 8, and which is compressed by means of a stufiing-box 9.

When the electrode holder is intended for a large diameter electrode, supplementary guiding rings are advantageously provided for the electrode, in order that the electrode not be forced on the graphite ring 8.

The said ring 3 has for its object to retain the powderscale graphite mixture 'while permitting sliding of the electrode, so that its diameter should be adjusted with precision. In the case where the electrode diameter tolerances are appreciable, it may be advantageous to superpose several slit graphite rings, taking care that the slots are opposite to each other.

During operation of the furnace, a certain quantity of the graphite powder may be entrained, particularly so during the sliding operations of the electrode or during passage of the connecting nipples; it is for this reason that there is provided a guard on the stuffingbox 9 which can be periodically tightened when this becomes necessary.

Without departing from the scope of the invention, provision can be made in the case of electrodes of small diameters to carry out the mechanical tightening of the electrode in the electrode holder solely by means of the conductive joint of graphite scales, thereby eliminating the tightening clamp. It is advantageous to provide the stufiing-box with a remote control system, for example, one using a jack, whereby it is possible to release rapidly the clamping pressure of the flake joint, to facilitate sliding of the electrode.

On FIGURE 2 there is illustrated a special embodiment of the present invention in which advantage is taken of the seal (tightness) secured between the current inlet sleeve 1 and the electrode by reason of the provision of a conductive joint of graphite flakes.

FIGURE 2 shows a sealed (tight) and orientable electrode holder, which makes it possible to obtain a very precise regulation of arc furnaces provided with a controlled atmosphere.

In this embodiment, the electric contact between the sleeve 1, cooled by circulation of water in the tubes and the electrode 5 is assured, as previously described, by means of graphite powder and flakes which are packed in the space 7 by means of the stufiing-box 9, while the mechanical clamping of the electrode on the electrode holder is completed by a locking ring 6 integral with the sleeve.

The sleeve 1 is extended by a tubular skirt 11, likewise cooled, and comprising at its lower part a sealing joint 12 secured into a stuffing-box. The said joint is susceptible of sliding with a translation motion on the external surface of a tubular electrode guide 13, cooled by water circulation and eventually comprising a ring 14, or a portion of a ring, for guiding or supporting the electrode when the latter is not vertical, said guide being not liable to any translation motion.

Regulation of the electrode in height is carried out by means of any usual regulating device such as-illustrated by way of example on FIGURE 2one or more jacks 15 the cylinders of which rest on a fixed part used in the translation of the electrode holder, such as the tubular guide 13, and the pistons 16 of which act on the sleeve 1 or on a part which is integral with the latter.

To enable sliding motion, as the electrode is consumed, there is advantageously provided on the upper part of the electrode holder a guiding ring 17 integral with the fixed part of the electrode holder (part 13) through the intermediary of cheek plates, not shown on FIGURE 2.

When the pistons 16 of the jack 15 are at the end of their stroke and in their lower position, a collar 19 is pressed on the electrode which then rests on the fixed ring 17. The collar 6 is loosened and the electrode retained by the collar 19 remains stationary while the jacks are operated to raise the current inlet assembly.

The ring 6 is then re-cl-amped and the collar 19 is loosened, to again permit operation of the electrode by means of the jacks 15.

According to the preferred, although non-limiting, embodiment shown on FIGURE 2, the inclination of the electrode holder is rendered variable by providing for the tubular electrode guide 16, a cylindrical lower sup-. porting surface 2t) which rests on a corresponding surface of a cooled base 22-22 comprising an insulating joint 23 and fixed, for example, to the roof 24 of the furnace.

As will be readily understood, suitable means for pressing the cylindrical surfaces 2% and 22 against each other prevent any accidental inclination of the electrode holder, and flexible joints, such as 25, insure complete tightness of the pivoting arrangement.

As will be understood, any other modifications comprising variant embodiments of those which have been described in detail above come within the scope of the invention.

1 claim:

1. In an electric furnace, in combination: an electrode, a tubular electrode holder sleeve surrounding said electrode, spaced therefrom and provided with tubes for circulating a cooling medium; a divided, heat resistant conductive, carbon containing material in the space between the sleeve and the electrode, said space being defined by a conical surface; a current inlet arrangement for said holder and means for passing current into the latter; means for compressing the divided material to thereby establish at the same time close electric con-tact and sealing to gases between the sleeve and the electrode; a jack device integrally joined with both the sleeve and an electrode guide; an electrode clamping device in-tegrally joined with the sleeve and adapted to operate during the time of current passing into said holder and to be temporarily loosen-ed during the upward movement of said sleeve; another electrode clamping device 19, independent cf said sleeve, integrally joined with the electrode guide and adapted to be loosened during the time of current passing into said holder and to operate during said last mentioned upward movement; said jack device regulating the electrode in height.

2. An electric furnace according to claim 1, wherein the electrode holder sleeve comprises a downwardly ex tending tubular skirt having a sealing joint at its lower part secured into a stufiing box, thereby perfecting the gas-tightness of the electrode holder.

3. An electric furnace according to claim 1, provided with means for varying the inclination of the electrode, said means comprising complementary cooled sectorshaped parts, one of which is. integrally joined with the electrode guide, the other of which is integrally joined with the roof of the furnace.

4. An electric furnace according to claim 2, wherein the electrode guide is provided with a guiding ring.

5. An electric furnace according to claim 3, wherein the electrode guide is provided with a guiding ring.

References Cited in the file of this patent UNITED STATES PATENTS 846,521 Stevens Mar. 12, 1907 871,338 Heroult Nov. 19, 1907 908,407 Heroult Dec. 29, 8 1,173,960 Hechenbleikner Feb. 29, 1916 1,252,633 Vom Baur Jan. 8, 1918 1,363,815 Saklatwalla et a1 Dec. 28, 1920 1,637,052 Robinson July 26, 1927 1,737,890 Noichl et a1. Dec. 3, 1929 2,405,236 Rhoades et al Aug. 6, 1946

Claims

1. IN AN ELECTRIC FURNACE, IN COMBINATION: AN ELECTRODE, A TUBULAR ELECTRODE HOLDER SLEEVE SURROUNDING SAID ELECTRODE, SPACED THEREFROM AND PROVIDED WITH TUBES FOR CIRCULATING A COOLING MEDIUM; A DIVIDED, HEAT RESISTANT CONDUCTIVE, CARBON CONTAINING MATERIAL IN THE SPACE BETWEEN THE SLEEVE AND THE ELECTRODE, SAID SPACE BEING DEFINED BY A CONICAL SURFACE; A CURRENT INLET ARRANGEMENT FOR SAID HOLDER AND MEANS FOR PASSING CURRENT INTO THE LATTER; MEANS FOR COMPRESSING THE DIVIDED MATERIAL TO THEREBY ESTABLISH AT THE SAME TIME CLOSE ELECTRIC CONTACT AND SEALING TO GASES BETWEEN THE SLEEVE AND THE ELECTRODE; A JACK DEVICE INTEGRALLY JOINED WITH BOTH THE SLEEVE AND AN ELECTRODE GUIDE; AN ELECTRODE CLAMPING DEVICE INTEGRALLY JOINED WITH THE SLEEVE AND ADAPTED TO OPERATE DURING THE TIME OF CURRENT PASSING INTO SAID HOLDER AND TO BE TEMPORARILY LOOSENED DURING THE UPWARD MOVEMENT OF SAID SLEEVE; ANOTHER ELECTRODE CLAMPING DEVICE 19, INDEPENDENT OF SAID SLEEVE, INTEGRALLY JOINED WITH THE ELECTRODE GUIDE AND ADAPTED TO BE LOOSENED DURING THE TIME OF CURRENT PASSING INTO SAID HOLDER AND TO OPERATE DURING SAID LAST MENTIONED UPWARD MOVEMENT; SAID JACK DEVICE REGULATING THE ELECTRODE IN HEIGHT.